An n-type organic positive electrode material, a preparation method and application thereof

Abstract

The application discloses an n-type organic positive electrode material and a preparation method and application thereof, wherein pyridine diamine is reacted with hydroxybenzoquinone to synthesize an organic compound with a C=N bond on a benzene ring. The positive electrode material has a high specific capacity; a water-based zinc ion battery assembled from the electrode has a maximum theoretical specific capacity of 374 mAh g ‑1 , can release a specific capacity of nearly 286 mAh g ‑1 at a current density of 0.05 A g ‑1 , has a capacity retention rate of 74% (initial 128 mAh g ‑1 ) after 500 cycles at a current density of 5 A g ‑1 , and has a simple preparation method.

Description

Technical Field

[0001] This invention relates to aqueous zinc-ion battery cathode technology, and particularly to an n-type organic cathode material, its preparation method, and its application. Background Technology

[0002] In recent years, zinc-organic batteries have attracted widespread attention due to the tunable structure of organic cathode materials and the inherent advantages of high theoretical capacity and low cost of zinc anodes. Among various organic electrode materials, three redox mechanisms exist: n-type electrodes are reduced to a negatively charged state by accepting electrons, generally exhibiting a larger theoretical specific capacity; p-type electrodes are oxidized to a positively charged state by contributing electrons, generally exhibiting faster reaction kinetics; and bipolar electrodes possess characteristics of both n- and p-type electrodes. Currently, many p-type materials have been reported, such as nitroxide radical compounds, triphenylamine and its derivatives, triphenylphosphine and its derivatives, organosulfides, and organoselenides. However, due to the large molecular structure and relatively few active sites of p-type compounds, their theoretical and actual capacities are often unsatisfactory, typically below 200 mAh g⁻¹, which limits their application in large-scale energy storage. n-type organic compounds mainly include carbonyl compounds, imine compounds, and nitro compounds. Because n-type materials contain a rich variety of active groups that are readily available, and because n-type organic cathode materials have multiple active centers and low dead mass, they possess extremely high theoretical specific capacity and actual capacity. However, compared to p-type materials, n-type materials have a lower voltage, specifically below 0.8V relative to Zn / Zn2+, which limits their applications. Studies have shown that n-type materials undergo incompletely reversible H+ insertion and extraction during low-voltage discharge in aqueous zinc-ion batteries, affecting their long-cycle performance. Therefore, developing novel n-type materials with high operating voltage and long cycle life has significant practical value. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a simple method for synthesizing and preparing a high-capacity n-type organic cathode material with multiple active sites, as well as its application.

[0004] This invention synthesizes an n-type cathode material using a simple preparation method. This cathode material is an organic compound containing pyridine and pyrazine rings. This invention also discloses a method for preparing a hexaazapentabenzene electrode material, denoted as DHHAP. This invention provides capacity by allowing cations from the electrolyte to be inserted or removed during charge and discharge via C=N bonds in the organic compound.

[0005] Technical solution: The present invention provides a method for preparing n-type organic cathode materials, wherein pyridine diamine is reacted with hydroxybenzoquinone to synthesize an organic compound having C=N bonds on a benzene ring.

[0006] Furthermore, the method for preparing the n-type organic cathode material includes the following steps:

[0007] (1) Pyridine diamine and hydroxybenzoquinone were ground together;

[0008] (2) The mixed powder is heated to react;

[0009] (3) After the reaction is cooled to room temperature, the powder after the reaction is dispersed into the solution, the solution is filtered under vacuum to obtain a solid product, and then dried under vacuum to obtain a solid powder.

[0010] Furthermore, in step (1), the ratio of hydroxybenzoquinone to pyridinediamine is 1:(2-2.5).

[0011] Furthermore, in step (1), the sample of pyridine diamine should be added at a mass ratio of 2-2.5 times the stoichiometric ratio to ensure a complete reaction.

[0012] Further, in step (1), the pyridine diamine includes any one of pyrazine diamine, phenazine diamine, fluoropyridine diamine, chloropyridine diamine, or bromopyridine diamine.

[0013] Furthermore, in step (2), the heating reaction temperature is 150-180℃ and the reaction time is 4-12 hours.

[0014] Furthermore, in step (3), the vacuum drying temperature is 60-80℃, and the drying time is 8-12 hours.

[0015] The method described yields an n-type organic cathode material.

[0016] Furthermore, n-type organic cathode materials have the molecular formula Cn. 16 H 10 The N6,4,11-dihydro-4,6,7,11,13,14-hexaazapentabenzene electrode material, denoted as DHHAP, has the following structural formula:

[0017]

[0018] The preparation method of DHHAP electrode material includes the following steps:

[0019] 2,5-Dihydroxy-1,4-benzoquinone and 2,3-diaminopyridine were ground and mixed evenly, placed in a tube furnace and heated to react, and then the sample was washed and dried to obtain the final product DHHAP.

[0020] The chemical reaction formula for compound synthesis is as follows:

[0021]

[0022] Another aspect of the present invention provides the application of the aforementioned n-type organic cathode material in the cathode of an aqueous zinc-ion battery.

