Tailoring nanoporous structures of Ge anodes for stable potassium-ion batteries

We present here for the first time the electrochemical behavior of germanium anodes in potassium-ion batteries (KIBs). Nanoporous germanium (np-Ge) samples were fabricated by the chemical-dealloying method using Al as the sacrificial metal. Galvanostatic tests identified the reversible potassiation of the np-Ge anodes and the optimal sample with tuned porosities and ligaments demonstrated stable capacities of similar to 120 mAh g(-1) over 400 cycles. Further analysis of the np-Ge electrode revealed amorphous K-Ge alloys were formed upon discharge. This study suggest germanium can be a potential anode in KIBs, but the structural tailoring is critical to overcome the kinetics problems of the large K-ions.