KSEF RDE: Safe, Low-cost High Energy Density Dual Ion Battery

The objective is to demonstrate and validate a low-cost, secondary Na/Zn battery having a zinc anode, a sodium-ion intercalation cathode and a liquid electrolyte featuring both sodium and zinc salts dissolved in a suitable organic solvent. The positive electrode is an intercalation cathode capable of reversibly inserting and extracting Na ions. The active material for the positive electrode is based on low-cost MnO2 having the appropriate phase purity and structural framework to achieve the desired tunnel size and structure to accommodate reversible intercalation of Na ions. The negative electrode operates by simply stripping and plating zinc metal. Rechargeable battery systems based on multivalent cations provide potential advantages over monovalent cation-based chemistries such as lithium-ion. Advantages include increased energy density, leading to potentially lighter battery systems (i.e. more charge carriers per unit mass) that can employ metal anodes with high energy density, including aluminum, magnesium, or zinc, leading to higher voltage systems. The proposed battery chemistry has a nominal operating voltage of ca. 2.4 V and calculated energy density of ca. 320 Wh/kg (based on active materials only). For comparison, Li-ion has an energy density of ca. 370 Wh/kg (based on active materials only). The projected battery chemistry is expected to have a practical energy density exceeding 75 Wh/kg, equivalent to most secondary commercial batteries used currently. The battery system will be inherently safe, scalable, and capable of excellent power performance. Projected market applications for the proposed battery include portable power (cellular phones, laptop computers and tablets), stationary power (large scale electric utility grid storage and uninterruptable power supplies) and electric vehicles (starting, lighting and ignition).