The binder-free Ca2Ge7O16 nanosheet/carbon nanotube composite as a high-capacity anode for Li-ion batteries with long cycling life

Abstract

We report a facile one-step route to synthesize a Ca₂Ge₇O₁₆ nanosheet (NS)/carbon nanotube (CNT) anode for the first time. The Ca₂Ge₇O₁₆ NS/CNT composites are uniformly grown on the surface of three-dimensional Ni foam used as the conductive current collector. The Ca₂Ge₇O₁₆ NS/CNT composite is used as a binder-free anode for lithium-ion batteries, which delivers a reversible capacity of 998.5 mA h g⁻¹ at a current rate of 0.5 A g⁻¹ and exhibits excellent cycle performance (87% retention of its 2nd cycle reversible capacity after 1000 cycles). Furthermore, a binder free full cell is fabricated, which shows excellent cycle performance with 96% retention of its 10th cycle capacity after 100 cycles. The superior cycling performance is attributed to the synergetic effect of small diffusion lengths in NS, sufficient void space to buffer the volume expansion, the CNT for charge transport and a continuous 3D electronic path of the Ni foam.