Ionic Liquid-Mediated Mass Transport Channels for Ultrahigh Rate Lithium-Ion Batteries

New Insights into the Ion/Electron Transfer Mechanisms of LiMn2O4-Based Membrane Electrodes at Different Electron Fluxes

Electrochemical Li extraction technology is a highly promising approach for Li extraction from salt lakes. To enhance its practical application, it is crucial to elucidate the ion/electron transfer mechanism under diverse process conditions particularly different electron fluxes. Different migration intermediate states demonstrate the distinct ion migration mechanisms inside the LiMn2O4 lattice at different electron fluxes. Furthermore, direct observation of the distribution of Li+ in LiMn2O4-based membrane at different layered locations using Laser-induced Breakdown Spectroscopy (LIBS) reveals that the rate-limiting step is determined by the variety of electron flux. The desorption rate is limited by electron-transfer resistance at low electron fluxes whereas the ion-transfer resistance is the rate-limiting at high electron fluxes. These novel insights into the ion/electron transfer mechanisms and rate-limiting steps at different electron fluxes on the molecular and microscopic scales are imperative for the improvement of electroactive ion exchange materials (EIXMs) and practical applications of the electrochemical Li extraction technology.

Confined Ionic-Liquid-Mediated Cation Diffusion through Layered Membranes for High-Performance Osmotic Energy Conversion

Ion-selective membranes act as the core components in osmotic energy harvesting, but remain with deficiencies such as low ion selectivity and a tendency to swell. 2D nanofluidic membranes as competitive candidates are still subjected to limited mass transport brought by insufficient wetting and poor stability in water. Here, an ionic-liquid-infused graphene oxide (GO@IL) membrane with ultrafast ion transport ability is reported, and how the confined ionic liquid mediates selective cation diffusion is revealed. The infusion of ionic liquids endows the 2D membrane with excellent mechanical strength, anti-swelling properties, and good stability in aqueous electrolytes. Importantly, immiscible ionic liquids also provide a medium, allowing partial dehydration for ultrafast ion transport. Through molecular dynamics simulation and finite element modeling, that GO nanosheets induce ionic liquids to rearrange, bringing in additional space charges, which can be coupled with GO synergistically, is proved. By mixing 0.5/0.01 m NaCl solution, the power density can achieve a record value of ≈6.7 W m^-2 , outperforming state-of-art GO-based membranes. This work opens up a new route for boosting nanofluidic energy conversion because of the diversity of the ILs and 2D materials.