Improved performance of the NaFePO4/Hardcarbon sodium-ion full cell

Abstract

Chronoamperometry and galvanostatic procedures were applied in the LiFePO4-based ion exchange approach for the production of NaFePO4 cathodes. The materials obtained by various processes were employed as the cathode electrode in Na-ion half cells, and their structural and electrochemical properties were investigated. According to XRD patterns for both processes, it is seen that the Na-ions were successfully replaced with Li-ions. In addition of this, XPS and EDX-dot mapping analyses were supports the ion exchange procedure. The electrochemical properties of the cathode were investigated using CR2032 cells, and the diffusion coefficient and diffusion activation energy were calculated using the CV graphs at various scan rates and environmental temperatures. It was found that the Na-diffusion rate in the cell is faster at higher temperatures than at lower temperatures. The galvanostatic cycling tests were performed for C/10 and 1C rates at room temperature, 10 °C, and 50 °C and determined that the first capacities for C/10 and 1C at room temperature were 140mAh/g and 60mAh/g, respectively, with good stability. The full cells of NaFePO4/hard carbon were fabricated by pre-sodiation technique and the battery performance tests revealed that the cells have a 74 mAh/g for C/10-rate with a voltage window of 2–4 V.