Isostructural Synthesis of Iron-Based Prussian Blue Analogs for Sodium-Ion Batteries

Rechargeable sodium ion batteries (SIBs) have promising applications in large-scale energy storage systems. Iron-based Prussian blue analogs (PBAs) are considered as potential cathodes owing to their rigid open framework, low-cost, and simple synthesis. However, it is still a challenge to increase the sodium content in the structure of PBAs and thus suppress the generation of defects in the structure. Herein, a series of isostructural PBAs samples are synthesized and the isostructural evolution of PBAs from cubic to monoclinic after modifying the conditions is witnessed. Accompanied by, the increased sodium content and crystallinity are discovered in PBAs structure. The as-obtained sodium iron hexacyanoferrate (Na_1.75Fe[Fe(CN)₆]_0.9743·2.76H₂O) exhibits high charge capacity of 150 mAh g⁻¹ at 0.1 C (17 mA g⁻¹) and excellent rate performance (74 mAh g⁻¹ at 50 C (8500 mA g⁻¹)). Moreover, their highly reversible Na⁺ ions intercalation/de-intercalation mechanism is verified by in situ Raman and Powder X-ray diffraction (PXRD) techniques. More importantly, the Na_1.75Fe[Fe(CN)₆]_0.9743·2.76H₂O sample can be directly assembled in a full cell with hard carbon (HC) anode and shows excellent electrochemical performances. Finally, the relationship between PBAs structure and electrochemical performance is summarized and prospected.     

普鲁士蓝及普鲁士蓝类化合物材料在钠离子电池中的研究进展

近年来,普鲁士蓝(PB)及普鲁士蓝类化合物(PBAs)用于钠离子电池电极材料方面的研究逐渐深入.作为金属有机框架(MOFs)材料,PB及PBAs是具有可调控的化学组成和物理性质的简单配位聚合物.PB及PBAs可直接作为高性能钠离子电池正极材料,也可以通过与其他材料复合用于钠离子电池正极;此外,利用PB及PBAs作为前驱体制备各类具有纳米结构的金属化合物(如金属氧化物、金属硫化物、金属硒化物和金属磷化物等)及金属化合物复合材料,并用于钠离子电池负极.本文简要介绍了PB、PBAs和以它们为前驱体制备的金属化合物及复合材料在钠离子存储方面的应用研究进展.     

钒基普鲁士蓝类似物VHCF用于水系铜电池正极

针对开发高性能水系铜电池电极材料的迫切需求,通过简易的共沉淀法制备钒基普鲁士蓝类似物铁氰化钒(VHCF)用作水系铜电池正极,考察反应温度及转速对VHCF样品表面形貌及微观结构的影响,探究不同VHCF样品在电化学性能上的差异,并分析VHCF样品的铜离子储存机理。研究结果表明：通过适当提升反应温度及搅拌器的转速,可以制备出[Fe(CN)₆]^4-含量多,粒径小且结构稳定的立方相VHCF;丰富的[Fe(CN)₆]^4-可以为Cu²⁺离子提供更多的化学活位点,较小的粒径有利于提高Cu²⁺离子的扩散速率,与普鲁士蓝骨架结合更稳定的结晶水则能改善电池循环稳定性;电化学反应过程中,Cu²⁺离子会取代VHCF骨架中的V⁵⁺离子形成不可逆新相。VHCF正极在0.1 A/g电流密度下的首次放电比容量高达146.5 m A·h/g,循环500次后,保留了56.1 m A·h/g的可逆容量;在1.0 A/g的大电流密度下的放电比容量仍有60...     

