Interface Design To Construct High Specific Energy Density Alkali Metal Anode

Recently,due to the high energy densities and low redox potentials,alkali metals stand out as the anode materials from the competition.However,dendrite growth and serious safety hazards greatly restrain the commercialization of alkali metal anodes.These problems are mostly related to some defects at the eledtrode/electrilyte interface or the electrode/electrode modification interface,s uch as:uneven distribution of energy,potential,heat or ion flux at the electrode interface;accumulation of dendrites aggravating battery deterioration;weak adhesion or insufficient/uneven reaction between the traditional artificial SEI and electrode i nterface and difficulty in regulating the inorganic SEI,etc.This paper mainly proposes some new strategies to solve these practical issues from the perspective of interface design.The main works and results are as follows:(1)This paper firstly proposes the"interface dissolution repair"strategy,aiming at the problem of irreparable battery damage caused by the accumulation of dendrites at the interface of the alkali metal negative electrode for a long time.An asymmetric bidirectional current(ABCM)charging mode is designed by applying periodic reverse current at the right time during the lithium deposition process,allowing the dendrite to be repaired in time on the electrode surface before it deteriorates.Moreover,the cycle is repeated to achieve the purpose of inhibiting the dendrite growth.Experiments show that the ABCM route has significant advantages no matter in the ether electrolyte system or the ester electrolyte system.The combination of the dissolving effect of ABCM and the thermal repair effect under high current conditions is further investigated in this paper,and it was found that a more satisfactory interface repair effect could be achieved by appropriately increasing the current density during the recharge.(2)Aiming at the problem of poor adhesion or insufficient/uneven reaction at the interface between the traditional artificial SEI and the metal electrode,which is likely to cause the localized and violent growth of dendrites,this paper proposes a strategy of?interfacial densification covering artificial SEI?.Herein,self-catalysise piezochemistry induces the defluorination reaction between K metal and PTFE.The the liquefaction of K metal caused by reaction heat can achieve the purpose of leveling the electrode surface and deepening the reaction.As well as the repeated friction can uniform and densifying reaction.Experimentally,by repeatedly rubbing on the joint surface of K metal and PTFE film,this self-catalysise piezochemistry reaction can occur continuously,so that a continuous and compact protective layer can be constructed on the K surface.Under the protection of this layer,the CCPP anode exhibits significant advantages.(3)Because of the difficulties in regulating the growth thickness,uniformity and integrity of the inorganic layer in the traditional SEI construction process,this paper proposes a new strategy for constructing of"exsolution"SEI from the substrate interface.That is,by first growing a layer of lithophilic inorganic nanomaterials(such as Cu O etc.)uniformly on the 3D collector surface,and then contacting them with hot molten Li to undergo a replacement reaction.The replacement products,Li ₂O,etc.will slowly"dissolve"from the substrate interface to the electrode surface,forming a complete"exsolution"SEI layer with in situ coverage and uniform distribution.Under this SEI effect,the long-cycle performance and reversibility of the Li metal composite electrode are effectively enhanced.Furthermore,the application of different inorganic nanomaterials(such as Cu S,etc.)on the 3D collector has also confirmed that this"exsolution"SEI can be commonly fabricated,indicating that this strategy is of universal application value.