Binder and conductive diluents free NaVPO4F based free-standing positive electrodes for sodium-ion batteries. Issue 1 (12th January 2022)

• Record Type: Journal Article
• Authors: Kumar, V. Kiran; Ghosh, Sourav; Naresh, Vangapally; Ummethala, Govind; Malladi, Sai Rama Krishna; Martha, Surendra K.
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 1(2022)
• Publication Date: 2022-01-12
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac47eb
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Herein, we report a carbon-fiber-based freestanding electrode for NaVPO4 F cathodes in sodium-ion batteries. The replacement of conventional aluminium foil with a carbon fiber mat-based current collector results in significant improvement in capacity at high rates and charge-discharge cycle stability. Petroleum-pitch (P-Pitch) has dual functions. P-pitch is used as a binder to bind NaVPO4 F particles onto the carbon fiber mat, which helps to eliminate typical organic binders. At the same time, P-Pitch acts as a conducting precursor to coat onto NaVPO4 F particles. The amount of P-pitch required to achieve stable electrochemical performance is optimized. As a result, 15 and 20% of P-pitch in the composite NaVPO4 F electrodes (15P_NVPF@CF and 20P_NVPF@CF) shows stable electrochemical performances. A reversible capacity of 120 and 119 mAh g −1 is observed for 15P_NVPF@CF and 20P_NVPF@CF, with 97 and 98% retention in capacity after 300 cycles, respectively. Further, at a 0.5 C current rate, 15P_NVPF@CF and 20P_NVPF@CF electrodes show 86 and 87% capacity retention after 1000 cycles. The significant electrochemical performance of these freestanding electrodes is ascribed to the interlinked carbon matrix with NaVPO4 F particles and carbon-fiber mat, which provides a continuous path for electronic conduction and faster kinetics of NaVPO4 F particles.