静电纺丝法制备POSS-(C_3H_6Cl)_8复合聚偏氟乙烯聚合物隔膜的结构与性能

为了提高锂离子电池的安全性,文中选择聚偏氟乙烯(PVDF)为聚合物基体,八氯丙基低聚倍半硅氧烷(POSS-(C_3H_6Cl)_8)为改性剂,通过静电纺丝法制备POSS-(C_3H_6Cl)_8复合PVDF聚合物隔膜(EPS)。表征了纺丝膜的形貌、力学性能,测试了电化学窗口和Li/LiFePO_4纽扣电池的充放电循环稳定性。结果表明,当POSS-(C_3H_6Cl)_8的加入量为10%时,静电纺丝纤维薄膜的拉伸强度和断裂伸长率分别比纯PVDF提高了106.4%和27.2%;室温下的离子传导率为3.8×10~(-3)S/cm,比纯PVDF提高了97.4%;电化学稳定窗口为5.7 V。用该聚合物隔膜组装的锂离子电池具有良好的循环稳定性和倍率性能。     

PVDF/PMMA/PEG/TiO_2型聚合物隔膜的制备

为提高锂离子电池聚偏氟乙烯(PVDF)基聚合物隔膜的导电性和降低PVDF基聚合物隔膜的结晶度,引入聚甲基丙烯酸甲酯(PMMA)与聚偏氟乙烯(PVDF)进行共混,掺杂有机添加剂PEG和无机纳米材料TiO_2,采用相转化方法制备PVDF/PMMA/PEG/TiO_2型聚合物隔膜。通过对制备的PVDF/PMMA/PEG/TiO_2型多孔膜吸液率、离子电导率、微观形貌和电化学性能等的分析研究,确定制膜的最佳工艺条件为聚合物浓度为8%,PMMA占聚合物质量百分比为30%,PEG含量为30%,纳米TiO_2含量为5%,C2H5OH含量为3%,反应温度为45℃。该最优方案下制备的多孔膜结晶度较纯PVDF薄膜结晶度降低,多孔膜吸液率达345%,离子电导率达5.2mS/cm,拉伸强度为1 183kg/cm~2,电化学稳定窗口为4.68V,高于4.5V,能够满足锂离子电池正常工作需要。     

P(MMA-AN)的合成及其凝胶电解质的制备与性能

以甲基丙烯酸甲酯(MMA)和丙烯腈(AN)为单体,自由基引发聚合合成了聚(甲基丙烯酸甲酯-丙烯腈)[P(MMA-AN)]无规共聚物。采用红外光谱分析及元素分析法对共聚物的结构进行了表征。然后以此P(MMA-AN)无规共聚物为基体制备共聚物含量分别为30%、40%、50%(质量分数)的凝胶聚合物电解质(GPE)。采用交流阻抗法对其电性能进行表征。结果发现当MMA与AN投料比为1:3且共聚物在凝胶聚合物电解质中质量分数为30%时,GPE体系电导率达到最大值。     

PVDF/PMMA/TiO_2型聚合物隔膜的制备

为提高锂离子电池聚偏氟乙烯(PVDF)基聚合物隔膜的导电性和降低PVDF基聚合物隔膜的结晶度,引入聚甲基丙烯酸甲酯(PMMA)与聚偏氟乙烯(PVDF)进行共混,掺杂无机纳米材料TiO_2,采用相转化方法制备PVDF/PMMA/TiO_2型聚合物隔膜。通过对制备的PVDF/PMMA/TiO2型多孔膜吸液率、微观形貌和电化学性能的分析研究,确定制膜的最佳工艺条件为聚合物浓度为5%,PVDF∶PMMA为72∶28,纳米TiO_2添加量为5%,非溶剂添加量为3%,水浴温度为55℃。该方案下制备的多孔膜结晶度较纯PVDF薄膜结晶度降低,吸液率达到109.76%,离子电导率为2.64mS/cm,电化学稳定窗口为4.86V,高于4.5V,能够满足锂离子电池正常工作需要。     

