Fabrication And Electrochemical Performance Of Electrode Materials For Rechargeable Lithium Metal Batteries

Along with scarce fossil energy and worsening environmental pollution,lithium metal batteries?LMBs?have become a hot spot of research owing to its high-energy density.However,the adverse reactions of the LMAs and electrolyte lead to plating/stripping behavior of inhomogeneous Li-ion flux and uncontrollable growth of lithium dendrites on the surface of lithium metal anodes?LMAs?,which results in the problems of low coulomb efficiency?CE?,potential safety hazard and low discharging capacity.The LMAs are reacted with electrolyte inevitably to form a natural solid electrolyte interface?SEI?membrane.However,this natural SEI membrane has the defects of inhomogeneous composition and low mechanical strength so that it ruptures/reforms continuously and becomes unstable along with cycles.Facing the defects of natural SEI membrane,two kinds of artificial SEI?ASEI?membranes are fabricated to solve the problems of LMAs in this paper.For the first kind of ASEI membrane,the alginic acid and Li OH?H₂O were reacted to form Li alginate in dimethyl sulfoxide,and then the mixed solution composed of Li alginate and alginic acid was dropped and dried to form an Li alginate-based ASEI membrane onto the surface of the bare LMA?denoted as ASEI-Li?.The first kind of ASEI membrane is chemically stable,allowing easy Li-ion transport on the surface of the ASEI-Li and can suppress the growth of Li dendrites.The symmetric Li||Li cells with the ASEI-Lis can stably run for 850,350 and 120 h at current densities of 0.5,1 and 3 m A cm^-2,respectively.In addition,the Li Fe PO₄||Li full cells with the ASEI-Lis exhibit a capacity retention of about62.4%and 94.0%coupled with a CE of 99.7%and 99.6%after 500 and 1000 cycles at 0.6and 4 C,respectively.For the second kind of ASEI membrane,the bare LMA was needed to dip in the dimethyl carbonate?DMC?dissolved polyether polyol P123 to form an ASEI membrane that is composed by polyether polyol P123,Li₂CO₃and RO–CO₂Li on the surface of the bare LMA?denoted as P123-Li?.The ethylene oxide and propylene oxide groups of polyether polyol P123 can coordinate with Li-ion flux to regulate Li-ion plating behavior more homogeneously.The mixtures of Li₂CO₃and RO–CO₂Li can conduct Li-ion and decrease the adverse reactions of the LMAs and electrolyte.The symmetric Li||Li cells with the P123-Lis exhibit an improved cycling stability of 260 and 68 h without notable voltage fluctuation at current densities of 1 and 3 m A cm^-2with a capacity of 1 m Ah cm^-2,respectively.In addition,the Li Fe PO₄||Li full cells with the P123-Lis show a remarkable capacity retention of about 64.46%and 91.5%with the CE of 98.96%and 98.7%after 1000cycles at 1 and 4 C,respectively.In a word,compared with the bare LMAs,the protected LMAs fabricated by the proposals in this paper can improve the electrochemical performance.Further,it is suitable to be used in large-scale manufacture of rechargeable LMBs of high-energy density,long life in the future,owing to easy fabricating as well as environment-friendly.