A heatproof electrospun PES/PVDF composite membrane as an advanced separator for lithium-ion batteries

In the present paper, the physicochemical properties of a novel composite fibrous membrane, based on a mixture of poly(aryl ether sulfone) (PES) and poly(vinylidene fluoride) (PVDF), as separators for lithium-ion batteries are reported and discussed. Compared with the pure PVDF fibrous membrane, the introduction of PES can decrease the PVDF crystallinity while increasing the proportion of α-phase. Meanwhile, the initial thermal decomposition temperature is enhanced by 24°C. Heat shrinkage tests and thermomechanical analyzers indicate the composite membrane has significantly improved thermal-dimensional stability. The shrinkage rate of the composite membrane after heat-treated at 180°C for 2 hr is only 4.8%, which is far below the Celgard separator (82%) and the pure PVDF fibrous membrane (75%). The composite membrane with excellent wettability demonstrates a high ionic conductivity (1.69 × 10⁻³ S cm⁻¹) at room temperature as well as high electrolyte uptake (595%). The cells assembled with the composite membrane exhibit more stable cycle performance, capacity retention, and C-rate capability than that with polyolefin separator. These results suggest that PES/PVDF composite fibrous membrane is an effective separator for high-performance Lithium-ion batteries.     

A phase inversion based sponge-like polysulfonamide/SiO2 composite separator for high performance lithium-ion batteries

In this work,a sponge-like polysulfonamide(PSA)/SiO_2 composite membrane is unprecedentedly prepared by the phase inversion method,and successfully demonstrated as a novel separator of lithium-ion batteries(LIBs).Compared to the commercial polypropylene(PP) separator,the sponge-like PSA/SiO_2 composite possesses better physical and electrochemical properties,such as higher porosity,ionic conductivity,thermal stability and flame retarding ability.The LiCoO_2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator.Moreover,the sponge-like composite separator can ensure the normal operation of LiCoO_2/Li half-cell at an extremely high temperature of 90 °C,while the commercial PP separator cannot.All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO_2 composite separator is really a promising separator for high performance LIBs.     

锂离子电池正极材料铌掺杂LiNiO2 的制备与电化学性能

为了提高LiNiO₂的电化学性能,用固相反应法制备了铌掺杂LiNiO₂材料,并用X射线衍射（XRD）分析、恒电流滴定技术（GITT）、电化学阻抗谱（EIS）等方法研究铌掺杂量对LiNiO₂的结构和性能的影响。结果表明适量的铌（Nb）掺杂可以提高LiNiO₂层状结构的有序程度,降低Li⁺/Ni²⁺混合程度,降低电荷转移阻抗,提高活性材料中锂离子的扩散系数。其中LiNi_0.99Nb_0.01O₂在0.5C循环100次的容量保持率为91.4%,5C时放电比容量为143 mA·h/g。而未掺杂铌的LiNiO₂在相同条件下的容量保持率和比容量仅为69.2%和127 mA·h/g。结果说明铌掺杂能够有效提高LiNiO₂的电化学性能。     

聚丙烯腈/聚酯无纺布微孔复合锂电隔膜的制备及性能

为了改善锂电隔膜的耐热性、电解液亲和性和机械性能,本文以聚丙烯腈为主要材料,采用相转化法制备了聚酯无纺布支撑的聚丙烯腈微孔复合锂电隔膜,对隔膜的理化性能（孔道结构、机械性能、电解液性能和耐热性）和电池性能（循环性能、倍率性能）进行系统研究。结果表明,复合隔膜具有均匀的微孔结构,平均孔径约为425nm,孔隙率为74%,拉伸强度为30MPa;电解液亲和性良好,吸液率为385%,接触角接近0°,锂离子电导率较市售隔膜显著提高,达到1.65mS/cm;在150℃、0.5h的热处理条件下,复合隔膜的热收缩率为0。鉴于良好的理化特性,该隔膜所装配的钴酸锂/锂金属电池表现出优异的循环容量和倍率容量保持性,如在0.2C倍率下,经历200次循环后电池的放电容量保持率为95.2%,在10C倍率下电池的放电容量为0.5C倍率下的58.3%。因此,相转化法制备的聚丙烯腈基微孔复合隔膜在锂离子电池中显示出较好的应用前景。     

Preparation of 4A zeolite coated polypropylene membrane for lithium-ion batteries separator

This study aims to improve wettability and thermal resistance of lithium-ion batteries separators. For this purpose, a commercial polypropylene (PP) separator was coated by 4A zeolite using poly(vinylidene fluoride) as binder and effects of the separators' zeolite content was investigated. All the coated separators showed lower contact angles, higher electrolyte uptakes, and less thermal shrinkages compared to the neat commercial separator. The coated PPA8 separator (zeolite to binder ratio of 8) showed the lowest wettability (contact angle of 0°) and electrolyte uptake (270%) due to its surface porosity resulting from the zeolite particles interstitial cavities as well as their internal cavities. Also, the PPA8 separator ion conductivity was found as 2.25 mS cm⁻¹ and C-rate and cycling performance of its assembled battery were higher compared to those of the commercial PP separator assembled battery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47841.     

