Flash Lamp Annealing Enables Thin-Film Solid-State Batteries on Aluminum Foil

Abstract

Crystallization of cathode films in solid-state microbatteries requires thermal annealing at high temperatures, restricting the choice of substrate and current collector materials. Here, flash lamp annealing (FLA) is explored to crystallize LiCoO2 (LCO) cathodes on aluminum foils. Millisecond pulses of visible light induce rapid heating of the LCO films up to 900 °C, whereas the aluminum never exceeds the melting point. Microbatteries consisting of an FLA-processed LCO cathode, a LiPON electrolyte, and a Li metal anode are fabricated on flexible aluminum foil, with performance comparable to those on rigid silicon. This method can enable new microbattery designs at lower production costs.