Multi-scale Confinement Interfaces For High Performance Metal Anode-based Batteries

The increasing development of low-carbon economy has brought significant changes in global energy consumption.Renewable energy,such as solar energy,wind energy and geothermal energy,et al.,has gradually brought a development trend.Accordingly,developing electrochemical energy storage systems is very urgent to realize the efficient utilization of above intermittent renewable energy.At present,commercial LIBs is hard to meet the development of energy storage market in the future due to its low energy density,expensive price and limited lithium reserves.Rechargeable metal anode based batteries(Li,Na,K,Zn;3860m Ah g^-1,1166 m Ah g^-1,687 m Ah g^-1)have drawn wide attention due to its high energy density.However,the metal anodes have some drawbacks:（1）There are usually complex side reactions at the interface between metal anode and electrolyte（solid/liquid）due to the high reactivity of metal anode,which seriously bring damages to the specific capacity and coulomb efficiency of the battery.（2）The stripping/plating process during the charge and discharge will produce huge volume changes,resulting in the rupture of solid electrolyte membrane and the pulverization of electrode,as well as significant attenuation of battery performance and the rapid consumption of active substances.（3）The uneven plating of metal causes the generation of dendrites,which will not only accelerate the side reaction and volume expansion,but also cause the active substance to separate from the substrate,resulting in inactivation.Uncontrollable dendrites will even pierce the diaphragm,resulting in safety problems.Therefore,how to inhibit the side reaction,buffer volume expansion and dendritic growth of metal negative electrode is the core challenge to stabilize metal negative electrodes.In view of the above key problems,this work systematically studies the design,construction and performance enhancement of multi-scale confinement interfaces,and puts forward a new idea of inducing uniform metal deposition by regulating the confined adsorption and diffusion of ions at the electrode interface.First,a two-dimensional（2D）confinement film with controllable molecular thickness is fabricated through molecular self-assembly strategy.The dendrite-free metal deposition can be achieved by controlling the uniform diffusion of ions.Secondly,a three-dimensional（3D）confinement interface with highly dispersed metallophilic sites was constructed through in-situ growth strategy,and the directional deposition of various metals was realized.Finally,the super-wetting and stable confinement of liquid metal at room temperature are realized by using 3D confinement structured electrode,and the successful construction of long-life liquid metal cathode is realized.The research contents of this thesis are as follows:1.Preparation of two dimensional film with confined channel for high performance lithium-sulfur batteryLithium sulfur（Li-S）batteries have attracted extensive attention because of their high capacity,safety and cost-effective.However,the“shuttle effect”and the dendritic growth cause rapid attenuation of capacity.By assembling layered double hydroxides（LDHs）nanosheets and graphene oxide（GO）on commercial polypropylene（PP）separator,a two-dimensional ultrathin film（～30 nm）with atomic confinement space（～1.1 nm）was successfully constructed.In-situ Raman and molecular dynamics simulations confirmed that the confined channel in the LDHs/GO film effectively prevented the shuttle of polysulfides,promoted the uniform diffusion of Li⁺,and effectively inhibited the generation of Li dendrites.The assembled Li-S battery based LDHs/GO shows high initial discharge capacity(1092 m Ah g^-1)and cycle stability at 0.2 C.2.Preparation of two dimensional film with confined metal ions for high performance zinc metal batteryAqueous zinc metal batteries（AZMBs）have drawn wide attention due to its rich reserves,low redox potential,environment-friendly and high theoretical capacity.Nevertheless,the reversibility of zinc anode is poor,which is easy to produce dendrites and cause serious side reactions,thus hindering the practical application of AZMBs.In this part,a two dimensional interfacial film with highly dispersed confined zinc salts was prepared by co-assembling polyamide6,Zinc trifluoromethanesulfonate and LDHs in two dimensional channel.It significantly inhibited the dendrite formation,H₂ evolution and dissolved O₂corrosion.The prepared zinc anode has a cycle life of up to 1450 h and a low reversible deposition potential.In addition,the assembled zinc manganese battery has an initial capacity of up to 321 m Ah g^-1 and a high cycling life of590 cycles.This two-dimensional confined interface strategy can also introduce fluorescent molecules for in-situ visual observation of zinc anode during cycling,which provides a new method for in-situ study of the deposition behavior of Zn.3.Preparation of three-dimensional Ti O₂-F confinement interface for high performance metal anode batteriesThe large specific surface area of three-dimensional structure can reduce the local current density and inhibit the growth of dendrites.Moreover,its large buffer space can alleviate the volume expansion.We further proposed a strategy that monodisperse"F"heteroatom metallophilic sites（Ti O₂-F）were in-situ introduced into the Ti O₂ nanorod arrays to realize the confined nucleation and uniform deposition of metals.Density functional theory calculation（DFT）shows that the binding energy of Li⁺,Zn²⁺,Na⁺,K⁺on Ti O₂-F is greatly improved compared with Ti O₂,which significantly enhances the metallophlic of the material.Moreover,the three-dimensional structure contains large buffer space,which can alleviate the stress change of metal surface.Hence,the CC/Ti O₂-F electrode based Li,Na,K and Zn symmetrical cells have cycle life of 1100 h,530 h,720 h and 510 h respectively(2 m A cm^-2),which is 4.4 times,26.5 times,24.1 times and 25.5 times than that of CC based anode.This work provides a new idea for developing a general method for dendritic free metal anode.4.Preparation of three-dimensional Co-SACN confinement interface for high performance liquid metal batteryThe Co single atom carbon（Co-SACN）metallophilic sites with 3D arrays structure were constructed for the superwetting of liquid metals at room temperature.DFT calculation shows that the binding energy between K and Co-SACN in NAK alloy is much lower than that of Na,and the wetting process of Na K gradually accelerates with the increasement of K content in NAK alloy,revealing the wetting mechanism of K preferential adsorption.The 3D hierarchical structure enhances the domain confinement of Na K and prevents liquid leakage.The cycle life of Co-SACN@Na K in Na Cl O₄ electrolyte and KPF₆ electrolyte are 1200 h and 1000 h,respectively.When matched with the cathode of Na₃V₂（PO₄）₃,it can reach an ultra long cycle life of 5000 cycles at 1C and 16000 reversible cycles at 5 C,far exceeding the reported results.When matched with the potassium ion cathode,it also shows excellent cycle stability.In this work,the concept of liquid metal superwetting is proposed,which provides a new method for the development of dendritic free alkali metal batteries with long cycling life.