CA1199365A - Method of improving the cycling efficiency of a lithium aluminum alloy anode - Google Patents
Method of improving the cycling efficiency of a lithium aluminum alloy anodeInfo
- Publication number
- CA1199365A CA1199365A CA000441107A CA441107A CA1199365A CA 1199365 A CA1199365 A CA 1199365A CA 000441107 A CA000441107 A CA 000441107A CA 441107 A CA441107 A CA 441107A CA 1199365 A CA1199365 A CA 1199365A
- Authority
- CA
- Canada
- Prior art keywords
- anode
- lithium
- electrolyte
- cathode
- separator
- 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
Links
- 238000000034 method Methods 0.000 title claims abstract description 19
- 230000001351 cycling effect Effects 0.000 title claims abstract description 18
- JFBZPFYRPYOZCQ-UHFFFAOYSA-N [Li].[Al] Chemical compound [Li].[Al] JFBZPFYRPYOZCQ-UHFFFAOYSA-N 0.000 title claims abstract description 16
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 15
- 238000011065 in-situ storage Methods 0.000 claims abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 19
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 17
- 239000003792 electrolyte Substances 0.000 claims description 14
- 229910052744 lithium Inorganic materials 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 13
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 11
- 239000000758 substrate Substances 0.000 claims description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 6
- 239000004743 Polypropylene Substances 0.000 claims description 6
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 6
- -1 lithium hexafluoro-arsenate Chemical compound 0.000 claims description 5
- 229910003002 lithium salt Inorganic materials 0.000 claims description 5
- 159000000002 lithium salts Chemical class 0.000 claims description 5
- 239000005486 organic electrolyte Substances 0.000 claims description 5
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 239000011244 liquid electrolyte Substances 0.000 claims description 4
- 229910001540 lithium hexafluoroarsenate(V) Inorganic materials 0.000 claims description 4
- HSZCZNFXUDYRKD-UHFFFAOYSA-M lithium iodide Chemical compound [Li+].[I-] HSZCZNFXUDYRKD-UHFFFAOYSA-M 0.000 claims description 4
- 239000003658 microfiber Substances 0.000 claims description 4
- 230000005012 migration Effects 0.000 claims description 4
- 238000013508 migration Methods 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- 229920001410 Microfiber Polymers 0.000 claims description 3
- 239000010405 anode material Substances 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 claims description 2
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 229960001760 dimethyl sulfoxide Drugs 0.000 claims description 2
- 238000009713 electroplating Methods 0.000 claims description 2
- 230000006872 improvement Effects 0.000 claims description 2
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 claims description 2
- 239000012047 saturated solution Substances 0.000 claims description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 2
- CFJRPNFOLVDFMJ-UHFFFAOYSA-N titanium disulfide Chemical compound S=[Ti]=S CFJRPNFOLVDFMJ-UHFFFAOYSA-N 0.000 claims description 2
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 claims 3
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 claims 2
- 229910001935 vanadium oxide Inorganic materials 0.000 claims 2
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims 1
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 239000003960 organic solvent Substances 0.000 claims 1
- 235000010210 aluminium Nutrition 0.000 description 15
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 229910010199 LiAl Inorganic materials 0.000 description 6
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 2
- 229910007857 Li-Al Inorganic materials 0.000 description 2
- 229910008447 Li—Al Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 229910001148 Al-Li alloy Inorganic materials 0.000 description 1
- DJHGAFSJWGLOIV-UHFFFAOYSA-K Arsenate3- Chemical compound [O-][As]([O-])([O-])=O DJHGAFSJWGLOIV-UHFFFAOYSA-K 0.000 description 1
- XUKUURHRXDUEBC-KAYWLYCHSA-N Atorvastatin Chemical compound C=1C=CC=CC=1C1=C(C=2C=CC(F)=CC=2)N(CC[C@@H](O)C[C@@H](O)CC(O)=O)C(C(C)C)=C1C(=O)NC1=CC=CC=C1 XUKUURHRXDUEBC-KAYWLYCHSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910010808 Li2Al Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 101100409194 Rattus norvegicus Ppargc1b gene Proteins 0.000 description 1
