CA1331834C - Process for producing beta manganese dioxide - Google Patents
Process for producing beta manganese dioxideInfo
- Publication number
- CA1331834C CA1331834C CA000603550A CA603550A CA1331834C CA 1331834 C CA1331834 C CA 1331834C CA 000603550 A CA000603550 A CA 000603550A CA 603550 A CA603550 A CA 603550A CA 1331834 C CA1331834 C CA 1331834C
- Authority
- CA
- Canada
- Prior art keywords
- manganese dioxide
- beta
- tube
- manganese
- gamma
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/502—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese for non-aqueous cells
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G45/00—Compounds of manganese
- C01G45/02—Oxides; Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
Abstract
ABSTRACT
The present invention relates to an improved process for producing beta manganese dioxide and for producing cathodes from said manganese dioxide. The process comprises heating gamma manganese dioxide at at lest 450°C for up to one hour in order to convert a majority of the gamma manganese dioxide to the beta phase without forming detrimental amounts of lower oxides.
The present invention relates to an improved process for producing beta manganese dioxide and for producing cathodes from said manganese dioxide. The process comprises heating gamma manganese dioxide at at lest 450°C for up to one hour in order to convert a majority of the gamma manganese dioxide to the beta phase without forming detrimental amounts of lower oxides.
Description
`, ^ 1 33 ~ 834 PROCESS FOR PROOUCING BETA MANGANESE DIOXIOE
Thls 1nvention relates to an improved process for producing beta manganese d10xide. In part~cular, the present ~nvent10n relates to a method for converting gamma manganese dioxide to the beta crystal phase in very short time perlods and uslng said beta manganese dioxide as a cathode act~ve material in non-aqueous cells.
Mbnufacturers of manganese dloxide generally use an electrol~tlc, aqueous process whlth produces manganese dloxlde havlng a gamma tr~stal structure. It has long been known that before gamma manganese dlox~de can be used as cathode material ln a llth1um tel1 the manganese dloxlde must be heated to remove water and to change the tr~stal structure from the gamma phase to a predominantl~
beta phase. US patents ~,133,85C and 4,29~,231 dlstlose heat treatments of manganese diox1de at betweèn 250C and 430C for at least two hours to re~ove water and tonvert to the beta tr~stal phase. Heat treatment pertods of as long as 20 hours have been used b~ some manufatturers (see ~8. Llth1um-~anganese Dloxlde Cells~, bJ H. Ikeda, p. 173, Llth1um 8atterles, ed. J. P.
Cabano, Atademlc Press, (Ne~ ~or~ 1983)). Heretofore, lt has been the practlte not to exteed a temperature of ~50 & because a decomposlt~on of thc manganese dloxlde to lo~er oxldes ~as ~no~n to octur. In fact, US patent 4,133,856, teaches that heat treat~ent above UO & produces ~n203, whlch materlal adversel~ lmpacts the utlll2atlon of the manganese dloxldc cathode. Flgurcs 1 and 2 of that rcference show a decreasc ln utlll2atlon for hcat treatments abovc 3~5C.
; , . , ~ . , . ~ ~ . . , 133~834 The problem with the aforement10ned heat treatments ~s that the t1me requ~red at the specif~ed temperatures 1s too long for h19h volume cell product~on, The prlor art ~ethods would requ1re a large number of ovens to produce the amount of mater~al needed, Thus, there is a need to shorten the several hour heat treatment processes of the prtor art to shorter tlme per~ods The use hereln of phrases such as ~beta manganese dlox1de- and ~beta converted~, etc is not intended to mean that the gamma manganese diox~de has been converted to lOOZ beta Rather, ~t ls intended to mean that the manganese dloxide has been heat treated to convert a ma~orlty of the gamma crystal phase to the beta crystal phase In fact, as w111 be dlscussed below, it is preferred ~hat the manganese dloxlde ls less than lOOS beta so that the ~beta manganese d~oxidea discussed hereln 1s 1n reallty a gamma-beta mlx It ls thereforc an ob~eet of the present lnvent10n to prov1de a process for heat treatlng manganese dloxlde ln a short per10d of t1me to obtaln a beta manganese dtoxlde whlch behaves s1mllarly ln a cell to manganese dloxlde heated according to prlor art methods It ls an addltlonal ob~ect to provide a method wh~ch contlnuousl~ produces sald manganese d10xlde The present lnventlon 1s based on the dlscovery that temperatures at and above about 450 & can be used w1thout detrlmentally affectlng cell performance because the rate of the gar~a to beta converslon of manganese dloxide ls so uch faster than the rate of deco~posltlon of ~anganese d~oxide to lower oxlde~ that lt 1s posslble, ln accordance wlth the present lnventlon to convert the gamra ~nO2 to beta by heatlng partlculate gam~a manganese dloxlde above 450 & for only ~ fr~ctlon of an hour whereby mlnlmal decomposltlon to lower oxldes occurs.
. ~ . . . : -..- .... .
. ~
~ here are three time segments wh1ch make up the total heat treatment period: (1) the rise t1me to heat the MnO2 from amb1ent to the heat treatment temperature, tr; (2) the t1me at the heat treatment temperature, th; and (3) the time to cool the MnO2 from the heat treatment temperature to amblent, tc. In order to minimize the total heat treatment period 1t 1s 1mportant to have a ver~ short tr and tc . In th~s manner th becomes the controll1ng time per10d for the overall heat treatment process.
6amma MnO2 1s ava11able as a finely d1v1ded powder. In order to have a ver~ short tr it is necessar~ to have a ver~ effectlve transfer of heat from thc heat1ng oven to the 1nd1v1dual part1cles of the MnO2 powder . Further, the ent1re mass of MnO2 must be heated 1n a un1form manner 1n order to obta1n a homogeneous beta convers10n. Accord1ng to the present ~nvent10n, a method for prov~d1ng ver~ rap1d, un~form heat1ng co~prises pass1ng the MnO2 powder through a mult1-zoned rotar~ tube furnace ~also known as a rotar~ k11n or a rot~r~ dryer).
~ he features and advantages of the present 1nvent10n w111 be d1scussed belo~ with reference to the F1gures 1n wh1ch:
F~gure l 1s ~ plot of temperature v. locat10n 1n rotar~ tube for three dlfferent heat treat~ent te~peratures;
F~gure 2 1s a plot of terperature v. locat~on 1n the rotary tube for a furnace te~perature of ~5 ~ ; ~nd Figure 3A is an X-ray diffraction pattern of manganese dioxide according to the present invention; and Figure 3B is an X-ray diffraction pattern of manganese dioxide heat treated according to the prior art method.
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A rotary tube furnace comprises an elongated, rotatable, steel tube with heating elements arranged adjacent to a portion of the external surface of the tube ~or applying heat thereto. The tube generally dec1ines downwardly from the end where the powder is introduced to the end where the powder exit5. The powder is continuousty fed into one end and tumbles down the length of the tube as it slowly rotates. The rotation of the tube provides very effective heat transfer to the powder because the powder is in continuous motion and the particles in contact with the heated tube surface are constantly changing. The result is a very short tr. Once the powder has reached the heat treatment temperature the powder tumbles through the remainder of the heated zone in a time equal to th. The powder then passes into a cool down zone and exits the tube.