PMMA-b-PS结构及有机累托石对其凝胶聚合物电解质性能的影响

通过原子转移自由基聚合反应(ATRP)合成3种嵌段比不同的聚甲基丙烯酸甲酯-b-聚苯乙烯(PMMA-b-PS),研究其嵌段比例对凝胶聚合物电解质(GPE)电性能的影响。结果发现,以3种嵌段共聚物为基体的GPE导电性均优于纯PMMA基GPE,这可能是因为刚性链段的存在改变了凝胶体系的自由体积;当聚合物含量为40%(质量分数)时,PMMA-b-1PS基GPE的电导率最高。选择电性能较优的PM-MA-b-1PS为基体,研究有机累托石(OREC)对该凝胶电解质(NGPE)性能的影响。在保持凝胶体系固含量为40%(质量分数),OREC添加量为聚合物的3%(质量分数)时,室温下NGPE的电导率达到了3.11×10-4S/cm,约为PMMA基GPE的18倍;热失重分析表明,质量损失5%时,PMMA-b-1PS基GPE热分解温度比PMMA基GPE热分解温度高66.1℃,NGPE的热分解温度相比PMMA基GPE提高了78.0℃。     

高离子电导率聚离子液体基自修复固态电解质的制备EI北大核心CSCD

采用可逆加成-断裂链转移(RAFT)聚合法成功合成了高分子量、窄分布的聚[1-(4-乙烯基苄基)-3-甲基咪唑双三氟甲烷磺酰亚胺](P[VBMIM][TFSI]),并将其与双三氟甲烷磺酰亚胺锂(LiTFSI)共混,通过溶液浇筑法制备了固态聚合物电解质(SPEs)。首先通过力学性能、流变学、热分析和电化学测试研究了P[VBMIM][TFSI]本体结构与性能的关系。随相对分子质量增加,P[VBMIM][TFSI]缠结程度逐渐加深,拉伸强度大幅度提升,而离子电导率与热降解温度变化不大。进一步对固态聚合物电解质进行更深入的电化学测试和分析。结果表明,SPEs在30℃时离子电导率最高可达到4.06×10^(-4) S/cm,锂离子迁移数为0.34,电化学窗口达到了4.5V。通过光学显微镜观察其自修复性,SPEs在室温时20min便可平复表面划痕,且具备良好的弹性,可以在5min内几乎完全回复拉伸长度。     

PEO/PPC/Nano TiO_2-PMMA复合聚合物电解质膜的制备及性能

以聚甲基乙撑碳酸酯(PPC)和聚氧化乙烯(PEO)为基体材料,添加经聚甲基丙烯酸甲酯(PMMA)接枝改性的纳米TiO2(nano TiO2-PMMA),采用溶液浇铸法制备了锂离子电池PEO/PPC/TiO2-PMMA复合聚合物电解质(CPE)膜。用热重分析、红外光谱、交流阻抗、扫描电镜等方法研究了nano TiO2-PMMA对复合聚合物电解质膜的电化学性能影响。结果表明,当TiO2的接枝率为8.0%时,PEO/PPC/TiO2-PMMA复合聚合物电解质膜具有良好的电化学性能:室温离子电导率达到1.3×10-5 S/cm,电化学稳定窗口达到4.5V以上,锂离子迁移数为0.49。     

