Sodium-ion batteries: Chemistry of biomass derived disordered carbon in carbonate and ether-based electrolytes

Abstract

Lightweight and low temperature processing carbon material as an anode are of attraction in upcoming sodium battery technology. Biomass is a natural resource and converting them to hard carbons (HC) is well known for their application as anode material. It favour's the cost and performance proposition in battery technology, however, suffers many fundamental problems like irreversible loss of sodium-ions in the first cycle, long-life stabilization, and quantification of defects on the carbon and electrochemical property correlation, etc. Many such factors are notably dependent on the electrolyte used, defects in hard carbons, so in consideration of that, the focus of our research is to spotlight this by studying the electrochemistry of biomass-derived carbon anode in two different electrolyte solvent systems namely, Carbonate-based(CB) and Ether-based(EB) electrolytes. The results obtained here suggest that the EB electrolyte is more efficient compared to the CB electrolyte and that the creation of a thin and homogenous SEI layer increased reversibility and storage performance. Further, a full-cell has been fabricated using our biomass-derived carbon anode against a known [Na 3 V 2 (PO 4 ) 3 (NVP)] sodium vanadium phosphate in the role of cathode with the optimized EB as an electrolyte and electrochemical performance has also been documented. SEI growth on the electrode surface has a big impact on cell performance and life. When comparing the performance of cells cycled in CB electrolyte and EB electrolyte, the latter showed promising results. The reason for the improved performance was examined, and two main reasons were found: unifrom SEI formation and reduced thickness of SEI formed on the electrode surface.