A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries

Abstract

Due to the high theoretical specific energy, the lithium–oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge–charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life (> 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air.

Electrolytes for Rechargeable Lithium–Air Batteries

“…Mixed solvents combine the merits of different solvents and sometimes display synergistic effects. A large number of combinations are possible given the enormous number of aprotic solvents and RTILs . In addition, the concentrations of Li salts and additives related to the formation of stable SEI layers require further optimization .…”

Safe Lithium‐Metal Anodes for Li−O2 Batteries: From Fundamental Chemistry to Advanced Characterization and Effective Protection

“…Wang et al. reported the severe corrosion and dendrite formation problems of Li‐metal anode in Li−O 2 batteries by SEM and proposed a multifunctional ionic liquid electrolyte to overcome these problems . Zhang et al.…”

Critical Advances in Ambient Air Operation of Nonaqueous Rechargeable Li–Air Batteries

“…Unlike most other batteries that must incorporate both the anode and cathode are incorporated inside the storage system, the cathode material (oxygen) of the nonaqueous Li-air batteries is not stored in the battery. [15][16][17][18][19] Instead, oxygen is from the air environment and reduced by catalytic sites inside the air cathode. [20] During discharge in the cathode, O2 is reduced to form Li2O2, while the latter is oxidized to release O2 on charge.…”