钛系锂离子筛的制备及其吸附性能研究

以无定型水合二氧化钛和氢氧化锂分别作为钛源和锂源,通过高温固相法合成钛系锂离子筛（HTO）并进行了扫描电镜（SEM）、X射线衍射（XRD）、接触角测试等表征。研究了HTO在高镁锂比[n（Mg）/n（Li）]盐湖卤水中随时间变化对锂吸附容量的影响。结果表明,HTO在高镁锂比盐湖卤水中26 h吸附容量达到24.8 mg/g。HTO具有优异的选择性,分离系数（α^Li _Mg）达到4 813.0。经过20次吸附循环试验,HTO的锂吸附容量仅下降4.8%,且每次钛的溶损率都在0.08%以下。结果表明,HTO具有较好的循环吸附性能和稳定性。该HTO具有从高镁锂比盐湖卤水提取锂的能力,具有很广阔的市场前景。     

Spray-drying assisted synthesis of a Li4Ti5O12/C composite for high rate performance lithium ion batteries

Spinel crystalline lithium titanium oxide (Li₄Ti₅O₁₂ or LTO) has gained attention as a possible alternative material to graphite for use as anodes in lithium-ion rechargeable batteries due to its low volume expansion and dendrite-free long-term stability. However, the rate capability of LTO is limited by its low electronic conductivity, which results in a large polarization resistance between electrodes. In this study, we demonstrate a spray-drying-assisted carbon coating approach to synthesize LTO/C composites for enhanced lithium-insertion capacity and facilitated charge-discharge reaction kinetics. The thin carbon layer of LTO/C composite contributes to suppressing particle growth by forming passivating carbon layers. In addition to the decrease in particle size for short lithium-diffusion pathways, the highly conductive carbon layers reduce the interfacial resistance between the electrode and electrolyte by enhanced electrical conductivity. The electrochemical performances of the spray-drying-prepared LTO/C composite such as the specific capacity, cycle and rate capabilities, and impedance are compared with pristine LTO and carbon-coated LTO synthesized without spray-drying. The LTO/C prepared from glucose exhibits a 11.15% enhancement in rate characteristics of pristine LTO at 0.5 C after 100 cycles. These results indicate that the carbon coating layer promotes charge transfer and ion diffusion as well as provides a buffering effect for improved rate and cyclic capabilities.     

硝酸锂改性钛系离子筛的制备及其吸附性能

钛系锂离子筛具有较高的锂吸附容量和稳定性,对其制备工艺及性能进行改进研究具有重要意义。使用硝酸锂和碳酸锂混合物作为锂源,与二氧化钛在500℃下进行固相反应,生成层状钛酸锂;使用0.2 mol·L ^-1盐酸对其酸洗24 h,得到了锂离子筛吸附剂;采用X射线衍射、扫描电镜、粒度分析、N ₂吸附-脱附方法等,对其性能进行了表征;通过锂离子的吸附实验,确定了吸附和再生性能;探究了该新型吸附剂的锂离子吸附机理。结果表明：吸附过程是单分子层化学吸附;经过改性,离子筛颗粒更加细小,孔体积和比表面积更大,结构完整;在70 mg·L ^-1的Li ⁺溶液中,吸附量为25.01 mg·g ^-1,准二级吸附速率常数为0.2762 g·(mg·h) ^-1,吸附速率较之未改性提高了54.56%;该离子筛对浓度为11.6 mg·L ^-1的Li ⁺溶液,其锂去除率可以达到99.77%。     

锰氧化物锂离子筛的掺杂改性及吸附性能研究

以二氧化锰和氢氧化锂为原料,采用高温固相法合成了锂锰氧化物前驱体,再经离子交换技术制备了锰氧化物锂离子筛并用于溶液中Li ⁺的吸附。考察了Al ³⁺和La ³⁺掺杂对锂离子筛结构、形貌和吸锂性能的影响。用粉末X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）对制备产物进行了表征。结果表明,产物为尖晶石型锰氧化物锂离子筛,呈片状形貌,分散性较均匀。Al ³⁺和La ³⁺掺杂后产物仍然保持尖晶石结构,形貌有所变化,分别呈现出不规则的立方体和纳米颗粒。吸附结果表明,掺杂后锰氧化物锂离子筛的吸附容量有所提高。     

