In situ TEM visualization of single atom catalysis in solid-state Na–O₂ nanobatteries

Abstract

In situ TEM observation and DFT calculation provide an atomic-scale understanding of the electrocatalysis mechanism of single-atom catalysts in an Na–O2 nanobattery, where single-atomic Co sites facilitate the formation/decomposition of Na2O2.

All-Solid-State Na–O2 Batteries with Long Cycle Performance

“…41 The discharge cycle might be depicted as follows: when a negative potential is applied to the cathode, the Na + ions travel through the NZSP electrolyte, diffuse upon the CNT, and react with the electron and oxygen under Ru metal electrocatalysis to create Na 2 O 2 that rapidly covers the Ru/ CNT surface. 9 The reaction was reversible after the recharge, and the Na 2 O 2 peak disappeared. No Na 2 O 2 peak was visible for the pristine and recharged Ru/CNT cathode, indicating that the discharge product could be deformed, and the Ru/ CNT cathode could resume its initial stage.…”

“…In summary, ORR in the Ru/CNT cathode takes place when Ru metal is present. In the absence of Ru metal, no ORR takes place in the CNT cathode, and discharge is controlled by Na 2 O 2 and the intercalation of sodium ions and CNT . These outcomes suggest the superior electrocatalytic performance of the Ru/CNT cathode toward ORR and OER. ,,, Figure e,f displays discharge and charge voltage profiles of ASS Na–O 2 batteries with CNT and Ru/CNT cathodes at a current density of 100 mA g –1 and cutoff capacity of 500 mA h g –1 .…”

“…A sodium metal anode has long been recognized as a viable alternative to Li–metal anodes due to the plentiful availability of Na and the increasing cost of Li. − Na–O 2 batteries have a higher theoretical energy density of 1605 W h kg –1 , which is approximately six to nine times greater than that of Li-ion batteries. − Na–O 2 batteries are created by reacting Na with O 2 (2Na + O 2 → Na 2 O 2 ) to generate the discharge product Na 2 O 2 . , The Na 2 O 2 discharge products mainly contribute to oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Rechargeable Na–O 2 batteries require metal catalysts (such as Pt, Pd, Ru, Ir, Co, CuO, IrO 2 , and Co 3 O 4 ) that boost the performance and reversibility of ORR and OER. − Sun et al recently reported that Co/rGO cathodes are highly active for ORR and OER in NOBs (Na 2 O 2 as the discharge product). Furthermore, Kang et al and Jia et al found that Ru/carbon nanotube (CNT) and Co 3 O 4 /CNT cathodes play a crucial role in the OER and ORR for NOBs.…”

“…4−7 Na−O 2 batteries are created by reacting Na with O 2 (2Na + O 2 → Na 2 O 2 ) to generate the discharge product Na 2 O 2 . 8, 9 The Na 2 O 2 discharge products mainly contribute to oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Rechargeable Na−O 2 batteries require metal catalysts (such as Pt, Pd, Ru, Ir, Co, CuO, IrO 2 , and Co 3 O 4 ) that boost the performance and reversibility of ORR and OER.…”

“…Rechargeable Na−O 2 batteries require metal catalysts (such as Pt, Pd, Ru, Ir, Co, CuO, IrO 2 , and Co 3 O 4 ) that boost the performance and reversibility of ORR and OER. 9−14 Sun et al 9 recently reported that Co/rGO cathodes are highly active for ORR and OER in NOBs (Na 2 O 2 as the discharge product). Furthermore, Kang et al 13 and Jia et al 15 found that Ru/carbon nanotube (CNT) and Co 3 O 4 / CNT cathodes play a crucial role in the OER and ORR for NOBs.…”