Charge–discharge characteristics of all-solid-state thin-filmed lithium-ion batteries using amorphous Nb2O5 negative electrodes

All-solid-state thin-filmed lithium-ion rechargeable batteries composed of amorphous Nb2O5 negative electrode with the thickness of 50–300 nm and amorphous Li2Mn2O4 positive electrode with a constant thickness of 200 nm, and amorphous Li3PO4−xNx electrolyte (100 nm thickness), have been fabricated on glass substrates with a 50 mm × 50 mm size by a sputtering method, and their electrochemical characteristics were investigated. The charge–discharge capacity based on the volume of positive electrode increased with increasing thickness of negative electrode, reaching about 600 mAh cm−3 for the battery with the negative electrode thickness of 200 nm. But the capacity based on the volume of both the positive and negative electrodes was the maximum value of about 310 mAh cm−3 for the battery with the negative electrode thickness of 100 nm. The shape of charge–discharge curve consisted of a two-step for the batteries with the negative electrode thickness more than 200 nm, but that with the thickness of 100 nm was a smooth S-shape curve during 500 cycles.