关键词： 固态锂电池   复合电解质   黏土矿物   锂负极  

摘要： 研发高离子电导率、高电化学和热稳定性、高界面兼容性等综合性能优异的固态电解质是固态锂电池发展的关键。当前流行的聚合物、氧化物、硫化物等固态电解质虽各有优点但综合性能存在短板,将聚合物电解质与硫化物和氧化物电解质复合是提升固态电解质综合性能的有效策略。但是,氧化物和硫化物固态电解质材料普遍获取成本较高,制备工艺较为复杂。黏土矿物获取容易、成本低廉、对环境无害,而且黏土矿物往往具有特殊的二维层状结构和带电性质。因此,本论文选用应用潜力更大的黏土矿物与PEO（聚环氧乙烷）、PVDF（聚偏氟乙烯）等常见聚合物基体复合,以制备综合性能较为均衡的固态复合电解质。论文取得的主要成果如下: （1）以离子液体（IL）和锂化锂皂石（LLZS）为填料与PEO、LiTFSI复合,制备了粘弹性复合聚合物电解质。该复合电解质离子电导率达3.29×10-4 S cm-1,电化学稳定窗口达5 V以上。将PEO-Li-IL-LLZS组装于NCM811//Li固态电池进行测试,发现该电池在室温环境、0.1 C倍率下的放电比容量为理论值(190 mAh g-1)的97.5%,达185.2 mAh g-1;但是该电池循环性能不佳,在0.3 C倍率下循环120圈后容量衰减为107 mAh g-1。 （2）以锂化蒙脱石（MMTli）为填料,以PEO、LiTFSI（双三氟甲磺酰亚胺锂）为主体材料,通过溶液刮涂法首次制备了具有“花朵状”球晶形貌的PEO基全固态复合电解质,其室温离子电导率可达1.47×10-4 S cm-1,t Li+可达0.62,电化学稳定窗口为4.99 V。将该复合电解质（10%-Hs）组装为LiFe PO4|10%-Hs|Li电池,发现该电池在1 C倍率时的可逆容量达到109 mAh g-1,而且该电池可在0.2 C倍率下稳定循环200次,其容量保持率为82%。 （3）以PEO和埃洛石纳米管（HNT）为填料,通过溶液刮涂法制备了一种PVDF基复合电解质。结果表明,粘弹性PEO与刚性的HNT协同作用,可使PVDF基复合电解质获得高室温离子电导率(2.45×10-4 S cm-1)、高锂离子迁移数(t Li+=0.67)、宽电压窗口（5.02V）、高力学性能（抗拉强度>12 MPa,应变>56%）和较好的阻燃性。 （4）以MMTli、PVDF和LiTFSI为原料,通过溶液浇筑结合热压法制备了PVDF插层的高蒙脱石含量复合电解质,其室温离子电导率高达2.28×10-4 S cm-1,电化学稳定窗口达4.8 V,t Li+达0.57,断裂强度达12.58 MPa。此外,该复合电解质表现出优异的热稳定性,难以被点燃。同时,LiFPO4|SPE-0.5Li|Li固态电池表现出较好的循环性能,在25℃、0.5 C下循环100圈后仍保持130 mAh g-1的放电比容量。

