AAA Carbon battery.Research on preparation methods and transmission technology of sulfide cathode materials and solid electrolyte mixtures for lithium batteries

　　All-solid-state lithium-ion batteries use solid electrolytes instead of traditional liquid organic electrolytes, effectively avoiding the hidden dangers of traditional lithium-ion batteries in terms of safety, thermal stability and electrochemical stability, making them suitable for large batteries and ultra-micro ultrasonic batteries. Thin battery fields have considerable application potential. However, the solid-state batteries currently studied are far inferior to liquid lithium-ion batteries in terms of rate performance and cycle performance. This is due to the greater interface contact resistance between the electrode and the solid electrolyte in the solid-state battery, and the grain boundary resistance determines the overall ionic conductivity of the electrolyte. rate, so the interface compatibility problem mainly affects the electrochemical performance of the battery. However, there are not many effective methods to characterize the solid-solid interface in current all-solid-state batteries. Solid-state NMR is a non-destructive and highly selective testing method for materials. It mainly examines the interaction between atomic nuclei and the local microenvironment of each atom through the chemical shift changes in the solid-state NMR spectrum, thereby effectively Detect bulk phase information in battery materials (electrode materials and solid electrolytes). Solid-state NMR can detect the spontaneous lithium ion exchange in lithium-containing multi-phase battery material systems (such as between multiple lithium-containing electrode materials or between lithium-containing electrode materials and lithium-containing electrolytes), thereby obtaining charges at the multi-phase interface. Selective information transmitted in. The structure of an all-solid-state lithium-ion battery includes a positive electrode, an electrolyte, and a negative electrode, all of which are composed of solid materials. Li6PS5X (X=Cl, Br) is a fast lithium-ion battery with high room temperature conductivity (>10-3S/cm). Ionic conductor, suitable for solid electrolytes in all-solid-state lithium-ion batteries.

　　【Achievements Introduction】

　　Recently, Professor Marnix Wagemaker (corresponding author) of Delft University of Technology in the Netherlands (Dr. Yu Chuang and Dr. Swapna Ganapathy are co-first authors) published an article titled "Accessing thebottleneckinall-solidstatebatteries, Li-iontransportovertheinterfacebetweenthesolid-electrolyteandelectrode" in Nature Communications magazine . This paper uses the two-dimensional lithium ion exchange solid-state nuclear magnetic method to study the spontaneous lithium ion transport between the sulfide cathode material (Li2S) and the solid electrolyte (Li6PS5Br) interface, thereby studying the preparation method and method of the sulfide cathode material and solid electrolyte mixture. Effect of battery cycle times on lithium ion transport between Li2S and Li6PS5Br. Research results show that the interface conductivity between the two materials depends heavily on the preparation method of their mixture, and charge and discharge cycles will destroy the interface contact between the two and increase the energy barrier for lithium ion diffusion, resulting in a decrease in the interface conductivity. decrease.

　　[Picture and text introduction]

　　Figure 1. Chemical treatment processes of all-solid-state battery materials at different stages and their capacity retention rates at corresponding stages.

　　a. Treat the battery cathode-electrolyte mixture through simple mixing, ball milling, and heat treatment (Ⅰ simply mixed micro-Li2S, Ⅱ simply mixed nano-Li2S, Ⅲ ball milled blended nano-Li2S, Ⅳ heat treated blended nano- Li2S).

　　b. Battery capacity after cyclic charge and discharge of the electrode-electrolyte mixture at the above different treatment stages.

　　c-f. Charge and discharge curves of the electrode-electrolyte mixture at the above different treatment stages (charge and discharge current density 0.064mAcm?2, voltage window 0-3.5V).

　　Figure 2. NMR test of spontaneous transmission of lithium ions at the Li2S cathode-Li6PS5Br solid electrolyte interface

　　a.e.i. One-dimensional 7Li magic angle rotation MAS spectra corresponding to the electrode-electrolyte mixture at the above different processing stages (I-III).

　　b.c.d. Two-dimensional 7Li-7Li solid-state nuclear magnetic exchange spectrum corresponding to the electrode-electrolyte mixture in sample processing stage I.

　　f.g.h. Two-dimensional 7Li-7Li solid-state nuclear magnetic exchange spectrum corresponding to the electrode-electrolyte mixture in sample processing stage II.

　　j.k.l. Two-dimensional 7Li-7Li solid-state nuclear magnetic exchange spectrum corresponding to the electrode-electrolyte mixture in sample processing stage III.

　　(Among them, the sample I-II is simply mixed does not have an obvious "anti-diagonal anti-cross peak", indicating that the lithium ion exchange effect is weak in the process, while the "diagonal anti-cross peak" of the sample III mixed by ball milling appears at 10ms, indicating obvious lithium ion exchange at the cathode-solid electrolyte interface.)

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