- 241000428533 Rhis Species 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229940000489 arsenate Drugs 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- FTGZPVKRMCXHDZ-UHFFFAOYSA-N dioxovanadiooxy(dioxo)vanadium;dioxovanadium Chemical compound O=[V]=O.O=[V]=O.O=[V]=O.O=[V]=O.O=[V](=O)O[V](=O)=O FTGZPVKRMCXHDZ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000003455 independent Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000007775 late Effects 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000003334 potential effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- BALXUFOVQVENIU-KXNXZCPBSA-N pseudoephedrine hydrochloride Chemical compound [H+].[Cl-].CN[C@@H](C)[C@@H](O)C1=CC=CC=C1 BALXUFOVQVENIU-KXNXZCPBSA-N 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/0438—Processes of manufacture in general by electrochemical processing
- H01M4/0459—Electrochemical doping, intercalation, occlusion or alloying
- H01M4/0461—Electrochemical alloying
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
- H01M4/662—Alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
-
- 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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/40—Alloys based on alkali metals
- H01M4/405—Alloys based on lithium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
Abstract
Abstract of the Disclosure The invention disclosed is a method of improving the cycling efficiency of a lithium aluminum alloy anode in an electrochemical cell which comprises compressing the anode in situ at a pressure of 1.0 to 2,5 kg/cm2.
Description
'rhis invention r~lates to -the rechar~Jeability of secondary electrochemical cells and in part:icular l~.o -the irnproved cyclinq efficiency of a lithi.um aluminum al].oy elec-trode opera-ting in an organic electrolyte.
It i.s well known -that there is considerable di.fficulty in obtaining high cycli.nq e:Eficiencies for lithium anodes in secondary li-thi.um batteri~s b~cause of the ~ndri-tic nature o:E
the e]ectrodeposi-ted metal. For this reason, considerable interest is evident in the recen-t literature in the lithium-aluminum elec~
trode as an alternative -to pure lithium in room -tempera-ture cells.
Most fundamental work involving -the Li-Al systerrl has been carried out at higher temperatures in connec-tion wi-th the use of the alloy electrode in molten sal-t systems. Phase diayrams and structural and thermodynamic data have been reported in the literature~ Lithi~lm ~orms a solid solution with aluminum with up to ~7 atomic percent (a/o) Li (the ~-phase). For higher lithium content, the ~ -phase, LiAl is formed; however, this phase is nonstoichiometric, having compositions in the rancJe 47 to at leas-t 56 a/o Li. At higher lithium concentra-tions, compounds suc~ as Li3A12, Li2Al, and LigA14 are formed.
In the case of l,iAl/~l electrode operating in an organic elec-trolyte, four steps can be distinguished in the reduction process: (a) migration of Li ions in -the passivation layer, (b) charge transfer, (c) dif-fusion of Li in ~-LiAl, and (d) reaction of Li and Al. Because the mobility of Al in ~-LiA]
is negligible in compari.son w.:ith the mob:i.lity of I.:i, the LiAl deposi-t i.s never dend:ri-tic, and thereore, rnuch .less vulnerable -to corrosion. I-lowever, e~en i~ the ~olution reacts eEficient~.y with -the qrain boundaries of -the LiA:L alloy, one of -the products, ~ \
3;3~
namel.y ~1, may p:rov1cl~! goocl elc~ctr:Lcal contac-t between th~
grains. Moreove:r, formation of l.iA.l. occurs ~t a poten-tial rnore positive than the potentia] necessary for deposition o:E metallic lithium. These dif.Eerences explain why the cyclincJ efficiency o-E
the Li~l/Al electrode is relatively hiyh and practically indepen-dent of the natuxe of -the organlc elect:ro]yte. In addition, LiAl is more thermodynamically s-ta~le than I,i.
I-t is thus reasonable to assume tha-t the cycling efficiency of the Li-Al al.loy elec~rode is much more determined by -the properties of the Li-Al alloy i-tself.
It has been found that the cycling efficiency of the lithium-aluminum alloy electrode is limited by cracking of the lithium-aluminum layer formed on an a].uminum substrate duri.ny cycling of the electrode. The cracking occurs because of the fact that -the molar volume of the alloy is greater than that of alumi-num alone. The cracking is accompanied by isolation of active grains of alloy ma-terial which even-tually fall off -the electrode thereby significantly reducing cycling efficiency.