关键词： 固态锂电池   固态电解质   高电压正极   表面包覆  

摘要： 采用锂金属负极的可充电固态电池由于高能量密度和高安全而受到广泛关注。固态电解质作为固态锂电池的关键材料,对固态电池的能量密度、循环性能和安全性有重要影响。聚合物电解质因其重量轻、成本低、高柔韧性等优点而广泛应用。然而,聚合物电解质的商业化却受到聚合物自身或者聚合物基电解质的电化学窗口较窄、难以与高电压正极匹配的影响。以往研究表明,通过采取正极材料的表面包覆,减少聚合物电解质与高电压正极之间的接触,是提高固态锂电池能量密度的有效策略。本文系统研究了环化聚丙烯腈聚合物包覆的正极材料,并进一步在电极电解质层之间引入离子液体,实现固态锂电池的性能提升,主要研究内容和结果如下:（1）将具有电子转移能力的环化聚丙烯腈（Cyclized polyacrylonitrile,c PAN）纳米颗粒包覆在钴酸锂（LCO）颗粒（LCO@c PAN）上。构筑了以LCO@c PAN为正极,聚偏氟乙烯-六氟丙烯（Poly vinylidenefluoride-hexafluoro propylene,PVDF-HFP）为固态电解质,锂金属为负极的LCO@c PAN/PVDF-HFP/Li固态电池,并在正极与PVDF-HFP电解质之间引入N-甲基-N-丙基哌啶双（三氟甲基磺酰）酰亚胺(N-methyl-N-propylpiperidine bis（trifluoromethylsulfonyl）imide,PP13-TFSI)基离子液体（IL）。电子导电的c PAN与离子导电的离子液体匹配,实现了正极内部离子电子复合导电网络的构筑及正极/PVDF-HFP界面处的致密接触。在30°C、0.1C、截止电压4.2 V的条件下,所构筑的固态锂电池表现出125.2 m Ah g-1,100次循环后容量保持率为87.7%。（2）将cPAN包覆在LiNi0.6Co0.2Mn0.2O2（NCM622）颗粒（NCM@c PAN）上,构筑了以NCM@c PAN为正极,聚氧化乙烯（polyethylene oxide,PEO）为固态电解质,锂金属为负极的NCM@c PAN/PEO/Li固态电池,并在正极与PEO电解质之间引入PP13-TFSI离子液体。c PAN包覆层与离子液体共同作用,减少了高电压NCM正极与PEO电解质的直接接触,且在电池循环过程中形成了由氟化锂和氮化锂组成的刚性正极侧离子导电中间相（CEI）,进一步增强PEO对高电压正极的稳定性。结果表明,在50℃、0.1C、截止电压4.2、4.25和4.3 V的条件下,基于PEO电解质的NCM@c PAN/PEO/Li固态电池,循环性能均得到提升,100次循环后高于80%的容量保持率。且在正极载量提高至6.2 mg cm-2时,在循环50圈后,仍具有86.2%的容量保持率。以上研究结果表明,通过包覆的方法可以有效将聚合物电解质与高电压正极分隔,避免聚合物电解质的氧化分解,提高聚合物电解质对高电压正极的稳定性。另外,高离子电导率的离子液体可用来改善电极与固态电解质间的固固接触,实现界面处离子的快速传输。将正极包覆与离子液体修饰结合,可实现电池循环性能的提升,为高能量密度的聚合物基固态锂电池制备提供方案。

