Insight into effects of graphene and zinc oxide in Li4Ti5O12 as anode materials for Li-ion full-cell battery

Programmable design of nanocomposites of Li₄Ti₅O₁₂ (LTO) conducted through hydrothermal route in the presence of ethylenediamine as basic and capping agent. In this work, effect of ZnO and Graphene on the Li₄Ti₅O₁₂ based nanocomposites as anode materials investigated for Li-Ion battery performances. The full cells battery assembled with LTO based nanocomposites on Cu foil as the anode electrode and commercial LMO (LiMn₂O₄) on aluminum foil as cathode electrode. X-Ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), along with Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission electron microscopy (TEM) images was applied for study the composition and structure of as-prepared samples. The electrochemical lithium storage capacity of prepared nanocomposites was compared with pristine LTO via chronopotentiometry charge-discharge techniques at 1.5–4.0 V and current rate of 100 mA/g. As a result, the electrode which is provided by LTO/TiO₂/ZnO and LTO/TiO₂/graphene nanocomposites provided 765 and 670 mAh/g discharge capacity compared with pristine LTO/TiO₂ (550 mAh/g) after 15 cycles. Based on the obtained results, fabricated nanocomposites can be promising compounds to improve the electrochemical performance of lithium storage.     

TiF3 catalyzed MgH2 as a Li/Na ion battery anode

MgH₂ has been considered as a potential anode material for Li ion batteries due to its low cost and high theoretical capacity. However, it suffers from low electronic conductivity and slow kinetics for hydrogen sorption at room temperature that results in poor reversibility, cycling stability and rate capability for Li ion storage. This work presents a MgH₂–TiF₃@CNT based Li ion battery anode manufactured via a conventional slurry based method. Working with a liquid electrolyte at room temperature, it achieves a high capacity retention of 543 mAh g^?1 in 70 cycles at 0.2 C and an improved rate capability, thanks to the improved hydrogen sorption kinetics with the presence of catalytic TiF₃. Meanwhile, the first realization of Na ion uptake in MgH₂ has been evidenced in experiments.     

Technology progress of cathode materials for lithium ion batteries

本文针对商业化锂离子电池正极材料,介绍了钴酸锂、镍钴锰三元材料、尖晶石锰酸锂、磷酸铁锂等正极材料的优缺点、市场现状,以及我国正极材料的技术和产业现状。对行业存在的共性问题,如产品品质差,技术实力不足进行了分析。展望了产业未来发展趋势,并提出了增加技术投入、加强产学研协同和高端装备应用等建议。     

Mesoporous carbon-encapsulated NiO nanocomposite negative electrode materials for high-rate Li-ion battery

In this study, a novel mesoporous carbon-encapsulated NiO nanocomposite is proposed and demonstrated for Li-ion battery negative electrode. The nanostructure of the electrode composes of an ordered mesoporous CMK-3 as a 3D nanostructured current collector with micorporous channels for Li⁺ transportation. In addition, exclusive formation of NiO nanoparticles in the confined space of the ordered mesoporous carbon is achieved using the hydrophobic encapsulation route. The half-cell assembled with the synthesized NiO/CMK-3 nanocomposite is able to deliver a high charge capacity of 812 mAh g⁻¹ at the first cycle at a C-rate of 1000 mA g⁻¹ and retained throughout the test with only 0.236% decay per cycle. Even the C-rate as high as 3200 mA g⁻¹, a charge capacity of 808 mAh g⁻¹ contributed by the NiO nanoparticles in CMK-Ni is obtained, which shows excellent rate capability for NiO with utilization close to 100%. The result suggests fast kinetics of conversion reaction for NiO with Li⁺. It also indicates the blockage of the pore channels by NiO nanoparticles does not take place in the synthesized NiO/CMK-3.     

