高能量密度锂离子电池用富锂正极材料

随着移动通讯设备和电动汽车的发展,对高比能量密度锂离子电池的需求越来越大。目前商业化动力电池主要采用的磷酸铁锂和三元正极材料放电比容量均低于180 mAh/g,难以满足一次充电行驶500公里以上的要求,因此,正极材料的比容量已成为限制锂离子电池能量密度提高的瓶颈。富锂材料具有大的比容量(≥250 mAh/g)和高的放电电压(3.8 V),理论能量密度高达900 Wh/kg,是未来动力电池的理想正极材料,因而研究高比容量富锂正极材料具有非常重要的现实意义。本文回顾了锂离子电池正极材料的发展和目前商业化正极材料比容量低的现状,综述了新一代大比容量富锂正极材料的结构特征和电化学性质,以及放电机制和改性研究的最新进展,并指出现阶段高能量密度锂离子电池用富锂材料遇到的问题,且有针对性地提出了解决思路和方法。     

锂离子电池富锂材料中离子掺杂、表面包覆、表面氧空位修饰的作用机理及其联合机制

富锂层状氧化物材料是一种具有类固溶体结构的锂离子电池正极材料,放电比容量可达250 m Ah/g,且价格低廉。因此,富锂层状氧化物材料被认为是最有希望的下一代正极材料之一。然而,富锂层状材料还存在诸多问题,如首次库仑效率低、倍率性能差以及容量和电压平台衰减严重,这些问题阻碍其在商业中的应用。本文从富锂层状材料的晶型结构和首次充放电特性出发,主要介绍了离子掺杂、表面包覆以及表面氧空位修饰的作用机理,并进一步分析了不同掺杂离子和不同包覆材料作用于富锂层状材料后性能差异的原因,以及双掺杂和双包覆的优势。最后,本文针对单纯的离子掺杂、表面包覆、表面氧空位修饰在富锂层状材料改性中的不足,提出了基于上述三种改性方式的联合改性机制,并对该机制进行了简要介绍。     

富锂三元层状正极材料的研究进展

富锂三元层状正极材料(xLi₂MnO₃·(1-x)LiMO₂(0<x<1,M=Mn,Ni,Co))因其远高于其它正极材料的放电比容量而被视为下一代锂离子电池正极材料的最佳选择之一,是未来锂离子电池研究和发展的重点。 但由于其循环性能差、库伦效率低等缺陷,富锂正极材料迟迟不能实现商业化生产。 本文将介绍近几年国内外富锂三元层状正极材料的最新研究进展,主要包括富锂三元层状正极材料的组成、制备技术、结构和性能研究以及包覆与掺杂等改性方面的研究进展,同时对富锂层状正极材料未来的发展趋势和前景作了展望。     

锂离子电池用富锂层状正极材料

正极材料与负极材料是锂离子电池重要组成部分。目前锂离子电池负极材料比容量通常在300mAh/g以上,而正极材料比容量始终徘徊在150mAh/g。正极材料正在成为锂离子电池性能进一步提升的瓶颈。富锂层状正极材料是一类新型正极材料,其可逆容量在200mAh/g以上,其高容量特性引起人们的广泛关注。这类材料可以用xLi₂MO₃·(1-x)LiM'O₂ (M 为Mn, Ti, Zr之一或任意组合; M'为Mn, Ni, Co之一或任意组合; 0≤x≤1)形式表示。由于其组成与结构的特殊性,这类富锂层状正极材料的充放电机理也不同于其它含锂过渡金属氧化物正极材料。本文介绍富锂层状正极材料的合成、结构与充放电机理,重点介绍近年来通过改性提高其电化学性能方面的研究进展,指出目前富锂材料研究中存在的问题,探讨未来的研究重点。     

