Lithium ion batteries are now deployed to various portable electric devices and electric vehicles. However, the energy density, especially the volumetric energy density of the battery does not reach ideal target from a consumer perspective. The multivalent metal batteries are one of the promising candidates as a beyond lithium ion battery with 2–3 times the energy density of what lithium ion can offer.

Among multivalent metals, magnesium provides double the volumetric capacity of lithium. However, the standard reduction potential of magnesium is 700 mV less negative than that of lithium. Therefore, the approach to increasing its operating voltage is very important to increase energy density of battery.

Due to the demand for high voltage operation, comprehensive efforts have been demonstrated for high voltage electrolyte. The oxidative stability of many magnesium electrolytes is reported to be over 3 V vs Mg when tested by cyclic voltammetry on a Pt working electrode. However, their window of operation when assembled in coin cells and operated at constant current using typical stainless steel current collector and case is rarely above 2.0 V.

We demonstrated assembly of pouch cells for multivalent metal batteries and performed electrochemical testing. Initial work to identify high-performing materials, composition, fabrication variables and cycling conditions is conducted in cyclic voltammetry and coin cell test. The resulting information is then used for the pouch cell demonstration.