For example, a rotary tube furnace obtained from Harper Electric Furnace Inc.. Lancaster, ~.Y., is suitable to heat treat gamma manganese dioxide for conversion to a predominantly beta crystal phase. The rotary tube furnace has a stainless tube that is about 11.5 feet long and 7 inches in dlameter. The tube has an essentially smooth inner surface. The decline of the tube can be varied from O-S degrees. The tube can be rotated from O to 18 RPM. The time of passage of manganese dioxide through the tube is determined by the angle of decline and the RPM used. The furnace has three independent, consecutive heating zones, each being t~o feet long. The first zone begins two feet down the tube such that the last zone ends eight feet down the tube length. Thus, the last 3.5 feet of the tube are the cool down zohe.
The temperature profile of manganese dioxide passing through the tube will be discussed with reference to the following experiment. Three separate heat _ ~ . . .. . . . . .
~` " ' ~ ` ; ' `' ~ ;
~ ~ 1 33 1 834 treatments at 400C, 450C, and 500C were carried out. For each treatment the following procedure was used. All three heating zones were set to the same temperature. Manganese dioxide was fed through the tube at a rate of 0.6 pounds per minute. The angle of decline was one degree and the tube was rotated at 3 RPM wh1ch resulted in a veloc1ty of about 0.2 feet per minute of powder through the tube. Generally, when the furnace is started from ambient it ta~es about 2-3 hours to come to a steady state conditton. This condition is achieved when thermal equilibrium is reached between the heating elements, the - ~s tube, and the manganese dioxide. Thermocouples are placed every two feet down the length of the tube so that they are embedded 1n the manganese d10x1de powde- as it flows through the tube. The steady state is ach1eved when each thennocouple indicates a non-fluctuat1ng temperature. Figure 1 shows the steady state temperature prof11e down the length of the tube for the three heat treatment te~peratures. Each of the heat treatments was run for about two hours after reach1ng steady state 1n order to collect sufflc1ent mater1al for analysis. As the F1gure 1 shows, the heat treatment temperature ls reached in the thlrd zone located between 6 and 8 feet down the tube. Thus, the manganese dloxldc 1s heated for about 10 mlnutes at the max1mum heat treatment terperature of the part1cul~r run. It 1s belleved that the 9 _ a to beta cryst~l phase convers10n beg1ns around 350 & and Flgure 1 shows that the t1me abo~e th1s temper~ture ls longer than 10 mlnutes. Table 1 sho~s the var10us t1me per10ds for the three he~t tre~tment terperatures.
: . .
Table 1 Temperature (C) time to reach 350 & 26 21 18 time above 350 & 13 19 24 time at maximum temp. lO lO lO
Sbeta 40 60 87 Table l demonstrates that a hlgher heat~ng zone temperature w~ll g~ve a faster rise time to the beta conversion temperature (350C) and will also result ~n a longer tlme above that temperature when compared to a lower temperature at the same thm~ughput of material. Therefore, the total heat treatment t~me can be mlnimized by ma~nta~ning the heating zones at te~peratures above about 450 & . If temperatures as htgh as 500C are used care must be taken to avold heat treatment per~ods whlch w~ll be long enough to form lower oxides of manganese. ~hile the 60 m~nute run at 500C d~d not show an~ lower oxlde format~on, as determlned b~ X-r4y analysls, a s1mllar run for lOS mtnutes d~d sho~ some lower oxldes present. The F~gure also shows that the manganese dloxlde does not reach the te~perature of the heat~ng zones.
Therefore, the heat1ng zones need to be set at a temperature sl~ghtl~ above the deslred heat treatment terperature ~n order to reach that temperature.
The materlal obta1ned from each of the three heat treatments discussed above ~s anal~zed for the S beta converston. Thls anal~sls ls done us1ng X-ra~
dlffraction ~n the follow1ng manner. A sample of each powder is taken and the X-r~ d~ffract~on pattern ~s determ1ned us~ng Cu KC~ rad~ation. ~ monochrometer ls placed between the sample and a sc~nt~llat~on detector to remove fluorescent k ~
: -'`': `. ~
radiation. rhe llo reflection is used in the X beta determination by comparingthe number of counts at this reflection for the sample to the number of counts at this reflect10n for an external standard known to be IOOX beta. A ratio of the counts gives the X beta for the sample.
For manganese dioxide to have adequate performance as a cathode actlve material in a l~thium battery the X beta should be at least 60X but less than 90S. Outside of this range the cathode utilization is inferior to the utilizatlon of material within thls range. It is preferred the the X beta be between about 65S and 85X. Table l shows the X beta conversion at the three temperatures. Each value glven represents an average of three different samples ta~en from the same run. The data shows that a th of l9 minutes 1s sufficient to convert g~mna manganese d10xide to about 60S beta when the heating zones arc set at 450 &. Th1s ls adequate converslon for use as cathode active manganese d10x~de ln a non-aqueous cell. ~hlle 400 & ls an adequate heat treatment te~perature uslng the long prior art tlme perlods, lt ls not an adequate te~perature for the short tlmes of the present invention as indicated b~ the 40S beta convers10n.
nhe beneflt of the present tnvention ls that it provides a contlnuous process for con n rtlng large quant1ttes of gamna ranganese d10xtdc to the beta phase ln shorter t1me perlods than the processes taught b~ the prior art wlthout the fornatlon of d leterlous lower oxldes. ~hat follows is a dlscuss~on of an extend ~ productlon run of 48 hour duratlon whlch demonstrates a preferred mod of operatlon. The heatlng ~ones were e~ch set at 47s&. The tube angle was one degree and the rate of rotatlon was 3 RP~. The feedrate was 0.6 pounds per mlnute and the tlme for pass~ge down the entlre length of the .~_ ~ 1 33 1 834 tube was 55 m1nutes. It took about two hours to reach the steady state condition. The manganese dioxlde collected dur1ng this per10d was scrapped. The heat treatment then proceeded continuously for 46 hours w1th samples collected period1cally throughout the run. Thermocouples were located ever~ two feet down the length of the tube and the temperature profile of the manganese d10x1de 1s shown in Figure 2. The maxlmum temperature reached was about 470C and the manganese d10xide was heated between 450-470C for about 10 m1nutes.
At the end of 46 hours about 1600 pounds of the beta manganese dlox1de had been collected. The average X beta of the samples taken throughout the run was about 80t beta. The x in MnOx 1nd1cates the ox1dat10n state of manganese.
6anna manganese d~ox1de has x~1.95 before heat treatment due to the presence of - other manganese spec1es. The value of x was determlned b~ chem1cal anal~s1s for the mater1al prepared accord1ng to the present lnventton and 1t was found to be I.95 wh1ch 1ndlcates no decomposlt10n had occurred. ~ wa~ of compar1son, the pr10r art method of ba~c~wtse heat1ng at 350 & produced l90 lbs of about beta manganese dlox1de 1n a 24 hour heat treatment per10d. The present 1nvent10n, as described 1mmed1atel~ above. produces 864 pounds 1n the same per10d. Thus, more than a fourfold 1ncrease ln product10n of cathode qual1t~
beta manganese d10x1de ~as obta1ned b~ thc present invent10n under the above cond1tlons. For te~peratur-* above 450 & 1t 1s poss1ble to decrease th and thus the productlon rate could be h1gher.
