Novel Three‐Dimensional Mesoporous Silicon for High Power Lithium‐Ion Battery Anode Material

Various lithium insertion metals and alloys have been proposed as alternative anode materials. [ 5 ] In particular, silicon has received much attention on account of its highest theoretical capacity for lithium storage (4200 mAh g − 1 for Li 4.4 Si) and the moderate electrochemical potential versus Li/Li + . [ 6 , 7 ] However, the process of lithium insertion/extraction is accompanied by huge volume changes ( > 300%) which lead to the damage of mechanical integrity of the electrode and pulverization of the particles. As a result, the electrode suffers a rapid capacity fade upon cycling. [ 8 ] Many approaches have been pursued to accommodate the volume changes of silicon, such as preparation of the Si-C composites to improve electric conductivity and prevent the breakdown of particles, [ 9 , 10 ] reduction of the active phases to the nanometer regime (e.g. nanospheres, [ 11 , 12 ] nanowires [ 13 ] and nanotubes [ 14 ] ) and fabrication of Si-based alloy or composite heterostructures. [ 15 , 16 ] All of the above attempts have brought signifi cant improvements of the cycle life and/or rate properties. In recent years, more attention has been paid to porous Si-based anode materials to avoid the common problems of ultra-fi ne powders (especially those with the particle size less than 100 nm), such as strong aggregation tendency, diffi cult transport and application. The basic strategy is that porous structure can provide suffi cient inner free space to absorb the large volume expansions and thereby enhance the cycling stability. Moreover, the open structure of the porous particles is favorable for fast transport of Li + and gives rise to high rate performance. Cho et al. synthesized a three-Dimensional (3D) porous Si using SiO 2 particles as templates which showed a reversible capacity of 2800 mAh g − 1 with excellent cycling performance. [ 17 ] Its capacity retention was 72% up to 100 cycles at a rate of 3C. However, the complicated and high-cost synthesis process may hinder its large-scale production. Yu et al. reported a 3D macroporous Si anode material via a magnesiothermic