Nanoporous PANI/ZnO/ ${VO}_{2}$ ternary nanocomposite and its electrolyte for green supercapacitance
纳米多孔 PANI/ZnO/ ${VO}_{2}$ 三元纳米复合材料及其用于绿色超电容的电解质

◻

Aranganathan Viswanathan *, Adka Nityananda Shetty
Aranganathan Viswanathan *， Adka Nityananda ShettyDepartment of Chemistry, National Institute of Technology Karnataka, Surathkal, Srinivasanagar, Mangalore 575025, India
卡纳塔克邦国家理工学院化学系，印度芒格洛尔 575025 Srinivasanagar 苏拉特卡尔

ARTICLE INFO 文章信息

Keywords 关键字

By-product electrolyte  副产品电解质
Green supercapacitance  绿色超电容
PANI  聚苯胺
Acidified supernatant liquid
酸化上清液
Zinc oxide  氧化锌

Abstract 抽象

The green process of energy storage by utilizing the by-product obtained after the synthesis of PANI54.69 %: ZnO .81 %: ${VO}_{2} 37.50$ % ( PZnV ) nanocomposite by insitu single step method, as its electrolyte is demonstrated herein. This green approach yields $23 %$ improvement in the energy storage compared to that in the presence of $1 M H_{2} {SO}_{4}$ . The enhanced energy storage obtained for PZnV nanocomposite in the presence of acidified byproduct are a specific capacitance $(C_{s})$ of $177.3 F g^{- 1}$ , a specific capacity $(Q)$ of $212.7 C g^{- 1}$ , an energy density $(E)$ of $35.46 Wh {kg}^{- 1}$ (comparable with $E$ of lead acid batteries), and a power density $(P)$ of $1.632 kW {kg}^{- 1}$ at $1 {Ag}^{- 1}$ . The PZnV exhibited an unique feature of increase in energy storage with increase in No. of CV cycles in the presence of $1 M H_{2} {SO}_{4}$ , and the maximum energy storage was achieved after 12,312 cycles with a $C_{s}$ of 440.5 $F g^{- 1}$ , a $Q$ of $528.6 C g^{- 1}$ , an $E$ of $88.10 Wh {kg}^{- 1}$ (comparable with $E$ of Li-ion batteries), and a $P$ of 2.154 kW ${kg}^{- 1}$ . A good cyclic stability up to 16,812 cycles was achieved at $0.4 V s^{- 1}$ .
利用原位单步法合成 PANI54.69 %： ZnO .81 %： ${VO}_{2} 37.50$ % （ PZnV ）纳米复合材料后获得的副产物进行绿色储能，其电解质在此得到证明。 $23 %$ 与存在 $1 M H_{2} {SO}_{4}$ .在酸化副产物存在下，PZnV 纳米复合材料获得的增强储能是比电容 $(C_{s})$ 、 $177.3 F g^{- 1}$ 比容量 $(Q)$ $212.7 C g^{- 1}$ 、能量密度 $(E)$ $35.46 Wh {kg}^{- 1}$ （与 $E$ 铅酸电池相当）和功率密度 $(P)$ $1.632 kW {kg}^{- 1}$ at $1 {Ag}^{- 1}$ 。PZnV 表现出储能增加的独特特征，编号增加。在 $1 M H_{2} {SO}_{4}$ 存在的情况下进行 CV 循环，并且在 12,312 次循环后实现了最大能量存储，其中 a $C_{s}$ 为 440.5 $F g^{- 1}$ 、 a $Q$ 为 $528.6 C g^{- 1}$ 、为 $E$ $88.10 Wh {kg}^{- 1}$ （与 $E$ 锂离子电池相当）和 a $P$ 为 2.154 kW ${kg}^{- 1}$ 。在时实现了高达 16,812 次循环的良好 $0.4 V s^{- 1}$ 循环稳定性。

