导电Ti_3O_5包覆纳米铝粉的制备及其作为双离子电池负极材料的电化学性能（英文）

采用导电的Ti_3O_5作为外壳包覆纳米铝粉制备了Al@Ti_3O_5核壳结构材料,并将其作为负极材料应用到双离子电池(DIB)中。使用中间相碳微球(MCMB)作为正极材料,Al@Ti_3O_5作为负极材料制作Al@Ti_3O_5-MCMB双离子电池。结果表明,电池的放电平台可达4.5 V,在电流倍率0.5 C下(电流基于正极石墨的理论比容量计算,1 C=372 mAh·g~(-1))放电比容量达到130.6 mAh·g~(-1),比能量密度为278.8 Wh·kg~(-1)。并且在高倍率5 C下循环1000次过程中容量基本保持110 m Ah·g~(-1)不变,循环后容量保持率达到92.9%。     

Cr3+掺杂LiNi0.5Mn1.5O4材料的制备及性能研究

采用高温固相法合成了Cr₃₊掺杂的LiNi_0.5Mn_1.5O₄正极材料,研究了掺杂量对材料物理性能和电化学性能的影响。利用XRD、SEM对材料的结构和形貌进行了表征,结果显示样品具有棱边清晰的尖晶石形貌。讨论了不同Cr₃₊掺杂量对LiCr_xNi_0.5-0.5xMn_1.5-0.5xO₄(x=0,0.05,0.1,0.15,0.2)正极材料性能的影响。充放电测试、循环伏安和交流阻抗测试结果表明：当Cr₃₊的掺杂量为x=0.1时(LiCr_0.1Ni_0.45Mn_1.45O₄)正极材料的性能最好,0.1C、0.5C、1C、2C及5C的首次放电比容量依次为131.54mAh g_-1、126.84mAh g_-1、121.28mAh g_-1、116.49mAh g_-1和96.82mAh g_-1,1C倍率下循环50次,容量保持率仍为96.5%。     

非水体系中钒酸锂/聚吡咯复合正极材料的制备及性能研究

采用乙醇作为介质,FeCl₃为氧化剂,对甲苯磺酸钠为掺杂剂,通过吡咯单体在钒酸锂表面的氧化聚合制备出了钒酸锂/聚吡咯(LiV₃O₈/PPy)复合材料。采用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)对复合材料的结构与形貌进行表征。用恒流充放电测试、循环伏安(CV)和交流阻抗(EIS)等研究了聚吡咯包覆量对材料电化学性能的影响。结果表明：在钒酸锂表面均匀地包覆了一层厚度约10nm的聚吡咯,但并没有改变钒酸锂的晶型结构。当聚吡咯包覆量为6% 时,复合材料的电化学性能最好,在0.1C充放电倍率下,首次放电比容量为274mAh/g,循环100次后样品的放电比容量为239.4mAh/g,容量保持率为87.4%,而未包覆PPy的LiV₃O₈,其首次放电比容量为227.4mAh/g,循环100次后样品的放电比容量为160.1mAh/g,容量保持率仅为70.4%。LiV₃O₈/PPy复合正极材料的电化学性能得到了明显提高。     

不同锂源对高温固相法制备NCM811正极材料储锂性能的影响

采用4种不同的锂盐(LiOH.H₂O、Li₂CO₃、LiNO₃、CH₃COOLi),以高温固相法制备了LiNi_0.8Co_0.1Mn_0.1O₂正极材料。利用X射线粉末衍射(XRD)和场发射电子显微镜(FESEM)对所制LiNi_0.8Co_0.1Mn_0.1O₂材料的微观结构进行了表征,发现所有合成的LiNi_0.8Co_0.1Mn_0.1O₂样品尺寸均为微米级大小,具有层状结构(R-3m空间群)。电化学测试结果表明采用不同锂源制备的LiNi_0.8Co_0.1Mn_0.1O₂样品的电化学性能差别很大。其中采用LiOH?H₂O为锂源,经500 °C预烧结6 h后,在800 °C下烧结16 h获得的样品锂镍混排程度最低,电化学性能最佳。例如,在0.1 C(1 C=180 mA/g)倍率下其可逆比容量高达206.2 mA.h/g,在10 C大倍率下,其可逆比容量仍保持有80.9 mA.h/g;在0.5 C倍率下100次充放电循环过程中,最高放电比容量为176.2 mA.h/g,平均放电比容量为140.1 mA.h/g。动力学及电极稳定性分析发现,LiOH?H₂O制备的样品的电化学可逆性最好,Li^₊扩散系数最大,充放电循环过程中结构稳定性最好。     