Figures 3A and 3~ show the X-ray diffraction patterns of manganese - ~ -dioxide heat treated according to the present method and the prior art method, respectively. The diffraction patterns were obtained us1ng Cu Kc~ rad1at10n and scann1ng the 20 angle fror 15 to 40 degrees. The _~_ .......
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' ' . ` -.
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1 33 ~ 834 ,, position of the 110 reflect~on is due to latt k e spac~ng of the beta phase Theprior art material was 81S beta and the material made in accordance with the present invention was 82X beta The diffraction patterns are virtuall~
identlcal which confirms that the present lnvent10n prov~des similar material to that made b~ prior art methods The absence of any reflections at about 33 degrees ind1cates the absence of any expected tower oxides The X beta convers10n can be increased by holding the manganese d10xide at the heat treatment temperature for longer than 10 minutes However, for a given heat treatment temperature a ma~orit~ of the beta conversion takes place ln the first ten minutes For example, in the 450 & heat treatment discussed above the beta co m ers10n ls about 60X in thc flrst ten minutes and increases to onl~65X ~hen heated for a total of 90 mlnutes Therefore, the X beta is lncreased faster b~ he~t1ng at a hlgher temperature than b~ heating longer at a lower temperature ~ccordlng to the present 1nvention it ls possi~le to heat treat the ranganese dloxlde for up to one hour above 450 & but is preferred to heat for no more than 30 mlnutes at a heat treatment temperature above 450 C
As dlscussed above, ln order to mlnlml2e the total heat treatment perlod it ~ -ls deslrable to m1nlml~e tr. In the above descrlbed heat treatments, tr was gene-all~ less than l hour. It would not be detrl ental to the beta manganese dloxlde ult1ratel~ forn d 1f thls perlod was longer th~n I hour because lower oxldes do not fona ~t the te~per~tures whlch are reached durlng thls period.
However, lt 1~ preferred th~t tr not exceed one hour ln order to maxlml~- the throughput of manganese dloxlde Following the he~t treatment of gam~a manganese dioxide to the beta phase a c~thode can be prepared 1n a conventlonal manner. For example, the heat treated _g_ ~'' ' -' ,, ,~ ' .
1 33 ~ 83 4 manganese dloxlde ls comb1ned w1th a conductlve agent and a blnder The ad~ixture ls then formed lnto the deslred cathode structure. For a button cell the cathode ls formed b~ press1ng the admlxture lnto a dlsc shape and the d1sc ~s pressed into the cathode can of the button cel1 For a splrally wound cell the admixture ls applted to both sldes of a conductlve metal gr1d and compressed between rollers to obtaln proper adherence A long, thtn cathode is obtained wh1ch can be splrally wound together wlth an anode and separator ~ he conductive agents su~table for use lnclude an~ of those conductive agents convent~onall~ emplo~ed ln the art for produclng posltlve electrodes for non-aqueous cells and 1ncludes acet~lene black and carbon black. The blnders for use ln the process are also materlals known ~n the art for preparing pos~tive electrodes of m~nganese dloxlde for non-aqueous cells and wh~ch are c~p~ble of provldlng sufflclent blndlng propertles. Sultable blnders are fluorlc res1ns lncludlng pol~tetrafluoroeth~lene, copol~mers of tetrafluoroeth~lene and hexafluoroprop~lene, copol~ers of tetr~fluoroeth~lene and eth~lene and chlorotrifluoroeth~lene.
~ fter the c~thode ls formed lt 1s sub~ect d to ~ he~t tre~tment to remove absorbed ~ater. Th1s he~t tre~tment ls generall~ done bet~een 150-300C and can be done ln dr~ ~lr or under vacuum. follo~1ng thls heat tre~t~ent the drled cathodes are assembled lnto cells.
An ~dmlxtu~re ls prep r d th~t ls 91S of the above descrlbed heat treated b ta mang~nese-~d1Oxlde, 6S c~rbon, and 3S pol~tetrafluoroeth~lene. The adn1xture ls coated on both sldes of an exp~nded, stalnless steel gr1d and the co~ted grld ls compressed between rollers Cathodes thus prepared are he~t treated at 200C under vacuum. The drled cathodes are splrall~ ~ound together ,~. . .- , . ,. , - . . ~ , -, ~ - , .
, , . , . ~
r..
1 33 ~ 83 4 with an anode comprlsed of lithium foil and a separator comprised of microporous polyprop~lene. The sp~rall~ wound electrode stack ~s inserted into a c~lindrical can. A convent~onal non-aqueous electrol~te ~s d~spensed into the can and a cover ls crlmped in place. Each electrode has a tab connected thereto. One tab connects to the can and the other tab connects to the cover, said can ana cover function1ng as the electrode terminals.
Such cells, havlng cathode actlve, beta manganese d~o%ide made in accordance with the present invention, have electrical discharge characteristics slmtlar to cells havlng manganese dloxlde heat treated according to the pr10r art methods. Thus, the rapid heating of the present lnventlon does not adversel~ effect the electrochemlcal propertles of the manganese dioxide.
Yarlatlons, whlch are wlthln the scope of the present lnvention, can be made to the above descr1bed heat treatment process. For example, the gamma manganese dlox1de could be separatel~ pre-heated up to about 300C before lntroduction into the rotar~ tube. Thls would shorten the overall res~dence tlme of the manganese dlox1de ln the heatlng zone and lncrease the rate of productlon. The heat released b~ the manganese dloxlde ln the cool do~n zone of the tube could be transferred and used ln the preheat for a more efflcient use of energ~. An effle1ent h at removal ln the cool down zone could also serve to shorten the o~er~ll p-oees~ tlme.
ootar~ kll~ t ehnolog~ ls well known and there is an equatlon whlch descrlbes the relatlonshlp between between the angle of decllne, the rate of rotatlon, ànd the resldence tlme ln the tube:
T ~ (~L)/(DRtan(A)) , .;, ;.. -.. ~ . .. ..... - -.-- ~ -. - . ~ : -. . - - . . .
:
,.~. . . .:
~.: : ,-. ~;
~ . . .
~, . . : ` ' : : : 1 3 3 1 8 3 4 where T ls the t~me of passage, K is a constant, L is the length of the tube, D
is the d~ameter of the tube, R is the RPM rotat~on, and A ls the angle of the ~-tube. Thus, while an angle of one degree and a rotation of 3 RPM was used above, other angles and rates of rotatlon could be used to provide the same residence t1me or dlfferent resldence t1mes. Further, wh11e the feed rate of manganese d~ox~de ~s preferred to be between 0.1 and 1.0 pounds per m~nute for the above descrlbed rotary tube furnace, lt can be operated at rates up to about 3 pounds per mtnute. Much larger rates can be used with furnaces larger than the one descrlbed hereln.