1. Introduction 1. 引言

The toxicity of organic electrolytes (OEs) compared to that of aqueous electrolytes (AEs) is an indispensable matter of concerns. The great merit of the organic electrolytes is their high operation potential (3.5 V) despite of their shortcomings like, poor ionic conductivity, toxicity, incompatibility with environment, and high cost [1,2]. Another class of electrolytes, the ionic liquids (ILs) are also capable of offering operation potential (

4.5 V [1]

) higher than that of OEs but they also have similar shortcoming as those of OEs. The AEs exhibit high electric conductivity, good ionic mobility and easy environmental decomposition compared to that of OEs but offer operational window as low as 1.2 V . The high electric conductivity and ionic mobility of AEs drive their better diffusion into the electrode materials. The high ionic strength and low ionic radius of aqueous electrolytes than those of OEs and ILs fetch high power in their presence [1]. The potential window is very significant in determining the quantity of energy storage as the potential window is directly proportional to energy density (

E

) of a device [3]. Considering the higher electric conductivity of AEs, achieving the

E

closer to

E

achieved in the presence of OEs is possible. For this purpose, the complete utilization of 1.2 V offered by any AEs is essential. This utilization of 1.2 V of AEs depends on various parameters like concentration of the AEs, electric conductivity of AEs, internal resistance (IR) of
与水性电解质（AE）相比，有机电解质（OE）的毒性是一个不可或缺的问题。有机电解质的最大优点是其高工作潜力（3.5 V），尽管它们存在离子电导率差、毒性大、与环境不相容和成本高等缺点 [1,2]。另一类电解质，离子液体（ILs）也能够提供比 OE 更高的作电位（

4.5 V [1]

），但它们也具有与 OE 相似的缺点。与 OE 相比，AE 表现出高导电性、良好的离子迁移率和易环境分解，但提供低至 1.2 V 的作窗口。AE 的高电导率和离子迁移率促使它们更好地扩散到电极材料中。与 OE 和 IL 相比，水性电解质的高离子强度和低离子半径在它们存在下获得了高功率 [1]。电势窗口在确定储能量方面非常重要，因为电势窗口与器件的能量密度（

E

）成正比 [3]。考虑到 AE 的较高导电性，在 OE 存在下实现

E

更接近

E

实现是可能的。为此，必须充分利用任何 AE 提供的 1.2 V。1.2 V AE 的利用率取决于各种参数，如 AE 的浓度、AE 的电导率、内阻（IR）
the electrode materials and IR loss of the device, mode of fabrication of energy storage device, potentials of redox reactions, current used for charging and discharging, nature of current collectors and dielectric materials.
器件的电极材料和红外损耗、储能器件的制造方式、氧化还原反应的电位、用于充电和放电的电流、集流体和介电材料的性质。

It is known that the oxidative polymerization process of aniline in the presence of an acid dopant results in polyaniline (PANI), as product and some byproducts, which are aqueous soluble. When ammounium persulphate

({({NH}_{4})}_{2} S_{2} O_{8})

is used as the oxidizing agent for the production of PANI, the by-products obtained are ammonium sulphate

({({NH}_{4})}_{2} {SO}_{4})

and sulphuric acid

(H_{2} {SO}_{4})

[4,5], which are themselves AEs and can be used as electrolytes. Depending on the conditions of polymerization, the pH and extent of formation of these electrolytes change. In addition, the ionic concentration of these byproducts would be unknown due to their in situ synthesis and so in order to increase the ionic concentrations of it, other aqueous dissolving electrolytes can be added and thus the entire chemical property of the electrolyte is altered favorably. However, the synthesis of PANI in controlled conditions would help in fixing the concentration of the byproducts formed. Yet the composition of these by-product electrolytes can be changed, when the PANI is synthesized with other entities like metal oxide/hydroxide, reduced graphene oxide, etc., in an in situ method.
众所周知，苯胺在酸掺杂剂存在下的氧化聚合过程产生聚苯胺（PANI）作为产物和一些副产物，它们是水溶性的。当使用过硫酸

({({NH}_{4})}_{2} S_{2} O_{8})

