A hybrid electrolyte energy storage device with high energy and long life using lithium anode and MnO2 nanoflake cathode

• Hybrid electrolyte device based on MnO2 nanoflakes supercapacitors and lithium batteries
• The specific energy for the cathode materials is 170 Wh kg− 1.
• More than 85% retention up to 2400 cycles
• A great candidate for stationary batteries

A hybrid electrolyte energy storage system combining the features of supercapacitors and lithium batteries has been constructed. It consists of MnO2 nanoflakes in 1 M Li2SO4 aqueous electrolyte as the cathode and lithium foil in ionic liquid (1 M lithium bis(trifluoromethanesulfonyl)imide (LiNTf2) in N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide ([C3mpyr][NTf2])) electrolyte as the anode, separated by a lithium super ionic conductor glass ceramic film (LiSICON). This system shows the advantages of both a supercapacitor (long cycle life) and a lithium battery (high energy), as well as low cost and improved safety due to the combination of ionic liquid and ceramic solid state electrolyte in lithium side, which can reduce the formation and prevent the penetration of lithium dendrites. The specific energy for the cathode materials in the hybrid electrolyte system is 170 Wh kg− 1 with more than 85% retention up to 2400 cycles. This system is a great candidate for stationary batteries storing solar and wind energy.