Anode powder for enhancing the safety of sodium-nickel single batteries

Abstract

The application discloses anode powder for enhancing safety of sodium-nickel single battery, which is prepared by uniformly mixing nickel powder and aluminum powder. The anode powder can effectively reduce the current density passing through the bottom of the ceramic tube, prevent the generation of the bottom crack of the ceramic tube, protect the steel shell from corrosion, and prolong the service life of the battery cell.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium nickel batteries, and particularly relates to an anode powder for enhancing the safety of sodium nickel single batteries. BACKGROUND

[0002] The sodium nickel battery, also known as a sodium salt battery or a sodium-nickel chloride battery, is a kind of high-temperature sodium battery, the positive electrode of which is solid-state NiCl2, the negative electrode is liquid-state Na, and the electrolyte is solid-state Na-beta"-Al2O3 ceramic. Sodium ions drift between the positive and negative electrodes through the ceramic electrolyte during charging and discharging. The sodium nickel battery is a green product with strong stability, high safety, long service life, wide application range, easy-to-obtain raw materials, no toxicity, simple recycling process and no pollution.

[0003] The solid electrolyte of the sodium nickel battery may cause cracks when the local current density is too large, thereby causing the failure of the battery cell. There are mainly the following two cases: 1. When the sodium nickel battery is in the initial formation stage, the local current concentration may cause cracks at the bottom of the ceramic tube at the moment when the liquid metal sodium drop at the bottom of the ceramic tube is in point contact with the steel shell bottom; 2. When the BMS of the battery pack fails to cause over-discharge of the battery cell, the local current density of the ceramic tube bottom is too large, which may also cause cracks at the bottom of the ceramic tube at the last moment before the liquid metal sodium drop between the ceramic tube bottom and the steel shell is out of point contact with the steel shell bottom. In addition, when the ceramic tube has been broken, a large amount of NaAlCl4 on the positive electrode side flows to the negative electrode side steel shell, and the entire failed battery cell becomes an electrolytic cell Ni / NaAlCl4 / Fe. When discharging, the steel shell undergoes an electrochemical reaction Fe-2e - →Fe 2+ , which causes the corrosion and even perforation of the steel shell, so that NaAlCl4 flows into the battery box.

[0004] Based on the occurrence of the above three cases, it is urgent to enhance the safety of the sodium nickel single battery. SUMMARY

[0005] In view of the existing technical problems, the application provides an anode powder for enhancing the safety of a sodium nickel single battery. The anode powder of the application can effectively reduce the current density through the bottom of the ceramic tube, prevent the generation of cracks at the bottom of the ceramic tube, and at the same time, protect the steel shell from corrosion and improve the service life of the battery cell.

[0006] The technical scheme adopted by the application is as follows:

[0007] An anode powder for enhancing the safety of a sodium nickel single battery, which is formed by uniformly mixing nickel powder and aluminum powder.

[0008] Further, the anode powder is tested by the Yeliefu method, and the water content is not more than 1500 ppm. When the water content is too high, the cohesion between the anode powder particles is greatly increased, the flowability of the powder is poor, the weight addition is not accurate during filling, the rework rate is high, and the production efficiency is affected. In addition, after the battery is filled with the positive electrode particles, there is a baking (287℃) step to dry the water in the particles. In this process, the aluminum powder in the anode powder reacts with the water to generate hydrogen, causing the battery to swell, affecting the subsequent qualification test and assembly. Therefore, strictly controlling the water content of the anode powder is crucial for the production and quality of the battery.

[0009] Further, the mass ratio of the aluminum powder and the nickel powder in the anode powder is 1:1 to 12:1.

[0010] Further, the nickel powder is a carbonyl nickel powder with a Fisher particle size of less than 10 μm. The carbonyl nickel powder is prepared by a carbonyl method and has a high purity, which is significantly higher than that of reduced nickel powder and electrolytic nickel powder. In addition, the carbonyl nickel powder has a unique crystal structure, and its surface can be tightly combined with the aluminum powder.

[0011] Preferably, the carbonyl nickel powder is one or more of T255 nickel powder, T123 nickel powder, T287 nickel powder, FNiT04 nickel powder, FNiT06 nickel powder and FNiT09 nickel powder.

[0012] Preferably, the Fisher particle size of the carbonyl nickel powder is 0.3 to 5 μm.

