• Energy Research

Aqueous energy storage devices attract increased attention due to their high safety, low cost, and easy maintenance. However, the low energy density caused by the narrow electrochemical stability window (ESW) of aqueous electrolytes severely restricts their widespread applications. Herein, a new type of “small‐molecule crowding” electrolyte of 95EG‐H2O (95 wt% ethylene glycol [EG]) is proposed for the first time. Significant enhancement of water molecular stability is accomplished through the engineering of a hydrogen bond network. The small‐molecular crowding agent (EG) not only expands the ESW to 3.2 V, but also endows the electrolyte with low viscosity. As a proof‐of‐concept device, the symmetry carbon‐based supercapacitor using the newly developed electrolyte exhibits a so far record‐high operating voltage of 2.8 V, a high energy density of 58.7 Wh kg−1 at a power density of 1.4 and 30.3 Wh kg−1 at a power density of 42 kW kg−1, and a durable lifespan exceeding 20 000 cycles at a current density of 5 A g−1.

A recyclable P/FS-Z inorganic/organic hybrid separator with a unique regulation capability of hydrophilicity and hydrophobicity is designed for the first time for aqueous zinc metal batteries.

An ultra-dense biomimetic bone hydrogel with a seamless interfacial structure was designed for aqueous batteries and on-skin monitoring systems.

Hard carbon (HC) is the most promising anode material for sodium‐ion batteries (SIBs). The main obstacle to HC's application is its incompatibility with the phosphate flame‐retardant additive, a common SIB additive. This incompatibility arises from the unstable solid electrolyte interphase (SEI) caused by phosphate molecule decomposition. For the first time, in this work, a new type of highly adaptive flame‐retardant electrolyte is proposed. The electrolyte ensures the stability of the electrode/electrolyte interface by the introduction of pioneering long‐chain nitrile as the SEI‐forming additive and solvated structural regulator. Long‐chain nitriles decompose before phosphate and form a stable SEI containing N element, which prevents the phosphate from inserting into the HC's layers and reduces its sodium‐storage capacity. As a proof of concept, the HC anode demonstrates a higher initial Coulombic efficiency of 80.78% in the as‐designed highly adaptive flame‐retardant electrolyte, which is about 1.8 times than that before regulation. It can cycle stably for 1250 cycles at 3 C with a capacity retention of 60%. Moreover, the electrolyte has good flame retardancy and can extinguish naturally within 1 s. In this work, an innovative method is provided for developing high‐safety SIBs based on HC anodes.