Research progress on safety of lithium ion battery electrolyte

锂离子电池的能量密度及其安全问题是限制其在电动汽车应用中的主要障碍。随着能量密度的不断提升,当务之急是有效解决锂离子电池的安全性问题。锂离子电池安全问题本质上与当前电解液中使用的高挥发性、易燃的有机溶剂有关。因此,本文主要从电解液的燃烧性角度,介绍了电解液在锂离子电池材料安全性方面的研究现状,包括阻燃添加剂、不燃性氟代有机溶剂、高浓度电解液及固液混合电解质的应用等,分析其对安全性能提升的机理,并对电解液的发展方向进行了展望。     

热电池电极材料的研究现状及展望

锂系热电池因具有激活时间短、放电时间长、高比能量和高比功率等特点成为热电池的主导产品。目前对锂系热电池的研究主要集中在电极材料和电解质上,很少有系统综述锂系热电池电极材料的相关文献。本文着重阐述了锂系热电池的阳极材料和阴极材料(硫化物、氧化物和氯化物)的研究现状,并对其未来的发展方向提出了展望。     

Research of toxic productions from thermal runaway processes of Li-ion battery and materials

本文阐述了锂离子电池常规安全性问题和热失控引发燃烧爆炸泄漏毒物的非常规安全性问题,探讨了锂离子电池泄露物的毒性及其对人体和环境的危害,以电动车用锂离子电池为例分析了城市交通和环境将面临的继发问题和压力,定量对比了10 A·h软包装的磷酸铁锂、锰酸锂和三元材料锂离子电池热失控燃烧释放的代表性毒物之一的CO浓度,提出了锂离子电池热失控毒物安全性问题的不可回避性。     

Research progress in the consistency screening of Li-ion batteries

锂离子电池因综合性能优良,近年来在移动储能和固定储能领域的应用发展迅速。当多个单体电池通过串并联组成电池模组时,不仅电池组的能量低于电池单体能量的加和,电池组的寿命也明显低于单体电池的水平。除了电池运行环境不均匀（如温度场）外,电池组内部电池单体之间微小的不一致性也是造成电池组性能快速衰减的主要原因。依据电池组的结构建立电池一致性的筛选方法和标准,是目前锂离子电池模组研究中亟待解决的关键技术。本文回顾了近年来国内外锂离子电池一致性筛选方法研究领域的进展,对锂离子电池一致性的内涵进行了剖析,并重点对串联筛选方法进行了评述。     

Influence of graphite anode binder on the high power Li-ion battery performance

本文研究了油性体系的聚偏氟乙烯（PVDF）和水溶性体系的丁苯橡胶和羧甲基纤维素钠（SBR-CMC）对于动力锂离子电池性能的影响。通过差示扫描量热法（DSC）测试了PVDF、SBR以及CMC的玻璃化转变温度,结果分别为-51.7℃、-42.18℃和-55.82℃。通过软包装试验电池,对比了两种黏结剂对于动力锂离子电池性能包括化成分容、大倍率放电、低温放电以及循环性能等的影响。结果发现,两种黏结剂体系的试验电池在常温下的容量发挥、功率性能以及循环寿命没有明显区别,但是在低温（-40℃）的放电性能的差别较大,并且随着放电电流加大,这种差别会进一步增大。分别在20℃和-40℃下以0.5 C放电、在-40℃下1 C放电,水性黏结剂体系电池与油性体系电池放电容量比分别为1.004、0.706和0.589。     

Quantifying tortuosity in porous Li-ion battery materials

An accurate assessment of liquid-phase mass transport resistances is necessary for understanding and optimizing battery performance using mathematical models. This work combines modeling and experiments to quantify tortuosity in electrolyte-filled porous battery structures (separator and active-material film). Tortuosities of separators were measured by two methods, AC impedance and polarization-interrupt, which produced consistent results. We measured an apparent interfacial resistance at the lithium metal electrodes that contributed to both ohmic and diffusional resistance of the cell. The polarization-interrupt experiment was used similarly to measure effective electrolyte transport in porous films of cathode materials, particularly films containing LiFePO₄. An empirical relationship between porosity and the tortuosity of the porous structures was developed. Our results demonstrate that the tortuosity-dependent mass transport resistance in porous separators and electrodes is significantly higher than that predicted by the oft-used Bruggeman relationship.     

