Lithium silicon tin oxynitride (LiySiTON): high-performance anode in thin-film lithium-ion batteries for microelectronics

A lithium-ion thin-film battery, consisting of the amorphous silicon tin oxynitride anode (‘SiTONʹ), the amorphous lithium phosphorus oxynitride electrolyte (‘Liponʹ), and a crystalline LiCoO2 cathode, can be heated at 250°C in air for 1 h which exceeds by far the required solder reflow conditions for electronic circuit assembly. Moreover, the performance of such a battery was found to even improve after the heat treatment. The LiySiTON profile between 0 and 1.2 V vs. Li was determined in SiTON/Lipon/LiCoO2 lithium-ion thin-film cells equipped with a Li metal reference electrode. By comparison with a Sn3N4/Lipon/LiCoO2 three-electrode lithium-ion thin-film cell, a model for the electrochemical insertion/extraction process of LiySiTON was suggested. The SiTON/Lipon/LiCoO2 cells sustained 5 mA/cm2 between 4.2 and 2.7 V while the anode supplied a reversible discharge capacity of about 340 μA h/mg or even 450 μA h/mg after heating at 250°C in air for 1 h. A long-term cycling stability test of a SiTON/Lipon/LiCoO2 battery between 3.93 and 2.7 V demonstrated that the LiySiTON capacity faded only by 0.001% per cycle when charging was stopped as soon as the LiySiTON potential reached 0 V vs. Li. When this cathode-heavy cell was charged to 4.1 V (LiySiTON at 0 V vs. Li), a significantly higher reversible discharge capacity was obtained over not, vert, similar5000 cycles.