Lamellar fiber V2O5·1.6H2O for improving the cyclic performance of aqueous Zn-ion batteries
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摘要:
水系锌离子电池凭借低成本和环境友好的特点具有极大的发展和应用前景. 具有高比表面、分层、或快速离子导体结构的钒基材料是锌离子电池最具有前景的正极材料之一. 如何改善钒基材料的长循环性能是亟待解决的问题之一. 本文采用溶胶凝胶法并冷冻干燥成功制备了V2O5·1.6H2O干凝胶,利用X射线衍射仪、扫描电子显微镜对其物相和形貌进行了表征,发现制备的材料为V2O5·1.6H2O,结晶相良好,且成片状纤维大孔结构. 电化学测试表明,在0.1 A·g–1电流密度下,首次放电比容量为388.4 mA·h·g–1,循环1000次后容量仍保持为129.7 mA·h·g–1,具有良好的长循环稳定性. 在0.1、0.2、0.5、1、2和3 A·g-1电流密度下,纤维状V2O5干凝胶表现出良好的倍率性能,放电比容量分别为388.4、338.5、282.9、239.1、194.4和165.9 mA·h·g–1,远高于商业化V2O5 (279.5、251.0、205.5、174.5、144.6和125.1 mA·h·g–1). 良好的电化学性能主要归功于结合水的支撑作用增大了层间距,在循环过程中材料具有良好的结构稳定性,避免了放电容量衰减;同时纤维片状结构缩短了锌离子的迁移路径. 对充放电机理研究发现,在锌离子的嵌入脱出过程中伴随有碱式硫酸锌的生成与消失,且该过程可逆.
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关键词:
- 锌离子电池 /
- V2O5·1.6H2O /
- 正极材料 /
- 长循环性能 /
- 机理探究
Abstract:Aqueous zinc-ion batteries have great development and application prospects due to the low cost and environmental friendliness. Vanadium-based materials with high specific surface area and layered or fast ionic conductor structures are among the most promising cathode materials for zinc-ion batteries. Layered vanadium pentoxide cathodes have higher capacity and adjustable interlayer spacing, which have been extensively examined. As a layered vanadium pentoxide, V2O5·nH2O is widely evaluated because of its high theoretical capacity, simple synthesis process, etc. However, the practical application of layered V2O5·nH2O is still hindered by structural collapse during cycling and slow Zn2+ diffusion in the V2O5·nH2O cathode. How to improve the long-cycle performance of V2O5·nH2O remains to be solved. In this study, V2O5·1.6H2O xerogel was successfully prepared by the sol-gel method combined with the freeze-drying technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the phase composition and morphology. The results showed that the prepared material was primarily V2O5·1.6H2O with good crystallinity, and little V2O5 still existed. V2O5·1.6H2O grew like macroporous lamellar fibers of approximately 100 nm thick. Compared with commercialized V2O5, V2O5·1.6H2O has larger interlayer space, which benefits the diffusion of Zn2+, and the crystal H2O may help stabilize the structure. Electrochemical performance results revealed that the fibrous V2O5·1.6H2O cathode material showed an initial discharge capacity of 388.4 mA·h·g–1 at a constant current of 0.1 A·g–1 and it still maintained at 129.7 mA·h·g−1 after 1000 cycles, with nearly no capacity decay. At 0.1, 0.2, 0.5, 1, 2, and 3 A·g−1, the fibrous V2O5·1.6H2O xerogel show capacities of 388.4, 338.5, 282.9, 239.1, 194.4, and 165.9 mA·h·g−1, respectively. The capacity was much higher than that of commercialized V2O5, which only showed 279.5, 251.0, 205.5, 174.5, 144.6, and 125.1 mA·h·g−1, respectively, at the same discharge current density. The good electrochemical performance was mainly attributed to the large layer spacing, combined with the supporting effect of H2O, which contributed to the good structural stability of the material during the cycle and avoided the degradation of material properties. In addition, the fibrous structure shortened the Zn2+ diffusion path and increased the electronic conductivity also contributed to the enhanced electrochemical performance. The mechanism of the charge and discharge process was examined by ex-situ X-ray photoelectron spectroscopy (XPS) and XRD. The results showed that the formation and disappearance of basic zinc sulfate are accompanied by the embedding and removal of zinc ions, and the process is reversible.
