Facile fabrication of compact LiFePO4/C composite with excellent atomically-efficient for high-energy-density Li-ion batteries

LiFePO4 is a highly competitive cathode material for electric vehicles and grid-scale energy storage due to its good safety, durability and affordability. In this work, an optimized solid-state synthesis route is developed to prepare low-cost and high-performance LiFePO4/C composite with iron powder as direct raw material. The precursor containing Li3PO4, Fe powder and FePO4 not only renders a 100% atomic economy, but also avoids the gas generation from raw materials and suppresses the pore formation during the solid-state calcination process, thus leading to a high tap density of ~1.45 g cm−3 that is 30% higher than commercial LiFePO4/C. Physicochemical and electrochemical characterizations reveal that the Fe powder size and ball milling duration affect the cell performance significantly based on the effect of precursor uniformization. With balanced cost and performance, the optimized conditions realize a high volumetric capacity of 200.3 mAh cm−3 at 1 C, good rate capability up to 5 C, and more importantly a considerable 16.0% enhancement of energy affordability compared with commercial counterpart (2.03 vs. 1.75 Wh L−1 USD−1). Moreover, further electrode compaction enables a remarkable energy density of 1012.5 Wh L−1 at electrode level, demonstrating a great promise in advancing LiFePO4-based lithium-ion batteries for practical applications.