Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries(AZIBs)are regarded as promising electrochemical energy storage devices owing to its low cost,intrinsic safety,abundant zinc reserves,and ideal specific capacity.Compared with other cathode materials,manganese dioxide with high voltage,environmental protection,and high theoretical specific capacity receives considerable attention.However,the problems of structural instability,manganese dissolution,and poor electrical conductivity make the exploration of high-performance manganese dioxide still a great challenge and impede its practical applications.Besides,zinc storage mechanisms involved are complex and somewhat controversial.To address these issues,tremendous efforts,such as surface engineering,heteroatoms doping,defect engineering,electrolyte modification,and some advanced characterization technologies,have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism.In this review,we particularly focus on the classification of manganese dioxide based on crystal structures,zinc ions storage mechanisms,the existing challenges,and corresponding optimization strategies as well as structure-performance relationship.In the final section,the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Carbon-coated manganese dioxide nanoparticles and their enhanced electrochemical properties for zinc-ion battery applications

In this study, we report the cost-effective and simple synthesis of carbon-coated α-MnOnanoparticles(α-MnO@C) for use as cathodes of aqueous zinc-ion batteries(ZIBs) for the first time. α-MnO@C was prepared via a gel formation, using maleic acid(CHO) as the carbon source, followed by annealing at low temperature of 270 °C. A uniform carbon network among the α-MnOnanoparticles was observed by transmission electron microscopy. When tested in a zinc cell, the α-MnO@C exhibited a high initial discharge capacity of 272 m Ah/g under 66 m A/g current density compared to 213 m Ah/g, at the same current density, displayed by the pristine sample. Further, α-MnO@C demonstrated superior cycleability compared to the pristine samples. This study may pave the way for the utilizing carbon-coated MnOelectrodes for aqueous ZIB applications and thereby contribute to realizing high performance eco-friendly batteries.

Manganese Dioxide with High Specific Surface Area for Alkaline Battery

The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature. The prepared sample was characterized with X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Brunauer-Emmett-Teller（BET） surface analysis, Fourier transform infrared（FTIR） spectrometry, cyclic voltammetry, alternative current（AC） impedance test and battery discharge test. It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area. The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides（EMD） in Na2SO4 solution, and exhibits larger discharge capacity than EMD, especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

Flexible Zinc-Manganese Dioxide Alkaline Batteries Based on Kelp Electrolytes

Flexible energy-storage devices play a critical role in the development of portable, flexible and wearable electronics. In addition, biological materials including plants or plant-based materials are known for their safety, biodegradability, biocompatibility, environmental benignancy, and low cost. With respect to these advances, a flexible alkaline zinc-manganese dioxide (Zn-MnO2) battery is fabricated with a kelp-based electrolyte in this study. To the best of our knowledge, pure kelp is utilized as a semi-solid electrolyte for flexible Zn-MnO2 alkaline batteries for the first time, with which the as-assembled battery exhibited a specific capacity of 60 mA·h and could discharge for 120 h. Furthermore, the as-assembled Zn-MnO2 battery can be bent into a ring-shape and power a light-emitting diode screen, showing promising potential for the practical application in the future flexible, portable and biodegradable electronic devices.

LR6,LR03 Alkaline Hige Energy Zinc and Manganese Battery

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A Binder-Free Amorphous Manganese Dioxide for Aqueous Zinc-Ion Battery

Aqueous zinc-ion battery has attracted much attention due to its low price, high safety, and high theoretical specific capacity. However, most of their performances are limited by the unsatisfied architecture of cathodes. Herein, we fabricated amorphous manganese dioxide by an in situ deposition method. The amorphous manganese dioxide can directly serve as the cathode of an aqueous zinc-ion battery without a binder. The resultant cathode exhibits a high specific capacity of 133.9 mAh/g at 200 mA/g and a capacity retention of 82% over 50 cycles at 1 A/g.

