WO2016034143A1 - Secondary battery negative electrode material - Google Patents

Abstract

A secondary battery negative electrode material. The material comprises a framework, a chelation/adsorption group and an active substance. The framework does not participate in electrochemical reaction, and only provides a carrier for the chelation/adsorption group; the chelation/adsorption group contains atoms such as N, S, P, O having lone pair electrons in outer electrons, and can form a chelated or chemical adsorption bond (represented by an iminodiacetic acid chelated group in the figure) with bivalent and polyvalent metals; the active substance is bivalent or polyvalent metal ions that can be reduced into lower valence states. During charging, the metal ions used as the active substance are reduced into a lower valence state or a metal elemental state; during discharging, the metal ions are reversely generated and form a chelated or chemical adsorption bond with the chelation/adsorption group. The negative electrode material can be used with a plurality of positive electrode materials to form a battery. The battery is expected to be applied to electric vehicles and large-scale energy storage projects due to low price and reliability.

Description

Secondary battery anode material Technical field

The invention belongs to the field of electrochemical energy storage, and in particular relates to a secondary battery anode material.

Background technique

The current demand for energy storage technology far exceeds any time in human history. Whether it is a new energy vehicle, or future wind energy, solar power station support, or urban smart grid peaking and valley filling, etc., a huge number of reliable energy storage technologies are needed.

At present, the commercial battery technology is mainly old, and the lead-acid battery with great damage to the environment, the emerging lithium-ion battery has achieved great success in portable equipment, but in the large-scale power or energy storage field, due to the price, Factors such as safety are constrained. Therefore, the development of a safe, inexpensive rechargeable battery is a very pressing issue.

In 1994, Wu Li of the Jeff Dahn Research Group in Canada published a paper on the use of VO ₂ as a negative electrode material LiMn ₂ O ₄ as a positive electrode material and an aqueous solution as an electrolyte in the journal Science, which pioneered the water-based lithium-ion battery. However, due to the long-term solution to the stability problem of lithium-embedded anode materials, after nearly 20 years of development, such batteries are still unable to obtain practical applications.

In 2009, Chinese researcher Jing Yan reported in the patent 201010154104.X and 2011 in the journal of power sources 2012.05.063 a LiMn ₂ O ₄ cathode material, an aqueous solution as an electrolyte, and an aqueous solution. The zinc ion is used as a negative electrode active material battery system (lithium-zinc battery). This system completely solves the problem of negative electrode stability of water-based lithium ion batteries, but the change of the basic mechanism makes the battery no longer known as water lithium ion. The battery has become a brand new battery system, which is called Yan's battery for the time being. Due to the use of conventional Zn/Zn ²⁺ electrodes, the battery inevitably faces the problem of zinc dendrite, making battery design very difficult.

The technology described herein combines the advantages of a water-based lithium battery with the aforementioned lithium-zinc battery, using a chelating/adsorbing group to "fix" the metal ion to redox it in situ in the negative electrode material, apparently, If the material is combined with a lithium-embedded positive electrode such as LiMn ₂ O ₄ , the macroscopic performance and battery design will be similar to that of the water-based lithium ion battery, and the chelate/adsorption type negative electrode can ensure the stability of the material and solve the Zn2+ solution. The problem of zinc dendrite during / Zn electrode charging and discharging.

The material's working mechanism is unprecedented and will revolutionize battery technology.

Summary of the invention

The present invention is directed to providing a secondary battery negative electrode material.

The negative electrode material proposed by the invention has an unprecedented charge and discharge mechanism, and the metal/metal ion electrode has been widely studied in the past, for example, lithium metal as a negative electrode in a lithium battery and zinc as a negative electrode in a zinc-bromine battery. The electrode has an almost infinite lifetime in principle, but due to the dendritic problem of metal/metal ions during charging, such electrodes, although having very good electrochemical properties, are difficult to find in the battery industry.

The invention provides a secondary battery anode material, which can completely overcome the dendrite problem of metal/metal ions during charging.

