CMK-3 modified separator for ultra-high stability performance Cu_(1.8)Se aluminum batteries

Rechargeable aluminum batteries(RABs)are a popular energy storage device because of its safety and environmental protection.As cathode materials of RABs,transition metal oxide,sulfide,and selenide have become the research hotspot.In this work,we have successfully prepared CuO,Cu_(1.8)S,and Cu_(1.8)Se electrode materials.Among them,although Cu_(1.8)Se had a relatively higher initial discharge capacity,all of these products had severe capacity degradation in terms of cycling and rate performance.Furthermore,for solving the problem of capacity decline,CMK-3 modified separator was used to make the Cu_(1.8)Se cathode material more stable,thus improving cycling and rate performance.It can be confirmed by ex situ X-ray photoelectron spectroscopy(XPS)that both Cu and Se elements underwent reversible redox reactions during the charging/discharging process.Density functional theory was implemented to study the energy storage mechanism of CumX(X=O,S,Se).The results showed that Cu_(1.8)S and Cu_(1.8)Se mainly relied on AlCl4−for energy storage,and the intercalation/de-intercalation of Al3+occurred during the charge/discharge process in CuO material.Consequently,the optimized Cu_(1.8)Se/CMK-3@GF/C/Al revealed an outstanding rate capability(977.83 mAh·g^(−1)at 0.5 A·g^(−1))and long cyclic stability(retention of 478.77 mAh·g^(−1)after 500 cycles at 1.0 A·g^(−1)).Compared to previously reported cathode materials of RABs,this type of battery displays great superiority in terms of rate and cycling stability.This research also provides a novel approach to suppress the shuttle effect of active species for advanced clean energy devices.