Single-crystal Li-rich cathode Li_1.2Ni_0.2Mn_0.6O₂ for high-energy Li-ion batteries: molten salt-assisted combustion synthesis

Abstract

Lithium-rich manganese-based cathode material Li_1.2Ni_0.2Mn_0.6O₂ (LLNMO) has attracted widespread attention because of its high theoretical capacity and low cobalt content. However, its practical application is hindered by structural instability and rapid capacity decay during cycling. In this study, we present a novel synthesis method for single-crystal LLNMO using a LiCl+KCl mixed molten salt-assisted combustion method. Three types of LLNMO samples were comparatively investigated: polycrystalline particles, single-crystal particles prepared with LiCl, and single-crystal particles prepared with the LiCl+KCl mixed molten salt. Structural and morphological analyses reveal that the mixed molten salt-assisted single-crystal particles possess larger primary grains and a more robust crystal framework. Electrochemical characterization demonstrates that these particles exhibit superior cycling stability, minimal capacity fading, and reduced voltage decay. Specifically, the initial discharge capacity reaches 247.3 mAh · g⁻¹ at 0.1 C, with the lowest impedance and minimal polarization. This work highlights the effectiveness of mixed molten salt-assisted combustion in controlling particle morphology and improving the electrochemical performance of lithium-rich layered cathodes.

Keywords

Lithium-ion batteries / cathode / Li_1.2Ni_0.2Mn_0.6O₂ / Molten salt / Assisted combustion

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Central South University