Converting waste CO2 back into valuable liquid fuels or chemicals, with renewable electricity as the energy input, can revolutionize the way we produce chemical feedstocks while mitigating climate change. In traditional electrochemical CO2 reduction reactors generated liquid fuels are inevitably mixed with impurity ions (such as potassium, bicarbonate, etc.) in liquid electrolytes, which necessities energy- and cost-intensive downstream separation processes. This long-standing impurity challenge also significantly limits the applications of other electrosynthesis systems beyond CO2 reduction. We propose a game-changing solid electrolyte reactor design, by separating the cathode and anode with a porous solid electrolyte layer, to enable a continuous and direct generation of pure liquid fuels from CO2 without any impurity ions involved. This solid electrolyte reactor design will also serve as a platform to stimulate new fundamentals in electrochemistry.