It is thus an o~ject of -the invention to improve the cycliny efficiency of a. lithium-aluminum alloy anode operating in an organic electrolyte at room tempera-ture.
It is another object of the invention -to provide an improved method for making a lithium-aluminum alloy anode for use in an electrochemical cell which employs a suitable organic liquid elec-trolyte and a cathode~
Accordiny to -the invention, a method of improving the cycling efficiency of a lithium alum:inum alloy anode opera-ting in a suita~le oryanic liquid elec-trolyte in an e]ectrochemical cell is provided, which rnethod compri.ses compress:iny -the anode in situ at a pressure of 1.0 to 2.5 kg~cm~
L,~
The li-thium-aluminum alloy anodes are typica:LI.y formed by electroplat.inq lithium on an al.umin~ml anode substra-te from a suitable organic electroly-te solutlon con-tai.ning a suitabl.e lithium salt. More spe~i:Eically, lit~ m aluminum a].loy is most effectively formed by electropla-tlng l:i.thium on aluminum from a non-aqueous solution con-ta:i.ning a lithium sal-t; for exampl.e, from a propylene carbonate sol.ution containi.ng 1 M lithi~lm bromide~
On the basis of our s-tudi.es, aluminum containing a small amount of i.ron~ magnesium, or silicon is superior with respect to ul-tra-pure aluminum. For ins-tance, aluminum foil and sheeting available for household use normally contains iron and other impurities.
Ideally, only about 50% of the original aluminum should be conver--ted to the alloy so that -the resul-ting electrode remains mechani-cally stable. If the fraction converted -to alloy is significantly less, the energy density of the battery sys-tern is reduced, and the capacity on storage can drop due to conversion of the almost stoichiometric ~-LiAl to -the ~-alloy in which the lithium concen-tration and mobility are much less. The optimum form of the aluminum is probably foil with a thickness of 0.075 mm (mass =
20 mg cm 2) con-taining lithlum deposited with total charge of 18C cm 2 on each side. Such an electrode can be charged or dis-charged with a maximum curren-t densi-ty of about 10mA cm 2.
Thus~ an improved method of makinq a lithium-aluminum alloy anode for use in an electrochem.ical cell employing a suitable organic liquid electrolyte and a cathode is also con-templa-ted, said method comprising electroplating lithiwn on an alumi.num anode substrate from said organic ].iquid electrolyte containing a Sl1it-able lithium salt, the improvement comprlsing compressiny the anode in situ a-t a pressure of 1.0 to 2~5 kg/cm2.
3~ 5 Compression oE the anode provides good e]ectrical contac~ be-tween lithium~aluminum grains forrned on the ano~e substrate, and minimizes -their tendency to separate frorn the aluminum substrate to mechanically s-tabilize the anode struc-tureO
Compression of the anode is eEfected in situ in an electrochemical cell by means of a suitable separator which is inert with respect to the lithium-a:LIlminum alloy anode, the oxganic electrolyte and the cathode. Further, the separator is of a suitable material which is sufficierltly porous -to provide for access of electrolyte to the anode to permit ionic conduc-tion while pxeven-ting migration of the anode material.
The separator material should also be wet-table by -the electrolyte.
Suitable separator ma-terials include porous polypropy-lene materials and glass microfibre materials.
Referring ayain -to the pressure which is applled to the anode in situ via a separator, if -the pressure is too low, -the separator is not effective in retaining granules of the lithium-aluminum alloy formed on the aluminum substrate during cycling which may otherwise separa-te from the substrate. If -the pressure is too high, the porosi-ty of the separator could be reduced, resulting in higher resistance in the electrolyte. A pressure range of 1.0 to 2.5 Kg/cm2 is thus contemplated.
Suitable organic electrolytes for use in electrochemical systems described herein include propylene carbonate, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxye-thane, dimethyl sulphoxide and combinations thereof.
The electrolyte further contains a suitable lithium salt such as lithiurn bromide, lithium iodide, lithium hexafluoro~
arsenate, li-thium perc~llora-te and combinations -thereof to provlde -a 0.5 molar to saturated solution in t:he electroly-te. In the case of LiASF6, saturated ls about 3.5 molar.
