oa NASICON based Na4MnV PO4 3/MWCNTs Cathode Materials for Naion Batteries with Improved Electrochemical Performance

Lithium ion batteries (LIBs) have completely captured the portable electronics and electric vehicle market due to their tempting performance. However, due to limited reserves of lithium, the price for lithium is constantly increasing which necessitates to trace out some decent alternative to lithium ion batteries. In this regard, sodium ion batteries are considered one of the best substitutes for lithium ion batteries due to inherited properties of sodium metal like abundance of resources across the globe, ease of availability, economy and environmentally friendly nature. Moreover, sodium ion batteries follow the similar electrochemical principles as the lithium ion batteries which indicates that knowledge and understanding of principles of lithium ion batteries can be utilized for the development of smart sodium ion batteries. In this work NASICON (Na+ super ionic conductor) based Na4MnV (PO4) 3 was synthesized using the sol - gel technique. As prepared Na4MnV (PO4)3 demonstrates an active redox couple at around 3.6 V and 3.2 V during oxidation and reduction process respectively. The pristine Na4MnV(PO4)3 shows good initial discharge capacity ∼ 138 mAh g-1 at 0.05C. However, it shows rapid discharge capacity fading with increasing discharge rate (138 mAh/g at 0.05C and 15 mAh/g at 2C) and poor cycling performance (68.0% of the initial capacity was retained after 40 cycles) with increasing discharge rate. To improve the electrochemical performance of the developed material, Na4MnV (PO4)3/MWCNTS (MWCNTs = 1 & 3wt. %) were synthesized. The initial discharge capacity of these materials at 0.05C was found to be similar to pristine Na4MnV(PO4)3, however, the addition of MWCNTs has resulted in significant improvement in the discharge capacity at high c-rate which can be mainly attributed to the enhanced electronic conductivity of the pristine material. Apart from higher capacity at high c-rates, the addition of MWCNTs has also improved the cyclability of the pristine Na4MnV(PO4)3. A capacity retention of 99.0 % and 98.00% of the initial discharge capacity after 40 cycles is noticed for Na4MnV(PO4)3/1wt.%MWCNTs and Na4MnV(PO4)3/3wt.%MWCNTs respectively. The improved performance of Na4MnV (PO4) 3/MWCNTs cathode materails make them attractive for energystorage applications.