Performance degradation mechanism of lithium compounds ceramic fuel cell with GDC as electrolyte

The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.

Strategies of Removing Residual Lithium Compounds on the Surface of Ni-Rich Cathode Materials

Ni-rich cathode materials have become one of the most promising cathode materials for advanced high-energy Li-ion batteries(LIBs)owing to their high specific capacity.However,Ni-rich cathode materials are sensitive to the trace H2O and CO2 in the air,and tend to react with them to generate LiOH and Li2COg at the particle surface region(named residual lithium compounds,labeled as RLCs).The RLCs will deteriorate the comprehensive performances of Ni-rich cathode materials and make trouble in the subsequent manufacturing process of electrode,including causing low initial coulombic efficiency and poor storage property,bringing about potential safety hazards,and gelatinizing the electrode slurry.Therefore,it is of considerable significance to remove the RLCs.Researchers have done a lot of work on the corresponding field,such as exploring the formation mechanism and elimination methods.This paper investigates the origin of the surface residual lithium compounds on Ni-rich cathode materials,analyzes their adverse effects on the per-formance and the subsequent electrode production process,and summarizes various kinds of feasible methods for removing the RLCS.Finally,we propose a new research direction of eliminating the lithium residuals after comparing and summing up the above.We hope this work can provide a reference for alleviating the adverse effects of residual lithium compounds for Ni-rich cathode materials'industrial production.

Effect of chemical reactions between electrolyte and lithium compounds on the electrochemical performance of the ceramic fuel cells

Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Previous studies have pointed out that after being reduced by H2,NCAL anode will produce LiOH/Li2CO3 mixture and diffuse into the electrolyte,which results in the high ionic conductivity of the cell.In this study,the chemical reactivity of different oxide electrolytes such as CeO_(2),TiO_(2),ZrO_(2)and YSZ with LiOH and/or Li2CO3 and their effects on the electrochemical performance of the cell were studied.It is found that at 550◦C,only the open circuit voltage(OCV)of the cell using CeO_(2)as electrolyte can remain stable,and the maximum power density(MPD)of the CeO_(2)electrolyte cell reaches 599.6 mW⋅cm^(−2).The OCV of the cells with TiO_(2),ZrO_(2)and YSZ as electrolyte increased to the highest value within a few minutes,and the MPD of the cells was only more than 12 mW⋅cm^(−2).XRD,FT-IR,SEM-EDS and ICP-OES results indicate that the LiOH/Li2CO3 mixture diffuses into TiO_(2),ZrO_(2)and YSZ electrolytes and reacts with three oxides to produce Li2TiO3 and Li2ZrO3,respectively,which results in the low performance of the cell.

Lithium-ion-storage behaviours of CoSb_3 intermetallic compound and effects of some carbonaceous additives

Intermetallic compound CoSb 3 powders were prepared by vacuum melting and ball milling. It is found that the reversible capacity of the CoSb 3 electrode is about 470?mA·h/g at the first cycle with the potential plateaus from 0.8?V to 1.0?V against the pure lithium electrode. 10% mesocarbon microbead (MCMB) (mass fraction) additives can improve both capacity and cycling life of CoSb 3, while the effect of carbon nanotube (CNT) additives is not visible.

构建一维铜基配位聚合物作为锂离子电池正极材料

合成了一种新型的一维(1D)羰基配位聚合物[Cu(BGPD)(DMA)(H2O)]·DMA(记为Cu-BD,H2BGPD=N,N’-双(甘氨酰)均苯四甲酸二酰亚胺,DMA=二甲基乙酰胺),并考察了其用作锂离子电池正极材料的电化学性能。电化学测试结果表明,Cu-BD正极在50 mA·g^(-1)的电流密度下循环100圈后仍然保留50 mAh·g^(-1)的比容量,具有较好的循环稳定性。Cu-BD电极反应机理研究表明,BGPD2-配体和Cu(Ⅱ)离子在充放电过程中都可能参与了电子转移过程。

Electrochemical performance of a nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material for lithium-ion batteries under different cut-off voltages

A spherical-like Ni0.6Co0.2Mn0.2(OH)2precursor was tuned homogeneously to synthesize LiNi0.6Co0.2Mn0.2O2as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi0.6Co0.2Mn0.2O2were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge–discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi0.6Co0.2Mn0.2O2material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh•g−1at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh•g−1at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh•g−1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

熔盐法制备Co_(9)S_(8)/C锂离子电池负极材料及其性能研究

以氯化钴为钴源,硫脲为硫源,柠檬酸为碳源,冷冻干燥后,采用熔盐法在不同的温度进行退火处理得到Co_(9)S_(8)与C的复合物CS(CS-600,CS-700,CS-800,CS-900)。系统地探讨了不同的退火温度对产物的晶体结构、形貌及电化学性能的影响。结果发现:和纯Co_(9)S_(8)样品相比,碳复合的Co_(9)S_(8)样品的循环性能与倍率性能得到了较大的提升。在煅烧温度为700℃时,所合成的样品CS-700具有最高的比容量与最好的循环性能,在100 mA·g^(-1)充放电循环100次后,放电比容量可以达到898.6 mAh·g^(-1),可作为锂离子电池负极材料的潜在选择。