The cathode may ~e an intercallatior, materla] such as vanadium oxide (V6O13), molybdenum disulphide or titanium disul-phide.
In the drawiny which scrves to illustrate the embodi-ments of the invention, Figures 1 and 2 are graphs which illus~rate -the effect of pressure applied to the anode surface to improve -the cycling 1~ efficiency of a li-thium-aluminum alloy anode, and Figure 3 is a side eleva-tion in section which illustrates a typical battery sys-tem which employs a compressed lithium-aluminum alloy anode.
Example 1 Figure 1 shows the charge capacity Q of a LiAl electrode (plotted as the logarithm) as a function of -the number of cyc],es N. In the experiment Li was repeatedly transEerred from one Al electrode to a second at a curren-t density of 1 mAcm ~. Both electrodes are made of substantially pure aluminum i.e. 99O999% Al.
The results desicJnated (b) were obtained for free s-tanding elec-trodes in propylene carbonate containing lM LiAsF6. The da-ta designated (a) were obtained for electrodes prc3cnt agains-t a porous polypropylene separator soaked with the same electrolyte~
The electrodes were squeezed together and -tightly wound together wi-th Parafilm, a trademark for a polymeric hydrocarbon film made by Marathon Corporation of ~enasha, Wisconsin. The force used to compress the two electrodes together was about 2.5 ky cm 2. The average cycling efficiency under compression was 97% whereas that for the free standing electrode was only 9~%.
39;~ti5 Example 2 Figure 2 shows -the logaxithm of the charge capacity Q against the number of cycle~ ~or Li~l electro~es ma~le from commercial aluminum suppliecl by Homeshield Industries Itd., Bramalea, Ontario. This material is oE a -thickness of about 0.4 mm and includes about 0.8 %/w Fe, 0.]gO/w Cu, 0.15~/wZn and 2.4%/w Mn as impuri-ties. The electroly-te solution was the same as usecl above. Experiments were carried out with free s~anding electrodes (~), e]ectrodes pressed to the separator with a pressure of about 0.2 kg cm 2(~) and electrodes pressed to the separator with a pressure of 2.5 kg cm 2(~. Compression affects the cycling efficiency only after ~35 cycles. For N ~35, -the average cycling efficiencies are 94% (P = 0), 95gO (P - 0.25 ]cg cm 2) and 98%
(P ~ 2 5 kg cm ).
Similar experiments were conducted using a glass micro-fibre separator and the results were practically identical.
E~ample 3 A simple battery constructed with such a separator pressed against the lithium-aluminum electrode is shown schemati-cally in Figure 3.
Referring to Figure 3, the battery 10 is seen tocomprise an ou-ter casing 12, a lithium-aluminum alloy anode 16, a cathode 14 and a porous separator 18 between the anode and cathode. Biasing means 20 in the form of coil springs 20 and biasing pad 22 serve to compress -the cathode ayainst -the anode.
The springs are selected to provide the appropriate compression i.e. abou-t 2O5 Kg cm . The casing acting to contain e~cess electrolyte which is also absorbed within the porous separa-tor material. The anode surface is thus physically covered by the separator.
.~ L~
The cathode was Inclcle .(':1-0111 an int.ercallatlon material, namely vanadium ox:ide (V~013) obtained by the thermal decomposition ~`, of NH4V03, The battery was comp1ete(l wit:h a ~e~ndall E-]452 separ~
ator soaked with IM LiAsF6 in propyLerle carbona-te. Two cells wi-th capacity limited either by the cathocle or by -the anode were tes-ted.
The result of the cycling experiment conducted with the cell limi-ted by the anode resulted in a cycling e~ficiency for 15 cycles of greater than 99%0 Char~e and discharge cycles for the Li~l/V6013 cell were conducted. A large change in potential was observed during the discharge process. This is typical for an intercalla-tion cathode.
A1-though the arrangement illustrated is a flat plate arrangement, it will be appreciated by those skilled in -the ~rt that a coil arrangement in which the anode, separator and cathode are coiled for use in a standard commercial cylindrical cell is also contemplated. In such an arrangement r it is expected that the elasticity of the separa-tor would provide the appropriate pressure, thus eliminating the need for any addi-tional biaslng means.