[0013] Further, the purity of the aluminum powder is greater than 99.0%, and the particle size is not higher than 150 μm.

[0014] Preferably, the particle size of the aluminum powder is in the range of 45-150 μm.

[0015] Further, the mixing is three-dimensional mixing or V-type mixing. When the mixing is three-dimensional mixing, the mixing time is 1.5 to 3 hours. When the mixing is V-type mixing, the mixing time is 3 to 6 hours. Through three-dimensional mixing or V-type mixing, the mixing time of the aluminum powder and the nickel powder can be shortened, and the cleanliness requirement of the materials can be ensured.

[0016] The beneficial effects of the present application are:

[0017] The anode powder for enhancing the safety of sodium-nickel single battery provided by the application is laid on the bottom of the steel shell and in good contact with the bottom of the ceramic tube. In the instant of Na produced by sodium-nickel battery formation, the anode powder provides electron conduction and siphon effect, so that a small amount of sodium can be in contact with the bottom surface of the ceramic tube, effectively reducing the current density through the bottom surface of the ceramic tube. When the BMS of the battery pack fails to cause over-discharge of the battery cell, because the anode powder in contact with the bottom surface of the ceramic tube provides an electron conduction path, current concentration will not occur. When the ceramic tube is broken and a large amount of NaAlCl4 on the positive side flows to the negative side steel shell, when discharging, because the activity of aluminum powder is greater than that of Fe, the aluminum powder reacts first, thereby protecting the steel shell from corrosion. When the aluminum powder in the anode powder is consumed in large quantities, the remaining nickel powder has good electron conductivity, so that the failed battery cell remains low internal resistance and becomes a substantial wire. The failed battery cell does not need to be replaced, and the remaining battery cells can still work normally, with only a 2.58V loss in series voltage.

[0018] The anode powder of the application has simple composition, low cost and simple manufacturing process, and is easy to mass produce. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a schematic diagram of the anode powder for enhancing the safety of sodium-nickel single battery filled in the battery cell of the application.

[0020] REFERENCE NUMERALS

[0021] 1-anode powder, 2-steel shell, 3-positive electrode particles, 4-Na-β"-Al2O3 solid electrolyte separator, 5-sodium tetrachloroaluminate, 6-current collector. DETAILED DESCRIPTION

[0022] The application will be further described below in conjunction with specific embodiments, but the application is not limited to these specific embodiments. In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the related drawings. The preferred embodiments of the present application are shown in the drawings. However, the application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the application more thorough and comprehensive.

[0023] Those skilled in the art should recognize that the application encompasses all alternatives, improvements and equivalents that can be included within the scope of the claims. Unless otherwise defined, all technical and scientific terms used in the application have the same meaning as understood by those skilled in the art to which the application belongs.

[0024] Among them, the T series of carbonyl nickel powder of the application is produced by Canada INCO company, T represents series, and the number represents the grade; FNIT is the naming rule of carbonyl nickel powder stipulated in national standard GB / T 7160-2017, F represents powder, NI is the chemical symbol of nickel, and the number represents the apparent density. The carbonyl nickel powder in the application can be bought in the market.

[0025] The following specific embodiments are the preparation method of the anode powder for enhancing the safety of sodium-nickel single battery of the application.

[0026] Example 1

[0027] Take 12 kg of aluminum powder with a particle size of 200 mesh and 1 kg of T255 nickel powder, mix them with a V-type mixer for 4 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 1200 ppm.

[0028] Example 2

[0029] Take 10 kg of aluminum powder with a particle size of 325 mesh and 1 kg of T123 nickel powder, mix them with a three-dimensional mixer for 2 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 810 ppm.

[0030] Example 3

[0031] Take 8 kg of aluminum powder with a particle size of 300 mesh and 4 kg of T255 nickel powder, mix them with a V-type mixer for 5 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 680 ppm.

[0032] Example 4

[0033] Take 10 kg of aluminum powder with a particle size of 100 mesh and 2 kg of FNiT04 nickel powder, mix them with a three-dimensional mixer for 2.5 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 920 ppm.

[0034] Example 5

[0035] Take 10 kg of aluminum powder with a particle size of 120 mesh and 3 kg of FNiT06 nickel powder, mix them with a V-type mixer for 6 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 490 ppm.

