MXene-Induced Adsorption of Transition Metals Stabilizes Lithium-Rich Manganese Cathodes against Voltage and Capacity Decay

Abstract

Lithium-rich manganese-based materials (LRMO) have emerged as ideal cathode materials for high-energy-density lithium-ion batteries due to their high capacity (>250 mAh/g) and low cost. However, the continuous migration and dissolution of transition metal ions (TMs) during cycling lead to severe voltage and capacity decay, limiting their application. This paper proposes a simple and efficient strategy: suppressing transition metal ion migration in LRMO by forming MXene thin layers to encapsulate the cathode or separator. This strategy leverages MXene’s adsorption capacity for Ni/Co/Mn (verified by density functional theory calculations). This adsorption reduces the migration of transition metal ions into the electrolyte or cathode, thereby mitigating complex cross-effects while simultaneously creating locally Mn-rich regions that thermodynamically suppress the irreversible phase transition of LRMO. Concurrently, MXene’s excellent conductivity optimizes the cathode’s charge–discharge kinetics. Consequently, the MXene-encapsulated LRMO cathode electrode demonstrated outstanding cycling performance (87.16% capacity retention after 200 cycles at 0.1C, 25 °C; and 87.36% at 0.5C after 200 cycles) and reduced voltage decay. This MXene encapsulation strategy offers an approach to enhancing the comprehensive electrochemical performance of LRMO cathode lithium-ion batteries.