Search for: All records

Solid polymer electrolytes (SPEs) have the potential to meet evolving Li‐ion battery demands, but for these electrolytes to satisfy growing power and energy density requirements, both transport properties and electrochemical stability must be improved. Unfortunately, improvement in one of these properties often comes at the expense of the other. To this end, a “hybrid aqueous/ionic liquid” SPE (HAILSPE) which incorporates triethylsulfonium‐TFSI (S_2,2,2) orN‐methyl‐N‐propylpyrrolidinium‐TFSI (Pyr_1,3) ionic liquid (IL) alongside H₂O and LiTFSI salt to simultaneously improve transport and electrochemical stability is studied. This work focuses on the impact of HAILSPE composition on electrochemical performance. Analysis shows that an increase in LiTFSI content results in decreased ionic mobility, while increasing IL and water content can offset its impact. pfg‐NMR results reveal that preferential lithium‐ion transport is present in HAILSPE systems. Higher IL concentrations are correlated with an increased degree of passivation against H₂O reduction. Compared to the Pyr_1,3systems, the S_2,2,2systems exhibit a stronger degree of passivation due to the formation of a multicomponent interphase layer, including LiF, Li₂CO₃, Li₂S, and Li₃N. The results herein demonstrate the superior electrochemical stability of the S_2,2,2systems compared to Pyr_1,3and provide a path toward further enhancement of HAILSPE performance via composition optimization.

Proton conduction underlies many important electrochemical technologies. A family of new proton electrolytes is reported: acid‐in‐clay electrolyte (AiCE) prepared by integrating fast proton carriers in a natural phyllosilicate clay network, which can be made into thin‐film (tens of micrometers) fluid‐impervious membranes. The chosen example systems (sepiolite–phosphoric acid) rank top among the solid proton conductors in terms of proton conductivities (15 mS cm⁻¹at 25 °C, 0.023 mS cm⁻¹at −82 °C), electrochemical stability window (3.35 V), and reduced chemical reactivity. A proton battery is assembled using AiCE as the solid electrolyte membrane. Benefitting from the wider electrochemical stability window, reduced corrosivity, and excellent ionic selectivity of AiCE, the two main problems (gassing and cyclability) of proton batteries are successfully solved. This work draws attention to the element cross‐over problem in proton batteries and the generic “acid‐in‐clay” solid electrolyte approach with superfast proton transport, outstanding selectivity, and improved stability for room‐ to cryogenic‐temperature protonic applications.

A comprehensive study on the prototype solid solution phase carbonitride MXene Ti₃CN is conducted using nuclear magnetic resonance, electron spin resonance, total and quasi‐elastic neutron scattering, combined with density functional theory‐based electronic structure and molecular dynamic calculations. The combination of experiment and theory lead toward rational atomic structural models of Ti₃CN. The remnant Al ions from the etching process significantly tune the interlayer spacing, distinct from the more typical MXene, Ti₃C₂, prepared similarly. Neutron scattering indicates the surface terminations of Ti₃CN display high oxygen and fluorine concentrations and rather low hydroxyl and hydrogen concentrations. Calculations show that the structure including both the residual Al ions and mixed surface terminations give the best agreement with the measurements. The water molecules in Ti₃CN are highly immobile, in strong contrast to those in Ti₃C₂. The analysis of the electronic structure suggests that the nitride MXene displays higher conductivity than the carbides. The absence of hydroxyl groups in terminations, the solid‐solution in the anion sites, the remnants within layers, and immobile water altogether make the carbonitrides a unique series in the MXene family, implying a further exploration of their exotic properties and applications in energy storage.