Goodenough teach you how to design solid-state electrolyte
With the rapid development of electric vehicles, high energy density alkali metal ion batteries are more and more attention. However, the conventional liquid electrolyte, unstable deposition behavior of alkali metals and dendrite growth will trigger a series of security problems, which seriously hindered the development of alkali metal ion battery. In contrast, the solid electrolyte because of its excellent chemical stability, non-flammability, mechanical properties, not only the perfect solution battery safety issues, and may be a high-pressure metal anode and the cathode to match a high energy density is obtained all-solid battery. Therefore, the design of high-performance solid electrolyte with high energy density is essential for the development of all-solid-state battery. Recently, University of Texas at Austin Professorteam in the development and design high-performance solid-state electrolyte for solid state lithium-sulfur batteries [123 ] and all-solid-state sodium ion battery and achieved significant progress in 2020, two bursts of May 13, \”advanced functional materials.\” Let us follow Professor Goodenough learn how to design high-performance solid-state electrolyte. 1 AFM:. Reaction Mechanism PEO based solid Li-S battery Optimization
because of their good interfacial compatibility, excellent electrochemical stability, and high lithium ion conductivity, polyethylene oxide (PEO) based solid polymer electrolyte (SPE) are widely used in solid-state Li-S battery. However, PEO and a polyether having a molecular structure similar to a liquid electrolyte, and PEO-based solid-state Li-S battery lithium polysulfides behaves like a liquid electrolyte having a conventional Li-S battery. Thus, the effect can still cause the shuttle PEO based solid Li-S battery capacity and low coulombic efficiency of the fast decay (the CE), especially cell operating at a temperature above the melting point of PEO time. Despite the addition of inorganic filler particles, such as SiO2, TiO2, Al2O3, and of ZrO2, polysulfide can be adsorbed to some extent, thereby improving cycle performance of solid Li-S battery, but soluble polysulfide shuttle effect of these cells are still presence. Studies have shown that the body is strongly influenced number (DN) polysulfide reduction / oxidation reaction solvent by Gutmann supply. DN high solvent such as dimethyl sulfoxide (DMSO) and N, N- dimethylformamide (DMF), stable long-chain polysulfide (S82- and / or S62-), to facilitate Li2Sn (n> 4) formation and dissolution. And the short-chain polysulfide (S42-) DN is low in a solvent such as tetrahydrofuran (THF), 1,2- dimethoxyethane (DME), and 1,3-dioxolane (DOL): DME) dominated. Accordingly, the solvent of low DN may prevent the formation of long chain polysulphide. Since the PEO has a strong solvent properties, and ethylene oxide (EO) DN unit is relatively high (DN = 22), has a long chain polysulphide formed in the cell cycle have serious inPEO shuttle effect. Thus, by introducing a low DN polymer PEO based solid electrolyte may be a multi-step reaction pathway from the transition \”solid – solid – liquid\” one-step \”solid – solid\” reaction solution so as to achieve a solid Li-S battery shuttle effect purpose. In view of this, Austin Li Yutao and Prof. Dr. Goodenough University of Texas introduced low sulfur cathode DN polyvinylidene fluoride (PVDF) coating, significantly improves the performance of PEO cyclic group Li-S battery. Achieved in step PEO based solid Li-S cell \”solid – solid\” reactor, having a long cycling stability for the development of high energy Li-S battery provides a new way. Highlights Article:
- Low solvent properties result in long chains of PVDF PVDF insoluble polysulfides, not only inhibits the formation of soluble polysulfides, and sulfur reaction mechanism changes from the multi-step \”Solid – liquid – solid \”The reaction into a single step\” solid – solid \”response. After
Li-S battery containing a solid coating of PVDF rings 60 cycles at 0.05 mA cm-2 and 55 ℃, can be maintained 630 mAh g-1 reversible discharge capacity and coulombic efficiency up to 99%.
