Tape‐casting electrode architecture permits low‐temperature manufacturing of all‐solid‐state thin‐film microbatteries

Along with the constantly evolving functional microsystems toward more diversification, the more rigorous design deliberation of pursuing higher mass‐loading of electrode materials and low‐temperature fabrication compatibility have imposed unprecedented demand on integrable all‐solid‐state thin‐film microbatteries. While the classic thin‐film intercalation cathode prepared by vacuum‐based techniques inevitably encountered a post‐annealing process, tape‐casting technologies hold great merits both in terms of high‐mass loading and low‐temperature processing. In this work, a novel microbattery configuration is developed by the combination of traditional tape‐casting thick electrodes and sputtered inorganic thin‐film solid electrolytes (~3 μm lithium phosphorus oxynitride). Enabled by physically pressed or vapor‐deposited Li as an anode, solid‐state batteries with tape‐casted LiFePO4 electrodes exhibit outstanding cyclability and stability. To meet integration requirements, LiFePO4/LiPON/Si microbatteries were successfully fabricated at low temperatures and found to achieve a wide operating temperature range. This novel configuration has good prospects in promoting the thin‐film microbattery enabling a paradigm shift and satisfying diversified requirements. Low‐temperature tape‐casting processing settles the high‐temperature treatment encountered by intercalation thin‐film cathodes in all‐solid‐state thin‐film microbatteries. A casted‐LiFePO4/LiPON/Li prototype cell is systematically evaluated and demonstrates the possibility of stabilized ion transport at the LiFePO4/LiPON interface. Full cells created with sputtered silicon anodes exhibit promising merits of low‐temperature fabrication, integrability, and elevated temperature tolerance up to 150°C.