阅读说明：本技术 一种抑制氧化锌负极钝化的复配电解液 (Compound electrolyte for inhibiting passivation of zinc oxide cathode ) 是由 杨建文 熊伟雄 刘鑫鑫 倪文浩 黄斌 李伟 于 2021-06-02 设计创作，主要内容包括：本发明公开了一种抑制氧化锌负极钝化行为的复配电解液。还原态氧化锌电极在Li-2SO-4-Na-2SO-4-ZnSO-4复配水溶液中进行阳极极化时会发生显著的钝化行为,在Li-2SO-4-Na-2SO-4-ZnSO-4复配水溶液中加入(NH-4)-2SO-4并调节其pH至9.0,可以有效抑制氧化锌负极的钝化行为,获得大于540mAh g～(-1)的可逆充放电比容量。因此,该复配电解液用于水系锌电池具有良好的应用前景。(The invention discloses a compound electrolyte for inhibiting passivation behavior of a zinc oxide cathode. Reduced zinc oxide electrode in Li 2 SO 4 ‑Na 2 SO 4 ‑ZnSO 4 Significant passivation behavior occurs during anodic polarization in compounded aqueous solutions, in Li 2 SO 4 ‑Na 2 SO 4 ‑ZnSO 4 Adding (NH) into the compound aqueous solution 4 ) 2 SO 4 And the pH value is adjusted to 9.0, so that the passivation behavior of the zinc oxide cathode can be effectively inhibited, and more than 540mAh g is obtained ‑1 The reversible charge-discharge specific capacity of (2). Therefore, the temperature of the molten metal is controlled,the compound electrolyte has good application prospect when being used for a water-based zinc battery.)

1. A compound electrolyte for inhibiting passivation of a zinc oxide cathode is characterized by comprising the following specific steps:

(1) dissolving commercially available analytically pure lithium sulfate, sodium sulfate and zinc sulfate in deionized water to prepare a composition (0.2-2.4) MLi₂SO₄+(0.1～1.4)MNa₂SO₄+(0.1～3.0)MZnSO₄The aqueous solution of (1) is used as a compound electrolyte solution I;

(2) adding (0.1-5.7) M (NH) to the electrolyte (1)₄)₂SO₄Using 7MNH₃·H₂O solution and 0.2MH₂SO₄Regulating the pH value of the solution to 9.0 to obtain compound electrolyte II;

(3) mixing commercially available zinc oxide, graphite and acetylene black according to a mass ratio of (70-90) to (5-10) to (5-20) to prepare slurry, coating the slurry on an deoiled 30-mesh to 50-mesh brass net, wherein the coating area is 1cm multiplied by 1cm, the thickness is 0.10mm to 0.20mm, and then drying the coated slurry in a blast drying oven at the temperature of 80-100 ℃ for 4h to 16h to obtain a zinc oxide electrode, wherein the load mass of ZnO is 25mg to 30 mg;

(4) when the zinc oxide electrode of claim 3 is depolarized in the compound electrolyte of claim 1, 390-420 mAhg can be obtained^-1The reversible specific capacity of (a);

(5) 540mAhg can be obtained by depolarizing the zinc oxide electrode of claim 3 in the electrolyte of claim 2 so that its anodic passivation is effectively inhibited^-1The above reversible specific capacity;

(6) the zinc oxide electrode of claim (3) is not limited to zinc oxide as an active material, and other compounds containing zinc elements such as zinc phosphate, lithium zinc phosphate, calcium zinc phosphate, magnesium zinc phosphate, etc., as well as metallic zinc flakes, metallic zinc powder, etc. can be used as an electrode active material;

(7) the zinc-containing electrode active material of claim (6), having similar reversible electrochemical zinc storage behavior and performance in the electrolytes of claim (4) and claim (5).

Technical Field

The invention relates to the field of zinc electrode electrolyte, in particular to a preparation method of electrolyte for a zinc oxide cathode.

Background

The metal zinc has low standard potential, high specific capacity, rich resources and environmental protection, and is a chemical power supply cathode material with better comprehensive performance. Zinc cells (such as alkaline zinc-manganese dry cells, zinc-nickel cells, zinc-silver cells, etc.) using strongly alkaline electrolytes have been commercialized, but due to the presence of a large amount of OH in the strongly alkaline electrolyte^-The zinc cathode can be dissolved by chemical reaction, which causes the problems of electrode deformation, battery capacity attenuation and the like. Thus, OH in the strongly alkaline electrolyte is reduced^-The non-strong alkaline electrolyte is expected to improve the electrochemical stability of the zinc cathode material. However, in the weakly alkaline electrolyte, the passivation behavior of zinc hydroxide and zinc oxide insoluble compounds generated by the hydrolysis of zinc ions on the surface of metal zinc will seriously affect the charge and discharge kinetics process of the battery.

Based on the preparation method, the alkalescent compound electrolyte is prepared, and the surface passivation behavior of the zinc oxide negative electrode material is effectively inhibited.

Disclosure of Invention

The invention aims to provide a preparation method of a compound electrolyte for inhibiting passivation of a zinc oxide cathode.

The method comprises the following specific steps:

(1) with Li₂SO₄、Na₂SO₄、ZnSO₄Is used as solute and deionized water is used as solvent, and the preparation composition is 1.0MLi₂SO₄+1.2MNa₂SO₄+0.17MZnSO₄The compound aqueous solution of (1) is used as an electrolyte solution I; adding 1.2M (NH) on the basis of the electrolyte solution I₄)₂SO₄And controlling the pH to be 9.0 to obtain the compound electrolyte II.

