Compositions – Electrically conductive or emissive compositions – Elemental carbon containing
Reexamination Certificate
2001-10-24
2004-01-06
Gupta, Yogendra N. (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Elemental carbon containing
C252S500000, C252S506000, C252S518100, C429S142000, C429S303000, C429S304000, C429S309000, C429S319000, C523S500000, C523S515000
Reexamination Certificate
active
06673273
ABSTRACT:
BACKGROUND
The present invention relates to electrolyte compositions and electrochemical cells for use in alkali metal polymer batteries, particularly lithium polymer batteries. Lithium polymer batteries typically include a lithium metal negative electrode (anode), or other suitable lithium-containing substance such as lithium metal alloys or lithium metal oxides, a metal oxide positive electrode (e.g., lithium vanadium oxide), and a solid polymer electrolyte. During operation, lithium is oxidized at the anode and lithium ions move into the electrolyte and to the cathode. When the battery is charged, lithium ions are reduced (plated) at the anode. This is accompanied by movement of lithium ions into the electrolyte from the cathode.
Solid electrolytes include ionically conducting polymers. The solid polymer electrolyte is typically poly(ethylene oxide) (PEO) based, complexed with a lithium salt. Such batteries possess high-energy storage capacity and rechargeability. PEO-based electrolytes are generally useful at temperatures above the melting point of the PEO-based salt complex. PEO itself has a melting point of 65° C. but this may be lowered by copolymerization and salt inclusion. The need to use PEO-based electrolytes at higher temperatures is primarily due to their high degree of crystallinity and the fact that lithium ion conduction takes place only through the amorphous region. This temperature dependence of the conductivity of PEO-based polymer electrolytes results in them being primarily used above ambient temperature. In lithium polymer batteries the temperature is often maintained and controlled at about 40° C. to about 80° C.
However, at temperatures above 65° C., uncrosslinked PEO undergoes flow and creep. This can result in the loss of mechanical strength, depriving the polymer electrolyte the ability to prevent cell shorting due to the formation of lithium dendrites. Also, PEO chains can migrate to the lithium anode surface and the free hydroxyl groups on the PEO can react with a lithium metal surface irreversibly. This can cause the interfacial resistance to increase and result in failures in battery cycling at 80° C. Thus, what is needed is an electrolyte that has the advantages of PEO, but fewer deficiencies.
SUMMARY
The present invention provides solid polymer electrolyte compositions. In one embodiment, the solid polymer electrolyte composition includes: a crosslinked solid ionically conductive polymer having urethane groups, urea groups, thiocarbamate groups, or combinations thereof; inorganic oxide particles; and a salt; with the proviso that at 20° C. there is less than about 1 wt-% liquid present in the electrolyte composition; and wherein the solid polymer electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 60° C. Preferably, and significantly, the inorganic oxide particles are substantially covalently bonded to either the polymer or other inorganic oxide particles (i.e., each other) through urethane groups, urea groups, thiocarbamate groups, or combinations thereof.
In another embodiment, the present invention provides a solid polymer electrolyte composition that includes: a crosslinked solid ionically conductive polymer having urethane groups, urea groups, thiocarbamate groups, or combinations thereof; nanoparticles, wherein at least 50% of the nanoparticles have a smallest dimension less than about 50 nm; and a salt; with the proviso that at 20° C. there is less than about 1 wt-% liquid present in the electrolyte composition; and wherein the solid polymer electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at 60° C.
In yet another embodiment, the present invention provides a solid polymer electrolyte composition that includes: a crosslinked solid ionically conductive polymer that includes a poly(alkylene oxide) polymer having urethane groups; at least about 0.5 wt-% hydroxyl-functional inorganic oxide particles; and a salt; with the proviso that at 20° C. there is less than about 1 wt-% liquid present in the electrolyte composition; and wherein the solid polymer electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 60° C.
In another embodiment, the present invention provides a solid polymer electrolyte composition that includes: a crosslinked solid ionically conductive polymer that includes a poly(alkylene oxide) polymer having urethane groups, wherein the solid ionically conductive polymer is prepared from a polyisocyanate, a poly(alkylene oxide) polymer having an equivalent weight of about 1,000 to about 100,000, and a poly(alkylene oxide) polymer having an equivalent weight of about 150,000 to about 500,000; at least about 3 wt-% hydroxy-functional inorganic oxide particles; and a lithium salt; with the proviso that at 20° C. there is less than about 1 wt-% liquid present in the electrolyte composition; and wherein the solid polymer electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 60° C.
In still another embodiment, the present invention provides a solid polymer electrolyte composition that includes: a crosslinked solid ionically conductive polymer prepared from a polymer of the formula A-(alkylene oxide)
n
-A, wherein A is —OH, —NH
2
, or —SH, and n is at least about 10, and a molar excess of a compound of the formula Z—R—T, wherein T is an organic group having a vinyl group, R is a divalent organic group, and Z is a functional group capable of reacting with —OH, —NH
2
, or —SH; at least about 0.5 wt-% hydroxyl-functional inorganic oxide particles; and a lithium salt; with the proviso that at 20° C. there is less than about 1 wt-% liquid present in the electrolyte composition; and wherein the solid polymer electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 60° C.
The present invention also provides gel electrolyte compositions. In one embodiment, a gel electrolyte composition includes: a crosslinked solid ionically conductive polymer having urethane groups, urea groups, thiocarbamate groups, or combinations thereof; inorganic oxide particles; and a liquid electrolyte including a liquid at 20° C. and a salt; with the proviso that the gel electrolyte composition is nonswellable; and wherein the gel electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 20° C.
In another embodiment, a gel electrolyte composition includes: a crosslinked solid ionically conductive polymer having urethane groups, urea groups, thiocarbamate groups, or combinations thereof; nanoparticles, wherein at least 50% of the nanoparticles have a smallest dimension less than about 50 nm; and a liquid electrolyte including a liquid at 20° C. and a salt; with the proviso that the gel electrolyte composition is nonswellable; and wherein the gel electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 20° C.
In yet another embodiment, a gel electrolyte composition includes: a crosslinked solid ionically conductive polymer that includes a poly(alkylene oxide) polymer having urethane groups; at least about 0.5 wt-% hydroxyl-functional inorganic oxide particles; and a liquid electrolyte including a liquid at 20° C. and a salt; with the proviso that the gel electrolyte composition is nonswellable; and wherein the gel electrolyte composition has an ionic conductivity of at least about 1×10
−4
S/cm at about 20° C.
In another embodiment, a gel electrolyte composition includes: a crosslinked solid ionically conductive polymer that includes a poly(alkylene oxide) polymer having urethane groups, wherein the solid ionically conductive polymer is prepared from a poly(alkylene oxide) polymer having a weight average molecular weight of about 1,000 to about 20,000 and a polyisocyanate; hydroxyl-functional inorganic oxide particles; and a liquid electrolyte including a liquid at 20° C. and a salt; with the proviso that the gel electrolyte composition
Arudi Ravindra L.
Ba Le Dinh
Scanlan Jerome Edward
3M Innovative Properties Company
Gupta Yogendra N.
Mueting Raasch & Gebhardt, P.A.
Pastirik Daniel R.
Vijayakumar Kallambella M
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