Tailoring Acid-Salt Hybrid Electrolyte Structure for Stable Proton Storage at Ultralow Temperature

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Developing ultralow-temperature proton energy storage faces challenges in charge carrier diffusion and water-induced side reactions.
• Existing electrolytes struggle with performance degradation and interfacial instability at sub-zero temperatures.

Purpose of the Study:

• To design and demonstrate an acid-salt hybrid electrolyte with a stable solvation structure for unconventional proton transport at ultralow temperatures.
• To achieve high rate-capacity and stable electrode interfaces in proton-based energy storage devices operating at -80°C.

Main Methods:

• Developed an acid-salt hybrid electrolyte by introducing ZnCl2 into a 0.2 M H2SO4 solution.
• Utilized multiscale simulations and experimental investigations to analyze the electrolyte's solvation structure and proton transport.
• Employed in situ XRD and spectroscopic techniques to study electrode-electrolyte interface stability.

Main Results:

• The hybrid electrolyte exhibits a stable anion-cation-H2O solvation structure, creating favorable water network channels for rapid proton transport at ultralow temperatures.
• The electrolyte's 3D network structure immobilizes free water, inhibiting deleterious electrode distortion and ensuring outstanding cycling stability.
• VHCF//α-MoO3 hybrid proton capacitors achieved a capacity of 39.8 mAh g-1 at 1 A g-1 and -80°C, with 96% capacity retention after 1500 cycles.

Conclusions:

• The designed anti-freezing hybrid electrolyte enables efficient proton transport and stable interfaces at ultralow temperatures.
• This work provides an effective strategy for advancing energy storage applications in extreme cold environments.