많은 경험과 지식을 쌓을 수 있도록 도와주시고 부족한 부분들을 채워주신 교수님들께 감사드립니다. 그리고 연구실에서 잘할 수 있도록 도와준 영진이, 여러모로 도움을 주고 많은 시간을 함께 해준 수연이 덕분에 연구실 생활이 즐거웠습니다. 그곳에서 2년을 살았던 대학원 동창, 데오. 많은 어려움이 있었지만 잘 마칠 수 있어서 다행입니다.
박사님 감사합니다. 실험을 돕고 배려해 준 Rajesh. 나도 한동안 같이 있지는 않았지만, 나는 Dr. 또한 실험에서 빠진 부분을 자세히 설명해주시고 도움을 주신 Yuba에게도 감사드립니다. 그리고 질문이 많고 항상 물음표가 있는 지운이가 너무 열심히 해서 여러모로 부족했는데 1년 동안 잘 살아줘서 고맙다.
막내지만 누구보다 똑똑한 반군이 앞으로도 연구실 생활을 즐기길 바란다. 마지막으로 현아 누나를 위해 일하면서 대학원 생활도 쉽지 않을 텐데 열심히 하는 모습이 너무 좋다.
Also, the ionic conductivity of the garnet electrolytes can be improved by controlling the shape control. One of the effective physical properties of lithium-rich antiperovskites is stable with lithium anode . 34; Problems and Challenges Facing Rechargeable Lithium Batteries." In Materials for sustainable energy: a collection of peer-reviewed research and review articles from Nature Publishing Group, pp.
Busche, Joachim Sann and Jürgen Janek "Interphase formation and breakdown charge transfer kinetics between a lithium metal anode and highly crystalline Li7P3S11 solid electrolyte." Solid State Ionics. 34;Inorganic Solid State Electrolytes for Lithium Batteries: Mechanisms and Properties Controlling Ion Conduction." Chemical Reviews 116, No. 34;Ceramic Separators Based on Li+ Conducting Inorganic Electrolyte for High-Performance Lithium-Ion Batteries with Enhanced Safety." Journal of Power Sources.
34; Degradation of NASICON-type materials in contact with lithium metal: formation of mixed conductive interphases (MCI) on solid electrolytes." The Journal of Physical Chemistry C 117, no. 22] Wenzel, Sebastian, Thomas Leichtweiss, Dominik Krüger, Joachim Sann and Jürgen Janek "Interphasing on Solid Lithium Electrolytes - An In Situ Approach to Study Interfacial Reactions by Photoelectron Spectroscopy. Solid State Ionics. 34; Garnet-Type Solid State Fast Li-ion Conductors for Li Batteries: Critical Review." Chemical Society Reviews 43, no.
34;Characterization of the interface between LiCoO2 and Li7La3Zr2O12 in a solid-state rechargeable lithium battery." Journal of Power Sources 196, No. 34;A new ultrafast superionic Li conductor: ion dynamics in Li 11 Si 2 PS 12 and comparison with other tetragonal electrolytes of the LGPS type." Physical chemistry Chemical Physics 16, no. 34;Synthesis of new lithium ionic conductor thio-LISICON—lithium silicon sulfides system." Journal of Solid State Chemistry 168, no.
34; A First-Principles Study of the Lithium Superionic Conducting Material Li10GeP2S12." Materials Chemistry 24, No. 34; Negative Magnetocaloric Effect in the Antiferromagnetic to Ferromagnetic Transition of Mn 3 GaC." Journal of Applied Physics 94, no. 34; Phase Stability and Transport Mechanisms in the Antiperovskite Superionic Conductors Li3OCl and Li3OBr." Materials Chemistry 25, no.
34; Defect Chemistry and Lithium Transport in Anti-Perovskite Li 3 OCl Superionic Conductors.” Advanced Science 3, no.
And finally, electron detectors of any kind are placed in microscopes that collect signals to produce an image of the patterns . The size of the interaction volume depends on the value of the accelerating voltage of the primary electron beam and the atomic number of the sample. Secondary electrons are produced from the sample surface or the top part of the interaction volume and X-rays are generated within the entire interaction volume .