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Keywords:
- Zn-ion battery /
- V2O5·1.6H2O /
- cathode material /
- cyclic performance /
- mechanism exploration
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随着经济全球化快速发展、电子电力设备的大规模应用,人们对储能器件提出了更高要求. 近年来,锂离子电池被广泛应用,但其制造和使用成本高、锂金属存储量低、有机电解液容易污染环境等问题已不能满足人们的需求[1−2]. 寻找合适的可替代电池已成为当下研究的热点. 锌金属在地壳中储量丰富、价格低廉,而水系电解液导电能力强、成本低、对环境污染小、安全稳定、制备方法简单、成本更低,有利于提高能量密度,因此水系锌离子电池具有广阔的发展和应用前景.
目前水系锌离子电池正极材料主要有锰基、钒基、普鲁士蓝及具有大层间距、快速传输通道的部分过渡金属氧化物等[3−5]. 其中,钒基材料价格低廉、储量丰富且理论容量高具有广阔的研究前景. 目前,钒基材料主要有钒的氧化物、硫化物、钒酸盐和钒的磷酸盐[6−8]. V2O5具有类金字塔形的分层堆叠结构,共享边缘和角,是理想的Zn2+宿主材料之一,其理论容量为589 mA·h·g–1. 然而循环过程中的巨大体积变化导致其循环稳定性较差[9−11]. 针对此缺点,已开发了阳离子/分子插层、结构设计、构筑复合材料等方法. 在离子/分子插层改性方面,Nazar等[12]首次将单层水分子嵌入五氧化二钒层间,获得了良好的电化学性能. 麦立强等[13]进一步证实了结构水在Zn2+插入过程中起着关键作用. 此外,采用NH4+[14]、Li+[15]及过渡金属离子(Fe2+、Co2+、Ni2+、Mn2+、Zn2+、Cu2+等)[16]插层也可以提高V2O5的稳定性. 在结构设计方面,纳米纤维[17]、纳米片[18]、空心球[19]等具有特殊形貌的V2O5独特的微观结构为Zn2+的嵌入/脱出提供了开放通道,缩短了扩散路径,大大缩短了Zn2+的扩散距离[20]. 此外,将V2O5与导电聚合物聚苯胺[21]、碳纳米管(CNT)[22]等复合也取得了一定成效,改善了正极材料溶解现象.
本文采用溶胶凝胶法制备了一种纤维状介孔V2O5·1.6H2O干凝胶,并将其用作锌离子电池的正极材料,其特殊的形貌结构与结合水的支撑作用共同提升了电池的循环性能,并对其进行了电化学动力学和机理探究.
1. 实验部分
1.1 样品制备
1.1.1 V2O5干凝胶制备
将0.3000 g V2O5粉末(纯度>99.4%)(C-V2O5)加入4.65 mL去离子水和4.65 mL H2O2,搅拌15 min后超声15 min (40 kHz),陈化12 h后中加入30 mL去离子水,继续超声直至物质分散均匀. 将所得溶液冷冻干燥36 h,然后放入鼓风烘箱60 ℃干燥3 h,即得到五氧化二钒干凝胶(G-V2O5).
1.1.2 电极制备
将活性物质、乙炔黑、聚偏氟乙烯(PVDF)以质量比为7∶2∶1与质量分数30%的甲基吡咯烷酮(NMP)混合均匀后形成浆料,然后将浆料均匀地涂覆在不锈钢网上,置于真空烘箱中60 ℃干燥12 h,然后用压片机冲制为直径1.3 cm的电极片. 以所制备电极片为正极,锌箔作为负极,玻璃纤维作为隔膜,3 mol·L–1 ZnSO4为电解液组装成CR2032型纽扣电池并静置8 h.