LiPF6 and lithium difluoro(oxalato)borate/ethylene carbonate+dimethyl carbonate+ethyl(methyl)carbonate electrolyte for LiNi0.5Mn1.5O4 cathode

LiODFB electrolyte’s compatibility with LiNi0.5Mn1.5O4high-voltage cathode material was studied by cyclic voltammetry, charge-discharge test and AC impedance. The results show that at 25 and 60 °C, the LiODFB-based electrolyte has better electrochemical stability than LiPF6. AC impedance plots show that the LiODFB battery has a lower charge-transfer resistance than LiPF6battery at 60 °C, which indicates that LiODFB battery has excellent cycling performance at high temperature. At 25 and 60 °C, the LiNi0.5Mn1.5O4/Li half cells with LiODFB or LiPF6as electrolyte all have simple redox peak, showing that each of them has an excellent reversibility. LiODFB battery has better cycle performance than LiPF6battery at 25 °C and 60 °C. At 25 °C, their 0.5C initial discharge specific capacities are 126.3 and 131.6 mA·h/g, and their capacity retention ratios of the 100th cycle are 97.1% and 94.7%, respectively. At 60 °C, their 0.5C initial discharge specific capacities are 132.6 and 129.1 mA·h/g, and their capacity retention ratios of the 100th cycle are 94.1% and 81.7%, respectively. © 2017, Central South University Press and Springer-Verlag GmbH Germany.

基于碳/MOFs及其衍生物复合材料在锂硫电池阴极中的应用

锂硫电池(lithium-sulfur batteries,LSBs)因其理论能量密度高、价格低廉而被认为是一种最具前景的新型电池体系之一。然而,实际应用中存在导电性差、体积易膨胀,以及循环稳定性差等问题。金属有机框架(metal organic frameworks,MOFs)因其高比表面积与孔隙率特性在LSBs中有效抑制硫溶解,提升硫利用率,实现高循环稳定性,而结合导电性优异的碳材料则进一步优化了整体导电性能。因此,基于碳/MOFs及其衍生物的复合物材料在LSBs阴极中的应用成为当前LSBs的研究热点。综述了近年来有关碳/MOFs及其衍生物的复合物材料在LSBs正极材料方面取得的一些研究进展,并对MOFs及其衍生物在LSBs电极中的应用进行了总结和展望。

国内磷酸二氢锂行业现状与展望

随着锂电新能源行业的飞速发展,我国磷酸二氢锂的市场需求量逐年攀升,而目前国内存在较大的产能缺口,并且工业化生产磷酸二氢锂的报道极其有限。因此对已报道的磷酸二氢锂生产工艺进行总结,并对近年国内磷酸二氢锂行业动态进行整理与汇总,最后对磷酸二氢锂行业未来发展趋势进行展望,旨在为磷酸二氢锂行业的发展提供参考与帮助。

诱变筛选Vc二步伴生菌

为了提高Vc二步发酵糖酸转化率,以巨大芽孢杆菌WS-05为出发菌株,采用微波和氯化锂复合诱变的方法进行诱变选育,筛选促进产酸菌生长和代谢的伴生菌。研究了微波-氯化锂诱变过程中不同的剂量、时间对Vc二步伴生菌存活率的影响,选取菌株存活率为55%~70%的3组诱变组合方式进行诱变,筛选能使小菌发酵产2-酮基-L-古龙酸产量高的伴生菌,经摇瓶发酵复筛,获得高产菌株D06,其转化率较出发菌株高2%。研究了发酵条件对新菌系的影响,结果显示:适当增加新菌系通气量(250 mL发酵摇瓶中装液20~25 mL)可以充分满足菌体代谢产酸对氧的要求,最适底糖浓度为7%,最适生长温度为31℃;经传代实验证明,其遗传性状稳定,4代平均转化率可达87.84%。

纳米纤维素基复合材料在锂硫电池中的应用研究进展

锂硫电池因具有高的理论比容量和能量密度,成为极具应用前景的下一代储能器件。纳米纤维素基材料因其独特的多孔网状结构和理化特性,在锂硫电池的开发研究中受到广泛关注。本文在简要介绍锂硫电池基本工作原理的基础上,分析了阻碍其商业化发展的问题和面临的挑战。针对纳米纤维素的独特结构和优异性能,重点综述了纳米纤维素基复合材料在锂硫电池中的最新研究进展,包括作为隔膜、阴极材料和其他组件等,有效缓解“穿梭效应”“体积膨胀”和“锂枝晶”等关键难题,明显提升了电池的电化学性能与使用寿命。此外,还介绍了纳米纤维素基复合材料在未来发展中亟待解决的问题,并对纤维素基锂硫电池器件的发展方向进行了展望。