[0036] Example 6

[0037] Take 10 kg of aluminum powder with a particle size of 170 mesh and 5 kg of FNiT09 nickel powder, mix them with a three-dimensional mixer for 1.5 h to obtain the anode powder of the application. The anode powder is tested by Karl Fischer method, and the water content is 750 ppm.

[0038] Figure 1The schematic diagram of filling the anode powder of the present application for enhancing the safety of sodium nickel monomer battery in the cell. In the present embodiment, Figure 1 The sodium nickel monomer battery in the present application comprises anode powder 1, steel shell 2, positive electrode particles 3, Na-β"-Al2O3 solid electrolyte separator 4, sodium tetrachloroaluminate 5 and current collector 6. Among them, the current collector 6 is located in the center of the sodium nickel monomer battery, the outer layer of the current collector 6 is the Na-β"-Al2O3 solid electrolyte separator 4, the positive electrode particles 3 are filled between the current collector 6 and the Na-β"-Al2O3 solid electrolyte separator 4, and the sodium tetrachloroaluminate 5 is laid on the surface of the positive electrode particles 3. The outermost layer of the sodium nickel battery is the steel shell 2. At the bottom of the sodium nickel monomer battery, a certain thickness of anode powder 1 is laid between the Na-β"-Al2O3 solid electrolyte separator 4 and the steel shell 2, and the anode powder 1 is in contact with the solid electrolyte separator 4.

[0039] In the present embodiment, the working principle of the anode powder for enhancing the safety of sodium nickel monomer battery: at the moment of sodium nickel battery formation just producing Na, the anode powder 1 plays the role of electron conduction and siphon, so that a small amount of sodium can contact with the Na-β"-Al2O3 solid electrolyte separator 4 (i.e. ceramic tube), effectively reducing the current density through the bottom surface of the Na-β"-Al2O3 solid electrolyte separator 4; when the BMS of the battery pack fails to cause the over-discharge of the cell, because there is anode powder in contact with the bottom surface of the Na-β"-Al2O3 solid electrolyte separator 4 to provide an electron conduction path, no current concentration will occur. When the Na-β"-Al2O3 solid electrolyte separator 4 breaks, a large amount of NaAlCl4 on the positive electrode side flows to the negative electrode side steel shell, and when discharging, because the activity of aluminum powder is greater than that of Fe, the aluminum powder reacts first, thereby protecting the steel shell from corrosion, and when the aluminum powder in the anode powder is consumed in large amount, the remaining nickel powder has good electron conductivity, so that the failed cell remains low internal resistance and becomes a substantial wire, the failed cell does not need to be replaced, and the remaining cells can still work normally.

[0040] The above specific embodiments are used to explain and illustrate the present application, rather than limit the present application, any modifications and changes made to the present application within the spirit and protection scope of the claims of the present application, fall within the protection scope of the present application.

Claims

1. An anode powder for enhancing the safety of sodium-nickel single battery, characterized in that: The anode powder is formed by uniformly mixing nickel powder and aluminum powder, wherein the mass ratio of aluminum powder to nickel powder in the anode powder is 1:1 to 12:

1. The anode powder is laid at a certain thickness at the bottom of the sodium-nickel single cell, between the Na-β"-Al2O3 solid electrolyte membrane and the steel shell.

2. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 1, characterized in that: The anode powder is tested by the Erwin Fischer method, and the water content is not greater than 1500 ppm.

3. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 1, characterized in that: The nickel powder is carbonyl nickel powder, and the Fisher particle size is less than 10 μm.

4. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 3, characterized in that: The carbonyl nickel powder is one or more of T255 nickel powder, T123 nickel powder, T287 nickel powder, FNiT04 nickel powder, FNiT06 nickel powder, and FNiT09 nickel powder.

5. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 3, characterized in that: The carbonyl nickel powder has a Fisher particle size of 0.3-5 μm.

6. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 1, characterized in that: The purity of the aluminum powder is greater than 99.0%, and the particle size is no greater than 150 μm.

7. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 6, characterized in that: The particle size of the aluminum powder is in the range of 45-150 μm.

8. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 1, characterized in that: The mixing is three-dimensional mixing or V-shaped mixing.

9. The anode powder for enhancing the safety of sodium-nickel single battery according to claim 8, characterized in that: When the mixing is three-dimensional mixing, the mixing time is 1.5 to 3 hours; when the mixing is V-shaped mixing, the mixing time is 3 to 6 hours.

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