Construct Stable Charge Carrier Transport Interface for High-Energy-Density Electrodes by Grafting Ion-Conducting...

Carbon materials are the key additives for electronic conductivity in electrodes, which determine the electrochemical performances and durability of batteries. Herein, a strategy for grafting ion-conducting groups to multi-wall carbon nanotubes (MWCNTs) is proposed via in situ polymerization induced by a Lewis acid agent BF₃, which is generated from the disproportionation of LiBC₂O₄F₂ (LiODFB). The as-obtained MWCNTs demonstrate a narrower particle size distribution in the solution due to the reduced surface defects and steric effect between the grafted oxyethylene (EO) segments. Moreover, the MWCNTs with ion-conducting groups (CNT-EO) show not only good electronic/ionic dual conductivity but also high chemical- and electrochemical- stability up to 4.8 V with the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) electrode. The CNT-EO integrates the cathode into a monolithic structure through an interconnected 3D dual conductive network, which accelerates the construction of a robust LiF-dominated interphase layer on NCM811. Therefore, the Li/NCM811 cells with CNT-EO additive deliver a high discharge capacity of 183.5 mAh g^-1 at 0.5 C, and a significantly improved cycle life of 400 cycles. The strategy of grafting special functional groups to the CNTs is beneficial to construct a stable charge carrier transport interface for electrodes with high-energy density, long life, and high safety.