Integratable and Wide‐Temperature All‐Solid‐State Thin Film Lithium‐Ion Microbatteries Based on LixMnO₂/Nb₂O5‐x Configuration

All‐solid‐state thin film lithium‐ion microbatteries (TFBs) are regarded as the ideal on‐board power sources for microelectronic devices. However, the indispensable high preparation temperature (≥500 °C) required for commonly used cathodes, coupled with the Li anode's low melting point and high chemical reactivity, restricts TFBs’ on‐chip integration and high‐temperature operational capabilities. In this work, a Li x MnO 2 /LiPON/Nb 2 O 5‐x configuration (LMN‐TFB), featuring a low preparation temperature (180 °C) and exceptional chemical and thermal stability, is proposed to simultaneously enable a wide operational temperature range and on‐chip multilayer integration. The LMN‐TFB exhibits a reversible capacity of 26.5 µAh cm −2 and a long cycle life (83.5% capacity retention after 1500 cycles) at room temperature, as well as adequate working ability in a wide temperature range between ‐20 and 210 °C. Moreover, the integration of multilayer stacked LMN‐TFBs on a chip allows for increased capacity (37.5 µAh cm −2 ) or higher working voltage (6.5 V) than the individual LMN‐TFB, resulting in increased areal energy densities within the limited footprint area without significantly increasing the volume or weight. This work presents a promising approach for constructing integratable and wide‐temperature TFBs, offering significant potential for on‐board microelectronic devices.