锂金属电池发展及材料分析

随着人们对锂电池续航要求不断提高,开发新体系的锂电池成为研究的热点。锂金属电池凭借着较高的比能量,吸引着众多的关注。但是由于存在正极材料克容量和稳定性不足、固态电解质材料界面阻抗大以及锂金属负极膨胀等各方面的限制,导致目前锂金属电池距离大规模应用仍有一段距离。本文从常用的正极材料、锂金属负极材料以及固态电解质材料出发,论证分析了各个材料目前的技术进展,并评估了各个材料的发展前景。     

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。     

黏土矿物纳米材料在锂电池隔膜和固态电解质中的应用研究进展

锂离子电池已被广泛应用于便携式电子设备、电动汽车和电网等领域,深刻地影响着人们的日常生活。但是受限于其低的能量密度、安全性等问题,需开发稳定、高效的电化学存储材料。黏土矿物因其独特的纳米结构、丰富的活性位点、高的比表面积、丰富的储量和低成本等优点,在锂二次电池领域有着广阔的应用前景。本文首先介绍了黏土矿物纳米材料的分类、结构和化学组成等。然后,综述了黏土矿物纳米材料在锂二次电池隔膜和固态电解质隔膜方面的应用研究进展。最后,总结了黏土矿物在电化学储能领域的优势和不足,并展望了其未来发展趋势。     

固态金属锂负极界面研究进展

开发下一代高安全性、高能量密度电池是电动汽车、可穿戴便携电子设备与可再生能源高效利用的关键。固态金属锂电池是极有希望的下一代电池体系。本文首先综述了固态电解质与界面特性,包括固态电解质中的离子传输机理和固态电解质分类,指出金属锂电极与固态电解质之间有限的固-固界面接触是固态金属锂电池实用化的重要挑战,其界面演变特性主导了固态电池的性能表现。界面演变是机械-化学-电化学耦合的过程。其次,文章综述了电池界面失效机制与构筑策略,指出界面失效包括枝晶状沉积引发的电池短路与空穴累积、副反应导致的电化学界面脱触等,使用界面润湿剂、引入界面缓冲层或构造三维多孔骨架结构化电极等是解决界面问题的重要手段。最后,文章总结指出,固态金属锂电池仍有巨大的进步空间,先进的理论研究和表征手段为进一步认识和理解固-固界面提供了新的机遇,通过界面化学、材料科学、系统工程等领域的交叉共融,有望共同推动下一代高安全、高能量密度固态储能技术的发展。     

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。     

锂金属电池用复合固体电解质及其界面研究进展

相比于液态锂电池,固态锂金属电池由于电解质不易燃、不挥发而具有更高的安全性。此外,固态电解质能够有效抑制锂枝晶的生长,使基于高能量密度的锂金属作为负极材料成为可能。但是,固态锂金属电池存在着界面阻抗大、固体电解质/电极兼容性差、电解质离子电导率低及电化学窗口较窄等问题。因此,开发高性能的柔性固体电解质对推动固态锂金属电池的发展起着重要作用。本工作总结了固态锂金属电池中聚合物与不同类型填料复合最新研究进展及复合固体电解质匹配电极材料时存在的界面阻抗大问题与解决策略。     

机械压力对锂电池性能影响的研究进展

锂电池在充放电过程中,由于锂离子的嵌入/脱出或沉积/剥离,SEI膜持续生长及产气等副反应的发生会造成电池产生内压。压力能够通过界面作用影响锂电池的各项性能。回顾并总结了近年来压力,包括电池内压及外加压力对锂电池性能影响的研究。从压力作用下电池材料的形变、界面阻抗及金属锂负极的沉积模式及电池的循环和倍率性能的改变等角度出发,详细介绍了压力对锂电池隔膜及电解质、插层电极材料、合金电极材料及锂金属电极性能的影响及作用机理。同时对合理利用压力改善电池性能以及相关锂电池的设计策略进行展望,为从事相关研发的工作者提供一些借鉴。     

