Surface engineering of LiV3O8 with carbon quantum dots for enhanced electrochemical performance in sodium ion batteries

Abstract

LiV₃O₈ (LVO), a prominent layered oxide that has been extensively studied in lithium-ion batteries (LIBs), faces several challenges such as insufficient conductivity, irreversible phase transitions, structural collapse, and capacity degradation during charge-discharge cycles. These obstacles are further exacerbated in the context of sodium-ion batteries (SIBs), resulting in compromised cycle stability and rate performance, thereby hindering its application in SIBs. In this research, LVO/CQDs composites were efficiently prepared via a facile sonochemical method using carbon quantum dots (CQDs) modification. The uniform dispersion of CQDs on the LVO surface, while preserving its bulk structure, enhances electronic conductivity and cycle stability, Coulombic efficiency, and rate capability through morphology and dimensional optimization. In particular, the LVO/10%CQDs cathode exhibits an initial discharge capacity of approximately 185.4 mAh g⁻¹ at 30 mA g⁻¹ and retains 116.5 mAh g⁻¹ after 250 cycles, demonstrating remarkable cycling stability and rate capability. The integration of CQDs boosts the conductivity of LVO, reduces the internal resistance, increases the pseudo-capacitance contribution, enhances the Na⁺ diffusion coefficient, and significantly improves the electrochemical performance. Overall, this research presents a viable surface modification approach to enhance the electrochemical performance of layered metal oxides, potentially alleviating the challenges faced by LVO in SIBs.