리튬화 기능성 전도성 첨가제를 통한 LiFePO₄ 양극의 고속충방전 성능 향상

초록

LiFePO4 (LFP) has been extensively used as a safe and cost-effective cathode material for lithium-ion batteries. However, its intrinsically low electronic conductivity (~10-9 S/cm-1) and limited one-dimensional Li+ diffusion led to poor high-rate performance, necessitating the development of efficient conductive networks and interfacial modifications. To overcome these limitations, we introduced a Lithiated Functionalized Conductive Additive (LFCA) incorporating lithium-substituted groups as a multifunctional conductive additive. The ionophilic lithium-substituted functional groups promote enhanced charge transfer and Li+ transport at the electrode?electrolyte interface, while simultaneously providing additional Li+ diffusion pathways through a uniformly dispersed conductive matrix. As a result, the LFCA-modified LFP cathode exhibits a significantly reduced charge/discharge voltage gap, indicating improved reaction kinetics and lower polarization. Electrochemical Impedance Spectroscopy (EIS) confirmed a notable decrease in charge-transfer resistance, validating the enhanced ionic and electronic conductivity. Furthermore, the formation of a LiF-rich SEI layer stabilized the electrode interface, leading to improved rate capability and stable cycle behavior. These enhancements originate from the synergistic effects of the lithiated functional groups and the conductive carbon framework, which collectively promote efficient Li+ transport and charge transfer across the electrode. This approach demonstrates that functionalized conductive additives offer scalable and practical solutions to improve rate performance and durability in LFP cathodes for high power lithium-ion batteries.