荧光聚氨酯固态锂电池电解质的制备及性能

以聚碳酸酯二元醇(PCDL)和六亚甲基二异氰酸酯(HDI)为主要原料,1,4-丁二醇(BDO)和荧光小分子二元醇N,N-二羟乙基苯胺-β-三联吡啶(TPPDA)为扩链剂,制备了一种热塑性荧光聚氨酯,其与双三氟甲烷磺酰亚胺锂(LiTFSI)共混制备了荧光聚氨酯电解质(FPU)。采用傅里叶变换红外光谱仪、荧光光谱仪、拉伸测试仪、同步热分析仪、电化学工作站和电池测试仪对制备的电解质进行了结构、光学性能、力学性能、热稳定性能和电化学性能的测试与分析。结果表明,随着膜内LiTFSI质量分数的增加,荧光强度增大;LiTFSI质量分数为30%制备的荧光聚氨酯电解质膜(FPU-3)拉伸强度达到4.5 MPa,电导率达到1.03×10~(–4) S/cm;采用LiTFSI质量分数为30%的荧光聚氨酯电解质膜与磷酸铁锂正极和锂金属负极组装的全固态电池表现出良好的倍率与循环性能,在80℃、0.2 C和1.0 C倍率下首次放电比容量分别达到164和112 mA·h/g。     

锂金属负极中人工固体电解质间相保护膜研究进展

介绍了锂电池的发展,锂金属电池的优势及面临的挑战,即锂金属电池存在循环稳定性差和枝晶生长的问题。对此,可以在锂负极表面构建一种人工固体电解质间相（SEI）保护膜。叙述了SEI保护膜的形成、研究方向和负极材料所具备的条件,讨论了锂金属负极电池发展方向,认为锂金属负极电池的需要在基础研究、材料开发和电池工程等方面付出更多的努力。     

硼氢化锂及其衍生物固态电解质研究进展

含BH4-的硼氢化物及其衍生物,具有较高的离子电导率、较宽的电位窗口、及与金属负极材料较好的兼容性等特性,是一类潜在的固态电解质材料.本文主要综述了硼氢化锂及其衍生物作为固态电解质在全固态电池方面应用的研究进展.首先,介绍了硼氢化锂及其衍生物的结构与性质;其次,阐述了该类材料在固态电解质方面的应用及改性;最后,展望了硼...     

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.     

Stable interfaces constructed by concentrated ether electrolytes to render robust lithium metal batteries

Lithium metal batteries (LMBs) are highly considered as promising candidates for next-generation energy storage systems.However,routine electrolytes cannot tolerate the high potential at cathodes and low potential at anodes simultaneously,leading to severe interfacial reactions.Herein,a highly concentrated electrolyte (HCE) region trapped in porous carbon coating layer is adopted to form a stable and highly conductive solid electrolyte interphase (SEI) on Li metal surface.The protected Li metal anode can poten-tially match the high-voltage cathode in ester electrolytes.Synergistically,this ingenious design promises high-voltage-resistant interfaces at cathodes and stable SEI with abundance of inorganic components at anodes simultaneously in high-voltage LMBs.The feasibility of this interface-regulation strategy is demonstrated in Li | LiFePO4 batteries,realizing a lifespan twice as long as the routine cells,with a huge capacity retention enhancement from 46.4％ to 88.7％ after 100 cycles.This contribution proof-of-concepts the emerging principles on the formation and regulation of stable electrode/electrolyte inter-faces in the cathode and anode simultaneously towards the next-generation high-energy-density batteries.     

二次电池中金属锂负极沉脱机理研究进展

金属锂负极是下一代高比能二次电池备受关注的负极材料,以金属锂为负极的锂金属电池具备极高的理论能量密度,但其仍存在充放电循环效率低、电池寿命短等问题。要实现高能量密度高安全性的锂金属电池的合理设计和优化,需要对金属锂负极中锂金属沉积脱出过程的离子输运、电子输运、界面反应等机制机理有清晰的认识。本文针对金属锂负极中存在的枝晶生长、死锂形成、固体电解质界面膜作用等机理问题,综述了研究者们在其沉脱机理的模型与理论计算、实验研究等方面做出的诸多研究进展,为锂金属电池的合理设计提供了更全面的机理认识。     

Effect of cell pressure on the electrochemical performance of all-solid-state lithium batteries with zero-excess Li metal anode

