Encapsulation of alloy heterojunctions in N/P-doped carbon nano-armor for ultra-long-life rechargeable/flexible zinc-air batteries

Rechargeable/flexible zinc-air batteries (ZABs) show great potential for energy storage, yet cathode catalysts currently used lack durability under harsh conditions. Thus, rational catalyst design and the protection of the primary active site in these environments are critical. Here, we have developed an innovative catalyst by encapsulating the Co/Co 3 Fe 7 alloy heterojunction within a N, P co-doped multifunctional carbon nano-armor (Co/Co 3 Fe 7 @PNCNT), employing both armor protection and heterojunction engineering strategies. The formation of the Co/Co 3 Fe 7 heterojunction can adjust the d-band center and induce a local electric field effect to promote ORR (oxygen reduction reaction)/OER (oxygen evolution reaction) activity. The tubular carbon nano-armor effectively prevents metal particle aggregation, corrosion, and ensures long-term stability in strongly alkaline environments. Co-P bonds construct atomic-level electron transfer channels between the metal heterojunction as well as the nano-armor, accelerating charge transfer to promote ORR/OER reaction kinetics. Density functional theory calculations also confirm the construction of an internal electric field at the Co/Co 3 Fe 7 interface and the adjustment of the d-band center via the heterojunction formation. The Co/Co 3 Fe 7 @PNCNT-based rechargeable/flexible ZABs has excellent power density and ultra-long-term cycling stability (1730 h). It exhibits great potential in large-scale energy storage, portable electronics and wearable devices. This work provides a new design route for the precise construction of multifunctional nano-armor and heterojunctions.