PEGDA-based nanocomposite gel polymer electrolytes with hydroxylated h-BN nanosheets enabling fast ion transport and high-voltage stability for lithium metal batteries

Despite their favorable interfacial contact and high ionic conductivity, gel polymer electrolytes (GPEs) remain constrained by insufficient electrochemical and thermal/mechanical stability as well as low lithium-ion transference numbers, restricting their long-term application in lithium metal batteries (LMBs). In this study, a poly(ethylene glycol) diacrylate (PEGDA) based nanocomposite gel polymer electrolyte (NGPE-BN-x) was developed by thermal in situ polymerization, incorpo rating a few-layer hydroxylated hexagonal boron nitride nanosheets (h-BNNS-OH) as a two-dimensional (2D) nanofiller. The influence of h-BNNS-OH loading (1, 3, and 5 wt%) on lithium ion transference number (tLi +), ionic conductivity, electrochemical, thermal and mechanical stability was systematically evaluated relative to the pristine GPE. The optimized NGPE-BN-3 exhibited high ionic conductivity (σ = 8.85 mS cm− 1), an expanded electrochemical stability window (ESW) of 5.01 V, an enhanced tLi + of 0.66, and improved mechanical strength (0.64 MPa) at room temperature. LFP//Li full cells utilizing NGPE-BN-3 yielded a discharge capacity of 162.2 mAh g− 1 at 0.1 C with good rate capability (0.1-2.0 C), and prolonged cycling stability at 1 C under ambient conditions. The improved electrochemical performance highlights the effectiveness of h-BNNS-OH as a multifunctional additive for PEGDA-based GPEs toward high-performance LMBs.