1.2 测试与表征
X射线衍射仪(XRD,BRUKER,5°~80°,Cu Kα射线,40 kV,100 mA)对材料进行物相表征,冷场扫描电子显微镜(SEM,日本HITACHI公司,加速电压:0~40 kV)、 X射线光电子能谱仪(XPS,赛默飞世尔科技公司,Al Kα射线,电压12 kV,电流6 mA)对材料进行形貌及表面分析表征,Autolab电化学工作站(瑞士万通)对材料进行循环伏安测试(CV,电压窗口0.4~1.6 V,扫描速度0.1~1.0 mV·s–1)和交流阻抗测试(EIS,0.1~105 Hz,±10 mV),蓝电电池测试系统(武汉市蓝电电子股份有限公司,电压窗口为0.4~1.6 V)对材料进行恒流充放电测试及倍率性能测试.
不同充放电状态的电极片:将循环截止到一定电压的电极片取出,用电解液淋洗,并用吸水纸从极片侧面吸掉表面溶液后,于手套箱过渡仓进行抽真空干燥,然后进行XPS、XRD、SEM测试.
2. 结果与讨论
2.1 V2O5·1.6H2O干凝胶制备机理及其微观结构表征
在制备过程中,先将V2O5粉末与去离子水放入同一烧杯中并超声混合均匀,再加入H2O2溶液,之后会发生剧烈的放热反应,释放大量的O2,5 min后变成具有一定粘度的红棕色粘性凝胶. 相应的反应:
$$ {\mathrm{V}}_{2}{\mathrm{O}}_{5} + 2 {\mathrm{H}}_{2}{\mathrm{O}}_{2} \rightleftharpoons 2 {\mathrm{HVO}}_{4} + {\mathrm{H}}_{2}{\mathrm{O}} $$ $$ 2 {\mathrm{HVO}}_{4} + (n–1) {\mathrm{H}}_{2}{\mathrm{O}} \rightleftharpoons {\mathrm{V}}_{2}{\mathrm{O}}_{5}\cdot n{\mathrm{H}}_{2}{\mathrm{O}} + {\mathrm{O}}_{2} $$ 图1为C-V2O5和G-V2O5的XRD图,插图分别为对应的晶体结构图. 从图中可以发现,C-V2O5与G-V2O5均与标准比对卡的衍射峰一一对应,且C-V2O5物相很纯,制备的样品G-V2O5主要以V2O5·1.6H2O存在,7.49°和23.09°处的明显的衍射峰分别对应V2O5·1.6H2O的(001)和(003)衍射晶面,同时存在少量的V2O5. 晶体结构图显示V2O5·1.6H2O层间距大于不含结晶水的V2O5,有利于Zn2+的脱嵌,这可能是结晶水存在导致的.
微观形貌分析显示,C-V2O5为大小不一的块状结构,大颗粒尺寸约为1.5 μm,小颗粒尺寸约为200 nm;G-V2O5为相互交织的片层多孔纤维状,片层纤维直径约500 nm,厚度约100 nm. 能谱分析表明G-V2O5中V和O具有均匀的分布,如图2所示.
2.2 电化学性能表征
从前3圈的循环伏安(CV)曲线可以看到,在第1圈循环中C-V2O5有2个明显的氧化峰(1.21和1.03 V)、一个明显的还原峰(1.00 V)和一个较弱的还原峰(0.54 V). 随着反应的进行,峰面积逐渐增大,氧化峰和还原峰逐渐增强,在第3圈时出现明显的3组氧化峰及还原峰,说明充放电过程中C-V2O5逐渐被活化,如图3(a). 而G-V2O5则表现出相对稳定的电化学过程,前3圈分别有较宽的两组氧化峰(0.74和1.15 V)和还原峰(0.54 和0.91 V),曲线重合性良好,说明G-V2O5可逆性较好,如图3(b). 图3(c)为C-V2O5和G-V2O5在0.1 A·g–1时的充放电曲线,可以看出C-V2O5在0.74、1.03和1.21 V有三个充电平台,而在1.16 V左右具有不太明显的一个小放电平台,在0.91和0.54 V有较明显的放电平台,这分别对应于CV中的氧化还原峰,放电比容量为265.8 mA·h·g–1;而G-V2O5明显的充放电平台分别位于0.74、1.15 V和0.54、0.91 V,与CV结果一致,放电比容量为418.5 mA·h·g–1. 此外,在相同扫描速度0.1 mV·s–1下,G-V2O5具有较大的电流,其积分面积大于C-V2O5,说明该材料的放电比容量高于C-V2O5,这与恒流充放电曲线是一致的.
