锂离子电池硅-碳负极材料的研究进展

硅因具有大的比容量,极有希望成为下一代锂离子电池的主要负极材料。硅基负极材料工业化需其具备较高的比容量、良好的循环性能并能够进行工业生产。综述了硅-碳复合材料的研究进展,介绍了各类硅-碳复合物的制备方法、结构和电化学性能,提出制备低成本、性能稳定的硅-碳复合物将成为硅基材料研究的主导方向。     

锂离子电池硅碳负极材料的制备及其结构设计研究进展

硅基材料理论容量高、电位低、自然资源丰富，是最理想的锂离子电池负极材料。但是硅基负极在锂化和脱锂过程中巨大的体积变化，导致了硅基负极的循环稳定性与导电性差，阻碍了其实际应用。硅碳复合材料可将碳材料的高导电性和机械性能与硅基材料的高容量和低电位的优势相结合。综述了硅碳负极材料的主要制备方法，总结了硅碳复合材料的结构设计，并对未来碳硅材料的研究工作进行了展望。     

锂离子电池硅基负极材料研究进展

硅基负极材料具有比容量大的优点,是高容量锂离子电池理想的负极材料。然而硅基材料在循环过程中容量衰减快,影响了其实用性。从硅复合物粉末和硅薄膜两个重要研究方面对硅基负极材料进行了综述,指出在Si基复合负极材料的研究中,单一途径改性提升循环性能的幅度有限,很难达到实用化阶段。硅的纳米化、无定形化、合金化及复合化等方法的综合运用成为硅基材料研究的主导方向。     

硅材料在锂离子电池中的应用研究进展

硅材料作为锂离子电池负极材料具有比容量大的优点,是高容量锂离子负极材料的研究热点之一.综述了近年来锂离子电池硅负极材料的研究进展.分别对硅及含硅材料作为锂离子电池负极材料的发展过程、充放电特性、储锂机理及影响其储锂的各因素进行了分析和总结,并对其存在的问题进行了分析.探讨了采用不同复合物、不同制备方法和合成硅化物等改性方法来提高其循环性能的可行性.指出纳米硅基复合物将是硅负极材料最有希望的发展方向.     

锂离子电池硅-碳负极材料的研究进展

硅基负极材料因具有较高的理论储锂容量,将替代传统的石墨负极材料成为下一代锂离子电池最有前景的负极材料之一。然而,硅作为负极材料体积膨胀率(可达到300%)大、导电率低、易被电解液分解产生的HF腐蚀,这些缺点限制了其在商业应用中的发展。碳具有稳定性高、导电性好、价格低、来源广等优点,但其理论储锂容量较低,仅约为硅的1/10。为解决锂离子电池硅材料存在的问题,目前主要采用将硅与碳进行复合的办法,制备出储电量高、导电性好、循环性能优异的硅-碳复合负极材料。重点从硅碳复合结构和制备方法两个方面阐述了硅-碳复合负极材料的研究进展,认为"鸡蛋"结构能够有效地提高循环性能和安全性能,但是目前仍然不能够规模化生产。最后提出研究发展思路,应用胶体颗粒共凝胶法设计制备了一种特殊的硅-碳复合核壳结构。     

锂离子电池硅基负极材料的研究进展

硅负极材料具有很高的理论比容量(4200mAh/g),但充放电过程中巨大的体积变化导致其循环性能很差,同时较低的电导率以及与常规电解液的不相容性等因素限制了硅作为负极材料在锂离子电池中的应用。因此,目前大部分研究人员都致力于解决其循环性能差的问题。综述了近年来改善硅基负极材料性能的最新进展,指出了硅基材料作为锂离子电池负极材料的研究前景。     

源于溪木贼的高性能锂离子电池三维多孔生物质硅/碳复合负极材料

锂离子电池硅基负极材料的理论比容量比传统石墨材料高10倍, 是最有前途的锂离子电池负极材料之一。然而硅基纳米材料的制备工艺复杂、成本高昂, 严重限制了锂离子电池硅负极的商业应用。本工作采用溪木贼为原料, 通过深度还原、浅度氧化和碳包覆工艺制备了三维多孔生物质硅/碳复合材料(多孔3D-bio-Si/C)。三维多孔结构不仅有利于Li⁺的快速传输, 而且提供足够的空隙缓解在脱-嵌锂过程中发生的体积变化。得益于三维结构中大量的孔隙和高强度的外部碳层, 多孔3D-bio-Si/C制备的电极表现出优异的电化学性能。当电流密度为1 A/g时, 多孔3D-bio-Si/C的可逆容量为1243.2 mAh/g, 循环400次后仍可保持933.4 mAh/g, 容量保持率高达89%。利用溪木贼作为生物质硅源制备高性能硅基负极材料, 实现了低成本、可规模化、绿色和可持续的合成路线, 有望为Si基锂离子电池负极材料的商业应用打下基础。     

