Impact of Urbanization on Low-Temperature Precipitation in Beijing during 1960–2008

Daily precipitation and temperature records at 13 stations for the period 1960-2008 were analyzed to identify climatic change and possible effects of urbanization on low-temperature precipitation [LTP, precipitation of ≥ 0.1 mm d^-1 occurring under a daily minimum temperature （Tmin） of ≤ 0℃] in the greater Beijing region （B JR）, where a rapid process of urbaniza tion has taken place over the last few decades. The paper provides a climatological overview of LTP in B JR. LTP contributes 61.7% to the total amount of precipitation in B JR in the cold season （November-March）. There is a slight increasing trend [1.22 mm （10 yr）^-1] in the amount of total precipitation for the cold season during 1960-2008. In contrast, the amount of LTP decreases by 0.6 mm （10 yr）^-1. The warming rate of Train in B JR is 0.66℃ （10 yr）^-1. Correspondingly, the frequency of LTP decreases with increasing Tmin by -0.67 times per ℃. The seasonal frequency and amount of LTP in southeast B JR （mostly urban sites） are 17%-20% less than those in the northwestern （rural and montane sites）. The intensity of LTP for the urban sites and northeastern B JR exhibited significant enhancing trends [0.18 and 0.15 mm d^- 1 （10 yr）^- 1, respectively]. The frequency of slight LTP （〈0.2 mm d^-1） significantly decreased throughout B JR [by about -15.74% （10 yr）^-1 in the urban area and northeast B JR], while the contribution of the two heaviest LTP events to total LTP amount significantly increased by 3.2% （10 yr） ^-1.

Mechanism analysis of ions interaction in MgCl_2/LiCl solution and effect of lithium on ammonia precipitation products

Producing magnesium hydroxide is the basic way to utilize magnesium resources of natural brines. However, the effect of lithium on properties of product is always neglected. The interaction between ions in magnesium chloride solution containing lithium was illustrated based on the experimental results, and the effect of lithium on the crystallization of magnesium was clarified. The results of X-ray diffraction（XRD）, scanning election microscope（SEM）, Fourier transform infrared spectroscopy（FTIR）, thermogravimetry analysis（TGA） and laser particle size analysis indicate that the effect of lithium is not obvious on the crystal phase and morphology of the products. But the XRD relative intensity of（001） surface of magnesium hydroxide declines, the specific surface area reduces apparently and the additive mass of lithium affects the heat loss rates of precipitations obviously. Quantum chemical calculations on the interactional systems of Mg（H2O）2＋6 and Li（H2O）＋4 were performed using B3LYP/6-311 G basis set. The results show that when the distance of Mg2＋ and Li＋ is 7-10 , the interaction energy is high and the trend of solvation is strong, which would make hydroxide ions easier to combine with hydrogen ions in ammonia precipitation process. And the absolute value of solvation free energy reduces significantly in MgCl2 solution（1 mol/L） containing lithium ion.

Effect of lithium ion on seed precipitation from sodium aluminate solution

Effect of lithium ion in sodium aluminate solution on precipitation rate,lithium content,morphology,and crystallization of alumina trihydrate(ATH) was investigated. Results showed that increasing lithium ion concentration in solution improved the precipitation rate and lithium content in ATH,whereas reduced the mass fraction of lithium precipitation from solution. Lithium ion in solution generated the fine ATH, and thereafter significantly increased the total particle number due to the preferential nucleation.Elevating temperature or reducing lithium ion concentration decreased lithium content in ATH and reduced the fine particle amount.Moreover, lithium ion in the solution changed the morphology of ATH by improving the growth of the(110) and(200) planes of gibbsite.A large amount of fine bar-or flake-shaped ATH attached on the coarse particles also benefited the secondary nucleation and led to the poor strength of alumina.All results will further contribute to improving the quality of alumina.

Yttrium-Doped SnO_2 Prepared by Co-Precipitation Method for Lithium-Ion Battery Anodes

SnO2 doped with Y were prepared by co-precipitation method and tested in lithium-ion cells. The structure and morphology of the materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns presented that the all the as-prepared materials had tetragonal rutile structure but a second phase (Y2O3) was observed when Y content reached 4%. TEM micrograph indicated that Y doped SnO2 had a small particle size ranging from 20 to 25 nm. The electrochemical properties for an anode active material in lithium-ion batteries were investigated at room temperature, including the observed capacity involved in the first-discharge and the reversible capacity values during subsequent charge-discharge cycles. The as-prepared Y-doped SnO2 exhibited promising electrochemical properties as anodes for lithium-ion batteries.

