Application Of Three-dimensional Carbon-based Current Collector In Lithium Metal Anode

Lithium(Li)metal exhibits an encouraging theoretical capacity of?3860 m Ah g^-1and the lowest redox potential,being considered as the“Holy grail”of anode materials.Nevertheless,Li metal anode suffers dendrite growth and large volumetric change during repeated cycles,thus leading to continuous formation/break of solid electrolyte interphase(SEI)film,low Coulombic efficiency,fast capacity degradation and even severe safety hazards.The introduction of three-dimensional(3D)current collector into Li metal anode is an effective means to alleviate the above problems,we studied the application of carbon-based three-dimensional current collector in lithium metal anode.The main works are as follows:(1)Hollow graphene spheres were prepared as 3D current collectors using polystyrene nanospheres as the template,and then were compounded with Li through electrochemical deposition.As a conductive skeleton,the graphene sphere can uniform Li ions effectively,reduce local current density and induce Li to deposit homogenously.Meanwhile,it can also provide rich space to accommodate metallic Li and alleviate the volume change during cycles.In the coulombic efficiency test using ether electrolyte at1 m A cm^-2,the battery using graphene spheres as current collector can cycle stably above 220 cycles and deliver a Coulombic efficiency of over 97%.The composite anode also has better cycling and rate performance in the symmetric batteries.(2)A 3D hollow carbon tube(HCT)mat was fabricated from natural willow catkins to form HCT/Li composite through a scalable molten infusion method.The intrinsic heteroatoms endow the HCTs with excellent lithiophilicity and molten Li can be infused into 3D HCT mats easily via capillary driving force.Meanwhile,the conductive skeleton and large void space induce uniform Li deposition and accommodate volume change,promising a stable anode.The HCT/Li electrode could deliver an impressive gravimetric capacity?3026 m Ah g^-1 and a long-term stable cycling above 500 stable cycles at 2 m A cm^-2 in symmetric batteries using ether electrolyte.Furthermore,fast and stable charge/discharge was demonstrated in a full cell by pairing the composite metal anode with a lithium iron phosphate cathode.