JP2019121601A - Lithium ion battery electrode material firing pot and protective layer of the same - Google Patents

Abstract

The present invention provides a protective layer of a sagger for firing a lithium ion battery electrode material, which has high corrosion resistance, high adhesion, and is hardly peeled off, and a lithium ion battery electrode capable of extending the service life of the sagger. It is an object to provide a sagger for firing material. In order to solve the above-mentioned problems, the present invention provides a protective layer comprising LiAlSiO4 having a negative coefficient of thermal expansion, and one or both of a metal oxide and a metal salt having a positive coefficient of thermal expansion. The present invention provides a sagger for firing electrode material for a lithium ion battery, and a protective layer of the sagger for firing electrode material for a lithium ion battery, comprising: [Selection diagram] Fig. 1

Description

  The present invention relates to a crucible for firing lithium ion battery electrode materials, and a protective layer of the crucible.

  In recent years, with the development of technology, lithium ion secondary battery performance can be improved, and is widely applied in fields such as mobile phones, laptop computers, electric vehicles, and energy storage. The lithium ion secondary battery is mainly composed of a positive electrode material, a negative electrode material, an electrolytic solution and a separator. Among them, as positive electrode materials, there are commercially available products such as lithium iron phosphate, lithium cobaltate, lithium nickel cobalt manganate (three-component system), and nickel system. Materials such as graphite and lithium titanate are employed as the negative electrode material. The performance of the positive and negative electrode materials determines the battery capacity, energy density, cycle characteristics, and the like. The production process of the positive electrode material will be briefly described: a precursor of the positive electrode material, ie, cobalt oxide or hydroxide (eg, cobalt hydroxide, nickel hydroxide cobalt manganese, nickel cobalt hydroxide, nickel hydroxide cobalt aluminum, water Mix nickel-manganese oxide etc., lithium source (eg lithium carbonate, lithium hydroxide etc.) in a fixed proportion, put in a fixed amount in a ceramic bowl and then bake for a long time at high temperature 800-1100 ° C Do the conclusion. When firing lithium cobaltate, lithium iron phosphate, and ternary positive electrode materials (molar ratio of nickel cobalt manganese is 1: 1: 1, 5: 2: 3, 6: 2: 2), it is usually excessive. Lithium carbonate is used as a lithium source, but lithium carbonate is in a molten state at high temperature and easily penetrates to the surface layer of mortar, and chemically reacts with aluminum oxide, silicon oxide, etc. which are main components of mortar, and the product It was also confirmed that it adheres to the surface of a mortar; and nickel nickel manganese manganate (for example, the ratio of nickel cobalt manganese is 8: 1: 1), which is a new high capacity ternary positive electrode material of high nickel type. ) Or an excess of lithium hydroxide is usually used as a lithium source when calcining lithium nickel cobalt lithium aluminum oxide. Lithium hydroxide is mainly a dihydrate, and even when anhydrous lithium hydroxide is used, water is lost at high temperatures, corrosion by a strong alkali is very high, and irreversible deterioration to a mortar is caused, The life span of the

  Patent Document 1 proposes the use of one or more of zirconia, alumina, magnesia and the like as a coating material for the same purpose. While the above materials are highly corrosion resistant, zirconia is expensive, alumina can react with lithium, magnesium-containing compounds such as magnesia have higher coefficients of thermal expansion, and any of the above mentioned materials Since the material is a thermally expandable material, the coating film tends to be cracked when used repeatedly, and the adhesion is reduced. Moreover, the life evaluation method described in Patent Document 1 was based on the case where it could not be used. The meaning of "cannot be used" is unclear as to whether it is cracked, peeled off or broken, so it is ambiguous to use it as a criterion.

In addition, as a material for forming a corrosion resistant coating, alumina is mentioned in many documents. Alumina reacts with lithium source lithium carbonate and lithium hydroxide at high temperature to form LiAlO ₂ . By suppressing the further reaction between alumina and the raw material of the positive electrode material by the formation of LiAlO ₂ , the corrosion resistance derived from lithium is suppressed, and the purpose of corrosion resistance can be achieved. However, since the thermal expansion coefficient of LiAlO ₂ is considerably higher than the thermal expansion coefficient of the mortar base, a film in which only alumina is used is likely to be peeled off from the mortar base during temperature rise and cooling of repeated firing, The corrosion effect is reduced.

