New Highly Stable Ionic Compounds Composed of Multivalent Graphene Quantum Dot Anions and Alkali Metal Cations. Issue 3 (23rd December 2021)

• Record Type: Journal Article
• Authors: Chul Lim, Hong; Kim, Min‐Cheol; Kim, Ayoung; Park, Eunji; Park, Yunjae; Chang, Rakwoo; Hong, Jong‐In; Park, Kyung‐Won; Shin, Ik‐Soo; Kim, Hansu
• Is Part Of: Batteries & supercaps. Volume 5:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-23
• Subjects: electrochromic device -- electrolyte salt -- graphene quantum dot -- ionic compound -- lithium-ion battery; Electrochemistry -- Periodicals; Electrodes -- Periodicals; Electric batteries -- Periodicals; 621.31242
• DOI: 10.1002/batt.202100337
• Languages: English
• ISSNs: 2566-6223

Abstract

Abstract: Developing electrolytes with new chemical structures that simultaneously satisfy excellent ionic conductivity, chemical stability, and thermal stability is an indispensable prerequisite for studying next‐generation electrochemical. Herein, we propose a new class of ionic compounds consisting of graphene quantum dots (GQD) polyanions with alkali metal cations. The synthesized solid salts readily dissolve in various solvents ranging from water to carbonates allowing highly conductive liquid electrolytes for electrochemical systems. Molecular dynamics simulation with the electrochemical characterization reveals that the ionic compounds provide highly abundant free metal cations with highly stable GQD polyanions, and negligible ion pairs in solution. The lithium salt (Li‐GQD) shows higher lithium transference number than the conventional LiPF6 electrolyte, which improves the interfacial stability of Li metals and leads to a decrease in overvoltage at a high C‐rate in battery performance. The Li‐GQD electrolyte solution offers a wide electrochemical window of −0.2−5 V, which can reliably apply to various electrode materials (graphite, Li4 Ti5 O12, and LiCoO2 ). Prussian blue thin film utilizing K‐GQD as electrolyte shows significantly improved electrochromic behaviour and higher K + cation mobility than other controls using conventional electrolytes. We expect our study on the GQD ionic complex to be another signpost for exploring an innovative electrolyte for electrochemical devices. Abstract : Multivalent polyanionic electrolyte : The graphene quantum dot (GQD) polyanion and alkali metal cations show a high dissociation rate and transport number for an electrolyte. The M‐GQD electrolyte delivers a more favorable electrochemical performance of devices such as lithium‐ion batteries and electrochromic systems.