Dually encapsulated LiMn0.6Fe0.4PO4 architecture with MXenes and amorphous carbon to achieve high-performance and ultra-stable lithium batteries†

Abstract

LiMn_xFe_1−xPO₄ (LMFP) materials, with their high energy density and excellent cycle stability, are promising cathode materials for electric vehicles and other high-energy-density applications. However, the low lithium-ion diffusion coefficient and poor electronic conductivity limit the further development of LMFP. In this study, we designed a strategy involving electrostatic self-assembly and in situ graphitization to fabricate a dense LMFP@MXene@C structure with dual encapsulation of LMFP (LiMn_0.6Fe_0.4PO₄). Owing to its high degree of graphitization, large surface area, excellent Li-ion directional transport, and dense dual encapsulation structure, the fabricated LMFP@MXene@C cathode exhibits a considerable reversible capacity (153.58 mA h g⁻¹ after 100 cycles at 1C) with outstanding rate performance and stability (maintaining 91.26% of its capacity after 1200 cycles at 5C). According to detailed TEM, in situ XRD techniques, and system dynamics and structural stability assessments analysis, the superior electrochemical stability and Li⁺ transport can be attributed to the network structure formed by 2D MXene layered channels and amorphous C layers. This structure facilitates rapid electron and ion transfer, effectively providing volumetric buffering and structural protection. The dual encapsulation strategy offers a feasible approach for the preparation of exceptional electrochemical cathode materials.