微波原位制备作为锂离子电池电极材料的石墨烯/TiO2 纳米复合物

通过改造的家用微波炉,实现了原位高效制备石墨烯/TiO₂纳米复合物。结果表明：微波辅助法能够在商用锐钛矿型TiO₂纳米颗粒表面均匀制备石墨烯纳米片,通过SiO₂/Si的剧烈电晕放电,其制备时间仅需数分钟（最短3 min）。石墨烯纳米片的尺寸大约为50 nm且缺陷很少。TiO₂晶体结构仍为锐钛矿型,主要归功于极短的制备周期和较低的反应温度（600~700 ℃）。石墨烯具有优异的电导率,可以提升锂离子扩散速率、提高电子传输速率并降低接触电阻。在1 C（170 mA·g^-1）条件下石墨烯/TiO₂纳米复合物的电池放电比容量提高了2倍。与商业化锐钛矿型TiO₂纳米颗粒相比,在1 C到5 C的不同充放电倍率下,石墨烯/TiO₂纳米复合物的比容量差距显著扩大。     

基于第一性原理的石榴石型Li7La3Zr2O12 固态电解质的设计与合成

基于密度泛函理论（DFT）的第一原理方法计算了四方相和立方相中2种不同的Li₇La₃Zr₂O₁₂（LLZO）固体电解质材料的能带结构,晶格参数,态密度和成键特性。基于理论计算结果,通过电子结构特性解释了四面体相的离子电导率低于立方相的离子电导率的原因。基于LLZO的第一性原理计算,设计了2种晶体结构的LLZO材料,并通过高温固相法制备并分析了不同烧结时间的LLZO颗粒的性能。探索了合成工艺参数对Li₇La₃Zr₂O₁₂性能的影响。立方晶Li₇La₃Zr₂O₁₂（C-LLZO）的平均晶格大小为a=b=c=1.302 246 nm,而四方Li₇La₃Zr₂O₁₂（T-LLZO）的平均晶格大小为a=b=1.313 064 nm,c=1.266 024 nm。在1000 ℃下烧结12 h的C-LLZO为纯立方相,在室温（25 ℃）下最大离子电导率为9.8×10^-5 S·cm^-1。T-LLZO在室温（25 ℃）下的离子电导率为5.96×10^-8 S·cm^-1,在800 ℃下烧结6 h具有纯的四方相结构,与计算结果基本吻合。     

定-转子反应器制备LiFe1-xMxPO4 (M= Mn, Ni)粉体及其性能研究

采用具有高效传质和微观混合性能的定-转子反应器制备了LiFe_1-xMn_xPO₄ (x=0.0, 0.1, 0.2, 0.3)和LiFe_1-xNi_xPO₄ (x=0.00, 0.03, 0.05, 0.07)粉体,分别用作正极材料制成电池后,采用电池测试系统测定了电池的电化学性能随温度的变化规律。结果表明,粉体颗粒呈类球形,尺寸分布均匀,粒径范围为5~10 μm,Mn和Ni的掺杂没有改变粉体的晶体结构。以LiFe_0.8Mn_0.2PO₄和LiFe_0.95Ni_0.05PO₄两种组成的粉体性能最好,在倍率0.1 C下,所得电池的首次充放电比容量在室温和50 _oC时,分别为153.2和155.7 mAh/g,及156.4和160.4 mAh/g;100次充放电循环后电池的容量保持率分别为95.4和96.5%,及93.8和95.0%。借助具有过程强化作用的定-转子反应器制备的Mn和Ni掺杂LiFePO₄正极材料的电性能得到显著提高。原因是定-转子反应器一方面可以制备颗粒尺寸均匀的粉体,另一方面又可使掺杂的Mn和Ni在粉体颗粒中均匀分布,两者同时提高了电池中Li₊的扩散速率,进而提高了锂离子电池的电化学性能和高温电性能。     

