A novel wound electrode assembly for a lithium oxyhalide electrochemical cell is described. The electrode assembly comprises an elongate cathode of an electrochemically non-active but electrically conductive carbonaceous material disposed between an inner elongate portion and an outer elongate portion of a unitary lithium anode. That way, lithium faces the entire length of the opposed major sides of the cathode. This inner anode portion/cathode/outer anode portion configuration is rolled into a wound-shaped electrode assembly that is housed inside a cylindrically-shaped casing. A cylindrically-shaped sheet-type spring centered in the electrode assembly presses outwardly to limit axial movement of the electrode assembly. In one embodiment, all the non-active components, except for the cathode current collector which is nickel, are made of stainless-steel. This provides the cell with a low magnetic signature without adversely affecting the cell's high-rate capability.

Provided is a nonaqueous electrolytic solution having an excellent capacity retention rate and an excellent output retention rate during cycles. The nonaqueous electrolytic solution includes a nonaqueous solvent; a hexafluorophosphate (A); a compound (B) represented by the following formula (1) in which an arbitrary hydrogen atom bonded to a carbon atom may be substituted with a fluorine atom; and at least one salt (C) selected from the group consisting of fluorophosphates other than the hexafluorophosphate (A), fluorosulfonates, imide salts represented by MN(SO.sub.2F).sub.2, wherein M represents an alkali metal, and oxalate salts.

##STR00001##

An air battery includes a positive electrode using oxygen as a positive electrode active material, a negative electrode containing metal as a negative electrode active material, and a sheet layer interposed between the positive electrode and the negative electrode. The positive electrode is formed in a solid state containing an electrolyte for ionizing the metal of the negative electrode and conductive particles. The sheet layer is made of a material containing no electrolytic solution and exhibiting hygroscopic properties. The sheet layer allows the electrolyte contained in the positive electrode to penetrate toward the negative electrode, and allows metal ions generated in the negative electrode to penetrate toward the positive electrode.

Improved negative electrodes can comprise a silicon based active material blended with graphite to provide more stable cycling at high energy densities. In some embodiments, the negative electrodes comprise a blend of polyimide binder mixed with a more elastic polymer binder with a nanoscale carbon conductive additive. Electrolytes have been formulated that provide for extended cycling of cells incorporating a mixture of a silicon-oxide based active material with graphite active material in negative electrodes that can be matched with positive electrodes comprising nickel rich lithium nickel manganese cobalt oxides to cells with unprecedented cycling properties for large capacity cell based on a silicon negative electrode active material.

An object is to provide a nonaqueous electrolyte and a nonaqueous-electrolyte secondary battery which have excellent discharge load characteristics and are excellent in high-temperature storability, cycle characteristics, high capacity, continuous-charge characteristics, storability, gas evolution inhibition during continuous charge, high-current-density charge/discharge characteristics, discharge load characteristics, etc. The object has been accomplished with a nonaqueous electrolyte which comprises: a monofluorophosphate and/or a difluorophosphate; and further a compound having a specific chemical structure or specific properties.

An object is to provide a nonaqueous electrolyte and a nonaqueous-electrolyte secondary battery which have excellent discharge load characteristics and are excellent in high-temperature storability, cycle characteristics, high capacity, continuous-charge characteristics, storability, gas evolution inhibition during continuous charge, high-current-density charge/discharge characteristics, discharge load characteristics, etc. The object has been accomplished with a nonaqueous electrolyte which comprises: a monofluorophosphate and/or a difluorophosphate; and further a compound having a specific chemical structure or specific properties.

An electrolyte for a lithium-ion battery which includes lithium hexafluorophosphate and lithium 2-pentafluoroethoxy-1,1,2,2-tetrafluoroethanesulfonate. A lithium-ion battery which includes an electrolyte containing lithium hexafluorophosphate and lithium 2-pentafluoroethoxy-1,1,2,2-tetrafluoroethanesulfonate. A motor vehicle which uses a lithium-ion battery having electrolytes containing lithium hexafluorophosphate and lithium 2-pentafluoroethoxy-1,1,2,2-tetrafluoroethanesulfonate. The electrolyte can increase the service life of the lithium-ion battery.

An electrolyte for a rechargeable lithium battery includes an organic solvent including C3 to C5 alkyl propionate, and the electrolyte further includes a lithium salt and a compound represented by Chemical Formula 1, ##STR00001## wherein, in Chemical Formula 1, k, l, and m are independently integers of 0 to 20, k, l, and m are selected, so that Chemical Formula 1 has an asymmetric structure, n is an integer of 1 to 7, and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are independently hydrogen, an alkyl group, an alkoxy group, or a fluoroalkyl group.

An electrolyte composition and a metal-ion battery employing the same are provided. The electrolyte composition includes a metal halide, a solvent, and an additive. The solvent is an ionic liquid or organic solvent. The molar ratio of the metal halide to the solvent is from 1:1 to 2.2:1. The amount of additive is from 1 wt % to 25 wt %, based on the total weight of the metal halide and the solvent. The additive is monochloroethane, trichlorethylene, dichloroethane, trichloroethane, phosphorus trichloride, phosphorus pentachloride, methyl pyidine, methyl nicotinate, or a combination thereof.

An electrolyte composition and an electrochemical cell that includes the electrolyte composition are included. The electrolyte composition includes: at least one aprotic organic solvent; at least one conducting salt; methylphosphonoyloxymethane; and optionally one or more additives. The use of methylphosphonoyloxymethane in an electrolyte composition for electrochemical cells is also included.