物理化学学报 >> 2017, Vol. 33 >> Issue (4): 780-786.doi: 10.3866/PKU.WHXB201612291

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预嵌锂用穿孔集流体对锂离子电容器电化学性能的影响

蒋江民,聂平,董升阳,吴宇婷,张校刚*()   

  • 收稿日期:2016-10-20 发布日期:2017-03-23
  • 通讯作者: 张校刚 E-mail:azhangxg@163.com
  • 基金资助:
    国家重点基础研究发展规划(973)(2014CB239701);国家自然科学基金(51372116);国家自然科学基金(51672128);江苏省自然科学基金(BK20151468);江苏省产学研前瞻性联合研究(BY-2015003-7);江苏省高校优势学科建设工程(PAPD)

Effect of Pre-Punched Current Collector for Lithiation on the Electrochemical Performance of Lithium-Ion Capacitor

Jiang-Min JIANG,Ping NIE,Sheng-Yang DONG,Yu-Ting WU,Xiao-Gang ZHANG*()   

  • Received:2016-10-20 Published:2017-03-23
  • Contact: Xiao-Gang ZHANG E-mail:azhangxg@163.com
  • Supported by:
    the National Key Basic Research Program of China (973)(2014CB239701);National Natural Science Foundation of China(51372116);National Natural Science Foundation of China(51672128);Natural Science Foundation of Jiangsu Province, China(BK20151468);Prospective Joint Research Project of Cooperative Innovation Fund of Jiangsu Province, China(BY-2015003-7);Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China(PAPD)

摘要:

将石墨涂覆于传统铜箔(CCC)与穿孔铜箔(PCC)集流体表面,通过内部短路的方式进行预嵌锂处理,再以商业化的活性炭及预锂化的石墨分别为正、负极材料组装成锂离子电容器(LIC)。以PCC为集流体的LIC在0.1和2.0 A·g-1的电流密度下,能量密度分别为118.2和51.7 Wh·kg-1,并且在0.5 A·g-1的电流密度下循环1000次后的能量密度保持率为90%;以CCC为集流体的LIC在0.1和2.0A·g-1的电流密度下的能量密度分别为125.5和43.3 Wh·kg-1,在同等电流密度下2.0-3.8 V之间循环1000次后的能量密度保持率仅为73.2%。进一步研究表明,石墨采用PCC在预嵌锂的过程中避免了金属锂沉积,生成了均一且稳定的固体电解质膜(SEI),有效防止充放电过程中SEI膨胀,活性物质与集流体间粘结力降低,活性物质脱落等现象发生。因此,LIC通过PCC完成预嵌锂后的自放电及内阻更小,具有更佳的倍率性能和循环性能。

关键词: 锂离子电容器, 穿孔铜箔, 预嵌锂, 固体电解质膜, 集流体

Abstract:

Lithium-ion capacitor (LIC) using commercial activated carbon as the cathode and graphite as the anode was assembled. The graphite anode was pre-lithiated by a fast, efficient internal short approach, which involved placing graphite in direct contact with lithium foil with electrolyte additive. The effect of pre-lithiation on the electrochemical performance of the LIC was investigated using a conventional Cu current collector (CCC) and pre-punched Cu current collector (PCC). The LICs containing a CCC and PCC were named CLIC and PLIC, respectively. Although the CCC had slightly higher pre-lithiation level and higher energy density in the CLIC, it suffered from a considerable decrease in performance at higher charge-discharge rates. Meanwhile, 90.0% of the initial capacity was maintained in the PLIC, whereas that of the CLIC was only 73.2% after 1000 cycles in the voltage range from 2.0 to 3.8 V. The CCC led to solid electrolyte interphase (SEI) film expansion and Li metal plating with direct contact between graphite and lithium metal. The deposited thick SEI layer could weaken the adhesion of active materials and the current collector. Moreover, the expansion of the SEI layer itself produced electrical resistance and electrical contact loss between the active materials and current collector. In contrast, a thin, stable SEI layer formed on the surface of graphite after pre-lithiated using the PCC. Therefore, the PLIC showed better rate and cycle performance with the smaller self-discharge, voltage drop, and resistance than those of the CLIC.

Key words: Lithium-ion capacitor, Pre-punched Cu foil, Prelithiation, SEI film, Current collector

MSC2000: 

  • O646