图4(a)为C-V2O5和G-V2O5在电流密度1 A·g–1时的循环性能. 由于C-V2O5是尺寸较大的块体颗粒,其活化过程相对较长,前150圈循环过程中容量逐渐增加. 随着循环次数的增加,C-V2O5结构出现了坍塌,容量逐渐下降,300次循环后逐渐趋于稳定,1000次循环后容量为70.5 mA·h·g–1. G-V2O5经1000次循环后,容量保持在129.7 mA·h·g–1,这可能是由于G-V2O5中结晶水对V2O5结构的支撑作用,稳定的结构为Zn2+ 快速插层提供了宽敞的通道. 还可能是溶剂化的水分子在循环过程中产生了电荷屏蔽作用,Zn2+在水溶液中的有效电荷大大减少,与V2O5骨架的静电相互作用减弱,有效地促进了锌离子的扩散. 此外,片层纤维的形貌与大块体颗粒相比,具有较大的反应接触面积,使得材料避免了前期的活化过程,同时薄片层缩短了离子和电子的传输路径,有利于充放电过程中离子和电子的迁移.
两种材料的倍率性能测试结果如图4(b)所示,在0.1、0.2、0.5、1、2和3 A·g–1电流密度下,C-V2O5放电比容量分别为279.5、251.0、205.5、174.5、144.6和125.1 mA·h·g–1,G-V2O5放电比容量分别为388.4、338.5、282.9、239.1、194.4和165.9 mA·h·g–1. G-V2O5在放电倍率下均具有相对较高的放电比容量,且G-V2O5在1、2和3 A·g–1较大电流密度下具有接近的放电比容量,说明G-V2O5具有良好的倍率性能且具备快速充放电的潜质. 同时在循环60圈后再次以0.1 A·g–1放电时,放电比容量仍维持在212.7和310.1 mA·h·g–1,表明两种材料均具有良好恢复性,且G-V2O5的性能更优.
图5(a)为C-V2O5与G-V2O5未经循环的电化学交流阻抗谱(EIS)谱图,插图为区间放大图和对应的拟合电路图. Rs表示溶液电阻,CPE表示双电层构成的电容,Rct表示电荷转移时造成的电阻,Zw即由扩散控制的Warburg阻抗. 阻抗的Nyquist曲线在高频区和低频区分别出现一个半圆和一条曲线,在高频区电池主要受到电荷转移电阻的影响,而在低频区则为典型的Warburg阻抗控制关[23−24]. 由于没有电化学活化,二者均表现出相对较大的电荷转移电阻. 相比较而言,G-V2O5显示出更小的半圆弧直径,经拟合Rct为275 Ω,远小于C-V2O5的Rct值(679 Ω),说明相同组装、测试条件下,G-V2O5电荷转移阻抗更小. 图5(b)为G-V2O5循环前三圈的EIS图. 经过循环后,G-V2O5的电化学过程仍然受高频区的电荷转移电阻和低频区的Warburg阻抗控制. 由于电化学活化的作用,电解液与活性材料有了充分的接触,使得随着循环次数的增加,电荷转移电阻未发生明显变化,预示着稳定的电化学性能,这与充放电测试、循环伏安测试结果相一致.
