Researchers at Stanford University, with colleagues in Taiwan, have used an initially low surface area/porosity graphite (DGr) material as the positive electrode in a Li/Cl2 battery, attaining high battery performance after activation in CO2 at 1000 °C (DGr_ac) with the first discharge capacity ∼1910 mAh g–1 and a cycling capacity up to 1200 mAh g–1. The study is published in the Journal of the American Chemical Society.
In an earlier study, the researchers reported ∼3.5 V sodium/chlorine (Na/Cl2) and lithium/chlorine (Li/Cl2) batteries with up to 1200 mAh g–1 reversible capacity, using either a Na or a Li metal as the negative electrode, an amorphous carbon nanosphere (aCNS) as the positive electrode, and aluminum chloride (AlCl3) dissolved in thionyl chloride (SOCl2) with fluoride-based additives as the electrolyte.
The high surface area and large pore volume of aCNS in the positive electrode facilitated NaCl or LiCl deposition and trapping of Cl2 for reversible NaCl/Cl2 or LiCl/Cl2 redox reactions and battery discharge/charge cycling.
The new study found that the evolution of graphite over battery cycling, including intercalation/deintercalation and exfoliation, generated sufficient pores for hosting LiCl/Cl2 redox. This work could open up widely available, low-cost graphitic materials for high-capacity alkali metal/Cl2 batteries.