Optimizing the particle-size distribution and tap density of LiFePO4/C composites containing excess lithium

Abstract

LiFePO4 is a promising cathode material for lithium-ion batteries, but its inferior tap density leads to low-volumetric energy density of Li-ion batteries. This work reports that lithium amount can tune the particle-size distribution and tap density of the Li1 + xFePO4/C (x = 0–0.16) composites prepared via a wet chemistry method followed by carbon thermal reduction reaction. Excess lithium effectively prevents the agglomeration of primary particles, tunes the particle-size distribution, and thus improves the tap density of Li1 + xFePO4/C composite. The charge transfer resistance of the Li1 + xFePO4/C composite decreases with the increase of lithium amount. The Li1 + xFePO4/C composite with x = 0.12 exhibits a high tap density of 1.55 g cm−3 and a discharge capacity of 156 mAh g−1 at 0.1 C. Therefore, the tap density and electrochemical performance of LiFePO4/C composite could be conveniently tuned by lithium amount, indicating a facile and promising technique for LiFePO4/C composite preparation.