materials in dilute aqueous electrolytes, respectively, [7] although a common strategy for adjusting the operating window is to change the pH of the electrolyte. However, even in strongly alkaline electrolytes (pH = 14), hydrogen evolution still occurs at 2.213 V, which is too high to accommodate most of the anode materials desired by battery scientists. [8] Additionally, a downshift in O 2 evolution potential will occur simultaneously when the pH is increased, keeping the gap between the anodic and cathodic limits constant at 1.23 V. This gap, known as the electrochemical stability window in aqueous electrolytes under thermodynamic equilibria, is defined by the Pourbaix diagram. The slightly higher voltage gap of 1.8 V that has been realized in existing aqueous battery setups is the result of "kinetic overpotentials" of H 2 or O 2 evolutions, which depends on changing the salt concentration, catalytic activity of the electrodes, and applied currents. [9] As a result, very few suitable electrode materials have been reported for AIBs at present, and their energy densities are still far from those required for practical applications. A particular challenge is that O 2 or H 2 evolution will result in low energy efficiencies, which is of vital importance for this technology. [10] The working potential of lithium-ion battery electrode materials is also far beyond the thermodynamic stability limits of organic electrolytes. [11] Hence, solvent molecules coordinated with Li + to form solvation shells can suffer from decomposition when ions move between electrode surfaces during the charging/discharging processes. These decomposition reactions produce dense, solid products that deposit on electrode surfaces to form a solid-electrolyte interface (SEI), which prevents direct contact between the electrodes and electrolytes. [12] A large number of inorganic salts or precipitates originating from salt reductions may also be present in the SEI at the anode, making it insulating to long-range electron transport but conductive to ions. Therefore, it can prevent sustained electrolyte decomposition while still allowing electrochemical reactions to proceed. The presence of an SEI substantially expands the usable electrochemical stability window of nonaqueous electrolytes. [13] However, protective interfaces are not formed in conventional aqueous electrolytes, because the decomposition products from coordinated water mostly are gases such as H 2 and O 2 , which will escape from the electrolyte on formation. [2] Unfortunately, traditional inorganic lithium salts such as Li 2 SO 4 , LiCl, and LiNO 3 are stable enough to be reduced Aqueous lithium/sodium-ion batteries (AIBs) have received increasing attention because of their intrinsic safety. However, the narrow electrochemical stability window (1.23 V) of the aqueous electrolyte significantly hinders the development of AIBs, especially the choice of electrode materials. Here, an aqueous electrolyte composed of LiClO 4 , urea, and H 2 O, which allows the electrochemical stability windo...

Aqueous rechargeable Zn/birnessite batteries have recently attracted extensive attention for energy storage system because of their low cost and high safety. However, the reaction mechanism of the birnessite cathode in aqueous electrolytes and the cathode structure degradation mechanics still remain elusive and controversial. In this work, it is found that solvation water molecules coordinated to Zn2+ are coinserted into birnessite lattice structure contributing to Zn2+ diffusion. However, the birnessite will suffer from hydroxylation and Mn dissolution with too much solvated water coinsertion. Through engineering Zn2+ primary solvation sheath with strong‐field ligand in aqueous electrolyte, highly reversible [Zn(H2O)2]2+ complex intercalation/extraction into/from birnessite cathode is obtained. Cathode–electrolyte interface suppressing the Mn dissolution also forms. The Zn metal anode also shows high reversibility without formation of “death‐zinc” and detrimental dendrite. A full cell coupled with birnessite cathode and Zn metal anode delivers a discharge capacity of 270 mAh g−1, a high energy density of 280 Wh kg−1 (based on total mass of cathode and anode active materials), and capacity retention of 90% over 5000 cycles.

The practical application of aqueous rechargeable batteries is hampered by the low energy density and poor cycle stability, which mostly arises from the corrosion of cathode current collector, exfoliation of active material, and narrow electrochemical stability window of aqueous electrolyte. A light‐weight and low‐cost cathode current collector composed of graphite and carbon nanotube coated on nylon membrane exhibiting corrosion resistance and strong adhesion is developed. Also, a modified aqueous electrolyte with the addition of urea whose window is expanded to ≈3.2 V is developed that contributes to the formation of solid‐electrolyte interphase on surfaces of electrodes. LiMn2O4/NaTi2(PO4)3 Li+/Na+ hybrid ion battery using such aqueous electrolyte and current collector is demonstrated to cycle up to 10 000 times with low cost (60 dollars per kWh) and high energy density (100 Wh kg−1) for stationary energy storage and electronic vehicles applications.

Hierarchical MoSe2@C hollow nanospheres are synthesized via an anion-exchange reaction and exhibit good electrochemical performance.

Chemodynamic therapy (CDT), a newly developed approach for cancer treatment, can convert hydrogen peroxide (H2O2) into toxic hydroxyl radicals (•OH) by using Fenton/Fenton-like reaction to kill tumor cells. However, due to the complexity of the intracellular environment of tumor cells, the therapeutic efficacy of CDT was severely restricted. Recently, combination therapy strategies have become popular approaches for tumor treatment, and there are numerous studies have demonstrated that the CDT-based combination strategies can significantly improve the anti-tumor efficiency of CDT. In this review, we outline some of the recent progress in cancer chemodynamic therapy from 2020, and discuss the progress in the design of nanosystems for CDT synergistic combination therapies.