SnO_(2)/metal organic complex composite derived from low-temperature activated metal organic complex for advanced lithium storage

Sn-based metal organic complexes with coordination bonds,multi-active sites,and high theoretical capacity have attracted much attention as promising anodes for lithium ion batteries.However,the low electrical conductivity and huge volume changes restricted their electrochemical stability and practical utilization.Herein,Snbased anode with superior electrochemical performance,including a high reversible capacity of 1050.1 mAh·g^(-1)at 2 A·g^(-1)and a stable capacity of 1105.5 mAh·g^(-1)after 500 cycles at 1 A·g^(-1),was fabricated via a low-temperature calcination strategy from Sn metal organic complexes.The low-temperature calcination process regulates Sn-O bond and prevents the agglomeration of SnO_(2),generating highly dispersed SnO_(2) decorated metal organic complexes and providing sufficient active sites for ion storage.Ex situ characterizations expound that the undecomposed Sn-based metal organic complexes could be transformed into SnO_(2) during lithiation and delithiation,which enhances the electrical conductivity and induces a strong pseudo-capacitive behavior,accelerating the electrochemical kinetics;the multiple solid electrolyte interface with inflexible LiF and flexible ROCO_(2)Li buffers the volume variation of the electrode,resulting in its high electrochemical stability.This work provides a simple strategy for preparing excellent Sn-based anodes from metal organic complexes and reveals the lithium storage mechanism of the prepared Snbased anode.

Synthesis of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2 cathode material by chloride co-precipitation method

LiNi0.8Co0.1Mn0.1O2 was prepared by a chloride co-precipitation method and characterized by thermogravimetric analysis, X-ray diffractometry with Rietveld refinement,electron scanning microscopy and electrochemical measurements.Effects of lithium ion content and sintering temperature on physical and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 were also investigated. The results show that the sample synthesized at 750℃with 105%lithium content has fine particle sizes around 200 nm and homogenous sizes distribution.The initial discharge capacity for the powder is 184 mA·h/g between 2.7 and 4.3 V at 0.1C and room temperature.

Effects of synthesis conditions on the structural and electrochemical properties of layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 cathode material via oxalate co-precipitation method

The uniform layered LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries was prepared by using （Ni1/3Co1/3Mn1/3）C2O4 as precursor synthesized via oxalate co-precipitation method in air. The effects of calcination temperature and time on the structure and electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 were systemically studied. XRD results revealed that the optimal calcination conditions to prepare the layered LiNi1/3Co1/3Mn1/302 were 950℃ for 15 h. Electrochemical measurement showed that the sample prepared under the such conditions has the highest initial discharge capacity of 160.8 mAh/g and the smallest irreversible capacity loss of 13.5% as well as stable cycling performance at a constant current density of 30 mA/g between 2.5 and 4.3 V versus Li at room temperature.

Synthesis and electrochemical properties of LiNi_(0.8)Al_(0.2-x)Ti_xO_2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi0.8A10.2-xTixO2 （x=0.0-0.20） cathode materials for lithium ion batteries, with Ni（NO3）2, Al（NO3）3, LiOH·H2O, and TiO2 as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi0.8A10.2-xTixO2 were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi0.8A10.2-xTixO2 cathode materials are 0.1,700℃, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO2 layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi0.8A10.2-xTixO2.

Fabrication of Ni-, Co- and NiCo-coated Graphite Microspheres by Heterogeneous Precipitation

The precursors with NiCO3.2Ni（OH）2.2H2O, Co2（OH）2CO3, or both NiCO3.2Ni（OH）2.2H2O and Co2（OH）2CO3 coated graphite microspheres were prepared respectively by the aqueous heterogeneous precipitation using nickel sulfate, cobalt nitrate, sodium carbonate, ammonium bicarbonate and graphite microspheres as the main starting materials. Subsequently, Ni-, Co- and NiCo-coated graphite microspheres were successfully obtained by thermal reduction of the as-prepared precursors at 500 ℃ for 2 h, respectively. These metal-coated graphite microspheres were characterized with a smooth, cohesive surface consisting of fine metallic particles. Optimized precipitation processing parameters of the concentration of graphite microspheres （10 g/L）, the rate of adding reactants （3 mL/min） and pH value （8.0） were determined by a trial and error method. The thermal analysis of the precursors was investigated by TG. Powders of the precursors and the resultant metal-（Ni, Co and NiCo alloy） coated graphite microspheres were characterized by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）.

