Preparation of ultrathin graphene film via capillary liquid bridge for uniform lithium nucleation in anode free lithium metal battery

Construction of graphene nanosheet films (GNF) with different thickness is highly important for their various applications. Construction of uniform GNF with defined thickness in nanoscale and large size remains challenge. Herein, a facile liquid bridge of capillary array is firstly designed to facilitate the oriented self-assembly of GNF. It is found that the self-assembly of GNF can be well controlled by Marangoni coefficient, in which the characteristic length (R) of liquid bridge for rapid spreading of trace solution on the Cu foil can be a controllable factor. As a result, the GNF with large-area (m2 level) and high-precision thickness (tens of nanometers) has been prepared. Taking the GNF on Cu substrate as lithium deposition electrode, the uniform Li nucleation and orientation growth can be realized to eliminate the growth of lithium dendrites, ascribing to the high lithiophilic of graphene. In the anode-free Li-LiFePO4 battery, the Coulombic efficiency (CE) of the first cycle can reach 88% at a cathode loading of 3 mg cm–2 and a current of 1 C, while the average CE can reach 99.1% within 100 cycles.