Porous-structured FeS2@C nanoparticles prepared from spent LiFePO4 cathodes with excellent rate performance for potassium-ion batteries

Recycling spent cathode materials is crucial for sustainably developing lithium-ion battery technology. To achieve the high-value utilization of spent LiFePO 4 (LFP) cathodes, this paper proposes a method for preparing MIL-100(Fe) based on solid waste residues from spent LFP cathodes. R-FeS 2 @C derived from MIL-100(Fe) can serve as an anode material for potassium-ion batteries featuring a porous structure. Electrochemical tests demonstrate that the R-FeS 2 @C exhibits more stable cycling performance compared with the FeS 2 @C derived from the traditional MIL-100(Fe), reaching 525 mAh g −1 after 100 cycles at a current density of 100 mA g −1 . Impressively, R-FeS 2 @C also showcases excellent rate performance (343 mAh g −1 specific capacity at 5 A g −1 ). Furthermore, full cells assembled with PI@rGO cathodes also exhibit excellent rate performance and stable cycling performance. The porous structure of R-FeS 2 @C provides numerous voids to accommodate volume changes and introduces sufficient channels for electrolyte penetration. The higher carbon content enhances the electrical conductivity improving the kinetics of the K + migration reaction. These researches can provide guidance for the recycling of spent lithium-ion batteries and the design of sulfide electrodes for PIBs.