锂离子电池铁基负极材料研究进展

铁基负极材料具有理论比容量高、反应电位低、环境友好等优势,成为锂离子电池领域的研究热点。然而,铁基负极材料在电池循环中存在体积膨胀大、离子/电子输运能力差等问题,较大地影响了铁基负极材料的广泛应用。基于这些问题,从纳米化构筑、碳材料复合和晶体结构调控等方面,综述了铁基负极材料的相关研究进展,以期为高性能铁基锂离子电池负极材料的研究和发展提供有效建议。

原生质体紫外-氯化锂复合诱变纳他霉素高产菌株的研究

本研究采用原生质体紫外-氯化锂复合诱变育种技术,以褐黄孢链霉菌为出发菌株,成功筛选出三株产纳他霉素能力较高且遗传稳定的突变菌株。实验发现,复合诱变最佳条件为氯化锂质量分数0.5%和紫外照射时间90 s,该条件下选出的三株产量较高的突变菌株,其摇瓶发酵液中纳他霉素平均产量为3 977 mg/L,较原始菌株提高32.5%。经连续五次传代后,突变菌株遗传性状稳定,且在300 L发酵罐中,SG-14突变菌株发酵液中纳他霉素产量最高,达4 176 mg/L,产量较出发菌株提升35.9%,周期缩短15 h。该育种技术显著提高生产菌发酵效率,对工业化生产和工艺改进具有重要价值。

钒基锂离子电池负极材料的研究进展与展望

综述了近年来钒基化合物(包括钒氧化物、钒酸盐、钒磷酸盐和无氧钒基化合物)在锂离子电池负极材料领域的研究进展,讨论并分析了相关负极材料的改性方法、材料结构与电化学性能的关系,提出了钒基锂离子电池负极材料未来研究重点。

构筑星形化合物提升交联网络固态聚合物电解质性能

通过巯基-丙烯酸酯点击反应引发三羟甲基丙烷三(3-巯基丙酸酯)(TMPMP)或季戊四醇四-3-巯基丙酸酯(PETMP)分别与聚(乙二醇)甲基丙烯酸酯(PEGMA)进行UV辐照反应,制得星型化合物。TMPMP或PETMP为交联剂,PEGMA为星形化合物的支链。星形化合物的结构可通过变换不同的交联剂,并通过改变PEGMA的相对分子质量进行调节。将星形化合物掺入交联固态聚合物电解质中,固态电解质的机械性能、电化学性能均得到改善。固态电解质的拉伸强度达83.9 MPa,杨氏模量达180.4 MPa,断裂伸长率达49.9%,拉伸韧性达22.6 MJ/m^(3),室温离子电导率达2.8×10^(-5) S/cm。利用该固态电解质组装Li/LFP全固态锂金属电池,在0.1 C倍率下循环100次后剩余比容量为111.5 mAh/g,比容量保持率为77%。

Enhanced thermoelectric performance in p-type Mg3Sb2 via lithium doping

The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.

Syntheses and Application of All-lithium Salts of Heteropolyacid as Electrolyte of Lithium-ion Battery

The all-lithium salts of heteropoly acid Li_xXM_ 12O_ 40(HPA-Li)(X=P, Si; M=Mo, W) were obtained via ion exchange and characterized by means of IR and UV spectroscopies, TG and elemental analyses. The conductivity of the electrolytic solution consisting of Li_3PW_ 12O_ 40 and PC/DME mixing solvent(1/2.5, volume ratio) is up to 7.2×10 -2 S/cm, being higher than that of LiClO_4 as the electrolyte. The all-lithium salts were used as electrolytes in secondary lithium-ion batteries. The discharge capacity of the PAS/Li batteries with Li_3PW_ 12O_ 40 electrolyte solutions reaches to 148 (mA·h)/g and the cyclic life is up to 380 times, much better than those of commercialized products with LiClO_4 and LiAsF_6 as electrolytes.

废旧锂离子电池热处理过程中污染物的迁移转化

电动汽车产业的发展带来锂离子电池需求大增,将会产生大量的废旧锂离子电池,回收废旧锂离子电池可以节约大量资源。热处理是锂离子电池回收工艺中的重要环节,但锂离子电池中的电解液、有机黏结剂和金属成分极易在加热过程中挥发从而污染环境,所以分析热处理过程中产生的污染物具有重要意义。以废旧三元锂离子电池为原材料,分别在100、200、300、400、500、600℃和惰性气氛条件下加热,保温时间60 min,氮气流量500 mL/min,升温速率10℃/min。采用TG-MS、XRD、SEM、ICP-AES、GC-MS等表征和分析产物。结果表明,金属挥发率随着温度的升高而增加,但是总体挥发率不超过1%;电解液会发生分解和挥发行为,分解产物主要是CO_(2)、H_(2)O和小分子烷烃;LiPF_(6)分解产生氟化物,PVDF和隔膜的分解产生有机污染物;挥发的氟化物随着温度的升高而增加,产生的有机气体可以作为原料进行回收,且热解后的材料更有利于回收。