富锂硫酸盐型盐湖卤水蒸发实验研究进展

随着“双碳”目标的提出,锂在新能源材料领域中的应用受到高度关注,锂的需求呈现爆发式增长。世界锂资源以矿石锂和盐湖锂为主,盐湖锂因其储量大成为未来锂资源开发的重点,因而占比最大的硫酸盐型盐湖成为焦点。因盐湖卤水组成差异较大,叠加硫酸盐型盐湖特殊属性,使得锂在盐田蒸发阶段存在多种结晶形式而造成损失,增加了锂的有效富集难度。总结了前人针对富锂硫酸盐型盐湖的蒸发实验研究结果,结合相图分析总结富锂硫酸盐型盐湖蒸发结晶析盐规律,重点关注锂的浓缩状态及析盐结晶形式,为硫酸盐型盐湖锂资源开发提供参考。

基于降维机理模型的储能电池安全充电在线控制技术

大倍率充电会引起储能电池负极析锂,进一步可能会诱发电池热失控并导致安全事故。而析锂副反应与电池负极电位直接相关,通过模型精确预测负极电位,传输至储能电池管理系统调整充电工况,可以有效抑制负极析锂。因此,文中提出一种基于降维机理简化伪二维(simplified pseudo two-dimensional,SP2D)模型的储能电池安全充电在线控制技术。首先,对伪二维(pseudo two-dimensional,P2D)模型中部分偏微分方程进行降维简化,建立SP2D模型,同时采用不同的方法获取相应的模型参数。其次,使用实验数据的端电压和负极电位对模型进行验证,结果表明模型在不同倍率恒流工况下精度较高。再次,基于SP2D模型结合比例控制器开展电池无析锂安全充电的仿真工作,结果表明,电池经过1895 s充电即达到截止电压4.3 V,且充电过程中负极电位均处于无析锂安全电位区间。最后,对仿真得到的充电策略进行循环和拆解验证,结果表明提出的充电方法能够实现电池无析锂安全充电。

退役锂电池回收废液制备磷酸锂工艺研究

鉴于锂电池报废量大、锂含量高,探讨从退役锂电池回收废液中利用锂资源。根据溶液高钠含锂、碱含量高的特性,采用磷酸钠沉淀法回收锂,系统研究了反应过程中各工艺参数对磷酸锂回收率、纯度及粒度的影响。结果表明反应温度为102℃,磷酸钠1.1倍理论用量,磷酸钠浓度350 g·L^(-1),加料速率5 mL·min-1,搅拌速率500 r·min-1,冷水洗1 L时,磷酸锂收率能达到92.63%,纯度(质量分数,下同)达到98.81%,产品达到彩色荧光粉用磷酸锂行业标准二级要求。该工艺能广泛应用于各种高钠含锂溶液,特别是从锂浓度较低的溶液中回收锂资源,不仅解决了退役锂电池废液排放问题,还为锂资源提取提供了新途径。

退役三元正极材料锂离子电池化学沉淀法回收锂工艺热力学研究

退役三元正极材料锂离子电池锂资源再利用是减少环境污染、解决锂资源短缺的重要方法之一.从退役三元正极材料锂离子电池湿法处理过程中化学沉淀法回收锂流程出发,研究了LiCl、Li_(2)SO_(4)、LiNO_(3)体系不同沉淀回收锂反应的热力学.结果表明:在热力学角度,磷酸钠对于三种体系均有着适宜的沉淀效果;采用氟化物做沉淀剂时,氟盐要优于氢氟酸用于沉淀反应;相比于其他沉淀剂,碳酸钠用于Li_(2)SO_(4)体系沉锂效果最不好.

