ABSTRACT
Polymer electrolytes (PEs) have been thoroughly investigated due to their advantages that can prevent severe problems of Li-ion batteries, such as electrolyte leakage, flammability, and lithium dendrite growth to enhance thermal and electrochemical stabilities. Gel polymer electrolytes (GPEs) using in situ polymerization are typically prepared by thermal or UV curing methods by initially impregnating liquid precursors inside the electrode. The in situ method can resolve insufficient interfacial problems between electrode and electrolyte compared with the ex situ method, which could led to a poor cycle performance due to high interfacial resistance. In addition to the abovementioned advantage, it can enhance the form factor of bare cells since the precursor can be injected before polymerization prior to the solidification of the desired shapes. These suggest that gel polymer electrolytes prepared by in situ polymerization are a promising material for lithium-ion batteries.
ABSTRACT
We demonstrate a gel polymer electrolyte (GPE) featuring a crosslinked polymer matrix formed by poly(ethylene glycol) diacrylate (PEGDA) and dipentaerythritol hexaacrylate (DPHA) using the radical photo initiator via ultraviolet (UV) photopolymerization for lithium-ion batteries. The two monomers with acrylate functional groups undergo chemical crosslinking, resulting in a three-dimensional structure capable of absorbing liquid electrolytes to form a gel. The GPE system was strategically designed by varying the ratios between the main polymer backbone (PEGDA) and the crosslinker (DPHA) to achieve an optimal gel polymer electrolyte network. The resulting GPE exhibited enhanced thermal stability compared to conventional liquid electrolytes (LE) and demonstrated high ionic conductivity (1.40 mS/cm) with a high lithium transference number of 0.65. Moreover, the obtained GPE displayed exceptional cycle performance, maintaining a higher capacity retention (85.2%) comparable to the cell with LE (79.3%) after 200 cycles.