In-situ N-rGO Scaffold @3D Graphite Felt for High Power Polyhalide Hybrid Redox Flow Battery

Bromine polyhalide (BP) based redox flow batteries are considered as specific potential nominees for extreme energy level storage due to their high energy density as well as cost-effectiveness. However, the BP system encountered with slow kinetics of Br-2/Br- redox couple due to high positive electrode polarization results in poor power density. Herein, the heteroatom (nitrogen) doped reduced graphene oxide (N-rGO) composite electrode is designed and used as a positive electrode to improve the electro-catalytic activity of Br-2/Br- redox couple. The cellulose (Rayon) based graphite felt incorporated with N-rGO catalyst offers high conductivity and reduces the electrode polarization which in turn provides more catalytic sites for Br-2/Br- redox reaction. N-linked rGO preparation is carried out by two different methods namely, pyrolysis (thermally treated) and hydrothermally treated process called as HT-N-rGO@GF and Hy-N-rGO@GF, respectively. More impressively, the N-rGO adopted graphite felt (N-rGO@GF) exhibits remarkable rate performance even at 120 mA cm(-2). Moreover, no detectable degradation is observed for both N-rGO adopted felt over 100 cycles. The HT-N-rGO@GF and Hy-N-rGO@GF electrode shows 91.1% and 88.8% of Coulombic efficiency at 100th cycle respectively. On the other hand, the power density region of 1472 (HT-N-rGO@GF) and 1456 mW cm(-2) (Hy-N-rGO@GF) are observed, which seems to be much better than that of pristine felt (1275 mW cm(-2)).

Automated summary

Bromine polyhalide (BP) based redox flow batteries are potential candidates for extreme energy storage due to their high energy density and cost-effectiveness. However, the slow kinetics of the Br-2/Br- redox couple in the BP system leads to poor power density. To address this issue, a nitrogen-doped reduced graphene oxide (N-rGO) composite electrode is designed and used as a positive electrode to improve the electro-catalytic activity. The N-rGO adopted graphite felt exhibits excellent rate performance and Coulombic efficiency, as well as higher power density compared to the pristine felt.