Minimization of Ion–Solvent Clusters in Gel Electrolytes Containing Graphene Oxide Quantum Dots for Lithium‐Ion Batteries

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 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|LiFePO 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.

Development of the PEO Based Solid Polymer Electrolytes for All-Solid State Lithium Ion Batteries

“…Lithium-ion batteries (LIBs), as the most significant candidates for energy storage devices, have quickly occupied the global electrical consumer market due to their relatively high energy density, advanced operating voltage, and lack of a memory effect [1,2,3,4]. However, conventional LIBs with organic liquid electrolytes (OLEs) possess some inherent drawbacks, such as flammability, leakage, and environmental toxicity, which hinder their application in Electric Vehicles (EVs) or air-planes who need energy storage devices with high energy densities and, more importantly, high safety [5,6,7,8]. In this regard, replacing OLEs with all solid electrolytes (ASEs) seems to be a reliable solution for the aforementioned safety issues [9,10].…”

The effects of hydroxide and epoxide functional groups on the mechanical properties of graphene oxide and its failure mechanism by molecular dynamics simulations

“…Graphene xide (GO) is a graphene derivative with different amounts of hydroxyl and epoxy groups attached to the surface, and carboxyl groups distributed on the edge. Owing to its excellent mechanical, physical properties and chemical modi-cation ability, it has promising applications in a wide range of areas, such as, polymer reinforced composites, 1 super capacity, 2 exible electronic devices, 3 lithium ion batteries, 4 and so on. In general, GO is synthesized by either the Brodie, 5 Staudenmaier, 6 or Hummers method, 7 or some variation of these methods.…”

Inorganic Fillers in Composite Gel Polymer Electrolytes for High-Performance Lithium and Non-Lithium Polymer Batteries

“…This study demonstrated the decrease in crystallinity of porous PVDF due to the homogeneously dispersed graphene in host polymer, resulting in the increased GPE electrolytic conductance from 1.85 × 10 0 mS cm −1 in pure PVDF to 3.61 × 10 0 mS cm −1 in the presence of 0.002 wt% graphene, and enhanced cyclic performance of the cell. Chen et al [ 167 ] studied a GPE that consists of PAVM as a host polymer, LiPF 6 as a source of Li + ion, and GO quantum dots (GOQD) as an inorganic filler. The GOQD hinders the formation of ion-solvent clusters and immobilizes anions; as a result, the assembled LiFePO 4 /GPE/Li cell showed a good performance at high rates (up to 20 C) and exhibited capacity retention of 100% after 500 cycles.…”