(2) Mixing commercial ZnO, graphite and acetylene black according to a mass ratio of 80:5:15, grinding for half an hour, adding a proper amount of ethanol and 30 wt% of PTFE emulsion, continuously grinding to be in a nearly dry slurry shape, uniformly coating on a pre-deoiled brass net, wherein the coating area is 1cm multiplied by 1cm, the thickness is 0.2mm, drying for 8 hours in a blast drying oven at the temperature of 80 ℃ to obtain the zinc oxide electrode plate, and the loading mass of ZnO is about 24 mg.

(3) Taking the zinc oxide electrode slice prepared in the step (2) as a research electrode, Hg/Hg₂SO₄And (3) taking the electrode as a reference electrode and the carbon rod as an auxiliary electrode, and testing a cyclic voltammetry curve and a chronopotentiometry curve of the zinc oxide electrode in the electrolyte prepared in the step (1) by using an electrochemical workstation. Wherein, the potential window of the cyclic voltammetry test is-0.5V to-2.1V, and the potential scanning rate is 10mVs^-1(ii) a The current density for the chronopotentiometric test was 50 mA.

Drawings

FIG. 1 is a first cycle voltammetry curve of a zinc oxide electrode in two formulated electrolytes in an example of the present invention.

FIG. 2 is a first anodic polarization and cathodic polarization chronopotentiometric curves of a zinc oxide electrode in two complex electrolytes in an embodiment of the present invention.

Example (b):

the invention is further described below with reference to examples.

(1) Taking 11g of lithium sulfate (Li)₂SO₄Analytically pure, Guangdong Xiong Longong chemical Co., Ltd.), and 17.1g of sodium sulfate (Na)₂SO₄Analytically pure, Guangdong Xiong Longong chemical Co., Ltd.), and zinc sulfate 34.5g (ZnSO)₄·7H₂O, analytically pure, Guangdong Xiong chemical Co., Ltd.) was dissolved in 100mL of deionized water to prepare a solution having a composition of 1.0MLi₂SO₄+1.2MNa₂SO₄+0.17MZnSO₄The compound aqueous solution of (1) is used as an electrolyte solution I; adding 15.85g ammonium sulfate ((NH) based on the electrolyte I₄)₂SO₄Analytically pure, chemical engineering Limited, Guangdong west Longong, i.e., the molar concentration is 1.2M, and the pH is controlled to be 9.0, so that the compound electrolyte II is obtained;

(2) commercially available zinc oxide (ZnO, chemical purity, Guangdong Xiong chemical industry Co., Ltd.), graphite (chemical purity, Guangdong Xiong chemical industry Co., Ltd.), acetylene black (battery grade, Guangdong chemical industry import and export Co., Ltd.) were mixed in a mass ratio of 80:5:15, after grinding for half an hour, a proper amount of ethanol (analytical purity, Guangdong Xiong chemical industry Co., Ltd.) and 30 wt% of PTFE emulsion (Shanghai Sanaifu new material Co., Ltd.) were added, the mixture was continuously ground into a near dry slurry, and the slurry was uniformly coated on a pre-deoiled brass mesh (Industrial grade, Hebei east wire gauze Co., Ltd.), the coating area was 1cm × 1cm and the thickness was 0.2mm, and the electrode sheet was dried in an air-blast drying oven (DHX-9053A, Shanghai Macro apparatus Co., Ltd.) at 80 ℃ for 8 hours to obtain an electrode sheet with a ZnO load mass of about 24 mg.

(3) Taking the zinc oxide electrode prepared in the step (2) as a research electrode, Hg/Hg₂SO₄The electrode is used as a reference electrode, the carbon rod is used as an auxiliary electrode, and the cyclic voltammetry and chronopotentiometry curves of the zinc oxide electrode are tested on an electrochemical workstation (CHI760E, Shanghai Chenghua instruments, Inc.) by using the electrolyte prepared in the step (1).

The potential window of the cyclic voltammetry test is-0.5V to-2.1V, and the potential scanning rate is 10mVs^-1The test result is shown in figure 1, and it can be seen that when the reduced zinc oxide electrode is scanned from a low potential to a high potential in the compound electrolyte (i), a passivation film appears to significantly separate two peaks of oxidation current, and when the compound electrolyte (ii) is adopted, the two peaks of oxidation current are combined and the peak of oxidation reduction current is significantly increased, which indicates that the passivation behavior of the electrode surface is significantly inhibited.

The zinc oxide electrode was subjected to chronopotentiometric performance testing with a 50mA current, and the results are shown in fig. 2, which shows that the zinc oxide electrode had two voltage platforms on the first anodic polarization curve in the first complex electrolyte, and that multiple voltage platforms were also present on the cathodic polarization curve, indicating that the electrode showed significant passivation behavior, and the first charge-discharge specific capacities were 391.3mAhg, respectively^-1And 411.4mAhg^-1(ii) a On the contrary, in the complex electrolyte II, double potential platforms are not obvious on a zinc oxide electrode first anode polarization curve, a plurality of voltage platforms do not appear on a cathode polarization curve, the passivation behavior of the electrode surface is effectively inhibited, and the first charge-discharge specific capacity is 548.2mAhg^-1And 599.5mAhg^-1。