摘要
针对锂离子电池硅碳负极体积膨胀大、循环稳定性差、导电性不佳、能耗高等问题,本研究以纳米硅为活性物质、石墨为导电载体、沥青为碳前驱体、氯化钾为造孔模板剂,采用绿色节能的无溶剂法在较低温度下制备了多孔硅碳负极材料P-Si@G@C,并研究了其作为锂离子电池负极的性能,对比分析了不同结构硅碳负极的性能差异,阐明了构效关系。结果表明,用石墨载体锚定硅纳米颗粒(Si@G),有利于提高电极材料整体导电性,加快电子传输速率,并抑制纳米硅的体积膨胀;在Si@G表面包覆多孔碳壳层,大大减少了硅的体积膨胀,并加快了锂离子和电子的传输速率。相比Si@G和未造孔的Si@G@C硅碳负极材料,P-Si@G@C负极材料所构建的电池呈现出更优异的电性能。电池的首次库仑效率高达85.8%;在0.1、0.2、0.5、1.0、2.0、5.0 A·g^(–1)电流密度下,电池比容量分别高达1403.6、1291.7、1206.1、1093.6、868.4和609.5 mAh·g^(–1),且比容量恢复率达98.3%,倍率性能优异;在1.0 A·g^(–1)下循环200圈仍具有770.7 mAh·g^(–1)的比容量,表现出优异的长循环稳定性。
To solve the problems of large volume expansion,poor cycling stability,low electrical conductivity and high energy consumption of silicon-anode materials,a porous silicon-carbon anode material(P-Si@G@C)was prepared by a non-solvent low-temperature method with nano-silicon as active substance,graphite as conductive carrier,asphalt as carbon precursor,and potassium chloride as pore-forming agent.Structure and performance of P-Si@G@C anode were systematically studied by comparing with a series of silicon-carbon anodes.The results showed that insertion of silica nanoparticles in graphite matrix(Si@G)could improve the electrical conductivity of the whole material which is beneficial for electron transport,and the graphite matrix could alleviate the volume expansion of silica nanoparticles.Then the porous carbon shell coated on the surface of Si@G greatly reduced the volume expansion of nano-silicon,and improved the diffusion rate of lithium ion and electron transport rate.Compared with Si@G and unperforated Si@G@C anodes,the P-Si@G@C anode presented the best electrical performance with initial Coulombic efficiency of 85.8%.At the current density of 0.1,0.2,0.5,1.0,2.0,and 5.0 A·g^(–1),the specific capacities of P-Si@G@C anode were 1403.6,1291.7,1206.1,1093.6,868.4,and 609.5 mAh·g^(–1),respectively.Its recovery rate of specific capacity reached 98.3%,displaying excellent rate performance.The specific capacity still remained 770.7 mAh·g^(–1)after 200 cycles at 1.0 A·g^(–1),showing good long-cycle stability.
作者
易国刚
吴耀应
俎喜红
YI Guogang;WU Yaoying;ZU Xihong(Guangdong Nanhua Energy Conservation and Low Carbon Development Institution,Guangzhou 510635,China;School of Chemical Engineering and Light Industry,Guangdong University of Technology,Guangzhou 510006,China)
出处
《无机材料学报》
北大核心
2025年第12期1379-1386,共8页
Journal of Inorganic Materials
基金
国家自然科学基金(22378075)
广东省自然科学基金(2023A1515011851)。
关键词
锂离子电池
硅碳负极
双碳包覆
多孔壳层
储锂机制
lithium-ion battery
silicon-carbon anode
dual-carbon coating
porous shell
lithium storage mechanism
