High Performance Zinc Ion Battery Achieved By Tuning The Electrolyte

The purpose of exploiting energy storage systems with high energy density has been promoting the research on electrochemically reversible redox couples that embrace multi-electron transfer at a higher potential.Moreover,concern about the cost and safety issues has lead us to searching for novel energy devices beyond LIBs.Recently,as a sort of batteries utilizing zinc anode,great focus has been put on zinc ion battery due to its cost-effectiveness,environmental friendliness and aqueous compatibility.Up to now,Various kinds of cathode materials based on Zn²⁺intercalation/de-intercalation have received extensive study.Nevertheless,the destruction of cathode structure along with high resistance of Zn²⁺during de/intercalation process restricts the further enhancement of battery performance.with that aspect,the metal-halide batteries with high capacity and fast kinetic conversion of halide reaction have got the interest,while still lacking of the ability to take full advantages of high energy density on zinc anode side.Herein,we put forward a novel zinc-iodine battery based on the I₂/I⁺conversion.By electrolyte manipulation and introducing I⁺stabilizer to suppress the hydrolysis of I⁺,a four electrons transfer reaction was achieved.Experiment characterization and MD simulation on electrolytes structure have revealed that limited water activity and sufficient Cl^-played a vital role in activating and stabilizing the conversion from I₂ to I⁺.Such electrolyte（called‘Acetonitrile/Water in Bisalts’）can also function as suppressing the dendrite on zinc anode.Therefore,the specific capacity as high as594m Ah g^-1 along with the energy density of 750 Wh kg^-1 were achieved benefited by its higher operation voltage.A long cycle performance above 6000 cycles was also striking.Besides,we also investigated the anion-type graphite intercalation reaction due to the high redox potential it can provide.A zinc dual ion battery configuration was invented here and by electrochemical analysis and XRD characterization,we have proved the de/intercalation process of anion both in organic and in aqueous solution,which provided a high discharge voltage at 2.3 V and 2.1 V,respectively.Take into consideration the low cost for both cathode and anode,such zinc dual ion battery has promising application.