Enhanced electrochemical performances of LiFePO₄-C synthesized with PEG as the grain growth inhibitor for Li-ion capacitors in LiNO₃ aqueous electrolyte

Abstract

Purpose The purpose of this paper is to conduct the synthesization of LiFePO4-C (LFP-C) with fine particle size and enhanced electrochemical performance as the positive electrode material for Li-ion capacitors (LICs) with neutral aqueous electrolyte. Design/methodology/approach LFP-C was prepared by using polyethylene glycol (PEG) as a grain growth inhibitor, and the effects of the calcination temperature and PEG content on the structure and morphology of LFP-C were investigated. LICs using environment-friendly, safe and low-cost LiNO3 aqueous electrolyte were assembled with LFP-C as the positive electrode and active carbon as the negative electrode. The electrochemical performances of LFP-C and LICs were studied. Findings The results show that the particle size of LFP-C decreases significantly through the introduction of PEG. Cyclic voltammetry results show that the LFP-C prepared at 550°C with 1.0 g PEG exhibits the highest Cpe of 725 F/g at the scanning rate of 5 mA/s. Compared to LFP prepared without PEG, the electrochemical performance of optimized LFP-C dramatically increases due to the decrease of the particle size. Moreover, the LIC assembled with the optimized LFP-C exhibits excellent electrochemical performances. The LIC maintains about 91.3 per cent of its initial Cps after 200 cycles which shows a good cycling performance. Research limitations/implications The LFP-C is the suitable positive electrode material for LICs with neutral aqueous electrolyte. LICs can be used in the field of automobiles and can solve the problems of energy shortage and environmental pollution. Originality/value Both the LFP-C with fine particle size and its optimal LIC using environment-friendly, safe and low-cost LiNO3 aqueous electrolyte own good electrochemical performances.

Enhanced electrochemical performance of LiFePO4 of cathode materials for lithium-ion batteries synthesized by surfactant-assisted solvothermal method

“…It has an important impact on the morphology and size of the prepared materials, which are crucial for determining electrochemical performance [34,35]. It has been reported that the grain size and morphology of the prepared samples can be well controlled by adding suitable surfactants in the solvothermal reaction process [36][37][38][39].…”