▎ 摘　　要

NOVELTY - Battery comprises a positive electrode and a negative electrode, where the positive electrode includes a positive electrode active material and a conductive additive. The positive electrode active material includes composite oxide containing lithium and manganese. The composite oxide has a first region (131), and a second region. The second region is located at a more surface side than the first region. The first region and the second region are included lithium and oxide, where at least one of the first region and the second region includes manganese and an element represented by M. The element represented by M is one or more elements selected from nickel, gallium, iron, molybdenum, indium, niobium, neodymium, cobalt, samarium, magnesium, aluminum, titanium, copper, zinc, silicon, and phosphorus, where element atomic ratio of lithium, manganese, the element represented by M, and oxygen in the first region is represented by al:b1:c1:d1. USE - Battery. ADVANTAGE - The battery has a relatively high capacity per unit volume, small volume expansion, low cost, and a higher level of safety than lithium metal, has reduced conductive paths of the electrode and causes a reduction in capacity in some cases, and has increased the resistance. It has reduced the amount of electric charge leaking, and it can be suppressed reduction in capacity with the lapse of time. DETAILED DESCRIPTION - Battery comprises a positive electrode and a negative electrode, where the positive electrode includes a positive electrode active material and a conductive additive. The positive electrode active material includes composite oxide containing lithium and manganese. The composite oxide has a first region and a second region. The second region is located at a more surface side than the first region. The first region and the second region are included lithium and oxide, where at least one of the first region and the second region includes manganese and an element represented by M. The element represented by M is one or more elements selected from nickel, gallium, iron, molybdenum, indium, niobium, neodymium, cobalt, samarium, magnesium, aluminum, titanium, copper, zinc, silicon, and phosphorus, where element atomic ratio of lithium, manganese, the element represented by M, and oxygen in the first region is represented by al:b1:c1:d1, where an atomic ratio of lithium, manganese, the element represented by M, and oxygen in the second region is represented by a2:b2:c2:d2, d1/(b1+c1) is greater than or equal to 2.2, d2/(b2+c2) is less than 2.2. The conductive additive includes carbon fiber or graphene. The negative electrode includes a negative electrode active material, and the negative electrode active material includes a carbon-based material. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the battery. cRegion 132Region 133Region