WO2010069209A1

WO2010069209A1 - Iron electrode material with low self discharge

Info

Publication number: WO2010069209A1
Application number: PCT/CN2009/074716
Authority: WO
Inventors: 陶明大; 何秀能; 潘唯
Original assignee: 成都和能科技有限公司
Priority date: 2008-12-17
Filing date: 2009-10-30
Publication date: 2010-06-24
Also published as: CN101651208B; CN101651208A

Abstract

An iron electrode material with low self discharge, the iron electrode material is consisted of an active material and an additive, the active material is iron or iron compound which comprises one or more members selected from Fe₃O₄, Fe(OH)₂, Fe(OH)₃, Fe₂O₃, reduced iron powder and carbonyl iron powder; the additive comprises (1) indium or indium compound with a content of 0.02-0.15％ which comprises one or more members selected from In, In₂O₃, In₂(SO₄)₃, In(OH)₃and InCl₃, (2)tin or tin compound with a content of 2-8％which comprises one or more members selected from Sn, SnO, SnO₂, SnCl₂, SnCl₄and stannate, (3)bismuth or bismuth compound with a content of 1-7％ which comprises one or more members selected from Bi, Bi₂O₃ and Bi(NO₃)₃, and (4) graphite powders with a content of 5-10％.

Description

1氐 self-discharge iron electrode material

4氐 self-discharge iron electrode material

[1] Technical field

[2] The present invention relates to an iron electrode material, and more particularly to a low self-discharge iron electrode material for use in the manufacture of an environmentally friendly iron-nickel battery.

[3] Background Art

[4] The iron-nickel battery was invented by Edison in 1900. Between 1910 and 1960, iron-nickel batteries were widely used as traction power sources for traction locomotives. However, after 1960, research on iron-nickel batteries has been reduced, mainly because cadmium-nickel batteries have better performance than iron-nickel. With the continuous advancement of society, people's requirements for environmental protection are getting higher and higher. The cadmium-nickel batteries and lead-acid batteries that were heavily contaminated with heavy metals will be replaced by environmentally-friendly batteries. The iron-nickel battery just meets this. Claim.

[5] The iron-nickel battery is a green secondary battery, which is a negative electrode active material of iron or iron, nickel oxyhydroxide as a positive electrode active material, and a sodium hydroxide (potassium) aqueous solution as an electrolyte. According to the preparation process of the electrode, the iron-nickel battery is divided into two types: a bag type battery and a plate type battery. The bag battery is characterized by a long life, but lower specific energy, while the plate battery is just the opposite, the life is lower than the bag type, but the specific energy is higher. Compared with traditional lead-acid batteries and nickel-cadmium batteries, iron-nickel batteries have obvious advantages: (1) There is no pollution to the environment. The materials used in iron-nickel batteries do not contain toxic heavy metal elements such as mercury, lead and cadmium, and no toxic gases and water are produced during the production process. (2) Long life. The life of cadmium-nickel batteries is more than 500 times, the life of lead-acid batteries is more than 250 times, the life of bag-type iron-nickel batteries can reach 2000-4000 times, and the usage time can reach 10-25 years. (3) The theory is higher than the energy. The positive electrode of the iron-nickel battery is the same as the positive electrode of the cadmium-nickel battery and the nickel-hydrogen battery, but the theoretical capacity of the iron electrode is as high as 1280 mAh/g, which is 2.67 times the theoretical capacity of the cadmium electrode and 3.56 times the theoretical capacity of the hydrogen electrode. (4) The price is moderate. Of all the electrode materials, the price of iron is the cheapest. Compared with nickel-hydrogen batteries and lithium-ion batteries, iron-nickel batteries also have a very low price. Compared with lead-acid batteries, the price of iron-nickel batteries is slightly higher, but its long life can fully compensate for this higher price. However, there are still some problems in iron-nickel batteries, including: (1) The self-discharge of the battery is large, and the self-discharge rate of the electrode is about 50 after 28 days at 20 °C. % (2) Poor performance in high current discharge and low temperature discharge. (3) The battery is less efficient to charge. (4) The utilization rate of the active material of the iron electrode is low. Generally only 10-20%. This greatly limits the specific energy of the iron-nickel battery. These problems are caused by the iron electrode.

[6] Summary of the invention

[7] The object of the present invention is to solve the problem of large self-discharge of an iron electrode, and to provide a low self-discharge iron electrode material.

, the charged iron electrode is placed at 20 ° C for 28 days, the electrode

The self-discharge rate is less than 20%, and has the advantages of low cost and no pollution of heavy metals.

[8] The low self-discharging iron electrode material of the present invention is composed of an active material and an additive. The active material is a compound of iron or iron, including Fe ₃ 0 ₄ , Fe(OH) ₂ , Fe(OH) ₃ , Fe ₂ 0 ₃ ,

One or more of reduced iron powder, carbonyl iron powder; additives include: 1) a compound having a content of 0.02-0.15% of indium or indium, including In, ln ₂ 0 ₃ , In ₂ (S04) ₃ , In ( OH) ₃ , InCl ₃

One or more of the foregoing, 2) a compound having a content of 2-8% tin or tin, including one or more of Sn, SnO, SnO ₂ , SnCl ₂ , SnCl ₄ and stannate,