β-MnO_(2) with proton conversion mechanism in rechargeable zinc ion battery

Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,the under-debate proton reaction mechanism and unsatisfactory electrochemical performance limit their applications.Nanorod b-MnO_(2) synthesized by hydrothermal method is used to investigate the reaction mechanism.As cathode materials for RAZIB,the Zn//b-MnO_(2) delivers 355 mA h g^(-1)(based on cathode mass)at0.1 A g^(-1),and retain 110 mA h g^(-1) after 1000 cycles at 0.2 A g^(-1).Different from conventional zinc ion insertion/extraction mechanism,the proton conversion and Mn ion dissolution/deposition mechanism of b-MnO_(2) is proposed by analyzing the evolution of phase,structure,morphology,and element of b-MnO_(2) electrode,the pH change of electrolyte and the determination of intermediate phase MnO OH.Zinc ion,as a kind of Lewis acid,also provides protons through the formation of ZHS in the proton reaction process.This study of reaction mechanism provides a new perspective for the development of Zn//MnO_(2) battery chemistry.

Effects of current density on preparation of grainy electrolytic manganese dioxide

Grainy electrolytic manganese dioxide was prepared by electrodeposition in a 0.9 mol/L MnSO4 and 2.5 mol/LH2SO4 solution. The structure, particle size and appearance of the grainy electrolytic manganese dioxide were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrographs measurements. Current density has important effects on cell voltage, anodic current efficiency and particle size of the grainy electrolytic manganese dioxide, and the optimum current density is 30 A/dm2. The grainy electrolytic manganese dioxide electrodeposited under the optimum conditions consists of γ-MnO2 with an orthorhombic lattice structure; the grainy electrolytic manganese dioxide has a spherical or sphere-like appearance and a narrow particle size distribution with an average particle diameter of 7.237 μm.

Effects of temperature and concentration of sulfuric acid on the electrodeposition of grainy electrolytic manganese dioxide

The effects of temperature and the concentration of sulfuric acid on the cell voltage, the anode current efficiency of electrodeposition and the particle size of grainy electrolytic manganese dioxide （EMD） were investigated. The structure, particle size and appearance of grainy EMD were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrograph measurements. As the concentration of sulfuric acid increases, both the cell voltage and the average anode current efficiency decrease. With the increase of electrolysis temperature in the range of 30-60℃, the cell voltage, average anode current efficiency and particle size decrease. The optimum temperature of 30℃ and concentration of sulfuric acid of 2.5 mol/L for electrodeposition of the grainy EMD were obtained. XRD patterns show that the grainy EMD electrodeposited under the optimum conditions consists of γ-MnO2 and has an orthorhombic lattice structure. According to the results of SEM, the grainy EMD has a spherical or sphere-like appearance and a narrow particle size distribution with an average size of about 7μm. The grainy EMD is a promising cathode of rechargeable alkaline batteries for high energy density and a prospective precursor for production of the LiMn2O4 cathode of lithium ion batteries.

水系锌离子电池锰基正极材料研究进展

可充电水系锌离子电池由于低成本和高安全性,被认为是储能设备的理想候选者。近年来,锰基正极材料由于低成本、低毒性、高工作电压、价态丰富和晶体结构多变等特点,得到广泛研究。锰基材料在循环过程中因结构坍塌引起的容量衰减,阻碍了水系锌离子电池的进一步发展。综述锰基正极材料的研究进展,包括各种锰基氧化物(MnO_(2)、Mn_(2)O_(3)、Mn_(3)O_(4)和MnO等)及其储锌机理。归纳提高锰基正极材料电化学性能的优化策略,并展望锰基正极材料未来的发展。

锰氧化物正极材料的低温焙烧制备及电化学性能

以电解锰阳极泥(EMAM)为原料,利用焙烧活化法制备了水系锌离子电池(AZIBs)锰氧化物正极材料,通过XRD、TGA、SEM及电化学性能测试考察了氮气氛围下,不同焙烧温度(300、425、575℃)对锰氧化物正极材料的结构、形貌及电化学性能的影响。结果表明,氮气氛围下焙烧提高了锰氧化物正极材料的衍射峰强度和结晶度,材料呈现出片状和颗粒状形态,团聚现象减少,空隙增加;随着焙烧温度的提高,锰氧化物正极材料物相逐渐从α-MnO_(2)转变为Mn_(2)O_(3)与Mn_(3)O_(4);焙烧使锰氧化物正极材料的首次放电比容量、倍率性能和循环性能得到提升,材料具有较小的瓦尔堡系数和更快的Zn^(2+)扩散速度。其中,焙烧温度300℃制备的锰氧化物正极材料(300-EMAM)表现出更好的电化学性能,在5 C倍率下,300-EMAM的初始放电比容量为232 mA·h/g,循环100圈后仍能保持190 mA·h/g的放电比容量;300-EMAM电极具有较低的接触电阻(33.6Ω)和电荷转移电阻(816.3Ω)。

