Method for estimating the molar ratio of lithium derived from lithium tungstate, estimation apparatus, and method for manufacturing lithium-ion secondary batteries.

Abstract

This invention provides a method for estimating the amount of coating present on the surface of a positive electrode active material. [Solution] An estimation method comprising: obtaining the lithium content (Li) and the content of metals other than lithium in the positive electrode active material (Me) in the battery, assuming that the lithium content derived from the positive electrode active material is 1 mole, and calculating the ratio of Li to Me; obtaining the amount of Ni and Li mixed in the positive electrode active material and calculating the molar ratio of the mixing amounts; obtaining the lithium carbonate content and calculating the molar ratio of lithium derived from lithium carbonate; obtaining the lithium hydroxide content and calculating the molar ratio of lithium derived from lithium hydroxide; and calculating the molar ratio of lithium derived from lithium tungstate using the following formula (1). [Li / Me]-(1-[Ni mixing])=[Li mixing]+[Li2CO3]+[LiOH]+[Lithium tungstate] Equation (1)

Claims

1. A method for estimating the molar ratio of lithium derived from lithium tungstate, in a lithium-ion secondary battery comprising a positive electrode active material having a lithium tungstate coating layer, where the lithium content derived from the positive electrode active material is set to 1 mole, The lithium content (Li) in the lithium-ion secondary battery and the content of metals other than lithium (Me) in the positive electrode active material are obtained, and the ratio of Li to Me is calculated. Obtain the amount of Ni and Li mixed in the positive electrode active material, and calculate the molar ratio of each mixing amount. The lithium carbonate content in the lithium-ion secondary battery is obtained, and the molar ratio of lithium derived from the lithium carbonate is calculated. The lithium hydroxide content in the lithium-ion secondary battery is obtained, and the molar ratio of lithium derived from the lithium hydroxide is calculated. The molar ratio of lithium derived from the lithium tungstate is calculated using the following formula (1), and the method is as follows: Estimation method. [Li / Me] - (1 - [Ni mixing]) = [Li mixing] + [Li ２ CO ３ ] + [LiOH] + [Lithium tungstate] ... Equation (1) In the above formula (1), [Li / Me] is the ratio of Li to Me, [Ni mixing] is the molar ratio of the Ni mixing amount. [Li mixing] is the molar ratio of the amount of Li mixing. [Li ２ CO ３ ] is the molar ratio of lithium derived from lithium carbonate, [LiOH] is the molar ratio of lithium derived from lithium hydroxide, [Lithium tungstate] is the molar ratio of lithium derived from lithium tungstate.

2. The method further comprises calculating the molar ratio of lithium tungstate from the molar ratio of lithium derived from the lithium tungstate. The estimation method according to claim 1.

3. The lithium tungstate is \(^{7}Li\) ２ WO ４ ·4H ２ O, Li ２ WO ４ , Li ４ WO ５ , Li ６ WO ６ , Li ２ W ４ O １３ , Li ２ W ２ O ７ , Li ６ W ２ O ９ , Li ２ W ２ O ７ , Li ２ W ５ O １６ , Li ９ W １９ O ５５ , Li ３ W １０ O ３０ , Li １８ W ５ O １５ selected from the group consisting of The estimation method according to claim 1 or claim 2.

4. The lithium content (Li) in the lithium-ion secondary battery and the content of metals other than lithium (Me) in the positive electrode active material were obtained by ICP emission spectroscopy. The amounts of Ni and Li mixing in the positive electrode active material were obtained by neutron diffraction. The lithium carbonate content and the lithium hydroxide content are obtained by titration. The estimation method according to claim 1 or claim 2.

5. A device for estimating the molar ratio of lithium derived from lithium tungstate, in a lithium-ion secondary battery comprising a positive electrode active material having a lithium tungstate coating layer, where the lithium content derived from the positive electrode active material is set to 1 mole, A first acquisition unit that acquires the lithium content (Li) and the content of metals other than lithium (Me) in the lithium-ion secondary battery, A first calculation unit that calculates the ratio of Li to Me, A second acquisition unit for acquiring the amount of Ni mixing and Li mixing in the positive electrode active material, A second calculation unit calculates the molar ratio of each mixing amount, A third acquisition unit for acquiring the lithium carbonate content contained in the lithium-ion secondary battery, A third calculation unit for calculating the molar ratio of lithium derived from the lithium carbonate, A fourth acquisition unit for acquiring the lithium hydroxide content contained in the lithium-ion secondary battery, A fourth calculation unit for calculating the molar ratio of lithium derived from the lithium hydroxide, The system includes a fifth calculation unit that calculates the molar ratio of lithium derived from the lithium tungstate using the following formula (1). Estimation device. [Li / Me] - (1 - [Ni mixing]) = [Li mixing] + [Li ２ CO ３ ] + [LiOH] + [Lithium tungstate] ... Equation (1) In the above formula (1), [Li / Me] is the ratio of Li to Me, [Ni mixing] is the molar ratio of the Ni mixing amount. [Li mixing] is the molar ratio of the amount of Li mixing. [Li ２ CO ３ ] is the molar ratio of lithium derived from lithium carbonate, [LiOH] is the molar ratio of lithium derived from lithium hydroxide, [Lithium tungstate] is the molar ratio of lithium derived from lithium tungstate.

6. A method for manufacturing a lithium-ion secondary battery comprising a positive electrode active material having a lithium tungstate coating layer, Obtain the molar ratio of lithium derived from lithium tungstate from the estimation method described in claim 1, To determine whether the molar ratio is equal to or greater than a predetermined specified amount, If the molar ratio is equal to or greater than a predetermined specified amount, the positive electrode mixture, which is a positive electrode active material with an additive added, is coated onto the positive electrode plate. If the molar ratio is less than a predetermined specified amount, the amount of positive electrode mixture, which is made by adding an additive to the positive electrode active material, is increased when coating the positive electrode plate, compared to when the molar ratio is equal to or greater than the predetermined specified amount. Manufacturing method.

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