关键词： 固态锂离子电池   复合固态电解质   PVDF-HFP   LLZTO   宽温性能  

摘要： 固态电解质作为固态锂离子电池的重要组成之一,其性能的好坏决定了固态电池是否能良好发挥其优势。目前商用的主要是液态锂离子电池,但是液态锂离子电池的安全性与能量密度瓶颈等问题制约了其可持续性发展。固态电解质因其良好的安全性能以及对金属锂的良好适应性而受到广泛关注,使用固态电解质构筑的固态锂离子电池有望解决上述问题,这使得广大研究者的目光转向了如何研发制备出更为安全和能量密度更高的固态锂离子电池。但是,随着固态电解质的引入也带来了一系列的挑战,如固态锂离子电池的宽温性能问题以及固态电解质与高电压正极之间的适配性问题等。本文主要研究的是复合固态电解质。石榴石型锂镧锆钽氧(LiLaZrTaO,LLZTO)因其良好电化学稳定性以及高室温离子电导率而成为最具代表性的无机固态电解质之一。聚偏氟乙烯-六氟丙烯(poly(vinylidene fluoride-hexafluoropropylene,PVDF-HFP)的离子电导率相对较高,结晶度较低,也成为了近年来的研究热点。本文以PVDF-HFP作为主要基底,将LLZTO作为主要的无机填料,进行实验研究。(1)以PVDF-HFP为聚合物基体,LLZTO和锂盐Li Cl O作为填充,使用溶液浇铸法制备PVDF-HFP-Li Cl O-LLZTO复合固态电解质。该电解质具有PVDF-HFP聚合物电解质的柔软坚韧而具有自支撑性,以及无机固态电解质LLZTO的良好机械性能。引入LLZTO,除了可以提高固体电解质的机械强度,还可以打乱PVDF-HFP的侧链,降低聚合物的结晶度。此外,Li Cl O因其高电化学和热稳定性、良好的可溶性和促进形成稳定的SEI而被广泛应用于固体电解质中。此外,Li Cl O中的Li和Cl O可以打断聚合物骨架的堆积,促进链段的运动,从而降低聚合物的结晶度,提高离子传导性。两者的协同作用制备的电解质组装的Li/电解质/Li对称电池,在30和60℃和0.1 m A cm和0.2 m A cm各循环100小时后,复合固体电解质电池在所有给定电流密度下都表现出稳定的镀锂/剥离过程,表现出非常稳定的极化电压。以该固态电解质与磷酸铁锂(Li Fe PO,LFP)构筑的固态电池在30和60℃时的初始放电比容量分别为133.3和167.2 m Ah g。循环150次后,放电比容量仍可保持在98.6和122.1 m Ah g。(2)以PVDF-HFP/聚砜醚(Poly(ether sulfones),PES)作为双聚合物基底,同样以LLZTO和锂盐Li Cl O作为填充。无定形相的HFP基团,扩大了聚合物基体的非晶域,以及降低了其玻璃化转变温度。PES具有较高的温室电导率、机械强度和阻燃性。以此作为双聚合物基底所制备的双基质复合固态电解质,在60℃具有更高的离子电导率5.97×10S cm,和更高的锂离子迁移数0.66。以此为电解质构建成的固态电池体系在进行充放电循环300次后进行XPS测试,测试表明形成的富Li F的SEI,表明该电解质可以抑制枝晶的沉积,提高了电池的安全性。将固态电池在20～60℃进行电化学性能测试,固态电池在0.2C,30和60℃下循环150次之后,其容量保持率分别75.6和86.4%。(3)对双基质复合固态电解质进行改性,加非活性物质Li F。Li F作为非活性添加剂可以提高电解质在高截止电压下的电化学稳定性,改善阴极和电解质的高压兼容性,从而形成稳定的阴极/电解质界面。所制备的电解质的电化学窗口为5 V,较未改性前的有了一定提升。表明Li F的加入可以提高电解质的电化学窗口。并制备钛酸锂(LiTiO,LTO)、LFP和钴酸锂(Li Co O,LCO)正极,分别与该固态电解质组装成电池并进行电化学性能测试。测试结果表明,LFP固态电池有优异的倍率性能,电池在初始0.1C时的放电比容量139.59 m Ah g,经过0.2、0.3、0.5和1C再恢复到0.1C的139.58 m Ah g,有良好的可逆性能。此外,因其较宽的电化学窗口,不同电压正极与该电解质组装而成的固态电池均有良好的电化学性能,因此该电解质与正极之间有较好的适配性。

关键词： 全固态锂电池   聚合物电解质   电化学窗口   多层聚合物电解质  

摘要： 目前锂离子电池的关键挑战是如何提高电池的能量密度和电池的安全性,使用固态电解质的固态锂电池可以有效地缓解这两个问题。固态电解质是固态电池发展的关键材料。固态聚合物电解质(solid-statepolymer electrolyte,SPE)具有较高的柔韧性、优良的加工性和良好的界面接触性,是固态锂金属电池理想的电解质材料。SPE的离子导电性、电化学窗口以及与电极之间界面的稳定性对固态锂电池的综合性能起着至关重要的作用。根据电化学稳定窗口的不同,本文主要综述了:①低电压稳定SPE,与锂金属具有良好的相容性,通过交联、共混、共聚以及与无机填料复合的方法可以有效降低其结晶度,提升聚合物离子电导率;②高电压稳定SPE体系,能够匹配高电压正极使用,有效提高锂金属电池的能量密度;③多层结构SPE体系,能够同时承受锂金属负极的还原和高电压正极的氧化,为进一步开发高性能SPE和提高电池能量密度提供了新思路。最后,对三种SPE体系进行了总结和展望,指出低电压稳定SPE的研究重点在于提高离子电导率以及力学性能,高电压稳定SPE的关键在于降低材料的最高占据分子轨道(highest occupiedmolecularorbital,HOMO)以及建立正极界面处稳定的CEI层,多层SPE的研究重点在于合适的电池和电极结构设计。构建可与正、负极同时稳定或者同时形成界面钝化层的高导离子聚合物结构是未来的研究重点之一。