铵作为氧化剂生产 PANI 时，得到的副产物是硫酸铵

({({NH}_{4})}_{2} {SO}_{4})

和硫酸

(H_{2} {SO}_{4})

[4,5]，它们本身就是 AE，可以用作电解质。根据聚合条件，这些电解质的 pH 值和形成程度会发生变化。此外，由于这些副产物的原位合成，其离子浓度是未知的，因此为了增加其离子浓度，可以添加其他水性溶解电解质，从而有利地改变电解质的整个化学性质。然而，在受控条件下合成 PANI 将有助于固定形成的副产物的浓度。然而，当 PANI 与金属氧化物/氢氧化物、还原氧化石墨烯等其他实体在原位方法中合成时，这些副产品电解质的组成可以改变。

Herein, one such approach of using the byproducts obtained as supernatant liquid after the synthesis of

PANI / ZnO / {VO}_{2}

( PZnV )
在此，使用合成

PANI / ZnO / {VO}_{2}

（ PZnV ）后获得的副产物作为上清液的一种方法

Fig. 1. a) XRD spectrum, b) FT-IR spectra obtained adopting KBr pellet method and c) ATR method, of PZnV nanocomposite.
图 1.pZnV 纳米复合材料的 a） XRD 光谱，b）采用 KBr 颗粒法获得的 FT-IR 光谱和 c） ATR 方法。
nanocomposite as its electrolyte for energy storage purpose after acidifying it with Conc.

H_{2} {SO}_{4}

(acidified supernatant liquid) and comparing its energy storage results with the those obtained in the presence of 1 M

H_{2} {SO}_{4}

are made, and which is one of the aims of this study. The constituents of PZnV , (PANI, ZnO and

{VO}_{2}

) are abundant and inexpensive. The theoretical

C_{s}

of PANI and

{VO}_{2}

are as high as

2000 {Fg}^{- 1}

and 1181 F
纳米复合材料作为其用于储能目的的电解质，在用 Conc.

H_{2} {SO}_{4}

（酸化上清液）酸化后，将其储能结果与在 1 M

H_{2} {SO}_{4}

存在下获得的能量存储结果进行比较，这是本研究的目的之一。PZnV 的成分（PANI、ZnO 和

{VO}_{2}

）丰富且价格低廉。PANI 的理论

C_{s}

值和

{VO}_{2}

均高达

2000 {Fg}^{- 1}

1181 F

g^{- 1}

[6], respectively. The

V^{x +}

{VO}_{2}

can exist in multiple oxidation states [7] depending on the redox reactions that it undergo with electrolytes in the presence of applied potential or current and the ZnO is one of the widely used supercapacitor’s electrode materials due to its high theoretic

C_{s}

[8].

g^{- 1}

[6] 中。of

V^{x +}

{VO}_{2}

可以以多种氧化态存在 [7]，具体取决于它在外加电位或电流存在下与电解质发生的氧化还原反应，ZnO 由于其高理论性

C_{s}

[8] 而成为广泛使用的超级电容器的电极材料之一。

Generally, most of the synthetic methods of ZnO like mechanochemical process, precipitation process, precipitation in the presence of surfactants, sol-gel methods, solvothermal, hydrothermal and microwave techniques, emulsion, microemulsion, thermal decompositions, etc., involve either high temperatures or longer time for its synthesis [9]. The synthesis of ZnO in chemical reduction methods in aqueous medium at temperature less than

100^{\circ} C

is scarcest. Herein this work attempts are made to synthesize the ZnO by conducting the synthesis of two metal oxides together at the same conditions anticipating that the electrons involved in the chemical reduction process would bring about products different from what were expected, normally, which is another aim of this work. Here in this case the two metal precursor chosen were of vanadium and zinc, and the chemical reduction was conducted at temperature

< 90^{\circ} C

for 2.5 h at the pH of 14 using hydrazine hydrate as reducing agent. This attempt yielded products of

{VO}_{2}

and ZnO , while the expected products in the similar experimental conditions were

