Here we propose to use muon spectroscopy to study the diffusion of sodium in hard carbon anode materials of various porosity for sodium ion batteries. Hard carbon is the most promising candidate for anode material in sodium ion batteries, but it needs to be improved in order to become a viable alternative to lithium ion batteries. The main benefit of the sodium ion batteries is the low cost and hence any improvement should add more expenses to the components of the battery, therefor we here plan to understand how simple changes( in this case porosity) can improve the diffusion of sodium to increase the capacity and charge rate of hard carbon anode materials.