富锂层状氧化物正极材料:结构、容量产生机理及改性

锂离子电池作为新型的储能形式,缓解了人们对化石燃料的依赖和日益严峻的环境压力。富锂层状氧化物相比于传统正极材料,由于其低成本和大可逆容量的特性,被誉为最具发展潜力的下一代锂离子电池正极材料之一,尤其是在电动汽车和大规模储能电网领域的应用前景十分广阔。本文从材料的结构类型出发,主要介绍了固溶体结构和复合结构在晶格排布上的差异以及在鉴别这种差异时所采用的一系列表征手段。本文还总结了近年来提出的最具代表性的几种4.5V电压平台产生机理,从不同角度解释了富锂层状氧化物在首次循环过程中表现出异常容量的现象,并结合现有研究阐述了各种机理。此外,也对阻碍富锂层状氧化物进一步发展的重大问题,包括首次不可逆容量损失、循环性能和倍率性能等进行了分析,讨论了表面尖晶石相对材料性能的影响,介绍了几种最典型的改性手段。最后,对富锂层状氧化物正极材料未来的研究方向进行了概述,展望其研究前景。     

富锂锰基正极材料的表面改性研究进展

随着电动汽车和储能电站等电力设备的快速发展,对高能量密度的锂离子电池的需求日益增加.高比容量（>250 mAh·g^-1）的富锂锰基正极材料,有望成为锂离子电池实现高比能量（>350 Wh·kg^-1）的关键正极材料.富锂锰基正极材料的Li₂MnO₃相和晶格氧参与电化学反应使其拥有了高容量,但这也导致表面结构和成分容易发生变化,进而造成富锂锰基正极材料存在着诸如首次库伦效率低、倍率性能差和循环后电压和容量衰减严重等问题.因此,本文综述了富锂锰基正极材料的表面包覆、表面掺杂和表面化学处理三种表面改性方法,并进一步讨论了三种表面改性方法对材料性能提升的机制机理和优缺点.在此基础上,介绍了近些年基于多方法的表面联合改性工作.通过对富锂锰基正极材料进行表面联合改性,不仅可以改善其结构稳定性和抑制电极/电解液界面副反应,而且可以缓解其在循环过程中不断发生的结构转变和晶格氧的析出问题.最后,对富锂锰基正极材料表面改性研究方向进行了总结和展望.     

锂离子电池用富锂正极材料的研究进展

富锂材料xLi₂MnO₃·(1-x)LiMO₂（0-1）和低廉的价格已引起人们的广泛兴趣. 但其首次充放电循环的较大不可逆容量损失、较差的倍率性能和循环过程的材料相变等关键问题制约了其发展. 富锂材料结构解析和充放电机理探索一直是研究的热点. 目前,富锂材料是否为固溶体仍有争论,首次充电4.5 V平台的氧流失机理已得到确认. 为了提高富锂材料的电化学性能,可从体相掺杂、表面包覆和结构形貌控制等方面对材料进行改性,其电化学性能有显著提升. 本文综述了富锂材料最新研究进展,归纳了相关制备方法,重点介绍了富锂材料的结构特点、锂嵌脱机理和改性方法,并展望了今后的研究方向.     

锂离子电池富锂过渡金属氧化物xLi_2MnO_3·(1-x)LiMO_2(M=Ni,Co或Mn)正极材料

作为下一代高比能锂离子电池正极材料的有力竞争者,富锂过渡金属氧化物xLi2MnO3·(1-x)LiMO2(M=Ni,Co或Mn)相对于传统的锂离子电池正极材料而言,具有比容量高的显著优势(可超过300mAh/g),因此近年来得到了广泛关注。本文对富锂过渡金属氧化物xLi2MnO3·(1-x)LiMO2(M=Ni,Co或Mn)近几年的研究进展进行了总结,对该类材料的晶体结构特征以及首次充放电机理、不同合成方法的发展以及电化学性能的改善进行了评述,并对这类材料今后的发展方向提出了思考。     

