According to one embodiment, provided is a secondary battery including a negative electrode containing a titanium-containing oxide, a positive electrode, a separator between the negative electrode and the positive electrode, a first aqueous electrolyte, a second aqueous electrolyte, and a third aqueous electrolyte. The first aqueous electrolyte is held in the negative electrode and contains 0.001% by mass to 0.5% by mass of zinc ions. The second aqueous electrolyte is held in the separator and contains 1% by mass to 5% by mass of a first compound that includes a hydrophobic portion and a hydrophilic portion. The third aqueous electrolyte is held in the positive electrode.

A method for producing an electrode material for a lithium-ion secondary battery. The method includes the following steps: (a) mixing components of a basic ingredient or active substance of electrode material and a conductive carbon material to obtain a conductive carbon material-composited material; (b) mixing the conductive carbon material-composited material and a surface layer-forming material; an (c) burning the mixture obtained at step (b) to obtain the electrode material. Also, a lithium-ion secondary battery including an electrode which comprises the material.

A method for producing an electrode material for a lithium-ion secondary battery. The method includes the following steps: (a) mixing components of a basic ingredient or active substance of electrode material and a conductive carbon material to obtain a conductive carbon material-composited material; (b) mixing the conductive carbon material-composited material and a surface layer-forming material; an (c) burning the mixture obtained at step (b) to obtain the electrode material. Also, a lithium-ion secondary battery including an electrode which comprises the material.

A CoVO.sub.x composite electrode and method of making is described. The composite electrode comprises a substrate with an average 0.5-5 μm thick layer of CoVO.sub.x having pores with average diameters of 2-200 nm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a cobalt complex, and a vanadium complex. The CoVO.sub.x composite electrode is capable of being used in an electrochemical cell for water oxidation.

A CoVO.sub.x composite electrode and method of making is described. The composite electrode comprises a substrate with an average 0.5-5 μm thick layer of CoVO.sub.x having pores with average diameters of 2-200 nm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a cobalt complex, and a vanadium complex. The CoVO.sub.x composite electrode is capable of being used in an electrochemical cell for water oxidation.

An all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The solid electrolyte layer separates the positive electrode layer from the negative electrode layer. The positive electrode layer includes a positive electrode active material, a conductive material, an oxide-based lithium ion conductor, and a sulfide-based solid electrolyte. A cross section of the positive electrode layer satisfies a relational expression (1): 3%≤S.sub.B/S.sub.A≤30%. In the relational expression (1), “S.sub.A” represents a partial area of the oxide-based lithium ion conductor that is in contact with the positive electrode active material, and “S.sub.B” represents a partial area of the oxide-based lithium ion conductor that is surrounded by the sulfide-based solid electrolyte.

The present disclosure discloses a W-containing high-nickel ternary cathode material, including both spherical secondary particles and single-crystal particles. There is basically no W inside the single-crystal particles, and the spherical secondary particles are doped with W. A preparation method of the W-containing high-nickel ternary cathode material includes: mixing a nickel salt, a cobalt salt, and a manganese salt according to a specified molar ratio, and adding an ammonia solution and a sodium hydroxide solution for co-precipitation to prepare a precursor A; mixing a nickel salt, a cobalt salt, a manganese salt, and a tungsten salt, and adding an ammonia solution and a sodium hydroxide solution for co-precipitation to prepare a W-containing precursor B; and mixing the precursor A, the precursor B, a lithium source, and a doping element M-containing compound, and subjecting a resulting mixture to high-temperature sintering in an oxygen atmosphere to obtain the high-nickel ternary cathode material including both spherical secondary particles and single-crystal particles. While increasing the capacity, the spherical secondary particles in the product of the present disclosure can ensure that a crystal structure will not undergo obvious phase transition when lithium ions are deintercalated during a cycling process, which helps to improve the cycling performance.

The present invention provides a binder for a secondary battery having excellent binding force. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001##

in formula (1). R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and

when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is 2 mol % or more and 20 mol % or less.

The present invention provides a binder for a secondary battery having excellent binding force. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001##

in formula (1). R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and

when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is 2 mol % or more and 20 mol % or less.

A material of formula Li.sub.aTi.sub.b(A.sub.xS.sub.3-x).sub.c wherein A is a metalloid element chosen from selenium, tellurium and mixtures thereof, and the stoichiometric coefficients a, b, c and x are such that 0<x<2.2; 0.4≤a≤4.5; 0.9≤b≤1.1; and 0.9≤c≤1.1.