椰壳碳@MnO_(2)纳米材料在水系锌离子电池中的应用

为解决MnO_(2)材料在水系锌离子电池(ZIBs)中存在的导电性差、材料利用率低等问题,以农业废弃物椰壳为原料,将低成本、来源丰富、绿色可再生的生物质资源引入到电极材料中,通过高温碳化得到导电性优异的椰壳碳,用水热法在椰壳碳表面生长MnO_(2)纳米粒子,获得椰壳碳@MnO_(2)复合纳米材料。借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)、电化学技术等表征测试手段,分析该复合材料的形貌结构以及电化学性能。结果表明椰壳碳@MnO_(2)在100 mA g^(-1)的电流密度下,经过300次循环,比容量仍高达到344.6 mA h g^(-1),性能远高于商用MnO_(2)材料(64.3 mA h g^(-1));椰壳碳@MnO_(2)优异的导电性,纳米化的结构设计提高了材料利用率,减少了离子扩散路径,带来更快的离子扩散速率,提高了材料的倍率性能,具有良好的应用前景。

面向锌离子电池的二氧化锰柔性电极制备及电化学性能

二氧化锰(MnO_(2))作为锌离子电池常用的正极材料,在自然界中储量丰富、安全性好、理论容量高,受到研究学者的广泛关注.制备高性能锌离子电池的关键问题之一是构造具有稳定微观结构的阴极.本文选用具有优良导电性的柔性碳布(CC)作为基底,分别使用还原沉积法和电化学沉积法制备了碳布@二氧化锰(CC@MnO_(2))阴极,使用SEM、TEM、XRD、XPS等测试手段对两种工艺条件下得到的电极结构和形貌进行表征分析,探明了电极的微观结构组成.进一步将其组装成扣式锌离子电池,对比研究了不同工艺参数下电池的电化学性能.结果表明,还原沉积法中,使用0.40 mol·L^(-1)KMnO_(4)+0.50 mol·L^(-1)H_(2)SO_(4)的混合溶液制备的电极具备最优的储锌性能(电流密度在0.1 A·g^(-1)时能提供最大为291 m A·h·g^(-1)的放电比容量)、能量密度(293.3 W·h·kg^(-1)和循环稳定性(1 A·g^(-1))电流密度下进行1000次循环后,容量保持率为90.48%,库伦效率为99.87%).此外,通过对电极进行不同充放电状态下的非原位XRD和SEM检测,进一步探索了充放电过程的储能机制.本文深入探讨了基于还原沉积法的CC@MnO_(2)电极优化制备工艺,为高性能锌离子电池的开发提供了重要的参考依据.

锌离子电池锰基正极材料研究进展

可充电水系锌离子电池是一种环保且电化学性能优异的二次电池,但锰基正极材料在充放电过程中结构易坍塌、导电率低、稳定性差等缺点严重制约了水系锌离子电池的发展。笔者首先阐述了锰基正极材料中锌离子的储存机理,主要有Zn^(2+)嵌入/脱出机理、H+/Zn^(2+)共嵌入/脱出机理和化学转化反应机理。Zn^(2+)嵌入/脱出机理包括无相变反应和新相生成反应。而新相生成反应又分为可逆相变和不可逆相变。然后,基于锰基正极材料面临的问题,讨论了改善其储锌性能的主要方法。目前可采用的方法包括缺陷工程、与导电材料复合、离子掺杂、表面修饰技术等。用以上方法改进后的锰基正极材料表现出了更加优异的性能。

锰正极在二次锌锰电池中的研究进展及前景

可充电锌基电池具有成本低、安全性好和比能量高等特点。MnO_(2)及其复合物由于成本低、无毒环保,且具有多晶型、结构可控、高孔隙率等特性,被广泛应用于二次锌锰电池的正极。使用传统碱性电解液的电池,循环寿命短,难以实现多次循环。近年来,含锌离子、锰离子的中性电解液的使用,提高了锌锰电池的可充性能。在介绍二次锌锰电池原理的基础上,阐述碱性电解液和中性电解液体系对电池的影响,对锰正极添加剂、纳米材料的开发、电解液、高导电碳基复合材料应用等方面开展总结和讨论。探讨抑制不可逆相的生成和促进反应向生成可逆相的途径,提出合理的思路,为高性能可充电锌基电池研究提供指导。

