锂离子电池电解液负极成膜添加剂的研究进展

解决锂离子电池电极材料和电解液相容性的关键是形成稳定且Li⁺可导的固态电解质界面膜(SEI膜),因此,对优质负极成膜添加剂的研究成为锂离子电池研发中的一个热点。本文综述了锂离子电池电解液成膜添加剂的作用原理,具体介绍了各类负极成膜添加剂的研究现状,从成膜反应机理和理论计算方面详述了近几年来负极成膜添加剂的研究进展。分析了所存在的问题主要是如何快速地挑选出更适宜、更高效的成膜添加剂,并指出了成膜添加剂未来的发展趋势为:①研究各添加剂与电解液的反应机理,着重开发对锂离子电池副反应小的负极成膜添加剂;②通过选择两种或两种以上的添加剂的协同作用,以弥补一种添加剂的不足;③提高无机成膜添加剂在电解液中的溶解度。     

锂离子电池电解液SEI成膜添加剂的研究进展

稳定的固体电解质界面（SEI）是提高锂离子电池电化学性能的关键,用电解液添加剂是改善锂离子电池性能最经济有效的方法之一。本文综述了近五年间包括不饱和酯化合物、含硫化合物、锂盐、无机化合物等作为电解液成膜添加剂在锂离子电池中的研究进展和作用机理,对它们的优缺点进行了评价,最后进行了总结和展望。未来成膜类添加剂的研究思路应该为：（1）应以有机物种为主,能够形成弹性模量小的SEI膜,便于适应阳极材料产生的膨胀行为。（2）添加剂要尽量保证形成的SEI膜与石墨等阳极材料产生良好的黏结,因此添加剂形成的聚合物的聚合度不能太小。（3）在没有性能极其优秀的成膜添加剂出现之前,添加剂的分子结构可以在现有的添加剂的基础上进行结构的优化或者官能团的设计。（4）重点攻关当前添加剂的应用的问题,提高添加剂的合成技术,降低合成成本。     

锂离子电池多孔硅基复合负极材料的研究进展

概述了多孔硅基负极材料在锂离子电池中的应用,重点介绍了材料结构和复合方式对其电化学性能的影响;分析了导致其循环性能降低的主要原因,指出控制电池循环过程中硅基材料体积变化、抑制SEI膜的增加是改善硅基负极材料循环性能的重要途径. 对多孔硅基复合负极材料的研究进行了展望,提出在纳米化和复合化的基础上,设计特殊孔道结构、制备多孔的硅/碳复合材料是推进硅基负极材料应用的重要研究方向.     

锂离子电池硅基负极材料研究进展

在高能量密度锂离子电池开发中，应用最关键的是硅基负极材料。而硅基负极的实际应用受到首效低，导电率低，充放电时体积变化很大，造成循环寿命很短的限制。科研人员为此进行了大量的硅基负极材料的改性。本文从硅基负极材料的改性方法、补锂技术、导电剂、粘结剂和电解液添加剂这五个方面的研究进展进行了概述，为硅基负极的商业化应用开发提供了研究方向。     

锂离子电池用硅基负极材料研究进展

硅基负极材料由于出色的储锂容量被认为是最有潜力的锂离子负极材料,但其较差的电导率及脱嵌锂过程中巨大的体积变化导致其循环稳定性较差。本文概述了硅/炭复合负极材料和氧化亚硅复合负极材料的改性方法及研究进展,及其预锂化技术、黏结剂、电解液及添加剂研究等,并对硅基负极的研究现状进行总结及展望。     

铅酸蓄电池电解液添加剂的研究

研究了铅酸蓄电池电解液中加入添加剂对电池性能的影响。通过测定电池放电容量、充电接受能力、极化曲线及荷电保持能力 ,比较了在电解液中加入E、F两种添加剂和不加添加剂的电池性能。结果表明 :在电解液中加入E、F添加剂后 ,电池的充电接受能力尤其是低温充电接受能力得以大大改善 ,并提高了负极析氢过电位 ,从而降低了电池贮存过程中的自放电。     

二氟磷酸锂制备研究进展

二氟磷酸锂是一种在锂离子电池电解液中具有优异性能表现的功能添加剂,可以在锂离子电池的正负极表面形成低阻抗的界面膜,抑制电极与电解液之间的副反应,提高电池的循环寿命。对近年来二氟磷酸锂的合成工艺研究进展进行了回顾,并对各技术方案的特点进行总结。     

锌金属可充电电池研究现状及展望

金属锌凭借高比容量、高丰度、环境友好性和经济性,被认为是一种电池负极材料的理想候选者。然而,锌金属负极本身存在的枝晶、形变、钝化及自腐蚀问题限制了锌金属可充电电池的发展和应用,根源在于锌与水基电解质热力学不稳定。研究表明,锌复合负极、表面处理、三维电极结构以及电解液添加剂和电解液体系探究可以有效缓解上述问题。从锌负极设计和电解液优化2方面整理总结了近年来报导的相关工作,并结合最新提出的新型可逆锌基储能体系,对下一步锌二次电池发展做出展望。     