2.3 电化学动力学
为了进一步探究G-V2O5电化学动力学过程,在不同扫描速率下进行了CV测试,图6(a)所示. CV曲线显示相似的形状,随着扫描速率的增加,峰逐渐变宽,同时其表现出的氧化峰右移,还原峰左移,表明明G-V2O5的电化学过程是受动力学控制的. 通过式(1)和(2)来描述特定电位下的电流(i)和扫描速率(v)之间的关系[25−26]:
$$ {{i}} = {{a}}{{{v}}^{{b}}} $$ (1) $$ \text{lg}i=b\times \mathrm{lg}v+\mathrm{lg}a $$ (2) 式中,a和b表示可调参数,通常系数b在0.5~1.0之间,b值为0.5表示扩散限制控制过程,1.0表示电容过程控制. 对数电流lgi与对数扫描速率lgv之间的线性关系如图6(b)所示,由四个氧化还原峰的斜率确定的b值分别为0.5、0.59、0.76、0.63,这意味着G-V2O5的电化学过程既有离子扩散控制过程也包含赝电容效应. 赝电容效应的存在使得材料具有快速充放电的特性.
根据式(3)和(4)进一步计算G-V2O5电极在不同扫描速率下的赝电容所占贡献比例[27−28],如图7所示.
$$ {{i}} = {{{k}}_1}{{v}} + {{{k}}_2}{{{v}}^{_{1/2 }}} $$ (3) $$ {{i/}}{{{v}}^{{{1/2}}}} = {{{k}}_{{1}}}{{{v}}^{{{1/2}}}} + {{{k}}_{{2}}} $$ (4) 式中,k1v和k2v1/2分别表示赝电容贡献和扩散控制贡献. 通过计算发现,扫描速率为0.2、0.4、0.6、0.8和1 mV·s–1时,赝电容贡献分别占到了41.4%、48.7%、53.8%、57.9%和61.1%. 扫描速率越快,赝电容贡献越大. 由于赝电容的贡献使得G-V2O5在较大放电电流密度下具有良好的电化学性能,该结果与倍率性能测试结果吻合.
2.4 机理探究
为了探究G-V2O5的电化学反应机理,对G-V2O5的充放电过程进行了非原位的XPS和XRD测试. 图8为G-V2O5在不同充放电状态下Zn 2p 和V 2p的非原位XPS谱图. 初始态时,并没有观察到有Zn 2p的谱峰,说明原材料中没有Zn元素;当放电到0.4 V,由于Zn2+的嵌入,此时在1022.5和1045.6 eV出现了较强的Zn 2p3/2和Zn 2p1/2谱峰;当充电到1.6 V时,仍能观察到Zn 2p3/2和Zn 2p1/2谱峰,但峰强度较弱,说明此时Zn2+并未完全脱出. 与之相对应,在初始状态时,位于517.3和524.8 eV处的峰归属于V5+ 2p3/2和V5+ 2p1/2,516.0和523.0 eV处的谱峰归属于V4+ 2p3/2和V4+ 2p1/2[29],但V4+谱峰的积分面积远小于V5+谱峰的积分面积,同时在XRD中(图1)并未发现V4+氧化物及其他复合物的存在,说明V4+的含量很低;当放电到0.4 V后,V5+谱峰的积分面积远小于V4+谱峰的积分面积,说明由于锌离子嵌入,V5+几乎全部被还原成V4+,仅有少量V5+存在;充电到1.6 V时,V4+谱峰积分面积较小,V5+谱峰积分面积较大,说明此时锌离子并未完全脱出,仍有少量V4+存在.