锂离子电池正极材料LiCoO2-LiFePO4的性能

研究用LiCoO2-LiFePO4作正极的锂离子电池的电化学性能和安全性能。结果表明:电池在1、3和5C倍率的放电容量分别为347.7、327.2和322.5 mA.h,5C条件下的放电容量为1C放电容量的92.8%。在25℃、1C条件下循环150次的容量保持率为100%;在?10℃、1C条件下的放电容量为256.5 mA.h,是25℃、1C放电容量的74.8%。电池具有很好的耐过充性能,在3C、10 V条件下进行过充电,电池不漏液、起火或爆炸。短路时电池的表面温度低于LiCoO2电池的表面温度。     

丝网印刷氧化石墨烯对锂离子电池LiNi1/3Co1/3Mn1/3O2 三元正极的改性及性能影响

通过丝网印刷方法,在由LiNi_1/3Co_1/3Mn_1/3O₂、导电添加剂和聚偏氟乙烯制成的电极表面涂覆了一层薄薄的氧化石墨烯。在充电截止电压为4.3 V的条件下进行了循环性能和倍率性能测试。结果表明：未改性电极在恒电流充放电测试中容量下降且极化增加,而包覆改性后电极的容量衰减程度和极化增加速度降低。这是由于氧化石墨烯涂层抑制了LiNi_1/3Co_1/3Mn_1/3O₂电极和电解质之间的部分副反应,使得改性电极的循环稳定性和倍率性能显著提高,为提升LiNi_1/3Co_1/3Mn_1/3O₂电极性能提供了一种环境友好且非常有效的方法。     

高容量锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的制备与工艺优化

采用氢氧化物共沉淀法合成前驱体Ni_0.5Cc_0.2Mn_0.3H(OH)₂,进一步用高温固相法与锂源共混煅烧得到LiNi_0.5Co_0.2Mn_0.3O₂。初步探讨了前驱体与锂源在高温煅烧过程中的质量变化及煅烧工艺对材料结构和性能的影响。热重分析(TGA)表明在煅烧过程中750℃后材料质量几乎没有变化。X射线衍射(XRD)对750℃-900℃的材料进行结构分析,结果表明所有材料具有良好的α-NaFeO₂层状结构和较小的阳离子混排度。扫描电镜(SEM)分析表明材料具有表面光滑,分布均匀的球形结构。横流充放电测试结果表明在850℃煅烧的材料具有最好的电学性能,在0.2C,2.5-4.6V测试条件下,其具有193.7mAh/g的首次放电容量,循环30次后的容量保持率为94.2%,并且具有最好的倍率性能。     

Synthesis of nano-sized Co<Subscript>3</Subscript>O<Subscript>4</Subscript> powder by spray conversion method for anode material of lithium battery

A nano-sized Co₃O₄ powder was prepared using a spray conversion method that could be applied for mass production. The spray-conversion process consisted of spray drying of a metallic liquid solution, a calcination treatment, and a ball milling process. The calcined Co₃O₄ powder consisted of agglomerated spherical clusters with nano-sized particles. After milling for 24 h, agglomerated powders were fragmented into fine powders sized below 60 nm. The lithium/cobalt oxide cell was charge-discharged at a constant current density of 0.2 mAcm⁻² and showed a first discharge capacity of 1100 mAhg⁻¹. The discharge capacity of the Li/Co₃O₄ cell drastically decreased with cycle number. By increasing the carbon content of the anode, the cycle life was improved. For a Co₃O₄ electrode containing 40 wt.% carbon, the discharge capacity was over 400 mAhg⁻¹ after 50 cycles. The spray conversion method might be a useful method to prepare nano-sized Co₃O₄ powder for the anode material of lithium batteries.     

Porous Li4Ti5O12 anode material synthesized by one-step solid state method for electrochemical properties enhancement

A porous Li₄Ti₅O₁₂ anode material was successfully synthesized from mixture of LiCl and TiCl₄ with 70 wt% oxalic acid by a modified one-step solid state method. The anode material Li₄Ti₅O₁₂ exhibited a cubic spinel structure and only one voltage plateau occurred around 1.5 V. The initial capacity of porous Li₄Ti₅O₁₂ was 167 and 133 mAh g⁻¹ at 0.5 and 1C charge/discharge rate, respectively, and the capacity retention maintained above 98% after 200 cycles. The porous Li₄Ti₅O₁₂ structure showed promising rate performance with a capacity of 70 mAh g⁻¹ at charge/discharge 10C rate after 200 cycles. It was demonstrated that the porous structure could withstand 50C charge/discharge rate and exhibited excellent cycling stability.     

