Could graphene construct an effective conducting network in a high-power lithium ion battery?

• Published in: Nano energy Vol. 1; no. 3; pp. 429 - 439
• Main Authors: Su, Fang-Yuan, He, Yan-Bing, Li, Baohua, Chen, Xue-Cheng, You, Cong-Hui, Wei, Wei, Lv, Wei, Yang, Quan-Hong, Kang, Feiyu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2012
• Subjects: Conducting network; Conductive additive; Graphene; High-power lithium-ion battery; Ion transport; Ion transport; High-power lithium-ion battery; Graphene; Conductive additive; Conducting network
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2012.02.004

This study is trying to demonstrate whether graphene is able to construct an effective conducting network for both electron and ion transports in cathode system of a high-power lithium ion battery (LIB), not based on a coin cell, but by employing a commercial soft-packaged 10Ah battery pack as a model system. Compared with the cells using commercial conductive additive (7wt% carbon black and 3wt% conductive graphite), a 10Ah cell using only 1wt% graphene and 1wt% carbon black shows lower internal resistance and higher energy density due to the excellent conductivity of graphene. However, owing to the fact that the planar structure of the graphene sheets blocks fast Li+ ion transport, the steric effect resulted heavy polarization occurs at a relatively high charge/discharge rate (>3C). That is, although flexible and planar graphene helps construct an effective electron transfer network, it retards Li+ ion transport. Thus, for an energy-storing LIB with a low working charge/discharge rate, graphene additive shows apparent superiority over commercial ones even with much less addition fraction and may find its real commercial applications; while, for a high-power LIB which works at higher charge/discharge rate, fast ion transport path is required to be effectively constructed before a real application. Simulation results indicate that further work should be focused on the adjustment of electrode pore structure and modification of graphene steric structure accordingly to construct an unimpeded ion conducting network and provide high speed path for Li+ ion transport. [Display omitted] ► Graphene is used as conductive additive in a commercial high-power 10Ah lithium ion battery. ► Planar structure of graphene blocks lithium ion transport at high rate. ► An electron conducting network is effectively constructed by graphene. ► Simulation shows the geometrical structure of graphene should be optimized.