Silicon is a promising anode material for lithium ion battery, because of its highest theoretical capacity (4200 mAh/g). However, intrinsic drawbacks of silicon, e.g. pulverization due to repeating volume change in cycling, and low lithium ion diffusivity in silicon, set hindrances for silicon to be used in high power-density battery. Here we find porous structured silicon a promising anode material for lithium ion battery. Theoretical study shows the pores can help to stabilize the structure by means of providing additional spaces to accommodate large volume change during cycling, and therefore release the stress and strain inside silicon. In addition, the large surface area that accessible to electrolyte helps to shorten the diffusion length for lithium ions, which enables fast charge/discharge. Experimentally, we have employed porous silicon nanowires as a prototype to show the advantages of using porous structured silicon as lithium-ion battery anode. By combining with alginate binder, the porous silicon nanowire shows capacity larger than 1000 mAh/g after 2000 cycles at current rate of 4 A/g. Beyond that, we have developed a scalable and cost-efficient method to produce nano and micron porous silicon particles, which shows decent battery performance.

Porous structured silicon for lithium-ion battery anode

245th National Meeting (2013)

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