Battery

1. A battery comprising:

a positive electrode including a positive electrode active material;

a negative electrode; and

an electrolytic solution including a lithium hexafluorophosphate and an additive, wherein

the positive electrode active material includes a compound having a crystal structure belonging to a space group FM- 3 M and represented by Compositional Formula (1):

Li x Me y O α F β   (1)

where Me is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr; and

subscripts x, y, α, and β satisfy the following requirements:

1.7≤x<2,

0.8≤y≤1.3,

1≤α≤2.5,

0.5≤β≤2, and

x+y=α+β=3, and

the additive is at least one selected from the group consisting of difluorophosphates, tetrafluoroborates, bis(oxalate)borate salts, bis(trifluoromethanesulfonyl)imide salts, and bis(fluorosulfonyl)imide salts, and

wherein the electrolytic solution includes 0.05 mol/L or more and 0.5 mol/L or less of the additive.

2. The battery according to claim 1 , wherein

the electrolytic solution includes 0.05 mol/L or more and 0.2 mol/L or less of the additive.

3. The battery according to claim 1 , wherein

the electrolytic solution includes 0.5 mol/L or more and 2.0 mol/L or less of lithium hexafluorophosphate.

4. The battery according to claim 1 , wherein

the electrolytic solution includes a nonaqueous solvent, and

the nonaqueous solvent is at least one selected from the group consisting of carbonates, carboxylates, ethers, and nitriles.

5. The battery according to claim 4 , wherein

the electrolytic solution further includes fluoroethylene carbonate.

6. The battery according to claim 1 , wherein

Me includes at least one selected from the group consisting of Mn, Co, and Ni.

7. The battery according to claim 6 , wherein

Me is an element selected from the group consisting of Mn and Co or is a solid solution composed of Ni, Co, and Mn.

8. The battery according to claim 1 , wherein

the positive electrode active material includes 90 wt % or more of the compound.

9. The battery according to claim 1 , wherein

the compound satisfies:

1.79≤x<2;

0.82≤y≤1.21;

1.5≤α≤2.5; and

0.5≤β≤1.5.

10. The battery according to claim 9 , wherein

the compound satisfies:

x<2;

y=1;

1.5≤α≤2; and

1≤β≤1.5.