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。     

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。     

全固态锂离子电池硫化物电解质的研究进展

目前,锂离子电池已经广泛地应用于交通、通讯、便携式电子产品及电动工具等领域。传统的锂离子电池采用液体电解液,存在易挥发、易泄漏、抗冲击性能差等缺点,存在安全隐患。全固态电解质具有热稳定性高、循环寿命长、抗震动性能好等优点,是锂离子电池取代液体电解液的一种理想替代方案。硫化物电解质体系具有离子导电率高、制备简便、电化学窗口宽等优点,已经成为全固态锂离子电池的研究热点。综述了全固态锂电池Li₂S-P₂S₅基电解质的最新研究进展,总结了各种性能改进方法,并对其应用前景做了展望。     

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。     

固态无机电解质Li7La3Zr2O12的改性研究进展

作为一种固态无机电解质材料,石榴石型立方相Li₇La₃Zr₂O₁₂具有较高的室温锂离子电导率、较宽的电化学窗口和优良的热稳定性等特点,是高安全性、高能量密度固态锂离子电池实现商业化应用的关键。阐述了Li₇La₃Zr₂O₁₂的晶体结构与锂传导机理,综述了元素掺杂、聚合物电解质复合、烧结助剂引入、表面包覆或修饰等方式对Li₇La₃Zr₂O₁₂的物相结构稳定性、界面阻抗与相容性、烧结活性、离子电导率等进行改性的最新研究进展。最后,针对Li₇La₃Zr₂O₁₂在产业化应用中所面临的障碍与挑战,提出了制备新工艺的开发、离子电导率的多重改性以及柔性复合电解质膜的结构设计与优化等应对策略,为推动高性能固态锂离子电池的发展提供依据。     

石榴石型固体电解质体系：离子输运性能调控及其全固态电池研究进展

全固态锂电池采用固体电解质取代液态电解质，使其具有更高安全性，且有望进 一步提高电池的能量密度。而在众多固体电解质中，具有石榴石型结构的立方相 Li7La3Zr2O12 (LLZO) 及其元素掺杂产物由于室温离子电导率较高、电化学窗口较宽、与锂金属稳定等优点， 最有可能应用于全固态锂电池中。本文对 LLZO 的物相及晶体结构、制备方法、锂离子电导率 的提升策略以及其所组装的全固态锂电池等方面进行了详细介绍，并预测了 LLZO 固体电解质 材料进一步提升锂离子电导率的潜在可能以及 LLZO 所装配的全固态锂电池的发展方向。     

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。     

Enhanced electrochemical performance of garnet-based solid-state lithium metal battery with modified anodic and cathodic interfaces

Due to high ionic conductivity and wide electrochemical window, the garnet solid electrolyte is considered as the most promising candidate electrolyte for solid-state lithium metal batteries. However, the high contact impedance between metallic lithium and the garnet solid electrolyte surface seriously hampers its further application. In this work, a Li-(ZnO)_x anode is prepared by the reaction of zinc oxide with metallic lithium and in situ coated on the surface of Li_6.8La₃Zr_1.8Ta_0.2O₁₂(LLZTO). The anode can be perfectly bound to the surface of LLZTO solid electrolyte, and the anode/electrolyte interfacial resistance was reduced from 2319 to 33.75 Ω·cm². The Li-(ZnO)_0.15|LLZTO|Li-(ZnO)_0.15 symmetric battery exhibits a stable Li striping/plating process during charge-discharging at a constant current density of 0.1 mA·cm^-2 for 100 h at room temperature. Moreover, a Li-(ZnO)_0.15|LLZTO-SPE|LFP full battery, comprised of a polyethylene oxide-based solid polymer electrolyte (SPE) film as an interlayer between LiFePO₄ (LFP) cathode and LLZTO solid electrolyte, presents an excellent performance at 60 ℃. The discharge capacity of the full battery reaches 140 mA·h·g^-1 at 0.1 C and the capacity attenuation is less than 3% after 50 cycles.     