It i.s well known -that there is considerable di.fficulty in obtaining high cycli.nq e:Eficiencies for lithium anodes in secondary li-thi.um batteri~s b~cause of the ~ndri-tic nature o:E
the e]ectrodeposi-ted metal. For this reason, considerable interest is evident in the recen-t literature in the lithium-aluminum elec~
trode as an alternative -to pure lithium in room -tempera-ture cells.
Most fundamental work involving -the Li-Al systerrl has been carried out at higher temperatures in connec-tion wi-th the use of the alloy electrode in molten sal-t systems. Phase diayrams and structural and thermodynamic data have been reported in the literature~ Lithi~lm ~orms a solid solution with aluminum with up to ~7 atomic percent (a/o) Li (the ~-phase). For higher lithium content, the ~ -phase, LiAl is formed; however, this phase is nonstoichiometric, having compositions in the rancJe 47 to at leas-t 56 a/o Li. At higher lithium concentra-tions, compounds suc~ as Li3A12, Li2Al, and LigA14 are formed.
In the case of l,iAl/~l electrode operating in an organic elec-trolyte, four steps can be distinguished in the reduction process: (a) migration of Li ions in -the passivation layer, (b) charge transfer, (c) dif-fusion of Li in ~-LiAl, and (d) reaction of Li and Al. Because the mobility of Al in ~-LiA]
is negligible in compari.son w.:ith the mob:i.lity of I.:i, the LiAl deposi-t i.s never dend:ri-tic, and thereore, rnuch .less vulnerable -to corrosion. I-lowever, e~en i~ the ~olution reacts eEficient~.y with -the qrain boundaries of -the LiA:L alloy, one of -the products, ~ \
3;3~
namel.y ~1, may p:rov1cl~! goocl elc~ctr:Lcal contac-t between th~
grains. Moreove:r, formation of l.iA.l. occurs ~t a poten-tial rnore positive than the potentia] necessary for deposition o:E metallic lithium. These dif.Eerences explain why the cyclincJ efficiency o-E
the Li~l/Al electrode is relatively hiyh and practically indepen-dent of the natuxe of -the organlc elect:ro]yte. In addition, LiAl is more thermodynamically s-ta~le than I,i.
I-t is thus reasonable to assume tha-t the cycling efficiency of the Li-Al al.loy elec~rode is much more determined by -the properties of the Li-Al alloy i-tself.
It has been found that the cycling efficiency of the lithium-aluminum alloy electrode is limited by cracking of the lithium-aluminum layer formed on an a].uminum substrate duri.ny cycling of the electrode. The cracking occurs because of the fact that -the molar volume of the alloy is greater than that of alumi-num alone. The cracking is accompanied by isolation of active grains of alloy ma-terial which even-tually fall off -the electrode thereby significantly reducing cycling efficiency.
It is thus an o~ject of -the invention to improve the cycliny efficiency of a. lithium-aluminum alloy anode operating in an organic electrolyte at room tempera-ture.
It is another object of the invention -to provide an improved method for making a lithium-aluminum alloy anode for use in an electrochemical cell which employs a suitable organic liquid elec-trolyte and a cathode~
Accordiny to -the invention, a method of improving the cycling efficiency of a lithium alum:inum alloy anode opera-ting in a suita~le oryanic liquid elec-trolyte in an e]ectrochemical cell is provided, which rnethod compri.ses compress:iny -the anode in situ at a pressure of 1.0 to 2.5 kg~cm~
L,~
The li-thium-aluminum alloy anodes are typica:LI.y formed by electroplat.inq lithium on an al.umin~ml anode substra-te from a suitable organic electroly-te solutlon con-tai.ning a suitabl.e lithium salt. More spe~i:Eically, lit~ m aluminum a].loy is most effectively formed by electropla-tlng l:i.thium on aluminum from a non-aqueous solution con-ta:i.ning a lithium sal-t; for exampl.e, from a propylene carbonate sol.ution containi.ng 1 M lithi~lm bromide~
On the basis of our s-tudi.es, aluminum containing a small amount of i.ron~ magnesium, or silicon is superior with respect to ul-tra-pure aluminum. For ins-tance, aluminum foil and sheeting available for household use normally contains iron and other impurities.
