Triggering Ion Diffusion and Electron Transport Dual Pathways for High Efficiency Electrochemical Li+ Extraction.

Abstract

Efficient electrochemical Li+ adsorption holds significant promise for lithium extraction, while the mismatched rate between Li+ diffusion and electron transport within the electrode material impedes the electrochemical activity and restricts the adsorption efficiency. To address this challenge, herein, we rationally design and integrate the ion and electron dual-conducting poly(vinyl alcohol)-polyaniline (PVA-PANI) copolymer (CP) within the H1.6Mn1.6O4 (HMO) electrode matrix to facilitate Li+ diffusion and electron transport. The Li+ diffusion coefficient (DLi+) increased from 3.03 × 10-10 to 5.92 × 10-10 cm2/s, while the charge transfer resistance (Rct) decreased from 53.73 to 29.57 ohm. Consequently, the HMO@CP electrode exhibits superior adsorption kinetics and a state-of-the-art high adsorption capacity of up to 49.48 mg/g. Comprehensive mechanistic studies reveal that the negatively charged hydroxyl groups (-OH) in PVA accelerate Li+ diffusion and that the conjugated structure and redox-active quinoid sites in PANI offer denser electron distribution and promote electron transport. This synergistic effect in CP significantly enhanced Li+ diffusion and electron transport, leading to electrochemical activity and adsorption efficiency. Our work highlights the critical role of simultaneously regulating the ion diffusion and electron transport dual pathways for optimizing Li+ adsorption performance and inspires development of the next generation electrochemical adsorption electrodes.