短链多硫化物在离子液体中聚集行为的分子动力学模拟

离子液体因其优异的物化性质、能抑制多硫化物溶解等特点,近年来被广泛应用于锂硫电池电解液中。在电池充放电产物中,难溶性Li₂S和Li₂S₂易聚集沉积在电极表面,影响电池性能,而目前关于其团聚行为与电解液性质的微观机理研究较少。本工作利用量化计算和分子动力学模拟分析了短链Li₂S和Li₂S₂在离子液体中的微观结构以及形成团簇的情况。通过分析体系的微观结构发现,阳离子中主要与S作用的是侧链甲基,短链多硫化物之间Li-S作用远强于与阴离子的Li-O作用。团簇尺寸分布的结果表明,短链多硫化物在[TFSI]型离子液体中易形成多分子的大团簇,Li₂S₂体系比Li₂S体系中的大团簇比例更高;离子液体阴离子配位能力越强,形成大的Li₂S团簇比例越少,但阴离子的构型特点和作用形式也会对团簇的尺寸结构造成影响。     

固态金属锂电池研究进展：外部压力和内部应力的影响

固态锂金属电池具有理论能量密度高、安全性高等优势,是极有前景的下一代储能系统。然而,固体电极与固体电解质之间有限的固–固接触严重阻碍了界面离子的传输。因此,增加外部压力是增加固–固接触及延长电池循环寿命的重要途径。同时,在充放电过程中,电极体积变化产生的内应力也将影响电池界面特性。通过介绍两种基本物理接触模型,结合硫化物、氧化物、聚合物电解质以及金属锂的物理性质,综述了外压和内部应力对电解质、电极及电池的影响。最后,对外压力与内应力在全固态金属锂电池中的作用进行了总结和展望。     

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.     

Composite polymer electrolyte incorporating WO3 nanofillers with enhanced performance for dendrite-free solid-state lithium battery

All solid-state lithium batteries (ASS-LBs) with polymer-based solid electrolytes are a prospective contender for the next-generation batteries because of their high energy density, flexibility, and safety. Among all-polymer electrolytes, PEO-based solid polymer electrolytes received huge consideration as they can dissolve various Li salts. However, the development of an ideal PEO-based solid polymer electrolyte is hindered by its insufficient tensile strength and lower ionic conductivity due to its semi-crystalline and soft chain structure. In order to lower the crystallization and improve the performance of PEO-based solid polymer electrolyte, tungsten trioxide (WO₃) nanofillers were introduced into PEO matrix. Herein, a PEO₂₀/LiTFSI/x-WO₃ (PELI-xW) (x = 0%, 2.5%, 5%, 10%) solid composite polymer electrolyte was prepared by the tape casting method. The solid composite polymer electrolyte containing 5 wt% WO₃ nanofillers achieved the highest ionic conductivity of 7.4 × 10^-4 S cm^-1 at 60 °C. It also confirms a higher Li-ion transference number of 0.42, good electrochemical stability of 4.3V, and higher tensile strength than a PEO/LiTFSI (PELI-0W) fillers-free electrolyte. Meanwhile, the LiFePO₄│PELI-xW│Li ASS-LBs demonstrated high performance and cyclability. Based on these findings, it can be considered a feasible strategy for the construction of efficient and flexible PEO-based solid polymer electrolytes for next-generation solid-state batteries.     

聚合物基镁离子固态电解质的研究进展Q

镁离子电池因其比容量高、资源丰富、环境友好、安全性高(无枝晶)等优势,在储能电池领域脱颖而出.然而,镁金属负极在液态电解质中易钝化,导致其电化学性能不佳.因此,开发高效适用的固态电解质对实现高性能、实用化镁离子电池至关重要.聚合物电解质具有优异的机械稳定性、电化学稳定性、热稳定性且离子电导率高、成本低.但镁离子较高的电荷密度和较强的溶剂化作用限制了其在固态电解质中的解离与扩散.从纯固态聚合物电解质、凝胶聚合物电解质、复合聚合物电解质3个方面综述了国内外聚合物基镁离子固态电解质的离子电导率对解决镁金属负极钝化效应的贡献及其应用研究进展,指出聚合物基镁离子固态电解质当前面临的挑战并对其研究方向进行了建议和展望.     

