The practical application of aqueous zinc‐ion batteries (AZIBs) is significantly limited by poor reversibility and stability of the Zn anode. Here, the first time addition of trace organic gamma butyrolactone (GBL) is reported to a typical ZnSO4 electrolyte to controllably manipulate the electrolyte structure and interface. Judiciously combined experimental characterization and theoretical computation confirm that the GBL additive weakens the bonding strength between Zn2+ ion and solvated H2O and rearranges the “Zn2+−H2O−SO42– GBL” bonding network to reduce water activity and suppress corrosion and side products. The GBL molecules preferentially absorb on the surface of the Zn anode to give a uniform and compact Zn deposition. As a result, the Zn anode is boosted to run over 3105 cycles (6210 h) with average Coulombic efficiency of 99.93% under 1 mA cm–2 and 1 mAh cm–2, and exhibit stable cycling for 1170 h under harsh testing conditions of 10 mA cm–2 and 10 mAh cm–2. Additionally, the Zn–MnO2 full cells using the ZnSO4–GBL electrolyte exhibit a high capacity of 287 mAh g–1 at 0.5 A g–1 and good capacity retention of 87% following 400 cycles. These findings will be of immediate benefit to design low cost AZIBs for clean energy storage.
The binder is an indispensable battery component that maintains the integrity of the electrode. Polyvinylidene fluoride (PVDF) is most commonly used as a binder in rechargeable batteries; however, it is associated with the toxic and expensive N‐methyl‐2‐pyrrolidone organic solvent. Here, through the cross‐linking of sodium alginate (SA) with metal cations, a high‐performance hydrogel binder is developed that maintains the stability of MnO2 cathodes in an aqueous electrolyte. Owing to the strong adhesion, high hydrophilicity, and good mechanical stability resulting from the strong bonding of Ca2+ with SA, a commercial microsized MnO2 cathode with a Ca−SA binder delivered a capacity above 300 mAh/g at 1 C, which was larger than those of Mn−SA and Zn−SA (∼200 mAh/g) and PVDF (∼150 mAh/g) binders, and a capacity of 250 mAh/g at 3 C for over 200 cycles. These encouraging results could unlock the enormous potential of aqueous binders for practical applications in aqueous batteries.
Mn3O4 powders with nanometer size are successfully synthesized by a simple one-step method via flame spray pyrolysis. The precursor droplet is generated by heating under high temperature flame with fixed flow rate, and the exothermic reaction is induced to form nanosized Mn3O4 powders. When used as anode material for lithium-ion battery, the Mn3O4 exhibits good cycling capacity and rate performance. It delivers a specific capacity of 1,182 mA h g−1 over 110 cycles at a current density of 200 mA g−1, and has a high capacity of 140 mA h g−1 at 5,000 mA g−1.
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