The rota~y tube furnace descrlbed above ls comprlsed of a tube havlng an essentlall~ smooth lnner surface. The lnner surface could be modlfled to provide better mlx~ng of the manganese dloxlde powder. For example, longitudlnal f1ns could bc provlded ~t a 90 degree spaclng do~n the length of thc tube. ~be f1ns would funetlon as 11fters whlch would plck the manganese d10xlde up h1gher than oecurs wlth the smootb surf~ce ~nd pour the powder back to~ord the center of the tube. Another embodlment would be to have a corrugated lnner surface wblch would entra1n ~aterlal durlng rot~tlon ~nd pour ~t b~ck lnto the tube center.
6a~a manganese dloxlde contalns up to SS water as reeelved fron the manufacturer. Ourtng the heat treatment ~ost of tbls wattr ls removed ~nd a means for lts sc pe fro~ th- furnace must be provlded. An addltlonal functlon of tbe deellne of the rotar~ tube ls to provlde a ~chlmne~ effect~ so that the ~ter vapor esc-pes fron the upper end of the tube. ~o asslst ln the water v~por removal an lnert gas could be passed fro~ the lower end to the upper end : - ~
, ,, , . . ,~ , .. , .. , , . , .. , . , -., . .. ~ .. .. . , . - -.. -1 33 ~ 834 of the tube. However, the rate of gas flow should not be so great that manganese dtoxtde parttcles are entralned and carrted up the tube.
There extsts means other than a rotary tube furnace whtch could rapldty heat manganese dtoxide. For example, a flutdtzed bed through which heated a1r ts passed would provtde rap1d heat~ng. In thts process the gamma manganese dioxide powder ~s conveyed into the flutdtzed bed chamber. A raptd, upward flow of hot air dtsperses the powder tnto a flutdtzed bed and heats the powder to the heat treatment temperature tn a short period of ttme. The powder rematns in the chamber for a ttme sufftc1ent to obtatn the beta convers10n and then the converted powder ts collected and conve~ved out of the chamber to cool down.
Heat1ng methods such as th1s are amenable to etther contlnucus or batch operat10n.
Other var1at10ns can be made to the above descrtbed process and rematn w1thtn the scope of the present tnventton. The spec1ftc descr1pt10ns g1ven above relat1ng to the method of th1s 1nvent~on are for illustrattve purposes and are not tntended to 11m1t the scope of the 1nventton as clatmed.
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Thls 1nvention relates to an improved process for producing beta manganese d10xide. In part~cular, the present ~nvent10n relates to a method for converting gamma manganese dioxide to the beta crystal phase in very short time perlods and uslng said beta manganese dioxide as a cathode act~ve material in non-aqueous cells.
Mbnufacturers of manganese dloxide generally use an electrol~tlc, aqueous process whlth produces manganese dloxlde havlng a gamma tr~stal structure. It has long been known that before gamma manganese dlox~de can be used as cathode material ln a llth1um tel1 the manganese dloxlde must be heated to remove water and to change the tr~stal structure from the gamma phase to a predominantl~
beta phase. US patents ~,133,85C and 4,29~,231 dlstlose heat treatments of manganese diox1de at betweèn 250C and 430C for at least two hours to re~ove water and tonvert to the beta tr~stal phase. Heat treatment pertods of as long as 20 hours have been used b~ some manufatturers (see ~8. Llth1um-~anganese Dloxlde Cells~, bJ H. Ikeda, p. 173, Llth1um 8atterles, ed. J. P.
Cabano, Atademlc Press, (Ne~ ~or~ 1983)). Heretofore, lt has been the practlte not to exteed a temperature of ~50 & because a decomposlt~on of thc manganese dloxlde to lo~er oxldes ~as ~no~n to octur. In fact, US patent 4,133,856, teaches that heat treat~ent above UO & produces ~n203, whlch materlal adversel~ lmpacts the utlll2atlon of the manganese dloxldc cathode. Flgurcs 1 and 2 of that rcference show a decreasc ln utlll2atlon for hcat treatments abovc 3~5C.
; , . , ~ . , . ~ ~ . . , 133~834 The problem with the aforement10ned heat treatments ~s that the t1me requ~red at the specif~ed temperatures 1s too long for h19h volume cell product~on, The prlor art ~ethods would requ1re a large number of ovens to produce the amount of mater~al needed, Thus, there is a need to shorten the several hour heat treatment processes of the prtor art to shorter tlme per~ods The use hereln of phrases such as ~beta manganese dlox1de- and ~beta converted~, etc is not intended to mean that the gamma manganese diox~de has been converted to lOOZ beta Rather, ~t ls intended to mean that the manganese dloxide has been heat treated to convert a ma~orlty of the gamma crystal phase to the beta crystal phase In fact, as w111 be dlscussed below, it is preferred ~hat the manganese dloxlde ls less than lOOS beta so that the ~beta manganese d~oxidea discussed hereln 1s 1n reallty a gamma-beta mlx It ls thereforc an ob~eet of the present lnvent10n to prov1de a process for heat treatlng manganese dloxlde ln a short per10d of t1me to obtaln a beta manganese dtoxlde whlch behaves s1mllarly ln a cell to manganese dloxlde heated according to prlor art methods It ls an addltlonal ob~ect to provide a method wh~ch contlnuousl~ produces sald manganese d10xlde The present lnventlon 1s based on the dlscovery that temperatures at and above about 450 & can be used w1thout detrlmentally affectlng cell performance because the rate of the gar~a to beta converslon of manganese dloxide ls so uch faster than the rate of deco~posltlon of ~anganese d~oxide to lower oxlde~ that lt 1s posslble, ln accordance wlth the present lnventlon to convert the gamra ~nO2 to beta by heatlng partlculate gam~a manganese dloxlde above 450 & for only ~ fr~ctlon of an hour whereby mlnlmal decomposltlon to lower oxldes occurs.
. ~ . . . : -..- .... .
. ~
~ here are three time segments wh1ch make up the total heat treatment period: (1) the rise t1me to heat the MnO2 from amb1ent to the heat treatment temperature, tr; (2) the t1me at the heat treatment temperature, th; and (3) the time to cool the MnO2 from the heat treatment temperature to amblent, tc. In order to minimize the total heat treatment period 1t 1s 1mportant to have a ver~ short tr and tc . In th~s manner th becomes the controll1ng time per10d for the overall heat treatment process.
6amma MnO2 1s ava11able as a finely d1v1ded powder. In order to have a ver~ short tr it is necessar~ to have a ver~ effectlve transfer of heat from thc heat1ng oven to the 1nd1v1dual part1cles of the MnO2 powder . Further, the ent1re mass of MnO2 must be heated 1n a un1form manner 1n order to obta1n a homogeneous beta convers10n. Accord1ng to the present ~nvent10n, a method for prov~d1ng ver~ rap1d, un~form heat1ng co~prises pass1ng the MnO2 powder through a mult1-zoned rotar~ tube furnace ~also known as a rotar~ k11n or a rot~r~ dryer).
