超高倍率长寿命大孔-介孔-微孔负极材料的精细构筑、调控和性能

Developing ultrahigh-rate and long-life anode materials would be a significant breakthrough for high-power Li-ion batteries involving in electric vehicles and back-up for wind and solar energy. However, the rate capabilities are currently restricted to in the range of ~1-10 C with current density about 1-5 A g-1. This project focuses on hierarchically bottom-up construction of 3D interconnected macro-meso-microporous Murray nanomaterials of metal oxides built by core@microporous shell nanoparticles on graphene foam substrates, and includes the following aspects: Optimizing the porous micro-nanostructures according the generalized Murray’s law to improve the Li-ion transfer in pores; Tuning the particle-sizes to promote the ultra-short Li-ion diffusion in solid-phase; Coordinating the two facets to highly enhance the rate capabilities of anode materials; Controlling the microporous shell to prevent the agglomeration of core, and the morphology of micropores to facilitate the Li-ion diffusion for maintaining the stability of nanoparticles under higher current densities. This project guides the achievement of ultrahigh-rate and long-life anode materials of metal oxides with rate-capabilities higher than 50 A g-1, and long-life charge-discharge up to 3000 cycles under current density higher than 5 A g-1 in Li-ion batteries applications.

超高倍率长寿命负极材料对发展高比功率动力储能锂离子电池，解决能源危机具有重大意义。目前所报道负极材料的倍率性能普遍不高（1-10 C），最大充放电电流密度大多局限在1-5 A g-1左右。本项目拟在泡沫石墨烯基体上，针对高容量的金属氧化物负极材料，来构筑和调控以核-微孔壳结构为基本单元，自组装形成的大孔（>50 nm）-介孔（2-50 nm）-微孔（<2 nm）精细分级结构：依据广义默里定律来调控大孔-介孔-微孔分级结构的孔径比例，增强锂离子在电极孔道中的扩散，调控颗粒的尺寸来缩短固相扩散路径，增强锂离子在电极固相中的扩散，研究利用协同效应来大幅提高负极材料的倍率性能；调控核-微孔壳结构中的多微孔碳壳层，研究核-微孔壳结构对高电流下纳米结构稳定性的影响规律；指引获得最大充放电电流密度高于50 A g-1，3000次以上循环充放电的电流密度大于5 A g-1的高倍率长寿命的金属氧化物负极材料。

超高倍率长寿命负极材料对发展高比功率动力储能锂离子电池，解决能源危机具有重大意义。本项目围绕超高倍率长寿命大孔-介孔-微孔负极材料的精细构筑、调控和性能，通过研究三维微纳多孔电极材料中，多孔结构、颗粒尺寸、界面结构等，对电极材料充放电倍率性能和循环稳定性能的影响规律和协同作用机理，构筑优化的多孔分级电极结构。优化锂离子在电极孔道中的传输，以及在电极中的固相扩散，协同大幅提高负极材料的充放电倍率性能。在本项目资助下，成功获得了具有大孔-介孔-微孔三维多孔结构的3种电极材料：MoC/C复合负极，和WS2/石墨烯复合负极，以及SiOC多孔负极；利用三维多孔结构的协同效应，提升了电极的倍率性能和循环寿命，获得了50 A g-1的充分电倍率性能，以及5 A g-1的电流密度下长达3000 次以上的循环稳定性，达成了预期技术指标；资助期间，发表相关国际期刊论文9篇，达成了预期的3-5篇指标。培养2名博士后成功出站，硕士生共计5名。