Deciphering the lithium storage chemistry in flexible carbon fiber‐based self‐supportive electrodes

Abstract Flexible carbon fiber cloth (CFC) is an important scaffold and/or current collector for active materials in the development of flexible self‐supportive electrode materials (SSEMs), especially in lithium‐ion batteries. However, during the intercalation of Li ions into the matrix of CFC (below 0.5 V vs. Li/Li + ), the incompatibility in the capacity of the CFC, when used directly as an anode material or as a current collector for active materials, leads to difficulty in the estimation of its actual contribution. To address this issue, we prepared Ni 5 P 4 nanosheets on CFC (denoted CFC@Ni 5 P 4 ) and investigated the contribution of CFC in the CFC@Ni 5 P 4 by comparing to the powder Ni 5 P 4 nanosheets traditionally coated on a copper foil (CuF) (denoted P‐Ni 5 P 4 ). At a current density of 0.4 mA cm −2 , the as‐prepared CFC@Ni 5 P 4 showed an areal capacity of 7.38 mAh cm −2 , which is significantly higher than that of the P‐Ni 5 P 4 electrode. More importantly, theoretical studies revealed that the CFC has a high Li adsorption energy that contributes to the low Li‐ion diffusion energy barrier of the Ni 5 P 4 due to the strong interaction between the CFC and Ni 5 P 4 , leading to the superior Li‐ion storage performance of the CFC@Ni 5 P 4 over the pristine Ni 5 P 4 sample. This present work unveils the underlying mechanism leading to the achievement of high performance in SSEMs.