Enhancing Li⁺ Kinetics Via Selective Repulsion-Adsorption and Intermolecular Ion-Conduction Layers for High-Energy-Density Anode-Free Lithium-Metal Batteries.

Abstract

Anode-free lithium-metal batteries, offer high energy density, but suffer from limited lifespan due to sluggish Li⁺ desolvation at the anode. Conventional artificial layers on the anode attract Li⁺ by polar groups, yet inadvertently accumulate solvent molecules near these polar layers, impede desolvation, and form an organic-rich solid electrolyte interphase (SEI) with low ionic conductivity. Herein, a selective repulsion-adsorption strategy is proposed, achieved using a layer (MS layer, 35 nm) comprising polystyrene sulfonic acid (PSS) and montmorillonite (MMT). During electrospray fabrication, the PSS self-assemble, with non-polar benzene rings and C-H main chains facing outward, while the -SO₃ ^- groups are buried underneath. The non-polar components can repel polar solvent molecules, and negatively charged MMT will absorb Li⁺, suppressing solvent accumulation and facilitating desolvation. Meanwhile, the anions attracted by MMT will form an inorganic-rich SEI with superior ionic conductivity. Furthermore, the PSS-MMT interface forms a rapid Li⁺ transport pathway with reduced migration barriers. Consequently, anode-free MS-Cu||LFP cells operate over 350 cycles, increasing ≈200% compared with Cu||LFP cells. Additionally, 2 Ah anode-free MS-Cu||LFP (340 Wh kg^-1) and MS-Cu||NCM811 pouch cells (490 Wh kg^-1) maintain 80% capacity after 100 and 50 cycles. This work presents an efficient strategy to enhance Li⁺ kinetics for high-performance batteries.