锂离子电池(LIBs)在低温条件下会出现阻抗增大、嵌入/脱嵌锂不平衡、循环效率降低、容量衰减等现象,导致充电比放电更加困难,严重影响了LIBs的低温性能,其中对LIBs低温性能影响最大的是电解液。电解液在低温下黏度变大,与电极材料和隔...锂离子电池(LIBs)在低温条件下会出现阻抗增大、嵌入/脱嵌锂不平衡、循环效率降低、容量衰减等现象,导致充电比放电更加困难,严重影响了LIBs的低温性能,其中对LIBs低温性能影响最大的是电解液。电解液在低温下黏度变大,与电极材料和隔膜之间的相容性变差,导致离子电导率降低,电荷转移电阻增大,最终导致电池性能下降。本文基于web of science核心合集数据库对LIBs用低温电解液有关文献进行可视化图谱分析。利用CiteSpace分析后可知,低温电解液的研究经历可分为三个阶段:起步阶段、平稳阶段和快速发展阶段。研究力量主要集中在中国、美国、日本、德国等国家,中国逐渐成为科研的核心力量。各个国家、科研机构之间的合作越来越密切,越来越多的科研人员参与到研究中来。目前开发新型低温电解液主要有两条路线:①设计低黏度、高离子电导率的多元电解液,辅以功能添加剂来提升低温性能;②通过研究SEI膜的界面结构和性质,设计高扩散系数的电极材料增大Li+在低温下的迁移率以此提升低温性能。除此以外,未来固体电解质的突破有可能彻底解决LIBs低温性能不良的问题。与此同时,结合计算材料科学可以加速研发过程,有助于产学研的深度融合。展开更多
To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA(1:1:2, mass ratio), EC/EMC/EP(1:1:2, mass ratio) and EC/EMC/EB(1:1:2,...To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA(1:1:2, mass ratio), EC/EMC/EP(1:1:2, mass ratio) and EC/EMC/EB(1:1:2, mass ratio), were prepared to substitute for industrial electrolyte(EC/EMC/DMC). Then, 18650-type Li Mn2O4-graphite cells(nominal capacity of 1150 mA ·h) were assembled and studied. Results show that the cells containing three types of electrolyte are able to undertake 5C discharging current with above 93% capacity retention at-20 °C. Electrochemical impedance spectra show that the discharge capacity fading of Li-ion cells at low temperature is mainly ascribed to the charge transfer resistance increasing with temperature decreasing. In comparison, the cells containing electrolyte of 1.0 mol/L LiPF6 in EC/EMC/EA(1:1:2, mass ratio) have the highest capacity retention of 90% at-40 °C and 44.41% at-60 °C, due to its lowest charge-transfer resistance.展开更多
文摘锂离子电池(LIBs)在低温条件下会出现阻抗增大、嵌入/脱嵌锂不平衡、循环效率降低、容量衰减等现象,导致充电比放电更加困难,严重影响了LIBs的低温性能,其中对LIBs低温性能影响最大的是电解液。电解液在低温下黏度变大,与电极材料和隔膜之间的相容性变差,导致离子电导率降低,电荷转移电阻增大,最终导致电池性能下降。本文基于web of science核心合集数据库对LIBs用低温电解液有关文献进行可视化图谱分析。利用CiteSpace分析后可知,低温电解液的研究经历可分为三个阶段:起步阶段、平稳阶段和快速发展阶段。研究力量主要集中在中国、美国、日本、德国等国家,中国逐渐成为科研的核心力量。各个国家、科研机构之间的合作越来越密切,越来越多的科研人员参与到研究中来。目前开发新型低温电解液主要有两条路线:①设计低黏度、高离子电导率的多元电解液,辅以功能添加剂来提升低温性能;②通过研究SEI膜的界面结构和性质,设计高扩散系数的电极材料增大Li+在低温下的迁移率以此提升低温性能。除此以外,未来固体电解质的突破有可能彻底解决LIBs低温性能不良的问题。与此同时,结合计算材料科学可以加速研发过程,有助于产学研的深度融合。
基金Project(2007BAE12B01)supported by the National Key Technology Research and Development Program of ChinaProject(20803095)supported by the National Natural Science Foundation of China
文摘To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA(1:1:2, mass ratio), EC/EMC/EP(1:1:2, mass ratio) and EC/EMC/EB(1:1:2, mass ratio), were prepared to substitute for industrial electrolyte(EC/EMC/DMC). Then, 18650-type Li Mn2O4-graphite cells(nominal capacity of 1150 mA ·h) were assembled and studied. Results show that the cells containing three types of electrolyte are able to undertake 5C discharging current with above 93% capacity retention at-20 °C. Electrochemical impedance spectra show that the discharge capacity fading of Li-ion cells at low temperature is mainly ascribed to the charge transfer resistance increasing with temperature decreasing. In comparison, the cells containing electrolyte of 1.0 mol/L LiPF6 in EC/EMC/EA(1:1:2, mass ratio) have the highest capacity retention of 90% at-40 °C and 44.41% at-60 °C, due to its lowest charge-transfer resistance.