锂离子电池双壳硅基复合负极材料制备及性能

Preparation and properties of bishell silicon matrix composite anode materials for lithium ion batteries

针对硅基负极材料在体积膨胀、HF腐蚀、SEI膜不稳定、电导率低等问题,降低了其材料的稳定性和实用性,基于此,提出了一种基于硅纳米核颗粒与碳化层构筑核壳型硅碳为内核即内壳,通过化学或机械方法,在其内壳表面包覆纳米级纤维状多孔氧化锡层、HF隔绝层和最外层人造SEI膜功能Li+导体层为外壳,制备得到一种多层包覆硅基核壳结构的双壳结构锂离子电池负极材料。实验结果表明,该双壳硅基负极材料首次效率高达98.8%,300次循环后容量保持率仍有96.4%。实验结果验证了该双壳结构不但可以弥补硅基内核与包覆材料各自的缺陷,而且通过协同作用大幅提升了硅基负极材料在首次效率、容量保持率、高能量密度、高稳定性和循环寿命等方面的性能。

Due to the volume expansion,HF corrosion,instability of SEI film and low electrical conductivity of siliconbased anode materials,the stability and practicability of the materials is reduced.A core-shell type silicon-based carbon as the core or inner shell based on silicon nano core particles and carbonization layer was proposed.The inner shell was coated with nanometer fibrous porous tin oxide layer,HF isolation layer and the outermost artificial SEI film functional Li+conductor layer.A kind of double shell structure anode material with multi-layer silicon core-shell structure was prepared.The experimental results show that the first efficiency of the double shell silicon-based anode material is up to 98.8%.After 300 cycles,the capacity retention rate can still reach 96.4%.The double shell structure can not only make up for the defects of the silicon-based core and the coating material,but also greatly improve the performance of the silicon-based anode material in the aspects of initial efficiency,capacity retention rate,high energy density,high stability and cycle life through synergistic effect.