The Mystery and Promise of Multivalent Metal-ion Batteries

Volumetric energy density estimates and projections for MV-ion metal battery systems as a function of the metal anode utilization (%). The dashed lines and circles denote estimated values for current MV-ion systems with a V2O5 cathode. The solid lines and stars display projections for a novel cathode material with higher average operation voltage or specific capacity, both of which could decrease the cathode/anode thickness ratio to 1/3 of that used for V2O5 calculation.

Scientific Achievement

In this perspective, we highlight some of the recent progress and uncertainty in elucidating capacity contributions and accompanying mechanisms for different charge carriers. We then discuss cell balancing and increasing metal anode utilization as major remaining challenges, and propose design strategies and future directions for realizing practical MV metal-ion batteries.

Significance and Impact

Establishing realistic performance expectations for multivalent metal-ion battery chemistries at the electrode and full cell levels remains an intensely debated topic in the field. This perspective provides insight into some of this ambiguity and design strategies toward realizing practical MV-ion batteries that can complement or eclipse existing Li-ion battery systems for particular applications.

Research Details

  • Discussion of possible charge carriers in MV-ion batteries (H+, MV-ion, structural ion, anion, and charged solvates/complexes) and a highlight of current and future characterization needed to distinguish contributions
  • A direct link is drawn between energy density and increasing metal anode utilization, which places emphasis on the development of more efficient electrolytes for MV-metal (Zn, Mg, Al, etc.) anodes.
  • Development of positive electrode materials with higher capacities and operating voltages will be necessary from a cell engineering perspective to achieve practical performance metrics.

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DOI: 10.1016/j.coelec.2021.100819

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