~ he features and advantages of the present 1nvent10n w111 be d1scussed belo~ with reference to the F1gures 1n wh1ch:
F~gure l 1s ~ plot of temperature v. locat10n 1n rotar~ tube for three dlfferent heat treat~ent te~peratures;
F~gure 2 1s a plot of terperature v. locat~on 1n the rotary tube for a furnace te~perature of ~5 ~ ; ~nd Figure 3A is an X-ray diffraction pattern of manganese dioxide according to the present invention; and Figure 3B is an X-ray diffraction pattern of manganese dioxide heat treated according to the prior art method.
~ . - ~ . - - . .
- ~ ,....... .
. ' .. :- . - .;: ' , . , .
. : . ., ~ 1 33 1 834 ~
A rotary tube furnace comprises an elongated, rotatable, steel tube with heating elements arranged adjacent to a portion of the external surface of the tube ~or applying heat thereto. The tube generally dec1ines downwardly from the end where the powder is introduced to the end where the powder exit5. The powder is continuousty fed into one end and tumbles down the length of the tube as it slowly rotates. The rotation of the tube provides very effective heat transfer to the powder because the powder is in continuous motion and the particles in contact with the heated tube surface are constantly changing. The result is a very short tr. Once the powder has reached the heat treatment temperature the powder tumbles through the remainder of the heated zone in a time equal to th. The powder then passes into a cool down zone and exits the tube.
For example, a rotary tube furnace obtained from Harper Electric Furnace Inc.. Lancaster, ~.Y., is suitable to heat treat gamma manganese dioxide for conversion to a predominantly beta crystal phase. The rotary tube furnace has a stainless tube that is about 11.5 feet long and 7 inches in dlameter. The tube has an essentially smooth inner surface. The decline of the tube can be varied from O-S degrees. The tube can be rotated from O to 18 RPM. The time of passage of manganese dioxide through the tube is determined by the angle of decline and the RPM used. The furnace has three independent, consecutive heating zones, each being t~o feet long. The first zone begins two feet down the tube such that the last zone ends eight feet down the tube length. Thus, the last 3.5 feet of the tube are the cool down zohe.
The temperature profile of manganese dioxide passing through the tube will be discussed with reference to the following experiment. Three separate heat _ ~ . . .. . . . . .
~` " ' ~ ` ; ' `' ~ ;
~ ~ 1 33 1 834 treatments at 400C, 450C, and 500C were carried out. For each treatment the following procedure was used. All three heating zones were set to the same temperature. Manganese dioxide was fed through the tube at a rate of 0.6 pounds per minute. The angle of decline was one degree and the tube was rotated at 3 RPM wh1ch resulted in a veloc1ty of about 0.2 feet per minute of powder through the tube. Generally, when the furnace is started from ambient it ta~es about 2-3 hours to come to a steady state conditton. This condition is achieved when thermal equilibrium is reached between the heating elements, the - ~s tube, and the manganese dioxide. Thermocouples are placed every two feet down the length of the tube so that they are embedded 1n the manganese d10x1de powde- as it flows through the tube. The steady state is ach1eved when each thennocouple indicates a non-fluctuat1ng temperature. Figure 1 shows the steady state temperature prof11e down the length of the tube for the three heat treatment te~peratures. Each of the heat treatments was run for about two hours after reach1ng steady state 1n order to collect sufflc1ent mater1al for analysis. As the F1gure 1 shows, the heat treatment temperature ls reached in the thlrd zone located between 6 and 8 feet down the tube. Thus, the manganese dloxldc 1s heated for about 10 mlnutes at the max1mum heat treatment terperature of the part1cul~r run. It 1s belleved that the 9 _ a to beta cryst~l phase convers10n beg1ns around 350 & and Flgure 1 shows that the t1me abo~e th1s temper~ture ls longer than 10 mlnutes. Table 1 sho~s the var10us t1me per10ds for the three he~t tre~tment terperatures.
: . .
Table 1 Temperature (C) time to reach 350 & 26 21 18 time above 350 & 13 19 24 time at maximum temp. lO lO lO
Sbeta 40 60 87 Table l demonstrates that a hlgher heat~ng zone temperature w~ll g~ve a faster rise time to the beta conversion temperature (350C) and will also result ~n a longer tlme above that temperature when compared to a lower temperature at the same thm~ughput of material. Therefore, the total heat treatment t~me can be mlnimized by ma~nta~ning the heating zones at te~peratures above about 450 & . If temperatures as htgh as 500C are used care must be taken to avold heat treatment per~ods whlch w~ll be long enough to form lower oxides of manganese. ~hile the 60 m~nute run at 500C d~d not show an~ lower oxlde format~on, as determlned b~ X-r4y analysls, a s1mllar run for lOS mtnutes d~d sho~ some lower oxldes present. The F~gure also shows that the manganese dloxlde does not reach the te~perature of the heat~ng zones.
Therefore, the heat1ng zones need to be set at a temperature sl~ghtl~ above the deslred heat treatment terperature ~n order to reach that temperature.
The materlal obta1ned from each of the three heat treatments discussed above ~s anal~zed for the S beta converston. Thls anal~sls ls done us1ng X-ra~
dlffraction ~n the follow1ng manner. A sample of each powder is taken and the X-r~ d~ffract~on pattern ~s determ1ned us~ng Cu KC~ rad~ation. ~ monochrometer ls placed between the sample and a sc~nt~llat~on detector to remove fluorescent k ~
: -'`': `. ~
radiation. rhe llo reflection is used in the X beta determination by comparingthe number of counts at this reflection for the sample to the number of counts at this reflect10n for an external standard known to be IOOX beta. A ratio of the counts gives the X beta for the sample.
For manganese dioxide to have adequate performance as a cathode actlve material in a l~thium battery the X beta should be at least 60X but less than 90S. Outside of this range the cathode utilization is inferior to the utilizatlon of material within thls range. It is preferred the the X beta be between about 65S and 85X. Table l shows the X beta conversion at the three temperatures. Each value glven represents an average of three different samples ta~en from the same run. The data shows that a th of l9 minutes 1s sufficient to convert g~mna manganese d10xide to about 60S beta when the heating zones arc set at 450 &. Th1s ls adequate converslon for use as cathode active manganese d10x~de ln a non-aqueous cell. ~hlle 400 & ls an adequate heat treatment te~perature uslng the long prior art tlme perlods, lt ls not an adequate te~perature for the short tlmes of the present invention as indicated b~ the 40S beta convers10n.
nhe beneflt of the present tnvention ls that it provides a contlnuous process for con n rtlng large quant1ttes of gamna ranganese d10xtdc to the beta phase ln shorter t1me perlods than the processes taught b~ the prior art wlthout the fornatlon of d leterlous lower oxldes. ~hat follows is a dlscuss~on of an extend ~ productlon run of 48 hour duratlon whlch demonstrates a preferred mod of operatlon. The heatlng ~ones were e~ch set at 47s&. The tube angle was one degree and the rate of rotatlon was 3 RP~. The feedrate was 0.6 pounds per mlnute and the tlme for pass~ge down the entlre length of the .~_ ~ 1 33 1 834 tube was 55 m1nutes. It took about two hours to reach the steady state condition. The manganese dioxlde collected dur1ng this per10d was scrapped. The heat treatment then proceeded continuously for 46 hours w1th samples collected period1cally throughout the run. Thermocouples were located ever~ two feet down the length of the tube and the temperature profile of the manganese d10x1de 1s shown in Figure 2. The maxlmum temperature reached was about 470C and the manganese d10xide was heated between 450-470C for about 10 m1nutes.