基于参比电极的析锂电池安全充电控制

电池系统是支撑下一代新型电网的关键,然而不合理的充放电策略会使电池发生析锂副反应,导致电池充放电性能大幅减弱。因此,文中针对三元锂离子电池,基于参比电极揭示了析锂后电池的充电性能变化情况,并对其安全充电电流进行控制。首先,设计不同温度下的充放电循环实验,得到低温循环与高温循环后的电池;其次,通过植入参比电极标定安全充电曲线对比电池的负极电位,发现高温循环后的电池发生了析锂,且平均充电电流相比新电池降低了61.7%;最后,对析锂后的电池建立安全充电荷电状态-温度-电流等高线图,对比新电池等高线图后发现,200 A以上的充电电流区域减少了69.84%。文中提供了一个析锂后电池充电性能衰减的量化指标,需要在实际的锂离子电池全寿命周期管理中予以考虑。

固相法合成钴掺杂锰系锂离子筛的吸附性能

随着5G/6G通信、新能源汽车、锂电池产业的快速发展,近年来对锂化合物(尤其是Li_(2)CO_(3))的需求急剧增加,许多国家将锂视为战略矿产资源.目前从锂沉淀母液中提取锂受到了极大的关注.锰系离子筛(LMO)是一种具有广泛应用前景的吸附剂,可实现复杂溶液中锂的高效回收.但LMO在酸洗解吸过程中存在锰溶损严重的难题,会降低吸附性能和循环性能.针对上述问题,本研究提出引入Co^(3+)掺杂降低LMO锰溶解损失的策略,制备了钴掺杂锰系离子筛(LCMO).采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等方法对不同煅烧温度和焙烧时间下制备的LCMO进行表征分析.表征结果表明,Co掺杂对LMO的尖晶石结构没有影响,并且Co最佳掺杂摩尔分数为5%,此时离子筛前驱体中Mn^(3+)的原子分数从未掺杂的9.67%降低到3.63%,对应的锂吸附容量从39.299 mg·g^(-1)显著增加到41.708 mg·g^(-1),锰溶损也从1.288%显著降低至0.837%,大大地增加了锰系离子筛的实际应用可能性.制备的摩尔分数为5%Co掺杂的离子筛(LCMO-5%)具有良好的循环性能,Li^(+)的吸附能力在5次循环后仍然保持在81%以上.在模拟的锂沉淀母液中,Li/Na和Li/K之间的分离系数分别为74.655和64.547,这证明了LCMO-5%能有效地从高Na^(+)、K^(+)溶液中吸附分离Li^(+).因此,LCMO-5%离子筛具有从锂沉淀母液中提取Li+的应用前景.

锂离子电池石墨负极失效及其先进表征方法

在便携式设备和电动汽车发展日益受到关注的背景下,锂离子电池凭借其能量密度高、循环寿命长、自放电小等优点成为了大规模应用的商业电池。然而,锂离子电池在使用的过程中存在析锂、短路、热故障以及产气等多种失效形式,造成了锂离子电池容量衰减、电池膨胀、热失控等。因此,揭示电池失效原因对高安全长寿命锂离子电池进一步发展有着巨大的推进作用。本文针对锂离子电池中应用较为普遍的石墨负极,阐述了石墨负极在析锂、高低温、过充等条件下的失效机制,并重点介绍了对于不同失效机制下的先进表征方法,其通过石墨的结构、脱嵌锂时的相变、石墨表面的形貌、负极所释放的热量和反应所产生的气体等多种途径进行分析,总结出四种失效原因主要影响了石墨层间距、石墨脱嵌锂时的相变、活性锂的损耗,另外还会有界面膜生成以及一系列副反应等失效机制。最后,本文归纳了针对各种失效原因的表征方法并进行了分类,同时展望了对于电池失效分析的规范化和标准化,对未来的电池失效分析研究有一定的推动作用。