Recent progress on garnet-type oxide electrolytes for all-solid-state lithium-ion batteries

Currently, the safety of lithium-ion batteries has attracted much attention. All-solid-state batteries (ASSBs) are promising replacements for liquid-electrolyte lithium-ion batteries due to their high energy density and excellent safety. The choice of electrolyte is the most critical part of ASSBs. Li₇La₃Zr₂O₁₂ (LLZO)-based solid-state electrolytes (SSEs) render high energy density, wide electrochemical window and high lithium-ion mobility. However, their low lithium-ion conductivity compared with liquid organic electrolytes and rigid interfacial contact at electrode/electrolyte interface mainly hinder the development of LLZO-based ASSBs. Herein, we review recent progress in the area of LLZO-based SSEs by discussing the structure and transport mechanism of lithium (Li)-ions of LLZO. Also, we summarize bottleneck problems and corresponding solutions, providing theoretical basis and technical support for the development of LLZO-based ASSBs. Finally, future prospects of LLZO-based ASSBs are discussed in next-generation energy storage systems.     

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。     

High performance NASICON ceramic electrolytes produced by tape-casting and low temperature hot-pressing: Towards sustainable all-solid-state sodium batteries operating at room temperature

In this work, we propose a processing methodology, based on the combination of tape-casting and low temperature hot-pressing, to develop ceramic NASICON electrolytes with formula Na_3.16Zr_1.84Y_0.16Si₂PO₁₂ towards the attainment of solid-state sodium batteries operating at room temperature. Solid-state NASICON electrolytes with very good mechanical properties and high ionic conductivity are successfully tested in terms of electrochemical behavior by using the cell configuration: Na/NASICON/FePO₄. Following charge-discharge cycles, an unusual redox pair of FePO₄ is found, indicating that the all-solid-state battery with the Na metal anode may be effectively operated at room temperature. At a charge/discharge current density of C/20, the solid-state battery has an initial reversible discharge capacity of 85 mAh/g. Because of its relatively high ionic conductivity and thermostability, when in contact with the Na anode and the FePO₄ cathode, the NASICON ceramic electrolyte is a viable option for attaining reliable, safer and sustainable all-solid-state batteries operating at room temperature.     

Effect of sintering and annealing on electrochemical and mechanical characteristics of Na3Zr2Si2PO12 solid electrolyte

NASICON (Sodium superionic conductor) type Na₃Zr₂Si₂PO₁₂ (NZSP) has received a lot of interest as the solid electrolyte for all-solid-state sodium-ion batteries (ASSIBs). The electrolyte has superior interfacial characteristics, high thermal stability, and good ionic conductivity. Because of their higher energy density, improved mechanical stability, no liquid leakage problem, and higher operating voltages, All solid-state batteries are expected to replace liquid electrolyte-based batteries in many applications. The solid electrolyte also acts as a separator, and hence additional separator is not required for cell operations. Because of its 3D open architecture and continuous diffusion channels, NZSP is considered a better solid electrolyte. The NZSP solid electrolyte has been synthesized by spark plasma sintering (SPS) followed by annealing the sintered materials. The SPS method leads the material to have higher density and ionic conductivity. Conventional sintering of the materials requires a temperature as high as 1225°C; however, the temperature required for the SPS is as low as 1050°C. Moreover, conventional sintering yields samples of relative density up to 91%, while SPSed samples have achieved a maximum density of around 98%. The ionic conductivity of solid electrolyte SPSed at 1050°C for 10 min is found to be 3.5 × 10⁻⁴ S/cm with an activation energy of 0.27 eV. The annealing of the SPSed samples improves the ionic conductivity of the SPS1050-20mins sample to roughly double the value obtained from the as-prepared SPS sample because there are fewer secondary phases and a structural change from a rhombohedral to a monoclinic system. To ascertain the samples' crystal structure, particle shape, and ionic conductivity, materials were characterized using X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy. The samples' mechanical characteristics, for example, the hardness and fracture toughness of the samples, were also determined.     

