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Miniature power sources have gained widespread attention and accelerated progress with portable, wearable, and integrated electronic technologies. Micro lithium-ion batteries (μLIBs) featured small size, lightweight, high capacity, and long cycle life, which also offer stability, safety, and compatibility with microfabrication, make them the ideal choice for energy storage. Researchers have engaged in the performance optimization and application expansion of μLIBs, especially in the on-chip μLIBs with compatible integration for microdevices and flexible μLIBs for wearable applications. This paper reviews the working principles, performance metrics, and design methodologies of μLIBs, highlighting the advantages of the architecture design. Typical materials and fabrication methods are introduced, and their effects on the device performance and system integration are analyzed. The developments of μLIBs are summarized from the perspective of 3D architecture design to the on-chip and wearable applications. At last, the challenges and the prospects that inspire further research and development of μLIBs are concluded.

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Although silicon is intensively pursued as the most promising anode material for lithium‐ion batteries (LIBs), the extensive utilization of silicon is still impeded by severe capacity fading and limited cycle life. A robust layer‐by‐layer architecture of the silicon‐based anode, which shields silicon nanoparticles (SiNPs) with shell‐like reduced graphene oxide (rGO) layers supported by the intertwined framework of carbon nanotubes (CNTs), is developed. Such structure guarantees high reversible capacity and cyclic stability by enclosing SiNPs in the stable shells, which supplies sufficient void space for the expansion of SiNPs and prevents electrolyte‐consuming capacity. In addition, the electrode kinetics in the plane direction are enhanced due to the intimate contact between SiNPs and highly conductive rGO layers, while the highly conductive framework of CNTs has a similar impact on that in the direction of the vertical plane. As a result, the nanocomposite anode demonstrates an improved cycling stability with 1438.31 mAh g−1 after 100 cycles and a superior rate performance of 1112.64 mAh g−1 at 5 C rate in a half‐cell electrochemical test.