Flexible all-solid proton batteries using inorganic nanosheets

Flexible, thin-film type batteries have a variety of applications, such as power sources of miniaturized & wearable electronic devices. High safety is required for those devices, as well as high energy & power densities.... [ view full abstract ]

Flexible, thin-film type batteries have a variety of applications, such as power sources of miniaturized & wearable electronic devices. High safety is required for those devices, as well as high energy & power densities. All-solid proton batteries meet these demands, but it is difficult to make them flexible by using conventional ceramic processes. “Nanosheets” are plate-like particles with thickness of only a few nanometers, and are prepared by delamination of layer-structured compounds. We found that thin films prepared by restacking of nanosheets have excellent bending durability. Namely, their conductivities are kept almost unchanged under bending deformation. Thin-film batteries with total thickness of several micrometers were prepared with the restacked nanosheet-derived thin films; H_x(Ni_1/2Co_1/4Mn_1/4)O₂ (NCM) and RuO₂ for cathode and anode, respectively, and layered double hydroxide [Mg_0.75Al_0.25(OH)₂](CHeCOO^-)_0.25]･mH₂O (LDH) for a solid electrolyte. These batteries showed reversible energy storage properties, and their capacities were maintained almost unchanged even under bent state with a bending radius of 3 mm. In the talk, mechanisms of the bending durability and effects of electrode configuration are also described.