高安全性三甲基硅功能化碳酸丙烯酯电解液的合成及其在锂离子电池中的应用

设计合成了一种新型三甲基硅取代碳酸丙烯酯化合物(TMSPC),并对其化学结构、热性能、离子电导率、电化学窗口和燃烧性能进行了详细的表征。通过与商业电解液(1 mol·L^-1 LiPF₆/EC:DEC=1:1,体积比)互配组成电解液,30%(vol) TMSPC的添加能大大降低电解液的燃烧速率。同时,对LiFeO₄/Li半电池进行测试,在0.2 C倍率条件下,30%(vol) TMSPC的添加也能提高电池的循环性,未添加与添加TMSPC的LiFeO₄/Li 在110个循环后的容量分别为106 mA·h·g^-1和109 mA·h·g^-1,相应的容量保持率为81%和87%。     

氧化铜作锂离子电池负极材料的制备及性能研究

以Cu（NO₃）₂·3H₂O和氢氧化钠为原料,通过水热法制备氧化铜样品。采用X射线衍射法对其进行物相结构的表征。针对pH、反应时间和反应体系浓度等反应条件,对氧化铜样品的物相结构和电化学性能的影响进行了讨论。结果表明,采用该方法制备的氧化铜负极材料在0.1 C（67 mA/g）电流密度下首次充放电容量分别为406.5 mA·h/g和867.4 mA·h/g,在大倍率循环下具有较高的容量保持率。     

Engineering defect-enabled 3D porous MoS2/C architectures for high performance lithium-ion batteries

Designing defect-rich MoS₂/C architectures with three-dimensional (3D) porous frame effectively improve the electrochemical performance of lithium-ion batteries (LIBs) owing to the improved conductivity and decreased diffusion distance of Li⁺ ions for lithium storage. Herein, we report a reliable morphology engineering method combining with tunable defects to synthesize defect-rich MoS₂ nanosheets with a few layers entrapped carbon sheath, forming a 3D porous conductive network architecture. The defect-rich MoS₂ nanosheets with expanded interlayers can provide a shortened ion diffusion path, and realize the 3D Li⁺ diffusion with faster kinetics. A 3D conductive interconnected carbon network is able to improve interparticle conductivity, concurrently maintaining the structural integrity. Benefiting from these intriguing features, the as-prepared MoS₂/C architectures exhibit excellent electrochemical performance: a high reversible capacity of 1163 mAh g⁻¹ at a current density of 0.1 A g⁻¹ after 100 cycles and a high rate capability of 800 mAh g⁻¹ at 5 A g⁻¹. Defect content in MoS₂/C architectures can be obtained by changing H₂ concentration. Compared with the counterparts with few defects, the defect-rich MoS₂/C architectures show improved electrochemical stability with a superior cycle life, illustrating a highly reversible capacity of 751 mAh g⁻¹ at 0.5 A g⁻¹ after 500 cycles.     

锂离子电池高镍三元材料的包覆改性研究进展

锂离子电池高镍三元材料具有循环寿命长、绿色环保、成本低等优点,已成为电动汽车、便携式电子设备等领域的首选正极材料。但是,镍含量的增加容易使材料表面结构不稳定、界面副反应增加,导致材料的循环性能降低。主要从单层包覆和双层包覆两个方面综述了高镍三元材料的改性研究,介绍了不同包覆材料对其电化学性能的影响。双层包覆能更好地改进高镍三元材料的电化学性能,但是在清除氟化氢方面仍需进行研究。     

Sandwich structure of carbon-coated silicon/carbon nanofiber anodes for lithium-ion batteries

