3D Nanoarchitecture of Ge/C Core-Shell for Ultra-High Rate Anode for Lithium Ion Batteries

The mobile world depends on lithium ion batteries (LIBs), which provide portable power for variety of applications, ranging from personal electronic devices such as laptops, mobile phones and digital cameras to electric vehicles due to their high energy density, low self-discharge and long cycle life.

Currently, the anode material in commercially available LIBs is made of graphite, which has the specific capacity of 372 mAh/g, but it cannot meet the world’s growing demand for batteries with higher energy density, power density and rate capability. For further increasing the energy and power density of LIBs, the replacing graphite carbon anode by new advanced materials with higher reversible capacity and rate capability as well as long-term cyclability is considered an attractive route. In this context, the lithium alloys based material emerged as a promising alternative candidate to replace graphite as an anode material for LIBs due to their high specific capacity.

Here, we propose a facile method to prepare 3D nanoarchitecture of carbon coated Ge (3D-Ge/C) using simple method. The 3D-Ge/C constructed from secondary particles of Ge/C composite with diameter of about 100 nm that composed of nanometer-size (~10 nm) primary particles of Ge coated with carbon. Through carbon coating on the nanosized Ge, the aggregation of Ge particles in nano scale is completely prevented. As a result, outstanding capacity and rate capability can be achieved with this structure, 3D-Ge/C exhibited a high reversible capacity of 1604 mAh/g at the rate of C/10 after 100 cycles and excellent rate capability. In particular, at high rate of 100C (160 A/g) the average capacity of 1122 mAh/g was observed and at ultrahigh rate of 400C (640 A/g) the average capacity of 429 mAh/g was recorded.