safe and stable li–co2 battery using conductive ionic liquid of 2-hydroxyethylammonium acetate as electrolyte and mwcnt composite cathode

As an emerging energy storage technology, the lithium-carbon dioxide battery has attracted worldwide attention in last decade, owing to its high theoretical specific energy density and recycling utilization of carbon dioxide from the atmosphere [1]. the involved electrochemical reaction in the li-co2 battery is 4li+ + 3co2 + 4e = 2li2co3 + c. until now, its development has been enormously hindered by the sluggish kinetics of carbon dioxide reduction and evolution reactions. during the discharging step, the co2 is reduced on the cathode and, the main challenge is the high charge potential that arises from the electro-inactivity of the discharge product, li2co3, largely constraining the electrochemical performance and recharge ability [2]. the high charge potential also induces the inevitable decomposition of the aprotic electrolyte, thus making li2co3 incompletely decomposed. this usually results in the low energy efficiency, poor cycling performance, and poor rate capability of existing li-co2 batteries. many efforts have been devoted to developing highly efficient catalysts, for which many carbons based materials and aprotic electrolytes are still the best choice for facilitating the li2co3 decomposition [3]. to achieve good rate capability, the catalysts should greatly enhance co2 reduction and li2co3 nucleation, furthermore the electrolyte must to be very cunductive . here, we demonstrates a li–co2 rechargeable battery with ionic liquid of 2-hydroxyethylammonium acetate ([2-hea][ac]) as electrolyte and multi-walled carbon nanotubes as cathodic material. the physicochemical properties of ionic liquid are evaluated using ftir and hnmr analysis. the ionic conductivity of the [2-hea][ac] is measured by electrochemical impedance spectroscopy and found to be ∼6.46 × 10−3 s.cm−1. further, the porous morphology of the carbon cathodes with mwcnts is examined by sem & tem techniques. the electrochemical performance of battery is evaluated by galvanostatic tests at a current density of 50 ma g−1 with a cut-off capacity of 500 mah g−1 for 180 cycles. the test results signify the high performance and good cyclic stability. the li–co2 cell has delivered a maximum capacity of 4988 mah g−1.