Study on mineral structural stability of marine 1nm manganate

In order to study the phase transformation between 1nm manganate and 0.7nm manganate, a series of Slum Me^(2+) manganates were made after the synthetic 1nm Na^+ manganate substituted with different kinds of divalent cations. The X-ray diffraction analysis of wet S1nm Me^(2+) manganates after 24 h room temperature dry showed that their basal d-spacing had been changed, indicating that there was phase transformation between 1nm and 0.7nm manganates. Take 1nm manganates with unstable structure collapsed into 0. 7nm manganate by losing one interlayer OH-H_2O, while those with stable structure still retained the 1nm d-spacing. This factor reminds us that the manganese nodule samples must be kept in wet condition to avoid the misleading results. The structural stabdity of 1nn manganate is mainly controlled by the interlayer divalent cations. There is a possitive correlation between the amount of cations in the interlayer and the structural stability, while the capacity of different canons in stabilizing the structure of 1nm manganate is as follows: Ni > Cu > Co > Zn > Ca>Mg > Na.

Subacute toxicity of exogenous manganese on rat hippocampal neurons Examination by MRI and optical microscopy

BACKGROUND： Manganism may cause learning and memory impairment by influencing the normal function of the hippocampus, however, this effect requires further examination. OBJECTIVE： To investigate the effects of manganism on the rat hippocampus using immunohistochemistry and MRI examination. DESIGN, TIME AND SETTING： A randomized controlled study, performed in the School of Medicine and Life Science, Jianghan University and the State Key Laboratory of Atomic ＆ Molecular Physics and Spectroscopy, Chinese Academy of Science, from July to September 2005. MATERIALS： Fourteen healthy SD rats aged two months were selected for this study. MnCl2 4H2O （BHD, UK） （batch number： 9791325）; glial fibrillary acidic protein （GFAP） staining kit （Beijing Zhongshan Biotechnology）; Biospec 4.7T/30 animal MRI formatter （Bruker, Germany）. METHODS： Fourteen rats were randomly divided into a control group （n =7） and a manganism group （n = 7）. Rats in the manganism group received intraperitoneal injection of MnCl2 · 4H2O （50 mg/kg）, once a day, for four successive days. Rats in the control group were injected according to the manganism regimen, but using saline instead of manganese solution. MAIN OUTCOME MEASURES： Twenty-four hours after the last injection, rats were examined using MRI. Immunohistochemically stained GFAP and hematoxylin-eosin stained hippocampal sections were observed under optical microscopy. RESULTS： Fourteen rats were included in the final analysis. After manganese treatment, T1 weighted image and inversion recovery MR1 demonstrated that the signal intensity was significantly enhanced in hippocampus, compared to controls. Neuronal necrosis was not observed in the hippocampus after HE staining. As compared to the control group, GFAP expression was markedly enhanced in the hippocampus of the manganism group. CONCLUSION： Within the rat brain, manganese preferentially localizes to the hippocampus and can induce astroctye activation.

Synthesis and Biodegradation of St-g-poly(MMA-co-VAc) Initiated by Manganic Pyrophosphate

Methyl methacrylate(MMA) and vinyl acetate(VAc) were grafted onto corn starch with manganic pyrophosphate{[Mn(H 2P 2O 7) 3] 3-} as the initiator and water as the reaction medium. The influences of reaction conditions, including pH value, initiator concentration, monomer concentration and its composition, on percent grafting and grafting efficiency were investigated. The graft copolymer was characterized by means of IR spectroscopy, scanning electron micrograph(SEM) and 1H NMR spectroscopy. The biodegradation experiment showed that the degradation of corn starch-g-poly(MMA-co-VAc) was mainly from starch. However, after poly VAc in the side chain was transformed into poly vinyl alcohol(PVA), both starch and the grafted side chain could be degraded completely.

Study on the cation substitution capacity of synthetic 1nm manganate

Synthetic Ium manganate has been made in the laboratory at low temperature. The d-spaciug of which shows 1. 002 nm, 0. 501 nm and 0. 34 nm respectively. As the analogue of natural 1nm manganate, it has been used for a serieS of experiments of divalent cations substitution. The results indicate that the 1nm manganate has very strong cation substitution capacity, which probable is the reason of the valuable metal such as Cu, Ni and Co enriched in the manganese nodules. The preference of canons substituting into S 1nm manganate is Cu>Co>Zn≥Ni>Ca>Mg. In the manganese nodules, the content of Ni is usually higher than that of Cu and Co, but in the cation substitution, the latter two are more preference than the former. One can infer from this differentiation that the post-deposition cation substitution is not the sole mechanism by which the valuable metals enter the manganese nodules. It could be the results of combined effects of both original formation and the post-deposition substitution of canons,which leads to the enrichment of valuable metal in the manganese nodules.