关键词： 固态锂电池   聚合物电解质   能量密度   安全性  

摘要： 聚合物作为一种固态电解质具有优良的力学和机械性能,它的性质很大程度上决定了固态锂电池的电化学性能。对部分近期比较热门的聚合物电解质的研究进展进行简要总结,将不同聚合物电解质的性能和优缺点进行比较和讨论,并且对聚合物电解质的研究发展进行展望。

关键词： Urethane linkage   Crosslinker   Solid polymer electrolyte   Lithiophilicity   Lithium batteries  

摘要： All-solid-state polymer electrolytes (SPEs) are key for improving lithium-ion battery (LIB) safety and the practical application of metallic Li anodes. The major challenges of developing SPEs are their ionic conductivity, interfacial affinity, and flammability. In this article, synthesis of an SPE comprising lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and poly(ethylene oxide) networked with an acylamino-functionalized crosslinker is reported. The acylamino sites, urethane and biuret linkages, dissociate LiTFSI and may form deepeutectic-solvent domains to facilitate ion transport. This SPE is fire-retarding because CO2 evolves when the urethane decomposes at high temperatures. When operated at room temperature, the all-solid-state Li|SPE| LiFePO4 cell exhibits a high rate capability and long lifespan. Due to the high elasticity of the SPE, the polymers can self-rearrange during operation to reduce the Li-SPE interfacial resistance and regulate Li+-ion transport for uniform Li deposition. The rearrangement may involve migration of the low-energy alkane chains in the crosslinker toward the Li-anode, resulting in overspreading of lithiophilic carbonyl groups and F-atoms of TFSIat the interface. This rearrangement property enables the SPE to act as an artificial interlayer in liquid-electrolyte LIBs. The advantages of using an acylamino-functionalized crosslinker to synthesize a networked SPE for high ionic conductivity and interfacial compatibility are demonstrated.

关键词： Solid-state polymer electrolyte   Self-healing   Polymerized ionic liquid   Multi-arm   Flexible lithium battery  

摘要： Solid-state polymer electrolytes (SPEs) with outstanding flexibility and self-healing capacity are appealing for utilization in reliable and wearable electronic devices. Herein, a highly stretchable (extensibility 2 h, 25 celcius). Moreover, DPIL-6-SPE presents a superior adhesion strength (weight loading 200 g) towards lithium electrode, signifying excellent interfacial compatibility. Compared with the counterpart of monocationic polymeric ionic liquid derived SPE (MPIL-6-SPE), the multiple cationic center in DPIL-6-SPE facilitates the dissociation of lithium salt and liberates more Li+ from trapping with TFSI-, thereby resulting in a superior ionic conductivity (over 10(-5) S cm(-1) at room temperature) and lithium ion transference number (0.46). The as-assembled LiFePOoPIL-6-SPE/Li battery can deliver a high discharge capacity of 152.6 mAh g(-1) at 0.1C, and its capacity retention rate reaches 94% after 50 cycles with a coulombic efficiency of 96%. In particular, the mechanical properties and conductivity of DPIL-6-SPE can fully recover after repeated damage, conferring the derived soft-pack battery stable powering capacity upon multi-angle bending and folding. The design of multi-armed and multiple charged PILs provides new avenues for developing flexible electronic devices with self-healing capacity.

