锂离子电池正极材料LiFePO4／C的合成及性能研究

以葡萄糖为碳源，利用高温固相法合成了橄榄石型LiFePO2／C。XRD结果表明葡萄糖的加入并没有改变LiFePO4的结构。SEM观察到C的包覆可以有效抑制颗粒的长大，且使颗粒形状更为规则。以合成材料为正极的锂离子电池的充放电测试结果表明，在0．1C的电流密度下，样品30的首次充放电容量达到1575mAin·g^-1,第三次容量达到164．9mAh·g^-1，接近理论容量，经过10次循环后，仍保持在161．7mAh·g^-1，循环性能稳定。循环伏安特性表明，在循环过程中，锂离子插入和脱出具有单一的可逆机制。     

大功率锂离子电池正极材料LiFePO4的研究进展

具有橄榄石结构的磷酸铁锂(LiFePO4)作为新兴的一种大动力锂离子电池的正极材料,具有安全性好、绿色环保、价格低廉、循环性能好、结构稳定等优点,是电动汽车、航天器以及大功率动力设备极其理想的高能电池正极材料.综述了LiFePO4作为正极材料的结构特点和充放电机理,以及电化学性能和近几年来优化改性的方法,并展望了LiFePO4正极材料的研究方向和应用方向.     

LiFePO4锂离子电池的数值模拟：正极材料颗粒粒径的影响

LiFePO₄（LFP）作为正极材料时,锂离子电池安全性高且循环寿命长,是目前应用最广泛的正极材料,但其电池倍率性能较差。提升倍率性能的有效手段之一是将LFP材料颗粒纳米化,但材料纳米化过程中颗粒粒径减小对于锂离子电池充放电过程中锂在固液相的扩散及表面电化学反应的影响机制仍缺乏清晰的认识。采用锂离子电池的准二维模型,模拟锂离子电池的放电过程,定量研究了正极材料颗粒粒径对锂离子电池倍率性能的影响,分析了固液相扩散速率与电化学反应速率受LFP材料颗粒粒径的影响程度。研究结果表明：电极材料中固相扩散阻力是锂离子电池电化学性能的主要限制因素。小粒径的LFP作为正极材料时,电极材料内的金属锂的迁移路径较短,同时颗粒与电解液的接触面积增加,界面的电化学反应速率较快,放电倍率对于锂离子电池性能影响较小;大粒径的LFP作为正极材料时,电极材料内的金属锂扩散路径的增加和较高的固相扩散阻力限制了界面的电化学反应速率,导致锂离子电池的倍率性能显著降低。LFP材料的纳米化可以有效减小固相扩散阻力,提升锂离子电池的倍率性能。     

锂离子电池正极材料LiFePO4的电化学性能改进

引言 随着社会的进步,人们对化学电源提出了高能量、长寿命、低成本、低环境污染的要求.虽然锂离子蓄电池目前已经实现了商品化,但正极嵌锂材料结构与性能的研究,以及如何提高容量和降低成本是锂离子蓄电池进一步被开发和应用的关键.     

废旧锂离子电池正极材料LiFePO4/C的电化学修复再生

将经过1500次循环的废旧LiFePO4电池正极材料进行回收处理后,与导电碳黑、聚偏氟乙烯(PVDF)黏结剂按质量比80：15：5混合均匀重新制成正极片。以金属锂片为负极与其组装成半电池,通过充放电过程让负极的锂补充到待修复正极材料LixFePO4/C (0相似文献   

锂离子电池正极材料LiFePO4的研究进展

LiFePO4作为新一代首选的正极材料,具有材料来源广泛、价格便宜、热稳定性好、比能量高、无吸湿性、对环境友好等优点。笔者综述了LiFePO4的结构特征、充放电机理、合成方法及改性研究。     

锂离子电池正极材料LiFeP04合成方法综述

LiFePO4是一种重要的锂离子电池正极材料。综述了几种常见的LiFePO4合成方法（主要包括固相法、微波法、碳热还原法、机械力化学活化法、水热法、溶胶凝胶法、液相沉淀法、微乳液干燥法、喷雾热解法等）及其特点,主要介绍近10年来国内外在此方向的重要研究成果及进展。     