  Further, in Patent Document 2, a corrosion resistant coating layer is pressed on the surface of a mortar base made of cordierite, mullite or the like using a secondary pressing method, and the coating layer is mainly made of zirconia and sudojumen. Do. Although these materials did not react with lithium carbonate as a raw material for firing the positive electrode material, they were able to improve the corrosion resistance and extend the service life to some extent, but both zirconia and spodumene have positive thermal expansion coefficients Even if it is a material, even if the mixture ratio is adjusted, the difference between the thermal expansion constant between the coating film and the base material is large. The protective layer easily peels off. Furthermore, the secondary pressing process used in Patent Document 2 is complicated, the pressed film is nonuniform, and there is a possibility that a crack may occur due to the reduction in strength on the arc surface of the bottom or side of the mortar. .

CN103884190 published gazette

CN103311498 published gazette

  In view of the above-mentioned problems of the prior art, the present invention has a corrosion-resistant, high-adhesiveness, hard-to-peel protective layer (coating film), and a lithium ion battery electrode material firing mortar and a hard-to-peel protective layer. Intended to be provided.

In order to solve the said subject, 1st invention of this invention provides the mortar for lithium ion battery electrode material baking.
(1) A main body (substrate), and a protective layer covering at least the bottom of the inner surface of the main body;
Wherein the protective layer comprises LiAlSiO ₄ and one or both of a metal oxide and a metal acid salt having a positive coefficient of thermal expansion. A pot for firing battery electrode materials. (2) The ratio of the thermal expansion coefficient of a protective layer and the thermal expansion coefficient of a mortar body is 1: 1-2: 1, The mortar for lithium ion battery electrode material baking as described in (1) characterized by the above-mentioned.
(3) The metal oxide and the metal salt are selected from MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ , LiAlSi ₂ O ₆ (1) or (2), which is one or two or more substances.
(4) The mortar for firing lithium ion battery electrode material according to any one of (1) to (3), wherein the main body is formed of cordierite, mullite or a mixture thereof. The mortar body can adopt the material which has the above-mentioned cordierite, mullite, or their mixture as a main component, but may be constituted from other materials.

  Furthermore, for the mortar protective layer of the present invention to be effective, at least the bottom of the inner surface of the body should be coated, and in order to better prevent corrosion to the main body, covering the entire inner surface of the main body preferable. Moreover, the inner surface of the mortar body of this invention means the surface which mounts the raw material used for baking of electrode material.

  The mortar for firing a lithium ion battery electrode material of the present invention is used for firing an electrode material in a lithium ion secondary battery. The electrode materials include, but are not limited to, the following substances: metal oxide lithium salts having a layered structure, such as lithium cobaltate, nickel cobalt manganese ternary material, lithium rich manganese material, etc .; Those having an olivine structure, such as lithium iron phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, etc .; lithium manganate having spinel structure, nickel manganese binary material, etc .; titanium as negative electrode material Lithium acid.

A second invention of the present invention provides a protective layer for a lithium ion battery electrode material firing mortar.
(5) The protective layer is characterized by including a base component which is LiAlSiO ₄ and a filler which is positive in thermal expansion coefficient and which is either one or both of a metal oxide and a metal salt. Protective layer of baking pot for ion battery electrode material.

(6) The ratio of the thermal expansion coefficient of the protective layer to the thermal expansion coefficient of the mortar body is from 1: 1 to 2: 1. Protective layer.
(7) The filler is selected from one or more of MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ , LiAlSi ₂ O ₆ (6) or (7), wherein the protective layer for firing of the lithium ion battery electrode material according to (6) or (7).

Since the mortar of the present invention adopts the protective layer of the above-mentioned component, when the raw material of the electrode material of the lithium battery is placed on the mortar and sintered repeatedly at high temperature, the thermal expansion coefficient of the protective layer is Since the thermal expansion constant of the main body is close to that of the main body, the adhesion of the protective layer to the surface of the mortar is good and it becomes difficult to peel off. In general, if the thermal expansion constant of the coating film and the base material is not appropriate, the adhesion between the thin film and the base material becomes unstable and it is easy to peel off when firing repeatedly at high temperature. Since either or both of the metal oxide and the metal salt used as the protective layer component of the present invention have a positive thermal expansion coefficient, the thermal expansion coefficient is constant with LiAlSiO ₄ having a negative thermal expansion coefficient. The thermal expansion coefficient of the protective layer is still positive, but by approaching the positive thermal expansion coefficient of the mortar body, it can be realized that the protective layer is less likely to be peeled off from the mortar body.

