Rational design of integrative CNTs@Ge nanotube films as binder-free electrodes for potassium storage

Alloying materials hold great potential as the anodes for potassium-ion batteries (KIBs). However, the large volume changes during K+ alloying/dealloying reactions can lead to structural damage of the electrodes, resulting in fast capacity loss and shortened cycle life. Herein, we report the design of integrative carbon nanotubes@germanium (CNTs@Ge) films on copper foil by combined chemical and physical vapor deposition. Electrochemical tests show that the integrative CNTs@Ge films, working as binder-free electrodes, demonstrate higher specific capacity and rate performance in comparison with pristine Ge and CNTs electrodes. In addition, the CNTs@Ge films also deliver a long cycling stability with an areal specific capacity of 0.0417 mAh.cm(-2) after 450 cycles at 1000 mu A.cm(-2). The enhanced potassium storage properties can be attributed to the interweaved CNTs with abundant space that can effectively buffer the volume expansion of Ge during alloying/dealloying process.

Automated summary

The study reports the design of integrative carbon nanotubes@germanium films as binder-free electrodes for potassium-ion batteries. The films demonstrate higher specific capacity, rate performance, and cycling stability compared to pristine germanium and carbon nanotubes electrodes. The enhanced potassium storage properties are attributed to the interconnected carbon nanotubes that effectively buffer the volume expansion of germanium during alloying/dealloying process.