All-solid-state cells (ASSCs) typically operate at a specific pressure to ensure good contact between the solid electrolyte and the electrode-active materials. However, establishing the ideal cell pressure is challenging because of the various cell structures, the mechanical characteristics of solid electrolytes, and the extent to which the volume of the electrodes changes during cycling. In this study, we propose a specially designed cell assembly that adjusts to the changes in volume that occur during cycling while maintaining a constant cell pressure. The evaluations indicate that the spring in the cell assembly effectively reduces the stress incurred from the volume expansion that occurs in the electrode during charging (lithiation) and the volume contraction that occurs during discharging (delithiation) while maintaining the prescribed cell pressure. The capacity fading—as a function of the cycle number—decreases when operating ASSCs comprising a cell assembly that include a spring, compared with those that exclude a spring. Focused ion beam–scanning electron microscope reveals no cracks and delamination in the LiNi_0.8Co_0.1Mn_0.1O₃ (NCM811) composite cathode of the ASSCs, operated at 25 MPa, with a spring-equipped assembly. The Ag nanolayer that deposits on the Cu foil is an effective collector metal, forming a dense lithium plating layer on the Ag/Cu foil anode.     

全固态锂离子电池的研究进展与挑战

全固态锂离子电池具有安全性高、电化学性能优异等优点,但存在电极与电解质界面相容性差、室温离子电导率低等问题。本文总结了以上问题产生的原因及解决方案。对于正极界面,可复合正极材料与固态电解质、构造三维多孔结构固态电解质或在界面处引入缓冲层。对于负极界面,可设计界面层、原位聚合生成固态电解质、构造固态电解质骨架或使用自愈合和弹性固态电解质。对于固态电解质自身,以聚氧化乙烯（PEO）固态聚合物电解质为例,可添加增塑剂、无机陶瓷填料或构造聚合物共混物与嵌段共聚物。最后,对今后的研究方向提出了建议：应注重优化电极/固态电解质界面层;探索锂离子传输机理;构建具有高离子电导率的固态电解质等。     

The function of vinylene carbonate as a thermal additive to electrolyte in lithium batteries

The role of vinylene carbonate (VC) as a thermal additive to electrolytes in lithium ion batteries is studied in two aspects: the protection of liquid electrolyte species and the thermal stability of the solid electrolyte interphase (SEI) formed from VC on graphite electrodes at elevated temperatures. The nuclear magnetic resonance (NMR) spectra indicate that VC can not protect LiPF₆ salt from thermal decomposition. However, the function of VC on SEI can be observed via impedance and electron spectroscopy for chemical analysis (ESCA). These results clearly show VC-induced SEI comprises polymeric species and is sufficiently stable to resist thermal damage. It has been confirmed that VC can suppress the formation of resistive LiF, and thus reduce the interfacial resistance.     

Morphology and electrochemical and mechanical properties of polyethylene‐oxide‐based nanofibrous electrolytes applicable in lithium ion batteries

We report the synthesis of all‐solid‐state polymeric electrolytes based on electrospun nanofibers. These nanofibers are composed of polyethylene oxide (PEO) as the matrix, lithium perchlorate (LiClO₄) as the lithium salt and propylene carbonate (PC) as the plasticizer. The effects of the PEO, LiClO₄ and PC ratios on the morphological, mechanical and electrochemical characteristics were investigated using the response surface method (RSM) and analysis of variance test. The prepared nanofibrous electrolytes were characterized using SEM, Fourier transform infrared, XRD and DSC analyses. Conductivity measurements and tensile tests were conducted on the prepared electrolytes. The results show that the average diameter of the nanofibers decreased on reduction of the PEO concentration and addition of PC and LiClO₄. Fourier transport infrared analysis confirmed the complexation between PEO and the additives. The highest conductivity was 0.05 mS cm^?1 at room temperature for the nanofibrous electrolyte with the lowest PEO concentration and the highest ratio of LiClO₄. The optimum nanofibrous electrolyte showed stable cycling over 30 cycles. The conductivity of a polymer film electrolyte was 29 times lower than that of the prepared nanofibrous electrolyte with similar chemical composition. Furthermore, significant fading in mechanical properties was observed on addition of the PC plasticizer. The results obtained imply that further optimization might lead to practical uses of nanofibrous electrolytes in lithium ion batteries. © 2019 Society of Chemical Industry