CN115966781A

CN115966781A - Zinc ion battery electrolyte additive and electrolyte

Info

Publication number: CN115966781A
Application number: CN202211651969.6A
Authority: CN
Inventors: 乐士儒
Original assignee: Heilongjiang Nernst New Energy Technology Co ltd
Current assignee: Heilongjiang Nernst New Energy Technology Co ltd
Priority date: 2022-12-21
Filing date: 2022-12-21
Publication date: 2023-04-14

Abstract

The invention provides an electrolyte additive and electrolyte of a zinc ion battery, belonging to the field of new energy materials and electrochemistry, and the specific scheme is as follows: the additive comprises N, N-dimethyl-thiocarboxamide propane sodium sulfonate, and the molecular formula of the additive is shown as a formula I:

Description

Zinc ion battery electrolyte additive and electrolyte

Technical Field

The invention belongs to the field of new energy materials and electrochemistry, and particularly relates to an electrolyte additive and electrolyte for a zinc ion battery.

Background

Lithium ion batteries are widely applied in the fields of mobile phones, electric automobiles and the like, and are one of the application hotspots in the energy field at present. However, the large application of lithium ion batteries is limited by the constraint of insufficient lithium resources on the earth, and recently, the price of lithium carbonate is increased from original 4.2 ten thousand yuan/ton to 52 ten thousand yuan/ton; meanwhile, the lithium ion battery uses organic electrolyte, so that the use risks such as flammability and explosiveness exist, and the application of the lithium ion battery in the energy storage field with higher requirements on safety and cost is limited. The water system zinc ion battery takes metal zinc as a negative electrode, and the zinc has high abundance, high water environment tolerance and high theoretical specific mass capacity (820 mAh g) ^-1 ) And the advantages of low oxidation-reduction potential (-0.76V vs. SHE) and the like are considered as the preferential selection direction of the replaceable battery system of the lithium ion battery.

The zinc ion battery generally adopts cheap zinc foil as a negative electrode, and the electrolyte adopts weak-acid zinc sulfate and manganese sulfate. However, zinc dendrites are easily formed on the zinc cathode in the circulation process, the local current density is increased due to the formation of the dendrites, the speed of hydrogen precipitation in the water-based battery is accelerated, partial pH changes are caused due to the acceleration of hydrogen precipitation, basic zinc sulfate serving as a byproduct is formed, the surface unevenness is aggravated due to the accumulation of the basic zinc sulfate on the surface of the zinc cathode, the polarization is increased, and the growth of the zinc dendrites is aggravated due to the increase of the polarization. Therefore, the dendrite problem, the hydrogen evolution problem, the side reaction and the like are mutually influenced and aggravated, and the vicious circle causes that the deposition/stripping efficiency of the zinc cathode is extremely low, and is not beneficial to commercialization and wide application. Scientific researchers put forward measures such as designing a three-dimensional metal negative electrode, an artificial SEI film and using a high-concentration electrolyte aiming at the problem of poor reversibility of the deposition/stripping process of the zinc negative electrode, and the circulating reversibility of the zinc negative electrode is effectively improved. However, the problems of high cost, complex treatment, unsuitability for commercial popularization and the like still exist.

Disclosure of Invention

Aiming at the problems of dendritic crystals, hydrogen gas precipitation and negative products existing in the zinc cathode of the existing zinc ion battery, the invention does not adopt some expensive measures such as an artificial SEI film or high-concentration electrolyte, and the like, uses cheap N, N-dimethyl thiocarboxamide propane sodium sulfonate (DPS) as an electrolyte additive to be directly added on the electrolyte, thereby avoiding the generation of dendritic crystals and the generation of hydrogen gas and negative products, uses zinc foil as the cathode, and adopts the zinc foil as the cathode, and the zinc ion battery has the advantages of high efficiency, low cost, high safety and the like ^-2 The discharge cycle number can be increased from 70 circles to 2000 circles.

In order to achieve the purpose, the invention adopts the following technical scheme:

an additive for zinc ion battery electrolyte, which comprises N, N-dimethyl-thiocarboxamide propane sodium sulfonate and has a molecular formula shown in a formula I:

further, N-dimethylthiocarbonyl in the electrolyteThe concentration of the sodium aminopropane sulfonate is 2.0X 10 ^-4 g·L ^-1 -2.0×10 ^-1 g·L ^-1 。

The electrolyte of the zinc ion battery and the electrolyte additive.

Further, the electrolyte also comprises ZnSO ₄ And MnSO ₄ 。

Further, the ZnSO ₄ In a concentration of 2M, said MnSO ₄ The concentration of (3) is 0.5M.