Preparation and adsorption performance of multi-morphology H1.6Mn1.6O4 for lithium extraction

In this paper, a lithium-ion sieve(LIS) with different morphologies, such as rod-like(LIS-R), spherical(LIS-S),flower-like(LIS-F), and three-dimensional macroporous-mesoporous(LIS-3D), was prepared by hydrothermal synthesis, solid reaction, and hard-template synthesis. The results showed that the LIS with different morphologies presented great differences in specific surface area, pore volume, adsorption selectivity, and structure stability. LIS-3D with highest specific surface area and pore volume displayed the maximum adsorption capacity and adsorption rate, but the stability of LIS-3D was poor because of the manganese dissolution. By comparison, LIS-S has the best structural stability while maintaining a satisfactory adsorption capacity(35.02 mg·g~(-1)) and adsorption rate. The LIS-S remained about 90% of the original adsorption capacity after five cycles of adsorption–desorption process. In addition, in the simulated brine system(the magnesium to lithium ratio of 400), the LIS-S exhibited the highest selectivity(α_(Mg)~(Li)) of 425.14. In sum, the LIS-S with good morphology is a potential adsorbent for lithium extraction from brine.     

吸附法提取煤矸石中锂的工艺

平朔煤矸石中锂元素含量较高,寻找适合的提取方法具有重要的研究价值和应用前景。本文利用盐酸酸浸活化的煤矸石使锂溶到溶液中,采用自制的锰系离子筛对溶液中的锂进行吸附,实现锂的回收。主要考察了活化配比、活化温度、酸浸温度、酸浸体积、酸浸浓度等因素对煤矸石中锂浸出率的影响,通过单一控制变量法确定了最佳焙烧和浸出工艺条件,使锂的浸出率达到79%以上;研究了不同温度和时间对合成离子筛的影响,利用X射线衍射仪、扫描电镜、电感耦合等离子体发射光谱仪对离子筛晶型以及吸附性能进行表征,结果显示800℃下煅烧15h可以合成晶型完整的LiMn₂O₄尖晶石,且在溶液pH=14固液比1∶500时H型离子筛吸附容量达到了24mg/g;ICP数据处理结果表明H型离子筛对活化的煤矸石酸浸液中的锂吸附率达到了99%以上。     

Effects of TiO2 starting materials on the synthesis of Li2ZnTi3O8 for lithium ion battery anode

Lithium zinc titanate (Li₂ZnTi₃O₈) anode materials have been successfully synthesized using rutile-TiO₂ with different particle sizes as titanium sources via a molten-salt method. Various physical and electrochemical methods are applied to characterize the effects of TiO₂ particle sizes on the structures and physicochemical properties of the Li₂ZnTi₃O₈ materials. When the particle size of TiO₂ is too small (10 nm), it is difficult to homogeneously mix TiO₂ with the other raw materials. Thus, the final product Li₂ZnTi₃O₈ has poor crystallinity, large particle size, small specific surface area, pore volume and average pore diameter, which are disadvantageous to its electrochemical performance. Using TiO₂ with the proper particle size of 100 nm as the titanium source, the Li₂ZnTi₃O₈ (R-100-LZTO) with excellent electrochemical performance can be obtained. At 1 A g⁻¹, 175.8 and 163.6 mA h g⁻¹ are delivered at the 1st and the 200th cycles, respectively. The largest capacities of 163, 133.3 and 122.5 mA h g⁻¹ are delivered at 2.5, 5 and 6 A g⁻¹, respectively. The good high-rate performance of the R-100-LZTO originates from the good crystallinity, small particle size, large specific surface area and average pore diameter, low charge-transfer resistance and high Li⁺ diffusion coefficient.     

