Lithium ion secondary battery including a composition containing lithium and boron
Provided is an all-solid lithium ion secondary battery including a sintered body including a solid electrolyte layer and a positive electrode layer and a negative electrode layer which are stacked alternately with the solid electrolyte layer interposed therebetween, wherein: the positive electrode layer, the negative electrode layer, and the solid electrolyte layer include a compound containing lithium and boron; and a content of lithium and boron contained in the compound to a total of a positive electrode active material included in the positive electrode layer, a negative electrode active material included in the negative electrode layer, and a solid electrolyte included in the solid electrolyte layer is respectively 4.38 mol % to 13.34 mol % in terms of Li 2 CO 3 and 0.37 mol % to 1.11 mol % in terms of H 3 BO 3 .
1. A lithium ion secondary battery comprising a sintered body including a solid electrolyte layer, and a positive electrode layer and a negative electrode layer which are stacked alternately with the solid electrolyte layer interposed therebetween, the lithium ion secondary battery being an all-solid type wherein:
the positive electrode layer, the negative electrode layer, and the solid electrolyte layer include a composition containing a lithium compound and a boron compound, and
a content of lithium and boron contained in the composition to a total of a positive electrode active material included in the positive electrode layer, a negative electrode active material included in the negative electrode layer, and a solid electrolyte included in the solid electrolyte layer is respectively in a range of 4.38 mol % to 13.34 mol % in terms of Li 2 CO 3 and in a range of 0.37 mol % to 1.11 mol % in terms of H 3 BO 3 ,
wherein the composition exists at grain boundaries of the positive electrode active material, the negative electrode active material, and the solid electrolyte.
2. The lithium ion secondary battery according to claim 1 , wherein the composition is amorphous.
3. The lithium ion secondary battery according to claim 1 , wherein the solid electrolyte is at least one selected from a group consisting of Li 3+x1 Si x1 P 1−x1 O 4 (0.4≤x1≤0.6), Li 1+x2 Al x2 Ti 2−x2 (PO 4 ) 3 (0≤x2≤0.6), germanium lithium phosphate (LiGe 2 (PO 4 ) 3 ), Li 2 O—V 2 O 5 —SiO 2 , and Li 2 O—P 2 O 5 —B 2 O 3 .
4. The lithium ion secondary battery according to claim 1 , wherein the positive electrode active material and the negative electrode active material are at least one selected from a group consisting of lithium manganese composite oxide Li 2 Mn x3 Ma 1−x3 O 3 (0.8≤x3≤1, Ma=Co, Ni), lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganese spinel (LiMn 2 O 4 ), composite metal oxides represented by general formula: LiNi x4 Co y4 Mn z4 O 2 (x4+y4+z4=1, 0≤x4≤1, 0≤y4≤1, 0≤z4≤1), a lithium vanadium compound (LiV 2 O 5 ), olivine LiMbPO 4 (wherein Mb represents one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, and Zr), vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 or LiVOPO 4 ), Li-excess solid solution positive electrode Li 2 MnO 3 -LiMcO 2 (Mc=Mn, Co, Ni), lithium titanate (Li 4 Ti 5 O 12 ), and composite metal oxides represented by Li a Ni x5 Co y5 Al z5 O 2 (0.9<a<1.3, 0.9<x5+y5+z5<1.1).
5. The lithium ion secondary battery according to claim 1 , wherein:
the solid electrolyte is lithium phosphosilicate (Li 3+x1 Si x1 P 1−x1 O 4 (0.4≤x1≤0.6)); and
the positive electrode active material and the negative electrode active material are Li 2 Mn x3 M 1−x3 O 3 (0.8≤x3≤1, M=Co, Ni).