High-performance lithium storage achieved by chemically binding germanium nanoparticles with N-doped carbon.

Abstract

Germanium (Ge) is a promising anode material for lithium ion batteries due to its high theoretical capacity. However, its poor cycling stability associated with its large volume changes during discharging and charging processes are urgent problems to solve. This provides opportunities to engineer materials to overcome these issues. Here, we demonstrated a facile and scalable method to synthesize Ge nanoparticles/N-doped carbon monolith with a hierarchically porous structure. The combination of a solvothermal method and annealing treatment results in a well-connected three-dimensional N-doped carbon network structure consisting of Ge nanoparticles firmly coated by the conducting carbon. Such a hierarchical architecture features multiple advantages, including a continuous conductive carbon network, binding the Ge nanoparticles with carbon through a Ge-N chemical bond, and a porous structure for alleviating volume expansion of Ge particles. When serving as an anode for lithium ion batteries, the as-formed hybrid displays high capacities up to 1240.3 mAh g(-1) at 0.1 A g(-1) and 813.4 mAh g(-1) at 0.5 A g(-1) after 90 cycles, and at the same time, it also exhibits good cycling stability and excellent rate capability.