Ideally, only about 50% of the original aluminum should be conver--ted to the alloy so that -the resul-ting electrode remains mechani-cally stable. If the fraction converted -to alloy is significantly less, the energy density of the battery sys-tern is reduced, and the capacity on storage can drop due to conversion of the almost stoichiometric ~-LiAl to -the ~-alloy in which the lithium concen-tration and mobility are much less. The optimum form of the aluminum is probably foil with a thickness of 0.075 mm (mass =
20 mg cm 2) con-taining lithlum deposited with total charge of 18C cm 2 on each side. Such an electrode can be charged or dis-charged with a maximum curren-t densi-ty of about 10mA cm 2.
Thus~ an improved method of makinq a lithium-aluminum alloy anode for use in an electrochem.ical cell employing a suitable organic liquid electrolyte and a cathode is also con-templa-ted, said method comprising electroplating lithiwn on an alumi.num anode substrate from said organic ].iquid electrolyte containing a Sl1it-able lithium salt, the improvement comprlsing compressiny the anode in situ a-t a pressure of 1.0 to 2~5 kg/cm2.
3~ 5 Compression oE the anode provides good e]ectrical contac~ be-tween lithium~aluminum grains forrned on the ano~e substrate, and minimizes -their tendency to separate frorn the aluminum substrate to mechanically s-tabilize the anode struc-tureO
Compression of the anode is eEfected in situ in an electrochemical cell by means of a suitable separator which is inert with respect to the lithium-a:LIlminum alloy anode, the oxganic electrolyte and the cathode. Further, the separator is of a suitable material which is sufficierltly porous -to provide for access of electrolyte to the anode to permit ionic conduc-tion while pxeven-ting migration of the anode material.
The separator material should also be wet-table by -the electrolyte.
Suitable separator ma-terials include porous polypropy-lene materials and glass microfibre materials.
Referring ayain -to the pressure which is applled to the anode in situ via a separator, if -the pressure is too low, -the separator is not effective in retaining granules of the lithium-aluminum alloy formed on the aluminum substrate during cycling which may otherwise separa-te from the substrate. If -the pressure is too high, the porosi-ty of the separator could be reduced, resulting in higher resistance in the electrolyte. A pressure range of 1.0 to 2.5 Kg/cm2 is thus contemplated.
Suitable organic electrolytes for use in electrochemical systems described herein include propylene carbonate, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxye-thane, dimethyl sulphoxide and combinations thereof.
The electrolyte further contains a suitable lithium salt such as lithiurn bromide, lithium iodide, lithium hexafluoro~
arsenate, li-thium perc~llora-te and combinations -thereof to provlde -a 0.5 molar to saturated solution in t:he electroly-te. In the case of LiASF6, saturated ls about 3.5 molar.
The cathode may ~e an intercallatior, materla] such as vanadium oxide (V6O13), molybdenum disulphide or titanium disul-phide.
In the drawiny which scrves to illustrate the embodi-ments of the invention, Figures 1 and 2 are graphs which illus~rate -the effect of pressure applied to the anode surface to improve -the cycling 1~ efficiency of a li-thium-aluminum alloy anode, and Figure 3 is a side eleva-tion in section which illustrates a typical battery sys-tem which employs a compressed lithium-aluminum alloy anode.
Example 1 Figure 1 shows the charge capacity Q of a LiAl electrode (plotted as the logarithm) as a function of -the number of cyc],es N. In the experiment Li was repeatedly transEerred from one Al electrode to a second at a curren-t density of 1 mAcm ~. Both electrodes are made of substantially pure aluminum i.e. 99O999% Al.
The results desicJnated (b) were obtained for free s-tanding elec-trodes in propylene carbonate containing lM LiAsF6. The da-ta designated (a) were obtained for electrodes prc3cnt agains-t a porous polypropylene separator soaked with the same electrolyte~
The electrodes were squeezed together and -tightly wound together wi-th Parafilm, a trademark for a polymeric hydrocarbon film made by Marathon Corporation of ~enasha, Wisconsin. The force used to compress the two electrodes together was about 2.5 ky cm 2. The average cycling efficiency under compression was 97% whereas that for the free standing electrode was only 9~%.
