The Surface Modification Of The Current Collectors For Dendrite-free Lithium Metal Anodes

Lithium metal is considered to be the most ideal negative electrode material for rechargeable batteries due to its high energy density and low oxidation-reduction potential.However,the practical application of lithium metal negative electrodes faces the problems of uncontrollable growth of lithium dendrites and volume expansion.This thesis used gold nanoparticles and gold nanoparticle composite carbon nanotubes/graphene to modify copper foam and copper foil respectively,the effects of these two current collector modification processes on the deposition behavior of lithium and the performance of lithium metal anodes were discussed.By electrostatic adsorption,we have successfully prepared gold nanoparticles modified copper foam(Au@Cu foam).This three-dimensional current collector has good lithiophilic property,and the existence of gold nanoparticles can induce the uniform nucleation of lithium.Combining with the mitigating effect of three-dimensional current collector on the volume expansion of lithium,the formation of lithium dendrites is significantly inhibited during the deposition process.Compared with the commercial copper foam,the Coulomb efficiency(CE)and cycle stability of Au@Cu foam 3D current collector have been significantly improved.The CE can be stabilized at more than 98%,and the lifespan of its symmetrical battery can be up to 1000 hours.Using electrophoretic deposition,we fabricated the gold nanoparticles composite carbon nanotubes/graphene modified copper foil.Using lithiophilic gold nanoparticles and carbon nanotube/graphene three-dimensional network structure,which can provide the uniform deposition of metallic lithium and reduce local current density.The above advantages can inhibit the formation of lithium dendrite and receive a significant boost of CE and cycle stability.And the lifespan of its symmetrical battery can be up to 1000 hours.In summary,the uniform deposition of lithium metal was successfully achieved in this thesis by surface modification of two commercial collections(copper foam and copper foil),which effectively inhibited the formation of lithium dendrites in the charge-discharge cycle,and significantly improved the CE and cyclic stability.