Delicate synthesis of quasi-inverse opal structural Na_(3)V_(2)(PO_(4))_(3)/N-C and Na4MnV(PO_(4))_(3)/N-C as cathode for high-rate sodium-ion batteries

摘要

Poor conductivity and sluggish Na^(+) diffusion kinetic are two major drawbacks for practical application of sodium super-ionic conductor(NASICON) in sodium-ion batteries. In this work, we report a simple approach to synthesize quasi-inverse opal structural NASICON/N-doped carbon for the first time by a delicate one-pot solution-freeze drying-calcination process, aiming at fostering the overall electrochemical performance. Especially, the quasi-inverse opal structural Na_(3)V_(2)(PO_(4))_(3)/N-C(Q-NVP/N-C) displayed continuous pores, which provides interconnected channels for electrolyte permeation and abundant contacting interfaces between electrolyte and materials, resulting in faster kinetics of redox reaction and higher proportion of capacitive behavior.As a cathode material for sodium-ion batteries, the Q-NVP/N-C exhibits high specific capacity of 115 mAh·g^(-1) at 1C, still 61 mAh·g^(-1) at ultra-high current density of 100C,and a specific capacity of 89.7mAh·g^(-1) after 2000 cycles at 20C.This work displays the general validity of preparation method for not only Q-NVP/N-C,but also Na_(3)V_(2)(PO_(4))_(3),which provides a prospect for delicate synthesis of NASICON materials with excellent electrochemical performance.