Chloromethyl pivalate based electrolyte for non-aqueous lithium oxygen batteries

A novel electrolyte with chloromethyl pivalate(CP) used as solvent was first reported for non-aqueous lithium-oxygen(Li-O_2) batteries. Since there are no α-H atoms in the structure of CP, the CP based electrolyte in both superoxide radical solution and real Li-O_2 battery environment showed good chemical stability against superoxide radicals, which was confirmed by ~1H NMR and ~13C NMR measurements.Without a catalyst in the cathode of Li-O_2 batteries, the batteries showed high specific capacity and cycling stability.     

Organic ionic plastic crystal as electrolyte for lithium-oxygen batteries

Organic ionic plastic crystal composed of 1-ethyl-1-methyl pyrrolidinium bis(fluorosulfonyl)imide (P₁₂FSI) and lithium bis(fluorosulfonyl)imide (LiFSI) was used as electrolyte for lithium-oxygen battery. The battery at room temperature delivered a superior long life (320 cycles) and good rate capability since the electrolyte had good chemical and electrochemical stability, and high ionic conductivity.     

非水溶剂Li-O2电池锂负极研究进展

The aprotic Li-O₂ battery has attracted considerable interest in recent years because of its high theoretical specific energy that is far greater than that achievable with state-of-the-art Li-ion technologies. To date, most Li-O₂ studies, based on a cell configuration with a Li metal anode, aprotic Li⁺ electrolyte and porous O₂ cathode, have focused on O₂ reactions at the cathode. However, these reactions might be complicated by the use of Li metal anode. This is because both the electrolyte and O₂ (from cathode) can react with the Li metal and some parasitic products could cross over to the cathode and interfere with the O₂ reactions occurring therein. In addition, the possibility of dendrite formation on the Li anode, during its multiple plating/stripping cycles, raises serious safety concerns that impede the realization of practical Li-O₂ cells. Therefore, solutions to these issues are urgently needed to achieve a reversible and safety Li anode. This review summarizes recent advances in this field and strategies for achieving high performance Li anode for use in aprotic Li-O₂ batteries. Topics include alternative counter/reference electrodes, electrolytes and additives, composite protection layers and separators, and advanced experimental techniques for studying the Li anode|electrolyte interface. Future developments in relation to Li anode for aprotic Li-O₂ batteries are also discussed.     

Strategies with Functional Materials in Tackling Instability Challenges of Non-aqueous Lithium-Oxygen Batteries

The instabilities of the battery including cathode corrosion/passivation,shuttling effect of the redox mediators,Li anode corrosion,and electrolyte decomposition are major barriers toward the practical implementation of lithium-oxygen(Li-O2)batteries.Functional materials offer great potential in high performance Li-O2 batteries owing to their functional tailorability of chemical modification for alleviating side reactions and improving catalysis activity,well-defined properties for discharge products storage,and fast mass and electron transfer paths.In this review,instability problems of non-aqueous Li-O2 batteries and recent studies related to the functional materials in tackling the instability issues from rational cathode construction,inhibition of redox mediators(RMs)shuttling,anode protection and novel electrolyte design are illustrated.Future research directions to overcome the critical issues are also proposed for this promising battery technology.The instability issues and the related strategies with functional materials based on the comprehensive consideration of all battery components proposed in this review provide the systematic,deep understanding and rational design of functional materials for Li-O2 batteries,which is beneficial to achieving the practical Li-O2 batteries.     

Nature-inspired Three-dimensional Au/Spinach as a Binder-free and Self-standing Cathode for High-performance Li-O2 Batteries

Design and fabrication of functional porous air cathode materials with superior catalytic activity is still the key point for non-aqueous lithium-oxygen(Li-O₂) batteries. Herein, inspired by the self-standing three-dimensional(3D) structure of the natural spinach leaves, a unique binder-free and self-standing porous Au/spinach cathode for high-performance Li-O₂ batteries has been developed. The carbonized spinach leaves serve as a superconductive current collector and an ideal porous host for accommodating catalysts. The Au/spinach cathode could offer enough spaces for accommodating the discharge products, shorten the distance of the oxygen and electrolyte diffusion, and promote the oxygen reduction reaction(ORR) and oxygen evolution reaction (OER) processes. This optimized Au/spinach cathode achieved a high specific area capacity of 7.23 mA‧h/cm² at a current density of 0.05 mA/cm² and exhibited excellent stability(280 cycles at 0.05 mA/cm² with a fixed capacity of 0.2 mA‧h/cm²). The superior performance encourages the construction of more advanced cathode architectures by the use of bio-composites for Li-O₂ batteries.     

