Polysaccharide Modified Cathodes for High-Capacity Rechargeable Nonaqueous Li-O 2 Batteries.

Nonaqueous rechargeable Li-O 2 batteries are recognized as possible alternatives to the currently established Li-ion battery technology for next-generation traction by virtue of their high specific energy. However, the technology is still far from commercial realization mainly due to the performance-limiting reactions at the cathode. The insulating discharge product, Li 2 O 2 , can passivate the cathode leading to issues such as low specific capacity and early cell death. Herein, the -OH functionalities at the cathode, incorporated by polysaccharide addition, are shown to enhance the discharge capacity and cyclability. The -OH functional group (high p K a ) at the cathode helps to stabilize the intermediate, LiO 2 , via an energetically favorable pathway and delays the precipitation to Li 2 O 2 , without any parasitic reaction, unlike the other reported low p K a additives. The role of the functionalities is studied using various experimental techniques and first principles density functional theory based studies. This approach provides a rational design route for the cathodes that provide high capacities for the emergent Li-O 2 batteries.