废旧磷酸铁锂材料碳热还原固相再生方法

采用热处理方法将回收的正极片除去黏结剂,同时将LiFePO₄氧化为Li₃Fe₂（PO₄）₃及Fe₂O₃并作为再生反应原料,分别以葡萄糖、一水合柠檬酸、聚乙二醇为还原剂,650℃高温反应16h、20h、24h碳热还原再生LiFePO₄。测试结果表明,3个还原剂体系均能获得再生LiFePO₄材料。以葡萄糖为还原剂,高温反应16h、20h、24h,放电比容量分别为118.49mA·h/g、118.38mA·h/g、123.77mA·h/g;100次循环后,容量保持率分别为88.40%、80.07%、72.56%。还原剂对再生材料性能影响显著,以葡萄糖为还原剂,再生材料的容量特性及循环性能均最优,一水合柠檬酸还原剂体系次之,聚乙二醇还原剂体系电化学性能最差。研究结果为大规模废旧LiFePO₄材料再生提供一种新的途径。     

Long-term cyclability of nanostructured LiFePO4

Amorphous LiFePO₄ was obtained by lithiation of FePO₄ synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH₄)₂(SO₄)₂·6H₂O and NH₄H₂PO₄, using hydrogen peroxide as oxidizing agent. Nano-crystalline LiFePO₄ was obtained by heating amorphous nano-sized LiFePO₄ for different periods of time. The materials were characterized by TG, DTA, X-ray powder diffraction, scanning electron microscopy (SEM) and BET. All materials showed very good electrochemical performance in terms of energy and power density. Upon cycling, a capacity fading affected the materials, thus reducing the electrochemical performance. Nevertheless, the fading decreased upon cycling and after the 200th cycle the cell was able to cycle for more than 500 cycles without further fading.     

A Facile Route for Synthesis of LiFePO4/C Cathode Material with Nano-sized Primary Particles

A facile and practical route was introduced to prepare LiFePO4/C cathode material with nano-sized primary particles and excellent electrochemical performance. LiH2PO4 was synthesized by using H3PO4 and LiOH as raw materials. Then, as-prepared LiH2PO4, reduced iron powder andα-D-glucose were ball-milled, dried and sin-tered to prepare LiFePO4/C. X-ray diffractometry was used to characterize LiH2PO4, ball-milled product and LiFePO4/C. Differential scanning calorimeter-thermo gravimetric analysis was applied to investigate possible reac-tions in sintering and find suitable temperature for LiFePO4 formation. Scanning electron microscopy was em-ployed for the morphology of LiFePO4/C. As-prepared LiH2PO4 is characterized to be in P21cn（33） space group, which reacts with reduced iron powder to form Li3PO4, Fe3（PO4）2 and H2 in ball-milling and sintering. The appro-priate temperature for LiFePO4/C synthesis is 541.3-976.7 ℃. LiFePO4/C prepared at 700 ℃ presents nano-sized primary particles forming aggregates. Charge-discharge examination indicates that as-prepared LiFePO4/C displays appreciable discharge capacities of 145 and 131 mA·h·g^-1 at 0.1 and 1 C respectively and excellent discharge ca-pacity retention.     

水热法一步合成磷酸铁锂及其性能研究

为优化液相法一步制备磷酸铁锂（LiFePO₄）技术,以七水合硫酸亚铁、磷酸二氢铵、一水合氢氧化锂为原料,通过添加十二烷基苯磺酸钠（SDBS）作为表面活性剂,采用液相水热法合成技术,一步合成了LiFePO₄正极材料。研究了水热法一步合成技术对LiFePO₄材料的组成、结构、形貌、粒度等的影响,通过电感耦合等离子体发射光谱仪（ICP-OES）、X射线衍射仪（XRD）、扫描电镜（SEM）、粒度分析仪等对材料进行了表征分析,并测试了材料的电化学性能。研究结果表明,合成得到的LiFePO₄材料为微米级球形颗粒形貌的正交晶系非化学计量比的Li_1.02Fe_0.994PO₄材料。电化学性能测试结果表明,在0.1C倍率下首次充、放电比容量分别为162.0、159.9 mA·h/g,库伦效率达到98.7%、倍率性能（以1C/0.1C保持率计）为92.3%,0.1C倍率循环100次容量保持率为96.4%,展现出良好的电化学性能。     