[0023] Furthermore, the method for preparing the aqueous zinc-ion battery cathode is to mix n-type organic cathode material with binder and conductive agent, roll it onto current collector, and then cure it to obtain the aqueous zinc-ion battery cathode.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The cathode material of this invention is an n-type organic material, which has a larger theoretical specific capacity; at 0.05A g -1 The cathode material has a current density of 286 mAh g. -1 The discharge specific capacity. The highest theoretical specific capacity of the aqueous zinc-ion battery assembled from this electrode can reach 374 mAh g. -1 , in 5A g -1 After 500 cycles at a current density, the capacity retention was 74% (initial 128mAh g). -1 ).

[0026] (2) In aqueous zinc-ion batteries, the low voltage of organic n-type electrode materials has always been a problem, but the n-type material of the present invention has a voltage relative to Zn / Zn 2+ The voltage is approximately 0.9V, which is higher than that of most reported n-type materials.

[0027] (3) DHHAP has active sites with multiple energy storage functional groups, which adsorb cations in the electrolyte during charging and discharging, providing good capacity.

[0028] (4) The preparation method of the present invention is a simple one-step reaction. Attached Figure Description

[0029] Figure 1 The above is the 1H NMR spectrum of the DHHAP cathode material in the example. 1 H NMR);

[0030] Figure 2 The mass spectrum of the DHHAP cathode material in the example is shown.

[0031] Figure 3 The image shown is a scanning electron microscope (SEM) image of the DHHAP cathode material in the embodiment.

[0032] Figure 4 In this example, the DHHAP cathode material is used at 0.5 mV s -1 CV curve at scan rate;

[0033] Figure 5The figures show the charge-discharge curves of the DHHAP cathode material at different current densities in the embodiments.

[0034] Figure 6 In the example, the DHHAP cathode material was tested at 5A g. -1 The charge-discharge curves at the current density. Detailed Implementation

[0035] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0036] The preparation method of the n-type organic cathode material for aqueous zinc-ion batteries provided in this example includes the following steps:

[0037] Step 1: Weigh 1.40g of 2,5-dihydroxy-1,4-benzoquinone and 1.09g of 2,3-diaminopyridine into a mortar and grind for 30 minutes;

[0038] Step 2: Place the evenly mixed powder into a ceramic boat and place it in a tube furnace to react at 150°C for 4 hours.

[0039] Step 3: After the reaction cools to room temperature, disperse the powder in water, filter the solution under vacuum to obtain a solid product, and dry it under vacuum at 80°C for 10 hours to obtain a solid powder.

[0040] Step 4: Take the above solid powder DHHAP as the positive electrode. The DHHAP composite material is: DHHAP, conductive carbon black and binder polytetrafluoroethylene PTFE are mixed in a mass ratio of 6:3:1, and isopropanol is used as solvent to knead into dough. The material is then rolled onto a stainless steel mesh using a roller press and vacuum dried at 80°C for 6 hours for later use.

[0041] The product in this embodiment underwent performance testing, and the results are as follows:

[0042] like Figure 5 As shown, the aqueous zinc-ion battery assembled using the DHHAP cathode material exhibits good rate performance at 0.05 A g. -1 0.1A g -1 0.5A g -1 1A g -1 3A g -1 and 5A g -1 At current densities, they respectively have 286 mAh g -1 237mAh g -1 173mAh g -1 145mAh g -1 127mAh g-1 and 128mAh g -1 Its maximum initial discharge specific capacity is superior to most and reported organic cathode materials for aqueous zinc-ion batteries.

[0043] like Figure 6 As shown, the aqueous zinc-ion battery assembled using the DHHAP cathode material exhibits good long-cycle performance at 5A g. -1 Under high current density, it can maintain 74% capacity retention after 500 cycles (initial 128mAh g). -1 ).

[0044] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for preparing a positive electrode for an aqueous zinc-ion battery, characterized in that, Includes the following steps: (1) Weigh and grind 2,5-dihydroxy-1,4-benzoquinone and 2,3-diaminopyridine in a molar ratio of 1:2, react at 150°C for 4 hours, cool, wash, and vacuum dry at 80°C for 10 hours to obtain solid powder DHHAP. (2) The DHHAP, conductive carbon black and polytetrafluoroethylene binder obtained in step (1) are mixed in a mass ratio of 6:3:1, isopropanol solvent is added and kneaded into a ball, which is then rolled onto a stainless steel mesh current collector by a roller press and then vacuum dried at 80°C for 6 hours to obtain the positive electrode.

2. An aqueous zinc-ion battery cathode prepared by the method of claim 1, characterized in that, Aqueous zinc-ion batteries assembled using this positive electrode exhibit the following performance: a. At 0.05 A g -1 At current density, the initial discharge specific capacity is 286 mAh g. -1 It also has a discharge voltage plateau of 0.9V relative to Zn / Zn²⁺; b. In 1 A g -1 The capacity-rate inflection point appears at the current density, when the current density increases from 1 A g. -1 Increased to 5 Ag -1 At that time, the capacity retention rate is ≥88%; c. In 5 A g -1 After 500 cycles at the current density, the capacity decay rate in the last 300 cycles is ≤0.01% / cycle.

3. An aqueous zinc-ion battery comprising the positive electrode of claim 2.

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