锂离子电池正极材料LiFePO_4的研究进展

介绍了锂离子电池正极材料LiFePO4的结构特征和电化学过程。评述了近年来制备LiFePO4的各种方法,包括固相法,液相法(水热法、液相共沉淀法等),微波法等。橄榄石型磷酸铁锂(LiFePO4)理论比容量为170 mA.h/g,电压为3.5V(vs.Li/Li+),环境友好,成本低廉,热稳定性较好,可望成为锂离子蓄电池的新型正极材料。     

磷酸铁锂锂离子电池正极材料的研究

锂离子电池是绿色高能可充电池，具有工作电压高、比能量大、自放电小、循环寿命长、无记忆效应、无环境污染等突出优点。本文从磷酸铁锂的结构与性能、材料的制备方法、改性、粒径控制等几方面综述了近年来对橄榄石型磷酸铁锂（LiFePO4）锂离子电池正极材料的研究进展。材料的粒度大小及其分布、离子和电子的传导能力对产品的电化学性能影响很大。在制备时，采用惰性气氛、掺杂导电材料和控制晶粒生长制备粉体是获得性能优良的LiFePO4的有效方法。     

纳米LiMn2O4制备及电化学性能研究

以高能球磨后的MnO2为前躯体,用水热法成功合成了平均粒径为60nm的LiMn2O4纳米微粒。实验结果表明,所合成的纳LiMn2O4在0．2℃倍率放电条件下,首次放电比容量为122mAh／g,样品在经过20次循环后容量下降约为5％左右,表现出较好的电化学性能。     

Optimized synthesis of Cu-doped LiFePO4/C cathode material by an ethylene glycol assisted co-precipitation method

LiFePO₄/C and cupric ion doped LiFePO₄/C cathode materials were synthesized via an ethylene glycol assisted co-precipitation method. We assessed the influence of different parameters on electrochemical performance including calcination conditions, the amount of cupric ions added, doping ways, and drying methods. The microstructure of the materials was characterized by XRD, SEM, TEM, and EA. The results indicated the optimized Cu-doped LiFePO₄/C shows enhanced electrochemical performance with excellent high-rate capacity and cycle stability compared with LiFePO₄/C. The optimized Cu-doped LiFePO₄/C exhibited a high specific capacity of 148 mA h g⁻¹ at 0.1 C. Even at a rate of 10 C, it still achieved a specific capacity of 111 mA h g⁻¹ and its capacity retention ratio remained at 99.9% after 100 cycles at 1 C. These enhanced electrochemical properties were mainly due to a lesser extent of particle aggregation and more uniform carbon coating. Importantly, the synthesis process of this study is simple, fast, and economical thus it is promising to apply in industrialization.     

An investigation of polypyrrole-LiFePO4 composite cathode materials for lithium-ion batteries

A series of polypyrrole-LiFePO₄ (PPy-LiFePO₄) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO₄ particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO₄ electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO₄ composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO₄ composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO₄ electrode.     

Enhanced rate performance of nano–micro structured LiFePO4/C by improved process for high-power Li-ion batteries

A spherical carbon-coated nano–micro structured LiFePO₄ composite is synthesized for use as a cathode material in high-power lithium-ion batteries. The composites are synthesized through carbothermal reduction with two sessions of ball milling (before and after pre-sintering of precursor) followed by spray-drying with the dispersant of polyethylene glycol added. The structure, particle size, and surface morphology of the cathode active material and the properties of the coated carbon are investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Results indicate that the LiFePO₄/C composite has a spherical micro-porous morphology composed of a large number of carbon-coated nano-spheres linked together with an ordered olivine structure. The carbon on the surface of LiFePO₄ effectively reduces inter-particle agglomeration of the LiFePO₄ particles. A galvanostatic charge–discharge test indicates that the LiFePO₄/C composites exhibit initial discharge capacities of 155 mAh g⁻¹ and 88 mAh g⁻¹ at 0.2 C and 20 C rates with the end of discharge voltage of 2.5 V, respectively. This behavior is ascribed to the unique spherical structure, which shortens lithium ions diffusion length and improves the electric contact between LiFePO₄ particles.     