High performance PPO/Ti3+/TiO2NT membrane/electrode for lithium ion battery

In order to improve the electrical conductivity and electrochemical performances of lithium ion battery, the electrodeposition of poly(phenylene oxide) (PPO) on Ti³⁺-doped TiO₂ nanotube arrays (Ti³⁺/TiO₂NT) was designed and achieved via self-doping of Ti³⁺ and the following electropolymerization of phenol monomers. The as-synthesized PPO/Ti³⁺/TiO₂NT membrane/electrode was investigated in terms of SEM, EDX, XPS, galvanostatic charge/discharge, cycle voltammetry (CV) and AC impedance. As expected, PPO film indeed grew onto the surface of Ti³⁺/TiO₂NT electrode via one-step electrodeposition; furthermore, PPO/Ti³⁺/TiO₂NT membrane/electrode delivered satisfactory rate performances and cycle stability, mainly attributed to the joint contributions from higher electrical conductivity of Ti³⁺/TiO₂NT electrode and the synergy effects between Ti³⁺/TiO₂NT electrode and loose PPO film.     

结构化5A分子筛吸附床结构及工艺参数对N2/H2吸附性能的影响

利用吸附等温线获得动力学参数,建立了CFD模型,模拟了氢气/氮气在结构化5A分子筛吸附床中的吸附过程,研究了吸附剂层片间距、吸附剂厚度等结构参数和吸附压力、进气流量等工艺参数对混合气吸附效果的影响。结果表明：减小层片间距和吸附剂厚度可显著提高传质系数和床层利用率。增大吸附压力可提高床层利用率,但会减小传质系数。进气流量对传质系数的影响不明显,但当流量较大时,吸附容量和床层利用率均呈减小趋势。结构化5A分子筛吸附剂吸附性能良好。     

Amorphous TiO2-Derived Large-Capacity Lithium Ion Sieve for Lithium Recovery

The lithium titanium oxide ion sieve with good structural stability and high adsorption capacity is generally considered to be a promising adsorbent for lithium recovery. Herein, the lithium ion sieve precursor Li₂TiO₃ was prepared based on amorphous TiO₂, and then Li⁺ was acid-eluted to obtain the lithium adsorbent H₂TiO₃, denoted as HTO-Am. The structure and adsorption properties of HTO-Am were investigated, and the results demonstrated that the HTO-Am prepared at the optimum temperature had excellent adsorption properties for Li⁺. The adsorption process follows pseudo-second-order kinetic and Langmuir isotherm equations, indicating that lithium is adsorbed chemically and monolayer on HTO-Am. HTO-Am ion sieves were prepared successfully for the first time and exhibited high selectivity, favorable adsorption rate, and cycle performance for Li⁺.     

废旧锂离子电池制备锂离子筛及其应用研究进展

锂离子电池报废量爆发式增长,预计到2023年,废旧锂离子电池回收利用将是一个超过300亿元产值的新兴市场,其中,锂资源占可回收金属价值的一半。为探索锂资源高效回收技术,基于现阶段研究热点,讨论了以废旧锰酸锂电池正极材料、废旧三元锂电池正极材料、废旧锰系锂离子电池负极材料为原料制备锂离子筛的方法;探讨了废旧锂离子电池中各类杂质成分对锂离子筛性能的影响;阐述了锰系锂离子筛技术在废旧锂离子电池的锂回收、盐湖卤水提锂和化工制药废水提锂等领域的应用。通过分析得出,锂离子筛的应用能够增加锂盐回收率与回收纯度,降低技术成本,应用前景广阔。     

锂离子筛吸附剂及成型的研究进展

对提锂离子筛进行了分类。依据提锂离子筛的吸附机理,综述了锰系、钛系和掺杂系提锂离子筛的制备方法、掺杂改性及其造粒成型的研究进展。阐明了离子筛目前存在的主要问题和其难以工业化的瓶颈,对其今后的研发及应用进行了展望。     

