High-Voltage and Stable Manganese Hexacyanoferrate/Zinc Batteries Using Gel Electrolytes

Because of the high safety and environmental friendliness,aqueouszinc-ion batteries have gained a lot of attention in recent years.Prussian blue and its analogues are regarded as a promising cathodematerial of zinc-ion batteries. Manganese hexacyanoferrate is appropriateamong them due to its high operating voltage, large capacity, andcheap price. However, the poor cycling stability of manganese hexacyanoferrate,mainly caused by transition metal dissolution, side reaction, andphase transition, greatly restricts its practical application. Inthis work, gelatin is used to limit the content of free water in theelectrolyte, thus reducing the dissolution effect of transition metalmanganese. The introduction of gelatin improves the durability ofthe Zn anode as well. The optimized MnHCF/gel-0.3/Zn battery displaysa high reversible capacity (120 mAh center dot g(-1) at0.1 A center dot g(-1)), an excellent rate performance (42.7mAh center dot g(-1) at 2 A center dot g(-1)),and a good capacity retention (65% at 0.5 A center dot g(-1) after 1000 cycles).

Automated summary

Due to its high safety and environmental friendliness, aqueous zinc-ion batteries have attracted much attention recently. Prussian blue and its analogues are regarded as promising cathode materials. Among them, manganese hexacyanoferrate is suitable due to its high operating voltage, large capacity, and low price. However, the poor cycling stability of manganese hexacyanoferrate, mainly caused by transition metal dissolution, side reaction, and phase transition, severely limits its practical application. In this study, gelatin is used to reduce the dissolution effect of transition metal manganese by limiting the content of free water in the electrolyte. Gelatin also improves the durability of the Zn anode. The optimized MnHCF/gel-0.3/Zn battery exhibits high reversible capacity (120 mAh center dot g(-1) at 0.1 A center dot g(-1)), excellent rate performance (42.7 mAh center dot g(-1) at 2 A center dot g(-1)), and good capacity retention (65% at 0.5 A center dot g(-1) after 1000 cycles).