石榴石型固态电解质Li7La3Zr2O12的改性研究现状

固态电解质是高安全性、高能量密度的全固态锂电池的核心部件,其典型代表Li₇La₃Zr₂O₁₂(LLZO)具有高离子电导率、高机械强度、高电化学稳定性、低界面阻抗以及对锂金属负极良好的稳定性等优势,是科研人员重点关注的对象之一,但与液态电解质相比,目前LLZO仍存在低离子电导率和与电极固-固界面接触等问题。本文主要简介了LLZO的晶体结构、改性方式等对其离子电导率及界面阻抗的影响,同时对LLZO现存的问题进行了总结,对LLZO的未来发展方向进行了展望,为探索全固态锂电池的实际生产应用提供理论指导。     

Al3+掺杂石榴石LLZO固体电解质的制备及电化学性能研究

固体电解质拥有较高的离子电导率、良好的化学稳定性、长的循环寿命以及安全可靠等优点，被广泛应用到各个领域，成为当前研究的热点。以LLZO固体电解质为研究对象，制备了不同含量Al掺杂的LLZO电解质材料，采用X射线衍射、扫描电镜和交流阻抗谱等方法对不同掺杂量和不同烧结温度下LLZO固体电解质的XRD、微观形貌及电导率进行了研究。结果表明：少量Al的掺杂可以明显地提升LLZO固体电解质的电导率，但随着掺杂量的增加，Al3+增多，阻塞了Li+的传输通道，导致电导率下降。同时，烧结温度对材料的性能也有一定影响，随着烧结温度的提升，同一含量Al掺杂LLZO的致密度和电导率也有明显提升。     

Ta、Ba共掺杂石榴石型Li7La3Zr2O12电解质的制备及性能研究

传统锂离子电池采用有机电解液体系,能量密度难以进一步提升,同时存在一定的安全隐患。采用无机固体电解质构建全固态锂电池,在提高电池能量密度同时可兼顾安全性问题。在众多无机固体电解质中,Li₇La₃Zr₂O₁₂(LLZO)石榴石电解质具有离子电导率高、与金属锂接触稳定等优势,成为受人关注的材料。为了进一步提高该材料的导电性,采用固相法合成Ta、Ba共掺杂LLZO(Li_7-x+yLa_3-yBa_yZr_2-xTa_xO₁₂)电解质,采用X射线衍射、扫描电子显微镜和电化学阻抗法分析样品的物相结构、微观形貌及离子电导率。结果表明,Ta⁵⁺掺杂能够稳定立方相结构,Ba²⁺作为掺杂剂和烧结剂,促进晶粒生长和陶瓷致密化,从而降低总电阻。其中,Li_6.45La_2.95Ba_0.05Zr_1.4Ta_0.6O₁₂样品在室温下的总电导率为1.07×10^-3 S·cm^-1,活化能为0.378 eV。Ta⁵⁺/Ba²⁺共掺杂有利于制备高致密度和高电导率的石榴石型电解质材料。     

锂电池固态电解质新材料问世

近日,丰田中央研发实验室开发了一种有望用于高功率和高能量的全固态锂离子电池的固体电解质新材料。该材料用于正极为钴酸锂、负极为锂单质的锂离子电池时,具有优异的充放电性能和循环性能。全固态锂离子电池以传统固体氧化物作电解质时,比有机电解液和固体硫化物中的离子电导率低很多。该电解质不仅有高的化学稳定性和宽的电化学窗口,而且在室温下的离子电导率比有机电解液的电导率还高出两个数量级。该固体电解质与正极不会发生副反应和材料剥离,且界面阻抗能低到和普通的液态锂离子电池接近,但界面阻抗的活化能小很多。     

硫化物固态电解质电化学稳定性研究进展

锂离子电池固态化在大幅提高安全性的同时可兼具高能量和高功率密度,在电动车、国防等领域具有重大的应用前景。在实现全固态锂电池的3种固态电解质体系中,硫化物固态电解质由于具有最高的离子电导率、较好的机械延展性以及与电极良好的界面接触等优点,成为最具潜力的技术方向。然而其空气稳定性和电化学稳定性较差,尤其是后者直接限制了其在高能量密度全固态锂电池中的应用。通过从实验及理论计算两方面总结归纳了迄今为止关于硫化物固态电解质电化学稳定性的研究进展,并对现有提升硫化物固态电解质电化学稳定性的实验思路和理论结果进行了总结。     