Structure and electrochemical performance of FeF3/V2O5 composite cathode material for lithium-ion battery

Orthorhombic structure FeF₃ was synthesized by a liquid-phase method using FeCl₃, NaOH and HF solution as starting materials, and the FeF₃/V₂O₅ composites were prepared by milling the mixture of as-prepared FeF₃ and the conductive V₂O₅ powder. The properties of FeF₃/V₂O₅ composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge/discharge and cyclic voltammetry measurements. Results showed that the FeF₃/V₂O₅ composites can be used as cathode material for lithium-ion battery. Electrochemical measurements in a voltage range of 2.0–4.5 V reveal that the addition of conductive V₂O₅ improves significantly the electrochemical performance of FeF₃, and the FeF₃/V₂O₅ composite prepared by milling for 3 h exhibits high discharge capacity and good cycle performance, and its discharge capacity maintains about 209 mAh g⁻¹ at 0.1 C (23.7 mA g⁻¹) after 30 cycles.     

Improved capacity and rate capability of Ru-doped and carbon-coated Li4Ti5O12 anode material

Pure Li₄Ti₅O₁₂, modified Li₄Ti₅O₁₂/C, Li₄Ru_0.01Ti_4.99O₁₂ and Li₄Ru_0.01Ti_4.99O₁₂/C were successfully prepared by a modified solid-state method and its electrochemical properties were investigated. From the XRD patterns, the added sugar or doped Ru did not affect the spinel structure. The results of electrochemical properties revealed that Li₄Ru_0.01Ti_4.99O₁₂/C showed 120 and 110 mAh/g at 5 and 10 C rate after 100 charge/discharge cycles. Li₄Ru_0.01Ti_4.99O₁₂/C exhibited the best rate capability and the highest capacity at 5 and 10 C charge/discharge rate owing to the increase of electronic conductivity and the reduction of interface resistance between particles of Li₄Ti₅O₁₂.It is expected that the Li₄Ru_0.01Ti_4.99O₁₂/C will be a promising anode material to be used in high-rate lithium ion battery.     

Low temperature synthesis of Fe3O4 micro-spheres and its application in lithium ion battery

Fe₃O₄ micro-spheres with nanoparticles close-packed architectures were synthesized via a simple chemical method using (NH₄)₂Fe(SO₄)₂·6H₂O, hexamethylenetetramine, and NaF as reaction materials. This chemical synthesis took place in a vitreous jar under low temperature (90 °C) and atmospheric pressure. The morphology and structure of the as-synthesized products were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Raman spectrum. Electrochemical properties of the as-synthesized Fe₃O₄ micro-spheres as anode electrode of lithium ion batteries were studied by conventional charge/discharge tests, which exhibit steady charge/discharge platforms at different current densities. The as-prepared Fe₃O₄ electrode shows high initial discharge capacity of 1166 and 1082 mAh g⁻¹ at current density of 0.05 and 0.1 mA cm⁻², respectively.     

Synthesis and characterization of Al2O3-Ce0.5Zr0.5O2 powders prepared by chemical coprecipitation method

Al₂O₃-Ce_0.5Zr_0.5O₂ catalytic powders were synthesized by the coprecipitation (ACZ-C) and mechanical mixing (ACZ-M) methods, respectively. As-synthesized powders were characterized by XRD, Raman spectroscopy, surface area and thermogravimetric analyses. It was found that the mixing extent of Al³⁺ ions affected the phase development, texture and oxygen storage capacity (OSC) of the Ce_0.5Zr_0.5O₂ powder. Single phase of ACZ-C could be maintained without phase separation and inhibit α-Al₂O₃ formation up to 1200 °C. The specific surface area value of ACZ-C (81.5 m²/g) was larger than that of ACZ-M (62.1 m²/g) and Ce_0.5Zr_0.5O₂ (17.1 m²/g) powders, which were calcined at 1000 °C. In comparison with ACZ-C and Al₂O₃, which were calcined at high temperature (900–1200 °C), it was found that the degradation rate of specific surface area of ACZ-C was lower than that of Al₂O₃. ACZ-C sample showed a higher thermal stability to resist phase separation and crystallite growth, which enhanced the oxygen storage capacity property for Ce_0.5Zr_0.5O₂ powders.     