Mitigating the Jahn-Teller distortion driven by the spin-orbit coupling of lithium manganate cathode

Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is predominately plagued by its severe capacity degradation,mainly associated with the innate Jahn-Teller effect.Herein,single-crystalline LiMn_(2)O_(4)with Eu^(3+) doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO_(6) octahedra and accommodating localized electron,based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions.Notably,the stretching of MnO_(6) octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn_(2)O_(4)is effectively suppressed,confirmed by theoretical calculation.Meanwhile,the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition,proved by synchrotron radiation absorption spectrum and operando X-ray diffraction.The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011%capacity drop per cycle even at 5C.Given this,this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.

难选高铁软锰矿流态化磁化焙烧-磁选浸出工艺

【目的】提高难选高铁软锰矿的资源利用效率,缓解我国锰矿资源依赖进口的现状。【方法】采用流化床反应器作为焙烧装置,模拟发生炉煤气气体组分作为还原气体,对云南省某地区的难选高铁软锰矿进行流态化磁化焙烧。对还原后的焙烧矿进行磨矿-弱磁磁选,得到铁精矿和锰精矿。最后,对锰精矿中的锰进行酸浸浸出。【结果】在500℃流态化还原焙烧10 min,该难选高铁软锰矿即可达到最佳的还原状态效果,当样品的磨矿粒径<30μm的颗粒的质量分数为65%时,即可达到最佳的解离效果。选别后铁精矿铁品位和回收率分别为57.24%和76.55%,锰精矿锰品位和回收率分别为24.41%和73.84%,锰精矿的铁浸出率仅有1.94%。【结论】考察难选高铁软锰矿流态化磁化焙烧-磁选浸出规律,可以降低反应温度,缩短反应时间,低碳节能;抑制过还原反应的发生,可以提高铁资源利用率,降低浸出酸耗和除铁剂消耗。低能耗、低消耗和高利用率可以极大地提高难选高铁软锰矿的经济性,解决这部分资源难于利用的困境。

石墨烯生产废液中双球状碳酸锰的提取及其电化学储锂性能

根据“双碳”目标和循环经济的要求,废弃物务必应收尽收。鉴于此,以Na2CO_(3)为沉淀剂,通过一步化学沉淀反应从石墨烯生产废液中提取了淡黄色MnCO_(3)粉末,并研究其电化学储锂性能。结果表明,废液中Mn离子的去除率为99.9%,MnCO_(3)粉末的回收率为92.6%。MnCO_(3)粉末由0.5~1.5μm的双球状颗粒组成,属于六方晶系;MnCO_(3)负极在0.5 A/g和1.0 A/g分别循环300圈后,其可逆放电容量分别为570 mAh/g和418 mAh/g。本文的研究结果为回收石墨烯工业废水提供了新思路,有助于降低环境污染排放。

Core level excitation spectra of La and Mn ions in LaMnO3

Manganese-based perovskite is popular for research on ferromagnetic materials,and its spectroscopic studies are essential for understanding its electronic structure,dielectric,electrical,and magnetic properties.In this paper,the M-edge spectra of La ions and the M-edge,L-edge,and K-edge spectra of Mn ions in LaMnO3 are calculated by considering both the free-ion multiplet calculation and the crystal field effects.We analyze spectral shapes,identify peak origins,and estimate the oxidation states of La and Mn ions in LaMnO3 theoretically.It is concluded that La ions in LaMnO3 predominantly exist in the trivalent state,while Mn ions exist primarily in the trivalent state with a minor presence of tetravalent ions.Furthermore,the calculated spectra are in better conformity with the experimental spectra when the proportion of Mn3+is 90%and Mn4+is 10%.This article enhances our comprehension of the oxidation states of La and Mn within the crystal and also provides a valuable guidance for spectroscopic investigations of other manganates.

