Atmospheric Pressure Process for Coating Particles Using AtomicLayer Deposition

摘要

Atomic layer deposition (ALD) is a promising technique for coating micrometer- and nanometer-sized particles. Due to theself-terminating nature of the ALD half-reactions, the coating thickness can be controlled to the atomic level by choosing thenumber of cycles in which the half-reactions are repeated. This technique is performed in a fluidized bed reactor, underatmospheric pressure. LiMn_2O_4 particles (primary particles 200 -500nm in diameter) are coated with Al_2O_3 to variousthicknesses, ranging from 5 ALD cycles to 28 ALD cycles. The resulting coatings are homogeneous, and the individual particlesare coated, rather than the agglomerates as a whole; however there are indications of some build-up of water -mainly in poresthatmay be related to the use of atmospheric pressure. Quantitative characterization of the coating is difficult due to thepowdered substrate.