锂离子电池预锂化补锂策略研究进展

锂离子电池(LIBs)因高能量密度和长循环寿命而被广泛用于储能电子产品、电动汽车等众多领域。然而,在锂离子电池首次充放电过程中,固体电解质界面(SEI)膜的形成会造成电解液发生不可逆分解、初始活性Li⁺损失(ALL)和不可逆容量损失,会影响电池体系容量和能量密度的发挥,对于硅基负极电池体系而言尤为显著。基于这一问题,亟需开发各种补锂策略来降低活性锂损失,有效提高电池体系的首次库仑效率(ICE),从而实现更高的能量密度和循环稳定性。结合现阶段所做工作,从正负极角度出发,将预锂化补锂策略分为正极预锂化和负极预锂化,主要包括富锂正极材料、富锂预锂化试剂、惰性锂金属粉、含锂有机溶液等一系列预锂化补锂措施。通过系统的分类、比较与总结后,对预锂化以实现电池的高能量密度和长循环寿命提出建议,有助于为预锂化策略走向商业化提供启示。     

层状LiMnO_2的溶胶凝胶法合成及其改性

采用溶胶凝胶法合成了锂离子电池正极材料层状锰酸锂(o-L iMnO2),并对其进行了N i2+掺杂改性研究,优化了层状L iMnO2的合成路径及制备条件.采用XRD、充放电实验和交流阻抗测试方法研究了N i2+的掺入对o-L iMnO2充放电容量的影响.结果表明N i2+的掺入明显提高了锰酸锂的放电比容量和循环性能,抑制了循环过程中电池阻抗的增加.     

锂离子电池快充石墨负极研究与应用

相较于传统燃油汽车,电动汽车缓慢的充电速度始终制约了其进一步推广。为电动汽车实现“加油式”快速充电能够缓解充电桩的使用压力,增加电动汽车的应用场景和市场占有率。因此,亟需开发出具有快速充放电能力的高性能锂离子电池。石墨因其低廉的价格和优异的电化学性能已经在锂离子电池负极领域得到了广泛的商业化应用,然而其较低的嵌锂电位导致在快充过程中出现析锂,损害电化学性能的同时会带来安全隐患。因此,必须对石墨进行改良处理,以适应快充技术的需要。本文系统介绍了近年来石墨负极快充化改良领域的研究进展,从成分设计,形貌调控,结构优化,电解液适配等方面进行了评述,并总结了快充石墨面临的挑战,展望了其发展前景,为推动快充技术的商业化应用提供了借鉴。     

锂离子电池快充石墨负极研究与应用

Driven by the excessive environmental pollution caused by the over-use of non-renewable fossil-derived energy, renewable energy and electrochemical energy storage devices have made great progress in the past decades. Electrochemical energy storage devices, such as lithium-ion batteries, have the advantages of high capacity, long life cycle, and good safety performance; therefore, they have been used in various applications. For example, economical and environment-friendly electric vehicles have recently taken up increasing market share. However, when compared with vehicles propelled using fossil-derived energy, the slow charging speed of electric vehicles has always restricted their further promotion. The realization of rapid charging for electric vehicles can alleviate the high-pressure usage of charging piles as well as increase the application and market share of electric vehicles. Therefore, it is important to develop high-performance lithium-ion batteries with rapid charge and discharge capacities. The fast-charging capacity of lithium-ion batteries is limited by the slow migration of lithium ions in the electrode and the electrode/electrolyte interface. Therefore, the key to developing fast-charging lithium-ion batteries lies in the successful design of suitable electrode materials. Because of its low cost and excellent electrochemical performance, graphite has been widely used to develop the cathode of lithium-ion batteries. However, the migration of lithium ions in graphite is slow, resulting in large polarization during the high-current charge and discharge processes. In addition, the low lithium intercalation potential of graphite leads to lithium precipitation during fast charging, which can decrease the electrochemical performance and cause potential safety hazards. Therefore, graphite must be improved to meet the needs of such fast-charging devices. In this article, we systematically introduce the research progress made in recent years within the scope of rapid-charging improvement of graphite(-based) cathodes and then highlight the modification strategies for graphite with the goal of achieving functional coating, desired morphological and structural design, optimized electrolyte properties, and an improved charging protocol. Additionally, this article evaluates the advantages and disadvantages of the modification strategies as well as their application prospects. The scheme of functional coating for modifying graphite must simplify the process and improve production efficiency to meet the needs of industrial development. Morphology design should ensure satisfactory initial Coulomb efficiency, while the improvement of the electrolyte properties and optimization of the charging protocol need to consider the commercialization costs. Finally, this paper proposes further evaluation of the effects of the modification strategies based on soft-pack or cylindrical batteries to strengthen the commercialization prospect of the modification strategies.      