In addition, since the mortar of the present invention is not easily corroded by the material placed in the mortar during firing, the service life is extended and the manufacturing cost of the electrode material can be reduced. That is, LiAlSiO _{4 in} the protective layer of the present invention does not react chemically with the mortar body, nor with the electrode material (positive electrode material or negative electrode material) or the raw material of the electrode material, It was possible to suppress the reaction with and to suppress the corrosion from the material to be put on to the mortar.

FIG. 1 is a cross-sectional view showing an example of a mortar according to the present invention. FIG. 2 is a partially enlarged view showing a cross section of the mortar base of FIG. Is an XRD graph of the mortar protective layer according to Example 1.

Hereinafter, the present invention will be described in detail.
The mortar 1 shown in FIG. 1 comprises a body 2 and a protective layer 3 coated on the inner surface 21 of the body 2. When producing the mortar, the raw material of the electrode material is placed on the inner surface 21 of the main body 2. Further, in the present embodiment, the protective layer 3 covers the entire surface of the inner surface 21 composed of the bottom portion 211 of the inner surface 21 of the main body 2 and the wall surface 212. From the partially enlarged view of the bottom portion 211 as shown in FIG. 2, the protective layer 3 is in close contact with the bottom portion 211 of the inner surface 21.

  In the manufacturing process of the lithium battery electrode material, the caustic pot 1 is gradually corroded due to the positive electrode material and lithium carbonate and lithium hydroxide which are firing raw materials of the negative electrode material, alumina and the oxide of the main body material of the caulder 1 Chemical reaction occurs with silicon under high temperature conditions to form a new substance. This product differs from the composition of mortar 1 and the thermal expansion coefficient also has a large difference. When the mortar 1 is repeatedly used, this product gradually peels off from the main body 2 of the mortar 1, so that the life of the mortar 1 is greatly reduced and the product is a battery material sintered as a foreign substance. May be mixed in the

  Therefore, the present inventors provide the protective layer 3 having a specific composition on the surface of the mortar 1, thereby using lithium carbonate, which is used for firing the positive electrode material or the negative electrode material such as lithium titanate, etc. Lithium carbonate, lithium hydroxide and the like can effectively suppress the corrosion to the mortar 1 and the service life of the mortar 1 can be extended by the lithium etc. blocking the contact with the mortar 1 material.

Specifically, LiAlSiO ₄ used does not react chemically with the main body 2 of the ceramic 1 in the protective layer 3 of the ceramic 1 for firing a lithium ion battery electrode material of the present invention, and an electrode material or an electrode material Since the material which does not react chemically with the raw material of the above, it is effective that the material on which the mortar 1 is put during sintering is not easily corroded. Furthermore, LiAlSiO ₄ is in a molten state at 1200 ° C. to 1300 ° C., and fully penetrates the surface layer of mortar 1 through the pores of the surface of mortar 1. In addition, the protective layer 3 of the firing pot 1 for firing an electrode material for a lithium ion battery according to the present invention further extends the working life of the pot 1 by further adding a filler having corrosion resistance among LiAlSiO _4. can do.

  The present inventors need to consider not only the reactivity to the positive electrode material and the negative electrode material but also the thermal expansion coefficient of the components contained in the protective layer 3 of the mortar 1. The coating layer is likely to peel off the surface of the mortar 1 from the surface of the mortar 1, and the function of protecting the mortar 1 can not be obtained. It mixes in a positive electrode material material, and a positive electrode material material will be contaminated.

Therefore, the mortar 1 protective layer 3 of the present invention uses LiAlSiO ₄ having a negative thermal expansion coefficient (thermal contraction rate) as a base material component, and a material having a positive thermal expansion coefficient as a filler (thermal expansion coefficient) For example, one or more of MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ , LiAlSi ₂ O ₆ are selected. , By adjusting the thermal expansion coefficient of the protective layer 3 so that the ratio of the thermal expansion coefficient of the protective layer 3 to the thermal expansion coefficient of the main body 2 of the mortar 1 becomes 1: 1-2: 1, The adhesion to the mortar 1 is improved, and it becomes difficult to peel off the mortar 1.

