Construct Stable Charge Carrier Transport Interface for High‐Energy‐Density Electrodes by Grafting Ion‐Conducting Group to Carbon Nanotube Additives

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.