Li Ion Exchanged α-MnO2 Nanowires as Efficient Catalysts for Li-O2 Batteries

Due to the limited energy densities, which could be achieved by lithium-ion cells, Li-O₂ batteries, which could provide a promising super energy storage medium, attract much attention nowadays. For its high activity, high storage and low cost, Mn-based oxides have shown versatile application in various batteries. To enhance the cyclability of Li-O₂ batteries, here, we synthesized a kind of α-MnO₂ nanowires as a bifunctional catalyst for Li-O₂ batteries. The particular structure of α-MnO₂ reduces the mass transfer resistance of the battery, and the MnO₂ nanowires were ion exchanged by saturated lithium sulfate solution so as to further improve the performance of the catalyst. The exchanged α-MnO₂ catalyst showed a high discharge specific capacity(6243 mA·h/g at a current density of 200 mA/g) and significantly improved the cyclability up to the 55th cycle(200 mA/g with capacity of 1000 mA·h/g). The results show that the Li ion exchange method is a promising strategy for improving the performance of MnO₂ catalyst for Li-O₂ batteries.     

Hierarchical Porous Carbon Nanotube Spheres for High-performance K-O2 Batteries

In view of the ever-growing pressure for green gas emissionreduction,there is an urgent need for renewable energysystems.Rechargeablealkali metal-oxygen batteries,especially lithium-oxygen(Li-o2)batteries,are deemed themost promising energy storage systems because of their highertheoretical energy density than that of current lithium-ionbatteries[1-5].     

Recent advances in electrocatalysts for non-aqueous Li-O2 batteries

As one of the next-generation energy-storage devices,Li-O₂ battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500 Wh/kg and low cost.However,Li-O₂ battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electro-catalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O₂ batteries which are relatively simpler than other Li-O₂ batteries' structures.Electrocatalysts were summarized including noble metals,nano-carbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiOx storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work.     

硫酸盐功能电解液增强水系钠离子电池NaTi2(PO4)3/C负极材料电化学性能的研究

水系钠离子电池具有钠资源丰富、成本低廉、安全可靠、维护简单等特点,在可再生能源规模储存领域具有重要应用前景。NASICON型NaTi₂(PO₄)₃具有可逆容量高、工作电位低、离子传输快等优点,是目前最受关注的水系钠离子电池负极材料。但是,该材料在传统的水系电解液中结构不稳定,循环性能不足。本论文通过调控Na₂SO₄浓度和引入MgSO₄添加剂,构建了一种新型硫酸盐功能电解液(2 mol·L^-1 Na₂SO₄ + 0.3 mol·L^-1 MgSO₄)。该电解液能够显著增强NaTi₂(PO₄)₃/C材料在充放电循环过程中的结构稳定性,从而提高其电化学可逆性和稳定性。电化学测试表明,NaTi₂(PO₄)₃/C基于该电解液在100 mA·g^-1条件下的可逆容量为93.4 mAh·g^-1,循环100次后容量保持率高达96.5%;基于该电解液构建的Na₂Ni[Fe(CN)₆]|NaTi₂(PO₄)₃/C电池可以稳定循环500次以上。本论文结合XRD、XPS等技术讨论分析了该电解液的功能作用机制,其研究结果为设计低成本高性能水系钠离子电池提供了新思路和实验基础。     

Surface carboxyl groups enhance the capacities of carbonaceous oxygen electrodes for aprotic lithium-oxygen batteries: A direct observation on binder-free electrodes

Carbon cloth was proposed as an ideal model to investigate the effect of surface functional groups. The introduction of surface carboxyl groups significantly enhances the capacities of carbonaceous oxygen diffusion electrodes for the lithium-oxygen batteries.     

