Multivalent batteries based on Mg2+, Al3+, Ca2+, or Zn2+ may have advantages over traditional lithium ion batteries, particularly in the area of volumetric capacity. Each of these chemistries, however, presents challeges which inhibit implementation. In this talk we discuss aspects of each chemistry. With regard to Mg and Ca, we discuss the essential features of electrolytes that support reversible cation depositon and stripping. The crucial feature is the presence of electrolyte components whcih depassivate the electrode. In the case of Mg, this depassivation is typcially provided by Cl-. In the case of Ca, depassivation comes from hydride fromation at the interface. In both cases, the necessisty to form a depassivation product leads to altered deposition kinetics. For Al and Zn we disucss cathodes. For Al, we report a new C3N4-based cathode, and on the mechanism of Al interaction with it. In particular, Al associates with C3N4 not as bare Al3+, but rather as a AlCl4-. For Zn, we report a new series of spinels -- ZnAlxCo2-xO4 and ZnNixMnxCo2-2xO4 -- and discuss their utility as cathode materials for non-aqueous Zn-ion battery. The data show that the Zn2+ ions reversibly intercalate into the spinel structure during the charge/discharge processes, a compositional transformation directly correlated with a multiply reversible conversion between Co4+/Co3+ or Co4+/Co3+, Ni4+/Ni3+/Ni2+ and Mn4+/Mn3+ oxidation states within the lattice. The data suggest that Mn, Ni co-substitution for Co in ZnCo2O4 is an efficient method to facilitate Zn-deintercalation and enhance discharge capacity.

Multivalent battery chemistries: Anodes, cathodes, and electrolytes

2019 Fall National Meeting

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