The steps of assembling the battery using the above electrolyte are as follows:

the method comprises the following steps: preparing a manganese dioxide positive electrode material;

step two: preparing a negative pole piece;

step three: preparing electrolyte solution of 2M ZnSO ₄ +0.5M MnSO ₄ Adding an electrolyte additive of N, N-dimethyl-thiocarboxamide sodium propane sulfonate for stirring;

step four: and assembling the positive electrode shell, the positive electrode plate, the diaphragm, the electrolyte, the negative electrode plate, the gasket, the elastic sheet and the negative electrode shell in sequence, compacting the battery by using a tablet press, and performing subsequent testing.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention has cheap raw materials and no pollution.

2. The preparation process is simple and feasible, and only a small amount of N, N-dimethyl-thiocarboxamide propane sodium sulfonate is required to be added into the electrolyte as an additive according to the concentration requirement, and the battery is assembled.

3. The strong interaction between the sulfonic acid group and the zinc surface enables the zinc surface to generate chemical adsorption, the surface energy of zinc is changed, the sulfonic acid group covered on the surface of the zinc cathode enables the energy of the protruding tip to be minimized, and the uneven appearance can be smoothened. Thiocarboxamides with Zn ²⁺ Has larger binding energy and partially replaces Zn ²⁺ Water molecules in the shell are solvated to change the solvent shell structure of hydrated zinc ions, and desolvation is realized. The combined action of the zinc oxide and the zinc oxide realizes no byproduct generation and no dendritic crystal generation of the zinc cathode, and has good circulation stability.

Drawings

FIG. 1: a molecular formula schematic diagram of N, N-dimethyl thiocarboxamide propane sodium sulfonate;

FIG. 2 is a schematic diagram: XRD patterns of negative electrode surface products in different electrolyte systems;

FIG. 3: SEM photograph of zinc foil of Zn symmetrical battery after constant current charging and discharging, (a) is N, N-dimethyl thiocarboxamide propane sodium sulfonate (DPS) concentration of 2.0 × 10 in electrolyte system ^-3 g·L ^-1 Discharge current 4.4 mA/cm ^-2 SEM photograph of zinc foil corresponding to 2000 cycles of circulation, wherein (b) is the concentration of sodium N, N-Dimethylthiocarboxamide Propane Sulfonate (DPS) in the electrolyte system is 2.0 × 10 ^-4 Discharge current 1.0 mA/cm ^-2 Circulating a corresponding zinc foil SEM picture for 1000 circles, (c) circulating a corresponding zinc foil SEM picture for 50 circles without adding N, N-dimethyl thiocarboxamide propane sodium sulfonate (DPS) in the electrolyte; (d) SEM photograph of the original zinc foil;

FIG. 4 is a schematic view of: the constant current charge-discharge cycle curve of the Zn symmetrical battery is that the DPS concentration in the electrolyte is 2 multiplied by 10 ^-3 g·L ^-1 The current density is 4.4mA cm ^-2 ；

FIG. 5: constant current charge-discharge cycle curve of Zn symmetrical battery; DPS concentration in the electrolyte was 2X 10 ^-4 g·L ^-1 Current density of 1mA cm ^-2 ；

FIG. 6: mnO (MnO) ₂ |ZnSO ₄ +MnSO ₄ I Zn full cell cycle performance curve in 1Ag ^-1 The current density discharges.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings and embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the protection scope of the present invention.

Example 1

(1) And preparing the positive pole piece. Hydrothermal preparation of a-MnO ₂ And (3) nano-rods: 1.264g of KMnO ₄ Dissolving in 75mL of deionized water, adding 2mL of 98% ₂ SO ₄ And stirred for 15 minutes. It was transferred to a Teflon reactor (100 mL) and held at a temperature of 140 ℃ for 3.5h. After cooling to room temperature at the same temperature, the sample was centrifuged and washed 2-3 times with deionized water. Then, the sample was dried in an oven at 60 ℃ for 24 hours to obtain a-MnO ₂ . a-MnO ₂ : and (3) SuperP: PVDF (polyvinylidene fluoride) is 7:2:1, and then stirring on a magnetic stirrer for 24 hours; and uniformly coating the well-mixed positive paste on carbon paper with the diameter of 10mm, and drying in an oven at 60 ℃ for 24h.

(2) And preparing a negative pole piece. Punching a zinc foil into a pole piece with the thickness of 12mm, pressing for 5min under the pressure of 5MPa, then polishing the zinc piece by using 2000-mesh abrasive paper, placing the zinc piece in an ethanol solution, performing ultrasonic treatment for 5min, and naturally drying in the air to obtain the zinc electrode pole piece.

(3) And (4) preparing an electrolyte. By 2M ZnSO ₄ +0.5M MnSO ₄ Based on the electrolyte, an electrolyte additive of N, N-dimethyl-thiocarboxamide sodium propane sulfonate (DPS) is added, and the concentration is 2.0 multiplied by 10 ^-3 g·L ^-1 And stirring for 30min.

