Particle size and multiphase effects on cycling stability using tin-based materials

The use of two tin-based powders of differing particle size oxidized to various extents at elevated temperatures allowed the quantification of the effect of a lithia (Li2O) matrix, resulting from the oxide conversion, on the material cycling efficiency. The lithiation capacity ratio of the 15th to the 2nd cycle was utilized as a measure of the material cycling efficiency. A linear variation was established for both types of materials between the capacity retention ratio and the first cycle irreversible capacity loss, which is directly correlated to the material oxygen content. An increase of the material oxygen content resulted in a systematic improvement of the material cycling stability. We also show that a decrease in particle size and a multiphase core at similar oxygen content further improves the material cycling stability. An alternative material exhibiting further improved electrochemical performance was also introduced.