39;~ti5 Example 2 Figure 2 shows -the logaxithm of the charge capacity Q against the number of cycle~ ~or Li~l electro~es ma~le from commercial aluminum suppliecl by Homeshield Industries Itd., Bramalea, Ontario. This material is oE a -thickness of about 0.4 mm and includes about 0.8 %/w Fe, 0.]gO/w Cu, 0.15~/wZn and 2.4%/w Mn as impuri-ties. The electroly-te solution was the same as usecl above. Experiments were carried out with free s~anding electrodes (~), e]ectrodes pressed to the separator with a pressure of about 0.2 kg cm 2(~) and electrodes pressed to the separator with a pressure of 2.5 kg cm 2(~. Compression affects the cycling efficiency only after ~35 cycles. For N ~35, -the average cycling efficiencies are 94% (P = 0), 95gO (P - 0.25 ]cg cm 2) and 98%
(P ~ 2 5 kg cm ).
Similar experiments were conducted using a glass micro-fibre separator and the results were practically identical.
E~ample 3 A simple battery constructed with such a separator pressed against the lithium-aluminum electrode is shown schemati-cally in Figure 3.
Referring to Figure 3, the battery 10 is seen tocomprise an ou-ter casing 12, a lithium-aluminum alloy anode 16, a cathode 14 and a porous separator 18 between the anode and cathode. Biasing means 20 in the form of coil springs 20 and biasing pad 22 serve to compress -the cathode ayainst -the anode.
The springs are selected to provide the appropriate compression i.e. abou-t 2O5 Kg cm . The casing acting to contain e~cess electrolyte which is also absorbed within the porous separa-tor material. The anode surface is thus physically covered by the separator.
.~ L~
The cathode was Inclcle .(':1-0111 an int.ercallatlon material, namely vanadium ox:ide (V~013) obtained by the thermal decomposition ~`, of NH4V03, The battery was comp1ete(l wit:h a ~e~ndall E-]452 separ~
ator soaked with IM LiAsF6 in propyLerle carbona-te. Two cells wi-th capacity limited either by the cathocle or by -the anode were tes-ted.
The result of the cycling experiment conducted with the cell limi-ted by the anode resulted in a cycling e~ficiency for 15 cycles of greater than 99%0 Char~e and discharge cycles for the Li~l/V6013 cell were conducted. A large change in potential was observed during the discharge process. This is typical for an intercalla-tion cathode.
A1-though the arrangement illustrated is a flat plate arrangement, it will be appreciated by those skilled in -the ~rt that a coil arrangement in which the anode, separator and cathode are coiled for use in a standard commercial cylindrical cell is also contemplated. In such an arrangement r it is expected that the elasticity of the separa-tor would provide the appropriate pressure, thus eliminating the need for any addi-tional biaslng means.
Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of improving the cycling efficiency of a lithium-aluminum alloy anode in an electrochemical cell operating at room temperature, said electrochemical cell comprising said anode, a cathode, a porous separator disposed between said anode and cathode and a suitable organic electrolyte, wherein the separator is of a material which is sufficiently porous to permit ionic conduction while preventing migration of the anode material and is selected from the group consisting of a porous poly-propylene and a glass microfiber material, which method comprises cycling the cell while compressing the anode at a pressure of 1.0 to 2.5 kg/cm2 during formation of the anode in situ.
2. A method according to claim 1, wherein the electrolyte includes an organic solvent selected from the group consisting of propylene carbonate, acetonitrile, tetrahydrofuran, 2-methyltetra-hydrofuran, dimethoxyethane, dimethylsulphoxide and combinations thereof, of appropriate battery concentration.
3. A method according to claim 2, wherein the electrolyte further comprises a suitable lithium salt selected from the group consisting of lithium bromide, lithium iodide, lithium hexafluoro-arsenate, lithium perchlorate and combinations thereof to provide a 0.5 molar to saturated solution in the electrolyte.
4. A Method according to claim 3, wherein the cathode is of an intercallation material selected from the group consisting of vanadium oxide (V6013), molybdenum disulphide and titanium disulphide.
