Graphene Modified with Glutarimide for Effective Immobilization of Polysulfides in High-Performance Li–S Batteries

Despite its high energy density, lithium–sulfur (Li–S) batteries are severely hampered by rapid capacity degradation due to “shuttle effect”. In this work, we introduce a polar organic molecule glutarimide (GIM) onto the nonpolar graphene (G) to form a G–GIM composite as host materials to accommodate sulfur and thus assemble the S/G–GIM cathode. First-principle calculations show that GIM can absorb on G via the charge-transfer effect among its N atom and C═O double bond, while the latter can effectively anchor the otherwise dissolved lithium polysulfides to bring them into closer contact with G. Such a configuration is also validated by experimental measurements. Electrochemical tests on the S/G–GIM cathode exhibit high discharge capacity, better rate performance, and longer cycling stability compared to the S/G cathode without GIM. Specifically, the S/G–GIM cathode exhibits an initial discharge capacity of 1327 mAh·gs–1 at a 0.2 C rate and 600 mAh·gs–1 after 500 cycles at a 1 C rate. Thus, the introduction of GIM in the sulfur cathode can effectively mitigate the “shuttle effect” and improve the utilization of active sulfur. The current study demonstrates that the polar organic molecule additives in carbon host as composite sulfur cathode provide an effective and feasible strategy for the high-energy-density Li–S batteries.