Research progress on cathode materials for high energy density lithium ion batteries

便携式电子设备的微型化、轻量化与电动汽车、电网储能设备的飞速发展,对高能量密度的锂离子电池的研发和性能表现提出了越来越高的要求。锂离子电池正极材料是锂离子电池的核心,其提供锂离子并参与电化学反应,因此改善正极材料性能是提高锂离子电池能量密度的关键。人们需要进一步研究开发成本较低、安全性更好的高能量密度新型锂离子电池正极材料。本文主要从提升正极材料的比容量和工作电压两方面介绍三元、富锂锰基材料和高电位镍锰酸锂等高比能量正极材料的介尺度结构设计、制备与性能调控研发进展。     

Research progress on the nano-Si/C materials with high capacity for Lithium-iom battery

纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料（380～450 mA·h/g）的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料（500～2000 mA·h/g）方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。     

The technical route exploration of lithium ion battery with high safety and high energy density

发展高比能动力锂离子电池是新能源汽车,特别是纯电动汽车实现长续航里程的关键手段之一,然而,随着电池能量密度的不断提高,电池的循环寿命和安全性能就会受到影响。本文以能量密度300W·h/Kg单体电池为对象,从材料体系的选择、电芯结构设计以及系统安全防护措施等多维度展开论述,探究了高安全高比能动力锂离子电池系统技术路线。     

Progress on high energy density lithium batteries by CAS battery research group

提高动力电池的能量密度将显著延长续航里程,对发展电动汽车具有重要的意义.中国科学院在2013年底部署了中国科学院战略性先导科技专项,通过合作研究,积极探索了第三代锂离子电池,固态锂电池,锂-硫电池和锂-空气电池等电池体系.其中,采用纳米硅碳负极,富锂正极的24 A·h的锂离子电池单体,质量能量密度达到374 W·h/kg,体积能量密度达到577 W·h/L.8 A·h固态聚合物锂电池60 ℃下能量密度达到240 W·h/kg,基于无机陶瓷固态电解质的固态锂电池室温下能量密度达到240 W·h/kg.37 A·h的锂硫电池单体室温能量密度达到566 W·h/kg,50 ℃达到616 W·h/kg.5 A·h锂空气电池单体能量密度达到526 W·h/kg.目前这些样品电池在综合技术指标方面离实际应用还有较大的距离,需要进一步深入细致的进行基础科学与关键技术方面的研究.从长远考虑,电池能量密度的提高必然进一步增加电池安全性风险,因此不同形式的固态锂电池将是未来长续航动力锂电池的发展方向.     

Transmission electron microscopy of lithium ion battery materials

理解材料的构-效关系是功能材料领域的永恒话题,在锂离子电池材料的研究中亦是如此。因此可以看到如X射线衍射、中子衍射、核磁共振、X射线电子能谱等结构表征手段被应用于锂离子电池材料的研究中。但是因上述方法对于微观局域结构并不敏感,而给出平均的结构信息。材料的性能往往随微观结构的不同而天差地别,因此获取锂离子电池材料的微观结构信息十分重要。透射电子显微镜具有原子尺度的空间分辨能力,可以获取原子尺度上的结构扭曲和电子结构变化,在锂离子电池材料的研究中起到了至关重要的作用。本文从电子显微学和锂离子电池材料的关系入手,从基本原理和实验方法出发,为相关领域科研人员提供便利。     

Research progress on the Li-excess Mn-based cathode materials with high capacity for lithium-ion battery

富锂锰基正极材料因具有高的放电比容量,有望成为下一代400 W·h/kg动力电池最有前景的正极材料。本文简要介绍了本研究团队在富锂锰基正极材料方面的研究进展。通过团队多年研发,材料的首次不可逆容量、倍率性能、循环稳定性得到明显的改善,而且,电压衰减被有效的抑制。同时,研制出基于富锂锰基正极材料和纳米硅碳负极材料的新型24A·h高容量锂离子电池,其质量能量密度达到374 W·h/kg,体积能量密度达到  577 W·h/L。     

Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separators

Static and dynamic thermomechanical analysis was performed with a dynamic mechanical analyzer (DMA) to identify thermal and mechanical transitions for commercially available polymer separators under mechanical loading. Clear transitions in deformation mode were observed at elevated temperatures. These transitions identified the onset of separator “shutdown” which occurred at temperatures below the polymer melting point. Mechanical loading direction was critical to the overall integrity of the separator. Anisotropic separators (Celgard 2320, 2400 and 2500) were mechanically limited when pulled in tensile in the transverse direction. The anisotropy of these separators is a result of the dry technique used to manufacture the micro-porous membranes. Separators prepared using the wet technique (Entek Gold LP) behaved more uniformly, or biaxially, where all mechanical properties were nearly identical within the separator plane. The information provided by the DMA can also be useful for predicting the long-term durability of polymer separators in lithium-ion batteries exposed to electrolyte (solvent and salt), thermal fluctuations and electrochemical cycling. Small losses in mechanical integrity were observed for separators exposed to the various immersion environments over the 4-week immersion time.     

Compatibility of LiCoO2 and LiMn2O4 cathode materials for Li0.55La0.35TiO3 electrolyte to fabricate all-solid-state lithium battery

In order to improve performance of all-solid-state lithium ion battery with honeycomb structure, a compatibility of two commonly used cathode materials, LiCoO₂ and LiMn₂O₄, to Li_0.55La_0.35TiO₃ (LLT) solid electrolyte was studied. LiCoO₂/honeycomb LLT and LiMn₂O₄/honeycomb LLT half cells were fabricated by the impregnation of mixture of the cathode material with its precursor sol into honeycomb holes followed by the calcination. Impurity phases were observed at interface between LiCoO₂ and honeycomb LLT, while no impurity phase was confirmed in the case of LiMn₂O₄. In half cell test, the LiMn₂O₄/honeycomb LLT cell showed about 6 times larger discharge capacity than the LiCoO₂/honeycomb LLT cell, because of high internal resistance of the LiCoO₂/honeycomb LLT cell caused by the impurity phases. It can be said that the formation of low resistance interface at active material/electrolyte is one of the most important key to improve performance of the all-solid-state battery. Using LiMn₂O₄ instead of LiCoO₂, better interface between cathode material and LLT was obtained.     

Recent progress on vanadium flow battery technologies

全钒液流电池因其安全可靠,使用寿命长,环境友好,电池均匀性好,可实时直接监测其充放电状态等特点,已成为规模储能技术领域的重要设备.本文详细分析了全钒液流电池的产业化挑战,从而提出主要技术发展方向.另外,重点对中国科学院大连化学物理研究所和大连融科储能技术发展有限公司合作团队在电堆,电池系统和应用示范方面的最新进展进行了总结.     

A novel structure of ceramics electrolyte for future lithium battery

In order to fabricate large scale all-solid-state Li battery, we suggested a novel structure of solid electrolyte, which is composed of porous electrolyte supported by honeycomb-type electrolyte. A possibility of fabrication of the honeycomb-supported porous electrolyte and a compatibility of this structure with all-solid-state battery were examined using LLT (Li_0.35La_0.55TiO₃) solid electrolyte which is one of the anticipated solid electrolytes due to its high Li ion conductivity. A porous layer membrane with 3 dimensionally ordered (3DOM) macroporous structure was prepared by a colloidal crystal templating method. The porous honeycomb was fabricated by pushing the membrane into holes of honycomb using a needle followed by calcination. The 3DOM membrane and honeycmb electrolyte were sintered well each other. After filling the 3DOM pores with LiMn₂O₄ cathode material, the compatibility of this novel porous honeycomb electrolyte with all-solid-state battery was examined. The LiMn₂O₄/porous honeycomb cell clearly demonstrated charge and discharge behaviors, indicating the porous honeycomb structure can be applied to the all-solid-state battery. The discharge capacity was 71 mA h g⁻¹ (1.3 mA h cm⁻²) at 30 °C.