The technical solution of the present invention is as follows:

A secondary battery anode material mainly composed of a skeleton, a chelating/adsorbing group, and a "fixed" active material, a divalent or polyvalent metal ion, the skeleton being an organic polymer, and the skeleton passing a chemical bond that immobilizes the chelating/adsorbing group on a backbone, the chelating/adsorbing group being a group comprising atoms of O, N, P, etc. having an outer electron having a lone pair of electrons, said hydrazine The binding/adsorbing group may form an ionic bond or a coordinate bond with the divalent or polyvalent metal ion of the active material.

The secondary battery negative electrode material skeleton provided by the present invention does not participate in the reaction itself, but serves as a carrier. The chelate/adsorbing group is chemically bonded to the carrier backbone, and the chelate/adsorbing group itself does not participate in the electrochemical redox reaction, but is linked to the active metal ion by a chelate bond or a chemisorption bond. The metal ion as the active material is immobilized on the chelating group in the form of chelation or chemisorption, and the electron can be reduced to a lower-valent state or a zero-valent state in situ.

In the above secondary battery negative electrode material, the organic polymer may be polystyrene, polyvinyl chloride, polymethacrylic acid, polyacrylic acid, polyethylene or polypropylene.

In the above secondary battery negative electrode material, the chelating/adsorbing group may be an iminodiacetic acid group, a carboxylic acid group or a phosphoric acid group.

In the above secondary battery negative electrode material, the active material divalent or polyvalent metal ion may be a metal ion having an electrochemical redox potential of -1.2 V (relative to a hydrogen standard electrode potential) in an aqueous solution.

In the above secondary battery negative electrode material, the active material divalent or polyvalent metal ion may be Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Pb ²⁺ , Zn ²⁺ , Mn ²⁺ , Ni ²⁺ or Transition metal ions such as V ³⁺ .

The secondary battery negative electrode material of the present invention can be paired with a lithium intercalation compound such as LiMn ₂ O ₄ or LiFePO ₄ or a sodium ion intercalation compound positive electrode material such as NaMnxOy to form a secondary battery excellent in performance, and thus the secondary battery negative electrode material of the present invention Has a very far-reaching significance.

DRAWINGS

1 is a schematic view showing the basic working principle of the iminodiacetic acid group-zinc anode material of the present invention, showing a typical skeleton-iminodiacetic acid chelating group-zinc ion type compound charging and discharging process working diagram, The chelated zinc ions are reduced to metallic zinc during charging. Since the anode material of the present invention can be charged and discharged in an aqueous solution, it can also be combined with many other types of cathode materials to form a rechargeable secondary battery.

FIG. 2 is a schematic diagram of the working principle of the battery according to Embodiment 1 of the present invention.

FIG. 3 is a schematic diagram of a working principle of a battery discharged according to Embodiment 1 of the present invention.

4 is a structural view of a battery according to an embodiment of the present invention.

5 is a graph showing the first voltage-time charge and discharge curves of a LiMn ₂ O ₄ /R-iminodiacetic acid group-Zn battery according to Example 1 of the present invention.

Figure 6 is a graph showing the cycle performance of a LiMn ₂ O ₄ /R-iminodiacetic acid group-Zn battery according to Example 1 of the present invention.

Fig. 7 is a structural view of an electrode material of the present invention having a polymer of acrylic acid (top)/methacrylic acid (lower image) as a skeleton, a chelate/adsorbing group being a carboxyl group, and an active metal ion being a zinc ion.

8 is a graph showing charge and discharge voltage-time curves of a LiMn ₂ O ₄ /R-carboxy group-Zn battery of Example 3.

9 is a cycle performance diagram of a LiMn ₂ O ₄ /R-carboxy group-Zn battery of Example 3.

Fig. 10 is a graph showing charge and discharge curves of the battery of Example 4.

Figure 11 is a schematic view of the negative electrode in Example 5, wherein the active material is zinc, the chelate adsorption group is an aminophosphonic acid group, the upper graph shows the state of unchelated zinc ions, and the lower graph shows the state of having chelated zinc ions.

12 is a graph showing a charge-discharge voltage-time curve of a LiMn ₂ O ₄ /R-aminophosphonic acid group-Zn battery of Example 5.

detailed description

In the negative electrode material of the present invention, during charging (see Fig. 2), the divalent or polyvalent metal obtains electrons which are reduced to a lower valence state, or a zero valent metal state. The discharge process (see Fig. 3) is the reverse process of charging, and the metal as the active material is again changed to the chelate/adsorption state.

