One-step, continuous synthesis of a spherical Li4Ti5O12/graphene composite as an ultra-long cycle life lithium-ion battery anode

We report, for the first time, a one-step, continuous synthesis of spherical lithium titanate (Li4Ti5O12, LTO)/graphene composites through direct aerosolization of a graphene oxide (GO) suspension mixed with Li and Ti precursors. The resulting crumpled graphene-sphere-supported LTO nanocrystals has a three-dimensional structure with a high electrical conductivity, a high surface area and good stability in electrolyte. The LTO/CG composite, as an anode in LIBs, exhibited excellent rate capability (for example, at a high current density of 5000 mA g−1 it delivered 60% of the capacity obtained at 12.5 mA g−1) and an outstanding cycling performance (a capacity retention of 88% after 5000 cycles at 1,250 mA g−1). The one-step, continuous synthesis of the LTO/graphene composite offers a high-producing efficiency compared with conventional multi-step preparations, and can be generally applied for synthesizing lithium metal oxides/graphene (cathode or anode) materials for lithium-ion batteries. Researchers have used ‘crumpled’ graphene spheres dotted with nanocrystals to boost the safety and performance of Li-ion batteries. Lithium titanate (Li4Ti5O12 or LTO) is a promising alternative to conventional Li-ion battery anodes that is less prone to dangerous short-circuit reactions, but it suffers from poor conductivity. Junhong Chen and co-workers from the University of Wisconsin-Milwaukee have developed a one-step synthetic technique to remedy this situation. By passing aerosolized graphene oxide and LTO precursors through a high-temperature furnace, normally flat graphene sheets transformed into crumpled spheres covered with LTO nanocrystals. The hollow, three-dimensional structure of this anode significantly improved LTO conductivity by shortening distances needed for charge transfer. Furthermore, the integrated composite prevents premature nanocrystal aggregation, giving rise to long device lifespans — prototype batteries retained 88% of their capacity after 5,000 recharge cycles. A one-step and continuous method to produce a spherical Li4Ti5O12/graphene composite for the lithium-ion battery anode is reported. The high conductivity and hollow structure of the crumpled graphene sphere greatly enhance the rate capability and cycling performance of the Li4Ti5O12 anode. This method provides a new and exciting approach for high-performance anode material design and fabrication.