锂磷酸盐微晶玻璃固体电解质材料研究进展

锂磷酸盐微晶玻璃固体电解质具有合成简单,电化学稳定性高等优点,已经对其进行了大量的研究工作。结合近几年的研究,分别综述了三元、四元和五元3种不同系统的锂磷酸盐微晶玻璃固体电解质所具有的最大电导率。并描述了Nasicon结构的快离子导体和交流阻抗谱在计算电导率上的应用。锂磷酸盐微晶玻璃固体电解质在全固态锂离子电池中将会有更广泛的应用。     

固态聚合物电解质性能提升方法的研究进展

商用锂离子电池由于使用危险和易燃的液体电解质,容易发生火灾和泄漏问题,存在安全隐患。全固态锂离子电池由于其安全性和潜在的高能量密度优势,被认为是下一代能量存储设备。固态聚合物电解质作为全固态锂电池的关键部件,具有良好的不可燃性和对锂金属阳极的适应性,近年来受到广泛关注。但其离子导电性低、力学性能差以及循环寿命不足等限制了其实际应用。根据近年来的研究进展,本文总结了优化固态聚合物电解质性能的方法,包括增加离子电导率,提高电压稳定性、抑制枝晶形成、增加离子选择性和降低界面电阻等,并简要分析了聚合物电解质的现状和发展前景,为固体聚合物电解质基电池的广泛应用奠定了基础。     

全固态锂电池关键材料—固态电解质研究进展

全固态锂电池具有能量密度高、循环寿命长和高安全性等优点,成为当前的研究热点。固态电解质是全固态锂电池的核心,主要包括氧化物、硫化物、聚合物以及复合型固态电解质。当前,发展全固态锂电池的关键是设计和制备具有高离子电导率的固态电解质,解决固态电解质与电极间的固–固界面问题。本文综述了全固态锂电池固态电解质以及固态电解质与电极间固–固界面的稳定兼容问题的最新进展,并展望了未来全固态锂电池的研究重点和发展方向。     

Al稳定立方相Li_7La_3Zr_2O_(12)固态电解质的场助烧结制备

石榴石型结构的固态电解质Li_7La_3Zr-2O_(12)(LLZO)因其良好的力学性能、化学稳定性、高离子电导率等特点有着广阔的应用前景。Li_7La_3Zr-2O_(12)(LLZO)具有四方相和立方相两相,其中立方相比四方相有更高的离子电导率(~10~(-3) S/cm)。本文利用场助烧结的制备方法,通过在Li_7La_3Zr-2O_(12)(LLZO)体系中掺杂Al~(3+)来稳定立方相的生成,制备了高离子电导、高致密的立方相Li_7La_3Zr-2O_(12)(LLZO)电解质,探究了Al~(3+)在立方相LLZO中的存在形式。实验采用FESEM、XRD、NMR和交流阻抗等方法研究了固体电解质的表面形貌、物相、Al~(3+)的存在形式及离子电导率。实验结果表明,在1150℃烧结温度下,Al2O3含量为1.5wt.%时,LLZO在室温下具有最高的离子电导率5.7×10~(-4) S/cm,Al位于LLZO晶粒中取代四面体中的Li,且相对密度约为99.8%。     

应用于锂离子电池的无机晶态固体电解质导电性能研究进展

固体电解质是电解质材料的一个重要种类,利用固体电解质组装全固态电池是解决锂离子电池安全性差,能量密度低等问题的有效方法。围绕着几类重要的无机晶态固体电解质,包括：钙钛矿型、钠快离子导体型(NASICON)、锂快离子导体型(LISICON)、硫代–锂快离子导体型(thio-LISICON)、石榴石型,对晶体结构、合成工艺及其与电极材料匹配性能的研究进展进行综述,并着重讨论了无机晶态固体电解质应用于锂离子电池的导电机理以及提高离子电导率的原则与方法。     

Effect of Li2O excess in Li6.4Ga0.2La3Zr2O12 electrolyte for all-solid-state Li-ion batteries

Li₇La₃Zr₂O₁₂ is a promising material used as solid electrolyte in all-solid-state lithium batteries. However, the lithium ionic conductivity of LLZO is limited, and the cycling stability of lithium symmetric battery based on LLZO is not good. In this research, different Ga-doped LLZO samples were prepared by adding different excess amounts of Li₂O, and the effect of excess amount of Li₂O on the structure and performance of LLZO have been researched. The results show that with the rise of the amount of Li₂O, the lithium ionic concentration increases gradually, and the lithium ionic conductivity and the ratio of grain resistance to total resistance rise first and then drop. When the excess amount of Li₂O is 10 wt.%, the sample exhibits the highest lithium ionic conductivity of 1.36 mS/cm, and the lithium symmetric battery exhibits the most stable operation.     

