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 LiPF6 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 PF6− anions, affording the GPE a high ionic conductivity and a high Li+-ion transference number (0.77). When assembled into Li|electrolyte|LiFePO4 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.
All Science Journal Classification (ASJC) codes
- Materials Science(all)