%0 Journal Article %A Qiangfeng Xiao %A Meng Gu %A Hui Yang %A Bing Li %A Cunman Zhang %A Yang Liu %A Fang Liu %A Fang Dai %A Li Yang %A Zhongyi Liu %A Xingcheng Xiao %A Gao Liu %A Peng Zhao %A Sulin Zhang %A Chongmin Wang %A Yunfeng Lu %A Mei Cai %B Nature Communications %D 2015 %G eng %P 8844 %R 10.1038/ncomms9844 %T Inward lithium-ion breathing of hierarchically porous silicon anodes %V 6 %8 05/2015 %! Nat Comms %X

Silicon has been identified as a highly promising anode for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is large volume change during the lithiation/delithiation cycle that results in chemomechanical degradation and subsequent rapid capacity fading. Here we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. On charge/discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward Li breathing with negligible particle-level outward expansion. Our mechanics analysis revealed that such inward expansion is enabled by the much stiffer lithiated layer than the unlithiated porous layer. LIBs assembled with the hp-SiNSs exhibit high capacity, high power and long cycle life, which is superior to the current commercial Si-based anode materials. The low-cost synthesis approach provides a new avenue for the rational design of hierarchically porous structures with unique materials properties.