无机钠离子电池固体电解质研究进展

地球上钠资源储量丰富、成本低廉,使得钠电池吸引了越来越多研究者的关注。传统的基于有机溶剂电解液体系的钠电池在安全方面存在不足。固态钠离子电池能够有效解决安全的问题,增加电池的安全性能。固态钠离子电池是一种很有前景的储能方式。钠离子固体电解质主要有Na-β-Al_2O_3、钠超离子导体(NASICON)、硫化物、聚合物以及硼氢化物这几类。无机固体电解质相对于聚合物固体电解质,离子电导率有优势。本文总结了三种常见的无机钠离子固体电解质:Na-β-Al_2O_3、NASICON、硫化物的研究进展,从离子电导率和界面稳定性等方面阐述了近年来的发展。     

四丁基六氟磷酸铵作为锂离子电池阻燃添加剂的研究

近年来关于锂离子电池造成的安全问题甚至事故的报道屡见不鲜,锂离子电池的安全问题已经成为人们关注的焦点. 我们用四丁基六氟磷酸铵（TBAPF₆）作为锂离子电池电解液阻燃添加剂,研究发现添加了TBAPF₆的电解液具有明显的阻燃效果,同时电解液电导率下降并不明显. LiCoO₂/Graphite全电池在添加了TBAPF₆的电解液中可逆容量会略有降低,但具有更优异的循环稳定性. 主要是由于TBAPF₆添加量的增加会影响石墨电极的库伦效率,延长活化时间. 通过对LiCoO₂/Graphite全电池绝热加速量热仪（ARC）测试,表明添加TBAPF₆对电池的燃烧有明显的抑制作用. 在TBAPF₆添加量至5%时,电池在300 ^oC内自放热速率不超过0.1^oC/min,电池的安全性显著提高.     

亚磷酸三甲酯作为锂离子电池电解液溶剂的研究

为了提高锂离子电池电解液的热稳定性,使用亚磷酸三甲酯TMP作为溶剂来配置锂离子电池电解液,研究该电解液燃烧性能、电化学性能和热稳定性,并与商业用电解液作了比较.循环性能测试结果表明,亚磷酸三甲酯基电解液与正极材料LiNg0.8Co0.2O2有很好的相容性,有良好的电化学稳定性,而且与PC组成电解液时可一定程度地抑制PC对负极石墨材料的剥离.燃烧试验和微量量热实验表明,TMP的加入能显著地提高电解液的热稳定性与安全性能.     

Al_2O_3包覆对Na_(0.44)MnO_2正极材料高温储钠性能的改善

Na_(0.44)MnO_2具有特殊的三维隧道结构和良好的化学稳定性,是一种理想的钠离子电池正极材料。本文研究了Na_(0.44)MnO_2正极材料的高温电化学性能,采用液相法对Na_(0.44)MnO_2正极材料进行Al_2O_3包覆改性,并通过电化学、形貌分析、结构分析、化学成分表征等方法研究Al_2O_3包覆的改性机制。结果表明:Al_2O_3包覆层有效地隔离了Na_(0.44)MnO_2与电解液的直接接触,缓解了高温下锰的溶解,从而维持了稳定的电极/溶液界面结构。Na_(0.44)MnO_2@Al_2O_3在55°C下的电化学性能相比未包覆Na_(0.44)MnO_2有显著提升:循环100次后容量保持率达79.2%,远高于未包覆的66.5%;在10C (1C=120 mAh·g~(-1))的大电流密度下放电比容量达到63.6 mAh·g~(-1),而未包覆的仅有12.3 mAh·g~(-1)。     

离子液体凝胶聚合物电解质的三元组分相互作用研究

采用Raman光谱、傅里叶转换红外光谱和X-射线衍射光谱研究N-甲基-N-丙基哌啶双三氟甲磺酸亚胺离子液体（PP13TFSI）和双三氟甲磺酸亚胺锂盐（LiTFSI）对PVDF-HFP聚合物聚合方式的影响,结果表明,PP13TFSI、LiTFSI和PVDF-HFP是共混存在的,同时加入PP13TFSI和LiTFSI会使聚合物的聚合方式由晶体结构转变为无定形结构. 通过对电解质及其各组分的线性扫描伏安曲线和热重曲线分析可知,溶剂N-甲基吡咯烷酮（NMP）容易残留在凝胶聚合物电解质（ILGPE）中,这会降低ILGPE的电化学稳定性和热稳定性. 作者对固态LiFePO₄|ILGPE|Li电池的倍率性能进行了研究,实验结果表明其具有较好的倍率性能,当电池倍率由C/10增大至2C,然后再回到C/10时,其容量可以恢复到原来的90.9%左右. 该研究结果对理解PP13TFSI和LiTFSI在ILGPE中的作用机理具有重要的意义.     