静电纺PMMA/EVOH-SO3Li锂离子电池隔膜复合材料的制备及性能

以聚甲基丙烯酸甲酯（PMMA）和聚乙烯-乙烯醇磺酸锂（EVOH-SO₃Li）为原料,通过高压静电纺丝法进行交替纺丝,制备PMMA/EVOH-SO₃Li锂离子电池隔膜复合材料。通过FTIR、SEM、万能拉伸试验仪、TGA、IM6型电化学工作站和电池循环测试设备对PMMA/EVOH-SO₃Li隔膜复合材料的性能进行检测表征。结果表明：PMMA/EVOH-SO₃Li隔膜复合材料具有清晰的三维网状结构,与EVOH-SO₃Li隔膜材料相比,改性后PMMA/EVOH-SO₃Li隔膜复合材料的孔隙率、吸液率和拉伸强度分别提高至80%、340%和3.18 MPa,起始热分解温度升高至294℃,热收缩率也有所降低,并表现出良好的电化学性能。其中电化学稳定窗口由5.0V增加到5.6 V,界面阻抗由420.69 Ω降低至262.31 Ω,离子电导率则由1.560×10^-3 S/cm提高至2.089×10^-3 S/cm,并且经过100次循环充放电后,容量保持率仍高达93.7%。     

POSS-(PMMA46)8浸渍涂覆商业PP隔膜的结构与性能

为了提高锂离子电池的安全性能,降低其界面阻抗,选用既具有优异耐热性能又与聚合物有良好相容性的POSS杂化聚甲基丙烯酸甲酯(POSS-(PMMA 46 ) 8)作为改性剂,通过在商业聚丙烯(PP)隔膜上浸渍POSS-(PMMA 46 ) 8制备改性商用PP隔膜,分析隔膜的力学性能、热收缩性能、界面性能、离子电导率及电化学性能。结果表明:当POSS-(PMMA 46 ) 8质量分数为40%时,复合膜的孔丰富均一,润湿性最佳,拉伸强度是未改性前的5.34倍,且在160℃/1h下具有较高的热稳定性。此复合膜电导率为1.35×10 -3 S/cm,与电极的界面阻抗由原来的743Ω降为152Ω;Li/改性隔膜/LiFePO 4扣式电池的充放电循环稳定性较好,低倍率下的电池容量与商业PP隔膜相当。     

聚硅氧烷对水性聚氨酯聚合物电解质结构形态及电化学性能的影响

将PDMS引入到WPU中,合成了PEO-PDMS混合软段WPU嵌段共聚物,通过改变PDMS的含量得到一系列固态聚合物电解质膜。测试结果表明,PDMS的加入会对聚合物电解质材料的力学性能、微观形态、电化学性能产生显著影响。PDMS的加入可有效地提高聚合物电解质的室温电导率及电化学稳定性,30℃时样品C17-10电导率为1.05×10-4S/cm,其电化学稳定窗口达到5.5V。     

Minimization of Ion–Solvent Clusters in Gel Electrolytes Containing Graphene Oxide Quantum Dots for Lithium‐Ion Batteries

This study uses graphene oxide quantum dots (GOQDs) to enhance the Li⁺‐ion mobility of a gel polymer electrolyte (GPE) for lithium‐ion batteries (LIBs). The GPE comprises a framework of poly(acrylonitrile‐co‐vinylacetate) blended with poly(methyl methacrylate) and a salt LiPF₆ solvated in carbonate solvents. The GOQDs, which function as acceptors, are small (3?11 nm) and well dispersed in the polymer framework. The GOQDs suppress the formation of ion?solvent clusters and immobilize anions, affording the GPE a high ionic conductivity and a high Li⁺‐ion transference number (0.77). When assembled into Li|electrolyte|LiFePO₄ batteries, the GPEs containing GOQDs preserve the battery capacity at high rates (up to 20 C) and exhibit 100% capacity retention after 500 charge?discharge cycles. Smaller GOQDs are more effective in GPE performance enhancement because of the higher dispersion of QDs. The minimization of both the ion?solvent clusters and degree of Li⁺‐ion solvation in the GPEs with GOQDs results in even plating and stripping of the Li‐metal anode; therefore, Li dendrite formation is suppressed during battery operation. This study demonstrates a strategy of using small GOQDs with tunable properties to effectively modulate ion?solvent coordination in GPEs and thus improve the performance and lifespan of LIBs.     