5. A method according to claim 1, 3 or 4, wherein the pressure is about 2.5 kg/cm2.
6. A method of improving the cycling efficiency of a lithium-aluminum alloy anode in an electrochemical cell, said electrochemical cell comprising said anode, a vanadium oxide (V6013) cathode, a porous polypropylene separator between said anode and cathode and 1 molar LiAsF6 in propylene carbonate as electrolyte, which method comprises compressing said separator against said anode in situ at a pressure of 1.0 to 2.5 kg/cm2.
7. In a method of making a lithium-aluminum alloy anode for use in an electrochemical cell operating at room temperature, said electrochemical cell comprising said anode, a cathode, a porous separator disposed between said anode and cathode and a suitable organic liquid electrolyte, wherein the separator is of a material which is sufficiently porous to permit ionic conduction while preventing migration of the anode material and is selected from the group consisting of a porous polypropylene and a glass microfiber material, said method comprising electroplating lithium on an aluminum anode substrate from said electrolyte which contains a suitable lithium salt from said lithium-aluminum alloy, the improvement comprising cycling the cell while compressing said anode in situ at a pressure of 1.0 to 2.5 kg/cm2.
8. An improved method according to claim 7, wherein the electrolyte is 1 molar LiAsF6 in propylene carbonate.
9. An improved method according to claim 7 or 8, wherein the separator is of a porous polypropylene material and wherein the pressure is about 2.5 kg/cm2.
10. A method according to claim 7 or 8, wherein the aluminum anode includes 0.8%w Fe, 0.1%/w Cu, 0.15%/w Zn and 2.4%/w of Mn as impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000441107A CA1199365A (en) | 1983-11-14 | 1983-11-14 | Method of improving the cycling efficiency of a lithium aluminum alloy anode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000441107A CA1199365A (en) | 1983-11-14 | 1983-11-14 | Method of improving the cycling efficiency of a lithium aluminum alloy anode |
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| Publication Number | Publication Date |
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| CA1199365A true CA1199365A (en) | 1986-01-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA000441107A Expired CA1199365A (en) | 1983-11-14 | 1983-11-14 | Method of improving the cycling efficiency of a lithium aluminum alloy anode |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0323888A2 (en) * | 1988-01-05 | 1989-07-12 | Alcan International Limited | Battery |
| WO1991000624A1 (en) * | 1989-07-03 | 1991-01-10 | Alcan International Limited | Rechargeable lithium battery |
| WO1996009658A1 (en) * | 1994-09-21 | 1996-03-28 | Aktsionernoe Obschestvo Zakrytogo Tipa 'avtouaz' | Lithium chemical cell |
| US5923525A (en) * | 1993-02-16 | 1999-07-13 | Aktsionernoe Obschestvo "Elit" | Capacitor with double electric layer |
| CN110364686A (en) * | 2019-07-15 | 2019-10-22 | 湖北锂诺新能源科技有限公司 | The production method of button type lithium-manganese battery cathode can be filled |
-
1983
- 1983-11-14 CA CA000441107A patent/CA1199365A/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0323888A2 (en) * | 1988-01-05 | 1989-07-12 | Alcan International Limited | Battery |
| EP0323888A3 (en) * | 1988-01-05 | 1992-05-27 | Alcan International Limited | Battery |
| WO1991000624A1 (en) * | 1989-07-03 | 1991-01-10 | Alcan International Limited | Rechargeable lithium battery |
| US5923525A (en) * | 1993-02-16 | 1999-07-13 | Aktsionernoe Obschestvo "Elit" | Capacitor with double electric layer |
| WO1996009658A1 (en) * | 1994-09-21 | 1996-03-28 | Aktsionernoe Obschestvo Zakrytogo Tipa 'avtouaz' | Lithium chemical cell |
| CN110364686A (en) * | 2019-07-15 | 2019-10-22 | 湖北锂诺新能源科技有限公司 | The production method of button type lithium-manganese battery cathode can be filled |
| CN110364686B (en) * | 2019-07-15 | 2023-01-20 | 湖北锂诺新能源科技有限公司 | Method for manufacturing negative electrode of rechargeable button lithium-manganese battery |
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