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Minimization of Ion–Solvent Clusters in Gel Electrolytes Containing Graphene Oxide Quantum Dots for Lithium‐Ion Batteries
Author(s) -
Chen YenMing,
Hsu ShihTing,
Tseng YuHsien,
Yeh TeFu,
Hou ShengShu,
Jan JengShiung,
Lee YuhLang,
Teng Hsisheng
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201703571
Subject(s) - graphene , materials science , electrolyte , oxide , lithium (medication) , ionic conductivity , inorganic chemistry , battery (electricity) , solvent , quantum dot , chemical engineering , nanotechnology , chemistry , organic chemistry , electrode , medicine , endocrinology , engineering , metallurgy , power (physics) , physics , quantum mechanics
Abstract This study uses graphene oxide quantum dots (GOQDs) to enhance the Li + ‐ion mobility of a gel polymer electrolyte (GPE) for lithium‐ion batteries (LIBs). The GPE comprises a framework of poly(acrylonitrile‐ co ‐vinylacetate) blended with poly(methyl methacrylate) and a salt LiPF 6 solvated in carbonate solvents. The GOQDs, which function as acceptors, are small (3−11 nm) and well dispersed in the polymer framework. The GOQDs suppress the formation of ion−solvent clusters and immobilize P F 6 −anions, affording the GPE a high ionic conductivity and a high Li + ‐ion transference number (0.77). When assembled into Li|electrolyte|LiFePO 4 batteries, the GPEs containing GOQDs preserve the battery capacity at high rates (up to 20 C) and exhibit 100% capacity retention after 500 charge−discharge cycles. Smaller GOQDs are more effective in GPE performance enhancement because of the higher dispersion of QDs. The minimization of both the ion−solvent clusters and degree of Li + ‐ion solvation in the GPEs with GOQDs results in even plating and stripping of the Li‐metal anode; therefore, Li dendrite formation is suppressed during battery operation. This study demonstrates a strategy of using small GOQDs with tunable properties to effectively modulate ion−solvent coordination in GPEs and thus improve the performance and lifespan of LIBs.