(4) And assembling the symmetrical battery according to the negative electrode shell, the negative electrode gasket, the negative electrode, the diaphragm, the electrolyte, the negative electrode gasket and the negative electrode shell.

(5) And assembling the positive electrode shell, the positive electrode plate, the diaphragm, the electrolyte, the negative electrode plate, the gasket, the elastic sheet and the negative electrode shell in sequence, and compacting the battery by using a tablet press.

This example was assembled with symmetrical batteries at 4.4mA.cm ^-2 After 2000 cycles of cycling, fig. 2 shows the XRD pattern of the product on the surface of the negative electrode, without the formation of basic zinc sulfate as a by-product. Fig. 3 (a) is an SEM photograph of the surface of the negative electrode after 2000 cycles of cycling of the symmetrical battery assembled in the present example, with no dendrite formation on the surface. The added sodium N, N-dimethyl-thiocarboxamide propane sulfonate is shown to inhibit the generation of dendrites, while FIG. 3 (c) is an SEM picture of the zinc foil after the battery is cycled when the electrolyte is not added with additives, and FIG. 3 (d) is an original zinc foil, and the SEM picture shows that the surface appearance of the zinc foil is rough and uneven, and is obviously different from that when DPS additives are added. FIG. 4 is a schematic diagram of a symmetrical battery at 4.4mA.cm ^-2 Cyclicity of dischargeThe stability is greatly improved after N, N-dimethyl-thiocarboxamide propane sodium sulfonate (DPS) is added. FIG. 6 shows MnO assembled in this embodiment ₂ |ZnSO ₄ +MnSO ₄ 1A g of Zn battery ^-1 Current density discharge cycling performance curve. The battery can stably circulate for 2000 circles, and the capacity is kept at 168mAh & g ^-1 The coulombic efficiency was greater than 98%.

Example 2

(1) And preparing a negative pole piece. Punching a zinc foil into a pole piece with the thickness of 12mm, pressing for 5min under the pressure of 5MPa, then polishing the zinc piece by using 2000-mesh abrasive paper, placing the zinc piece in an ethanol solution, performing ultrasonic treatment for 5min, and naturally drying in the air to obtain the zinc electrode pole piece.

(2) And (4) preparing an electrolyte. By 2M ZnSO ₄ +0.5M MnSO ₄ Based on the electrolyte, an electrolyte additive of N, N-dimethyl-thiocarboxamide sodium propane sulfonate (DPS) is added, and the concentration is 2.0 multiplied by 10 ^-4 g·L ^-1 。

(3) The symmetrical battery is assembled according to the negative electrode shell, the negative electrode gasket, the negative electrode, the diaphragm, the electrolyte, the negative electrode gasket and the negative electrode shell.

The symmetrical cell assembled in this example was at 1mA.cm ^-2 After 1000 cycles of circulation, fig. 2 shows the XRD pattern of the product on the surface of the cathode, without the by-product of basic zinc sulfate. Fig. 3 (b) is a SEM photograph of the surface of the assembled symmetrical cell of this example after 1000 cycles without severe dendrite formation on the surface. FIG. 5 shows a symmetrical cell at 1.0mA.cm ^-2 The discharge cycle performance chart shows that the stable cycle reaches 1000 circles.

Example 3

(2) Preparing electrolyte 2M ZnSO ₄ +0.5M MnSO ₄ 。

(3) And assembling the symmetrical battery according to the negative electrode shell, the negative electrode gasket, the negative electrode, the diaphragm, the electrolyte, the negative electrode gasket and the negative electrode shell.

The true bookExample assembled symmetrical cell at 1mA.cm ^-2 After 50 cycles, fig. 2 shows the XRD pattern of the product on the surface of the negative electrode, and the diffraction intensity of the Zn (002) plane diffraction peak is high, so that dendrite is more easily generated. Fig. 3 (c) is an SEM photograph of the surface of the negative electrode after cycling of the symmetrical cell assembled in this example, where dendrites were formed and the surface was uneven.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. The zinc ion battery electrolyte additive is characterized in that: the additive comprises N, N-dimethyl-thiocarboxamide propane sodium sulfonate, and the molecular formula of the additive is shown as a formula I:

2. the additive for zinc ion battery electrolyte according to claim 1, wherein: the concentration of the sodium N, N-dimethylthioformamide propane sulfonate in the electrolyte is 2.0 multiplied by 10 ^-4 g·L ^-1 -2.0×10 ^-1

g·L ^-1 。

3. The zinc ion battery electrolyte is characterized in that: comprising the electrolyte additive of claim 1 or 2.

4. The zinc ion battery electrolyte of claim 3, wherein: the electrolyte also comprises ZnSO ₄ And MnSO ₄ 。

5. According to claim 4The zinc ion battery electrolyte is characterized in that: the ZnSO ₄ In a concentration of 2M, said MnSO ₄ The concentration of (3) is 0.5M.