Organic Molecular Intercalation Enabled Anionic Redox Chemistry with Fast Kinetics for High Performance Magnesium Storage

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 12; pp. e2308329 - n/a
• Main Authors: Deng, Rongrui, Wang, Zhongting, Tan, Shuangshuang, Lu, Guanjie, Huang, Xueting, Qu, Baihua, Huang, Guangsheng, Xu, Chaohe, Zhou, Xiaoyuan, Wang, Jingfeng, Pan, Fusheng
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-03-2024
• Subjects: anionic‐cationic simultaneous redox; Cations; Charge density; Electrochemical analysis; Electrode materials; Electrode polarization; Electrolytes; Electron transfer; Energy storage; Intercalation; interlayer organic molecule modulation; interlayer vacancy induction; Interlayers; layer spacing expansion; Magnesium; magnesium ion batteries (MIBs); Organic chemistry; Polyacrylonitrile; Reaction kinetics; Rechargeable batteries; Structural stability; magnesium ion batteries (MIBs); interlayer vacancy induction; layer spacing expansion; anionic‐cationic simultaneous redox; interlayer organic molecule modulation
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202308329

Rechargeable magnesium‐ion batteries possess desirable characteristics in large‐scale energy storage applications. However, severe polarization, sluggish kinetics and structural instability caused by high charge density Mg2+ hinder the development of high‐performance cathode materials. Herein, the anionic redox chemistry in VS4 is successfully activated by inducing cations reduction and introducing anionic vacancies via polyacrylonitrile (PAN) intercalation. Increased interlayer spacing and structural vacancies can promote the electrolyte ions migration and accelerate the reaction kinetics. Thanks to this “three birds with one stone” strategy, PAN intercalated VS4 exhibits an outstanding electrochemical performance: high discharge specific capacity of 187.2 mAh g−1 at 200 mA g−1 after stabilization and a long lifespan of 5000 cycles at 2 A g−1 are achieved, outperforming other reported VS4‐based materials to date for magnesium storage under the APC electrolyte. Theoretical calculations confirm that the intercalated PAN can indeed induce cations reduction and generate anionic vacancies by promoting electron transfer, which can accelerate the electrochemical reaction kinetics and activate the anionic redox chemistry, thus improving the magnesium storage performance. This approach of organic molecular intercalation represents a promising guideline for electrode material design on the development of advanced multivalent‐ion batteries.
The anionic redox chemistry in VS4 is successfully activated by inducing cations reduction and introducing anionic vacancies via polyacrylonitrile  intercalation. The increased interlayer spacing and structural vacancies can promote the electrolyte ions migration and accelerate the reaction kinetics, thus improving the magnesium storage performance.