Self-Supported 3D Array Electrodes for Sodium Microbatteries

The ever-increasing demand for autonomous microelectronic devices necessitates on-chip miniature energy storage systems such as microbatteries. Conventional microbatteries adopt planar thin-film electrodes that display limited areal energy and power due to their undesired coupling. To achieve high energy and power simultaneously, employment of 3D array electrodes has proven indispensable. Adoption of 3D electrodes has become a fashionable trend in lithium microbatteries during the last decade. This trend also occurs in sodium batteries, which are an important alternative to the current lithium system owing to the potentially high power and wide availability of sodium. In this perspective, state-of-the-art progress in design and application of 3D arrays for sodium microbatteries are summarized. Specifically, emphasis is placed on material strategies to efficiently address the intrinsic limitations of pristine arrays such as transportation, activity, and stability. Future challenges and prospects in this field are also discussed, and the importance of integrating novel concepts into 3D electrode fabrication, characterization, and modeling to meet practical requirements is highlighted.