废旧锂电池电极材料浮选行为及表面性质

锂离子电池中含有丰富的金属元素和多种毒害性物质,废旧锂电池回收不仅能实现资源循环利用,而且能防止环境污染.本文以废旧动力锰酸锂电池为研究对象,利用“焙烧强化浮选”的方法解决锰酸锂电池资源化回收过程中正负极电极材料难以浮选分离的问题,即通过焙烧去除电极材料表面的有机粘附物,从而增大电极材料表面润湿性差异,进而强化浮选分离过程.结果表明,商品化锰酸锂和商品化石墨具有相反的浮选行为,而废旧锰酸锂和废旧石墨具有相似的疏水性浮选行为.废旧锰酸锂电极材料浮选分离时,锰酸锂和石墨浮选分离效率低,而商品化锰酸锂和石墨的浮选分离效率高.XRD、XPS、SEM、FT-IR及接触角分析表明,废旧锂电池电极材料表面均包裹一层含C、O、F等元素的有机物,导致正负极电极材料具有相似的表面性质,因而表现出相似的浮选行为,导致两者的浮选分离难度大.不同焙烧参数下电极材料的浮选分离试验结果表明,550℃焙烧2 h后锰酸锂和石墨的浮选分离效率明显优于未焙烧的电极材料.此时,浮选精矿中锰酸锂的品位由未焙烧的63.10%提高到90.98%;小型闭路浮选精矿中石墨残留量少,锰酸锂的纯度达到99%.

含钒四氯化钛精制尾渣锰化焙烧制备V_(2)O_5工艺研究

为探究含钒四氯化钛精制尾渣中钒资源的提取利用可行性,在锰化焙烧提钒过程热力学分析的基础上,采用尾渣水洗预处理—锰化焙烧—草酸浸出—铵盐沉钒的工艺,重点研究了水洗液固比、焙烧温度、碳酸锰添加量对焙烧熟料物相组成和钒浸出率的影响规律。结果表明:粗Ti Cl_4含钒尾渣采用水洗的预处理方式,可有效降低尾渣中氯的含量,保障后续的铵盐沉钒,提高钒产品品位;适当提高焙烧温度和碳酸锰添加量有助于低价的钒与锰盐生成可溶性焦钒酸锰(Mn_(2)V_(2)O_7),但焙烧温度超过850℃和碳酸锰添加量大于2.0时,将导致含钒物相被硅酸盐等液相产物包裹,致使钒浸出率降低。试验适宜条件为:水洗液固比10m L/g,碳酸锰添加量(以n(MnO)/n(V_(2)O_5)计)2.0、焙烧时间2h、焙烧温度850℃,浸出时间30min、浸出温度50℃。上述条件下钒浸出率达82.16%,且浸出液经铵盐沉钒—焙烧工序后可得到纯度大于99%的粉状五氧化二钒产品。该工艺实现了含钒四氯化钛精制尾渣中钒的高效提取和分离,研究结果对该类型尾渣提钒具有指导意义。

氧化锂基复合正极补锂材料的制备及对电池电化学性能的影响

锂离子电池在首次充放电过程中,其负极表面形成的固态电解质界面(SEI)膜会消耗部分正极材料的活性锂,导致不可逆的容量损失,降低锂离子电池能量密度。为解决此问题,选用氧化锂作为牺牲锂盐以补偿锂离子电池的首次不可逆容量损失,提高电池容量和循环性能。通过将催化剂LiMnO_(2)、Li_(2)O和导电炭黑(SP)按一定质量比研磨混合,制备了Li_(2)O基正极补锂材料LiMnO_(2)/Li_(2)O/SP。为研究其补锂性能,选用磷酸铁锂作为正极,石墨作为负极,TCGG-Si作为电解液,组装了2032扣式全电池,通过充放电测试,研究了该正极补锂材料对电池电化学性能的影响。结果表明,当LiMnO_(2)/Li_(2)O/SP的质量分数分别为50%、45%和5%时,在10 mA·g^(-1)的电流密度下充电至4.3 V,LiMnO_(2)/Li_(2)O/SP复合材料的首次充电比容量可达526.5 mAh·g^(-1),首次库伦效率为14.63%,其在首次充电过程中分解释放活性锂的过程是不可逆的,并在第4次后完全丧失容量,说明Li_(2)O/LiMnO_(2)/SP复合材料可以作为补锂材料添加到正极材料中。将质量分数为3.6%的Li_(2)O/LiMnO_(2)/SP复合材料加入到磷酸铁锂半电池中,半电池的首次充电比容量为186.5 mAh·g^(-1),相较LiFePO_(4)比容量(166.8 mAh·g^(-1))提高了19.7 mAh·g^(-1),说明补锂剂已发挥作用,该部分多余的容量可用于形成石墨SEI膜。将Li_(2)O/LiMnO_(2)/SP添加到磷酸铁锂-石墨全电池体系中作为正极补锂剂,不仅可补偿石墨负极的首次不可逆容量损失,还可提高全电池的循环性能。全电池的首次可逆容量为158.2 mAh·g^(-1),循环100次的可逆比容量为108.0 mAh·g^(-1);相较于未添加情况,全电池首次充电比容量增加了12.9 mAh·g^(-1),可逆比容量提高了11.6 mAh·g^(-1),经100次循环后容量保持率提升了13.90%。

