The effect of nitrogen on the cycling performance in thin-film Si1−xNx anode

The effects of nitrogen on the electrochemical properties of silicon–nitrogen (Si1−xNx) thin films were examined in terms of their initial capacities and cycling properties. In particular, Si0.76N0.24 thin films showed negligible initial capacity but an abrupt capacity increase to ∼2300 mA h/g after ∼650 cycles. The capacity of pure Si thin films was deteriorated to ∼20% of the initial level after 200 cycles between 0.02 and 1.2 V at 0.5 C (1 C=4200 mA/g), whereas the Si0.76N0.24 thin films exhibited excellent cycle-life performance after ∼650 cycles. In addition, the Si0.76N0.24 thin films at 50 °C showed an abrupt capacity increase at an earlier stage of only ∼30 cycles. The abnormal electrochemical behaviors in the Si0.76N0.24 thin films were demonstrated to be correlated with the formation of Li3N and Si3N4.