Single‐Crystal Silicon Membranes with High Lithium Conductivity and Application in Lithium‐Air Batteries
Single‐Crystal Silicon Membranes with High Lithium Conductivity and Application in Lithium‐Air Batteries
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DOI：
10.1002/adma.201102449
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发表时间：
2011-11
影响因子：
29.4
通讯作者：
T. Truong;Y. Qin;Yang Ren;Zonghai Chen;M. Chan;J. Greeley;K. Amine;Yugang Sun
中科院分区：
文献类型：
--
作者：
T. Truong;Y. Qin;Yang Ren;Zonghai Chen;M. Chan;J. Greeley;K. Amine;Yugang Sun
硅已经成为锂离子二次电池中令人感兴趣的阳极材料，因为其理论上高的锂化重量和体积容量（即，4200和1750 mA h cm − 3）。[ 1-6 ]为了接近理论极限，锂在硅中的电导率应该很高，因为锂进出硅的扩散速率决定了放电/充电速度并影响电池性能。[ 7-9 ]例如，已经投入了巨大的努力来利用纳米结构的硅来改善锂离子电池的电化学性能，因为预期减小硅的横向尺寸将增加锂的扩散速率并减少用于在电解质和阳极之间有效交换锂离子的扩散时间。[ 4，10-20 ]此外，硅纳米结构的大的表面积与体积比可以促进在锂化/脱锂期间适应它们的大体积膨胀/收缩。[ 2，4，12-14 ]然而，减小硅结构的尺寸并不总是有助于需要锂离子选择性扩散穿过连续膜的应用，例如锂离子选择性电极（Li-ISE）。[ 21-24 ]这种应用促使我们研究锂在扩展的大面积硅膜中的扩散行为，特别是具有连续晶格的单晶硅膜。在这里，我们报告的精确测量锂在单晶硅膜的电导率和连续电流下的膜的结构变化的原位监测。结果表明，这种单晶硅膜具有优异的锂电导率，高达1010 - 6 S cm-1，即使在1 mA cm-2的电流密度下，其单晶度也保持不变。高导电性和结构稳定性使得单晶
Silicon has become an intriguing anode material in lithium ion secondary batteries because of its theoretical high gravimetric and volumetric capacity for lithiation (i.e., 4200 and 1750 mA h cm − 3 , respectively). [ 1–6 ] To approach the theoretical limits, the conductivity of lithium in silicon should be high because the diffusion rate of lithium in and out of silicon determines the discharge/charge speed and infl uences the battery performance. [ 7–9 ] For example, enormous efforts have been devoted to utilizing nanostructured silicon to improve the electrochemical performance of lithium-ion batteries since decreasing the lateral dimensions of silicon is expected to increase the diffusion rate of lithium and reduce the diffusion time for effi ciently exchanging lithium ions between electrolytes and anodes. [ 4 , 10–20 ] Moreover, the large surface-to-volume ratios of silicon nanostructures can facilitate accommodation of their large volume expansion/contraction during lithiation/ delithiation. [ 2 , 4 , 12–14 ] However, reducing the size of silicon structures is not always helpful for applications that require selective diffusion of lithium ions across a continuous membrane, such as for a lithium ion selective electrode (Li-ISE). [ 21–24 ] This kind of application motivated us to study the diffusion behavior of lithium in extended, large-area silicon membranes, in particular, single-crystalline silicon membranes with continuous lattices. Herein we report the precise measurement of lithium conductivity in single-crystalline silicon membranes and in-situ monitoring of the structural variation of the membranes under continuous current fl ows. The results reveal that the singlecrystalline silicon membranes exhibit exceptional lithium conductivity as high as ∼ 10 − 6 S cm − 1 and their single crystallinity remains even with a current density of 1 mA cm − 2 . The high conductivity and structural stability makes the single-crystalline