For electrospun silicon/carbon nanofiber composites, the surface precipitation of silicon nanoparticles can cause poor cycle stability. To solve this, a carbon-coated silicon/carbon nanofiber (Si/C@C) composite with a ‘sandwich’ structure is constructed by hydrothermal reaction of glucose and an electrospun silicon/carbon nanofiber, followed by high-temperature carbonization. The effects of the thickness of the carbon coating layer and calcining temperature on the electrochemical performance are studied. The results showed that carbon is uniformly and continuously coated on the surface of the composite fibers, which avoid direct exposure of precipitated silicon on the surface of the nanofibers to the electrolyte, reduce the occurrence of side reactions and is conducive to the stable formation of SEI films. At the same time, the carbon shell inhibit the volume expansion of silicon to a certain extent and improve the conductivity of the composites. Consequently, the obtained Si/C@C exhibit good rate performance and cycle stability. With the optimised carbon coating thickness and calcination temperature, the obtained electrodes deliver a reversible capacity of 1120 and 683 mA h g^-1 at a current density of 0.1 and 2 A g^-1 respectively, and a specific capacity of 602 mAh∙g^-1 at a current density of 1 A g^-1 after 100 cycles, a capacity retention rate of 80%. The facilely synthesised Si/C@C composite shows potential applications in high-capacity silicon-based anode materials.     

Nanoparticles constructed mesoporous coral-like Mn2O3 as high performance anode for lithium-ion batteries

As well established, the morphology and architecture of electrode materials greatly contribute to the electrochemical properties. Herein, a novel structure of mesoporous coral-like manganese (III) oxide (Mn₂O₃) is synthesized via a facile solvothermal method coupled with the carbonization under air. When fabricated as anode electrode for lithium-ion batteries (LIBs), the as-prepared Mn₂O₃ exhibits good electrochemical properties, showing a high discharge capacity of 1090.4 mAh g^?1 at 0.1 A g^?1, and excellent rate performance of 410.4 mAh g^?1 at 2 A g^?1. Furthermore, it maintains the reversible discharge capacity of 1045 mAh g^?1 at 0.1 A g^?1 after 380 cycles, and 755 mAh g^?1 at 1 A g^?1 after 450 cycles. The durable cycling stability and outstanding rate performance can be attributed to its unique 3D mesoporous structure, which is favorable for increasing active area and shortening Li⁺ diffusion distance.     

高分散SiO2/石油沥青基多孔碳用于锂离子电池负极

二氧化硅(SiO₂)作为锂离子电池负极材料具有理论容量高、放电电位低、成本较低等特点,但存在导电性差、充放电过程体积膨胀严重以及容量衰减过快等问题。以石油沥青为碳源,利用硅烷偶联剂KH-540对纳米α-Fe₂O₃模板剂进行表面化学包覆,然后将硅源修饰模板剂与碳源混合,经碳化、酸洗等步骤得到高分散SiO₂/石油沥青基多孔碳(SiO₂/PC)。所得SiO₂/PC作为锂离子电池负极材料,在1 A·g^-1电流密度下,循环900圈后仍具有640 mA·h·g^-1的高可逆比容量。研究结果表明,高度纳米化的SiO₂在高温碳化过程原位生成,紧密牢固地负载于多孔碳表面,提高了其导电性,同时能够有效缓解SiO₂在充放电过程中的体积膨胀,抑制SiO₂的团聚或粉化,从而表现出优异的电化学性能。     

Fabrication of NiO-ZnO/RGO composite as an anode material for lithium-ion batteries

NiO-ZnO/RGO composite was obtained by the annealing of an Ni (OH)₂-Zn (OH)₂/RGO precursor, which has been fabricated by in situ ultrasonic agitation. Moreover, the NiO-ZnO nanoflakes are evenly distributed on the RGO sheets based on the scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization results. When the NiO-ZnO/RGO composite was used as an anode material in lithium-ion batteries (LIBs), the electrodes exhibited a high reversible capacity of 1017 mA h/g at a current density of 100 mA/g after 200 cycles and a specific capacity of 458 mA h/g at 500 mA/g even after 400 cycles. The electrode even reached a capacity of 185 mA h/g at a current density of 2000 mA/g. The excellent electrochemical properties of the NiO-ZnO/RGO composite might be attributable to the NiO-ZnO nanoflakes offering rich electrochemical reaction sites and shortening the diffusion length for lithium ion (Li⁺), as well as the RGO sheets improving the transfer rates of Li⁺ and electron during the charge-discharge process.     

