Batteries have a variety of applications, including as storage of energy generated from renewable sources such as wind and solar. Whilst lithium-ion batteries dominate the portable electronics markets, sodium-ion batteries can be seen as contenders for static energy storage in the grid. For grid storage applications, the lower cost of sodium compared to lithium is much more important than the additional weight. To date, layered materials exhibit the best performance as positive electrodes in sodium ion batteries. Our recent work shows excellent cycling from the P3 structure. The aim of this experiment is to carry out detailed crystallographic studies on a number of samples post battery testing. In turn the detailed structural models will enhance our understanding of our electrochemical data.