Lithium ion rechargeable battery

Abstract

A high power lithium-ion secondary battery having an increased capacity and capable of maintaining high discharge voltage and repeating charging/discharging high current. A lithium-ion secondary battery having an electrode group formed by laminating or winding a negative electrode layer and a positive electrode layer so as to interpose a separator made of synthetic resin, the negative electrode layer containing a material capable of intercalating/deintercalating lithium-ion, and the positive electrode layer including a lithium-containing metallic oxide; and a non-aqueous electrolyte containing lithium salt, where the electrode group is immersed. The positive electrode material unit contains a fluorinated lithium-containing metallic oxide as a main material, and the separator possesses a hydrophilic group. Further, the positive electrode material preferably contains a main material including LiNiCoMnO, where 0.6≦x<1, 0<y≦0.2, 0<z≦0.2, and x+y+z=1.