镍钴锰酸锂三元正极材料的改性研究进展

锂离子电池的容量、循环寿命和安全性等性能很大程度上依赖于正极材料。镍钴锰酸锂(NCM)三元正极材料具有能量密度高、成本低、相对安全等优点而备受关注。但阳离子混排、界面副反应、不可逆相变等问题的存在严重影响了电池的循环和倍率等性能。综述了NCM正极材料的结构特点、问题成因,并从掺杂、表面包覆、单晶和浓度梯度结构等角度探讨了其改性研究情况,对其未来研究方向进行了展望。

Effect and mechanism of manganate preoxidation for organics removal

The performance and mechanism of manganate preoxidation process for organics removal were investigated in the present paper.The results showed that manganate was a potentially powerful oxidizing agent and could make the natural organic matter(NOM)concentration of sample solution increase.The process of manganate in combination with ferrous sulphate(FeMnO)was effective for organics removal and with the highest removal rate of 89%when the FeMnO dose was 0.18 mmol/L.The fluorescence analysis showed that the fluorescence intensity values related to hydrophobic acids and model humic acid polymers were the highest and the relative position of the main peak fluorescence intensity was shifted towards lower emission wavelengths,which indicated the reduction in the degree of aromaticity of residual organic matter fraction.

低共熔溶剂浸出废旧锰酸锂电池正极材料锂和锰的研究

低共熔溶剂做为绿色溶剂在废旧锂电池有价组分回收领域研究受到人们日益关注,以废旧锰酸锂电池正极粉为对象,研究了盐酸胍和乳酸低共熔溶剂对锂和锰的浸出性能,考察了浸出温度、浸出液固比和浸出时间等条件对锂和锰的浸出率影响,研究结果表明:采用盐酸胍和乳酸摩尔比1∶2制备的低共熔溶剂,适宜的溶解条件为浸出液固体积质量比为10 mL/g,溶解温度为70℃,浸出时间为2 h,在此条件下锰酸锂正极粉中锂和锰的浸出率分别达到99.27%和99.20%。

不同动力电池新能源货运配送车辆节能减排绩效评价研究

为研究新能源货运车辆装配不同动力电池对节能减排的影响,选取某款新能源货运配送车辆为研究对象,利用GaBi软件建立了3种常用动力电池的整车生命周期评价模型,从原材料获取、生产制造、装配、运行使用、报废回收5个阶段进行节能减排差异分析,并对全球变暖潜值(Global Warming Potential,GWP)等环境影响类型进行归一化处理和量化计算处理。结果表明,分别装配3种电池整车的化石能源消耗以煤炭为主、环境排放以CO_(2)为主;纯电动汽车的能源消耗、污染物排放集中在运行使用阶段;综合比较,装配了三元锂电池的整车,其全生命周期节能减排效果最佳,装配了锰酸锂电池的整车则表现最差。加大清洁能源的使用力度、减少用于电力生产的化石能源消耗、提高回收率等措施,可以显著减少污染物排放。

钕离子掺杂锰酸锂纳米颗粒的自蔓延燃烧制备与性能研究

采用自蔓延燃烧法制备钕离子掺杂锰酸锂(LiMn_(1.99)Nd_(0.01)O_(4))纳米颗粒,通过XRD、SEM、CV等表征分析了材料的晶体结构、微观形貌和电化学性能.结果表明:钕离子掺杂不影响晶体结构,但可减小LiMn2O4颗粒粒径,进而提高其电化学性能.在0.2C倍率下的放电比容量高达125.6 mAh·g^(-1).在1C倍率下的首次放电容量为118.4 mAh·g^(-1),循环100次后的放电比容量为110.4 mAh·g^(-1),容量保持率为93.2%.