At the end of 46 hours about 1600 pounds of the beta manganese dlox1de had been collected. The average X beta of the samples taken throughout the run was about 80t beta. The x in MnOx 1nd1cates the ox1dat10n state of manganese.
6anna manganese d~ox1de has x~1.95 before heat treatment due to the presence of - other manganese spec1es. The value of x was determlned b~ chem1cal anal~s1s for the mater1al prepared accord1ng to the present lnventton and 1t was found to be I.95 wh1ch 1ndlcates no decomposlt10n had occurred. ~ wa~ of compar1son, the pr10r art method of ba~c~wtse heat1ng at 350 & produced l90 lbs of about beta manganese dlox1de 1n a 24 hour heat treatment per10d. The present 1nvent10n, as described 1mmed1atel~ above. produces 864 pounds 1n the same per10d. Thus, more than a fourfold 1ncrease ln product10n of cathode qual1t~
beta manganese d10x1de ~as obta1ned b~ thc present invent10n under the above cond1tlons. For te~peratur-* above 450 & 1t 1s poss1ble to decrease th and thus the productlon rate could be h1gher.
Figures 3A and 3~ show the X-ray diffraction patterns of manganese - ~ -dioxide heat treated according to the present method and the prior art method, respectively. The diffraction patterns were obtained us1ng Cu Kc~ rad1at10n and scann1ng the 20 angle fror 15 to 40 degrees. The _~_ .......
' .
' ' . ` -.
.
1 33 ~ 834 ,, position of the 110 reflect~on is due to latt k e spac~ng of the beta phase Theprior art material was 81S beta and the material made in accordance with the present invention was 82X beta The diffraction patterns are virtuall~
identlcal which confirms that the present lnvent10n prov~des similar material to that made b~ prior art methods The absence of any reflections at about 33 degrees ind1cates the absence of any expected tower oxides The X beta convers10n can be increased by holding the manganese d10xide at the heat treatment temperature for longer than 10 minutes However, for a given heat treatment temperature a ma~orit~ of the beta conversion takes place ln the first ten minutes For example, in the 450 & heat treatment discussed above the beta co m ers10n ls about 60X in thc flrst ten minutes and increases to onl~65X ~hen heated for a total of 90 mlnutes Therefore, the X beta is lncreased faster b~ he~t1ng at a hlgher temperature than b~ heating longer at a lower temperature ~ccordlng to the present 1nvention it ls possi~le to heat treat the ranganese dloxlde for up to one hour above 450 & but is preferred to heat for no more than 30 mlnutes at a heat treatment temperature above 450 C
As dlscussed above, ln order to mlnlml2e the total heat treatment perlod it ~ -ls deslrable to m1nlml~e tr. In the above descrlbed heat treatments, tr was gene-all~ less than l hour. It would not be detrl ental to the beta manganese dloxlde ult1ratel~ forn d 1f thls perlod was longer th~n I hour because lower oxldes do not fona ~t the te~per~tures whlch are reached durlng thls period.
However, lt 1~ preferred th~t tr not exceed one hour ln order to maxlml~- the throughput of manganese dloxlde Following the he~t treatment of gam~a manganese dioxide to the beta phase a c~thode can be prepared 1n a conventlonal manner. For example, the heat treated _g_ ~'' ' -' ,, ,~ ' .
1 33 ~ 83 4 manganese dloxlde ls comb1ned w1th a conductlve agent and a blnder The ad~ixture ls then formed lnto the deslred cathode structure. For a button cell the cathode ls formed b~ press1ng the admlxture lnto a dlsc shape and the d1sc ~s pressed into the cathode can of the button cel1 For a splrally wound cell the admixture ls applted to both sldes of a conductlve metal gr1d and compressed between rollers to obtaln proper adherence A long, thtn cathode is obtained wh1ch can be splrally wound together wlth an anode and separator ~ he conductive agents su~table for use lnclude an~ of those conductive agents convent~onall~ emplo~ed ln the art for produclng posltlve electrodes for non-aqueous cells and 1ncludes acet~lene black and carbon black. The blnders for use ln the process are also materlals known ~n the art for preparing pos~tive electrodes of m~nganese dloxlde for non-aqueous cells and wh~ch are c~p~ble of provldlng sufflclent blndlng propertles. Sultable blnders are fluorlc res1ns lncludlng pol~tetrafluoroeth~lene, copol~mers of tetrafluoroeth~lene and hexafluoroprop~lene, copol~ers of tetr~fluoroeth~lene and eth~lene and chlorotrifluoroeth~lene.
~ fter the c~thode ls formed lt 1s sub~ect d to ~ he~t tre~tment to remove absorbed ~ater. Th1s he~t tre~tment ls generall~ done bet~een 150-300C and can be done ln dr~ ~lr or under vacuum. follo~1ng thls heat tre~t~ent the drled cathodes are assembled lnto cells.
An ~dmlxtu~re ls prep r d th~t ls 91S of the above descrlbed heat treated b ta mang~nese-~d1Oxlde, 6S c~rbon, and 3S pol~tetrafluoroeth~lene. The adn1xture ls coated on both sldes of an exp~nded, stalnless steel gr1d and the co~ted grld ls compressed between rollers Cathodes thus prepared are he~t treated at 200C under vacuum. The drled cathodes are splrall~ ~ound together ,~. . .- , . ,. , - . . ~ , -, ~ - , .
, , . , . ~
r..
1 33 ~ 83 4 with an anode comprlsed of lithium foil and a separator comprised of microporous polyprop~lene. The sp~rall~ wound electrode stack ~s inserted into a c~lindrical can. A convent~onal non-aqueous electrol~te ~s d~spensed into the can and a cover ls crlmped in place. Each electrode has a tab connected thereto. One tab connects to the can and the other tab connects to the cover, said can ana cover function1ng as the electrode terminals.
Such cells, havlng cathode actlve, beta manganese d~o%ide made in accordance with the present invention, have electrical discharge characteristics slmtlar to cells havlng manganese dloxlde heat treated according to the pr10r art methods. Thus, the rapid heating of the present lnventlon does not adversel~ effect the electrochemlcal propertles of the manganese dioxide.
