Due to high theoretical specific capacity(4200 mAh/g), silicon is considered as one of the most promising materials for lithium-ion battery negative electrodes. Nano-silicon negative materials can effectively avoid the pulverization of the particles during cycling and have shorter Li⁺ and electron transport paths. The electrochemical performance of the corresponding electrodes is significantly improved compared to that of the micro-sized silicon based electrodes. However, the specific surface area of nano-materials is too large while the tap density is low, that limits the application of nano-silicon negative materials in practical production. In recent years, the strategy of using nano-structured silicon materials as building units to construct nano/micro structured silicon-based negative materials has been widely studied. The development of nano/micro structured silicon-based materials for lithium-ion batteries is reviewed. The selection and structural design elements of nano-sized primary particles as well as micro-sized secondary particles are summarized. The physical and electrochemical properties of representative nano/micro structured silicon-based materials are also introduced. Moreover, an optimized design of the nano/micro structured silicon-based material structure and electrode structure is proposed. Finally, challenges and problems existing in nano/micro structured silicon-based negative materials are briefly analyzed and prospects of them as negative materials for lithium-ion batteries are discussed.
Contents
1 Introduction
2 Structure of primary particles in nano/micro structured silicon-based negative materials
2.1 Primary particles of nano-silicon
2.2 Void space in primary particles
3 Design elements of secondary particles in nano/micro structured silicon-based negative materials
3.1 Void space in secondary particles
3.2 Surface coating of secondary particles
3.3 Size optimization of secondary particles
4 Conclusion and outlook