The thermal expansion coefficient of the protective layer 3 of the present invention is calculated as follows: The thermal expansion coefficient of the matrix component is A, the mass% in the protective layer 3 is x%, and the density is ρ _A The filler has a coefficient of thermal expansion B, the percentage by mass in the protective layer 3 is y%, and the density is _{B B.}

  When only one filler is used, the thermal expansion coefficient of the protective layer 3 of the present invention is calculated based on the following formula (1).

  When the filler is two or more (n ≧ 2), the thermal expansion coefficient of the protective layer of the present invention is calculated based on the following equation (2).

Physical properties such as thermal expansion coefficient and density of the material used in the present invention are shown in Table 1.

  The mortar 1 for firing lithium ion battery electrode material of the present invention includes the main body 2 and the protective layer 3, and the main body 2 of the mortar 1 is mainly composed of cordierite, mullite, or a mixture thereof, and The protective layer 3 is applied to the surface of the mortar 1 body 2 in contact with the electrode material. The main body 2 of the mortar 1 can use a commercially available thing, for example, an appropriate amount of binder and water are added to mullite or mullite and cordierite and mixed, the obtained wet powder is added to a mold, and it is press-formed After being dehydrated, it is dehydrated and baked at high temperature.

The mortar 1 for firing lithium ion battery electrode material of the present invention can be produced by the following method, which comprises: (1) firing the main body 2 of the mortar 1 from cordierite, mullite or a mixture thereof And (2) forming the protective layer 3 by applying the surface in contact with the electrode material of the main body 2 of the mortar 1.
The step (1) can be carried out based on various known methods for producing a mortar 1 body 2.
As the step (2), known coating methods known at present can be used, and a matrix component (LiAlSiO ₄ ) and a filler (eg, MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , A coating solution containing at least one selected from MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ and LiAlSi ₂ O ₆ is applied to the inner surface 21 in contact with the electrode material of the mortar 1 main body 2 and dried The coating layer 3 is formed.

  As a coating method, various known methods such as a dip coating method, a spray coating method, and a brush coating method can be used.

  EXAMPLES Hereinafter, examples of the present invention will be described. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

Example 1
Weigh 85 g of LiAlO ₂ (made by Wako Pure Chemical Industries, Ltd.) and 15 g of LiAlSiO ₄ (made by MARUSU GLAZE Co., Ltd.) into a 1 L ceramic pot and add 300 ml of zirconium beads and 300 ml of water. The pot is closed and ground at room temperature for 5 hours at a rotational speed of 100 rpm, and then the zirconium beads are removed, and a suitable amount of water is added to obtain a uniform suspension with a solid content of 30%.

A ceramic test piece (the thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, area 80 cm ² , mullite A protective layer 3 having a thickness of about 100 μm was formed on a mixture of cordierite, dried in an oven at 100 ° C., placed in a calcining furnace, and calcined at 1300 ° C. for 20 hours. After cooling to room temperature, a part of the protective layer 3 was scraped off and subjected to an XRD test. The results are shown in FIG. From FIG. 1, LiAlO ₂ and LiAlSiO ₄ are distributed in the protective layer 3 and there is no significant change in the structure. Further, the adhesion of the protective layer 3 was evaluated by visual inspection based on the following criteria. The results are shown in Table 2.

Adhesion effect of protective layer 3:
Good: Good adhesion, no cracks on the surface of the protective layer 3. Poor: Cracks occurred on the surface of the protective layer 3.

Example 2-5
The conditions shown in Table 2 were performed in the same manner as in Example 1, and the adhesion of the protective layer 3 was evaluated. The results are shown in Table 2.

Comparative Example 1-5
The adhesion of the protective layer 3 was evaluated in the same manner as in Example 1 under the conditions shown in Table 2 and the results are shown in Table 2.

  Furthermore, cobalt oxide (manufactured by Wako Pure Chemical Industries, Ltd.) and lithium carbonate (manufactured by SQM Co., Ltd.), which are raw materials of lithium cobaltate, are mixed, and the ceramic test with the protective layer 3 prepared in Examples 1 to 5 is performed. The piece was placed on the piece and baked at 1030 ° C. for 10 hours to prepare a positive electrode material. Thereafter, the fired lithium cobaltate powder was removed, and the change in the protective layer 3 after firing was observed, and it was confirmed that the ceramic test piece did not significantly change, so that the above-mentioned formed positive electrode material material Was found not to react with the protective layer 3. On the other hand, after firing the ceramic test piece without the protective layer 3 in the same manner, a reddish brown, hard-to-remove adhesion layer is formed on the ceramic test piece, and it is expressed that the above-mentioned positive electrode material has reacted with the ceramic test piece. The

