Crumpled N-Doped Carbon Nanotubes Encapsulated with Peapod-Like Ge Nanoparticles for High-Rate and Long-Life Li-ion Battery Anodes

Germanium (Ge) is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical specific capacity of 1620 mA h g−1. However, the large volume change during Li alloying/dealloying causes cracking and pulverization of the Ge anodes leading to rapid fading of the capacity. Herein, we report a novel peapod-like Ge/N-doped carbon (Ge/CNx) as a high-performance anode material for LIBs, in which isolated Ge nanoparticles are incorporated into crumpled CNx nanotubes. The peapod-like Ge/CNx not only provides enough voids to accommodate the volume expansion of pea-like Ge NPs during the Li–Ge alloy reactions, but also offers a continuous conducting framework for electron transport and accessible nanoporous channels for fast diffusion and transport of Li+ ions. This 0D-in-1D peapod-like Ge/CNx nanomaterial possesses a stable discharge capacity of 1080 mA h g−1 over 1200 cycles at a 0.5C rate (1C = 1600 mA g−1) and 62.3% capacity retention when the current density is increased 16 times from 0.5 to 8C, enabling promising applications in high-performance LIBs.