锂离子电池用硅/石墨/碳复合负极材料的电化学性能

采用湿法混料及高温热解法制备了锂离子电池用硅/石墨/碳复合负极材料,并研究了不同配方的复合材料结构及电化学性能。研究发现,硅含量为20%(质量分数)时,复合材料首次可逆容量为865mAh/g,循环30次后仍为757mAh/g,容量保持率可达88%,大大改善了硅基材料作为锂离子电池负极材料的电化学性能。     

锂离子电池硅基负极用粘结剂的设计改性进展

发展锂离子电池是缓解当前能源和环境问题的有力措施,但其能量密度已无法满足未来储能装置的高要求。发展高比能量型锂离子电池必须从提高电极材料的性能入手。硅基材料具有容量高、成本低、平台电压低等优点,被认为是最具潜力的负极材料。然而,该类材料在充放电过程中会发生巨大的体积变化(300%),导致电池容量下降严重甚至失效。近年来,研究者们开始着眼于通过对电极中的粘结剂进行结构设计和复合改性来提升硅基负极的性能,并取得了显著的效果。基于硅基负极目前存在的问题,总结了适用于硅基负极的粘结剂类型,并从粘结剂分子链结构设计和增强电极微粒间作用力这两个方面综述了近年来硅基负极中粘结剂的设计改性进展,最终展望了硅基负极用粘结剂的发展趋势和未来前景。      

锂离子电池锡基负极材料研究进展

介绍了锂离子电池锡基负极材料的反应机理、制备方法、电化学性能及近期的研究现状.锡基负极材料具有高的可逆容量,制备工艺简单,若能克服目前存在的问题,将有望成为新一代锂离子电池负极材料.     

锂离子电池聚阴离子型硅酸盐正极材料的研究进展

综述了硅酸盐正极材料的设计、特性、制备及电化学性能,介绍了基于密度泛函理论的量子化学计算在锂离子电池材料设计中的方法和理论,认为进一步开展Li2MSiO4及其复合材料的理论和实验研究可以获得性能优异的高容量正极材料.     

软化学法合成正交结构LiMnO_2及其电化学性能

研究以氢氧化锂和三氧化二锰为原料,用软化学法制备具有正交结构的锂离子电池正极材料LiMnO2。用X射线衍射法确定了材料的结构,用扫描电镜考察了材料形貌和反应时间的关系,观察结果显示得到的LiMnO2的粒子尺寸在300~500nm。结合循环伏安法和交流阻抗分析研究了合成条件对材料组织结构、尺寸与电化学性能的影响。材料的电化学性能测试结果表明,合成的正交扭曲结构LiMnO2(o-LiMnO2)材料在电化学过程中初期表现了较好的电化学性能。但材料在电化学过程中逐步向尖晶石结构相LiMn2O4转变,容量产生衰减,其循环寿命有待更进一步改善。     

LiFePO_4锂离子电池容量的衰减机制

为探讨LiFePO4锂离子电池容量衰减、电池循环性能失效的原因,对LiFePO4锂离子电池进行循环性能测试,通过拆解电池,采用X射线衍射、扫描电子显微镜结构测试手段,对多次充、放电循环前后锂离子电池LiFePO4正极材料和石墨负极材料的物理性能进行表征。结果表明,石墨负极在200次循环后,衍射峰的位置略微右移,晶体粒径结构几乎没变化,但是LiFePO4正极材料的晶体结构却发生不可逆变化,晶粒从3.73 nm减小到2.75 nm;在0.25 C倍率下循环200次,容量衰减11.6%;随着循环次数的增加,LiFePO4正极材料微观结构和晶粒度细化造成Li+传输阻力增大,是造成LiFePO4锂离子电池容量衰减的主要原因。     

锂离子电池高镍三元材料的研究进展

用于锂离子电池的高镍三元材料由于成本低、能量密度高、可逆容量高、环境友好等优点,是现在以及未来车用动力电池首选正极材料。本文在综述了高镍三元材料的晶体结构特性和电化学特性的基础上,介绍了国内外主要制备方法、掺杂以及包覆等改性措施,重点讨论了不同种类包覆材料对高镍三元倍率性能、循环性能和高温稳定性能的影响。最后,针对高镍三元电解液、安全性、压实密度及循环寿命等问题进行分析与展望。     

A High‐Capacity O2‐Type Li‐Rich Cathode Material with a Single‐Layer Li2MnO3 Superstructure

A high capacity cathode is the key to the realization of high‐energy‐density lithium‐ion batteries. The anionic oxygen redox induced by activation of the Li₂MnO₃ domain has previously afforded an O3‐type layered Li‐rich material used as the cathode for lithium‐ion batteries with a notably high capacity of 250–300 mAh g^?1. However, its practical application in lithium‐ion batteries has been limited due to electrodes made from this material suffering severe voltage fading and capacity decay during cycling. Here, it is shown that an O2‐type Li‐rich material with a single‐layer Li₂MnO₃ superstructure can deliver an extraordinary reversible capacity of 400 mAh g^?1 (energy density: ≈1360 Wh kg^?1). The activation of a single‐layer Li₂MnO₃ enables stable anionic oxygen redox reactions and leads to a highly reversible charge–discharge cycle. Understanding the high performance will further the development of high‐capacity cathode materials that utilize anionic oxygen redox processes.     

