SYNTHESIS AND EVALUATION OF Ti3C2 MXENE ENCRYPTED NASICON Na3V2(PO4)2F3 FLUOROPHOSPHATE AND THEIR PERFORMANCE IN A SODIUM SYMMETRIC CELL

Abstract

Lithium (Li) based battery materials are facing the harsh challenges of high cost and resource limitation. Sodium (Na) based materials are a futuristic solution to the field of energy storage materials. The symmetric battery materials, in which the same material can be used as cathode and anode, provide a futuristic solution to the field of energy storage. The fluorophosphate-based NASICON material Na3V2(PO4)2F3 (NVPF), with its two redox couples, works as a perfect symmetric battery material. The low intrinsic electronic conductivity of the NVPF hinders its performance. In this work, the MXene 2D material with the properties of excellent electrical conductivity is incorporated with NVPF to overcome this drawback. This work combines the benefit of the NASICON material with the layered MXene structure and results in the MXene encrypted symmetric battery material. The NVPF with MXene encryption is a first of its kind study, and the nano material was synthesized using a facile sol-gel method using Ti3C2 MXene and was analyzed for its structural and electrochemical features and tested in a symmetric full-cell configuration. The assembled full cell gives a specific discharge capacity of 54mAhg-1 at 1C for 2wt% MXene composition and 94mAhg-1 at 1C for 5wt% MXene composition as compared to 43.75mAhg-1 for pristine NVPF with respect to cathode weight. The rate capability of the material has also been improved, as indicated by electrochemical studies. The electrochemical impedance spectroscopy results indicate lowered bulk resistances for the MXene 5wt% sample. The diffusion coefficient of Na+ during discharge was calculated as 4.14x10-9 cm2s-1 for the pristine sample and 9.57 x 10-9 cm2s-1 for the 5wt% MXene sample.