V_{2} O_{5}

and

Zn (OH)_{2}

as reported in [7] and [10], respectively. This difference in obtained products is due to the combined effect of synthesizing two metal oxides together, and the energy storage such attained materials are discussed here in the form of their composite with PANI. The presence of more than one metal oxide in a system is expected to contribute more electrons towards energy storage and in turn increase the overall energy storage of the material. So is this study. In addition, this type of
一般来说，ZnO 的大多数合成方法，如机械化学过程、沉淀过程、表面活性剂存在下的沉淀、溶胶-凝胶法、溶剂热、水热和微波技术、乳液、微乳液、热分解等，都涉及高温或更长的合成时间 [9]。在低于温度的

100^{\circ} C

水性介质中，通过化学还原方法合成 ZnO 是最稀缺的。在此，这项工作尝试通过在相同条件下将两种金属氧化物合成在一起来合成 ZnO，预计参与化学还原过程的电子会产生与正常预期不同的产物，这是这项工作的另一个目标。在这种情况下，选择的两种金属前驱体是钒和锌，使用水合肼作为还原剂，在 pH 值为 14 的温度下

< 90^{\circ} C

进行化学还原 2.5 小时。这一尝试产生了和 ZnO 的

{VO}_{2}

产物，而在相似实验条件下的预期产物分别为

V_{2} O_{5}

和

Zn (OH)_{2}

[7] 和 [10] 中报道的。所获得产物的这种差异是由于两种金属氧化物合成在一起的综合效应，并且这种获得的材料在这里以它们与 PANI 的复合形式讨论其能量存储。预计系统中存在不止一种金属氧化物将为能量存储贡献更多电子，进而增加材料的整体能量存储。这项研究也是如此。此外，这种类型的

Fig. 2.

a - e

) FE-SEM images of PZnV at nanoscales.
图 2.

a - e

） PZnV 在纳米尺度上的 FE-SEM 图像。

Fig. 3. a) XPS survey spectra; core level spectra of, b) C 1 s ; c) N 1 s ; d) O 1 s ; e) V 2 p and f) Zn 2 p .
图 3.a） XPS 测量光谱;核心能级光谱，b） C 1 s ;c） N 1 秒;d） O 1 秒;e） V 2 p 和 f） Zn 2 p .

Table 1 表 1
The energy storage parameters of PZnV , after different number of cycles at 1 A

g^{- 1}

.
PZnV 的储能参数，在 1 A

g^{- 1}

下经过不同的循环次数后。

No. of cycles 不。循环次数	$C_{s} (F g^{- 1})$	$Q (C g^{- 1})$	$E (W h {kg}^{- 1})$	$P (kW {kg}^{- 1})$	$η (%)$
$0$	144.1	172.9	28.81	1.553	87.20
$5989$	268.1	321.7	53.61	1.633	61.29
$12, 312$	440.5	528.6	88.10	2.154	57.54
$16, 812$	354.6	425.5	70.92	2.174	55.11

electrode mainly chosen to impart high energy character to the supercapacitor without compromising with the high power character. The PANI is the source of energy density and power density, while ZnO and

{VO}_{2}

are the sources of energy density.
选择电极主要是为了赋予超级电容器高能量特性，而不影响高功率特性。PANI 是能量密度和功率密度的来源，而 ZnO 和

{VO}_{2}

是能量密度的来源。

In the present study, the ternary nanocomposite of PANI, ZnO and

{VO}_{2}

are synthesized by insitu procedure and its supercapacitance was studied under two electrolytic conditions viz.,

1 M H_{2} {SO}_{4}

and acidified supernatant liquid (byproduct). The structural, electrochemical observations and discussion are as follow.
在本研究中，通过原位程序合成了 PANI、ZnO 的

{VO}_{2}

三元纳米复合材料及其超电容，在两种电解条件下，即酸

1 M H_{2} {SO}_{4}

化上清液（副产物）。结构、电化学观察和讨论如下。

2. Experimental 2. 实验

2.1. Synthesis of polyaniline/zinc oxide/vanadium oxide (PANI/ZnO/ ${VO}_{2}$ ) ( PZnV ) nanocomposite
2.1. 聚苯胺/氧化锌/氧化钒（PANI/ZnO/ ${VO}_{2}$ ）（ PZnV ）纳米复合材料的合成