FE-SEM is used to visualize information of the local areas on the surface of chemicals. The combination can also visualize the element distribution in a sample through mapping that shows the concentration of one element over a selected area of images of the sample. Where Zre and Zim are the real and imaginary parts of the impedance in the Nyquist plot which is one of the methods to express impedance as Figure 2.3.
In the case of the solid electrolyte, the way to interpret the equivalent circuit is different. Where l is the thickness of a solid electrolyte pellet, R is the resistance, and A is the surface area of the pellet. Cyclic voltammetry is a typical technique that can measure the current flow by controlling the potential of the working electrode.
The configuration of the cyclic voltammetry cell mainly consists of symmetrical Li/electrolyte/SUS or Cu (reference/working/counter electrodes) . The stability of the solid electrolyte is evaluated by comparing the change in current as the voltage is scanned at a constant rate. This method is not accurate for comparing the degree of reaction of the solid electrolytes, but it is good at observing the reaction voltage of the electrolytes.
DC cycling measurement is one of the galvanostatic measurements such as galvanostatic charge-discharge and galvanostatic intermittent titration technique. During the galvanostatic cycles of batteries, the charge and discharge currents are often expressed as a C-rate which is a measure of the rate. 34;Li2OHCl crystalline electrolyte for stable metallic lithium anodes." Journal of the American Chemical Society 138, no.
Electrochemical performance of the mixed solid electrolyte (100-x)Li 3 SI-
For example, in the Tatsumisago et al. group, Li3PS4 and LiBH4 were mixed to increase stability with lithium metal and a solid electrolyte was synthesized that improved the conductivity of lithium ions . In the Xu et al. group, Li7P3S11 was doped with LiPO4 to reduce side reactions between the cathode and the solid electrolyte and to improve lithium ion conductivity. Inspired by the above research, we are inspired by the above experiment to synthesize a mixed solid electrolyte.
The mixed (100-x)Li3SI-xLi6PS5Cl(x and 30) solid electrolyte improved the stability of metallic lithium compared to Li3SI and Li6PS5Cl electrolytes and improved battery capacity and cycle stability when used for ASSLB. A Li-In alloy was used as the anode to prevent instability between metallic lithium and the solid electrolyte. Figure 1 shows the X-ray diffraction patterns of the (100-x)Li3SI-xLi6PS5Cl solid electrolyte mixed by the ball mill process.
SEM measurements were performed to observe the morphology of (100-x)Li3SI-xLi6PS5Cl mixed solid electrolyte. 70Li3SI-30Li6PS5Cl has a higher ionic conductivity than 80Li3SI-20Li6PS5Cl, however, as the interfacial resistance between Li-In and solid electrolyte increases, Li deposition/dissolution is complicated, which degrades the battery performance. As shown in Figure 4 and Figure 7, the battery performance is significantly improved compared to the case of using the single Li3SI solid electrolyte due to the improved ionic conductivity through the mixture.
In addition, the mixed solid electrolyte shows better performance by reducing the problem of contact resistance with the lithium metal occurring in the Li6PS5Cl single solid electrolyte . 80Li3SI-20Li6PS5Cl mixed solid electrolyte has lower ionic conductivity than Li6PS5Cl, 70Li3SI-30Li6PS5Cl, but 80Li3SI-20Li6PS5Cl improves stability over lithium metal and provides excellent all-solid battery performance. By the way, in the cycle holding graph in Figure 9(b), the cycle stability of the mixed solid electrolyte is better than that of the single solid electrolyte.
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Zhang et al., “Poly(ethylene oxide) reinforced Li6PS5Cl composite solid electrolyte for all-solid-state lithium battery: improved electrochemical performance, mechanical properties and interfacial stability”, J. Wan et al., “Nanoscaled Na3PS4 Solid Electrolyte for All-Solid- State FeS2/Na batteries with ultra-high 95% initial Coulomb efficiency and excellent cycling performance”, ACS Appl.