Electrolyte additive optimizing anode interface and suppressing dendrite formation for long-cycled rechargeable aluminum batteries

Aluminum (Al) metal is a promising anode material for rechargeable aluminum batteries (RABs) due to its high abundance and specific capacity. However, its application is limited by dendrite formation and ultra-thick separators are usually required. Here, we propose that silica nanoparticles (nano-SiO₂) can serve as multifunctional additive for chloroaluminate electrolyte (IL) because of their unique physicochemical properties. By combining experimental and simulation studies, nano-SiO₂ form a colloidal system with IL, which helps nano-SiO₂ play a positive role throughout battery lifecycle. They help to uniform electric field, increase ion migration number and promote electrochemical reactions on the anode side, which inhibits the growth of Al dendrite and enhances the cycle life of battery. By using IL-SiO₂-3‰, the cycle life of the symmetric cell increases to 2,300 h at 1 mA cm⁻², which is approximately 80 times greater than that using IL. The cycle number of the Al//graphite full battery increases from 3644 in IL to over 26,000 in IL-SiO₂-3‰ at 2 A g⁻¹ with a capacity retention of ~99%. This work provides a valuable direction for the further optimization of the interface between metal anode and electrolyte in rechargeable batteries.