Yarlatlons, whlch are wlthln the scope of the present lnvention, can be made to the above descr1bed heat treatment process. For example, the gamma manganese dlox1de could be separatel~ pre-heated up to about 300C before lntroduction into the rotar~ tube. Thls would shorten the overall res~dence tlme of the manganese dlox1de ln the heatlng zone and lncrease the rate of productlon. The heat released b~ the manganese dloxlde ln the cool do~n zone of the tube could be transferred and used ln the preheat for a more efflcient use of energ~. An effle1ent h at removal ln the cool down zone could also serve to shorten the o~er~ll p-oees~ tlme.
ootar~ kll~ t ehnolog~ ls well known and there is an equatlon whlch descrlbes the relatlonshlp between between the angle of decllne, the rate of rotatlon, ànd the resldence tlme ln the tube:
T ~ (~L)/(DRtan(A)) , .;, ;.. -.. ~ . .. ..... - -.-- ~ -. - . ~ : -. . - - . . .
:
,.~. . . .:
~.: : ,-. ~;
~ . . .
~, . . : ` ' : : : 1 3 3 1 8 3 4 where T ls the t~me of passage, K is a constant, L is the length of the tube, D
is the d~ameter of the tube, R is the RPM rotat~on, and A ls the angle of the ~-tube. Thus, while an angle of one degree and a rotation of 3 RPM was used above, other angles and rates of rotatlon could be used to provide the same residence t1me or dlfferent resldence t1mes. Further, wh11e the feed rate of manganese d~ox~de ~s preferred to be between 0.1 and 1.0 pounds per m~nute for the above descrlbed rotary tube furnace, lt can be operated at rates up to about 3 pounds per mtnute. Much larger rates can be used with furnaces larger than the one descrlbed hereln.
The rota~y tube furnace descrlbed above ls comprlsed of a tube havlng an essentlall~ smooth lnner surface. The lnner surface could be modlfled to provide better mlx~ng of the manganese dloxlde powder. For example, longitudlnal f1ns could bc provlded ~t a 90 degree spaclng do~n the length of thc tube. ~be f1ns would funetlon as 11fters whlch would plck the manganese d10xlde up h1gher than oecurs wlth the smootb surf~ce ~nd pour the powder back to~ord the center of the tube. Another embodlment would be to have a corrugated lnner surface wblch would entra1n ~aterlal durlng rot~tlon ~nd pour ~t b~ck lnto the tube center.
6a~a manganese dloxlde contalns up to SS water as reeelved fron the manufacturer. Ourtng the heat treatment ~ost of tbls wattr ls removed ~nd a means for lts sc pe fro~ th- furnace must be provlded. An addltlonal functlon of tbe deellne of the rotar~ tube ls to provlde a ~chlmne~ effect~ so that the ~ter vapor esc-pes fron the upper end of the tube. ~o asslst ln the water v~por removal an lnert gas could be passed fro~ the lower end to the upper end : - ~
, ,, , . . ,~ , .. , .. , , . , .. , . , -., . .. ~ .. .. . , . - -.. -1 33 ~ 834 of the tube. However, the rate of gas flow should not be so great that manganese dtoxtde parttcles are entralned and carrted up the tube.
There extsts means other than a rotary tube furnace whtch could rapldty heat manganese dtoxide. For example, a flutdtzed bed through which heated a1r ts passed would provtde rap1d heat~ng. In thts process the gamma manganese dioxide powder ~s conveyed into the flutdtzed bed chamber. A raptd, upward flow of hot air dtsperses the powder tnto a flutdtzed bed and heats the powder to the heat treatment temperature tn a short period of ttme. The powder rematns in the chamber for a ttme sufftc1ent to obtatn the beta convers10n and then the converted powder ts collected and conve~ved out of the chamber to cool down.
Heat1ng methods such as th1s are amenable to etther contlnucus or batch operat10n.
Other var1at10ns can be made to the above descrtbed process and rematn w1thtn the scope of the present tnventton. The spec1ftc descr1pt10ns g1ven above relat1ng to the method of th1s 1nvent~on are for illustrattve purposes and are not tntended to 11m1t the scope of the 1nventton as clatmed.
;; .
~ ~.. - ,... ,.: ,: ,; .- : : .
!: ', :: . :': : :: -' ` .: . .
:.' ' :,' . : :.
~..... ` : :. .
Y ` ' , :, .:
r
Claims (16)
1. An improved process for producing beta manganese dioxide comprising feeding particulate gamma manganese dioxide into a chamber, continuously changing the relative positions of the MnO2 particles in said chamber while heating the gamma manganese dioxide to at least 450°C, holding the temperature of themanganese dioxide at at least 450°C for a time to convert a majority of the manganese dioxide to a beta crystal phase without forming detrimental amounts of lower oxides, and removing the heat treated manganese dioxide from the chamber.
2. The process of claim 1 wherein the manganese dioxide is heated to at least 450°C in up to one hour and holding the temperature of the average manganese dioxide particle at a temperature of at least 450°C for up to one hour.
3. The process of claim 1 wherein the gamma manganese dioxide is heated to at least 465°C for up to one hour, and holding the temperature of the manganese dioxide at at least 465°C for up to 30 minutes in order to convert a majority of the manganese dioxide to a beta phase.
4. The process of claim 2 wherein the manganese dioxide is continuously fed through the chamber.
5. The process of claim 4 wherein the gamma manganese dioxide is fed into the chamber at a rate of between 0.1 and 3.0 pounds per minute.
6. The process of claim 3 wherein the gamma manganese dioxide is preheated to up to 300°C before feeding said manganese dioxide into the chamber.
7. The process of claim 3 wherein the heat treated manganese dioxide is 60-90%
beta crystal phase.
beta crystal phase.
8. An improved process for producing manganese dioxide cathodes suitable for use in non-aqueous cells comprising continuously feeding gamma manganese dioxide into a rotary tube furnace heated to at least 450°C, rotating thetube, heating the manganese dioxide to at least 450°C during a period of up to one hour in a first portion of the tube, holding the temperature of the manganese dioxide at at least 450°C for up to one hour in a second portion of the tube in order to convert a majority of the manganese dioxide to a beta phase, cooling the manganese dioxide in a third portion of the tube, and collecting the heat treated manganese dioxide.
9. The process of claim 8 wherein the manganese dioxide is heated to at least 465°C for up to one hour in the first portion of the tube and the manganese dioxide is held at at least 465°C for up to 30 minutes in the second portion of the tube.
10. The process of claim 9 wherein the manganese dioxide is held at at least 465°C for up to 15 minutes.
11. The process of claim 8 wherein between about 60% and 90% of the gamma manganese dioxide is converted to the beta crystal phase.
12. The process of claim 8 wherein between about 65% and 85% of the gamma manganese dioxide is converted to the beta crystal phase.
13. The process of claim 9 wherein the manganese dioxide is fed into the rotary tube furnace at between 0.1 and 3.0 pounds per minute.
14. The process of claim 9 wherein the manganese dioxide is preheated to a temperature up to 300°C before it is fed into the rotary tube furnace.
15. The process of claim 11 further comprising forming an admixture of the heat treated manganese dioxide, a conductive agent, and a binder; coating the admixture onto an expanded metal grid; compressing the coated grid between rollers to form a cathode; and heating the cathode between 150° and 300°C
to remove absorbed moisture.
to remove absorbed moisture.