Mg^(2+)掺杂对锰酸锂正极材料电化学性能的影响

尖晶石型LiMn_(2)O_(4)正极材料的电压平台高、原料来源丰富、生产成本低廉,但由于Jahn-Teller效应导致晶格畸变和Mn^(3+)歧化分解导致过渡金属锰的溶解严重影响电池的循环性能。本文探究了不同Mg^(2+)掺杂量对LiMn_(2)O_(4)正极材料电化学性能的影响。采用高温固相法制备了LiMg_((x))Mn_((2-x))O_(4)(x=0,0.01,0.03,0.05)样品,并对其组织结构和电化学性能进行分析。结果表明,所有样品均为立方尖晶石结构,呈截断八面体形貌。电化学性能测试表明,当x=0.03时,LiMg_(0.03)Mn_(1.97)O_(4)样品在0.2 C下具有较高的放电比容量和最高的首次库伦效率(98.44%),循环稳定性最佳;在0.5 C下循环100圈后仍具有119.3 mAh/g的放电比容量,容量保持率高达92.62%。

钠离子电池锰酸钠正极材料研究进展与发展趋势

近年来,钠离子电池凭借钠资源储量丰富、分布广泛、价格低廉、绿色可持续发展、安全稳定、集成效率高、快速充电性能优异、低温性能好等一系列优势被认为是锂离子电池当前最好且最有发展前景的互补品,也是未来发展大规模电化学储能最具前景的系统之一。然而阻碍钠离子电池发展的因素是正极材料体系结构易发生相变、放电比容量不够高、循环性能不够好等问题。目前,钠离子电池正极材料的研究中过渡金属氧化物材料表现出更多样的结构种类、更优的结构稳定性、更高的比容量、良好的充放电循环性能和其他优异的电化学性能。本文针对锰酸钠正极材料微观以及宏观结构的研究进展进行归纳总结,着重对不同钠含量的锰酸钠材料通过三种不同位点(钠位、锰位和氧位)掺杂以及包覆的手段进行系统深入的研究,详细展示并论述了不同元素不同位点掺杂以及不同包覆手段所带来的增益效果。在未来的发展过程中,应加强对微观宏观结构的进一步提升,拓展多元素多位点掺杂种类、掺杂比例、搭配类型和包覆材料种类等,提升包覆技术,并不断加强钠离子电池电解液、负极材料等配件的创新与发展。

基于水溶性煤沥青的MnO@C复合材料的制备及储锂性能研究

目的制备出具有高容量、良好的倍率性能和循环稳定性的MnO@C复合电极材料。方法使用水溶性煤沥青及KMnO4为原料,通过水热法制备出Mn3O4@C前驱体。然后经过高温碳热还原制备MnO@C复合电极材料。通过SEM、XPS、XRD和Raman等分析技术对MnO@C复合材料的形貌、表面、结构等进行表征,并使用循环伏安、恒流充放电和电化学阻抗等电化学分析技术对其电化学性能进行了评价。结果TEM和SEM结果表明,制备的水溶性煤沥青表面丰富的含氧官能团与MnSO4溶液中的Mn2+之间有较强的相互作用,提供成核位点,进而促进了后续MnO@C材料中纳米颗粒的形成和均匀生长。这些纳米粒子的形成又起到了提升MnO@C电化学性能的作用。XRD、Raman和XPS结果表明,Mn3O4@C前驱体经过高温碳热还原反应生成MnO@C后,在MnO表面和包覆的碳材料之间生成了大量的Mn—O—C键。电化学结果表明,MnO@C电极在0.1 A/g电流密度下循环100圈后具有606.47 mAh/g较高的储锂容量,即使是在0.5 A/g大电流密度下循环400圈后仍具有293.83 m Ah/g的储锂容量。同时,电化学测试也表明,MnO@C复合材料具有非常好的倍率性能。结论使用鞍钢产的煤沥青根据混酸法制备了水溶性煤沥青。通过使用水溶性煤沥青和KMnO4成功地制备了Mn3O4@C前驱体。以Mn3O4@C前驱为原料,通过高温碳热还原法制备了MnO@C复合材料。在MnO表面包覆碳层不仅提供活性位点而且起到限制在充放电过程中MnO体积膨胀的作用。特别值得注意的是,Mn—O—C键构筑了MnO和碳层之间的快速导电通道,提升了电极反应动力学。