Acid‐in‐Clay Electrolyte for Wide‐Temperature‐Range and Long‐Cycle Proton Batteries

Abstract

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−1 at 25 °C, 0.023 mS cm−1 at −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.

Pre‐Protonated Vanadium Hexacyanoferrate for High Energy‐Power and Anti‐Freezing Proton Batteries

“…3+ and H 2 O, the hydrogen bond within water molecules is seriously damaged as the H 3 PO 4 concentration increases, thus preventing the construction of ice crystals and reducing the freezing point of electrolyte. [38,39] The ionic conductivity of the electrolyte decreases when concentration is greater than 8.5 M, which may be caused by the increase in viscosity. Hence, 8.5 M H 3 PO 4 was directly used as the electrolyte of H-VHCF// MoO 3 /MXene proton battery for electrochemical testing at low-temperature.…”

Rational Design of Electrode–Electrolyte Interphase and Electrolytes for Rechargeable Proton Batteries

“…e Schematic diagram and f SEM image of acid-in-clay electrolytes. Inset of f : photograph by a camera [ 80 ]. Copyright 2022, Wiley–VCH …”

“…To overcome the issue of corrosion, broaden the electrolyte potential window and inhibit the solvent-electrode interactions, solid and quasi-solid electrolytes have attracted recent research interest. A novel family of solid proton electrolytes (acid-in-clay electrolyte) have been reported recently by Wang et al [ 80 ] via integrating proton charge carriers in a natural phyllosilicate clay network that can be manufactured into thin-film (tens of microns) fluid-impervious membranes (Fig. 7 e, f).…”

“… Solid proton batteries are promising because protons can transport rapidly via the special Grotthuss conduction in solid electrolytes, compared with metal-ion solid batteries with inferior ionic conductivity. Currently, there is only one report about the acid-in-clay film [ 80 ]. More investigations on solid proton electrolytes are highly needed.…”

Nanosecond protonic programmable resistors for analog deep learning

“…Figure 4D shows that the Si L 2,3 energy-loss spectra were similar in active and inactive regions across the PSG layer, which indicates that there was no stoichiometry change or that the change was too subtle to be detected. Considering that the widest electrochemical stability window for room temperature protonic electrolytes was previously ~3.35 V ( 55 ), we attribute our devices’ ability to operate stably and reversibly at 10 V/−8.5 V to the operation at nanosecond transients, where the PSG does not have to conform to the thermodynamic stability requirement for electrolytes (established after quasi-static wait times). Furthermore, these short time scales may simply be too fast for oxygen motion (slower than that of protons), which would otherwise cause degradation of material properties.…”