Preparation and characterization of the Li1.12K0.05Mn0.57Ni0.24Nb0.02O2 cathode material with highly improved rate cycling performance for lithium ion batteries

Abstract

In this work, Li_1.12K_0.05Mn_0.57Ni_0.24Nb_0.02O₂ (LMN–K/Nb) as a novel and high energy density cathode material is successfully synthesized and applied in lithium ion batteries. By combining interlayer exchange and elemental analysis, it can be confirmed that K⁺ and Nb⁵⁺ substitution is respectively in the lithium layer and transition metal (TM) layer since H⁺ replaces the cations that remain in the lithium layer rather than those in the TM layer. The effect of K⁺ and Nb⁵⁺ co-substitution on the kinetic behavior of insertion/extraction of Li⁺ is evaluated by electrochemical impedance spectroscopy (EIS), the galvanostatic intermittent titration technique (GITT) and galvanostatic charge/discharge (GCD). LMN–K/Nb delivers an initial capacity of 145 mA h g⁻¹ at 5C rate and 112 mA h g⁻¹ at 10C rate, and maintains 83.1% after 400 cycles at 5C rate and 82.5% at 10C rate. By post-mortem analysis of long-term cycled LMN–K/Nb, K⁺ and Nb⁵⁺ are recognized to play a role in suppressing the irreversible side reactions in LLOs during cycling. This work demonstrates that dual elemental substitution into the lithium layer and TM layer is a feasible strategy to enhance the performance of LLO cathode materials.