KR100784588B1 - Method for producing positive electrode material for lithium-ion secondary battery - Google Patents

Abstract

Lithium ion secondary battery positive electrode material manufacturing method according to the invention, by mixing and heat treatment of Li and Co source LiCoO ₂ A first step of synthesizing an active material; A second step of adding Ni, Mn and Li sources to the structurally stabilized LiCoO ₂ at a predetermined molar ratio to mix them; And again heating the mixture a third step for synthesizing the electrode active material O ₂ Li (Ni Co _{⅓ ⅓} Mn _⅓); and a.

Cathode, Zirconia Ball, Tap Density, Layered Structure

Description

Manufacturing method of positive electrode material for lithium ion secondary battery {METHOD FOR PRODUCING POSITIVE ELECTRODE MATERIAL FOR LITHIUM-ION SECONDARY BATTERY}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a flow chart illustrating a process performed a method of manufacturing a cathode material for a lithium ion secondary battery according to the present invention.

Figure 2 is a table comparing the characteristics of the cathode material for a lithium ion secondary battery prepared according to the present invention and the prior art.

The present invention relates to a method for manufacturing a cathode material for a lithium ion secondary battery, and in particular, to prepare a cathode active material by synthesizing a lithium (Li) -nickel (Ni) -cobalt (Co) -manganese (Mn) -based oxide, the tab of the active material The present invention relates to a method for manufacturing a cathode material for a lithium ion secondary battery, in which a process is improved to improve a tap density and charge / discharge characteristics.

Lithium-ion secondary batteries have many advantages over other secondary batteries such as relatively high energy density, high operating voltage and excellent retention and lifespan characteristics, such as personal computers, camcorders, portable phones, portable CD players, PDAs, etc. Widely used in various portable electronic devices.

The lithium ion secondary battery has a predetermined battery case, a positive electrode and a negative electrode having an active material, a positive electrode current collector and a negative electrode current collector to perform a current collecting function, and prevents contact between the positive electrode and the negative electrode and selectively passes lithium ions. It includes a separator, and performs the charge / discharge operation by reversibly transferring lithium ions between the positive electrode and the negative electrode.

LiCoO ₂ as a cathode material of a lithium ion secondary battery Active materials are commercialized, and recently LiCoO ₂ Equal or glass surface in the capacity compared to the active material, and there is used a technique of using cheap price Li (Ni Co _{⅓ ⅓ ⅓} Mn) O ₂ as the positive electrode active material. A related technique of the Republic of Korea Patent Application which discloses a method of synthesis as the Republic of Korea Patent Application No. 2003-16798 and No. that the Li (Ni Co _{⅓ ⅓ ⅓} Mn) O ₂ active material is disclosed a method of synthesizing a conventional method, liquid phase method No. 2005-44771.

However, the Li (Ni Co _{⅓ ⅓} Mn _⅓) prepared according to the prior art O ₂ active material is LiCoO _2, which is already commercially available There is a disadvantage that the bulk density is significantly lower than that of the active material, which makes it difficult to be commercialized. In particular, in the case of the liquid phase method, the yield is very low, which is unsuitable for mass production.

The present invention was devised in consideration of the above-mentioned points, and by adding an additive in a state where LiCoO ₂ was structurally stabilized in advance, a Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material was synthesized to _improve tap density and charge / discharge characteristics. An object of the present invention is to provide a method for manufacturing a cathode material for a lithium ion secondary battery, which is to be further improved.

In order to achieve the above object, a method of manufacturing a cathode material for a lithium ion secondary battery according to the present invention is a LiCoO ₂ by mixing and heat-treating a Li and Co source. A first step of synthesizing an active material; A second step of adding Ni, Mn and Li sources to the structurally stabilized LiCoO ₂ at a predetermined molar ratio to mix them; And again heating the mixture a third step for synthesizing the electrode active material O ₂ Li (Ni Co _{⅓ ⅓} Mn _⅓); and a.

Preferably, in the first step using a ball mill so that the molar ratio of Li and Co is 1.025: 1 Li ₂ CO ₃ , Co ₃ O ₄ And a process of mixing the zirconia balls.

In the first step 2 Co: Ni: Mn = 1 : 1: 1 such that the molar ratio of Ni (OH) _2, and the addition of MnO ₂ and, Li: the molar ratio of _{1: (Ni ⅓ Co ⅓ Mn} ⅓) = 1.025 After adding LiOH.H ₂ O, the process of mixing with zirconia balls using a ball mill is performed.

In accordance with another embodiment of the invention, in the second step 2 Co: Ni: Mn = 1 : 1: 1 such that the molar ratio of the addition of Ni (OH) _2, and MnO _2, and Li: (Ni _⅓ Co _⅓ Mn _⅓) = 1: the step of mixing together with zirconia balls is done after the first addition of LiOH.H ₂ O so as to have a molar ratio of, using a ball mill.

According to a further embodiment of the present invention, wherein in step 2 Co: Ni: Mn = 1 : 1: 1 was added to Ni (OH) _2, and MnO ₂ such that the molar ratio of to, Li: (Ni _⅓ Co _⅓ LiOH.H ₂ O is added to have a molar ratio of Mn _⅓ ) = 1.05: 1, followed by mixing with zirconia balls using a ball mill.

In the heat treatment, the first heat treatment is performed at 450 ° C. for 1 hour, and then the second heat treatment is performed at 950 ° C. for 4 hours.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 schematically shows a process in which a method of manufacturing a cathode material for a lithium ion secondary battery according to the present invention is performed.