Gel/Solid Polymer Electrolytes Characterized by In Situ Gelation or Polymerization for Electrochemical Energy Systems

A gel polymer electrolyte (GPE) is a liquid electrolyte (LE) entrapped by a small amount of polymer network less than several wt%, which is characterized by properties between those of liquid and solid electrolytes in terms of the ionic conductivity and physical phase. Electrolyte leakage and flammability, demerits of liquid electrolytes, can be mitigated by using GPEs in electrochemical cells. However, the contact problems between GPEs and porous electrodes are challenging because it is difficult to incorporate GPEs into the pores and voids of electrodes. Herein, the focus is on GPEs that are gelated in situ within cells instead of covering comprehensive studies of GPEs. A mixture of LE and monomer or polymer in a liquid phase is introduced into a pre‐assembled cell without electrolyte, followed by thermal gelation based on physical gelation, monomer polymerization, or polymer cross‐linking. Therefore, GPEs are formed omnipresent in cells, covering the pores of electrode material particles, and even the pores of separators. As a result, different from ex situ formed GPEs, the in situ GPEs have no electrode/electrolyte contact problems. Functional GPEs are introduced as a more advanced form of GPEs, improving lithium‐ion transference number or capturing transition metals released from electrode materials.     

In-situ thermal polymerization of rechargeable lithium batteries with poly(methyl methacrylate) based gel-polymer electrolyte

By heating the admixture of a commercial liquid electrolyte (LB302, 1 M solution of LiPF₆ in 1:1 EC/DEC), methyl methacrylate (MMA) and benzoyl peroxide (BPO, initiator), a poly(methyl methacrylate) (PMMA) based gel-polymer electrolyte (GPE) was obtained. AC impedance spectroscopy and cyclic voltammetry were used to evaluate its ionic conductivity and electrochemical stability window. Rechargeable cells LiNi_0.8Co_0.2O₂/Li and LiNi_0.8Co_0.2O₂/graphite with this MMA based GPE were also fabricated via the in-situ thermal polymerization process. This GPE exhibits a high ionic conductivity (over 10⁻³S cm⁻¹) at room temperature. It is stable in the voltage range between 0 and 4.2 V (vs. Li⁺/Li). A phenomenon of large initial cell impedance (LICI) was observed for the LiNi_0.8Co_0.2O₂/Li cells but not in LiNi_0.8Co_0.2O₂/graphite cells. After the first several cycles, the cell impedance decreases substantially and reversible charge–discharge capacity can be obtained. This in-situ polymerization method provides a way to produce GPE cells.     

基于高电导率的疏水气相SiO2复合凝胶电解质的高性能电致变色器件

凝胶电解质具有化学稳定、难燃和易于封装等特点,其低离子电导率(10-4～10-5 S·cm-1)阻碍了电致变色器件(ECDs)凝胶电解质的进一步发展.本研究制备了一种高电导率的疏水SiO2/PMMA/PC/LiClO4凝胶聚合物电解质(H-SiO2 GPEs),并用电化学阻抗谱(EIS)、循环伏安法(CV)和计时电流法...     

Effective Suppression of Lithium Dendrite Growth Using a Flexible Single‐Ion Conducting Polymer Electrolyte

