Dual-functional indium doping enhances electronic/lithium-ion conductivity of LiFe0.4Mn0.6PO4 cathode for long cycling and high-rate performance

Lithium manganese iron phosphate has attracted extensive research attention as it retains the same advantages as lithium iron phosphate while delivering higher energy density. This research explores the dual effects of In 3+ doping in LiFe 0.4 Mn 0.6 PO 4 (LFMP) cathode material. Research results indicate that In 3+ enhances electronic conductivity by narrowing the LFMP bandgap from 3.334 eV to 2.222 eV and increasing the electron density near the Fermi level. Additionally, EIS and CV analyses consistently reveal a significant reduction in internal resistance and a notable decrease in electrode polarization. DFT calculations and further structural characterization through Rietveld refinement reveals that indium doping induces an elongation of Li O bonds while reducing the Li + migration barrier from 0.819 eV to 0.524 eV, thereby enhancing Li + diffusion kinetics. Electrochemical evaluation reveals that the In-doped LFMP delivers an initial capacity of 154.3 mAh·g −1 @ 0.1C with exceptional cycling stability (94.7 % retention @ 0.5C and 88.9 % retention @ 5C after 500 cycles). Remarkably, it maintains 117.6 mAh·g −1 even @ 5C, demonstrating significantly enhanced rate capability. These results demonstrate that In 3+ doping synergistically improves LFMP's electrochemical properties, suggesting excellent potential for advanced lithium-ion batteries. • Indium doping in LFMP enhances electronic/ionic conductivity to boost battery performance • Electronic conductivity is promoted by reduced bandgap and increased electron numbers • 1% In- LFMP exhibits capacity retention of 94.7% and 88.9% after 500 cycles at 0.5C and 5C • In 3+ doped LFMP displays improved diffusion kinetics from expanded Li-O bond length • 1% In- LFMP delivers a capacity of 117.6 mAh·g -1 @ 5C, outperforming that of LFMP