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Proton‐based energy storage systems provide a more sustainable alternative for large‐scale energy storage applications. However, conventional proton batteries/pseudocapacitors suffer from severe capacity loss because of reduced ionic conductivity and water‐to‐ice conversion at ultralow temperatures. Here, anti‐freezing proton‐rich electrolytes with ultralow freezing point (below −80 °C) and high conductivity (7.89 mS cm−1 at −80 °C) are developed, combined with open framework‐structured Prussian blue analogous (VHCF) electrodes with proton‐rich binding sites, to construct a promising proton pseudocapacitor at ultralow temperatures. Hydrogen bond‐induced solvated structures and physicochemical properties are clarified by comprehensive characterization techniques and computational simulations. Temperature‐dependent structure and valence changes for VHCF electrodes at low temperatures are revealed, where the multi‐electron transfer reaction is affected by temperature to limit the capacity output. The proton pseudocapacitor (VHCF//6 m H2SO4//MoO3‐x) achieves excellent electrochemical performance in the temperature range from −80 to 25 °C, and delivers a voltage window of 0 to 2.8 V and a high energy density of 74.9 Wh kg−1 at −80 °C. This proton‐rich electrolyte‐electrode design principle suggests an effective strategy enabling next‐generation energy technology under extreme conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Lithium ion capacitors (LICs) as promising energy storage devices are receiving lots of attention recently. However, anodes with high rate performance are urgently needed to balance the thermodynamics and kinetics of the cathode and the anode. Here, we report a morphology structure strategy to enhance the rate properties of disordered rock-salt Li3V2O5 (DRS-LVO) based on crystal phase engineering. Li3V2O5 nanospheres (LVO-NSs) deliver a low average insertion voltage (∼0.6 V vs. Li+/Li), excellent rate capability, and outstanding cycling stability (more than 85% capacity is retained after 6000 cycles) in half-cell devices. The electrode kinetics study shows that the novel nanosphere morphology endows LVO-NSs with more capacitive capacity contribution and a rapid ion transport path. The first-principles calculations indicate the energy storage and transport mechanism of LVO-NSs, in which Li+ migrates into the lattice along the (110) plane with the lowest energy. A LIC with outstanding electrochemical performance is assembled by using LVO-NSs as the anode and active carbon as the cathode, delivering an energy density of 61.9 W h·kg−1 at a power density of 12.75 kW·kg−1. This electrode design strategy of synergistic morphology and crystal structure provides a new route for the development of high-power and long-life energy storage devices. [ABSTRACT FROM AUTHOR]

Electrochemical proton storage provides high energy, fast kinetics, safety, and environmental friendliness for grid‐scale energy storage. However, the development of pseudocapacitive proton supercapacitors with fast chargeability and high stability is still challenging because of the unclear electrochemical reaction mechanism and unsuitable construction strategy. Here it is shown that a multi‐metallic Prussian blue analog—Cu0.82Co0.18HCF, which possesses enhanced electronic structure and ion transport path—can intercalate/de‐intercalate large amounts of proton at high rates. Ion‐induced transformation of magnetism, fast solid‐state proton transport, and reversible insertion/de‐insertion of protons lead to extremely excellent rate capacities and cycling stability for proton storage. An asymmetric pseudocapacitive proton supercapacitor (Cu0.82Co0.18HCF//WO3·nH2O) is fabricated with a voltage window of 1.7 V, delivering a maximum energy density of 35 Wh kg−1 and an energy density of 22 Wh kg−1 at a high power density of 26 kW kg−1. Combining systematical material design and mechanism study, this work not only broadens the preparation of electrode materials but also brings light to the construction of high‐performance devices for efficient proton storage. [ABSTRACT FROM AUTHOR]

Zinc‐ion batteries (ZIBs) have been regarded as one of the most promising aqueous energy storage devices due to their low‐cost, high capacity, and intrinsic safety. However, the relatively low Coulombic efficiency caused by the dendrite formation and side reactions greatly hinders the rejuvenation of ZIBs. Here, an utterly simple approach by pencil drawing is employed to improve the poor performance of normal Zn anode and hinders the formation of passivated byproduct as well as serious dendrite growth. Significantly, the functional graphite layer can not only act as ions buffer, but also guide the uniform nucleation of Zn2+ in graphite voids. With such synergy effect, the graphite‐coated Zn anode (Zn–G) displays low overpotential, high reversibility, and dendrite‐free durability compared with the pristine Zn. Consequently, a low voltage hysteresis of ≈28 mV can be achieved and maintained over 200 h. Furthermore, the Zn–G anode is paired with a V2O5·xH2O cathode to construct a rechargeable ZIB. As‐assembled device can output high energy/power density of 324.3 Wh kg−1/3269.8 W kg−1 (based on the active mass loading in cathode) together with a capacity retention of ≈84% over 1500 cycles at a current density of 5 A g−1. [ABSTRACT FROM AUTHOR]