纳米纤维锂离子筛吸附剂的制备及表征

通过静电纺丝制备了锂离子筛负载纳米纤维。研究了聚丙烯腈（PAN）和锂锰氧化物（Li1.6Mn1.6O4）配比对纳米纤维锂离子筛吸附剂提锂性能的影响。采用扫描电镜（SEM）和BET氮气吸附法对纳米纤维锂离子筛吸附剂的形貌和比表面积进行了表征。实验结果表明,在聚丙烯腈质量分数为7%和Li1.6Mn1.6O4质量分数为10%条件下,制得的纳米纤维锂离子筛吸附剂比表面积较大、提锂性能较好,其在质量浓度为10 mg/L的氯化锂溶液中对锂离子的吸附量可达13.6 mg/g。纳米纤维锂离子筛吸附剂克服了粉末状锂离子筛的不足,对实现海水提锂具有重要的参考价值。     

PVC-MnO2的制备及其对锂离子的吸附行为

MnCO3和Li2CO3经高温煅烧合成Li4Mn5O12,再与聚氯乙烯(PVC)和N,N-二甲基甲酰胺溶液混合,干燥、酸洗后制得粒径3?4 mm的多孔球形PVC?MnO2锂离子筛,用其吸附Li离子. 结果表明,PVC?MnO2吸附Li离子的反应符合Langmuir方程和拟二级动力学方程,吸附焓变为0.358 kJ/mol,吸附反应为吸热反应,Li离子最高吸附量可达23.4 mg/g.     

Nanowires embedded porous TiO2@C nanocomposite anodes for enhanced stable lithium and sodium ion battery performance

A porous carbon nanocomposite with embedded TiO₂ nanowires (NWs) was synthesized using a two-step synthetic method in which carbon matrix was obtained by carbonizing a vacuum dried gel. This unique structure in which TiO₂ nanowires uniformly distributed in and tightly bonded to the carbon matrix shortened the electron transport path and reduced the transmission resistance. Nanoporous structure ensured continuous transfer of Li⁺/Na⁺ and supplied a large specific surface area of 280.82 m² g⁻¹ to provide more active sites. Different from other existing works on TiO₂@C anode materials with TiO₂ loading higher than 60 wt%, the obtained very small amount of TiO₂ (~12 wt%) improved the electrochemical and long-cycle performance of carbon substrate with TiO₂ NWs embedded significantly, due to uniformly distributed TiO₂ NWs throughout the carbon matrix. These TiO₂@C composite anodes could deliver a specific capacity of 286 mA h g⁻¹ at 0.3 C, 197 mA h g⁻¹ at 0.15 C for lithium and sodium ion batteries, respectively. It maintained remarkably stable reversible capacities of 128 and 125 mA h g⁻¹ for lithium and sodium ion batteries at 3 C during 2500 cycles, respectively. Smaller fluctuations and smoother curves demonstrated that sodium ion storage was more stable than lithium ion storage for the TiO₂@C composite anode. In addition, the capacitive contributions of TiO₂@C in both systems are quantified by kinetics analysis.     

High performance binder-free quaternary composite CuO/Cu/TiO2NT/Ti anode for lithium ion battery

High performance binder-free quaternary composite CuO/Cu/TiO₂ nanotube/Ti (CuO/Cu/TiO₂NT/Ti) electrode for lithium ion battery was designed and synthesized via anodization, electrodeposition and thermal oxidation at 450 °C in the air. The as-prepared binder-free quaternary composite CuO/Cu/TiO₂NT/Ti electrode was studied in terms of XRD, XPS, SEM, EDX, galvanostatic charge/discharge, cycle stability, cyclic voltammetry (CV) and AC impedance. As expected, the binder-free quaternary composite CuO/Cu/TiO₂NT/Ti electrode displayed much higher discharge capacity, cycle stability, Li⁺ diffusion coefficient than bare TiO₂NT/Ti electrode. High Li-storage activity of CuO, high conductivity of Cu and the synergy effect among various components should be responsible for improved electrochemical performances. Additionally, binder-free combination of the various components may also contribute into the modifications due to the exclusion of negative effect of polymer binder.     

