摘要
硅负极是锂离子电池理想的候选材料.然而,其显著的体积膨胀会导致严重的材料断裂,失去电接触,从而限制了其实际应用.本研究提出了一种新的自上而下的多孔硅制备策略,并引入聚丙烯腈(PAN)作为掺氮炭涂层,旨在保持硅负极的内部空间,缓解硅负极在锂化和脱锂过程中向外膨胀的问题.随后,探讨了温度对PAN热转变行为和复合电极电化学行为的影响.在400℃下处理后,PAN涂层保留了 11.35％的高氮掺杂含量,这明确证实了 C-N和C-O键的存在,从而改善了离子电子传输特性.这种处理方法不仅保留了更完整的炭层结构,还引入了炭缺陷,即使在大电流下也能稳定循环.当以4 A g-1的电流循环时,优化后的负极在循环200次后仍具有857.6 mAh g-1的比容量,表明其在高容量储能应用方面的巨大潜力.
Abstract
Silicon anodes are promising for use in lithium-ion batteries.However,their practical application is severely limited by their large volume expansion leading to irreversible material fracture and electrical disconnects.This study proposes a new top-down strategy for preparing microsize porous silicon and introduces polyacrylonitrile(PAN)for a nitrogen-doped carbon coating,which is designed to maintain the internal pore volume and lower the expansion of the anode during lithiation and delithiation.We then ex-plore the effect of temperature on the evolution of the structure of PAN and the electrochemical behavior of the composite electrode.After treatment at 400 ℃,the PAN coating retains a high nitrogen content of 11.35 at％,confirming the presence of C—N and C—O bonds that improve the ionic-electronic transport properties.This treatment not only results in a more intact carbon layer structure,but also introduces carbon defects,and produces a material that has remarkable stable cycling even at high rates.When cycled at 4 A g,the anode had a specific capacity of 857.6 mAh g-1even after 200 cycles,demonstrating great potential for high-capacity en-ergy storage applications.
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