二氧化锰作水系锌离子电池正极材料改性进展

二氧化锰以其相对较低的成本和成熟的合成工艺,而成为研究最为深入的锌离子电池(ZIB)正极材料之一。近年来对二氧化锰在ZIB中进行改性的研究报道很多,其主要途径包括表面优化、纳米结构调控、缺陷工程、元素掺杂以及与导电材料的复合。这些改性方法提高了二氧化锰的电化学性能,改善了应用于ZIB正极的循环稳定性、倍率性能,有效延长了电池使用寿命。这些改性为ZIB技术的商业化和实际应用奠定了基础,为可再生能源存储领域的发展提供了有力支持。

聚丙烯酸对LR03型碱锰电池大电流放电性能的影响

采用恒流放电和内阻测试等技术研究聚丙烯酸对LR03型碱锰电池大电流放电性能的影响。结果表明:随着聚丙烯酸量的增加,电池内阻也随之增加,但固液分离现象减少,当聚丙烯酸添加量超过0.35 g/100 g时,锌膏配置完成后24 h无电液析出,放电容量呈先增加后减小的结果。聚丙烯酸与锌粉的最佳质量比为0.35 g/100 g,在聚丙烯酸加入量的实验范围内,600 mA(10 s/m,1 h/d,0.9 V)放电容量的最大值与最小值相差8.26%。

Identification of reversible insertion-type lithium storage reaction of manganese oxide with long cycle lifespan

Recently,MnO2 has gained attention as an electrode material because of its very high theoretical capacity and abundant availability.However,the very high volumetric change caused by its conversion-type reaction results in bad reversibility of charge-discharge.In this study,δ-MnO2 of thickness 8 nm anchored on the surface of carbon nanotubes(CNT)by Mn-O-C chemical bonding is synthesized via a facile hydrothermal method.Numerous ex-situ characterizations of the lithium storage process were performed.Furthermore,density functional theory(DFT)calculations indicated thatδ-MnO2(012)thermodynamically prefers bonding with CNTs.Moreover,the interfacial interaction reinforces the connection of Mn-O and reduces the bond strength of Li-O in lithiated MnO2,which could facilitate an intercalation-type lithium storage reaction.Consequently,the as-synthesizedδ-MnO2 retains an excellent reversible capacity of 577.5 mAh g-1 in 1000 cycles at a high rate of 2 A g-1 between 0.1 V and 3.0 V.The results of this study demonstrate the possibility of employing the cost-effective transition metal oxides as intercalation lithium storage dominant electrodes for advanced rechargeable batteries.

Reductive atmospheric acid leaching of spent alkaline batteries in H_2SO_4/Na_2SO_3 solutions

This work studies the optimum reductive leaching process for manganese and zinc recovery from spent alkaline battery paste. The effects of reducing agents, acid concentration, pulp density, reaction temperature, and leaching time on the dissolution of manganese and zinc were investigated in detail. Manganese dissolution by reductive acidic media is an intermediate-controlled process with an activation energy of 12.28 kJ＇mo1-1. After being leached, manganese and zinc were selectively precipitated with sodium hydroxide. The zinc was entirely con- verted into zincate （Zn（OH）42-） ions and thus did not co-precipitate with manganese hydroxide during this treatment （2.0 M NaOH, 90 min, 200 r/rain, pH 〉 13）. After the manganese was removed from the solution, the Zn（OH）4^2- was precipitated as zinc sulfate in the presence of sulfuric acid. The results indicated that this process could be effective in recovering manganese and zinc from alkaline batteries.

碱性锌-二氧化锰电池三参数测试设备的改进

碱性锌-二氧化锰(碱锰)电池在生产过程中及出厂前要进行相关参数的检验,以保证品质。传统的测试设备和方法在稳定性、误差、速度和精度等方面存在一定问题。对碱锰电池三参数测试设备和测量方法进行改进,以提高稳定性、减少误差。根据具体测量项目进行补偿的取舍:9 V电池负载电压测试时,需加补偿;短路电流测量时,需全面考虑补偿问题。选择电气检测元件时,要考虑元件精度和环境温度等的影响。三参数检测电路的计算误差控制在4‰以内。通过设备设计、安装和调试,检测速度达到0.1 s/组,三参数检测总体精度控制在5‰以内。