将硅纳米颗粒限域在多壳层空心球:一种提升循环稳定性的有效策略

Encapsulating Si nanoparticles in multi-shell hollow spheres:An effective approach to boost the cyclability

单质硅是一种有潜力的高容量锂离子电池负极材料.然而,受限于充放电过程中巨大的体积膨胀,其循环性能并不理想.在这个工作中,我们设计了一种独特的三组分复合负极材料(Si/Cr_(2)O_(3)/C),其中Si纳米颗粒被限域在碳包覆的氧化铬多层空心球(MSHSs)中.得益于Cr_(2)O_(3)/C基体的体积变化缓冲能力与优异的结构稳定性,将Si纳米颗粒封装在MSHSs中可以有效地提高其电化学性能.合理的结构设计赋予了Si/Cr_(2)O_(3)/C三组分复合材料高的可逆容量(在100 mA g^(-1)的电流密度下,比容量为1351 mA h g^(-1))和稳定的循环性能(在500 mA g^(-1)的电流密度下,循环300次后比容量保持在716 mA h g^(-1)).这一工作提出了一种多壳层空心结构设计的新思路,以解决硅基负极材料循环性差的瓶颈.

Silicon is an appealing lithium-ion battery anode material;unfortunately,it is confronted with unsatisfactory cyclability owing to its large volume change.Herein,we design a unique ternary composite anode material(Si/Cr_(2)O_(3)/C),where the Si nanoparticles are confined in carbon-coated chromium oxide multi-shell hollow spheres(MSHSs).Encapsulating the Si nanoparticles in the MSHSs effectively boosts the cyclability owing to the available free space for volume change buffering and the ideal structural stability of the Cr_(2)O_(3)/C hybrid matrix.The rationally designed Si/Cr_(2)O_(3)/C ternary composite demonstrates not only high reversible capacity(1351 mA h g^(-1)at 100 mA g^(-1))but also stable cycling(716 mA h g^(-1)after 300 cycles at 500 mA g^(-1)).This contribution proposes a novel multi-shell hollow structure design to solve the poor cyclability problem of Si-based anode materials.