锂离子电池硅负极粘结材料的研究进展

硅基负极材料因具有较高的理论比容量 4200 mAh/g，已成为国内外新能源锂离子电池负极材料领域研究热点课题。然而，由于硅基材料体积膨胀率高达400%，经多次充放电循环后，硅颗粒会发生破裂和粉化使其在电极基体上易脱落，从而导致电池容量衰减快、寿命短的技术缺陷。为缓解硅颗粒巨大体积变化产生的应力以及维持电极完整性，国内外科学研究者们从电池组成上出发，对活性材料、导电剂、粘结剂、电解液等进行系统研究，其中对聚合物粘结剂改性是一种实现其高寿命、抗衰减的有效手段之一。基于锂离子硅基负极材料优异特性及粘结材料的研究现状，综述了硅基负极组成、结构、性能、作用原理、分子间作用机制以及负极粘结剂的分子结构设计，探讨其对硅基锂离子电池电化学性能的影响规律，为锂离子电池硅基负极粘结材料的应用与开发提供理论和实践指导。     

锂离子电池硅基负极材料的研究进展

硅具有最高的理论比容量、丰富的地壳储量和较低的电压平台，被认为是最有潜力的下一代锂离子电池负极材料，但其在脱嵌锂过程中巨大的体积膨胀及导电性能差都严重影响其性能表现。本文着重聚焦了通过结构设计和复合化这两大方面来改善硅基负极材料性能的一些方案和解决思路，概述了硅基负极材料近年来的研究进展，并对其研究现状进行总结及展望。     

锂离子电池高压电解液研究进展

传统碳酸酯类电解液在高压(>4.3 V, vs. Li/Li+)下易发生氧化分解反应,导致锂离子电池不可逆容量增加、循环性能下降. 为解决这一问题,需从理论和实验两方面对电解液溶剂、锂盐、添加剂及其基本组成等进行针对性设计. 耐高压溶剂是提升电解液稳定性的关键因素之一,既经济又有效,添加高浓锂盐是近年来研究较多的可提升电解液电化学窗口和循环稳定性的新策略. 本工作从耐高压溶剂、高压添加剂和高浓锂盐三方面综述了近几年锂离子电池高压电解液的研究进展.     

从商业化角度看锂-空气电池的发展

锂-空气电池的完全商业化,一直是该研究领域的目标。但实现该目标,必须考虑到各方面的问题,任何小的影响因素都应该尽量考虑在内。负极需要保护其不受水分、二氧化碳、电解液中反应中间物等物质的侵蚀,并抑制枝晶的产生。正极中高效的电极反应催化剂及能容纳放电产物的高比表面积结构是维持电池稳定循环的基本要求。合理的添加剂对电解液性能的提高也非常有必要。电池整体需考虑各种外部因素,如电池构造、尺寸放大等。目前有关锂?空气电池的研究已经取得了很多进展,但仍然缺少决定性突破。以商业化为最终目的,本综述从锂?氧气电池各组成部分切入,对近几年的研究进展进行总结,着重于电池体系整体的研究报道,对未来锂?空气电池的发展进行了展望。     

Additives-containing functional electrolytes for suppressing electrolyte decomposition in lithium-ion batteries

Several olefinic compounds such as vinyl acetate, divinyl adipate and allyl methyl carbonate were studied as additives for propylene carbonate (PC)-based electrolytes in lithium-ion battery, which kind of electrolytes always exfoliate graphitic carbon and decompose drastically to liberate organic gas. Three kinds of graphitic carbons commonly used in lithium-ion batteries, namely, natural graphite, MCMB 6-28 and MCF were chosen to test the decomposition-suppressing ability of additives. The effects of the type of graphitic anodes and the structure of additives on the electrolyte decomposition have been investigated in the terms solid electrolyte interface (SEI) formation, which was characterized by cyclic voltammetry (CV), ac impedance, SEM, XPS analyses, and auger electron spectroscopy (AES). The electrochemical performance of the additives-containing electrolytes in combination with LiCoO₂ cathode and graphitic carbon anode was also tested in coin cells.     