水系钠离子电池普鲁士蓝正极材料的制备与电化学性能研究

普鲁士蓝(PB)是一种金属有机骨架配合物, 作为正极材料在水系钠离子电池中有广泛的应用前景。本文采用单一源法制备PB, 系统研究了反应温度、反应时间以及盐酸浓度对PB形貌结构和电化学性能的影响。研究结果表明, 升高反应温度能提高PB结晶性和循环稳定性, 以80 ℃合成的PB为正极材料组装的电池在100圈充放电循环后容量保持率为93.9%。延长反应时间可以使PB粒径增大, 但是反应时间超过6 h后PB粒径基本保持不变。延长反应时间有利于提高循环性能, 10 h所合成PB组装的电池在100圈充放电循环后容量保持率可以达到90%。提高盐酸浓度会改变PB的表面形貌, 同时改善电化学性能。盐酸浓度为0.20 mol/L时, 所得PB组装的电池经过100个循环后, 比容量仍有67.5 mAh/g。本研究可以为制备高性能PB基水系钠离子电池提供理论和实验指导。     

Sodium Stoichiometry Tuning of the Biphasic-NaxMnO2 Cathode for High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are promising alternatives for large-scale energy storage owing to the rich resource and cost effectiveness. However, there are limitations of suitable low-cost, high-rate cathode materials for fast charging and high-power delivery in grid systems. Herein, a biphasic tunnel/layered 0.80Na_0.44MnO₂/0.20Na_0.70MnO₂ (80T/20L) cathode delivering exceptional rate performance through subtly regulating the sodium and manganese stoichiometry is reported. It delivers a reversible capacity of 87 mAh g⁻¹ at 4 A g⁻¹ (33 C), much higher than that of tunnel Na_0.44MnO₂ (72 mAh g⁻¹) and layered Na_0.70MnO₂ (36 mAh g⁻¹). It proves that the one-pot synthesized 80T/20L is able to suppress the deactivation of L-Na_0.70MnO₂ under air-exposure, which improves the specific capacity and cycling stability. Based on electrochemical kinetics analysis, the electrochemical storage of 80T/20L is mainly based on pseudocapacitive surface-controlled process. The thick film of 80T/20L cathode (a single-side mass loading over 10 mg cm⁻²) also has superior properties of pseudocapacitive response (over 83.5% at a low sweep rate of 1 mV s⁻¹) and excellent rate performance. In this sense, the 80T/20L cathode with outstanding comprehensive performance could meet the requirements of high-performance SIBs.     

One-Dimensional Covalent Organic Framework as High-Performance Cathode Materials for Lithium-Ion Batteries

Covalent organic frameworks (COFs) have emerged as a new class of cathode materials for energy storage in recent years. However, they are limited to two-dimensional (2D) or three-dimensional (3D) framework structures. Herein, this work reports designed synthesis of a redox-active one-dimensional (1D) COF and its composites with 1D carbon nanotubes (CNTs) via in situ growth. Used as cathode materials for Li-ion batteries, the 1D COF@CNT composites with unique dendritic core–shell structure can provide abundant and easily accessible redox-active sites, which contribute to improve diffusion rate of lithium ions and the corresponding specific capacity. This synergistic structural design enables excellent electrochemical performance of the cathodes, giving rise to 95% utilization of redox-active sites, high rate capability (81% capacity retention at 10 C), and long cycling stability (86% retention after 600 cycles at 5 C). As the first example to explore the application of 1D COFs in the field of energy storage, this study demonstrates the great potential of this novel type of linear crystalline porous polymers in battery technologies.     

High-Efficiency Cathode Sodium Compensation for Sodium-Ion Batteries

Sodium-ion batteries have gained much attention for their potential application in large-scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the electrochemical performance of sodium-ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high-efficiency cathode sodiation compensation reagent, sodium oxalate (Na₂C₂O₄), which possesses both a high theoretical capacity of 400 mA h g⁻¹ and a capacity utilization as high as 99%, is proposed. The implementation of Na₂C₂O₄ as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2-Na_2/3Ni_1/3Mn_1/3Ti_1/3O₂ cathode with Na₂C₂O₄ as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg⁻¹. This work can provide a new avenue for accelerating the development of SIFCs.     

