Dual Protection Strategy by Constructing MXene-Coated Cu2Se-Cu1.8Se Heterojunction and CMK-3 Modification for High-Performance Aluminum-Ion Batteries.

The fabrication of cathode materials with ideal kinetic behavior is important to improve the electrochemical performance of aluminum-ion batteries (AIBs). Transition metal selenides have the advantages of abundant reserves and high discharge specific capacity and discharge voltage plateau, which makes them a promising material for rechargeable AIBs. It is well-known that the low structural stability and relatively poor reaction kinetics pose a considerable challenge to the development of AIBs. The cubic structure of Cu2Se-Cu1.8Se can adapt to the volume change of the active material during cycling and facilitate the intercalation and deintercalation of chloroaluminate anions in the cathode material. We created a two-fold protection mechanism for AIBs with a CMK-3 modified separator and a Cu2Se-Cu1.8Se heterojunction coated with MXene in order to better mitigate the detrimental impacts. In addition to offering numerous electronic transmission routes, MXene and CMK-3 help prevent the solubilization of active species. This novel design enables the Cu2Se-Cu1.8Se@MXene composite to have a high initial discharge capacity of 705.5 mAh g-1 at 1.0 A g-1. Even after 1500 cycles at 2.0 A g-1, the capacity is still maintained at 225.1 mAh g-1. Furthermore, the reaction mechanism of AlCl4- intercalated/deintercalated into Cu2Se-Cu1.8Se heterojunction is revealed during charge/discharge. This work to construct novel cathode materials has greatly improved the electrochemical performance of AIBs.

Metal-Organic Framework Structure with Fe-Co-Se (MIL-88A/Fe-Co@Se) as a Cathode for Aluminum Batteries.

Rechargeable aluminum-ion batteries have received more and more attention because of their high theoretical energy density, high safety, and reasonable price. The cathode material of aluminum batteries is one of the key bottlenecks that limits their development. Although there are many reports on aluminum battery cathode materials, many of these reports fail to simultaneously solve the poor cycling stability and low specific capacity of aluminum batteries. Therefore, we formed YSNT@Se hybrids by compounding the MOFs─MIL-88A@Fe-Co hydroxide yolk-shell nanotubes (YSNTs) with selenium for the first time. It was finally determined that the FeSe2 in YSNT@Se is the main redox reaction participant during charging/discharging. In the charge/discharge of YSNT@Se 500 °C, it achieved a first cycle discharge specific capacity of 292.21 mA h g-1. After 500 cycles, the discharge capacity was 233.34 mA h g-1 and the capacity retention rate reached 79.85%. This result proves that the redox process is highly reversible at the same time. This work makes it possible for aluminum batteries to have a high cycling performance and a high capacity and broadens the research direction of cathode materials for aluminum batteries.