关键词： solid-state lithium battery   polyurethane-based electrolytes   ultrahigh elasticity   robust electrode/electrolyte interface  

摘要： Solid polymer electrolytes (SPEs) are promising for solid-state lithium batteries, but their practical application is significantly impeded by their low ionic conductivity and poor compatibility. Here, we report an ultrahigh elastic SPE based on cross-linked polyurethane (PU), succinonitrile (SN), and lithium bistrifluoromethanesulfonimide (LiTFSI). The resulting electrolyte (PU-SN-LiTFSI) exhibits an ionic conductivity of 2.86 x 10(-4) S cm(-1), a tensile strength of 3.8 MPa, and a breaking elongation exceeding 3000% at room temperature. A solid-state lithium battery using the electrolyte exhibits a high specific capacity of 150 mAh g(-1) at 0.2C and a long cycling life of up to 700 cycles at 0.5C at room temperature, showing one of the best performances among its counterparts. The excellent performances are attributed to the fact that its ultrahigh elasticity, good ionic conductivity, tensile strength, and electrochemical stability contribute to robust electrode/ electrolyte interfaces, thus greatly decreasing the charge-transfer resistance in charge/discharge processes. Our investigations provide a novel strategy to address the intrinsic interfacial issue of solid-state batteries.

关键词： Particles   Composite polymer electrolyte   Ionic conductivity   Interaction   Interface   Solid-state  

摘要： Solid-state lithium batteries(SSLBs)have been identified as one kind of the most promising energy conversion and storage devices because of their safety,high energy density,and long cycling *** development of solid-state electrolyte is vital to commercialize *** polymer electrolyte(CPE),derived by compositing inorganic particles into solid polymer electrolyte has become the most practical species for SSLBs because it inherits the advantages of polymer electrolyte and simultaneously achieves enhanced ionic conductivity and mechanical *** characteristics of inorganic particles and their interaction with polymers strongly impact the performance of CPE,improving its ionic conductivity,mechanical properties,thermal and electrochemical stability,as well as interface compatibility with both *** this review,the effects of particle characteristics including its species,size,proportion,morphology on the ionic conductivity and mechanical properties of CPE are ***,some novel composite strategies are also introduced including surface modification,hybridization,and alignment of particles in polymer matrices,as well as some new preparation methods of *** interactions between particles and other components in CPE including polymer matrices or lithium salt are particularly focused herein to reveal the lithium conductive ***,a perspective on the direction of future CPE development for SSLBs is presented.

关键词： solid-state lithium batteries   poly(ethylene oxide)   Li1.3Al0.3Ti1.7(PO4)(3) coating   polyethylene separator   electrolyte/anode interface   composite solid-state electrolytes  

摘要： Poly(ethylene oxide) (PEO)-based solid-state lithium batteries (SSLBs), accompanied by potential high energy density and reliable safety, have attracted wide attention. However, PEO-based solid-state electrolytes (SSEs) are hard to scale up due to their low oxidation stability, low ionic conductivity at room temperature, and relatively poor mechanical properties. Here, a PEO-based ceramic-polymer (PCP) composite SSE is designed. The porous Li1.3Al0.3Ti1.7(PO4)(3) (LATP)-coated polyethylene (PE) separator is filled with PEO/lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) solution, which possesses both a robust mechanical property and processable flexibility. The results show the PCP membrane effectively suppresses the growth of lithium (Li) dendrites identified by a flat Li deposition. It is attributed to the robustness of the PCP membrane itself and the formation of a mixed ionic/electronic conducting interphase (MCI) intertwined with a solid electrolyte interface (SEI) between the PCP membrane and the Li anode. The MCI-SEI intertwined mixed phase facilitates the homogeneous Li deposition and enhances the cycle stability of the electrolyte/anode interface. Hence, the PCP membrane effectively prevents short-circuiting and shows a good cycling stability of more than 2000 h in a Li/PCP/Li symmetric cell with a current density of 0.2 mA cm(-2). at 60 degrees C. Moreover, the Li/PCP/LiFePO4 all-solid-state battery shows a stable cycling performance with 160 mAh g(-1) at 0.2C after 200 cycles at 60 degrees C. The results show the purposed PCP membrane based on a LATP-coated PE separator is easy to be fabricated and could be practical for many applications.