Research interest on zinc (Zn)-anode aqueous-based batteries have renewed recently because of its low equilibrium potential in aqueous electrolyte, low cost, non-toxic and nonflammable characteristics compared to lithium-ion batteries. Zn has a high theoretical capacity of 820mAh/g based on two electron reactions, thus it has the capacity to deliver high energy density if it is paired with an equally high capacity cathode. Silver and nickel are high capacity cathodes; however, they are very expensive and require the addition of expensive additives like cobalt in nickel to increase the rate of the battery. MnO₂ is the best cathode to be paired with Zn because it has a high two electron capacity of 617mAh/g and it is extremely safe and economical. Recently, we showed that attaining the two electron capacity of 617mAh/g for over 3000 cycles was possible with the used of bismuth and copper additives. Energy densities >160Wh/L were attainable when the cathodes were paired with Zn at 15% utilization.^1-4 However, they are still susceptible to Zn poisoning which lead to the formation of inactive phase called haeterolite (ZnMn₂O₄). To improve the energy densities of Zn-anode batteries new inexpensive and safe cathodes with higher capacity than MnO₂ and increasing Zn utilizations to >20-25% are a must.

In this presentation, we will report the synthesis of a new Mn-based cathode that delivers capacity ~800mAh/g, which is almost comparable to the Zn anode theoretical capacity. This new Mn-based cathode is able to deliver its capacity at high rates and maintain its capacity at high cycle life. We will present the reaction mechanism of this Mn-based cathode through real time microscopy videos and images, high resolution transmission microscopy and electroanalytical methods. We also report on the use of new Zn-based anodes that utilize >20% of its theoretical capacity and, at the time of this writing, still cycle with much deterioration in capacity due to shape change or passivation. The combination of the new high capacity Mn-based cathode and high utilization Zn-based anode results in a cell that delivers energy density >200Wh/L.

Funding:

This work was supported by the New York State Research and Development Authority (NYSERDA) under Project Number 58068.

References:

1] Yadav, G. G.; Gallaway, J. W.; Turney, D. E.; Nyce, M.; Huang, J.; Wei, X.; Banerjee, S., Nat. Commun., 2017, 8, 14424

2] Yadav, G. G.; Wei, X.; Huang, J.; Gallaway, J. W.; Turney, D. E.; Nyce, M.; Secor, J.; Banerjee, S., J. Mater. Chem. A, 2017, 5 (30), 15845-15854

3] Yadav, G. G.; Wei, X.; Gallaway, J. W.; Chaudhry, Z.; Shin, A.; Huang, J.; Yakobov, R.; Nyce, M.; Vanderklaauw, N.; Banerjee, S. Materials Today Energy, 2017, 6, 198-210.

4] Yadav, G. G.; Wei, X.; Huang, J.; Turney, D.; Nyce, M.; Banerjee, S. International Journal of Hydrogen Energy, 2018, https://doi.org/10.1016/j.ijhydene.2018.03.061