For example, if the lithium ion intercalation type compound Li (HOST) is used as the battery positive electrode material and the Zn ²⁺ ion is used as the metal active material described in the present report, the reaction of the positive electrode during charging is:

Li(HOST)-e ^- →Li ⁺ +(HOST) ^-

The reaction of the negative electrode is:

RC-Zn ²⁺ +2e ^- →RC-Zn, (wherein R represents a skeleton and C represents a chelating/adsorbing group)

Taking LiMn ₂ O ₄ /RC-Zn battery as an example (see Fig. 4), LiMn ₂ O ₄ is a positive electrode active material, and the electrolyte is a 1 mol/L Li ₂ SO ₄ battery, which is charged in LiMn ₂ O ₄ . The Li ⁺ ions are removed from the spinel lattice while a trivalent manganese in the crystal lattice is oxidized to tetravalent and an electron is output. LiMn ₂ O ₄ lithium ions coming out since the shape becomes Li _1-x Mn ₂ O _4, while chelated zinc ions RC-Zn material is reduced and deposited to obtain an electron in an external circuit from the anode material. The positive electrode reacts to LiMn ₂ O ₄ -xe-→Li ⁺ +Li _1-x Mn ₂ O ₄ during charging, and the negative electrode reacts with RC-Zn ²⁺ +2e-→RC-Zn. The discharge process is the reverse process of the charging process, that is, the oxidation of the zero-valent zinc of the negative electrode and re-conversion into chelated zinc ions, and the positive electrode obtains electrons and is inserted into Li _1-x Mn ₂ O ₄ with lithium ions. Note: At present, in the lithium battery industry, almost all cathode materials are doped, coated and modified. For example, LiMn ₂ O ₄ has not been able to represent the general formula of "manganese manganate" which is currently widely used. The general formula of the material should be strictly as described in the general formula of the spinel structure compound provided by the present invention. However, the chemical formula expression of the material is complicated by the means of doping, inclusion modification, etc., so the LiMn ₂ O ₄ described in the present invention, in terms of its technical essence, should be broadly included after various modifications. The positive electrode material of the formula of the spinel structure provided by the present invention. Further, the chemical formula of a material such as LiFePO ₄ described in the present invention should also include a material of a general formula which has been modified to conform to a layered structure compound, a spinel structure compound or an olivine structure compound.

The main advantages of the invention are:

1. The negative electrode material provided by the present invention solves the dendrite problem that is difficult to solve when the metal/metal ion electrode is used as a battery negative electrode.

2. The negative electrode material provided by the invention is environmentally friendly and inexpensive.

3. The battery produced by the negative electrode material provided by the present invention is excellent in performance.

The invention is further illustrated below in conjunction with specific embodiments. It is to be understood that the examples are not intended to limit the scope of the invention. The experimental methods in the following examples which do not specify the specific conditions are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. All percentages, ratios, ratios, or parts are by mass unless otherwise stated.

The unit of mass by volume in the present invention is well known to those skilled in the art and, for example, refers to the mass of the solute in a 100 ml solution.

Unless otherwise defined, all professional and scientific terms used in the specification have the same meaning as those skilled in the art. In addition, any methods and materials similar or equivalent to those described may be employed in the methods of the invention. The preferred embodiments and materials described in the specification are for illustrative purposes only, and Embodiments 1, 2, 3 and 4 are capable of demonstrating the correctness of the principles of the invention to those skilled in the art.

Example 1 Preparation of Secondary Battery

1. Preparation of positive electrode sheet: LiMn ₂ O ₄ is used as positive electrode active material, according to positive electrode active material 90%: conductive carbon black 6%: adhesive SBR (styrene-butadiene rubber latex) 2%: thickener CMC (carboxyl Base cellulose sodium) 2% ratio, first mix CMC with a certain amount of water, then add active material and conductive carbon black, stir for 2 hours, and finally add SBR for 10 minutes to obtain a positive electrode slurry. The positive electrode current collector was a 150 mesh SUS304 stainless steel mesh, and the positive electrode slurry was uniformly coated on the positive electrode current collector, and cut into a size of 10 mm×10 mm and a weight of 50 mg. Dry at 120 ° C for 12 hours to form a positive electrode sheet.