16. The process of claim 15 wherein the conductive agent is selected from carbon black, acetylene black, and mixtures thereof and the binder is polytetrafluoroethylene.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/211,309 US4921689A (en) | 1988-06-24 | 1988-06-24 | Process for producing beta manganese dioxide |
| EP89305869A EP0348083B1 (en) | 1988-06-24 | 1989-06-09 | Process for producing beta manganese dioxide |
| AU36579/89A AU610471B2 (en) | 1988-06-24 | 1989-06-19 | Process for producing beta manganese dioxide |
| CA000603550A CA1331834C (en) | 1988-06-24 | 1989-06-21 | Process for producing beta manganese dioxide |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/211,309 US4921689A (en) | 1988-06-24 | 1988-06-24 | Process for producing beta manganese dioxide |
| CA000603550A CA1331834C (en) | 1988-06-24 | 1989-06-21 | Process for producing beta manganese dioxide |
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| Publication Number | Publication Date |
|---|---|
| CA1331834C true CA1331834C (en) | 1994-09-06 |
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|---|---|---|---|
| CA000603550A Expired - Fee Related CA1331834C (en) | 1988-06-24 | 1989-06-21 | Process for producing beta manganese dioxide |
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| Country | Link |
|---|---|
| US (1) | US4921689A (en) |
| EP (1) | EP0348083B1 (en) |
| AU (1) | AU610471B2 (en) |
| CA (1) | CA1331834C (en) |
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| JP3342769B2 (en) * | 1994-03-31 | 2002-11-11 | 三井金属鉱業株式会社 | Manganese dioxide for lithium primary battery and method for producing the same |
| DE19520874A1 (en) * | 1994-12-15 | 1996-06-20 | Basf Magnetics Gmbh | Spinels containing lithium and manganese (III / IV) |
| US6863984B2 (en) | 1995-01-20 | 2005-03-08 | Engelhard Corporation | Catalyst and adsorption compositions having improved adhesion characteristics |
| US20030166466A1 (en) * | 1995-01-20 | 2003-09-04 | Hoke Jeffrey B. | Catalyst and adsorption compositions having improved adhesion characteristics |
| US6200542B1 (en) | 1995-01-20 | 2001-03-13 | Engelhard Corporation | Method and apparatus for treating the atmosphere |
| US6214303B1 (en) | 1995-01-20 | 2001-04-10 | Engelhard Corporation | Method and apparatus for treating the atmosphere |
| US20020018742A1 (en) * | 1995-01-20 | 2002-02-14 | Engelhard Corporation | Method and apparatus for treating the atmosphere |
| US6517899B1 (en) | 1995-01-20 | 2003-02-11 | Engelhard Corporation | Catalyst and adsorption compositions having adhesion characteristics |
| DE69620740T2 (en) | 1995-01-20 | 2002-08-22 | Engelhard Corp | DEVICE FOR REMOVING POLLUTANTS FROM AMBIENT AIR IN THE BONNET OF A VEHICLE |
| US6818254B1 (en) | 1995-01-20 | 2004-11-16 | Engelhard Corporation | Stable slurries of catalytically active materials |
| US5698176A (en) * | 1995-06-07 | 1997-12-16 | Duracell, Inc. | Manganese dioxide for lithium batteries |
| US5997831A (en) * | 1996-07-12 | 1999-12-07 | Engelhard Corporation | Method of catalytically treating the atmosphere and heat exchange devices produced thereby |
| JPH11111286A (en) * | 1997-09-30 | 1999-04-23 | Mitsui Mining & Smelting Co Ltd | Manufacture of positive electrode material for lithium secondary battery |
| US6156283A (en) * | 1998-03-23 | 2000-12-05 | Engelhard Corporation | Hydrophobic catalytic materials and method of forming the same |
| US6190800B1 (en) | 1998-05-11 | 2001-02-20 | The Gillette Company | Lithiated manganese dioxide |
| US6610263B2 (en) | 2000-08-01 | 2003-08-26 | Enviroscrub Technologies Corporation | System and process for removal of pollutants from a gas stream |
| US7232782B2 (en) * | 2002-03-06 | 2007-06-19 | Enviroscrub Technologies Corp. | Regeneration, pretreatment and precipitation of oxides of manganese |
| US20030059460A1 (en) * | 2001-09-27 | 2003-03-27 | Yasuhiko Tabata | Hybrid material for regeneration of living body tissue |
| KR20040090962A (en) * | 2001-12-21 | 2004-10-27 | 엔바이로스크럽 테크놀러지스 코퍼레이션 | Pretreatment and regeneration of oxides of manganese |
| BRPI0407007A (en) * | 2003-01-28 | 2006-01-10 | Enviroscrub Technologies Corp | Method and system for fast and adaptable processing of manganese oxides and integrated sorbent processing and pollution control system |
| US7488464B2 (en) * | 2003-07-31 | 2009-02-10 | Enviroscrub Technologies Corporation | Metal oxide processing methods and systems |
| US8137842B2 (en) * | 2004-01-22 | 2012-03-20 | The Gillette Company | Battery cathodes |
| US8003254B2 (en) * | 2004-01-22 | 2011-08-23 | The Gillette Company | Battery cathodes |
| US20050164085A1 (en) * | 2004-01-22 | 2005-07-28 | Bofinger Todd E. | Cathode material for lithium battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3301634A (en) * | 1963-07-09 | 1967-01-31 | Harry C Fuller | Process for decomposing manganese sulfate to form manganous oxide and sulfur dioxide |
| JPS5342325A (en) * | 1976-09-29 | 1978-04-17 | Sanyo Electric Co | Method of making cathode of nonnaqueous battery |
| DE2835976C3 (en) * | 1978-08-17 | 1982-05-19 | Hitachi Chemical Co., Ltd. | Galvanic element |
| JPS6041829B2 (en) * | 1979-01-06 | 1985-09-19 | 株式会社日立製作所 | Manufacturing method of positive electrode for non-aqueous electrolyte battery |
| DE3123100A1 (en) * | 1981-06-11 | 1983-01-05 | Varta Batterie Ag, 3000 Hannover | MANGANE DIOXIDE ELECTRODE FOR LITHIUM BATTERIES |
| JPS60189163A (en) * | 1984-03-06 | 1985-09-26 | Sony Corp | Lithium-manganese dioxide battery |
| US4662065A (en) * | 1986-05-22 | 1987-05-05 | Battery Engineering, Inc. | Method for dehydrating manganese dioxide |
-
1988
- 1988-06-24 US US07/211,309 patent/US4921689A/en not_active Expired - Lifetime
-
1989
- 1989-06-09 EP EP89305869A patent/EP0348083B1/en not_active Expired - Lifetime
- 1989-06-19 AU AU36579/89A patent/AU610471B2/en not_active Ceased
- 1989-06-21 CA CA000603550A patent/CA1331834C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU610471B2 (en) | 1991-05-16 |
| AU3657989A (en) | 1990-01-04 |
| EP0348083B1 (en) | 1993-09-29 |
| EP0348083A1 (en) | 1989-12-27 |
| US4921689A (en) | 1990-05-01 |
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