Current Lithium ion batteries contain materials which are toxic and flammable. There is also a limit to the amount of energy they can store. Solid polymer electrolytes (SPEs) address the problem of safety and may allow us to create batteries with higher energy densities. However SPEs typically have low conductivities. To achieve higher values, confinement of the charge transfer on a nano- scale was used. This has previously been shown to be effective. Amorphous polyether was mixed with lithium salts and added to polycarbonate membranes containing nano- pores. A range of pore sizes were used to create solid polymer electrolytes with varying degrees of confinement. The impedance of the SPEs was tested as a function of temperature and pore size. We achieved conductivities comparable to small molecular systems in present lithium ion batteries. This is extremely promising for future high energy density battery applications, where long battery life and lightness are integral to improving performance.