Liquid-exfoliated graphene as highly efficient conductive additives for cathodes in lithium ion batteries

We demonstrate in this work that the liquid-exfoliated graphene produced by jet cavitation as conductive additives can greatly improve the electrochemical performance of commercial cathode materials in lithium ion batteries (LIBs). It is found that a graphene loading of similar to 3 wt% can increase the specific capacity from 150 to 178 mAh/g in LiFePO4. For LiCoO2 and Li(Ni1/3Mn1/3Co1/3)O-2, adding graphene results in a maximum specific capacity of 156 and 168 mAh/g, respectively, which is significantly enhanced when compared to the commercial materials without graphene. The merit of graphene conductive additives is attributed to 'point-to-plane' conductive network formed by the combination of OD acetylene black and 2D graphene flakes. The conductive network reduces the internal resistance of cathodes, and meanwhile does not cause obvious voltage polarization or block the diffusion path of lithium ions. This study creates new opportunities for fabricating high-performance LIB cathodes by using low-cost liquid-exfoliated graphene. (C) 2019 Elsevier Ltd. All rights reserved.