Performance of full-cell Na-ion with NaNi1/3Mn1/3Co1/3O2 cathode material and different carbonate-based electrolytes

Abstract

The battery performance not only depend on the electrodes nature but also depend on the choice of electrolyte consisting of salts and organic solvents. The development of electrolytes compatible with both cathode and anode materials is essential for enhancing the performance of practical full-cell Na-ion batteries. Among electrode with difference Ni/Mn/Co ratio, NaNi1/3Mn1/3Co1/3O2 (NMC) showed the best stable cycling. Besides, carbonaceous anode materials such as hard carbon (HC) are attracting due to it low cost, high gravity/volumetric capacity. In this work, the electrochemical performance of full-cell Na-ion including NMC as cathode and HC as anode was studied in difference carbonate-based electrolytes with 2wt%FEC as additive. The cathode material was synthesized by sol-gel reaction following a calcination at 900oC for 12 hours. X-ray diffraction result of the synthesized sample indicates a layered structure with mutual O3 and P2 phase intergrowth and the dominant phase is O3. The impurity phase NiO also presents with negligeable content. In half-cell configuration with sodium metal anode, the material exhibited a typical staircase chargedischarge profile in various electrolytes. The highest capacity of 106 mAh/g with stable clycing up to 50 cycles was obtained in the electrolyte NaClO4 1 M/PC+2wt%FEC. However, this electrolyte couldn't enable the cycling the full-cell HC||NMC due to the incompatibility with HC anode. In consequence, the initial capacity of full-cell in this electrolyte was only 30 mAh/g and significantly decreased in consecutive cycles. Meanwhile, the electrolytes without PC or with low PC content tend to improve the charge/discharge capacity and the cycle life as well. Indeed, full-cell HC||NMC using NaClO4 1M/EC-DMC (1:1) + 2wt%FEC electrolyte exhibited the highest capacity of 90 mAh/g and excellent capacity retention (90% of the initial capacity) after 50 cycles. Additionally, the full-cell could deliver capacity of 55 mAh/g at high rate up to 2C.