Metal–organic framework-derived LiFePO4/C composites for lithium storage: In situ construction, effective exploitation, and targeted restoration

Abstract

Hitherto, LiFePO₄ (LFP) is bottlenecked by inferior electronic conductivity and sluggish Li⁺ diffusion, which can be resolved by cation doping, morphological engineering, carbon coating, and so forth. Among these methodologies, morphological optimization and carbon modification can warrant a stable operating voltage and prolong the cycling lifespan, which can be accessible by utilizing metal–organic frameworks as self-sacrificing templates. Herein, we conceptualize a strategy to in-situ construct N-doped carbon-coated LFP with Prussian blue analogues as the template, after which electrochemical tests extensively exploit the lithium storage capacity with 153.2 mAh g⁻¹ after 500 cycles at 0.5 C. However, the capacity failure associated with the inevitable Li⁺ loss and destructed carbon layer provides sufficient room for the restoration of LFP after long-term cycling. Motivated by this, the cell performance of LFP/C after targeted restoration using the 3,4-dihydroxybenzonitrile dilithium salt is investigated, revealing a considerable recovered capacity due to the recuperative LFP crystal and uniform carbon layer with homogeneous N-distribution. The computational study also supports the feasibility of N-doped carbon layer in LFP modification. This study envisages a methodology for the performance improvement of LFP from directional fabrication to targeted recovery, providing insights into the manufacturing and reuse of LIB cathodes.