Synergistic intermolecular hydrogen-bonded cross-linking and steric hindrance effects enabling pomegranate-type LMFP@C for Li+ storage

Abstract

LiMn_xFe_1−xPO₄ is a promising cathode candidate due to its high security and the availability of a high 4.1 V operating voltage and high energy density. However, the poor electrochemical kinetics and structural instability currently hinder its broader application. Herein, inspired by the hydrogen-bonded cross-linking and steric hindrance effect between short-chain polymer molecules (polyethylene glycol-400, PEG-400), the pomegranate-type LiMn_0.5Fe_0.5PO₄-0.5@C (P-LMFP@C) cathode materials with 3D ion/electron dual-conductive network structure were constructed through ball mill-assisted spray-drying method. The intermolecular effects of PEG-400 promote the spheroidization and uniform PEG coating of LMFP precursor, which prevents agglomeration during sintering. The 3D ion/electron dual-conductive network structure in P-LMFP@C accelerates the Li⁺ transport kinetics, improving the rate performance and cycling stability. As a result, the designed P-LMFP@C has remarkable electrochemical behavior, boasting excellent capacity retention (98% after 100 cycles at the 1C rate) and rate capability (91 mAh·g⁻¹ at 20C). Such strategy introduces a novel window for designing high-performance olivine cathodes and offers compatibility with a range of energy storage materials for diverse applications.

Graphical abstract