前驱体二水磷酸铁对磷酸铁锂电化学性能的影响

以钛白生产副产物七水硫酸亚铁为铁源,工业磷酸二氢铵为磷源,双氧水为氧化剂,采用共沉淀法合成了不同粒径和形貌的二水磷酸铁,并以此为前驱体,通过碳热还原法制备了粒径不同的LiFePO₄/C正极材料。经过对样品进行X射线衍射（XRD）、扫描电镜（SEM）以及恒电流充放电测试,研究了二水磷酸铁及LiFePO₄/C的结构、形貌以及电化学性能。结果表明,以较细的二水磷酸铁为铁源,制备得到的LiFePO₄/C颗粒较细,且具有更优异的电化学性能。0.1、0.5、1、2、5、10 C放电比容量分别为154、148、144、140、130、120 mA·h/g。     

Synthesis of sub-micrometer lithium iron phosphate particles for lithium ion battery by using supercritical hydrothermal method简

A supercritical hydrothermal method was employed to prepare sub-micrometer LiFePO4 particles with high purity and crystallinity. The structure and morphology of LiFePO4 particles were characterized by X-ray diffraction and scanning electron microscope. The electrochemical tests were carried out to determine the reversible capacity, rate and cycling performance of the LiFePO4 particles as cathode material for lithium ion battery. Experimental results show that solvent and calcining time have significant effects on purity, size and morphology of LiFePO4 particles. Mixed solvent contained deionized water and ethanol is conducive to synthesize smaller and more uniform particles. The size of LiFePO4 particles as-prepared is about 100-300 nm. The specific discharge capacities of the LiFePO4 particles are 151.3 and 128.0 mA. h. g-1 after first cycle at the rates of 0.1 and 1.0 C, respectively. It retains 95.0% of the initial capacity after 100 cycles at 1.0 C.     

LiFePO4/C cathode materials synthesized by co-precipitation and microwave heating

LiFePO₄/C cathode materials were synthesized by a combination of co-precipitation and microwave heating using polyethylene glycol (PEG) as a carbon resource and the influence of microwave heating time on the structure and electrochemical performance of the materials was also discussed. The samples were characterized by X-ray diffraction (XRD), TEM, particle-size analysis and constant current charge-discharge experiment. The results show that the LiFePO₄/C heated for 9 min has a pure olive-type phase and excellent electrochemical performance. The initial discharge capacities of this sample are 154.3, 139.7, 123.9 mAh/g at the rates 0.1C, 0.2C, 1C at room temperature, respectively, and after 20 cycles remain 152.3, 134.3, 118.5 mAh/g, respectively. __________ Translated from New Chemical Materials, 2008, 36(2): 21–24 [译自:化工新型材料]     

磷酸铁锂正极材料的制备及性能强化研究进展

橄榄石型磷酸铁锂是目前应用十分广泛的锂离子电池正极材料之一,具有成本低、安全性高、环境友好、循环寿命长和工作电压稳定的特点。近年来,随着CTP技术、刀片电池技术等取得的突破性进展,磷酸铁锂的商业化程度得到了大幅提高。但磷酸铁锂存在电子导电性较差和离子扩散系数低的缺陷,严重限制了锂离子电池的电化学容量,因此开展磷酸铁锂制备工艺和性能强化研究对磷酸铁锂的性能提升具有重要意义。对比了磷酸铁锂电池与其他正极材料锂离子电池的性能差异和发展现状,系统总结了磷酸铁锂正极材料制备与强化的改性方法及相关研究进展与挑战,并提出了未来的发展方向与研究思路。     

镁离子掺杂磷酸铁锂的制备及其电化学性能

通过简单水热反应制备磷酸铁锂前驱体,并结合后期热处理过程制备了镁离子掺杂碳包覆的磷酸铁锂正极材料。利用X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等表征了镁离子掺杂磷酸铁锂的成分、形貌和结构。元素分布结果证明镁离子均匀掺杂在磷酸铁锂材料中。通过恒流充放电和循环伏安、交流阻抗等方法对材料的电化学性能进行测试。结果表明,镁离子掺杂后的磷酸铁锂材料具有较高的放电比容量（0.1C放电比容量为 160.1 mA·h/g）和优越的倍率性能（20C放电比容量为77.2 mA·h/g）,同时减小了极化和电荷迁移电阻。这条合成路线是提高水热法制备磷酸铁锂正极材料电化学性能的有效方法。     

Influence of synthesis parameters on the properties of LiFePO4/C cathode material☆