2. Preparation of negative electrode active material: 1Kg of commercially available iminodiacetic acid chelating resin (PUROLITE S930, a crosslinked polystyrene-based skeleton, an iminodiacetic acid group as a reactive group, and a special large The chelating resin of the pore structure is placed in 10 L of 20% by mass sodium hydroxide solution for 24 hours, and then washed with deionized water to pH=6-9. It is dried at 100 ° C, and the ball mill is pulverized to over 400 mesh to obtain Anode material precursor.

The precursor is mixed with a saturated zinc sulfate solution, wherein the mass ratio of the precursor to zinc sulfate is 1:3, the pH value is controlled between 2-6, and the mixture is stirred for 3 hours, filtered, washed and dried to obtain the second time of the present invention. Battery anode material.

3. Preparation of secondary battery: The negative electrode active material is mixed with tin dioxide, conductive carbon black and zinc powder by a ball mill at a mass ratio of 7:0.5:0.5:2, and pressed into a sheet shape, the size is 10 mm×10 mm, and the mass is 200 mg. The battery anode current collector is a zinc foil with a thickness of 0.05 mm. The electrolytic solution was an aqueous solution containing a concentration of 1 mol/L of lithium sulfate, and the pH was adjusted to 4. The positive electrode sheet and the negative electrode sheet were assembled into a battery, and the separator was separated by a separator, and the separator was a nonwoven fabric separator.

The battery positive electrode active material has a mass of about 45 mg, a negative electrode active material of about 140 mg, and a theoretical capacity of about 5 mAh. The battery structure is as shown in FIG. A 1 ml electrolyte was injected and the charge and discharge tests were performed after standing for 12 hours. The charge and discharge voltage range is 1.4-2.1V. The battery charge-discharge voltage-time curve is shown in Figure 5. The battery demonstrates excellent cycle performance, as shown in Figure 6.

Considering that the same broad class of chelating resin backbones of the same broad class using the iminodiacetic acid group as the reactive group will vary slightly, in the present embodiment, the synthetic product is similar to the skeleton-iminodiacetic acid. The material of zinc should be regarded as the same technology as this embodiment.

Example 2

A battery was fabricated in the same manner as in Example 1, except that the negative electrode active material was prepared as follows:

100 g of sodium polyacrylate (molecular weight 10000) was placed in 1 L of deionized water, 400 g of zinc sulfate was dissolved in 1 L of water, and then poured into a mixture of the above sodium polyacrylate and water, and the solution was mixed for 10 hours, washed and filtered. Then, it is mixed with the carbon black conductive agent at a ratio of 8:1:1, and pressed into a pole piece having the same mass per unit area as the positive electrode, and the negative electrode is attached to the zinc foil current collector.

The positive electrode of the battery was the lithium manganate pole piece described in Example 1, the positive and negative electrode areas were the same, the positive and negative electrode mass ratio was 1:1, and the electrolyte solution was a neutral lithium sulfate solution having a pH of 7.

The structure of the material prepared by the method is shown in Fig. 7 (top), the chelating/adsorbing group of the material is a carboxyl group, and the two carboxyl groups attached to the carrier form an ionic bond with the zinc ion and fix the zinc ion. The charge and discharge performance is similar to that described in Example 1 in which the iminodiacetic acid group is a chelating group, but the quality of the negative electrode material is reduced, thereby increasing the energy density of the battery.

The charge and discharge curve obtained by the battery is shown in Fig. 10.

Example 3

A battery was fabricated in the same manner as in Example 1, except that the negative electrode active material was prepared as follows:

100 g of polyacrylic acid weak acid adsorption resin (DIAION WK10, a methacrylic type weakly acidic cation exchange resin, the structure shown in Figure 7) was pulverized to a 400 mesh screen, and 400 g of zinc sulfate was dissolved in 1 L of water. Pour the above resin powder, mix the solution for 10 hours, wash and filter, and then mix it with carbon black conductive agent, adhesive PTFE powder to a ratio of 8:1:1, and press into a sheet. Paste on the zinc foil current collector.