A Superlattice-Stabilized Layered Oxide Cathode for Sodium-Ion Batteries

Sodium-ion batteries are in high demand for large-scale energy storage applications. Although it is the most prevalent cathode, layered oxide is associated with significant undesirable characteristics, such as multiple plateaus in the charge−discharge profiles, and cation migration during repeated cycling of Na-ions insertion and extraction, which results in sluggish kinetics, capacity loss, and structural deterioration. Here, a new strategy, i.e., the manipulation of transition-metal ordering in layered oxides, is proposed to show a prolonged charge−discharge plateau and cation-migration-free structural evolution. The results demonstrate that the transition-metal ordering with a honeycomb-type superlattice can adjust the crystal lattice and suppress cation migration by modifying the crystal strain to realize a large reversible capacity and excellent cycling performance, which are not characteristics of the widely used common layered oxides. These findings can provide new insight that can be used to improve the design of high-performance electrode materials for secondary-ion batteries.     

A Chemical Precipitation Method Preparing Hollow–Core–Shell Heterostructures Based on the Prussian Blue Analogs as Cathode for Sodium‐Ion Batteries

Prussian blue and its analogs are regarded as the promising cathodes for sodium‐ion batteries (SIBs). Recently, various special structures are constructed to improve the electrochemical properties of these materials. In this study, a novel architecture of Prussian blue analogs with large cavity and multilayer shells is investigated as cathode material for SIBs. Because the hollow structure can relieve volume expansion and core–shell heterostructure can optimize interfacial properties, the complex structure materials exhibited a highly initial capacity of 123 mA h g^?1 and a long cycle life. After 600 cycles, the reversible capacity of the electrode still maintains at 102 mA h g^?1 without significant voltage decay, indicating a superior structure stability and sodium storage kinetics. Even at high current density of 3200 mA g^?1, the electrode still delivers a considerable capacity above 52 mA h g^?1. According to the electrochemical analysis and ex‐situ measurements, it can be inferred that the enhanced apparent diffusion coefficient and improved insertion/extraction performance of electrode have been obtained by building this new morphology.     

磷酸盐系锂离子电池正极材料的研究进展

分别介绍了可以作为锂离子二次电池正极材料的几种磷酸根聚阴离子过渡金属锂盐的研究近况,着重分析了磷酸亚铁锂和磷酸钒锂的现状.LiFePO4为橄榄石结构,具有较高开路电压、高理论容量、电压平台稳定、环境友好等优点,但电子导电率和离子传导率低制约了它的应用,介绍了解决磷酸亚铁锂两低问题的方法;磷酸钒锂为NASCION结构,理论容量比磷酸亚铁锂高,具有一定的研究价值,介绍了磷酸钒锂的制备方法,认为磷酸钒锂最主要的问题是稳定性不高.指出当前锂离子二次电池正极材料应该加快磷酸亚铁锂的工业化进程,加速磷酸钒锂的研究步伐,同时不放松其他更新正极材料的开发.     

Polypyrenes as High‐Performance Cathode Materials for Aluminum Batteries

The pressing need for low‐cost and large‐scale stationary storage of electricity has led to a new wave of research on novel batteries made entirely of components that have high natural abundances and are easy to manufacture. One example of such an anode–electrolyte–cathode architecture comprises metallic aluminum, AlCl₃:[EMIm]Cl (1‐ethyl‐3‐methylimidazolium chloride) ionic liquid and graphite. Various forms of synthetic and natural graphite cathodes have been tested in recent years in this context. Here, a new type of compelling cathode based on inexpensive pyrene polymers is demonstrated. During charging, the condensed aromatic rings of these polymers are oxidized, which is accompanied by the uptake of aluminum tetrachloride anions (AlCl₄^?) from the chloroaluminate ionic liquid. Discharge is the fast inverse process of reduction and the release of AlCl₄^?. The electrochemical properties of the polypyrenes can be fine‐tuned by the appropriate chemical derivatization. This process is showcased here by poly(nitropyrene‐co‐pyrene), which has a storage capacity of 100 mAh g^?1, higher than the neat polypyrene (70 mAh g^?1) or crystalline pyrene (20 mAh g^?1), at a high discharge voltage (≈1.7 V), energy efficiency (≈86%), and cyclic stability (at least 1000 cycles).     