图9为G-V2O5在不同放电电压(1.6、1.0、0.7、0.4 V)和充电电压(0.8、1.1、1.6 V)状态下的XRD图. 可见,6.80°处V2O5·1.6H2O的衍射峰随着放电的进行,衍射峰强度逐渐减弱,放电到0.4 V时已消失;随着充电过程的进行,该衍射峰逐渐出现且强度逐渐增加,在充电到1.6 V时强度达到最大,说明在充放电过程中伴随有Zn2+的嵌入/脱出过程. 此外,8.52°、14.95°、17.08°、25.83°、27.45°、28.64°、32.72°、33.82°和37.14°的衍射峰也发生了一定的变化,随着放电过程的进行,这几处的衍射峰从无到有,且在放电到0.4 V时衍射强度最大;随着充电过程的进行,该衍射峰逐渐消失,经物相匹配发现,衍射峰与碱式硫酸锌(Zn4SO4(OH)6∙4H2O,JCPDS No. 44-0673)匹配良好,说明在锌离子嵌入脱出过程中形成了碱式硫酸锌,且该过程可逆性良好. 该过程的化学反应方程式如下:
图 9 (a) G-V2O5在0.5 A·g–1时的充放电曲线图,图中☆号标记为测试结构分析所选位置,(b) G-V2O5电极充放电过程中的XRD图.Figure 9. (a) Galvanostatic charge/discharge curves at 0.5 A·g–1, where ☆ marks the states that patterns are collected for structural analysis, and (b) XRD patterns of the G-V2O5 electrode at different charge/discharge states.$$ {\mathrm{V}}_{2}{\mathrm{O}}_{5}\cdot1.6{\mathrm{H}}_{2}{\mathrm{O}} + x{\mathrm{Zn}}^{2+} + 2x{\mathrm{e}}^{–} \rightleftharpoons{\mathrm{Zn}}_{x}{\mathrm{V}}_{2}{\mathrm{O}}_{5}\cdot1.6{\mathrm{H}}_{2}{\mathrm{O}} $$ $$ 4{\mathrm{Zn}}^{2+} + {\mathrm{SO}}_{4}^{2–}+ 4{\mathrm{H}}_{2}{\mathrm{O}} +6{\mathrm{OH}}^{–} \rightleftharpoons {\mathrm{Zn}}_{4}{\mathrm{SO}}_{4}({\mathrm{OH}})_{6}\cdot4{\mathrm{H}}_{2}{\mathrm{O}} $$ 对G-V2O5不同状态的电极片进行表征(图10)发现,初始状态的材料中,大片状的纤维结构被破坏,仅能观察到较小的片层纤维结构,纤维片层与导电剂、粘结剂混合均匀. 放电到1.6 V与充电到1.6 V所对应状态的材料形貌并未有大的变化,说明了材料具有良好的可逆性. 然而在放电到0.4 V时,样品中出现了棱角分明的薄片,薄片厚度仅为40 nm,这可能是碱式硫酸锌,该结果与文献报道一致[30].
3. 结论
(1) 本文成功制备了片层纤维状五氧化二钒干凝胶G-V2O5,将其作为水系锌离子电池正极材料,表现出比商业化V2O5更优异的循环稳定性和倍率性能,这主要源于结合水的存在使得V2O5具有较大的层间距和良好的结构稳定性,特殊的片层纤维结构使得材料具有良好的电子和离子导电性.
(2) G-V2O5电极材料在电流密度0.1 A·g–1时,初始放电比容量为388.4 mA·h·g–1,循环1000次后,放电比容量维持在129.7 mA·h·g–1,显示出优异的循环稳定性.
(3) 电化学机理研究表明,电极反应过程中存在离子扩散控制和赝电容效应,随着电流密度的增加,赝电容贡献逐渐增加,使得该材料具有快速充放电的特性.
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图 9 (a) G-V2O5在0.5 A·g–1时的充放电曲线图,图中☆号标记为测试结构分析所选位置,(b) G-V2O5电极充放电过程中的XRD图.
Figure 9. (a) Galvanostatic charge/discharge curves at 0.5 A·g–1, where ☆ marks the states that patterns are collected for structural analysis, and (b) XRD patterns of the G-V2O5 electrode at different charge/discharge states.