Facile synthesis of hierarchical polycystic iron-nitride/phosphide hybrids microsphere constructed by CNTs for stable and enhanced lithium storage

Diverse Fe-based nitrides and phosphides have drawn considerable attention owing to their abundant source, high theoretical capacities, and environment benignity. However, it still remains a crucial challenge to develop a facile preparation approach of robust Fe-based anode materials for the next-generation durable lithium-ion batteries. Herein, we constructed two type polycystic microsphere anode materials (Fe₂N@C/CNTs and FeP@C/CNTs) through a scalable industrial spray-drying technology combined with following chemical nitridation/phosphorization conversion strategy. Both the resultant Fe₂N@C/CNTs and FeP@C/CNTs materials exhibit unique hierarchical polycystic microsphere structure and improved conductive network caused by the incorporation of amorphous carbon and dense CNTs coating layers. The unique structure merits endow these capabilities of facilitating electrons/ions transport and accommodating notorious volume change during charge-discharge cycling. Consequently, the Fe₂N@C/CNTs and FeP@C/CNTs anode materials deliver enhanced rate capability (216 and 232?mA?h?g^?1, respectively, at a high current density of 5?A?g^?1) and durable cycling stability with reversible capacities of 489 and 571?mA?h?g^?1 at 0.5?A?g^?1 after 500 cycles, respectively. In addition, this work also provides a transplantable preparation strategy for other conversion-type anode materials with poor electrical conductivity and large volume effect.     

4A分子筛改性催化剂制备及其吸附氨氮的性能

分别采用过渡金属(Fe,Zn,Cr,Cu)、盐酸、氢氧化钠以及十二烷基硫酸钠(SDS)对4A分子筛改性,并测其吸附污水中氨氮性能。结果表明,Fe和SDS协同改性的4A分子筛去除氨氮性能最佳,在25℃时,单分子层饱和吸附量为3.20 mg/g,其吸附动力学符合准二级反应动力学方程。     

Stellerite-seeded facile synthesis of zeolite X with excellent aqueous Cd2+ and Ni2+ adsorption performance

Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed, and its adsorption performance for Cd²⁺ and Ni²⁺ ions was experimentally and comprehensively investigated. The effects of pH, zeolite X dosage, contact time, and temperature on adsorption performance for Cd²⁺ and Ni²⁺ ions over were studied. The adsorption process was endothermic and spontaneous, and followed the pseudo-second-order kinetic and the Langmuir isotherm models. The maximum adsorption capacitiesfor Cd²⁺ and Ni²⁺ ions at 298 K were 173.553 and 75.897 mg·g^-1, respectively. Ion exchange and precipitation were the principal mechanisms for the removal of Cd²⁺ ions from aqueous solutions by zeolite X, followed by electrostatic adsorption. Ion exchange was the principal mechanisms for the removal of Ni²⁺ ions from aqueous solutions by zeolite X, followed by electrostatic adsorption and precipitation. The zeolite X converted from stellerite zeolite has a low n(Si/Al), abundant hydroxyl groups, and high crystallinity and purity, imparting a good adsorption performance for Cd²⁺ and Ni²⁺ ions. This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd²⁺ and Ni²⁺ ions from aqueous solutions.     

LiMn2O4 spinel direct synthesis and lithium ion selective adsorption

The cubic phase LiMn₂O₄ spinel is synthesized via a directly soft chemistry method via hydrothermal reaction of Mn(NO₃)₂, LiOH and H₂O₂ at 383 K for 5–10 h, more favorable to control the nanocrystalline structure with well-defined pore-size distribution and high surface area than traditional solid-phase reaction at high temperature. Further, the 1D MnO₂ nanorod ion-sieves with lithium ion selective adsorption property is prepared by the acid treatment process to completely extract lithium ions from the LiMn₂O₄ lattice. The effects of hydrothermal conditions on the nanostructure, chemical stability and ion-exchange property of the LiMn₂O₄ spinel and MnO₂ ion-sieve are examined via powder X-ray diffraction (XRD), N₂ adsorption–desorption at 77 K, high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED) and lithium ion selective adsorption measurements. The results show that the 1D MnO₂ nanorods might be utilized in lithium extraction from aqueous environment including brine, seawater and waste water.