SECONDARY BATTERY, BATTERY PACK, ELECTRONIC DEVICE, ELECTRICALLY DRIVEN VEHICLE, STORAGE DEVICE, AND POWER SYSTEM

摘要

A secondary battery includes a positive electrode including a positive electrode active material layer having a positive electrode active material, a negative electrode including a negative electrode active material layer having a negative electrode active material, and an electrolyte. The positive electrode active material contains at least either a lithium iron phosphate compound having an olivine structure or lithium-manganese composite oxide having a spinel structure. The negative electrode active material contains titanium-containing inorganic oxide. In the secondary battery, electrode areas of the positive electrode and the negative electrode, and first charge capacities and irreversible capacities per unit area of the positive electrode and the negative electrode satisfy predetermined formulas.

主权项

1. A secondary battery comprising:
a positive electrode including a positive electrode active material layer having a positive electrode active material; a negative electrode including a negative electrode active material layer having a negative electrode active material; and an electrolyte, wherein the positive electrode active material contains at least either a lithium iron phosphate compound having an olivine structure and containing at least lithium, iron, and phosphorus, or lithium-manganese composite oxide having a spinel structure and containing at least lithium and manganese, the negative electrode active material contains titanium-containing inorganic oxide, and the secondary battery satisfies Formula (A) , Formula (B), and Formula (C) below:
1.005≦(Ac/Aa)  Formula (A)(in the formula, Ac: an electrode area (cm2) of the positive electrode and Aa: an electrode area (cm2) of the negative electrode);
(Ac/Aa)<(QA1/QC1)  Formula (B)(in the formula, QC1 (mAh/cm2): a first positive electrode charge capacity per unit area and QA1 (mAh/cm2): a first negative electrode charge capacity per unit area); and
0.90≦(QCL/QAL)≦1.10  Formula (C)(in the formula, QCL (mAh/cm2): an irreversible capacity per unit area of the positive electrode and QAL (mAh/cm2): an irreversible capacity per unit area of the negative electrode).