The influence of sintering temperature,carbon content and dispersive agent in ball-milling was investigated on the properties of Li Fe PO_4/C prepared using Fe_2O_3,NH_4H_2PO_4,Li_2CO_3 and glucose via solid state reaction.X-ray powder diffraction,scanning electron microscopy and charge–discharge test were applied to the characterization of the Li Fe PO_4/C samples synthesized under different conditions.Sintering temperature affects the crystallite/particle size and degree of crystallinity of LiF eP O_4,formation of Fe_2 P and maintenance of carbon in LiF e PO_4/C.Carbon maintenance is favored by low sintering temperature,and 700 °C is optimum for synthesis of LiF eP O_4/C with superior electrochemical performance.A higher carbon content in the range of 4.48%–11.03% results in a better rate capability for Li Fe PO_4/C.The dispersive agent used in ball-milling impacts the existent state of carbon in the final product which subsequently determines its charge–discharge behavior.The sample prepared at700 °C by using acetone as the dispersive agent in ball-milling exhibits an excellent rate capability and capacity retention without any fade at 0.1C,1C and 2C,with corresponding average discharge capacities of 153.8,128.3and 121.0 m A·h·g~(-1),respectively,in the first 50 cycles.     

片状LiFePO4/C正极材料制备及其电化学性能研究

在温和的反应条件下，使用十二烷基苯磺酸钠(SDBS)成功合成了片状二水磷酸铁，并将其与氢氧化锂、柠檬酸球磨混合，采用碳热还原法制备了具有纳米厚度的片状LiFePO₄/C电极材料。研究了SDBS对磷酸铁形貌以及LiFePO₄/C电极材料电化学性能的影响。利用X-射线衍射、扫描电子显微镜和充放电测试等技术手段，对合成样品的物相、形貌和电化学性能进行了分析测试。电化学测试表明，在25℃，2.0～4.2 V电压范围条件下，使用片状二水磷酸铁为前驱体制备的LiFePO₄/C样品，在0.1 C下放电比容量高达166.4 mA·h·g^-1，且首次库仑效率达到99.6%，在1 C下循环500次容量保持率为99%，表现出了优异的电化学性能。     

锂离子电池磷酸铁锂正极材料的研究进展

磷酸铁锂正极材料因其优良的电化学性能,被认为是最具应用前景的锂离子电池正极材料之一。但由于其导电率低和锂离子扩散速率慢等问题,一直制约其发展。本文阐述了磷酸铁锂的晶体结构、充放电原理以及电化学反应模型,回顾了近年来国内外对于改善磷酸铁锂的电化学性能所进行的研究,重点介绍了离子掺杂、碳包覆以及材料纳米化等改性方法对锂离子电池磷酸铁锂正极材料的影响以及目前仍然存在的问题,最后展望了该领域的发展趋势,指出继续进行深入的理论研究和进行工艺改进将是今后重点的研究方向。     

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。     

A PVB-based rheological phase approach to nano-LiFePO4/C composite cathodes

Nano-LiFePO₄/C cathode materials were synthesized by a PVB-based rheological phase method, followed by calcination at 550 °C for 10 h in argon. Simultaneous thermogravimetric-differential scanning calorimetry analysis indicates that the crystallization temperature of LiFePO₄ is about 436 °C. In the process of heat treatment, the decomposition of polyvinylbutyral coats carbon on the synthesized LiFePO₄ particles in situ. The resulting LiFePO₄ powders with fine particle sizes and homogeneous carbon network connection were observed by using scanning electron microscopy and transmission electron microscopy. Electrochemical measurements show that the LiFePO₄/C composite cathode delivers a large discharge capacity of 162.3 mAh·g^− 1 at the 0.1 C rate, and exhibits a favorable capacity cycling maintenance at lower charge and discharge rate such as 0.5 C rate.     

锂离子电池正极材料磷酸铁锂的研究进展

磷酸铁锂（LiFePO₄）具有高温稳定性较好、循环性能良好、环保等特点,已成为锂离子动力电池正极材料之一。但由于磷酸铁锂电导率低及锂离子扩散速率慢等缺点,制约其在动力电池行业的发展。因此主要从包覆碳材料对磷酸铁锂进行表面改性、对磷酸铁锂进行掺杂、制备亚微米或纳米级的磷酸铁锂或制备特殊形貌的磷酸铁锂3方面进行综述,分析改善磷酸铁锂性能最优的方法,对其未来的发展趋势进行了预测。     