Synthesis and electrochemical properties of porous LiV3O8 as cathode materials for lithium-ion batteries

In this paper, we report on the synthesis of porous LiV₃O₈ by using a tartaric acid-assisted sol-gel process and their enhanced electrochemical properties for reversible lithium storage. The crystal structure, morphology and pore texture of the as-synthesized samples are characterized by means of XRD, SEM, TEM/HRTEM and N₂ adsorption/desorption measurements. The results show that the tartaric acid plays a pore-making function and the calcination temperature is an important influential factor to the pore texture. In particular, the porous LiV₃O₈ calcined at 300 °C (LiV₃O₈-300) exhibits hierarchical porous structure with high surface area of 152.4 m² g⁻¹. The electrochemical performance of the as-prepared porous LiV₃O₈ as cathode materials for lithium ion batteries is investigated by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy. The porous LiV₃O₈-300 displays a maximum discharge capacity of 320 mAh g⁻¹ and remains 96.3% of its initial discharge capacity after 50 charge/discharge cycles at the current density of 40 mA g⁻¹ due to the enhanced charge transfer kinetics with a low apparent activity energy of 35.2 kJ mol⁻¹, suggesting its promising application as the cathode material of Li-ion batteries.     

Synthesis and electrochemical performance of Li(Ni0.8Co0.15Al0.05)0.8(Ni0.5Mn0.5)0.2O2 with core-shell structure as cathode material for Li-ion batteries

The core-shell structure cathode material Li(Ni_0.8Co_0.15Al_0.05)_0.8(Ni_0.5Mn_0.5)_0.2O₂ (LNCANMO) was synthesized via a co-precipitation method. Its applicability as a cathode material for lithium ion batteries was investigated. The core-shell particle consists of LiNi_0.8Co_0.15Al_0.05O₂ (LNCAO) as the core and a LiNi_0.5Mn_0.5O₂ as the shell. The thickness of the LiNi_0.5Mn_0.5O₂ layer is approximately 1.25 μm, as estimated by field emission scanning electron microscopy (FE-SEM). The cycling behavior between 2.8 and 4.3 V at a current rate of 18 mA g⁻¹ shows a reversible capacity of about 195 mAh g⁻¹ with little capacity loss after 50 cycles. High-rate capability testing shows that even at a rate of 5 C, a stable capacity of approximately 127 mAh g⁻¹ is retained. In contrast, the capacity of LNCAO rapidly decreases in cyclic and high rate tests. The observed higher current rate capability and cycle stability of LNCANMO can be attributed to the lower impedance including charge transfer resistance and surface film resistance. Differential scanning calorimetry (DSC) indicates that LNCANMO had a much improved oxygen evolution onset temperature of approximately 251 °C, and a much lower level of exothermic-heat release compared to LNCAO. The improved thermal stability of the LNCANMO can be ascribed to the thermally stable outer shell of LiNi_0.5Mn_0.5O₂, which suppresses oxygen release from the host lattice and not directly come into contact with the electrolyte solution. In particular, LNCANMO is shown to exhibit improved electrochemical performance and is a safe material for use as an electrode for lithium ion batteries.     

Investigations on Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript>/Ti<Subscript>3</Subscript>O<Subscript>5</Subscript> Composite as an Anode Material for Lithium–Ion Batteries

The Ti₃O₅ powder with uniform morphology has been successfully obtained and used to synthesize Li₄Ti₅O₁₂/Ti₃O₅ composite material by ball milling for modifying Li₄Ti₅O₁₂-based, lithium–ion battery anodes. Moreover, according to the relative performance investigations, the synthesized Li₄Ti₅O₁₂/Ti₃O₅ composite shows better electrochemical properties than that of the Li₄Ti₅O₁₂. At a high rate (10 C), the capacity of the Li₄Ti₅O₁₂/Ti₃O₅ composite electrode is 139.8 mAhg^?1, whereas the value of Li₄Ti₅O₁₂ is 121.6 mAhg^?1, showing a capacity enhanced about 14.97%. After 100 cycles at 0.2 C, the discharge capacity of Li₄Ti₅O₁₂/Ti₃O₅ remains at 160 mAhg^?1 with a capacity loss of 2.6%. The results indicate that the Li₄Ti₅O₁₂/Ti₃O₅ composite electrode can be used as anode material with a relatively higher rate capability and excellent cycle performance in lithium–ion batteries.