Polysaccharide Modified Cathodes for High-Capacity Rechargeable Nonaqueous Li-O₂ Batteries

Nonaqueous rechargeable Li-O₂ 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, Li₂O₂, 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 pK_a) at the cathode helps to stabilize the intermediate, LiO₂, via an energetically favorable pathway and delays the precipitation to Li₂O₂, without any parasitic reaction, unlike the other reported low pK_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-O₂ batteries.