纳米核壳二氧化钛的可控制备及储锂性能研究

以氟钛酸铵为钛源,采用尿素和双氧水控制Ti4+水解速率,经过一步水热,制备出了锐钛矿型的二氧化钛核壳纳米结构,500 ℃煅烧处理得到电极材料。采用X射线衍射（XRD）、场发射扫描电镜（FESEM）、恒流充放电及循环伏安测试对材料的结构、形貌和电化学性能进行表征。结果表明产物形貌尺寸均一,分散性较好。与市售二氧化钛纳米颗粒相比,二氧化钛核壳纳米结构具有多孔结构及优异的结构稳定性,从而具有更好的循环性能和倍率性能。在0.1C倍率下,二氧化钛核壳纳米结构放电比容量为344 mA·h/g,当放电倍率提高到10C时,仍然具有72 mA·h/g的放电比容量。在1C的放电倍率下,经过100次循环,二氧化钛核壳纳米结构放电容量保持率为80%。     

高硫石油焦基活性炭的制备及其在二次电池负极材料中的应用

以我国产量较大的山东淄博高硫石油焦为原料,利用KOH活化法,于800℃下通过改变碱焦质量比(质量比为1∶1,2∶1,3∶1,4∶1)制备得到不同比表面积的高硫石油焦基活性炭(AC-PC-X),利用比表面积分析仪对其孔结构进行了分析,并进一步利用水热法担载Mn₃O₄制备得到AC-PC-X/Mn₃O₄复合材料,分别将AC-PC-X/Mn₃O₄和高硫石油焦基活性炭作为二次电池负极材料分别应用于锂离子电池和钾离子电池中,利用JSM-7001F型热场发射扫描电子显微镜和JEM-2100F型场发射透射电子显微镜观察了负极材料的微观形貌,以及利用LAND CT2001A型电池测试系统和CHI660D型电化学工作站考察了负极材料的性能。结果表明:不同碱焦质量比条件下制备得到的高硫石油焦基活性炭均以微孔结构为主,比表面积随碱焦质量比的增加而增大;碱焦质量比为3∶1时制备得到的高硫石油焦基活性炭(AC-PC-3,比表面积为996m²/g)表现出最佳的长期循环稳定性,比表面积过大或过小的高硫石油焦基活性炭的电化学稳定性均不如ACPC-3的电化学稳定性。在锂离子电池中,AC-PC-3/Mn₃O₄在初始循环中的比容量为907mAh/g,但其循环容量衰减较慢,120次充/放电循环后其稳定比容量为400mAh/g;在钾离子电池中,ACPC-3在500次循环后比容量几乎没有衰减,稳定在95mAh/g。     

正极材料LiFePO4/C掺杂改性的研究进展

LiFePO₄/C具有高温稳定性好、价格低廉、循环性能良好、环保等性能,是一种具有发展潜力的锂离子动力电池正极材料之一,因此在锂离子电池行业备受关注。但由于其电子电导率低以及锂离子扩散速率慢等缺点制约其发展。介绍了磷酸铁锂的结构、性能、充放电原理和掺杂机理,尤其对近年来LiFePO₄/C材料的掺杂改性研究进行了综述。     

类球形低硫磷酸铁的制备技术研究

磷酸铁（FePO₄）是锂电池正极材料磷酸铁锂（LiFePO₄）的核心前驱体,FePO₄形貌及硫含量对合成的LiFePO₄材料性能有重要影响。为得到类球形低硫FePO₄产品,在传统液相沉淀法技术基础上做了改进优化,添加十六烷基三甲基溴化铵（CTAB）作为形貌助剂提高产品球形度,添加氨水作为配体形成磷酸铁铵配合物改善结晶过程,降低产品硫含量。结果表明：所制备的FePO₄产品硫质量分数低,达到2.6×10 ^-5,形貌为均一的微米类球形颗粒,D₅₀=11.4 μm,振实密度达到1.22 g/cm ³,有望成为制备高压实密度LiFePO₄材料的核心前驱体。     

涂碳铝箔对LiFePO4动力电池性能影响

分别以普通铝箔和涂碳铝箔为正极集流体制备磷酸铁锂（LiFePO₄）扣式电池（OB-1、OB-2）和全电池（FB-1、FB-2,批量生产）。采用扫描电子显微镜、X射线光电子能谱和电化学工作站对正极箔材和所组装的电池进行表征,并对其电化学性能进行研究,根据所组装电池在不同条件下的充放电性能判断涂碳铝箔对磷酸铁锂动力电池充放电性能的影响。结果表明,涂碳铝箔有利于提高Li⁺扩散速率和充放电性能。然而,涂碳铝箔对电池在低温环境中的充放电性能影响更大。以涂碳铝箔为集流体可以降低电池内阻,提高电池低温充放电性能。温度为-20℃时,OB-2中Li⁺扩散速率可达1.1×10^-12m²/s,放电容量为92.7mA·h/g,全电池FB-2循环充放电100次,容量保持率可达72.2%。