Interface Modification And Mechanism Research Of Lithium Metal Anode|solid State Electrolyte

The increasing demand for superior energy storage devices renders the traditional lithium-ion batteries incapable for our future needs,especially in the sense of superior capacity and higher safety standard.And breakthroughs in all-solid-state lithium batteries provide some possibilities.Garnet-type solid electrolytes are widely concerned due to their excellent properties?high ionic conductivity and chemical stability to metallic lithium,etc.?.We investigated and solved the main interface problems using LLZTO(Li_6.4La₃Zr_1.4Ta_0.6O₁₂)solid electrolyte,including mainly three different aspects:?1?The interfacial wettability between Li and LLZTO pellet was achieved via the addition of trace amount of Na,interfacial resistance,from 1 k?·cm² to1?·cm²;?2?The interfacial stability at high current density was sustained through an interfacial protection layer formed by aluminum?Al?diffusion at low temperature?245 ^oC?toward the Li|LLZTO interfacial layer;?3?On the basis of the above,we designed and employed the in situ optical and transmission electron microscopes to study the growth of Li dendrites in LLZTO.During these projects,we developed some new experimental techniques aiming to tackle the physical and chemical properties of Li,SSE,and their interface.For example,we employed the electrochemical stripping of Li to thoroughly separate Li and LLZTO and to sustain an uncontaminated interface,in order to analyze the interface with X-ray photoelectron spectroscopy?XPS?;we designed and built a special in situ electrochemical cell,which enable us to observe the lithium dendrite growth in the opaque SSE under an ultra-depth optical microscope.Within this thesis,we combined a series of characterization techniques?e.g.,scanning electron microscope?SEM?,transmission electron microscope?TEM?,X-ray photoelectron spectroscopy?XPS?,and Fourier transform infrared spectroscopy?FTIR??with DFT theoretical calculations,and explored carefully the mechanisms of wettability,surface protection,and growth of lithium dendrites.The results for this systematic study shed light on the future development of all solid-state lithium batteries.