As conversion electrodes in lithium ion batteries, Sn and SnO₂ have been well studied in the literature, while the properties of Sn₃N₄ and SnO_xN_y have yet to be been explored in any detail. To study the differences in the electrochemical performance of SnO_2, Sn₃N_4, and SnO_xN_y, an ALD process was developed which allows for a controlled N/O ratio. This process uses tetrakis(dimethylamido)tin (TDMAS) as a precursor with remote nitrogen plasma and H₂O. As with many nitride ALD processes, obtaining Sn₃N₄ films with low O and C contamination is challenging due to the greater reactivity of Sn with O, and incorporation of precursor ligands. Optimized process parameters for the pulse times and substrate temperature were obtained for the nitride process, which were incorporated into the oxynitride process. SnO_xN_y films were grown by periodically pulsing water into the reactor after several cycles of the nitride process. By varying the number of nitride cycles between water pulses, the relative concentration of O and N in the film can be controlled between 0% N and 95% N.

The Li₂O matrix formed on conversion of SnO₂ is expected to be more chemically stable than the Li₃N matrix formed from Sn₃N₄, but at the cost of lower ionic conductivity. Solid-state half cells were constructed using SnO_2, Sn₃N_4, and SnO_xN_y thin films versus thermally evaporated Li with ALD LiPON as the electrolyte. The electrochemical properties of the anodes were tested by cyclic voltammetry and galvanostatic cycling. Only a single narrow conversion reaction was observed, regardless of film composition, but the voltage at which the reaction occurred shifted as a function of the N/O ratio. At voltages below 0.4 V vs Li/Li⁺ the half cells shorted, possibly due to mechanical breakdown of the LiPON layer from significant volume expansion of the anodes during the alloying reaction with Li. However, the stability of the cells was improved by varying the composition and thickness of the anodes. Galvanostatic intermittent titration and impedance spectroscopy were used to analyze the ionic conductivity of the anodes before and after the initial conversion reaction and as the N/O ratio was varied. The high energy storage capacity of SnO_xN_y electrodes, which can be deposited conformally by ALD, makes them attractive materials for applications in thin film, solid state devices, where the particle aggregation and delamination effects are limited by the physical constraints of the device.