Construction of La-doped BiFeO3 ferroelectric heterojunction coatings to enhance the performance of lithium-rich manganese-based cathode materials

Abstract

Lithium-rich manganese-based cathodes exhibit ultra-high capacities (>250mAh g⁻¹) due to high operating voltage and multiple redox mechanisms, making them ideal for high-energy–density lithium-ion batteries. However, challenges such as oxygen loss, parasitic reactions, and structural degradation limit their practical application. To address these issues, a Bi_1-xLa_xFeO₃ (0 < x ≤ 0.2) ferroelectric heterointerface layer is constructed, effectively suppressing side reactions, enhancing lattice oxygen reversibility, and preventing structural degradation. The piezoelectric effect induced by volumetric changes further promotes Li⁺ transport and diffusion. The modified cathode achieves remarkable cycling stability, retaining 176.6mAh g⁻¹ (88.39 %) at 1C and 194.5mAh g⁻¹ at 0.5C (86.52 %) after 200 cycles, with reduced voltage decay (0.6 V to 0.4 V). Even at a high current density of 5C, a capacity of ∼ 120mAh g⁻¹ is maintained. This study provides a new design strategy for durable, high-energy–density layered oxide cathodes.