Issue 13, 2018, Issue in Progress

Chemical reaction characteristics, structural transformation and electrochemical performances of new cathode LiVPO4F/C synthesized by a novel one-step method for lithium ion batteries

Abstract

A new cathode LiVPO4F/C with a high working voltage of around 4.2 V was synthesized by a novel one-step method. The color of the solution turns green, which implies that V2O5 is successfully reduced to V3+. The reaction thermodynamics indicates that LiVPO4F/C is formed when the sintering temperature is higher than 650 °C, while the accompanying impurity phase Li3V2(PO4)3/C is also generated. The reaction kinetics proves that the reaction is third order and the activated energy is 208.9 kJ mol−1. X-ray photoelectron spectra imply that the components of LiVPO4F/C prepared at 800 °C (LVPF800) are in their appropriate valence. LVPF800 is composed of micron secondary particles aggregating from nano subglobose. The structural transformation shows that the V : P : F ratio in LVPF800 is close to 1 : 1 : 1. The reason behind generation of impurity Li3V2(PO4)3 at a high temperature of 850 °C is demonstrated directly, which is mainly due to the volatilization of VF3. The electrochemical performances of the cathode are related to the crystallite content of LiVPO4F/C and Li3V2(PO4)3/C. The specific capacities at 0.2 and 5C of LVPF800 are as high as 139.3 and 116.5 mA h g−1. Electrochemical analysis reveals that LVPF800 possesses an excellent reversibility in the extraction and insertion process and minimum charge transfer resistance.

Graphical abstract: Chemical reaction characteristics, structural transformation and electrochemical performances of new cathode LiVPO4F/C synthesized by a novel one-step method for lithium ion batteries

Article information

Article type
Paper
Submitted
12 Jan 2018
Accepted
02 Feb 2018
First published
13 Feb 2018
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2018,8, 7044-7054

Chemical reaction characteristics, structural transformation and electrochemical performances of new cathode LiVPO4F/C synthesized by a novel one-step method for lithium ion batteries

Q. Li, Z. Wen, C. Fan, T. Zeng and S. Han, RSC Adv., 2018, 8, 7044 DOI: 10.1039/C8RA00370J

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