As shown in Figure 1, the cathode material manufacturing method according to the present invention is previously LiCoO ₂ Synthesizing Active Material and Structurally Stabilized LiCoO ₂ Adding additives to the active material includes a dual synthetic process for synthesizing the electrode active material O ₂ Li (Ni Co _{⅓ ⅓} Mn _⅓).

First, LiCoO ₂ is mixed and heat treated with Li source and Co source. A process of synthesizing the active material is performed (step S100).

As the Li source and Co source, Li ₂ CO ₃ and Co ₃ O ₄ Is preferably adopted, and the mixing treatment is preferably performed using a ball mill in a state in which zirconia balls are added. Herein, the amount of Li and Co is preferably selected to be Li: Co = 1: 1, Li: Co = 1.025: 1, Li: Co = 1.05: 1, etc. in molar ratio in consideration of the volatilization of lithium during the mixing process. Do. In addition, the mixing treatment using a ball mill is preferably performed for 1 to 4 hours at a rate of 100 RPM.

After the mixing treatment is completed, the first heat treatment is performed at 450 ° C. for 1 hour, and then the second heat treatment is performed at 950 ° C. for 4 hours to form LiCoO _2. The active material is synthesized. At this time, the temperature increase rate is preferably set to 7 ℃ / min to prevent structural instability due to rapid temperature changes.

Thereafter, LiCoO ₂ stabilized with a layered structure The process of adding and mixing Ni, Mn and Li sources to the active material is performed (step S110).

Ni (OH) ₂ and MnO ₂ are preferably used as the Ni source and Mn source, respectively, and LiOH.H ₂ O, which is a hydrate structure, is adopted as the Li source. Moreover, it is preferable to perform the mixing process using a ball mill in the state which injected the zirconia ball. Here, the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) is Li: (Ni _⅓ Co _⅓ Mn _⅓ ) = 1: 1, Li: (Ni _⅓ Co _⅓ Mn _{⅓) = 1.025: 1, Li} : is preferably selected as one such _{as: (Ni ⅓ Co ⅓ Mn ⅓} ) = 1.05. In addition, the mixing process using a ball mill may be performed for 1 to 4 hours at a rate of 100 RPM.

Ni, Mn, and Li sources are the LiCoO ₂ After addition to the active material described above LiCoO ₂ And performing a heat treatment of two times the synthesis process, to complete the synthesis Li (Ni Co _{⅓ ⅓ ⅓} Mn) O ₂ active material (step S120).

Or less, and are compared to a particular embodiment and the conventional Li (Ni Co _{⅓ ⅓ ⅓} Mn) O ₂ active material production process (Comparative Example) of the present invention to aid in the understanding of the present invention will be described.

Example  One

Li ₂ CO ₃ and Co ₃ O ₄ are mixed in a ball mill with zirconia balls so that the molar ratio of Li and Co is 1.025: 1, and LiCoO _{2 is} subjected to the first and second heat treatment under the above-described heat treatment conditions. An active material was synthesized.

Then, LiCoO ₂ stabilized in a layered structure The active material is Co: Ni: Mn = 1: 1: 1 was added to the lock Ni (OH) ₂ and MnO ₂ doedo the molar ratio of the _{Li: (Ni ⅓ Co ⅓ Mn} ⅓) = 1.025: LiOH such that the molar ratio of 1. by the addition of H ₂ O were mixed using a ball mill with zirconia balls, and again 1, performing a second heat treatment by combining the active O ₂ Li (Ni Co _{⅓ ⅓} Mn _⅓).

After synthesizing a Li (Ni _⅓ Co _⅓ Mn _⅓) O ₂ active material for the measurement of the density characteristic, and then the synthesized Li (Ni _⅓ Co _⅓ Mn _⅓) O ₂ active material was pulverized, classified to dry tap density (Tap density), ie, the density of the compacted state under constant conditions was measured.

In order to measure the charge and discharge characteristics, 100 g of Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material was placed in a 500 ml reactor, and a small amount of N-methyl pitolidon (NMP) and a binder (PVDF) were added to the mixer (Mixer). ) Was kneaded, pressed and dried on aluminum foil to prepare electrodes, and the charging and discharging efficiency of any coin cell was calculated.

Example  2

Ni (OH) ₂ and MnO ₂ were added so that the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) was 1: 1, and the remaining conditions were the same as in Example 1.

Example  3

Ni (OH) ₂ and MnO ₂ were added so that the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) was 1.05: 1, and the remaining conditions were the same as in Example 1.

Comparative example  One

LiOH.H ₂ O, Co ₃ O ₄ , Ni (OH) ₂ and MnO ₂ are mixed with a zirconia ball in a ball mill so that the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) is 1: 1, as described above. Due to such heat treatment conditions, proceed with the first and second heat-treating the active material was synthesized in the O ₂ Li (Ni Co _{⅓ ⅓} Mn _⅓).

Next, in order to measure the density characteristics, the synthesized Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material was pulverized, classified and dried, and then the tap density, that is, the density of the compacted state under a constant condition was measured.

In order to measure the charge and discharge characteristics, 100 g of Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material was placed in a 500 ml reactor, and a small amount of N-methyl pitolidon (NMP) and a binder (PVDF) were added to the mixer (Mixer). ) Was kneaded, pressed and dried on aluminum foil to fabricate an electrode to calculate charge and discharge efficiency for the coin cell.

Comparative example  2

LiOH.H ₂ O, Co ₃ O ₄ , