黏结剂对SnO_2/石墨烯负极材料电化学行为的影响

针对SnO2用作锂离子电池负极材料所存在的体积膨胀率高及导电性差的不足,考察了羧甲基纤维素钠(CMC)/丁苯橡胶(SBR)和聚偏氟乙烯(PVDF)黏结剂对SnO2、SnO2/石墨烯负极材料电化学性能的影响。结果表明:1)200 mA/g下经过30次充放电循环后,当以CMC/SBR作复合黏结剂时,SnO2的首次放电容量和容量保持率分别为581.3 mA·h/g和37.6%,明显高于PVDF作黏结剂时的电化学性能(135.3 mA·h/g、10.6%);2)200 mA/g下经过100次循环后,当以CMC/SBR作复合黏结剂时,SnO2/石墨烯复合负极材料的首次放电容量、容量保持率分别为702.3 mA·h/g和43.8%,也高于PVDF作黏结剂时的电化学性能(552 mA·h/g和32.8%)。     

漆多糖在锂离子电池硅碳负极粘结剂中的应用研究

高比容量硅碳材料被认为是最具应用前景的锂离子电池负极材料,但充/放电过程中硅的体积膨胀效应导致电极材料易粉碎和脱落,易造成电池容量快速衰减,因此开发可靠的硅碳负极粘结剂来提高电池循环稳定性尤为重要。本文对生漆提取漆酚后的乙醇溶剂不溶性物质进行分离,得到了水溶性物质漆多糖(LPS),TG和DSC测试结果表明LPS的热稳定性良好。将LPS作为粘结剂用于硅碳电极组装锂离子半电池,测试硅碳电极的电化学性能。与商用的油性粘结剂聚偏氟乙烯(PVDF)和水性海藻酸钠(SA)对比发现：基于LPS的电池表现出良好的循环稳定性,200次充放电循环后比容量仍高达471.5mAh/g,远高于SA(387.7mAh/g)和PVDF(221.4mAh/g)。本工作可为开发天然产物基锂离子电池水性粘结剂提供理论基础,开拓生漆研究新亮点。     

一种水性多功能粘结剂对锂硫电池性能的影响（急）

以海藻酸钠(SA)与聚乙烯亚胺(PEI)为原料，制备了一种具有交联网络结构的海藻酸钠交联聚乙烯亚胺（SAPEI）多功能锂硫电池正极水性黏结剂。研究了SAPEI黏结剂的黏结性、多硫离子吸附能力，以及对锂硫电池正极结构和电化学性能的影响。结果表明，SAPEI黏结剂的黏结强度高于传统商用（PVDF）黏结剂，同时反应过程中产生的酰胺键对多硫离子具有吸附作用。使用SAPEI黏结剂的锂硫电池在循环后硫正极呈现出更加均匀的微观形貌结构和更优的电化学性能。在0.2 C倍率下充放电200次后其放电比容量仍然保持在620 mA·h/g，容量保持率可达到72.5％，高于使用PVDF黏结剂的锂硫电池。     

PVDF包覆对锂离子电池硅碳负极性能的影响

以聚偏氟乙烯(PVDF)作为包覆材料,对硅碳复合负极材料进行了表面包覆。通过SEM对复合材料的形貌进行了表征,并研究了包覆材料的添加量对复合负极材料的电化学性能的影响。结果表明:PVDF的包覆对复合负极材料的循环性能具有提高作用。研究了包覆剂添加量对复合负极材料循环性能的影响,当添加量为5%时,复合负极的循环性能最佳,首效达到89.69%,循环500次的容量保持率为71.21%。     

多层共挤制备光纤外包覆PVC材料及性能研究

利用多层共挤法制备了光纤外皮用乙烯-乙烯醇共聚物(EVOH)、聚氯乙烯(PVC)、聚偏氟乙烯(PVDF)复合材料,以马来酸酐(MAH)为黏接剂,对复合材料强度进行优化,讨论了MAH含量与复合膜性能的关系。研究发现:EVOH、PVC、PVDF复合膜材料能够同时兼具良好的物理性能和较低的表面硬度、对水和氧气具有良好的阻隔性能和极佳的阻燃性能。MAH加入PVC中时,能够明显提高复合材料的拉伸强度、剥离强度和氧气阻隔性能,但会略微降低复合材料的氧指数。     

复合黏结剂制备CDI电极及其脱盐性能研究

电容去离子(CDI)是一种低能耗、环保的含盐水脱盐技术。电极对CDI系统的脱盐起着决定性作用。黏结剂对电极的性能有很大的影响，进而影响CDI脱盐性能。研究选用聚四氟乙烯(PTFE)和聚偏氟乙烯(PVDF)作为复合黏结剂，利用涂覆法制备活性炭电极，讨论其应用于CDI的可能性。采用流变、接触角、电阻率、SEM、BET、电化学测试等方法对电极性能进行表征，使用自制的脱盐装置，研究复合电极的脱盐性能。结果表明：涂覆电极呈现亲水性，具有较好的稳定性，50次循环伏安后比电容仅下降7.35%，最大比电容可达141.78 F·g^-1。随着PTFE的增加，电极亲水性、导电性以及强度略有下降，电极的稳定性略有上升。脱盐结果显示，PTFE/PVDF配比为5∶5时，电极具有良好的脱盐性能，脱盐量达到8.567 mg·g^-1。     

对甲基苯磺酸钠掺杂聚吡咯/二氧化钛纳米管阵列全电池的电化学储锂性能

采用电化学方法制备了对甲基苯磺酸钠掺杂的聚吡咯(TsONa/PPy)锂离子电池正极材料和二氧化钛纳米管阵列(TiO_2NT)负极材料。利用扫描电子显微镜和X射线能量色散光谱仪研究了样品的微观结构及形貌,并进一步组装成全电池,利用恒流充–放电和循环伏安(CV)技术测试了其电化学性能。结果表明:对甲基苯磺酸钠掺杂的聚吡咯正极材料是由直径为3μm左右的微球组成,二氧化钛负极材料则呈现三维有序纳米管阵列形貌,两种电极材料的表面皆凸凹不平;由二者组成的全电池首次放电比容量约为105 mA·h/g,经过50次循环后,可逆放电比容量仍保持在65 mA·h/g,表现了良好的循环稳定性,此外还表现了良好的倍率性能。     

一种用于磷酸铁锂电极的水性黏结剂制备与性能研究

磷酸铁锂作为锂离子电池正极材料应用广泛。目前在其电极制备中仍采用PVDF油系黏结剂体系,可用于该电极的水性黏结剂仍需进一步研究。通过反应型乳化剂共聚苯乙烯（St）与丙烯酸异辛酯（2-EHA）制备了不同结构的磷酸铁锂正极水系黏结剂PSEHA,探讨了黏结剂对电池性能的影响。PSEHA黏结剂不含不饱和双键,抗氧化性好,较低的溶胀率可以有效防止过度溶胀导致的结构破坏,而反应型乳化剂可以解决乳化剂残留问题。采用所得最优结构黏结剂制备的磷酸铁锂电极表现出优异的电化学稳定性,扣式电池1 C循环100圈后容量保留率仍有96%,而SBR仅有93.9%;软包全电池在1 C倍率下循环170圈后容量保留率仍有98.9%。该新型水性黏结剂对促进磷酸铁锂水性体系制备有重要意义。     

聚甲基乙撑碳酸酯/乙烯-乙烯醇共聚物/黏土复合材料的流变性能与阻透性能

采用熔融共混的方法制备了聚甲基乙撑碳酸酯(PPC)/黏土和PPC/乙烯-乙烯醇共聚物(EVOH)/黏土纳米复合材料,测试了复合材料的流变性能和阻氧性能,并对其微观形态进行了分析。结果表明,当基材PPC相对分子质量较高时,PPC/黏土复合材料的复数黏度、储能模量和耗能模量也较高;随着黏土和相容剂马来酸酐接枝聚乙烯（PE-g-MAH）的添加, PPC/EVOH复合材料的复数黏度和模量明显增加,PE-g-MAH的加入使PPC、EVOH和黏土之间的界面作用力增强,改善了PPC与EVOH的相容性,同时提高了PPC/EVOH复合材料的阻氧性能。     

多级ZnO纳米片/Fe负极的制备及锂电性能

通过电解液中NO_3~–的电化学还原、Zn(OH)_2的化学沉积及后续的水解反应,在Fe箔表面生成了一层多级ZnO纳米片(ZnONS),并研究了其微观形貌、微观结构、电化学储锂性能及反应机理。结果表明:多级ZnO纳米片确实形成并紧密结合在Fe箔表面,而且,用于锂离子电池负极时,多级ZnONS/Fe负极的首次充–放电比容量分别为633和1 564 mA·h/g,Coulomb效率为41%;第2次循环的充–放电比容量分别为564和595 mA·h/g,Coulomb效率增加到95%。循环充放电50次时,放电比容量仍达200 mA·h/g,表现了良好的循环稳定性和倍率性能。多级ZnONS/Fe负极的首次不可逆容量损失,主要与电解液的分解和固态电解质界面膜的形成有关。     

Nanocrystalline NiO thin film anode with MgO coating for Li-ion batteries

The nanocrystalline NiO thin films with the mean size of 30 nm are prepared by pulsed laser reactive ablation in an oxygen ambient and subsequent coated by MgO on the NiO film surface. As compared with bare NiO, coated NiO film electrode heat-treated at 500 °C exhibits excellent structural stability and electrochemical performance. Excellent electrochemical performance, a reversible capacity as high as 650 mAh/g in the range 0.01–3.0 V at high discharge rate of 2C with a high capacity retention up to 150 cycles, could be achieved with MgO-coated NiO films. Preliminary electrochemical cycling measurements show that capacity retention with capacity fading for bare NiO and MgO-coated NiO film electrodes are 0.43 and 0.28% per cycle, respectively, at the discharge rate of 2C after 150 cycles. This result is related to good structural stability of the MgO-coated NiO film as verified by cyclic voltammetric (CV) measurement and scanning electron microscopy (SEM) analysis.     

Fabrication and characterization of electrolyte membranes based on organoclay/tripropyleneglycol diacrylate/poly(vinylidene fluoride) electrospun nanofiber composites

Utilizing polymer electrospinning technology, novel electrolyte membranes based on poly(vinylidene fluoride) (PVDF)/organomodified clay (OC)/tripropyleneglycol diacrylate (TPGDA) composite nanofibers with a diameter of 100–400 nm were fabricated for application in lithium batteries. Ultraviolet photo‐polymerization of electrospun PVDF/OC/TPGDA nanofibers generated chemically crosslinked TPGDA‐grafted PVDF/OC nanofibers exhibiting robust mechanical and electrochemical properties. The prepared fibrous PVDF/OC/TPGDA electrolytes were characterized in terms of morphology, crystallinity, electrochemical stability, ionic conductivity and cell cycleability. Based on differential scanning calorimetry analysis, the crystallinity of PVDF decreased by ca 10% on employing the OC and TPGDA. Compared with pure PVDF film‐based electrolyte membranes, the TPGDA‐ and OC‐modified PVDF electrolyte membranes exhibited improved mechanical properties and various electrochemical properties. The OC‐ and TPGDA‐modified microporous membranes are promising candidates for overcoming the drawbacks of the lower mechanical stability of fibrous‐type electrolytes with further improvement of electrochemical performance. Copyright © 2009 Society of Chemical Industry     

Water‐soluble binder PAALi with terpene resin emulsion as tackifier for LiFePO4 cathode

Terpene resin (TS) emulsion has been adopted as a tackifier in lithium polyacrylate (PAALi) as water‐soluble binder for LiFePO₄ (LFP) cathode in Li‐ion batteries. TS–PAALi composite binder with optimal ratio of 1:1 (denoted as TS1–PAALi1), shows improved flexibility and enhanced adhesion capability of 0.170 N/cm in comparison with 0.120 N/cm of PAALi after introducing TS as adhesion enhancing agent, which is comparable with that of nonaqueous poly(vinylidene difluoride) (PVDF, 0.171 N/cm) and much better than aqueous sodium carboxymethyl cellulose (CMC, 0.045 N/cm). The electrochemical characteristics of LFP with TS1–PAALi1 have been investigated and further compared with those of PAALi, CMC, and PVDF. LFP with TS1–PAALi1 exhibits superior cycling stability and rate capability, maintaining 65.57% capacity of 0.2 C at 5 C rate in comparison with 60.73%, 57.83%, and 34.79% for PAALi, CMC, and PVDF, respectively. In addition, LFP with TS1–PAALi1 displays excellent cycling performance almost without any capacity fading at 60 °C after 45 cycles at 1 C, much better than that of PAALi, CMC, and PVDF. Cyclic voltammetry and electrochemical impedance spectroscopy reveal that LFP with TS1–PAALi1 has a smaller redox potential difference, lower electrode polarization, and a more favorable electrochemical kinetics (fast lithium diffusion rate) than that of PAALi, CMC, and PVDF, thus more superior electrochemical performances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46132.     