Correction to: Prussian Blue Analogues in Aqueous Batteries and Desalination Batteries

In the published article the authors equal contribution state-ment is incorrect in the foot note. The correct statement should be read as "Chiwei Xu and Zh...     

钠离子电池无粘结剂二氧化钛负极材料的合成

作为电池的重要组成部分,电极材料直接影响电池的能量密度。电极材料在制作过程中往往会添加粘结剂以稳定极片结构,但粘结剂的加入会降低电极材料的比容量,影响其离子迁移速率。通过在经水热反应刻蚀的钛箔/网上原位生长二氧化钛(TiO 2)得到无粘结剂TiO 2/Ti纳米线阵列电极,并系统地研究不同钛基底及水热反应温度对TiO 2/Ti纳米线阵列电极物理性能和电化学性能的影响。结果表明,不同钛基底及水热反应温度均对生长的TiO 2纳米线的形貌和电化学性能有重要影响。其中通过220℃水热反应生长在钛网(0.15 mm)上的TiO 2纳米线呈蛛网状,具有较大的比表面积,属于锐钛矿型TiO 2,储钠过程主要由赝电容效应控制,且具有优秀的电化学性能:首周放电比容量为986 mAh g^-1,库伦效率为21.7%;随后放电比容量逐渐稳定在240 mAh g^-1左右;循环200周后放电比容量仍能达到228 mAh g^-1,库伦效率稳定在99.3%左右;即使在3200 mA g^-1的超大电流密度下,放电比容量仍能达到152 mAh g^-1。无粘结剂电极材料极大可以有限地提升电极材料的比容量,对未来高能量密度电池体系的设计具有一定的理论意义和参考价值。     

Li2MSiO4作锂离子电池正极嵌锂插层的研究进展

对国内外聚阴离子型化合物硅酸盐Li2MSiO4(M=Fe,Mn,Ni,…)正极材料的研究进展进行了综述,着重从材料的制备与结构改性、嵌/脱锂特性、晶型结构等方面进行阐述。最后讨论硅酸盐正极材料所面临的挑战,并指出改善其综合性能的途径。     

用于钠离子正极的锰基普鲁士蓝材料的制备及其性能

钠离子电池由于具有安全、价廉、资源丰富等优点,在大规模储能中具有重要的应用前景.普鲁士蓝类似物具有稳定、开放的框架结构,是非常有前景的正极材料.尽管如此,合成高性能的普鲁士蓝类正极材料仍面临较大挑战,其中之一是普鲁士蓝类似物一般含有较高的结晶水含量,影响材料的电化学性能.通过将极片在高真空下干燥,可有效脱除普鲁士材料中...     

氧化钒作锂离子电池正极材料的研究进展

V_2O_5具有独特的层状结构,适合于锂离子的存储,与传统的锰酸锂、钴酸锂、磷酸铁锂等正极材料相比,具有高的理论比容量、功率密度以及价格低廉、原材料丰富等优势,在作为锂离子电池正极材料方面备受关注。但V_2O_5低的固有电导率及锂离子扩散系数,导致其容量保持率低和倍率性能差;此外,充放电过程中反复的相变会引起结构的不稳定,而且氧化钒会部分溶于电解液,因此表现出差的循环性能。正是由于这些制约因素的存在,对V_2O_5的固有缺陷进行改性研究以提高氧化钒正极材料的电化学性能成为重要的研究热点。将氧化钒进行纳米化以增大比表面积和缩短离子扩散距离,同时通过复合、掺杂改性等方法提高材料的导电性和循环稳定性,从而使V_2O_5正极材料表现出优异的电化学性能成为可能。文章从氧化钒电极材料纳米化,在纳米化的基础上复合导电材料,调节工作电压窗口,掺杂金属离子这四类方法阐述对氧化钒电化学性能的改善,以及各种方法对电极电化学性能的影响。