Fundamental Understanding and Facing Challenges in Structural Design of Porous Si-Based Anodes for Lithium-Ion Batteries

As one of the most electrochemical energy storage devices, lithium-ion batteries (LIBs) remain the workhorse of the energy market due to their unparalleled advantages. Remarkably, Si-based materials play a pivotal role in LIBs anodes owing to ultrahigh theoretical capacity of Si and rich natural resources. However, bulk silicon materials are difficult to meet the current commercial demand because of their low conductivity, sluggish reaction kinetics, and huge volume expansion. The construction of porous structures has been acknowledged as an effective way to solve the above issues. Herein, the delicate design of porous Si-based anode materials including synthetic strategies, the engineering of surface morphology and micro/nano-structure, and the regulation of different compositions, as well as their applications in LIBs is systematically summarized. Particularly, the fine engineering of different pore parameters for Si-based materials is on focus. Importantly, the relationship between thick electrodes and tortuosity/porosity, and the structural effect between pores and battery performance are also discussed in depth. Finally, the applications of porous Si-based anodes in full-cells and their commercial achievements are briefly described. This review is expected to provide a basic understanding and deep insight into developing porous Si-based anodes for high-energy lithium storage.