A Lithium‐Silicon Microbattery with Anode and Housing Directly Made from Semiconductor Grade Monocrystalline Si

Abstract Miniaturized and rechargeable energy storage systems, which easily power smart and (in vivo) sensors or the wirelessly networked transmitting devices of the so‐called internet of things, are expected to open unprecedented ways for how information can be shared autonomously. On the macroscale, such battery‐powered devices have already revolutionized our daily life by the use of mobile phones and portable computers. The eagerly‐awaited advent of sufficiently powerful and long‐living microbatteries will definitely make our lives more comfortable, especially in sectors such as medicine, security, autonomous driving or artificial intelligence in conjunction with fields where information need to be quickly shared, also including pandemic‐like situations. Here, a fully matured lithium‐ion microbattery with millimeter‐sized dimensions that can be manufactured by mass production methods well‐established in semiconductor industry is presented. The battery can directly be machined from wafer‐grade monocrystalline silicon which acts as both the electrochemically active anodic part and, at the same time, as the electrically insulating housing material of the accumulator. The high current output power (200 mW cm⁻²; 30 mA peak current) and the solid charge‐discharge stability of at least 100 cycles (10 mAh cm⁻²), combined with a high Coulombic efficiency near 100%, make the device ideally suited to be implemented in a large range of intelligent, self‐powered electric devices.