From Electrode Architecture to Microsystem Integration: Co-Design Principles for High-Performance Microbatteries

The rapid development of artificial intelligence, microelectromechanical systems, and wearable electronics, together with the diverse energy demands from the Internet of Things (IoT), drives the miniaturization of microelectronic systems. This has created an urgent need for compact, safe, and integrable energy storage technologies. Microbatteries are promising power sources for such microsystems, but they cannot be obtained by simply downsizing conventional lithium-ion batteries. At the microscale, size constraints and low active material loading, coupled with intertwined electrochemical transport, interfacial processes, fabrication, and system integration, lead to fundamental trade-offs among energy storage, power, reliability, and manufacturability. This review addresses microbattery development from the design-oriented and system-level perspectives. The root causes of the energy storage gap arising from microscale geometric and electrochemical scaling are firstly analyzed. Electrode materials, electrolytes, interface engineering, fabrication, packaging, and microsystem integration are considered in relation to these structural constraints. Particular attention is given to the translation of electrode-level performance into packaged-device performance. Improvements at the electrode level do not necessarily lead to corresponding gains at the device level, making consistent definitions of footprint, device volume, integration level, and operating duty cycle essential for meaningful comparisons. Practical microbattery development therefore requires the co-design of architecture, materials, fabrication, packaging, and load requirements.