Unveiling the Mysteries: Acetonitrile's Dance with Weakly-Solvating Electrolytes in Shaping Gas Evolution and Electrochemical Performance of Zinc-ion Batteries.

Aqueous Zn-metal battery (AZMB) is a promising candidate for future large-scale energy storage with commendable capacity, exceptional safety characteristics, and low cost. Acetonitrile (AN) has been widely used as an effective electrolyte constituent to improve AZMBs' performance. However, its functioning mechanisms remain unclear. In this study, we unveiled the critical roles of AN in AZMBs via comparative in situ electrochemical, gaseous, and morphological analyses. Despite its limited ability to solvate Zn ions, AN-modulated Zn-ion solvation sheath with increased anions and decreased water achieves a weakly-solvating electrolyte. As a result, the Zn||Zn cell with AN addition exhibited 63 times longer cycle life than cell without AN and achieved a 4 Ah cm-2 accumulated capacity with no H2 generation. In V2O5||Zn cells, for the first time, AN suppressing CO2 generation, elevating CO2-initiation voltage from 2→2.44 V (H2: 2.43→2.55 V) was discovered. AN-impeded transit and Zn-side deposition of dissolved vanadium ions, known as "crosstalk," ameliorated inhomogeneous Zn deposition and dendritic Zn growth. At last, we demonstrated an AN-enabled high-areal-capacity AZMB (3.3 mAh cm-2) using high-mass-loading V2O5 cathode (26 mg cm-2). This study shed light on the strategy of constructing fast-desolvation electrolytes and offered insights for future electrolyte accommodation for high-voltage AZMB cathodes.

Water-in-Salt Gel Biopolymer Electrolytes for Flexible and Wearable Zn/Alkali Metal Dual-Ion Batteries.

Zn/alkali metal dual-ion batteries (ZM DIBs) with highly concentrated water-in-salt (WiS) electrolytes are promising next-generation energy storage systems. This enhanced design of Zn-ion rechargeable batteries offers intrinsic safety, high operating voltage, satisfactory capacity, and outstanding cyclic stability. Herein, taking the concept of highly concentrated electrolytes one step further, we introduce water-in-salt gel biopolymer electrolytes (WiS-GBEs) by encapsulating Zn/Li or Zn/Na bisalt compositions in a cellulose membrane. WiS-GBEs inherit the electrochemical merits of highly concentrated electrolytes (i.e., wide voltage window, high ionic conductivity, etc.) and excellent durability of gel biopolymer structures. Both types of WiS-GBEs apply to coin- and pouch-cell compartments of ZM DIBs, offering a high plateau voltage (>1.8 V vs. Zn2+/Zn), good and reversible capacity (118 and 57 mAh g-1 for Zn/Li and Zn/Na cells, respectively), and outstanding cycling stability (more than 90% after 1,000 cycles). Essentially, the pouch cells with WiS-GBEs present superior durability, flexibility, and capacity endurance under various bending stress conditions (90% capacity retention under 0-180° bending modes), indicating their potential capability to power wearable electronics. The practical powering ability of Li- and Na-based pouch systems is demonstrated by the example of a wearable digital timer.

Modification of chitin structure with tailored ionic liquids.

Chitin, poly N-acetylglucosamine, has a great potential for use on an industrial scale as an enzyme carrier but it has an unfavorable particle structure that can be modified using ionic liquids (ILs). Several ionic liquids were investigated that have the same substituents on the ring (methyl- and propyl-) but differed in the type of cationic ring (pyrrolidinium, piperidinium, and piperazinium). Organic acid ions (acetic and lactic) were used as counter ions. 1-ethyl-3-methyl-imidazolium acetate and 1-ethyl-3-methyl-imidazolium lactate were used as a reference. The results confirm that the chitin particle structure or size, or both, simultaneously changes if chitin is dissolved in an IL and then precipitated. Organic acid anions and short substituents on the cationic ring of ILs influenced particle modification substantially, whereas the type of ring played a minor role. Additionally, the ionic liquids [MPpyrr][OAc], [MPpip][OAc] and [DMPpz][OAc] could be reused up to at least 4 times without losing their ability to dissolve chitin.