A dibutylhydroquinone/dibutylbenzoquinone-Cd2+/Cd self-stratified Battery

Self-stratified battery is a new type of rechargeable battery potentially applicable for large-scale energy storage. It has a thermodynamically stable membrane-free self-stratified architecture which endows the battery with low cost, high cycling stability and excellent safety. In this paper, a novel self-stratified battery based on quinone cathode is reported. 2,5-di-tert-butyl-1,4-hydroquinone (DBHQ) is studied as the reversible redox active material at the cathode side. It is dissolved in an organic solvent to form the catholyte which is immiscible with the aqueous electrolyte. The aqueous electrolyte is composed of sulfuric acid/magnesium sulfate/ cadmium sulfate mixed aqueous solution. Cadmium metal is used as the anode material. Due to density difference, the organic catholyte, aqueous electrolyte and cadmium metal anode are automatically stratified and forms a thermodynamically stable cell structure. The charge/discharge process of the battery is accompanied with the migration of proton between the organic and aqueous phases. Interestingly, we found that adding bis trifluoromethyl sulfonimide anion (TFSI-) in the organic phase would effectively reduce the battery polarization and improve the cycle performance. Through spectroscopic analysis, we ascribe such performance improvement to the increase of proton concentration in the organic layer and the solvation structure change of DBHQ molecules. Our work extends the active materials system of self-stratified cells to quinone compounds and demonstrates novel performance influencing mechanism based on catholyte solvation structure.

Automated summary

Self-stratified battery, a new type of rechargeable battery, has shown great potential for large-scale energy storage. It possesses a thermodynamically stable membrane-free self-stratified architecture, resulting in low cost, high cycling stability, and excellent safety.