Investigation of stable structures of known and new ion conducting crystals

A solid electrolyte known as LiPON, was developed at Oak Ridge National Laboratory is currently used in microbatteries. At Wake Forest University, we have been studying computer models of related crystals which are composed of mobile Li ions in a framework composed of phosphorus, oxygen, and nitrogen. For example from the known structure of LiPO₃ (shown in the left diagram below), we asked the question “what would happen if we could replace some of the oxygen atoms with nitrogen?”. We found that the complicated chain structure of LiPO₃ changed into a much simplier structure shown on the right diagram below. This Li₂PO₂N has not yet been physically realized. The computer modeling group of N. Holzwarth is currently working with the experimental groups of R. Williams and A. Lachgar to synthesize this interesting model material.