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

摘要

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 1000μA·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.