Rational design of mesoporous LiFePO4@C nanofibers as cathode materials for energy storage

In this work, the mesoporous LiFePO₄@C nanofibers have been successfully fabricated through a facile electrospinning method. The structure, morphology, chemical composition and lithium storage performance have been systematically investigated. The results reveal that the LiFePO₄ grains with particle size of ～15 nm are uniformly dispersed in the mesoporous carbon nanofibers. The LiFePO₄@C electrode presents a high reversible capacity and excellent rate performance. It delivers a discharge capacity of 107 mAh g⁻¹ and retains 105 mAh g⁻¹ over 200 cycles at 10C. The excellent electrochemical performances are attributed to the novel nanostructure where LiFePO₄ nanoparticles are embedded in the carbon fibers. This designed structure can significantly enhance the conductivity of LiFePO₄@C, accelerate the diffusion of electrolyte, and thus facilitate the transport of electrons and Li-ions.     

Investigation on diffusion behavior of Li in LiFePO4 by capacity intermittent titration technique (CITT)

Capacity intermittent titration technique (CITT) was used to investigate the chemical diffusion coefficient () of lithium-ion in LiFePO₄ cathode material. The values of at the galvano-charge current of 0.2 and 0.4 mA were respectively found to range from 8.8 × 10⁻¹⁶ to 8.9 × 10⁻¹⁴ cm² s⁻¹ and from 1.2 × 10⁻¹⁶ to 8.5 × 10⁻¹⁴ cm² s⁻¹ in the voltage range from 3.2 to 4 V (vs. Li⁺/Li). The transfer coefficients of cathode (0.32-0.42) and anodic (0.26-0.3), and the standard rate constant (1.58 × 10⁻⁹ to 1.30 × 10⁻⁸ cm s⁻¹) were measured from the Tafel plots of LiFePO₄ in the equilibrium potential range from 3.06 to 3.45 V. From these kinetic parameters, the finite kinetics at interface was taken into account to revise the above values of . The revised values of at the galvano-charge current of 0.2 and 0.4 mA were respectively found to range from 2.44 × 10⁻¹⁵ to 2.21 × 10⁻¹³ cm² s⁻¹ and from 5.81 × 10⁻¹⁶ to 3.22 × 10⁻¹³ cm² s⁻¹ in the voltage range from 3.2 to 4 V. Results show that the approximation of infinite charge-transfer kinetics leads to a spurious value of which is lower than the revised value, and the spurious extent depends on the galvano-charge current of CITT experiment.     

Mn~(2+)掺杂及碳包覆对磷酸亚铁锂的影响

以醋酸锰为Mn源,葡萄糖为C源,采用高温固相法合成磷酸亚铁锂,对磷酸亚铁锂进行了Fe位掺杂和表面的包覆碳研究。用XRD、恒流充放电研究了材料的结构和电化学性能。结果表明:掺杂及包覆后的材料仍然具有橄榄石型晶体结构,并且掺杂及包覆碳后材料的初始容量和循环性能都得到了改善,表现出了良好的循环性能和高倍率性能。     

Review on doping strategy in Li4Ti5O12 as an anode material for Lithium-ion batteries

Lithium-Ion Batteries (LIBs) as rechargeable energy storages play a key role in saving oil and decreasing exhaust emissions which are used for many applications including electric vehicles and electronic devices. Lithium titanate (LTO) as a promised anode material provides not only the Li-ion extraction and intercalation reversibility but also low volume changing during Li transmission. Nevertheless, LTO has some limitations which can be improved by some strategies such as doping. Dopants as a substation in the crystal structure of LTO could result in better performance in LIBs. In this report, doping of LTO with all kinds of dopants and with different fabrication methods is reviewed.