Bottom-up synthesis of mesoporous germanium as anodes for lithium-ion batteries

A series of mesoporous germanium materials were synthesized via the self-templating method. Germanium tetrachloride and sodium potassium alloy were utilized as germanium precursor and reducing agent, respectively. The by-products, NaCl and KCl, could be considered as the in-situ templates. The characterization results showed that the mesopores could be obtained, when the salts were removed by water washing. Moreover, the crystalline germanium could also be achieved, when the calcination temperature is as high as 500 °C. However, when the calcination temperatures are 300 °C, the as-received mesoporous germanium materials are amorphous. When evaluated as anode for lithium-ion batteries (LIBs), the obtained mesoporous germanium exhibits outstanding cycling stability, showing a high reversible specific capacity of 803 mA h g^-1 after 100 cycles, as well as enhanced rate performance (655 mA h g^-1 at 1 C rate).