氟代碳酸乙烯酯添加剂对钠离子电池正极的影响

使用电解液成膜添加剂是一种简单高效的提高电池循环稳定性的方法。氟代碳酸乙烯酯(FEC)的最低未被占据分子轨道(LUMO)能量较低,易被还原,通常被认为是很好的负极成膜添加剂,但因其最高占据分子轨道(HOMO)能量也较低,抗氧化性较好,故其被认为不在正极上发生作用。本工作结合电化学,形貌分析,化学成分表征,原位结构分析等方法研究了FEC添加剂在钠离子电池中的作用。我们发现适量的FEC添加剂不仅可以显著抑制电解液溶剂碳酸丙烯酯(PC)的分解,而且会在正极上形成一层富NaF的保护层,提高循环过程中正极晶格结构稳定性,从而提高电池的循环稳定性。密度泛函理论(DFT)计算表明,FEC之所以能在正极上形成保护层,可能与其容易在正极界面与钠盐阴离子ClO_4~-结合反应有关。     

“Water-in-salt”聚合物电解质制备及其电化学性能研究

为提高柔性锂离子电池安全性和循环稳定性能,本实验以自由基聚合结合冷冻干燥得到的聚丙烯酰胺膜为电解质载体,引入21 mol·kg^-1 LiTFSI 高浓度电解液,得到“water-in-salt”聚合物电解质。通过聚合物膜的形貌和孔道结构表征,红外光谱分析,离子电导率及电化学稳定窗口测试等对其基本物化特性进行了研究。冷冻干燥得到的聚丙烯酰胺膜内部具有大量微孔结构,有利于电解液的载入。将该吸附了电解液的聚合物电解质膜与锰酸锂(LiMn₂O₄)正极和磷酸钛锂(LiTi₂(PO₄)₃)负极组装全电池进行充放电性能测试。结果表明,制得的柔性聚合物电解质具有良好的拉伸性能,高离子电导率(20°C,4.34 mS·cm^-1)和宽电化学稳定窗口(3.12 V)。以“water-in-salt”聚合物电解质为隔膜组装的LiMn₂O₄||LiTi₂(PO₄)₃ 全电池表现出优异的倍率性能和长循环稳定性。     

Three new bifunctional additive for safer nickel-cobalt-aluminum based lithium ion batteries

The phosphorus-containing additives can help for forming a stable solid electrolyte interface film on the NCA cathode, thus enhance the thermal stability of the electrolyte and cycle performance of the battery.     

PEO基聚合物电解质及其锂硫电池性能研究

锂硫电池由于具有高的理论比能量引起了广泛关注,然而传统液态锂硫电池由于多硫化物的“穿梭效应”以及安全问题而限制了其应用,全固态锂硫电池可显著提高电池安全性能并有望解决多硫化物的穿梭问题. 本文采用传统的溶液浇铸法制备了具有不同的[EO]/[Li⁺]的PEO-LiTFSI聚合物电解质,并将其应用于锂硫电池. 研究发现,虽然[EO]/[Li⁺] = 8的聚合物电解质具有更高的离子电导率,但是[EO]/[Li⁺] = 20的电解质与金属锂负极间的界面阻抗更低,界面稳定性更好. Li|PEO-LiTFSI([EO]/[Li⁺]=20)|Li对称电池在60 °C,电流密度为0.1 mA·cm^-2时可稳定循环超过300 h,而Li|PEO-LiTFSI ([EO]/[Li⁺]=8)|Li对称电池循环75 h就出现了短路现象. 基于PEO-LiTFSI([EO]/[Li⁺]=20)电解质的锂硫电池首圈放电比容量为934 mAh·g^-1,循环16圈后放电比容量为917 mAh·g^-1以上. 而基于PEO-LiTFSI ([EO]/[Li⁺]=8)电解质的锂硫电池,由于与锂负极较低的界面稳定性不能够正常循环,首圈就出现了严重过充现象.     

全固态钠离子电池硫系化合物电解质

全固态钠离子电池具有资源丰富、安全性高等优势,作为未来大规模储能的重要选择而成为近年来先进二次电池前沿研究热点。钠离子硫系化合物电解质室温离子电导率高、弹性模量高、容易冷压成型,能增强电极/电解质界面接触、减小界面阻抗、缓冲电极材料在充放电过程中的应力/应变,是全固态钠离子电池的研究重点。本文对钠离子硫系化合物固态电解质的结构及性质进行了总结,讨论了硫系化合物电解质的本征特性、与电极的界面稳定性,并介绍了硫系化合物全固态钠离子电池的研究现状,最后分析了硫系化合物电解质面临的挑战及今后的发展方向。