Exfoliated multi-layered graphene anode with the broadened delithiation voltage plateau below 0.5 V

The commercial graphite (CG) is the conventional anode material for lithium ion batteries (LIBs) due to its low delithiation voltage plateau (below 0.5 V) and extraordinary durability. Nevertheless, the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG. Here, based on the supercritical CO2 exfoliation technique, the production of multi-layered graphene (MLG) is achieved from the pilot scale production line. The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG. Additionally, no obvious lithium dendrites are observed for MLG during the lithiation process. The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism, which is further confirmed by the density functional theory calculations. The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity, energy density and ultralong cycling stability (90% capacity retention after 500 cycles at 2 C), significantly better than that of LiFePO4/CG. Besides, this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.