Tailoring solid-state synthesis routes for high confidence production of phase pure,low impedance Al-LLZO

Lithium lanthanum zirconium oxide (LLZO) garnet is a solid-state lithium ion conducting electrolyte promising all-solid-state batteries (ASSB) with high charge rates and good energy density due to its chemical stability against lithium metal anodes. LLZO has a high room temperature Li ion conductivity of ∼0.1–1 mS/cm in its cubic phase, but the stability of the cubic phase and ionic conductivity are highly sensitive to lithium stoichiometry. Stabilizing agents such as aluminum oxide and excess lithium are needed to preserve the cubic phase and compensate for lithium volatility. With the range of the end LLZO products spanning powders, porous membranes to dense membranes combined with sintering/calcination that often exceeds 1000°C, it is challenging to maintain an ideal lithium content given its high volatility from a single base powder. This study was designed to elucidate the sensitivities of aluminum doped LLZO powder synthesis and processing along its path to being utilized in a ceramic-manufacturing optimized ASSB. By utilizing thermogravimetric analysis in conjunction with in situ X-ray diffraction analysis of solid-state LLZO synthesis, it was discovered that the sensitivity of the LLZO cubic phase to lithium volatility can be reduced via early incorporation of excess lithium carbonate during initial phase formation in direct combination with controlled surface-to-volume ratios of the powders. Isostatically pressed powders of our LLZO sintered at 1100°C for 2 h showed RT ionic conductivity of 0.3–0.4 mS/cm measured via electrochemical impedance spectroscopy, and an improvement in microstructural uniformity with lowered porosity. The improved suppression of lithium volatilization has important implications for the scalable production of LLZO powders and assembly of ASSBs.     

固体电解质的制备及其在锂氧电池性能研究

本文提出了将高离子电导率的全固态电解质Li1.4Al0.4Ti1.6(PO3)4(LATP)用于锂氧电池。用Pechini法成功的合成了全固态电解质，采用X射线荧光衍射(XRD)、场发射扫描电子显微镜(SEM)和电化学性能分析其性能。结果显示，LATP不仅具有较高的离子导电性，而且LATP作为固体电解质，具有更高的放电平台。同时，LATP固体电解质能降低电解质的分解，从而能够减少放电产物的生成。因此，LATP玻璃陶瓷固体用于锂氧电池提高了锂氧电池的热稳定性并且降低了锂氧电池热膨胀。LATP固体电解质利用在可再充电锂氧电池中具有良好的前景。     

Li+电池固态聚合物电解质研究进展

固态聚合物电解质具有高安全性、高成膜性和黏弹性等优点，并与电极具有良好的接触性和相容性，是实现高安全性和高能量密度固态Li⁺电池的重要电解质体系。然而聚合物电解质室温离子电导率较低（10^-8~10^-6 S·cm^-1），不能满足固态聚合物电池在常温运行的需求。因此，在提高离子电导率、机械强度和电化学稳定性等本征属性的基础上，同时探究改善电解质/电极的界面处及电极内部的离子输运是研发固态聚合物Li⁺电池面临的关键问题。主要从改性聚合物电解质用以提高Li⁺电池电化学性能的角度出发，综述了凝胶聚合物电解质、全固态聚合物电解质和复合固态电解质中的离子输运机制及其关键参数，总结了近年来聚合物电解质的最新研究进展和未来的发展方向。     

A panoramic view of Li7P3S11 solid electrolytes synthesis,structural aspects and practical challenges for all-solid-state lithium batteries

The development of an inorganic electrochemical stable solid-state electrolyte is essentially responsible for future state-of-the-art all-solid-state lithium batteries (ASSLBs). Because of their advantages in safety, working temperature, high energy density, and packaging, ASSLBs can develop an ideal energy storage system for modern electric vehicles (EVs). A solid electrolyte (SE) model must have an economical synthesis approach, exhibit electrochemical and chemical stability, high ionic conductivity, and low interfacial resistance. Owing to its highest conductivity of 17 mS·cm^-1, and deformability, the sulfide-based Li₇P₃S₁₁ solid electrolyte is a promising contender for the high-performance bulk type of ASSLBs. Herein, we present a current glimpse of the progress of synthetic procedures, structural aspects, and ionic conductivity improvement strategies. Structural elucidation and mechanistic approaches have been extensively discussed by using various characterization techniques. The chemical stability of Li₇P₃S₁₁ could be enhanced via oxide doping, and hard and soft acid/base (HSAB) concepts are also discussed. The issues to be undertaken for designing the ideal solid electrolytes, interfacial challenges, and high energy density have been discoursed. This review aims to provide a bird's eye view of the recent development of Li₇P₃S₁₁-based solid-state electrolyte applications and explore the strategies for designing new solid electrolytes with a target-oriented approach to enhance the efficiency of high energy density all-solid-state lithium batteries.     