Enhanced cycling performance and high energy density of LiFePO4 based lithium ion batteries

LiFePO₄ attracts a lot of attention as cathode materials for the next generation of lithium ion batteries. However, LiFePO₄ has a poor rate capability attributed to low electronic conductivity and low density. There is seldom data reported on lithium ion batteries with LiFePO₄ as cathode and graphite as anode. According to our experimental results, the capacity fading on cycling is surprisingly negligible at 1664 cycles for the cell type 042040. It delivers a capacity of 1170 mAh for 18650 cell type at 4.5C discharge rate. It is confirmed that lithium ion batteries with LiFePO₄ as cathode are suitable for electric vehicle application.     

锂离子二次电池多孔集流体的制备与应用

金属基负极材料具有超高的理论容量,是新一代锂离子二次电池理想的负极材料。但是,金属基负极材料在充放电过程中会产生严重的体积膨胀,从而导致负极材料的粉化和脱落,使其循环性能迅速恶化。采用多孔集流体能够充分利用三维连通的孔隙和高的比表面积来显著提高锂离子二次电池的循环性能和能量密度,是缓解金属基负极材料体积膨胀的有效方法之一。本文总结了近年来微米多孔、纳米多孔和双尺度多孔集流体的制备方法及其在锂离子二次电池中的应用。     

Mesoporous Germanium Anode Materials for Lithium‐Ion Battery with Exceptional Cycling Stability in Wide Temperature Range

Porous structured materials have unique architectures and are promising for lithium‐ion batteries to enhance performances. In particular, mesoporous materials have many advantages including a high surface area and large void spaces which can increase reactivity and accessibility of lithium ions. This study reports a synthesis of newly developed mesoporous germanium (Ge) particles prepared by a zincothermic reduction at a mild temperature for high performance lithium‐ion batteries which can operate in a wide temperature range. The optimized Ge battery anodes with the mesoporous structure exhibit outstanding electrochemical properties in a wide temperature ranging from ?20 to 60 °C. Ge anodes exhibit a stable cycling retention at various temperatures (capacity retention of 99% after 100 cycles at 25 °C, 84% after 300 cycles at 60 °C, and 50% after 50 cycles at ?20 °C). Furthermore, full cells consisting of the mesoporous Ge anode and an LiFePO₄ cathode show an excellent cyclability at ?20 and 25 °C. Mesoporous Ge materials synthesized by the zincothermic reduction can be potentially applied as high performance anode materials for practical lithium‐ion batteries.     

Novel size and surface oxide effects in silicon nanowires as lithium battery anodes

With its high specific capacity, silicon is a promising anode material for high-energy lithium-ion batteries, but volume expansion and fracture during lithium reaction have prevented implementation. Si nanostructures have shown resistance to fracture during cycling, but the critical effects of nanostructure size and native surface oxide on volume expansion and cycling performance are not understood. Here, we use an ex situ transmission electron microscopy technique to observe the same Si nanowires before and after lithiation and have discovered the impacts of size and surface oxide on volume expansion. For nanowires with native SiO(2), the surface oxide can suppress the volume expansion during lithiation for nanowires with diameters <～50 nm. Finite element modeling shows that the oxide layer can induce compressive hydrostatic stress that could act to limit the extent of lithiation. The understanding developed herein of how volume expansion and extent of lithiation can depend on nanomaterial structure is important for the improvement of Si-based anodes.     

Composites of graphene and encapsulated silicon for practically viable high-performance lithium-ion batteries

A facile and scalable approach to synthesize silicon composite anodes has been developed by encapsulating Si particles via in situ polymerization and carbonization of phloroglucinol-formaldehyde gel, followed by incorporation of graphene nanoplatelets. As a result of its structural integrity, high packing density and an intimate electrical contact consolidated by the conductive networks, the composite anode yielded excellent electrochemical performance in terms of charge storage capability, cycling life and coulombic efficiency. A half cell achieved reversible capacities of 1,600 mAh·g^?1 and 1,000 mAh·g^?1 at 0.5 A·g^?1 and 2.1 A·g^?1, respectively, while retaining more than 70% of the initial capacities over 1,000 cycles. Complete lithium-ion pouch cells coupling the anode with a lithium metal oxide cathode demonstrated excellent cycling performance and energy output, representing significant advance in developing Si-based electrode for practical application in high-performance lithium-ion batteries.