A Prussian Blue-Derived Dual-Functional Precursor for High-Performance LFP/C Cathodes

Olivine LiFePO₄ (LFP) is regarded as a particularly viable cathode for lithium-ion batteries and is distinguished by its remarkable thermal safety, long-term cycling performance, and favorable environmental profile. Nevertheless, the implementation of this material in high-power applications remains constrained by inherently poor electrical conductivity and sluggish kinetics of lithium-ion transport. Conventional carbon-coating strategies generally rely on external carbon sources, whereas this study proposes a novel dual-functional precursor approach using Prussian blue (PB, Fe₄[Fe(CN)₆]₃) as both iron and carbon sources to synthesize carbon-coated LFP (LFP/C) via a one-step sintering process. Electrochemical evaluations show that the synthesized material displays an excellent initial discharge capacity of 160.3 mAh·g^-1 at 0.2C and retains 119.1 mAh·g^-1 even under a high-rate condition of 6C. Upon returning to 0.2C, the capacity rebounds to 160.9 mAh·g^-1, reflecting exceptional rate performance and structural reversibility. Furthermore, capacity retentions of 96.7% and 84.3% are achieved after 500 cycles at 1C and 5C, demonstrating remarkable long-term cycling stability. These performance enhancements originate from the in situ formed carbon layer and highly ordered structure derived from the PB precursor. The former establishes an efficient electron-conducting network and suppresses particle growth, while the latter promotes the formation of uniformly distributed particles, facilitating electrolyte infiltration and lithium-ion transport. This work confirms that the use of PB as a dual-functional precursor constitutes a straightforward and efficient approach to synthesizing high-performance LFP/C, providing a new pathway for developing high-performance lithium-ion batteries.