湿化学法制备石榴石型固态电解质Li7La3Zr2O12

锂电池因能量密度高、循环寿命长、绿色清洁等特点被广泛应用,但其液态电解质易泄漏、挥发,且隔膜易被锂枝晶刺穿造成短路,引发危险。固态电解质大多是不具燃烧性的无机材料,室温下离子电导率较高、电化学窗口宽且适用温度范围广。因此,采用固态电解质替代液态电解质具有十分重要的意义。相对于其他类型固态电解质,石榴石型氧化物Li₇La₃Zr₂O₁₂（LLZO）具有离子电导率高、电化学窗口宽（>5V vs. Li/Li⁺）、对锂稳定性好和热稳定性高等特点,是非常具有发展潜力的无机固态电解质。本文采用溶胶-凝胶法和低温燃烧法两种湿化学法合成LLZO粉末,对应的电解质片在40℃时的离子电导率分别为1.22×10^-5S/cm和3.87×10^-6S/cm,活化能分别为0.34eV和0.32eV。从实验结果综合比较,溶胶-凝胶法为最佳制备方法。     

全固态锂电池热安全性研究进展

随着液态锂电池的广泛应用,热失控现象时有发生,其热安全性成为亟待解决的问题。全固态锂电池以其优异的安全性显示出巨大的应用潜力。该文简要介绍了全固态锂电池的基本概念及组成结构,重点阐述了氧化物、硫化物以及聚合物固体电解质的最新研究进展,并对这3类全固态锂电池的热安全性差异进行了总结,包括固体电解质材料级别、固体电解质与活性材料或锂金属负极混合时界面级别以及全电池级别的热安全性。此外,锂枝晶现象对全固态锂电池安全性的影响仍不可忽视。目前针对材料和界面级别的热安全性研究众多,但全电池级别的研究较少,且多集中在小容量电池,针对全电池级别的热安全性仍需进一步探究。最后指出了未来高安全性全固态锂电池的商业化应用应着力于解决全固态锂电池中的关键界面问题以及锂枝晶问题。     

Fabrication of all-solid-state battery using Li5La3Ta2O12 ceramic electrolyte

The chemical and electrochemical properties of Li₅La₃Ta₂O₁₂ (LLTa) solid electrolyte were extensively investigated to determine its compatibility with an all-solid-state battery. A well-sintered LLTa pellet with a garnet-like structure was obtained after sintering at 1200 °C for 24 h. Li ion conductivity of the LLTa pellet was estimated to be 1.3×10⁻⁴ S cm⁻¹. The LLTa pellet was stable when in contact with lithium metal. This indicates that Li metal anode, which is the best anode material, can be applied with the LLTa system. A full cell composed of LiCoO₂/LLTa/Li configuration was constructed, and its electrochemical properties were tested. In the resulting cyclic voltammogram, a clear redox couple of LiCoO₂ was observed, implying that the all-solid-state battery with the Li metal anode was successfully operated at room temperature. The redox peaks of the battery were still observed even after one year of storage in an Ar-filled glove-box. It can be concluded that the LLTa electrolyte is a promising candidate for the all-solid-state battery because of its relatively high Li ion conductivity and good stability when in contact with Li metal anode and LiCoO₂ cathode.     

Preparation of organic/inorganic hybrid semi-interpenetrating network polymer electrolytes based on poly(ethylene oxide-co-ethylene carbonate) for all-solid-state lithium batteries at elevated temperatures

Organic/inorganic hybrid semi-interpenetrating network (semi-IPN) polymer electrolytes (HIPEs) based on poly(ethylene oxide-co-ethylene carbonate) (PEOEC) have been developed for all-solid-state lithium battery applications. In comparison to those of poly(ethylene oxide) (PEO), salient features of the PEOEC are the amorphous nature and high dielectric constant, which provide enhanced ionic conductivity. The organic/inorganic hybrid network matrix in the HIPEs is composed of different contents of photo-cross-linked octa-functional POSS acrylate (OA-POSS) and ethoxylated trimethylolpropane triacrylate (ETPTA). The effect of OA-POSS on solid-state electrolyte properties of the HIPEs is investigated in terms of the dimensional stability, thermal behavior, and ionic conductivity. Due to the presence of the rigid and bulky POSS moiety, the HIPEs exhibit improvement in ionic conductivity along with enhanced dimensional stability. The high capacity and good cycle performance of lithium batteries with the HIPEs demonstrate feasibility of applying the HIPEs to solid-state electrolytes for all-solid-state lithium batteries that can operate at elevated temperatures.