High-surface area active boron nitride nanofiber rich in oxygen vacancies enhanced the interface stability of all-solid-state composite electrolytes

Solid electrolytes are the most promising candidate for replacing liquid electrolytes due to their safety and chemical stability advantages. However, a single inorganic or organic solid electrolyte cannot meet the requirements of commercial all-solid-state batteries (ASSBs), which motivates the composite polymer electrolyte (CPE). Herein, a CPE of boron nitride nanofiber (BNNF) with a high specific surface area, rich pore structure, and poly (ethylene oxide) (PEO) are reported. Anions strongly adsorb on the surface of BNNF through electrostatic interactions based on oxygen vacancies, promoting the dissociation of lithium salts at the two-phase interface. The three-dimensional (3D) BNNF network provides three advantages in the CPE, including (i) improving ionic conductivity through strong interaction between polymers and fillers, (ii) improving mechanical properties through weaving a robust skeleton, and (iii) improving stability through a rapid and uniform thermal dispersion pathway. Therefore, the CPE with BNNF delivers high ionic conduction of 4.21 x 10-4 S cm-1 at 60 degrees C and excellent cycling stability (plating/stripping cycles for 20 0 0 h with a low overpotential of similar to 40 mV), which results in excellent electrochemical performance of LiFePO4 (LFP) full cell assembled with CPE-5BNNF-130 0 (152.7 mAh g-1 after 200 cycles at 0.5 C, and 134.8 mAh g-1 at 2.0 C). Furthermore, when matched with high-voltage LiNi0.6 Co0.2 Mn0.2 O2 (NCM622), it also exhibits an outstanding rate capacity of 120.4 mAh g-1 at 1.0 C. This work provides insight into the BNNF composite electrolyte and promotes its practical application for ASSBs. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.