350 μ L

of aniline was stirred in 100 mL of distilled water for 15 min , followed by the addition of 1.050 g of ammonium persulfate dissolved in a minimum amount of distilled water and 5 mL of 2 M methane sulphonic acid (MSA). The stirring was continued for 5 h at room temperature and the pH of the content was increased to 14 by using 6 M NaOH . Then, 2 mL of hydrazine hydrate was added to the reaction content and the content was stirred at a temperature of

90^{\circ} C

for 2 h . After 2 h of reduction process 28.94 mL of 0.1 M vanadyl sulphate pentahydrate

({VOSO}_{4} .5 H_{2} O)

and 6.5 mL of 1 M zinc sulphate

({ZnSO}_{4} \cdot 7

H_{2} O

) were added and stirring was continued at low temperature for 30 min. Then, the resulted product was purified by the procedure mentioned in [11]. There by, the methane sulphonic acid doped PANI/

ZnO / {VO}_{2} (PZnV)

nanocomposite was obtained. The assumed weight percentages of polyaniline, zinc oxide and vanadium oxide are

54.69 %

7.81 %

and

37.50 %

, respectively. Here, the formations of ZnO and

{VO}_{2}

are due to the combined effect of insitu synthesis. The attempts made using the same synthetic method without the precursors of any one of these constituents, particularly of metal oxides did not results in their respective binary composites rather it exhibited a different composite

350 μ L

将苯胺在 100 mL 蒸馏水中搅拌 15 分钟，然后加入 1.050 g 溶于微量蒸馏水和 5 mL 2 M 甲烷磺酸（MSA）的过硫酸铵。在室温下继续搅拌 5 h，并使用 6 M NaOH 将内容物的 pH 值增加到 14。然后，向反应内容物中加入 2 mL 水合肼，并在 2 h 的温度下

90^{\circ} C

搅拌内容物。还原过程 2 小时后，加入 28.94 mL 0.1 M 硫酸钒酸盐

({VOSO}_{4} .5 H_{2} O)

五水合物和 6.5 mL 1 M 硫酸

({ZnSO}_{4} \cdot 7

锌

H_{2} O

），并在低温下继续搅拌 30 分钟。然后，通过 [11] 中提到的程序纯化所得产物。由此，获得了甲烷磺酸掺杂的 PANI/

ZnO / {VO}_{2} (PZnV)

纳米复合材料。聚苯胺、氧化锌和氧化钒的假定重量百分比分别为

54.69 %

和

7.81 %

37.50 %

。在这里，ZnO 的

{VO}_{2}

形成是由于原位合成的综合作用。使用相同的合成方法进行的尝试，没有这些成分中的任何一种的前驱体，特别是金属氧化物的前驱体，并没有产生它们各自的二元复合材料，而是表现出不同的复合材料

- Corresponding author. 通讯作者。
E-mail address: ranguchemist@gmail.com (A. Viswanathan).
电子邮件地址：ranguchemist@gmail.com （A. Viswanathan）。
https://doi.org/10.1016/j.mseb.2024.117322
Received 11 January 2024; Received in revised form 26 February 2024; Accepted 16 March 2024
接收日期 2024 年 1 月 11 日;2024 年 2 月 26 日以修订版形式收到;录用日期 2024 年 3 月 16 日
Available online 20 March 2024
2024 年 3 月 20 日在线提供
0921-5107/© 2024 Elsevier B.V. All rights reserved.
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Nanoporous PANI/ZnO/ VO 2 VO 2 VO_(2)\mathrm{VO}_{2} ternary nanocomposite and its electrolyte for green supercapacitance 纳米多孔 PANI/ZnO/ VO 2 VO 2 VO_(2)\mathrm{VO}_{2} 三元纳米复合材料及其用于绿色超电容的电解质