The battery positive electrode used the lithium manganate pole piece described in Example 1, the positive and negative electrode pieces were the same size, the active material mass ratio was 1:1, and the electrolyte solution was a neutral lithium sulfate solution of pH 7.

The structure of the material prepared by the method is shown in Fig. 7. The chelating/adsorbing group of the material is a carboxyl group, and the two carboxyl groups attached to the carrier form an ionic bond with the zinc ion and fix the zinc ion, charge and discharge. The properties are similar to those described in Example 1 in which the iminodiacetic acid group is a chelating group, but the quality of the negative electrode material is reduced.

The charge and discharge curve obtained by the battery is shown in Fig. 8, and the cycle number-capacity chart is shown in Fig. 9.

Example 4

The positive electrode was mixed in such a manner that lithium manganate: conductive carbon black: PTFE had a mass ratio of 8:1:1, and was pressed into a sheet having a size of 60 mm×60 mm, and the mass was 3 g. The positive current collector was a graphite sheet having a thickness of 500 μm.

The preparation method of the negative electrode is as follows:

100 g of polyacrylic acid weak acid adsorption resin (DIAION WK10, a methacrylic type weakly acidic cation exchange resin adsorption group structure shown in Figure 7) was pulverized to a screen of 800 mesh, 400 g of lead acetate dissolved in 1 L of water Pour the resin powder, mix the solution for 10 hours, filter and wash, then mix the resin with carbon black conductive agent, PTFE powder at a mass ratio of 6.5:3:0.5, and compact it into 60mm×60mm (thickness about 0.7mm), quality It is a 4g pole piece attached to a 100um thick lead foil.

The electrolyte is 1mol/L lithium acetate solution

The positive electrode tab and the negative electrode tab were separated by 70 mm X 70 mm filter paper, and 4 ml of electrolyte was injected to form a battery. The structure is shown in FIG. 4 .

The battery was subjected to 50 mA constant current charge and discharge to obtain a charge and discharge curve as shown in Fig. 10, and the battery exhibited very good reversibility.

Example 5

The positive electrode was mixed in such a manner that lithium manganate: conductive carbon black: PTFE had a mass ratio of 8:1:1, and was pressed into a sheet having a size of 60 mm×60 mm, and the mass was 3 g. The positive current collector was a graphite sheet having a thickness of 500 μm.

The preparation method of the negative electrode is as follows:

Take 100 grams of aminophosphonic acid chelating resin (Bayer TP260, adsorption group structure shown in Figure 11, the upper picture is unadsorbed, the figure below is the state of adsorption of zinc ions) pulverized to 800 mesh screen, 400 grams of zinc acetate Dissolved in 1L of water, poured into resin powder, mixed with solution for 10 hours, filtered and washed, then The resin and the carbon black conductive agent, the PTFE powder were mixed at a mass ratio of 6.5:3:0.5, rolled into a 60 mm X 60 mm (thickness of about 0.7 mm), and a mass of 9 g of the pole piece was attached to a 100 um thick zinc foil.

The electrolyte is 1mol/L lithium sulfate solution

The positive electrode tab and the negative electrode tab were separated by 70 mm X 70 mm filter paper, and 10 ml of electrolyte was injected to form a battery. The structure is shown in FIG. 4 .

The battery was subjected to 50 mA constant current charge and discharge to obtain a charge and discharge curve as shown in Fig. 12, and the battery exhibited very good reversibility.

Example 6 Preparation of Secondary Battery

1. Preparation of positive electrode sheet: LiMn ₂ O ₄ is used as positive electrode active material, according to positive electrode active material 90%: conductive carbon black 6%: adhesive SBR (styrene-butadiene rubber latex) 2%: thickener CMC (carboxyl Base cellulose sodium) 2% ratio, first mix CMC with a certain amount of water, then add active material and conductive carbon black, stir for 2 hours, and finally add SBR for 10 minutes to obtain a positive electrode slurry. The positive electrode current collector was a 150 mesh SUS304 stainless steel mesh, and the positive electrode slurry was uniformly coated on the positive electrode current collector to have a coating density of about 500 g/m ² . Dry at 120 ° C for 12 hours to form a positive electrode sheet.