A novel single‐ion conducting polymer electrolyte (SIPE) membrane with high lithium‐ion transference number, good mechanical strength, and excellent ionic conductivity is designed and synthesized by facile coupling of lithium bis(allylmalonato) borate (LiBAMB), pentaerythritol tetrakis (2‐mercaptoacetate) (PETMP) and 3,6‐dioxa‐1,8‐octanedithiol (DODT) in an electrospun poly(vinylidienefluoride) (PVDF) supporting membrane via a one‐step photoinitiated in situ thiol–ene click reaction. The structure‐optimized LiBAMB‐PETMP‐DODT (LPD)@PVDF SIPE shows an outstanding ionic conductivity of 1.32 × 10^?3 S cm^?1 at 25 °C, together with a high lithium‐ion transference number of 0.92 and wide electrochemical window up to 6.0 V. The SIPE exhibits high tensile strength of 7.2 MPa and elongation at break of 269%. Due to these superior performances, the SIPE can suppress lithium dendrite growth, which is confirmed by galvanostatic Li plating/stripping cycling test and analysis of morphology of Li metal electrode surface after cycling test. Li|LPD@PVDF|Li symmetric cell maintains an extremely stable and low overpotential without short circuiting over the 1050 h cycle. The Li|LPD@PVDF|LiFePO₄ cell shows excellent rate capacity and outstanding cycle performance compared to cells based on a conventional liquid electrolyte (LE) with Celgard separator. The facile approach of the SIPE provides an effective and promising electrolyte for safe, long‐life, and high‐rate lithium metal batteries.     

Crosslinked poly(acrylonitrile–glycidyl methacrylate) as a novel gel polymer electrolyte

Novel gel polymer electrolytes (GPEs) based on poly(acrylonitrile–glycidyl methacrylate) (P(AN–GMA)) crosslinked with α,ω-diamino poly(propylene oxide) (Jeffamine) of various weight ratios and molecular weights have been prepared, and the crosslinked polymers were characterized by FT-IR and thermal analysis. It is revealed that the crosslinked polymers were amorphous in pristine state and became crystallized when doped with lithium electrolyte. Their swelling properties and mechanical behaviors were investigated and found to be heavily affected by the weight ratio and molecular weight of Jeffamine. The effect of weight ratios and molecular weights of Jeffamine on the ionic conductivity of the GPEs based on the crosslinked polymers were determined by AC impedance spectroscopy. GPEs consisting of Jeffamine of higher molecular weights and increased weight ratios showed higher ionic conductivity. The GPE based on P(AN–GMA) crosslinked with Jeffamine D2000 at a weight ratio of 1.5 exhibited the highest ionic conductivity of 8.23 × 10^?4 S cm^?1 at 25 °C, and preserved a moderate mechanical strength. The crosslinked polymers can be potential candidates for the construction of rechargeable lithium batteries.     

Plastic crystal-incorporated magnesium ion conducting gel polymer electrolyte for battery application

Studies on a novel composition of magnesium ion conducting gel polymer electrolyte (GPE), comprising a solution of Mg-salt, magnesium trifluoromethanesulfonate (Mg-triflate or \(\hbox {Mg(Tf)}_{2})\) in a plastic crystal succinonitrile (SN), entrapped in a host polymer poly(vinylidenefluoride–hexafluoropropylene) (PVdF–HFP) was reported. Small amount of an ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) was added to stabilize the GPE composition. The electrolyte possesses excellent dimensional integrity in the form of free-standing thick film, which offers the ionic conductivity of \(4 \times 10^{-3} \hbox { S } \hbox {cm}^{-1}\) at room temperature \({\sim }26{^{\circ }}\hbox {C}\). The electrochemical potential window of the electrolyte, observed from the linear sweep voltammetry, is determined to be \({\sim }4.1 \hbox { V}\). The magnesium ion conduction in the GPE film is confirmed from cyclic voltammetry, electrochemical impedance spectroscopy and dc polarization techniques. Different structural, thermal and electrochemical studies demonstrate the promising characteristics of the polymer film, suitable as electrolyte in rechargeable magnesium batteries. The potential of the GPE as electrolyte/separator was ascertained by fabricating a prototype magnesium battery of the configuration Mg:graphite composite \(\hbox {anode}/\hbox {GPE}/\hbox {MnO}_{2}\)-cathode. The specific discharge capacity of \(40 \hbox { mAh g}^{-1}\) (with respect to the \(\hbox {MnO}_{2}\) cathode material) was obtained at the first discharge. The cell shows charge–discharge performance for eight cycles with a substantial fading in capacity.     