Improving room-temperature electrochemical performance of solid-state lithium battery by using electrospun La2Zr2O7 fibers-filled composite solid electrolyte

Low ionic conductivity at room temperature and poor interfacial compatibility are the main obstacles to restrain the practical application of polymer solid electrolytes. In this work, lanthanum zirconate (LZO) fibers were prepared by electrospinning method and used for the first time as fillers in sandwich polypropylene carbonate (PPC)-based solid electrolyte. Meanwhile, a graphite coating was applied on one surface of the composite solid electrolyte (CSE) membrane. The results show that the LZO fibers significantly increases the room-temperature electrochemical performance of the CSE, and the graphite coating enhances the interfacial compatibility between electrolyte and lithium anode. Furthermore, an ultra-thin PPC-LZO CSE with a total thickness of 22 μm was prepared and used in NCM622/CSE/Li solid-state cell, which shows an initial discharge capacity of 165.6 mAh/g at the current density of 0.5C and a remaining capacity of 113.0 mAh/g after 250 cycles at room temperature. Rise to 1C, the cell shows an initial discharge capacity of 154.2 mAh/g with a remaining capacity of 95.6 mAh/g after 250 cycles. This ultra-thin CSE is expected to be widely applied in high energy-density solid-state battery with excellent room-temperature electrochemical performances.     

新能源汽车固态电池中的锂枝晶抑制研究

相比于商业化的锂离子电池,固态电池具有更高的能量密度和更好的安全性。然而,固体电解质依旧面临锂枝晶生长的问题。以目前已大规模工业化的聚氧化乙烯（PEO）基电解质作为研究对象,通过将PEO与高杨氏模量的石榴石型电解质复合,抑制了锂枝晶在PEO基复合电解质中的生长,不仅使电解质膜的离子电导率从9.8×10^-6 S/cm增加到了3.8×10^-4 S/cm,还使锂/锂对称电池的临界电流密度从0.4 mA/cm²提高到1.6 mA/cm²。与此同时,组装的基于金属锂负极与传统石墨负极的软包电池可分别获得334.5 W·h/kg与218.2 W·h/kg的能量密度。其中,钴酸锂/复合电解质/石墨软包全电池循环1 000次后的容量保持率可达92.3%,能够满足新能源汽车的需求。     

Lithium Thiophosphate Glasses and Glass–Ceramics as Solid Electrolytes: Processing,Microstructure, and Properties

Lithium solid electrolytes are of major interest for solid-state batteries and electrochemical capacitors (ECs). Currently, the material selection space of liquid electrolytes is dominated by lithium salts paired with organics. Improved safety, as well as the need for higher temperature and high voltage operation, opens up opportunities for glass and ceramic alternatives in these important solid-state energy storage technologies. Lithium thiophosphates in the family x Li₂S + (1−x) P₂S₅ (mol fraction) possess room temperature ionic conductivities greater than 10⁻³(Ω-cm)^-1 in crystallized x = 0.70 (almost the highest in inorganic solid-state electrolytes). Within this review article, we address recent progress made in this class of material. We consider the role of densification on the Li-ion conductivity, as well as our recent data on the effect of densification on the electrochemical properties of the system. We cover the processing techniques of mechanical milling and pressure-forming, discuss microstructure, bulk versus surface conduction, and device integration. The systematic improvement in ionic conductivity with increased density suggests that bulk conduction dominates surface conduction and demonstrates that dense, rather than porous, lithium thiophosphate solid electrolytes are important in the design of solid-state batteries and ECs.