3) A compound having a content of 1-7% of ruthenium or osmium, including one or more of Bi, Bi ₂ 0 ₃ , Bi(N0 ₃ ) _{3 ,} and the like, 4) a graphite powder having a content of 5 to 10%. Since the iron compound directly purchased has a high impurity content and is inferior in activity, it is generally required to be prepared by itself. A method for preparing the active material Fe ₃ 0 ₄ is exemplified: (1) A ferrous sulfate solution having a density of 1.24 - 1.26 g/cm ³ is prepared using purified water and technical grade ferrous sulfate. (2) Prepare a sodium hydroxide solution with a density of 1.13 - 1.15 g/cm3 using purified water and industrial grade sodium hydroxide. (3) The ferrous sulfate solution is heated to 90-98 ° C, and sodium hydroxide is sprayed into the ferrous sulfate solution, and the air is blown into the solution. (4) After the addition of sodium hydroxide is completed, acetylene black having a ferrous sulfate content of 1-5% is added, and then the air is submerged. (5) The resulting slurry was filtered with a chemical fiber canvas, and the precipitate was washed with purified water to be free of sulfate. (6) After the precipitate is dried, it is reduced to 780-880 °C. (7) The reduced substance was pulverized to a 20-mesh sieve to obtain a desired iron electrode active material.

[9] The iron electrode of the present invention has an advantage in self-discharge as compared with a conventional iron electrode.

[10] BRIEF DESCRIPTION OF THE DRAWINGS

[11] Figure 1: Low self-discharge iron electrode and ordinary iron electrode material 0.2C (60mA/g) discharge curve at 20 °C.

[12] Specific implementation

[13] Example: The chemical composition of the high capacity iron electrode material of the present invention is: [14] The content of Fe ₃ 0 ₄ prepared according to the above formula is 82-90%, the content of In ₂ 0 ₃ is 0.05-0.07%, and the content of SnO is 3-

5%, the content of Bi ₂ 0 ₃ is 2-4%, and the content of graphite powder is 6-8%.

[15] The iron electrode was prepared: (1) Weigh a quantity of Fe ₃ 0 _4, Fe ₃ 0 ₄ in amounts of 0.05-0.07% of added In203, 3-5% of SnO, 2-4% of Bi ₂ 0 ₃

. 7-8% graphite powder. (2) Add a certain amount of 5-10% PVA binder, stir evenly, and apply the slurry to the anode current collector (the current collector is one of foamed nickel, foamed iron or steel strip) . (3) After the electrode is dried, the electrode is press-formed on a hydraulic press with a pressure of 24 MPa.

[16] Charge and discharge test of iron electrode: The iron electrode obtained above is used as the working electrode, the sintered nickel hydroxide electrode is used as the auxiliary electrode, and the capacity of the auxiliary electrode far exceeds the capacity of the iron electrode, so the auxiliary electrode can be used. As a reference electrode, the electrolytic solution was a 6 mol/L KOH solution containing 15 g/L of LiOH.H ₂ 0, and the separator was a polypropylene felt. The electrochemical performance test equipment is a domestic DC-5 battery performance tester. The activation system was first activated 6 times with 0.2 C and the ambient temperature was 25 °C. 0.2C

After activation, the charging current is 100 mA·g - ¹ , charging for 6 h, the discharge current is 6θ Γ Α ^ ^, and the discharge cut-off potential is 1.0 V. The sixth discharge capacity is the initial capacity Q _{Q of} the electrode. The self-discharge test method is: After charging the electrode as described above, at 20

After leaving 28 under the condition of °C, the battery was discharged under the same conditions, and the obtained capacity was 3⁄4. The self-discharge rate is calculated as: Self-discharge rate = (Oo-Qi) / Q ₀ .

[17] As can be seen from Figure 1, the iron electrode material of the present invention is left at 20 ° C for 28 days.

The self-discharge rate is less than 20%, and the self-discharge rate of ordinary iron electrode materials is about 50%.

Claims

Claim

[1] A low self-release iron electrode material characterized by:

The iron electrode material is composed of an active material and an additive. The component of the active material is a compound of iron or iron. Additives include: 1) a compound of indium or indium in a concentration of 0.02 - 0.15%,

2) a compound of tin or tin having a content of 2-8%, 3) a compound of cerium or lanthanum having a content of 1-7%,

4) Graphite powder with a content of 5-10%.

[2] The low self-release iron electrode material according to claim 1, wherein the active material may be Fe

₃ 0 ₄ , one or more of Fe(OH) ₂ , Fe(OH) ₃ , Fe ₂ 0 ₃ , reduced iron powder, and carbonyl iron powder.

[3] The low self-draw iron electrode material according to claim 1, wherein:

The compound of indium or indium includes one or more of In, ln ₂ O ₃ , In ₂ (S04) ₃ , In(OH) ₃ , InCl _{3 ,} and the like.

[4] The low self-release iron electrode material according to claim 1, wherein:

The tin or tin compound includes one or more of Sn, SnO, SnO ₂ , SnCl ₂ , SnC S stannate, and the like.

[5] The low self-discharging iron electrode material according to claim 1, wherein:

A compound of ruthenium or osmium, including one or more of Bi, Bi ₂ O ₃ , Bi(N0 ₃ ) ₃ and the like.

[6] The low self-release iron electrode material according to claim 1, wherein the electrolyte used is

A 6 mol/L aqueous solution of KOH was added with 15 g/L of LiOH.H ₂ 0.