Quantitative Characterization Of Interfacial Adhesion Properties Of Sulfide Electrode Materials

In order to cope with global warming,my country proposed the goal of achieving carbon peaking by 2030 and carbon neutrality by 2060 in September 2020,and released the "14th Five-Year Plan for New Energy Storage Development Implementation Plan".Driven by relevant policies,it is necessary to focus on building a clean,low-carbon,and efficient energy system to reduce carbon dioxide emissions.With the rise of the new energy industry,especially in the direction of electric vehicles.The battery is the heart of electric vehicles,and its development will be the focus of human attention in the next few decades,especially lithium-sulfur batteries with high energy density and large capacity.However,the sulfur electrode of lithium-sulfur battery will generate polysulfides with complex composition during the charging-discharging and cycling process.The interface of this material is prone to failure and peeling,which leads to the shuttle effect,resulting in poor cycle performance,which is one of the main reasons hindering the commercial application of lithium-sulfur batteries.The cycle performance of batteries is closely related to the interfacial bonding strength of electrode materials,which can be characterized by macroscopic methods such as tensile method,indentation method,and exfoliation method.It is still difficult to grasp the essence of the failure of sulfide electrode materials at the stage of empirical experiment and numerical simulation exploration,and there is currently a lack of effective theoretical model prediction and in-situ experimental characterization methods.Under this background,this paper uses the bond order-length-strength theory to expand the elemental material system to the polysulfide heterointerface material system,and establishes the functional relationship between the bond length and bond energy of the sulfur electrode and polysulfide,and then combined with photoelectron spectroscopy to quantify its interface adhesion properties.The main research results obtained in this paper are:(1)A new method to characterize the interfacial adhesion properties of sulfur electrodes and polysulfide heterointerface material systems is proposed.This method links the macroscopic properties and microstructures to quantitatively characterize the interfacial binding properties of sulfur electrode materials for lithium-sulfur batteries at the micro-atomic level.Through this method,the inherent properties of some common elements such as isolated atomic energy levels and bulk offsets are analyzed,physical information such as bond energy,atomic binding energy,and electron relaxation kinetics at the interface under the atomic structure are obtained,and the binding energy of heterointerfaces between active material species are calculated.(2)Based on the intrinsic properties of the element,the photoelectron spectrum of the binary sulfide electrode material was analyzed,and the interfacial adhesion properties of sulfide and disulfide were obtained.The interfacial binding energy of MnS in sulfides is the largest,which is 6.12 J/m2.The sulfides’ interfacial binding energies are ranked as:MnS>ZnS>CuS>CS.The interfacial binding energy of FeS2 in disulfides is the largest,which is 5.97 J/m2.The disulfides’ interfacial binding energies are ranked as:FeS2>MoS2>SnS2.The magnitude of the interfacial binding energy of binary sulfides may be related to the metallicity and atomic radius of the corresponding element.(3)Extending the theory of this method and applying it to the calculation of interfacial adhesion properties of ternary sulfide electrode materials.The interface binding energies of the Mo1-XReXS、MoS2/CuS and MnS/CuS interfaces are 11.68,6.59 and 6.77 J/m2,respectively.It is found that the interfacial binding energy of ternary sulfides is increased compared with that of binary sulfides,and through the Mo1-XReXS ternary interface doped with rhenium element the ReS interface binding energy of is 5.74 J/m2 when X=1.Its value is smaller than the Mo1-XRexS ternary interface binding energy,indicating that Re doping improves the bonding between ternary interface atoms.