According to one embodiment of the present invention, a secondary battery that can be used at a wide range of temperatures and is less likely to be influenced by an environmental temperature is provided. Furthermore, a secondary battery with high safety is provided. An electrolyte obtained by mixing an acyclic ester having high temperature characteristics with a fluorinated carbonic ester at 5 vol. % or higher, preferably 20 vol. % or higher, is used for the purpose of reducing interface resistance between an electrode and an electrolyte, whereby a secondary battery capable of operating at a wide range of temperatures, specifically, at temperatures higher than or equal to −40° C. and lower than or equal to 150° C., preferably higher than or equal to −40° C. and lower than or equal to 85° C. can be achieved.

A lithium-ion battery separator includes a substrate defining inter-particle pores and a zeolite coating on a surface of the substrate. The zeolite coating includes zeolite particles. The zeolite particles are hydrophobic and have an average diameter smaller than an average pore size of inter-particle pores of the substrate, such that some of the zeolite particles are positioned in some of the inter-particle pores. The separator is non-flammable In a lithium-ion battery, the substrate is a first electrode, and a second electrode is in direct contact with the zeolite coating. The lithium-ion battery includes a non-flammable salt-concentrated electrolyte, and the zeolite coating has a high wettability for the electrolyte. The lithium-ion battery is non-flammable.

Disclosed is an electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexaflu-oro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl methyl carbonate (F3EMC), ii) or a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl acetate (F3EA), b) at least one lithium salt, the cation of which is the cation of an alkali metal.

Disclosed is an electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexaflu-oro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl methyl carbonate (F3EMC), ii) or a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl acetate (F3EA), b) at least one lithium salt, the cation of which is the cation of an alkali metal.

Provided is an electrode, including: a collector; and an active material layer formed on the collector, wherein the active material layer contains sulfur-modified polyacrylonitrile and a lithium-titanium oxide, wherein an average secondary particle diameter of the sulfur-modified polyacrylonitrile is larger than an average secondary particle diameter of the lithium-titanium oxide, and wherein a content of the sulfur-modified polyacrylonitrile in the active material layer is from 5 mass % to 85 mass %, and a content of the lithium-titanium oxide in the active material layer is from 5 mass % to 85 mass %.

Provided is an electrode, including: a collector; and an active material layer formed on the collector, wherein the active material layer contains sulfur-modified polyacrylonitrile and a lithium-titanium oxide, wherein an average secondary particle diameter of the sulfur-modified polyacrylonitrile is larger than an average secondary particle diameter of the lithium-titanium oxide, and wherein a content of the sulfur-modified polyacrylonitrile in the active material layer is from 5 mass % to 85 mass %, and a content of the lithium-titanium oxide in the active material layer is from 5 mass % to 85 mass %.

Various implementations of a method of forming an electrochemical cell include providing a first electrode, a second electrode, a separator between the first and second electrodes, and an electrolyte in a cell container. The first electrode can include silicon-dominant electrochemically active material. The silicon-dominant electrochemically active material can include greater than 50% silicon by weight. The method can also include exposing at least a part of the electrochemical cell to CO.sub.2, and forming a solid electrolyte interphase (SEI) layer on the first electrode using the CO.sub.2.

Electrolytes and electrolyte additives for energy storage devices comprising a sulfonate ester compound are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte, and at least one electrolyte additive selected from a sulfonate ester compound.

Provided is a non-aqueous electrolyte secondary battery capable of achieving both load characteristics and cycle characteristics. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolytic solution. The negative electrode includes a negative electrode active material layer including acrylonitrile-styrene-butadiene rubber. The non-aqueous electrolytic solution includes a propionic acid ester, a halogenated cyclic carbonic acid ester, and at least one of predetermined cyclic sulfuric acid anhydrides. A content of the acrylonitrile-styrene-butadiene rubber in the negative electrode active material layer is 0.5 mass% or more and 2.0 mass% or less.

Provided is a non-aqueous electrolyte secondary battery capable of achieving both load characteristics and cycle characteristics. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolytic solution. The negative electrode includes a negative electrode active material layer including acrylonitrile-styrene-butadiene rubber. The non-aqueous electrolytic solution includes a propionic acid ester, a halogenated cyclic carbonic acid ester, and at least one of predetermined cyclic sulfuric acid anhydrides. A content of the acrylonitrile-styrene-butadiene rubber in the negative electrode active material layer is 0.5 mass% or more and 2.0 mass% or less.