The effect of graphene oxide (GO) on the mechanical properties and the curing reaction of Diglycidyl Ether of Bisphenol A/F and Triethylenetetramine epoxy system was investigated. GO was prepared by oxidation of graphite flakes and characterized by spectroscopic and microscopic techniques. Epoxy nanocomposites were fabricated with different GO loading by solution mixing technique. It was found that incorporation of small amount of GO into the epoxy matrix significantly enhanced the mechanical properties of the epoxy. In particular, model I fracture toughness was increased by nearly 50% with the addition of 0.1 wt. % GO to epoxy. The toughening mechanism was understood by fractography analysis of the tested samples. The more irregular, coarse, and multi-plane fracture surfaces of the epoxy/GO nanocomposites were observed. This implies that the two-dimensional GO sheets effectively disturbed and deflected the crack propagation. At 0.5 wt. % GO, elastic modulus was ∼35% greater than neat epoxy. Differential scanning calorimetry (DSC) results showed that GO addition moderately affect the glass transition temperature (T_g) of epoxy. The maximum decrease of T_g by ∼7 °C was shown for the nanocomposite with 0.5 wt. % GO. DSC results further revealed that GO significantly hindered the cure reaction in the epoxy system.

Lithium metal has been intensively investigated as a promising anode for next generation rechargeable Li metal batteries (LMBs). However, the safety concern on Li anodes caused by uncontrolled Li dendrite growth in liquid electrolytes hinders their application. Herein, a novel poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) based gel polymer electrolyte (GPE) with an asymmetric structure has been designed and developed to effectively retard the growth of lithium dendrites. Atomistic simulations confirm the strong interactions between PF₆ ⁻ and dipoles in the polymer matrix, which can anchor PF₆ ⁻ in the GPE and slow down its mobility to prevent space charge formation. In addition, this unique asymmetric membrane with a channel upper layer greatly enhances the mobility of Li⁺ in the GPE due to its low tortuosity and high porosity. The synergistic effect of the ion-dipole interaction and asymmetric structure increases the Li⁺ transference number to 0.66 and ionic conductivity to 3.36 mS cm⁻¹ (20 °C). Using this superior asymmetric GPE, Li|Li symmetric cells show more stable cycle performance than those using a liquid electrolyte. Li|LiFePO₄ batteries with the asymmetric GPE also deliver an impressive electrochemical performance, i.e., coulombic efficiency of 99.5% at 2C after 600 cycles. In consequence, this novel asymmetric GPE possesses potential application in high energy LMBs.