Intermolecular Hydrogen-Bond Network Boosts Lithium-Bonding Kinetics in Solid-State Lithium Metal Batteries.

Abstract

Gel polymer electrolytes (GPEs) suffer from limitations such as low ionic conductivity, low lithium-ion transference number, and susceptibility to dendrite growth, hindering their widespread adoption in lithium metal batteries (LMBs). This work introduces an approach to enhance lithium-bonding kinetics by introduction of hydrogen bonds in GPE. The obtained weak intermolecular bonds eliminated the active hydrogen and controlled cross-linking of the GPE, which offered more ion transfer channels and a low ionic diffusion barrier and promoted coordination interaction. The resulting GPE achieves a high ionic conductivity of 10.57 × 10^-4 S cm^-1 and a transference number of 0.609. Furthermore, the free TFSI^- anion generated LiF-rich solid electrolyte interfaces (SEIs) with a satisfactory Young's modulus of 3.2 GPa, effectively guiding lithium-ion plating/stripping without dendrite formation. Notably, the incorporation of weak hydrogen bonding enables exceptional cycling stability in full cells by utilizing a LiFePO₄ cathode. The cells demonstrate a high specific capacity of ∼102.3 mA h g^-1 even after 1000 cycles at 3 C. This work highlights the impact of hydrogen bonding on regulating ion transport and SEI formation in LMBs, thereby facilitating the advancement of high-performance solid-state batteries.