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[1] Gao Y X, Liu Z X, Guo S, et al. Fundamental understanding and effect of anionic chemistry in zinc batteries. Energy Environ Mater, 2022, 5(1): 186 doi: 10.1002/eem2.12225
[2] Wang Z Q, Zhou M, Qin L P, et al. Simultaneous regulation of cations and anions in an electrolyte for high-capacity, high-stability aqueous zinc-vanadium batteries. eScience, 2022, 2(2): 209 doi: 10.1016/j.esci.2022.03.002
[3] Zhang Z C, Li W, Shen Y, et al. Issues and opportunities of manganese-based materials for enhanced Zn-ion storage performances. J Energy Storage, 2022, 45: 103729 doi: 10.1016/j.est.2021.103729
[4] Zeng Y X, Xu J Z, Wang Y, et al. Formation of CuMn Prussian blue analog double-shelled nanoboxes toward long-life Zn-ion batteries. Angew Chem Int Ed, 2022, 61(48): e202212031 doi: 10.1002/anie.202212031
[5] Guo C, Yi S J, Si R, et al. Advances on defect engineering of vanadium-based compounds for high-energy aqueous zinc-ion batteries. Adv Energy Mater, 2022, 12(40): 2202039 doi: 10.1002/aenm.202202039
[6] Wan F, Niu Z Q. Design strategies for vanadium-based aqueous zinc-ion batteries. Angew Chem Int Ed, 2019, 58(46): 16358 doi: 10.1002/anie.201903941
[7] Luo Z X, Zeng J, Liu Z, et al. Carbon-coated hydrated vanadium dioxide for high-performance aqueous zinc-ion batteries. J Alloys Compd, 2022, 906: 164388 doi: 10.1016/j.jallcom.2022.164388
[8] Liu N, Li B, He Z X, et al. Recent advances and perspectives on vanadium- and manganese-based cathode materials for aqueous zinc ion batteries. J Energy Chem, 2021, 59: 134 doi: 10.1016/j.jechem.2020.10.044
[9] Pang Q, He W, Yu X Y, et al. Aluminium pre-intercalated orthorhombic V2O5 as high-performance cathode material for aqueous zinc-ion batteries. Appl Surf Sci, 2021, 538: 148043 doi: 10.1016/j.apsusc.2020.148043
[10] Jia X X, Liu C F, Neale Z G, et al. Active materials for aqueous zinc ion batteries: Synthesis, crystal structure, morphology, and electrochemistry. Chem Rev, 2020, 120(15): 7795 doi: 10.1021/acs.chemrev.9b00628
[11] Hao Y, Zhang S M, Tao P, et al. Pillaring effect of K ion anchoring for stable V2O5-based zinc-ion battery cathodes. ChemNanoMat, 2020, 6(5): 797 doi: 10.1002/cnma.202000105
[12] Kundu D P, Adams B D, Duffort V, et al. A high-capacity and long-life aqueous rechargeable zinc battery using a metal oxide intercalation cathode. Nat Energy, 2016, 1(10): 16119 doi: 10.1038/nenergy.2016.119
[13] Yan M Y, He P, Chen Y, et al. Water-lubricated intercalation in V2O5· nH2O for high-capacity and high-rate aqueous rechargeable zinc batteries. Adv Mater, 2018, 30(1): 1703725 doi: 10.1002/adma.201703725
[14] Zhao H N, Fu Q, Yang D, et al. In operando synchrotron studies of NH4+ preintercalated V2O5· nH2O nanobelts as the cathode material for aqueous rechargeable zinc batteries. ACS Nano, 2020, 14(9): 11809 doi: 10.1021/acsnano.0c04669
[15] Yang Y Q, Tang Y, Fang G Z, et al. Li+ intercalated V2O5· nH2O with enlarged layer spacing and fast ion diffusion as an aqueous zinc-ion battery cathode. Energy Environ Sci, 2018, 11(11): 3157 doi: 10.1039/C8EE01651H
[16] Yang Y Q, Tang Y, Liang S Q, et al. Transition metal ion-preintercalated V2O5 as high-performance aqueous zinc-ion battery cathode with broad temperature adaptability. Nano Energy, 2019, 61: 617 doi: 10.1016/j.nanoen.2019.05.005
