Zinc Chrome Battery

The electrochemical characteristics of oxidization and reduction of Cr³⁺ in Cr⁶⁺/Cr³⁺ which was used as one pole-reaction in zinc-bichromate batteries were studied in this work. The influences of the concentrations of H₂SO₄ and Cr₂(SO₄)₃ as well as the kind and content of other additives were included. On the other hand, zinc-bichromate batteries was made, and the discharge characteristics of the Zn-(NH₄)₂Cr₂O₇ and Zn-Na₂Cr₂O₇ batteries were also investigated, including the calculation of the actual gravimetric energy density of Zn-(NH₄)₂Cr₂O₇ battery.When the concentrations of H₂SO₄ and Cr₂(SO₄)₃ were increased, the discharge performance of oxidization and reduction of Cr(â…¢) was improved. The best electrochemical characteristics were obtained when the concentration of H₂SO₄ and Cr₂(SO₄)₃ was 1.34 and 0.08 mol/L, respectively. When SDS was added into the mixture of Cr₂(SO₄)₃ and H₂SO₄, the electrochemical characteristic of Cr(â…¢) was improved obviously and the current of the oxidization of Cr³⁺â†'Cr⁶⁺ increased approximately 80 mV compared to that didn't include SDS, and its reversibility was also improved.Zinc-bichromate batteries were made with soluble oxidants- bichromateas an active cathode substance in the cathode zone, and active metal-zinc pieces being used as an anode . Ammonium chloride was used as an electrolyte in an anode zone, with acids and carbon felt as an inert cathode in zinc-bichromate batteries. There were 50 ml of solution in both the anode and cathode zones, with a PE-01 homogeneous membrane used as the membrane between them. The discharge characteristics of the batteries were investigated at 5 ohms. The experimental results showed that their output voltages commonly exceeded 1.70 V at the beginning of discharge and discharge time was more than 10 hours. The discharge characteristics of zinc-bichromate batteries were improved when the concentrations of acid increased. But, when the aicdity was too high, the results become bad. The mixed acid was better than single one. When the concentration of bichromate, H₂SO₄ and HC1 in the cathode zone was 0.75, 1.8 and 4.8 mol/L, respectively, and the concentration of NH₄Cl in the anode zone was 5 mol/L, zinc-bichromate batteries reaveled better discharge characteristics. Under such conditions, the actual gravimetric energy density of the Zn-(NH₄)₂Cr₂O₇ battery arrived at 51.93 W·h·kg^-1.