Enhancing Anode-Free Battery Performance with Self-Healing Single-Ion Conducting PAMPS-co-PBA Copolymer Interfaces

The design of anode-free batteries presents an attractive approach to the lithium metal battery. However, challenges such as uneven plating of lithium and poor Coulombic efficiency limit their commercially viable applications. In response to these challenges, this study introduces poly{(2-acrylamido-2-methylpropanesulfonic acid)-co-(butyl acrylate)} (PAMPS-co-PBA), an artificial interface engineered to enhance the cyclic stability of batteries by fortifying the solid electrolyte interphase (SEI) and enabling self-healing and single-ion conductivity. Synthesis outcomes, validated by FTIR and ¹H NMR spectra, demonstrate successful production of PAMPS-co-PBA. Experimental results, including analyses of surface morphology, tensile strength, and Li plating/stripping tests, demonstrate the effectiveness of PAMPS-co-PBA in preventing dendrite formation and achieving >99% Coulombic efficiency. SEM analysis reveals better surface morphology and minimal lithium deposits for PAMPS-co-PBA compared with bare copper and other alternative interfaces. XPS analysis confirms the self-healing and single-ion conducting attributes of PAMPS-co-PBA postcycling. Density functional theory calculations elucidates the interface's behavior, confirming a pathway for Li-ion movement facilitated by the sulfonic acid group. Ab initio molecular dynamics simulations highlight the potential for SEI formation, shedding light on the influence of LiTFSI on interface protection. Anode-free full cell testing demonstrates PAMPS-co-PBA enhancement in stability over bare copper, with 1.6 times capacity retention over 50 cycles, primarily attributed to self-healing and dendrite suppression. Nonetheless, observed capacity fading after prolonged cycling suggests the optimization of Li salt choice. Overall, PAMPS-co-PBA presents a promising solution for enhancing battery performance through advanced interface engineering.