共沉淀—喷雾干燥法制备类球形磷酸铁前驱体及其性能研究

研究了以七水合硫酸亚铁(FeSO_(4)·7H_(2)O)和磷酸二氢铵(NH_(4)H_(2)PO_(4))为原料,采用共沉淀—喷雾干燥法制备类球形电池级磷酸铁,考察了表面活性剂十六烷基三甲基溴化铵(CTAB)加入量、反应时间、溶液pH对磷酸铁物相和粒径的影响,并利用激光粒度仪、X射线粉末衍射仪、热重分析仪、场发射扫描电镜等对产物进行了表征。结果表明:在Fe/P物质的量比为1/1.01、CTAB加入量0.04g、反应时间1h、溶液pH=3.0条件下,磷酸铁粒径分布范围最小,为300~500nm,且呈较为规则的类球形;以类球形磷酸铁作为前驱体铁源,经球磨混合烧结制备的磷酸铁锂,在0.1C下放电比容量为150.14mAh/g,1C循环200次后保持率为98.9%,性能良好。

盐湖锂资源现状及提锂技术研究进展

锂广泛应用于新能源汽车、电子产品、储能等诸多领域,在能源结构转型中是一种关键战略资源.从盐湖卤水中提取和分离锂,具备资源储量大、成本低等特点,引起了世界范围内的广泛关注.中国盐湖资源丰富,主要分布于青海和西藏等地,但存在锂浓度较低、镁锂比高和分离难度较大的问题.同时,不同地区盐湖成分差异大,技术通用性差,阻碍了我国盐湖提锂的发展.本文从盐湖锂资源的分布、禀赋特征和提取方法以及发展方向等方面,综述了盐湖卤水提锂的主要研究进展.重点介绍了沉淀法、溶剂萃取、吸附法、膜分离和电化学提锂的基本原理、操作和发展趋势,分析了不同提取方法的优缺点、分离效果和适用条件.传统的沉淀法和萃取法均存在药剂用量大,环境污染严重的问题;吸附法用水量大,吸附剂易溶损,导致其生产应用受限.而新兴的膜分离和电化学方法具有分离效果好、药剂添加需求少、产生废物少、适用性广等优点,在分离Mg/Li或Na/Li方面表现出优异的性能,展现出较好的工业应用潜力.最后对盐湖提锂技术未来的发展方向和研究重点进行了展望.

前驱体预处理对富锂锰基氧化物电化学的影响

实验通过小规模共沉淀和固相反应成功合成了无钴富锂锰基前驱体Ni_(0.3)Mn_(0.7)(OH)_(2),将前驱体不进行和进行机械粉碎,分别得到2种不同粒径的Ni_(0.3)Mn_(0.7)(OH)_(2)(D_(50)=1.626μm和0.710μm)前驱体。不同粒径大小的前驱体与LiOH以1∶1.55的摩尔比混合,经过高温烧结,合成2种颗粒大小的富锂锰基正极材料Li_(1.2)Ni_(0.24)Mn_(0.56)O_(2)(D_(50)=1.667μm和1.148μm)。实验结果表明,颗粒尺寸影响其物理化学性质和电化学性能。Li_(1.2)Ni_(0.24)Mn_(0.56)O_(2)(D_(50)=1.148μm)正极材料具有较小颗粒尺寸,显示出优异的电化学性能(在0.5 C下循环100次后,容量为190.7 mAh/g,循环保持率高达91.2%)。研究揭示了一种简易方法改变颗粒大小,并证明了粒径对电化学的重要性。

不同Fe/Ni比值普鲁士蓝类正极材料的制备及储锂性能的研究

采用络合剂辅助共沉淀法合成了不同Fe/Ni比值的铁镍普鲁士蓝化合物(FeNiHCF)粉末,并将制得的FeNiHCF粉末进行了储锂性能探究,利用X射线衍射(XRD)、X光电子能谱(XPS)和扫描电镜(SEM)对于材料的微观结构和形貌进行表征,使用蓝电系统进行恒流充放电测试表征材料的储锂性能。结果表明:不同Fe/Ni比值的掺杂会影响材料的储锂性能及循环稳定性,总体而言,随着镍离子掺杂量的增加,材料的循环稳定性不断上升,但容量有一定的下降。在m(FeCl_(3)·6H_(2)O)∶m(NiCl_(2)·6H_(2)O)=1∶4,1C的电流密度下,首次放电比容量为46.2mAh/g,经500圈循环后放电比容量仍达47.6mAh/g。同时,经过20C的高循环倍率测试后,电流密度回到1C时,比容量仍能恢复到倍率性能测试前,表现出了优异的倍率性能。