Preparation of SnO2-B2O3-P2O5 for the anode of Li-ion batteries by aerosol flame deposition(AFD)

Abstract

Tin oxide and amorphous tin borophosphate oxide have recently received significant attention as a possible new negative electrode material for lithium ion batteries. We employ a completely new method, called "Aerosol Flame Deposition (AFD)", to synthesize the amorphous tin oxide anode for a lithium ion secondary battery. In the deposition process, single or multicomponent amorphous oxide nano particles (soot) were synthesized by supplying metal halide sources such as chloride in the form of a gas into an oxy-hydrogen flame. The deposited soot composed of synthesized nano particles was subsequently consolidated by a high temperature heat treatment. The fine powder obtained was a mixture of crystalline tin oxide and an amorphous phase of B2O3 and P2O5, resulting in a highly dispersed structure with nano-scale interfaces. The mixture was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). According to the XRD results, the as-prepared materials seemed to have a semi-amorphous structure. However, SEM images showed that the tin-oxide was of a nano-crystalline structure with an average particle size of < 50 nm. The heat treatment improved the crystallinity of the tin oxide significantly. SEM images of the deposited surface after sintering revealed that the deposited soot was converted from a glass structure into amorphous borophosphate oxide and nano-crystalline tin oxide grains. The nano-structured SnO2-based electrode obtained exhibited improved capacity and cycling stability when tested in a conventional coin type cell.