Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA.
Nano Lett. 2012 May 9;12(5):2318-23. doi: 10.1021/nl300206e. Epub 2012 Apr 11.
Porous silicon nanowires have been well studied for various applications; however, there are only very limited reports on porous silicon nanowires used for energy storage. Here, we report both experimental and theoretical studies of porous doped silicon nanowires synthesized by direct etching of boron-doped silicon wafers. When using alginate as a binder, porous silicon nanowires exhibited superior electrochemical performance and long cycle life as anode material in a lithium ion battery. Even after 250 cycles, the capacity remains stable above 2000, 1600, and 1100 mAh/g at current rates of 2, 4, and 18 A/g, respectively, demonstrating high structure stability due to the high porosity and electron conductivity of the porous silicon nanowires. A mathematic model coupling the lithium ion diffusion and the strain induced by lithium intercalation was employed to study the effect of porosity and pore size on the structure stability. Simulation shows silicon with high porosity and large pore size help to stabilize the structure during charge/discharge cycles.
多孔硅纳米线在各种应用中得到了广泛研究；然而，用于储能的多孔硅纳米线的报道却非常有限。在这里，我们报告了通过对掺硼硅片进行直接刻蚀合成的多孔掺杂硅纳米线的实验和理论研究。当使用海藻酸钠作为粘结剂时，多孔硅纳米线作为锂离子电池的阳极材料表现出优异的电化学性能和长循环寿命。即使在 250 次循环后，在电流速率分别为 2、4 和 18 A/g 时，容量仍稳定在 2000、1600 和 1100 mAh/g 以上，这是由于多孔硅纳米线的高孔隙率和电子导电性，显示出了高结构稳定性。我们采用了一种将锂离子扩散和锂嵌入引起的应变耦合在一起的数学模型，来研究孔隙率和孔径对结构稳定性的影响。模拟表明，高孔隙率和大孔径的硅有助于在充放电循环过程中稳定结构。