DFT calculation results show that the polysulfide polymer is insoluble and unstable in the PVDF, thereby promoting elemental sulfur during the cycle directly into solid Li2S2 / Li2S, thereby bypassing the high solubility of polysulphides formation, to significantly improve the electrochemical performance.
Reference: Reaction Mechanism Optimiz… Ation of Solid-State Li-S Batteries with a PEO-Based Electrolyte Adv Funct Mater 2020, 2001812. DOI:. 10.1002 / adfm.202001812 description link: https: //onlinelibrary.wiley.com/doi/10.1002/ adfm.202001812 2 AFM:. rT laminated composite having an all-solid electrolyte battery sodium
all-solid-state battery due to sodium ion significant cost and security advantages of widespread concern to researchers. Currently, the solid electrolyte covering mainly the following three categories: a ceramic (glass or ceramic) an inorganic electrolyte, an organic electrolyte and a polymer-based polymer-ceramic composite electrolyte. Wherein the ceramic inorganic electrolytes generally have a high ionic conductivity, good chemical / thermal stability, wide electrochemical stability range and low electronic conductivity. However, they are inelastic, designed mainly for hard batteries, these batteries can be hard to work in harsh environments. In contrast, since an elastic, organic polymer electrolytes having various geometric shapes suitable for flexible cell design, and the production process simple and low cost. In addition, the battery having a polymer-based electrolyte component can be reduced maximally electrode – electrolyte interface charge transfer key issues and the like. However, the ion conductivity of the polymer electrolyte is relatively lower than the ion conductivity of the ceramic inorganic electrolytes. Although the advantages of both the polymer-ceramic composite electrolyte ceramic inorganic electrolyte organic electrolyte and a polymer matrix, but so far still unable to meet all-solid battery sodium ion in ionic conductivity, mechanical properties, electrochemical stability and thermal stability required performance. Recently, two-layer electrolyte respectively by having an anode and a cathode friendly features friendly features binding strategies have been developed for all-solid-state lithium-ion batteries. Inspired, University of Texas at Austin Professor Arumugam Manthiram and Professor Goodenough proposed a sodium ion conductive laminated polymer / polymer solid electrolyte ceramic design for the development of all-solid at room temperature sodium batteries. The negative electrode side of the anode-friendliness polyethyleneoxide(PEO) as a polymer matrix and incorporated succinonitrile (SN) in order to improve the sodium ion conductivity at room temperature. The positive electrode side, a cathode-friendly polyacrylonitrile (PAN) used as the polymer matrix, incorporating therein the NASICON ceramic solid electrolyte (Na3Zr2Si2PO12) powder to enhance conductivity and the sodium ion sodium prevent electrolyte permeating through the dendrite membrane. The work of designing high-performance solid-state solid-state electrolyte sodium ion battery provides a new way for. Highlights Article:
- lamination method not only effectively avoids the electrochemical and chemical incompatibility between the electrode and the electrolyte, can also improve the ionic conductivity at room temperature sodium in each of the electrolyte layer, and the two solid sodium ion conductivity of the electrolyte layer is adjusted to a level matching. Furthermore, adding the additive in the polymer matrix ceramic phase helps to suppress the growth of dendrite sodium.
at room temperature, Na + ion conductivity of the solid electrolyte laminated to provide 1.36 × 10-4 S cm-1, the electrochemical window range 0-4.8V.
Further sodium metal anode, a high-pressure Prussian blue Na2MnFe (CN) 6 as the positive electrode and the laminated all-solid electrolyte assembly sodium ion battery, exhibits excellent cycle stability, cycle 200 cycles at 0.2 C rate capacity retention rate was 83.3%, and the entire Coulomb efficiency of the process has been maintained at 98.5-99.9%.
Reference:… Ambient-Temperature All-Solid-State Sodium Batteries with a Laminated Composite Electrolyte Adv Funct Mater 2020, 2002144. DOI:. 10.1002 / adfm.202002144 link description: https: //onlinelibrary.wiley.com/doi/10.1002/adfm.202002144