This negative electrode for secondary batteries is provided with a negative electrode mixture that contains a negative electrode active material, an additive and a conductive agent. The negative electrode active material contains an Si-containing material; the additive contains an alkali metal sulfate salt; and the conductive agent contains carbon nanotubes. The content of the alkali metal sulfate salt in the negative electrode mixture is from 0.0025% by mass to 0.1% by mass relative to the total mass of the negative electrode active material.

An electrochemical device includes a positive electrode including a positive current collector and a positive electrode material layer supported on the positive current collector, a negative electrode, and an electrolytic solution. The positive electrode material layer includes a conductive polymer, and a surface roughness (Ra) of the positive current collector is in a range from 0.7 μm to 1.7 μm, inclusive.

The present disclosure is directed to providing a binder composition for a non-aqueous secondary battery electrode which can improve the peel strengths of electrodes while increasing the pressibilities of pre-pressing electrode mixed material layers. The presently disclosed binder composition contains a polymer A, wherein the polymer A includes an aliphatic conjugated diene monomer unit and a nitrile-group containing monomer unit, and the polymer A has a THF-insoluble content of 20% by mass or less.

A method for manufacturing an electrode for a secondary battery includes: applying a first layer slurry containing a first binder to a surface of a current collector, applying a second layer slurry containing a second binder on the first layer slurry before the first layer slurry is dried, and drying the first layer slurry and the second layer slurry after applying the first layer slurry and the second layer slurry to obtain a laminated structure in which a first layer and a second layer are laminated in this order on the current collector. The second layer slurry has a solid content ratio of more than 50% by mass and a composition ratio of the second binder of more than 2% by mass.

The present application provides a positive electrode sheet which may include a current collector and a positive film layer provided on at least one surface of the current collector. The positive film layer may include a lithium manganese oxide in which a trivalent manganese element and a tetravalent manganese element may coexist and a high-oxidizability additive, and the high-oxidizability additive being used to oxidize Mn.sup.2+ to Mn.sup.3+ and/or Mn.sup.4+.

An electrolyte solution for a lithium ion secondary battery, containing a compound (1) represented by the following formula (1): ##STR00001##
wherein R.sup.1 and R.sup.2 are each independently a C1-C4 alkyl group optionally containing an ether bond, and wherein chloride ion is present at a concentration of 1.0×10.sup.−6 to 1.0×10.sup.3 ppm. Also disclosed is an electrolyte solution for a lithium ion secondary battery, containing an imidazolium cation (1-1) represented by the following formula (1-1), a bis(oxalato)borate anion, and a hexafluorophosphate anion, the formula (1-1) being: ##STR00002##
wherein R.sup.1 and R.sup.2 are each independently a C1-C4 alkyl group optionally containing an ether bond, and wherein chloride ion is present at a concentration of 1.0×10.sup.−6 to 1.0×10.sup.3 ppm.

Provided is a non-aqueous electrolyte secondary battery that can be produced while mixing at an interface between a positive electrode active material layer and a heat resistant layer is restricted even if a positive electrode slurry and a heat resistant layer slurry are simultaneously applied. The non-aqueous electrolyte secondary battery disclosed here includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector, a positive electrode active material layer formed on the positive electrode current collector, and a heat resistant layer which is formed on the positive electrode current collector and is adjacent to the positive electrode active material layer. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material is porous particles in which primary particles are aggregated. The positive electrode active material has a dibutyl phthalate oil absorption of 26.5 mL/100 g or more and 45.0 mL/100 g or less. The heat resistant layer contains an inorganic filler. A ratio of a tap density of the positive electrode active material to a tap density of the inorganic filler is 1.32 or more and 2.44 or less.

Provided is a non-aqueous electrolyte secondary battery that can be produced while mixing at an interface between a positive electrode active material layer and a heat resistant layer is restricted even if a positive electrode slurry and a heat resistant layer slurry are simultaneously applied. The non-aqueous electrolyte secondary battery disclosed here includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector, a positive electrode active material layer formed on the positive electrode current collector, and a heat resistant layer which is formed on the positive electrode current collector and is adjacent to the positive electrode active material layer. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material is porous particles in which primary particles are aggregated. The positive electrode active material has a dibutyl phthalate oil absorption of 26.5 mL/100 g or more and 45.0 mL/100 g or less. The heat resistant layer contains an inorganic filler. A ratio of a tap density of the positive electrode active material to a tap density of the inorganic filler is 1.32 or more and 2.44 or less.

An electrochemical device including an electrolyte. The electrolyte includes a non-fluorinated cyclic carbonate and an ether multi-nitrile compound. The non-fluorinated cyclic carbonate includes ethylene carbonate. Based on a mass of the electrolyte, a content of the ethylene carbonate is X %, and a content of the ether multi-nitrile compound is A %. The electrochemical device further includes a positive electrode. The positive electrode includes a positive electrode active material layer and a positive current collector. The positive electrode active material layer includes a positive electrode active material. The positive electrode active material includes an element M. The element M includes at least one of Al, Mg, Ti, Zr, or W. Based on a mass of the positive electrode active material, a content of the element M is C ppm, 1000≤C≤22000, X+A≤15, and 133≤C/A≤22000.

An electrochemical device including an electrolyte. The electrolyte includes a non-fluorinated cyclic carbonate and an ether multi-nitrile compound. The non-fluorinated cyclic carbonate includes ethylene carbonate. Based on a mass of the electrolyte, a content of the ethylene carbonate is X %, and a content of the ether multi-nitrile compound is A %. The electrochemical device further includes a positive electrode. The positive electrode includes a positive electrode active material layer and a positive current collector. The positive electrode active material layer includes a positive electrode active material. The positive electrode active material includes an element M. The element M includes at least one of Al, Mg, Ti, Zr, or W. Based on a mass of the positive electrode active material, a content of the element M is C ppm, 1000≤C≤22000, X+A≤15, and 133≤C/A≤22000.