Positive electrode mixture, positive electrode and secondary battery

A positive electrode mixture comprising:

• a polyvinylidene fluoride (A);
• a positive electrode active material (C) represented by the general formula (C):
• LiyNi1-XMxO2,
• wherein x is 0.01≤x≤0.7, y is 0.9≤y≤2.0, and M represents a metal atom excluding Li and Ni;
• and
• an additive (D),
• wherein the polyvinylidene fluoride (A) is a combination of:
• (A2) a polymer containing vinylidene fluoride unit and a fluorinated monomer unit excluding vinylidene fluoride unit and tetrafluoroethylene unit;
• and
• at least one selected from the group consisting of (A3) a polymer containing vinylidene fluoride unit and a polar group-containing monomer unit, and (A4) a polymer containing vinylidene fluoride unit, a fluorinated monomer unit excluding vinylidene fluoride unit and tetrafluoroethylene unit, and a polar group-containing monomer unit, and
• wherein the additive (D) is at least one selected from the group consisting of:
• a diketone compound (1) represented by the general formula (1);
• an amine compound (2) represented by the general formula (2);
• an organophosphorus compound (3);
• a sulfur-containing compound (4);
• an aminocarbonate compound (5) represented by the general formula (5);
• a carboxylic acid (6), excluding the aminocarbonate compound (5);
• and
• an oxalato complex compound (7):
• the general formula (1):
• wherein R11 and R13 independently represent a linear or branched non-fluorinated alkyl group having 1 to 6 carbon atoms or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms, R12 represents a linear or branched alkylene group having 1 to 4 carbon atoms;
• the general formula (2):
• wherein R21 represents a single bond or a divalent organic group, X21 to X24 independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group optionally bonded to a nitrogen atom via a sulfonyl group, X21 and X23 are optionally bonded to each other to form a ring, and X22 and X24 are optionally bonded to each other to form a ring;
• and
• the general formula (5):
• wherein R51 represents an organic group, R52 represents a single bond or an alkylene group, X52 represents —OH or —COOZ52, where Z52 is a hydrogen atom or an alkali metal, R53 represents a single bond or an alkylene group, X53 is —H, —OH or —COOZ53, where Z53 is a hydrogen atom or an alkali metal, and b represents 1 or 2.