Research On Optimizing Substrates To Construct 3D Zn Metal Anode

Aqueous zinc ion battery possesses high security,lost cost and excellent performance,yet,the dendrite formation on Zn anode is a stumbling block on the road of development.Constructing three-dimension（3D）substrate is a valid method to relieve the formation of Zn dendrite.Nevertheless,some commercialized 3D current collectors behave a large nucleation barrier,leading to uneven nucleation and aggregative plating,thus forming“tip effect”.Aiming at the difficulty of 3D substrate,this paper modifies its surface with alloy layer to improve its affinity with Zn.Moreover,effectively integrates 3D collectors with alloying,thus improving the behavior of Zn deposition.The main research contents are as follows:（1）A tuned and zincophilic Cu-Zn alloy interfacial layer was synthesized on the surface of stainless-steel mesh（SS）by electrodeposition method.This Cu-Zn alloy layer can reduce Zn nucleation overpotential,inducing axipetally homogenous Zn plating.As a result,it exhibits excellent reversibility of Zn plating/stripping.The electrode can maintain a coulomb efficiency of 98.5%and run for 470 cycles at a current density of 2 m A cm^-2 with a capacity of 1 m Ah cm^-2.Assembled with CNT/Mn O₂as a full battery,it circulates for 350 cycles under the current of 1 A g^-1,with a capacity retention rate of 70%,while the 3D Zn anode without Cu-Zn layer modification has a retention rate of only 30%.（2）A uniformly distributed and spherical Cu-Sn alloy layer was devised by electrodepositing.Abundant spherical Cu-Sn alloy serve as nucleation seeds to induce uniform Zn plating.The Zn nucleation overpotential in initial cycle on the alloy layer is only 1 m V(2 m A cm^-2,1m Ah cm^-2),and this Cu-Sn alloy can convert into Cu-Zn alloy and metallic Sn spontaneously when compounding with Zn,enabling the densified Zn deposition layer.This Cu-Sn alloy framework can accommodate a large amount of Zn without changing the thickness of the fiber,which plays an ideal role of 3D collector.Similarly,as a 3D Zn anode after compounding with sufficient Zn,the symmetric battery can maintain a stable polarization voltage cycle for 1050 h at 10 m A cm^-2 with a capacity of 3 m Ah cm^-2.Assembled with sodium ion treated V₂O₅（NVO）as a full battery,it can maintain a capacity retention rate of 84%and cycle for more than 1000cycles at a current of 2 A g^-1.