锂离子电池硅负极表面改性的研究进展

硅由于具有高的理论比容量、低的脱嵌锂电位、储量丰富等优势已成为当前高能量密度锂离子电池重要开发的高性能负极材料，但硅负极较大的体膨胀效应和较低的电导率等问题限制硅负极在商业中进一步的应用。针对硅负极材料发展所面临的问题，本文着重从硅的表面改性包括表面包覆、表面功能化、人造固相电解质膜等技术展开综述，分析了这些改性策略及电化学性能改进机理，并对硅表面改性技术进一步发展做了简单展望，旨在开发出高能量密度动力锂电池用关键硅负极材料。     

Recent advances toward high voltage,EC-free electrolytes for graphite-based Li-ion battery

Lithium-ion batteries are a key technology in today’s world and improving their performances requires, in many cases, the use of cathodes operating above the anodic stability of state-of-the-art electrolytes based on ethylene carbonate (EC) mixtures. EC, however, is a crucial component of electrolytes, due to its excellent ability to allow graphite anode operation–also required for high energy density batteries–by stabilizing the electrode/electrolyte interface. In the last years, many alternative electrolytes, aiming at allowing high voltage battery operation, have been proposed. However, often, graphite electrode operation is not well demonstrated in these electrolytes. Thus, we review here the high voltage, EC-free alternative electrolytes, focusing on those allowing the steady operation of graphite anodes. This review covers electrolyte compositions, with the widespread use of additives, the change in main lithium salt, the effect of anion (or Li salt) concentration, but also reports on graphite protection strategies, by coatings or artificial solid electrolyte interphase (SEI) or by use of water-soluble binder for electrode processing as these can also enable the use of graphite in electrolytes with suboptimal intrinsic SEI formation ability.     

界面化学对镍锰酸锂正极材料电化学性能影响的研究现状及分析

尖晶石LiNi_0.5Mn_1.5O₄正极材料因理论比容量和理论比能量高、工作电压高、资源丰富且价格低廉等优点而备受关注,但该材料因为高电压下电解液的分解及界面副反应导致循环性能和倍率性能不佳,制约着材料的推广应用。结合近几年的研究报道,介绍了LiNi_0.5Mn_1.5O₄正极材料的结构及脱嵌机制、表/界面化学、改性方法,着重介绍了LiNi_0.5Mn_1.5O₄材料的表面性质及不同组分之间的界面反应机制及对正极材料电化学性能的影响,指出LiNi_0.5Mn_1.5O₄材料的晶面取向、颗粒形貌、表面元素分布、包覆及离子掺杂是改善镍锰酸锂材料电化学性能的有效途径。同时,通过溶剂替代、成膜添加剂的添加、改变锂盐的种类及浓度等方式,开发与之匹配的耐高压电解液也是提升镍锰酸锂电池性能的重要方法。最后,对LiNi_0.5Mn_1.5O₄正极材料表面改性和电解液界面构筑方面进行了总结和展望,旨在为提升该材料性能的相关研究提供参考。     

Electrochemical and thermal properties of 2,4,6-tris(trifluoromethyl)-1,3,5-triazine as a flame retardant additive in Li-ion batteries

Triazines are well known as flame retardants, however, their properties for battery applications have not been much explored. Flame retardants can play an important role in preventing dangerous situations that may occur when battery packs malfunction or are misused. However, the addition of flame retardants to batteries can degrade their performance due to the non-ionic properties of the additives. In order to overcome this drawback of additives, fluorinated material has been investigated, because fluorination frequently prevents deterioration of performance. A fluoride-rich triazine used as an additive to the electrolyte, 2,4,6-tris(trifluoromethyl)-1,3,5-triazine (TTFMT), showed excellent thermal stability with charged cathodes and anodes. Addition of 5 wt.% TTFMT to the electrolyte reduced the exothermic heat from the oxygen release reaction in the cathode by 54%. Surface film formation on the cathode is discussed with reference to cyclic voltammetry combined with impedance spectroscopy and differential scanning calorimetry. The properties of the film were influenced by the additive so as to markedly reduce the charge-transfer resistance, which enhanced the charge retention during cycle life, the capacity, and the high-rate discharge capacity of the battery.     

Interfacial structural stabilization on amorphous silicon anode for improved cycling performance in lithium-ion batteries

Interfacial structures of electrode-current collector and electrode-electrolyte have been designed to be stabilized for improved cycling performance of amorphous silicon (Si) that is considered as an alternative anode material to graphite for lithium-ion batteries. Interfacial structural stabilization involves the interdigitation of Si electrode-Cu current collector substrate by anodic Cu etching with thiol-induced self-assembly, and the formation of self-assembled siloxane on the surface of Si electrode using silane. The novel interfacial architecture possesses promoted interfacial contact area between Si and Cu, and a surface protective layer of siloxane that suppresses interfacial reactions with the electrolyte of 1 M LiPF₆/ethylene carbonate (EC):diethylene carbondate (DEC). FTIR spectroscopic analyses revealed that a stable solid electrolyte interphase (SEI) layer composed of lithium carbonate, organic compounds with carboxylate metal salt and ester functionalities, and PF-containing species formed when having siloxane on Si electrode. Interfacially stabilized Si electrode exhibited a high capacity retention 80% of the maximum discharge capacity after 200 cycles between 0.1 and 1.5 V vs. Li/Li⁺. The data contribute to a basic understanding of interfacial structural causes responsible for the cycling performance of Si-based alloy anodes in lithium-ion batteries.