碳纤维制品结构分析及其用作锂离子电池负极材料性能研究

通过X-射线衍射(XRD)和N2-BET法对材料结构进行分析,研究了其结构及用作锂离子电池负极材料的性能。结果表明,在一定范围内碳材料的容量与其层间距成正比关系;比表面积的大小与材料的容量有一定的关系;中孔率的提高有利于碳材料容量的增加。     

Investigating the effect of the degree of cross-linking in styrene butadiene rubber on the performance of graphite anodes for the use in lithium-ion batteries

Carboxymethyl cellulose/styrene butadiene rubber (CMC/SBR) has been proven to be an effective binder system for the use of graphite anodes within the lithium-ion battery industry. However, often when this system is employed, there is no acknowledgement regarding the specific chemistry of the SBR used. This is an important omission because properties such as glass transition temperatures and tensile strengths are heavily dependent on the ratio of styrene to butadiene content and the degree of cross-linking within the SBR. In this study, we investigate the impact of using styrene butadiene rubbers (SBRs) with different degrees of cross-linking on the performance of graphite anodes. We demonstrate that SBRs with a higher degree of cross-linking provide longer and more stable capacity retentions, than SBRs with a lower degree of cross-linking. This was found to correlate with the adhesion and cohesion strengths of the electrode coatings, and the degree of electrolyte swelling the SBRs systems undertook. Overall, the findings from this study indicate that the degree of cross-linking within the SBR impacts the overall performance of the battery.     

Preparation,structural, and characterizations of SnO2-coated TiNb2O7 anode materials for lithium-ion batteries

SnO₂-coated TiNb₂O₇ powders were synthesized via the solution coating method in the present research. The SnO₂ layers with a thickness of 3–5 nm were homogeneously coated on the surface of TiNb₂O₇ particles. TiNb₂O₇ coated with SnO₂ of 5 mol% with high Li⁺ diffusion coefficient delivered the discharge capacity of 319.5 mAh/g, which was 6.6% higher than that of the non-coated samples. The enhancement of capacity for the coated TiNb₂O₇ was owing to the low charge-transfer resistance of 17.5 Ω in contrary to the non-coated TiNb₂O₇ (27.8 Ω). SnO₂-coated TiNb₂O₇ possessed an improved capacity retention of 85.2% at 5 C after 100 cycles, superior to the non-coated TiNb₂O₇ (79.8%). On the other hand, the excessive amounts of SnO₂ coating led to the reduction in the capacity of the prepared samples. The excessive amounts of SnO₂ layers suppressed the Li⁺ diffusion and increased the charge-transfer resistance. The obtained results in this study indicated that coating of TiNb₂O₇ with appropriate amounts of SnO₂ significantly improved the electrochemical performance of TiNb₂O₇.     

Preparation and electrochemical performance of flower-like hematite for lithium-ion batteries

Flower-like hematite (α-Fe₂O₃) has been successfully prepared by heat-treatment from the iron(III)-oxyhydroxide precursor, which is obtained by the hydrolysis of FeCl₃ solution in the presence of NaClO. In this process, no templates or catalysts are required. SEM and TEM characterizations confirm that micro-flowers are composed of several dozen self-assembled nanopetals with the thickness of about 20 nm. On the basis of the morphology investigations in time-dependent experiments, the possible growth mechanism of the flower-like α-Fe₂O₃ is proposed, which is similar to a two-stage growth process. Furthermore, as an anode electrode material for rechargeable lithium-ion batteries, the flower-like α-Fe₂O₃ exhibits excellent electrochemical performance, which can be attributed to the high surface area induced by the flower-like structure, the short lithium diffusion length and the restriction of volume change of the Li⁺ insertion/extraction.     

Electrochemical performance of flowerlike CaSnO3 as high capacity anode material for lithium-ion batteries

Nanosized CaSnO₃ is synthesized by a hydrothermal process and characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The SEM observation shows the sample has a porous flowerlike morphology. The electrochemical results exhibit that the stable and reversible capacity of 547 mAh g⁻¹ is obtained after 50 cycles at 60 mA g⁻¹ (0.1 C) and the corresponding charge capacity is determined to be 316 mAh g⁻¹ at the current density of 2.5 C. Cyclic voltammetry and electrochemical impedance spectroscopy data are analyzed to complement the galvanostatic results. The observed excellent performance is attributed to the porous structure and large surface area of flowerlike CaSnO₃.     

退役锂离子电池中有价金属回收研究进展

锂离子电池被广泛应用于电子产品、电动汽车和大规模储能材料等多个领域。随着电动车市场的快速发展,其使用量还将显著增加,随之产生数量极大的退役锂离子电池。退役锂离子电池的回收利用可以避免环境污染和资源浪费,尤其对实现锂资源供需平衡具有重要意义。综述了退役锂离子电池中有价金属元素回收技术研究现状,探讨了该领域未来发展方向。电池安全高效拆解技术与装备、有价元素整体化回收技术、电极材料再制备工艺以及避免二次污染环境是未来退役锂离子电池循环利用领域值得关注的重点。