Aqueous processing based novel composite electrode for Li-ion batteries using an environmentally benign binder

Along with the high energy density and safer battery materials, easy and environment benign electrode processing is also one of the major concerns for the battery manufacturing industries. Therefore, herein, water-based electrode processing is used which reduces manufacturing cost and makes easy and cost-effective recycling of discarded batteries. In addition, the increasing use of Li-ion batteries from portable electronics to electric vehicles has imposed a threat to the environment due to hazardous materials used. The present study also focuses on the replacement of polyvinylidene difluoride (PVDF) non-conducting binder dissolves in toxic solvent N-methyl 2-pyrrolidone with water-soluble poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) conducting binder. The entire study is performed on the synergistic effect of PEDOT:PSS with multi-walled carbon nanotubes (MWCNTs or MC) and carbon black (CB) on Li-ion battery performance using LiFePO₄ cathode active material. The discharge capacities were found 144 mAh g⁻¹ and 160 mAh g⁻¹ at 0.1C for composite electrodes LFP/CB-9P and LFP/MC-9P, respectively having 9 wt% PEDOT:PSS. Whereas the composite electrodes LFP/CB-10PV and LFP/MC-10PV having 10 wt% PVDF binder show only capacities 117 mAh g⁻¹ and 134 mAh g⁻¹, respectively. The composite electrode LFP/MC-9P shows the highest capacities up to 20C rate and maximum retention capacity of 84% at 5C after 500 cycles among all samples studied. Whereas electrodes prepared with PVDF binder could not perform well at more than 5C current rate, capacity retention is also found nearly 0% after 500 cycles. Therefore, superior results of PEDOT:PSS and MWCNTs with LiFePO₄ propose an environmentally benign composite electrode of next generation Li-ion batteries for electric vehicles.     

Nanocrystalline NiO hollow spheres in conjunction with CMC for lithium-ion batteries

Hollow spherical NiO particles were prepared using the spray pyrolysis method with different concentrations of precursor. The electrochemical properties of the NiO electrodes, which contained a new type of binder, carboxymethyl cellulose (CMC), were examined for comparison with NiO electrodes with polyvinylidene fluoride (PVDF) binder. The electrochemical performance of NiO electrodes using CMC binder was significantly improved. For the cell made from 0.3 mol L⁻¹ precursor, the irreversible capacity loss between the first discharge and charge is about 43 and 24% for the electrode with PVDF and CMC binder, respectively. The cell with NiO–CMC electrode has a much higher discharge capacity of 547 mAh g⁻¹ compared to that of the cell with NiO–PVDF electrode, which is 157 mAh g⁻¹ beyond 40 cycles.     

Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m²/g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.     

Electrospun poly(vinylidene‐fluoride)/POSS nanofiber membrane‐based polymer electrolytes for lithium ion batteries

In this study, poly(vinylidene fluoride) (PVDF)/polyhedral oligomeric silsesquioxanes (POSS) nanofibrous membranes are prepared through electrospun process. Field emission scanning electron microscope images clearly show that PVDF/POSS membranes have interconnected multi fibrous layers with ultrafine porous structures. The average fiber diameter and crystallinity of PVDF/POSS membranes are lesser than that of pure PVDF membrane. Thermal stability and electrolyte uptake of blend membranes increase with increasing POSS content. Finally, PVDF/POSS membranes are soaked in a liquid electrolyte to form the polymer electrolytes and are assembled in coin cells to test their electrochemical properties such as ionic conductivity, interfacial characteristics, and electrochemical stability windows. The ionic conductivity improves with increasing POSS content and the highest ionic conductivity reaches 2.91 × 10⁻³ S/cm at room temperature. It is also worth mention that the composite polymer electrolytes show low interfacial resistance and high electrochemical stability window of 5.6 V (vs. Li⁺ /Li) with storage time. POLYM. COMPOS., 38:629–636, 2017. © 2015 Society of Plastics Engineers     

聚丙烯腈/聚酯无纺布微孔复合锂电隔膜的制备及性能

为了改善锂电隔膜的耐热性、电解液亲和性和机械性能,本文以聚丙烯腈为主要材料,采用相转化法制备了聚酯无纺布支撑的聚丙烯腈微孔复合锂电隔膜,对隔膜的理化性能（孔道结构、机械性能、电解液性能和耐热性）和电池性能（循环性能、倍率性能）进行系统研究。结果表明,复合隔膜具有均匀的微孔结构,平均孔径约为425nm,孔隙率为74%,拉伸强度为30MPa;电解液亲和性良好,吸液率为385%,接触角接近0°,锂离子电导率较市售隔膜显著提高,达到1.65mS/cm;在150℃、0.5h的热处理条件下,复合隔膜的热收缩率为0。鉴于良好的理化特性,该隔膜所装配的钴酸锂/锂金属电池表现出优异的循环容量和倍率容量保持性,如在0.2C倍率下,经历200次循环后电池的放电容量保持率为95.2%,在10C倍率下电池的放电容量为0.5C倍率下的58.3%。因此,相转化法制备的聚丙烯腈基微孔复合隔膜在锂离子电池中显示出较好的应用前景。