Insights into the Electrochemical Reduction Products and Processes in Silica Anodes for Next-Generation Lithium-Ion Batteries
Insights into the Electrochemical Reduction Products and Processes in Silica Anodes for Next-Generation Lithium-Ion Batteries
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DOI：
10.1002/aenm.202001826
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发表时间：
2020-09-03
影响因子：
27.8
通讯作者：
Patwardhan, Siddharth V.
中科院分区：
文献类型：
--
作者：
Entwistle, Jake E.;Booth, Samuel G.;Patwardhan, Siddharth V.
使用二氧化硅作为锂离子电池负极材料需要一个前处理步骤来诱导电化学活性。二氧化硅和锂之间的部分可逆的电化学还原反应被认为可以产生硅，硅随后可以与锂发生可逆反应，提供比石墨材料更高的稳定容量。到目前为止，电化学还原的途径和产物的性质尚不清楚，从而阻碍了二氧化硅基阳极的设计、优化和更广泛的吸收。这里揭示了电化学还原的途径，并首次将元素硅确定为还原产物。对还原过程中的电流响应和容量增加的分析得出的结论是，二氧化硅必须被还原才能引入可逆容量，最高容量为600mAHg(-1)是通过在高温下恒定负载放电获得的。通过全散射X射线对分布函数分析进行的表征表明，还原产物本质上是无定形的，这突出表明需要使用局部结构方法来揭示通常无法通过传统衍射获得的重要信息。这些见解有助于理解二氧化硅的电化学还原，并可以为前处理工艺的开发提供信息，使其能够整合到下一代锂离子电池中。
The use of silica as a lithium-ion battery anode material requires a pretreatment step to induce electrochemical activity. The partially reversible electrochemical reduction reaction between silica and lithium has been postulated to produce silicon, which can subsequently reversibly react with lithium, providing stable capacities higher than graphite materials. Up to now, the electrochemical reduction pathway and the nature of the products were unknown, thereby hampering the design, optimization, and wider uptake of silica-based anodes. Here, the electrochemical reduction pathway is uncovered and, for the first time, elemental silicon is identified as a reduction product. These insights, gleaned from analysis of the current response and capacity increase during reduction, conclusively demonstrated that silica must be reduced to introduce reversible capacity and the highest capacities of 600 mAh g(-1)are achieved by using a constant load discharge at elevated temperature. Characterization via total scattering X-ray pair distribution function analysis reveal the reduction products are amorphous in nature, highlighting the need for local structural methods to uncover vital information often inaccessible by traditional diffraction. These insights contribute toward understanding the electrochemical reduction of silica and can inform the development of pretreatment processes to enable their incorporation into next-generation lithium-ion batteries.