Built‐In Electric Field Induced Uniform Li Deposition via Construction of CoP/Co2P Heterojunction in 3D Carbon Nanofiber Networks

Abstract Uncontrollable dendrite growth significantly hinders the application of Li metal anodes. To improve the uniformity of Li deposition, it is essential to develop an inorganic‐rich solid‐electrolyte interphase (SEI) and lithiophilic host surface. However, there exists a big challenge in simultaneously optimizing SEI and anode surface. Herein, the cobalt phosphide/dicobalt phosphide (CoP/Co 2 P) pp‐heterojunction modified carbon nanofiber networks (CNF‐CoP x ) are successfully prepared as 3D Li host, which can form built‐in electric field (BIEF) to accelerate the conversion reaction kinetics of CoP into Li 3 P, and spontaneously derive into a new BIEF induced by the Co/Co 2 P Schottky heterojunction facilitates the electron transfer during Li deposition process. Consequently, the CNF‐CoP x @Li symmetric cell exhibits impressive long‐term cycling stability, maintaining low polarization for up to 600 h at a current density of 3 mA cm −2 . Additionally, the CNF‐CoP x @Li||LiFePO 4 full cell delivers a high‐capacity retention of 89.5% over 500 cycles at 1 C.