有机硫化合物在锂硫电池中的应用

锂硫电池具有理论能量密度高、环境友好和成本低等优点,有望成为替代锂离子电池的新一代储能系统。然而,锂硫电池充放电产物的绝缘性、可溶性多硫化锂的穿梭效应、硫正极体积膨胀及锂枝晶的不可控生长,严重影响了锂硫电池的实际容量发挥和循环稳定性。为解决上述问题,采用有机硫化合物来替代单质硫作为正极材料是有前途的策略。调控有机硫化合物的硫链、碳链及其相互作用,可改变其电化学反应过程,提高离子/电子电导,抑制穿梭效应。有机硫化合物作为电解液添加剂,可调控硫正极的反应过程并保护金属锂负极,作为聚合物电解质的改性链段可加速锂离子传导。本综述对有机硫化合物在锂硫电池的正极、电解液添加剂和固态电解质中的应用研究进展进行详细的阐述。将有机硫化合物的结构、反应机理和电化学性质联系起来,为解决锂硫电池存在的问题提供见解。最后,提出高性能有机硫化合物的设计合成和机理研究思路,以期实现可实用化的锂硫电池。     

二次电池研究进展

能源的存储和利用是当今科学和技术发展中的重大课题之一,尤其是作为高效的电能/化学能转化装置的二次电池相关技术一直是科学家研究的热点领域。在此背景下,本文较为系统地介绍目前二次电池的重要研究进展,将从二次电池的发展历史引入,再到其相关的基础理论知识的介绍。随后较为详细地讨论当前不同体系的二次电池及相关应的关键材料的研究进展,涉及到锂离子电池、钠离子电池、钾离子电池、镁离子电池、锌离子电池、钙离子电池、铝离子电池、氟离子电池、氯离子电池、双离子电池、锂-硫(硒)电池、钠-硫(硒)电池、钾-硫(硒)电池、多价金属-硫基电池、锂-氧电池、钠-氧电池、钾-氧电池、多价金属-氧气电池、锂-溴(碘)电池、水系金属离子电池、光辅助电池、柔性电池、有机电池、金属-二氧化碳电池等。此外,也介绍了电池研究中常见的电极反应过程表征技术,包括冷冻电镜、透射电镜、同步辐射、原位谱学表征、磁性表征等。本文将有助于研究人员对二次电池进行全面系统的了解与把握,并为之后二次电池的研究提供很好的指导作用。     

锂硫银锗矿固态电解质研究进展

全固态电池因其较高的安全性和能量密度而成为下一代电动汽车和智能电网用储能器件的重点研究方向之一。开发具有高室温锂离子电导率、化学/电化学稳定性优异、对电极材料兼容性优异等特点的固态电解质材料是推动全固态电池发展的重要研究课题之一。硫化物电解质因其相对较高的室温电导率(~10⁻³ S∙cm⁻¹)、较低的电解质/电极固-固界面阻抗等优点而在众多无机固体电解质材料中成为研究热点。本文基于作者多年研究成果和当前国内外发表的相关工作,从电解质的结构、离子传导、合成、综合性能改善及在全固态电池中的应用等方面系统总结了锂硫银锗矿固态电解质材料研究,并分析了该类电解质面临的问题和挑战,最后探讨了其未来可能的研究方向和发展趋势。     