Example 6
Lithium carbonate powder and cobalt oxide powder were mixed at high speed in proportion of Li / Co molar ratio of 1.03. About 5 kg of the obtained mixed powder was placed in a mortar 1 composed of a mixture of mullite and cordierite, and the protective layer 3 shown in Example 1 was applied to the inner surface 21 of the mortar 1. The material is sintered under the following conditions: The temperature is raised to 1030 ° C. over 6 hours, held for 10 hours, and after reaction, cooled to normal temperature for 4 hours. The mortar 1 was taken out, and the lithium cobaltate product was taken out, and the color change and adhesion of the mortar 1 bottom portion 211 were observed. Thereafter, sintering was repeated in the same manner, and changes in the mortar 1 were observed. The results are shown in Table 3 and evaluated as follows.
:: The lithium cobaltate product can be easily taken out and there is no residue on the surface of mortar 1 匣: There is residue on the surface of mortar 1-: Stop using x: Damage to mortar 1 There is

Comparative example 6
An experiment was conducted in the same manner as in Example 6 except that the protective layer 3 as in Example 1 was not provided, and changes in the mortar 1 were observed. The same evaluation as in Example 6 was performed, and the results are shown in Table 3.

  In Comparative Example 6, the solid content remaining on the inner surface bottom of the mortar 1 adheres during the sixth sintering, and a part of the bottom 211 of the inner surface 21 is peeled off. In addition, since a remarkable reddish brown discoloration was observed except that the blue color of cobalt remained, a chemical reaction occurred with the raw material of the reaction and the bottom material of the mortar, so some of the lithium cobaltate was at the bottom of the mortar 211 It is hard to be attached and removed. If it is forcibly removed, a part of the product generated by the reaction of the bottom material of the mortar 1 and lithium mixes with the lithium cobaltate product, and the impurities increase. On the other hand, in Example 6, the lithium cobaltate product is easily removed without noticeable peeling and cracking of the surface of the mortar 1 in addition to the blue cobalt residue even after firing ten times. I was able to From the above results, by using the protective layer 3 of the present invention, the positive electrode material can be effectively inhibited from reacting with the mortar 1 in the process of sintering, and the life can be extended, It has been stated that the goal of reducing the cost of manufacturing positive electrode material can be achieved.

  As described above, in the present embodiment, the entire surface of the inner surface including the bottom portion and the wall surface of the inner surface of the main body 2 is covered, but in the embodiment the bottom portion or the bottom surface and the partial wall surface of the inner surface of the main body are also covered It is within the scope of the present invention.

Reference Signs List 1 bowl 2 main body 21 inner surface 211 bottom portion 212 wall surface 3 protective layer

Claims (7)

Body and
A protective layer covering at least the bottom of the inner surface of the body;
In a firing pot for lithium ion battery electrode material comprising
The above-mentioned protective layer contains LiAlSiO ₄ and one or both of a metal oxide and a metal salt having a positive coefficient of thermal expansion, and a lithium ion battery electrode material firing pot.   The baking pot according to claim 1, wherein the ratio of the thermal expansion coefficient of the protective layer to the thermal expansion coefficient of the mortar body is 1: 1 to 2: 1. The metal oxide and the metal salt are selected from MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , MgSiO ₂ , MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ , LiAlSi ₂ O ₆ or one The mortar for firing lithium ion battery electrode material according to claim 1 or 2, wherein the material is two or more substances.   The said main body is formed by a cordierite, a mullite, or those mixtures, The mortar for lithium ion battery electrode material baking of any one of the Claims 1-3 characterized by the above-mentioned. The protective layer comprises a base component which is LiAlSiO ₄ ,
A protective layer for firing a lithium ion battery electrode material for firing, comprising: a filler having a positive coefficient of thermal expansion, either or both of a metal oxide and a metal salt.   The protective layer for a lithium ion battery electrode material firing mortar according to claim 5, wherein the ratio of the thermal expansion coefficient of the protective layer to the thermal expansion coefficient of the mortar body is 1: 1 to 2: 1. . The filler is selected from one or more of MgO, SnO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , MgAl ₂ O ₄ , LiAlO ₂ , Li ₂ ZrO ₂ , LiAlSi ₂ O ₆ The protective layer of the kiln for lithium ion battery electrode materials baking of Claim 6 or 7 characterized by these.

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