Lithium storage behavior and mechanism of hexagonal FePO4/C composite as a novel anode material for lithium-ion batteries

Abstract

Exploring novel electrode materials is crucial for the development of high-performance lithium-ion batteries (LIBs). Herein, hexagonal FePO4/N-doped carbon (FP/C-600) composite is synthesized by a facile precipitation method and subsequent heat treatment process; the lithium ions storage performance and mechanism of hexagonal FePO4 as a novel anode material for LIBs are systematically investigated for the first time. The as-prepared FP/C-600 composite gives a high specific capacity (761.1 mA h g−1 at 0.2 A g−1), superior cyclability (433.5 mA h g−1 after 400 cycles at 0.5 A g−1), and outstanding rate capability (240.3 mA h g−1 at 5.0 A g−1) for a half cell. Ex-situ transmission electron microscopy (TEM) characterization demonstrates that the lithium storage reactions in the FePO4 anode proceed via a conversion reaction mechanism. The FP/C-600 nanocomposite has a much smaller electrochemical reaction resistance and larger Li+ diffusion coefficient than the pure FePO4 (FP-600) sample. More importantly, when evaluated as an anode material in a Li-ion full cell, the FP/C-600 composite still maintains a high specific capacity of 456.2 mA h g−1 after 50 cycles at 0.2 A g−1, implying that such FP/C-600 composite is a novel anode material with significant potential for future practical applications in LIBs.