钠离子电池用高性能锑基负极材料的调控策略研究进展

Na-ion batteries (SIBs) are promising alternatives for Li-ion batteries owing to the natural abundance of sodium resources and similar energy storage mechanisms. Although significant progress has been achieved in research on SIBs, there remain several challenges to be addressed. One of the major challenges in the construction of high-performance SIBs is the development of suitable anode materials with a large reversible capacity, high cycling stability, and good rate performance. Alloying anode materials mainly composed of elements from Groups IVA and VA, as well as their alloys, have attracted widespread attention because of their low working voltage, high cost-effectiveness, and large theoretical capacity. Alloying-type anode materials can be alloyed with metallic Na to achieve large reversible capacities, ensuring a high energy density. Antimony is a promising anode material for SIBs owing to its high theoretical specific capacity (660 mAh·g⁻¹, corresponding to the full sodiation Na₃Sb alloy), small degree of electrode polarization (~0.25 V), appropriate Na⁺ deintercalation potential (0.5–0.75 V), low price, and environmental friendliness. However, an important challenge for using Sb-based anode materials is that the high specific capacity is accompanied by large volume changes during cycling. Such changes lead to the pulverization of the active materials and their falling off from the collector, which significantly limit their large-scale application in the field of sodium-ion batteries. Therefore, mitigating the volume expansion issue of Sb-based anode materials in the charge-discharge process is very important for the design of high-performance SIBs. In recent years, researchers have attempted to address this issue by designing special structures to prepare various composites, and substantial progress has been achieved in improving the electrochemical performance of SIBs. In this review, the relationship between the structure and properties of Sb-based materials and their applications in SIBs are presented and discussed in detail. The latest research progress on using Sb-based anode materials for SIBs in redox reaction mechanisms along with their morphology design, structure-performance relationship, etc. have been reviewed. The main objective of this review is to explore the determining factors of the performance of Sb-based anode materials to propose suitable modification strategies for improving their reversible capacity and cycle stability. Finally, future developments, challenges, and prospects of Sb-based anode materials for SIBs are discussed. Despite several challenges, Sb-based materials are very promising anode materials for SIBs with alloying reaction mechanisms. To further improve the large-scale application of Sb-based anode materials, it is necessary to optimize the binder, electrode structure, and electrolyte composition. The combination of in-depth studies on the electrochemical reaction mechanisms and advanced characterization technologies is important for the development and construction of advanced Sb-based anode materials for SIBs. Finally, to achieve extensive large-scale applications, it is necessary to further explore environmentally friendly, low-cost, and controllable synthetic technologies to prepare high-performance Sb-based anode materials. This review provides specific perspectives for the construction and optimization of Sb-based anode materials and suggests scope for future work on Sb-based anode materials, thereby promoting the rapid development and practical application of SIBs.      

Review and prospect of layered lithium nickel manganese oxide as cathode materials for Li-ion batteries

Layered structural lithium metal oxides with rhombohedral α-NaFeO₂ crystal structure have been proven to be particularly suitable for application as cathode materials in lithium-ion batteries. Compared with LiCoO₂, lithium nickel manganese oxides are promising, inexpensive, nontoxic, and have high thermal stability; thus, they are extensively studied as alternative cathode electrode materials to the commercial LiCoO₂ electrode. However, a lot of work needs to be done to reduce cost and extend the effective lifetime. In this paper, the development of the layered lithium nickel manganese oxide cathode materials is reviewed from synthesis method, coating, doping to modification, lithium-rich materials, nanostructured materials, and so on, which can make electrochemical performance better. The prospects of lithium nickel manganese oxides as cathode materials for lithium-ion batteries are also looked forward to.     

镁离子电池正极材料研究进展

镁离子电池(MIBs)因镁资源储量丰富、体积能量密度大、金属镁空气中相对稳定等优势,被认为是具有大规模储能应用潜力的电池体系。然而,镁离子较高的电荷密度和较强的溶剂化作用导致其在正极材料中的可逆脱嵌和固-液界面上的离子扩散相当缓慢,严重影响了MIBs的电化学性能。近年来,人们针对MIBs正极材料开展了大量工作,取得了一定进展,但是还存在不少问题。本文先从MIBs体系的特点出发,阐述其优势和目前所面临的主要挑战,然后从无机正极材料和有机正极材料两方面展开,梳理并总结了各类正极材料的局限性及其解决策略,对优化方法和材料性能间的相关性进行归纳和讨论,为今后进一步发展具有优异电化学性能的MIBs正极材料提供可能的参考。     

