A Novel Layered WO₃ Derived from An Ion Etching Engineering for Ultrafast Proton Storage in Frozen Electrolyte

Abstract

Aqueous proton batteries/pseudocapacitors are promising candidates for next‐generation electrochemical energy storage. However, their development is impeded by the lack of suitable electrode materials that facilitate rapid transport and storage of protons. Herein, an open‐layered hydrous tungsten oxide (WO3·nH2O) with larger layer spacing from Aurivillius Bi2WO6 via ion etching is proposed. Particularly, the WO3·nH2O electrode possesses a unique multi‐level nanostructure and presents superior rate performance (254 F g−1 at 1000 mV s−1, surpassing most carbon‐based electrode materials known). In situ X‐ray Diffraction combined with crystallography study demonstrate that the open layered structure with negligible structural strain enables fast and reversible (de)intercalation of protons during electrochemical reaction. Furthermore, a full proton pseudocapacitor (Prussian blue analogues//WO3·nH2O) operating in a wide temperature range from −40 to 25 °C is fabricated. This device can deliver 70% of the room‐temperature capacitance and stably cycle with negligible capacitance fading over 5000 cycles even in the solid‐phase electrolyte at −20 °C. This study provides a valuable strategy to design electrode materials with layered structures for the development of high‐performance aqueous proton batteries/pseudocapacitors at low temperatures.

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

“…At the ultra-low temperature, proton batteries with sulfuric acid electrolytes exhibited promising electrochemical performance [ 64 ]. In the 0.5 M H 2 SO 4 electrolyte, a Prussian blue analogues//WO 3 ·nH 2 O asymmetric proton pseudocapacitor not only exhibits extraordinary rate capacities and cycling stability for proton storage at room temperature, but also delivers 70% of the room temperature capacitance and long cycle life (99% capacitance retention over 5000 cycles) at −20 °C (solid-phase electrolyte) [ 65 , 66 ]. The MnO 2 @graphite felt//PTO proton full battery [ 19 ] operates well from −40 to −70 °C in frozen electrolytes of 2 M H 2 SO 4 .…”

Electrolyte and Electrode–Electrolyte Interface for Proton Batteries: Insights and Challenges

“…They can freely move and transport within the electrolyte, participating in the electrochemical reaction of the battery. [49] Transport and storage of protons in conjunction with the flow of electrical current in the system, facilitating energy conversion in the electrochemical proton storage (EPS) device. Proton can be transferred along the conjugated main chain of conductive polymers through the coupling of electrons, achieving energy storage.…”

“…The proton (H + ) generation through the hydrolysis of H 2 SO 4 serves as the charge carrier in PBs. They can freely move and transport within the electrolyte, participating in the electrochemical reaction of the battery [49] . Transport and storage of protons in conjunction with the flow of electrical current in the system, facilitating energy conversion in the electrochemical proton storage (EPS) device.…”

Polyaniline/Tungsten Trioxide Organic‐Inorganic Hybrid Anode for Aqueous Proton Batteries

“…Researchers are committed to developing new electrode materials for aqueous proton batteries. At present, organic materials such as carbonyl compounds, [27,28] anhydride compounds, [29,30] ketones compounds [28] and inorganic materials such as MoO 3 , [31][32][33][34] WO 3 [35][36][37] and Prussian blue analog [38] have been reported as feasible electrode materials choices for aqueous proton batteries. Among them, metal oxides with layered structures have large interlayer spacing, multiple valences and proper coordination environments which can bring excellent electrochemical performance.…”