Atomic layer deposition-based synthesis of TiO2 and Al2O3 thin-film coatings on nanoparticle powders for sodium-ion batteries with enhanced cyclic stability

Abstract

Despite it being the leading technology for fabricating uniform-thickness metal and metal-oxide thin films on wafer-based substrates, atomic layer deposition (ALD) is yet to be utilized with powder-based substrates. Via the successful deposition of TiO2 and Al2O3 thin films on the surfaces of silica (SiO2) nanospheres, Prussian blue (PB) nanocubes, and NaTi2(PO4)3 (NTP) nanocubes using a home-built ALD system, this study demonstrates that ALD is a viable technique for depositing thin films on powdered substrates. Furthermore, amorphous TiO2 thin films are used as a protective layer to enhance the electrochemical properties of NTP nanocubes, which have application prospects in sodium-ion batteries. Whereas uncoated NTP nanocubes loses 67.9% of its initial charge capacity within 100 charge/discharge cycles, TiO2-coated (thickness: ~ 3 nm) NTP nanocubes reduces this capacity loss to 22.1%. This strongly suggests that powder-optimized ALD can be used to fabricate thin films for multiple applications that use powder-type nanoparticles, such as electrode materials and catalysts.