锂离子电池氧化亚硅负极结构优化和界面改性研究进展

氧化亚硅(SiO)作为锂离子电池负极材料,具有较高的理论比容量(~2043 mAh·g^-1)以及合适的脱锂电位(< 0.5 V),且原料储量丰富、制备成本较低、对环境友好,被认为是下一代高能量密度锂离子电池负极极具潜力的候选材料。然而,SiO在脱/嵌锂过程中存在着较严重的体积效应(~200%),易导致材料颗粒粉化、脱落,严重影响了SiO负极电极的界面稳定性和电化学性能。近年来,人们围绕SiO负极结构优化和界面改性开展了大量工作。本文先从SiO负极材料的结构特点出发,阐述了该材料面临的主要瓶颈问题;继而从SiO的结构优化、SiO/碳复合和SiO/金属复合等三方面,系统总结了迄今已有的SiO负极结构设计和界面调控策略,并分别对其方法特点、电化学性能以及二者间关联规律进行了比较和归纳,最后对SiO负极材料结构和界面改性的未来发展方向进行了展望。     

水系锌二次电池MnO2正极的晶体结构、反应机理及其改性策略

Because of the advantages of high safety, environment-friendliness, affordability, and ease of processing, aqueous rechargeable zinc batteries (ARZBs) are promising candidates for next-generation large-scale energy storage systems. In recent years, various cathode materials based on vanadium/manganese/cobalt oxides, Prussian blue analogs, and organic compounds have been reported. Among them, manganese dioxide (MnO₂) is widely used in ARZBs due to their outstanding advantages of low toxicity, eco-friendliness, and high capacity (616 mAh∙g⁻¹ based on two-electron transfer). However, the diversity of the crystal structures of MnO₂ and the unpredictability of the electrochemical reaction make it difficult to investigate the specific internal storage mechanism, which impedes further development of the optimal modification strategies. To date, the main recognized energy storage mechanisms are (de)intercalation and dissolution-deposition mechanisms. In the traditional (de)intercalation mechanism, the predominant issues related to MnO₂ during the cycling process include Mn dissolution, irreversible phase transformation, structural collapse, and sluggish ion diffusion kinetics. On the other hand, the detailed reaction path for the dissolution-deposition mechanism, which was developed in recent years, remains controversial. In addition, the incomplete dissolution-deposition of MnO₂ and the highly acidic environment inevitably leads to corrosion and hydrogen evolution of the zinc anode, as well as low Coulombic efficiency. Accordingly, optimization strategies for different reaction mechanisms have been proposed to make zinc-manganese batteries more competitive. For the (de)intercalation mechanism, modification of composite materials and nanostructure optimization strategies can be adopted to inhibit the dissolution of MnO₂ and increase the number of highly active reaction sites, thus enhancing the electrochemical performance. Moreover, the guest pre-intercalation strategy can help optimize the crystal structure of MnO₂, preventing the collapse of the internal structure during cycling. Besides, defect engineering and element doping strategies focus on regulating the distribution of the electronic structure for affecting the properties of MnO₂, resulting in lowering the energy barrier of zinc insertion. For the dissolution-deposition mechanism, the introduction of a neutral acetate and a halide mediator can effectively facilitate the dissolution-deposition of MnO₂. Meanwhile, metal element catalysis can accelerate the reaction kinetics of the MnO₂ dissolution-deposition, so that high-rate performance can be achieved. Furthermore, the decoupling battery system can separate the cathodic and anodic electrolytes to restrain the hydrogen and oxygen evolution reactions and enhance the potential difference. The flow battery system can effectively eliminate the influence of concentration polarization and stabilize the ion concentration in the electrolytes, thus leading to a large capacity (> 100 mAh). Undoubtedly, MnO₂ as a high-capacity, high-voltage cathode material has broad development prospects for ARZBs. Here, we systematically summarize the crystal structures and reaction mechanisms of MnO₂. We also discuss the optimization strategies toward advanced MnO₂ cathode materials for resolving the highlighted issues in zinc-manganese batteries, which are expected to provide research directions for the design and development of high-performance ARZBs.