2. Preparation of negative active material: chloromethylated crosslinked polystyrene spheres (chlorine spheres) and ammonia were aminated at a temperature of 50 ° C for 12 hours using dimethylformamide (DMF) as solvent. The amount of ammonia was The chlorine content of the chloromethylated crosslinked polystyrene sphere is 4 times. After the reaction, the mother liquor is filtered off and the solid product is washed with ethanol. The solid substance is added in 1 part of the solid content while cooling in a cold water bath, and stirring is continued, and 3 is slowly added. Part by weight of chloroacetic acid, followed by continuous addition of sodium hydroxide solution and maintaining the pH of the solution above 10. The reaction temperature was less than 70 ° C for 20 hours. After the reaction is completed, the solid matter is filtered, washed and dried for use. The dried reactant was placed in a 20% aqueous sodium hydroxide solution for 5 hours, filtered, and washed until the washing liquid was neutral to obtain a negative electrode material precursor.

The precursor is mixed with a saturated zinc sulfate solution, wherein the mass ratio of the precursor to zinc sulfate is 1:3, and the mixing and stirring time is 3 hours, and the secondary battery negative electrode material of the present invention is obtained by filtration, washing and drying.

3. Preparation of secondary battery: the negative electrode active material is mixed with tin dioxide, conductive carbon black and zinc powder in a ratio of 7:0.5:0.5:2, and a certain proportion of deionized water is added to form a black slurry. The coating density was 1200 g/m ² on the battery anode current collector. The battery negative current collector is a copper tin-plated foil, wherein the copper foil has a thickness of 0.02 mm and the tin plating layer has a thickness of 0.005 mm to 0.01 mm. The electrolytic solution was an aqueous solution containing a concentration of 1 mol/L of lithium sulfate, and the pH was adjusted to 4. The positive electrode sheet and the negative electrode sheet were assembled into a battery, and the separator was separated by a separator, and the separator was a nonwoven fabric separator.

The battery positive electrode active material has a mass of about 50 mg, a negative electrode active material of about 150 mg, and a theoretical capacity of about 5 mAh. The battery structure is as shown in FIG. The electrolyte was injected and the charging and discharging tests were carried out after standing for 12 hours. The charge and discharge voltage range is 1.4-2.1V. The battery first charge and discharge voltage-time curve is as shown in Fig. 5 of the first embodiment. The battery exhibited excellent cycle performance as shown in Figure 6 of Example 1.

It can be seen that the negative electrode material of the present invention is not a single material but a combination of materials. The microstructure of the material obtained by the combination of different skeletons and chelating/adsorbing functional groups is different, but the principle is similar to that of the battery, and it can be seen that the skeleton or the chelating/adsorbing group is simply replaced, or as described in Examples 1, 3 and 4. It is within the scope of the invention to make obvious modifications to the chelating group.

Claims (6)

1. A secondary battery negative electrode material characterized in that it is mainly composed of a skeleton, a kneading/adsorbing group and a "fixed" active material of a divalent or polyvalent metal ion, and the skeleton is an organic polymer. The scaffold is immobilized on the skeleton by a chemical bond, and the chelate/adsorbing group is a group containing O, N, and P atoms having a lone pair of electrons in the outer layer. The chelating/adsorbing group and the active material divalent or polyvalent metal ion form an ionic bond or a coordinate bond.
2. The secondary battery negative electrode material according to claim 1, wherein the organic polymer is polystyrene, polyvinyl chloride, polymethacrylic acid, polyacrylic acid, polyethylene or polypropylene;
3. The secondary battery negative electrode material according to claim 1, wherein the chelating/adsorbing group is an iminodiacetic acid group, a carboxylic acid group or a phosphoric acid group.
4. The secondary battery negative electrode material according to claim 1, wherein the active material divalent or polyvalent metal ion is a metal ion having an electrochemical redox potential of -1.2 V or more in an aqueous solution.
5. The secondary battery negative electrode material according to claim 4, wherein the active material divalent or polyvalent metal ions are Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Pb ²⁺ , Zn ²⁺ , Mn ²⁺ , Ni ²⁺ or V ³⁺ transition metal ion.
6. The secondary battery negative electrode material according to claim 1 for use in the preparation of a secondary battery.

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