无纺布支撑微交联PMMA基凝胶聚合物电解质的制备与性能研究

以乙二醇二甲基丙烯酸酯(EGDMA))和聚乙二醇二丙烯酸酯(PEGDA)作交联剂,制备了PP无纺布支撑微交联PMMA基凝胶聚合物电解质。通过扫描电子显微镜、热重分析仪、电化学工作站和万能试验机对其表观形貌、热稳定性、室温离子电导率和拉伸强度进行了表征及测试。结果表明,PEG600DA和PEG200DA能有效提高体系的室温离子电导率,均从2.2 m S/cm提高到3.0 m S/cm左右;PEG400DA和PEG600DA能显著提高体系的拉伸强度,用量为0.3%和0.2%时,拉伸强度分别为11.8 MPa和12.4MPa,与对照相比分别提高39.1%和45.3%。     

A Polymer‐Reinforced SEI Layer Induced by a Cyclic Carbonate‐Based Polymer Electrolyte Boosting 4.45 V LiCoO2/Li Metal Batteries

Lithium (Li) metal batteries (LMBs) are enjoying a renaissance due to the high energy densities. However, they still suffer from the problem of uncontrollable Li dendrite and pulverization caused by continuous cracking of solid electrolyte interphase (SEI) layers. To address these issues, developing spontaneously built robust polymer‐reinforced SEI layers during electrochemical conditioning can be a simple yet effective solution. Herein, a robust homopolymer of cyclic carbonate urethane methacrylate is presented as the polymer matrix through an in situ polymerization method, in which cyclic carbonate units can participate in building a stable polymer‐integrated SEI layer during cycling. The as‐investigated gel polymer electrolyte (GPE) assembled LiCoO₂/Li metal batteries exhibit a fantastic cyclability with a capacity retention of 92% after 200 cycles at 0.5 C (1 C = 180 mAh g^?1), evidently exceeding that of the counterpart using liquid electrolytes. It is noted that the anionic ring‐opening polymerization of the cyclic carbonate units on the polymer close to the Li metal anodes enables a mechanically reinforced SEI layer, thus rendering excellent compatibility with Li anodes. The in situ formed polymer‐reinforced SEI layers afford a splendid strategy for developing high voltage resistant GPEs compatible with Li metal anodes toward high energy LMBs.     

纳米SiO2微球在PMMA凝胶聚合物电解质中的尺寸效应及其在全固态电致变色器件中的应用

本文采用St?ber法制备了不同粒径纳米SiO_2微球,将其加入到聚甲基丙烯酸甲酯(PMMA)基凝胶聚合物电解质中,研究了纳米SiO_2的尺寸效应及其对全固态电致变色器件性能的影响。研究发现,正硅酸乙酯和乙醇的体积比影响所得纳米SiO_2微球粒径大小,乙醇所占体积比例越大,制备的纳米SiO_2微球粒径越小。在PMMA基凝胶聚合物电解质中,当纳米SiO_2微球用量相同时,电解质的电化学窗口随着纳米SiO_2微球粒径的减小先增大后减小,离子电导率随纳米SiO_2微球粒径的增大而增大,在纳米SiO_2微球粒径为150 nm时电化学窗口达到最大,离子电导率的增速也变得不明显。当粒径为150 nm的纳米SiO_2微球含量为7wt%时,PMMA凝胶电解质的电化学窗口为4.8 V,电导率为1.13 mS/cm。以该电解质组装结构为:导电玻璃(ITO)‖SiO_2/碳酸丙烯脂(PC)-LiClO_4/PMMA‖金属-超分子聚合物‖ITO的透射式全固态电致变色器件,所得器件可在淡绿色和深蓝色之间变色,对比度高达60.1%,且器件的稳定性得以明显提高。