BATTERY

A battery with excellent output characteristics and stability. The battery comprising a cathode, an anode and a separator disposed between the cathode and the anode, wherein the cathode comprises an aqueous electrolyte and a cathode active material; wherein the anode comprises an anode active material; wherein the separator comprises a first oxide electrolyte sintered body and a resin; wherein the first oxide electrolyte sintered body has grain boundaries between crystal particles of a garnet-type ion-conducting oxide represented by a general formula (A); wherein a number average particle diameter of the crystal particles is 3 μm or less; and wherein the first oxide electrolyte sintered body satisfies the following formula 1: R/(R+R)≤0.6 where Ris an intragranular resistance value that is an ion conductivity resistance inside the crystal particles, and Ris a grain boundary resistance value that is an ion conductivity resistance of the grain boundaries between the crystal particles.