[17] Liu X D, Liu C Y, Wang Z Q, et al. Facile hydrothermal synthesis of V2O5 nanofibers as cathode material for aqueous zinc-ion batteries. J Alloys Compd, 2022, 896: 163071 doi: 10.1016/j.jallcom.2021.163071
[18] Wang X Y, Ma L W, Zhang P C, et al. Vanadium pentoxide nanosheets as cathodes for aqueous zinc-ion batteries with high rate capability and long durability. Appl Surf Sci, 2020, 502: 144207 doi: 10.1016/j.apsusc.2019.144207
[19] Chen L L, Yang Z H, Cui F, et al. Enhanced rate and cycling performances of hollow V2O5 nanospheres for aqueous zinc ion battery cathode. Appl Surf Sci, 2020, 507: 145137 doi: 10.1016/j.apsusc.2019.145137
[20] Yong B, Ma D T, Wang Y Y, et al. Understanding the design principles of advanced aqueous zinc-ion battery cathodes: From transport kinetics to structural engineering, and future perspectives. Adv Energy Mater, 2020, 10(45): 2002354 doi: 10.1002/aenm.202002354
[21] Liu S C, Zhu H, Zhang B H, et al. Tuning the kinetics of zinc-ion insertion/extraction in V2O5 by in situ polyaniline intercalation enables improved aqueous zinc-ion storage performance. Adv Mater, 2020, 32(26): 2001113 doi: 10.1002/adma.202001113
[22] Yin B S, Zhang S W, Ke K, et al. Binder-free V2O5/CNT paper electrode for high rate performance zinc ion battery. Nanoscale, 2019, 11(42): 19723 doi: 10.1039/C9NR07458A
[23] Gao H Y, Wu Q Q, Guo M, et al. Rationally fabricating nitrogen-doped carbon coated nanocrystalline Li2FeSiO4@N–C with excellent Li-ion battery performances. Electrochim Acta, 2019, 318: 720 doi: 10.1016/j.electacta.2019.06.078
[24] Bai Y C, Zhang H, Hu Q, et al. Tuning the kinetics of binder-free ammonium vanadate cathode via defect modulation for ultrastable rechargeable zinc ion batteries. Nano Energy, 2021, 90: 106596 doi: 10.1016/j.nanoen.2021.106596
[25] Shi Z L, Xu W G, Ru Q, et al. Mn-doped K0.23V2O5 nanobelts as cathode materials for high performance flexible all-in-one zinc ion batteries. J Power Sources, 2021, 516: 230699 doi: 10.1016/j.jpowsour.2021.230699
[26] Guan X R, Sun Q C, Sun C L, et al. Tremella-like hydrated vanadium oxide cathode with an architectural design strategy toward ultralong lifespan aqueous zinc-ion batteries. ACS Appl Mater Interfaces, 2021, 13(35): 41688 doi: 10.1021/acsami.1c11560
[27] Cai Y, Chua R, Huang S Z, et al. Amorphous manganese dioxide with the enhanced pseudocapacitive performance for aqueous rechargeable zinc-ion battery. Chem Eng J, 2020, 396: 125221 doi: 10.1016/j.cej.2020.125221
[28] Hu Z, Zhu Z Q, Cheng F Y, et al. Pyrite FeS2 for high-rate and long-life rechargeable sodium batteries. Energy Environ Sci, 2015, 8(4): 1309 doi: 10.1039/C4EE03759F
[29] Xiong L, Qu Z L, Shen Z Y, et al. In situ construction of ball-in-ball structured porous vanadium pentoxide intertwined with carbon fibers induces superior electronic/ionic transport dynamics for aqueous zinc-ion batteries. J Colloid Interface Sci, 2022, 615: 184 doi: 10.1016/j.jcis.2022.01.155
[30] 黄永烽, 黄文婷, 刘文宝, 等. 锌离子电池正极材料V2O5的储能机理和容量衰减原因. 高等学校化学学报, 2020, 41(8):1859 Huang Y F, Huang W T, Liu W B, et al. Mechanism of storage and capacity attenuation of V2O5 as cathode of zinc-ion battery. Chem J Chin Univ, 2020, 41(8): 1859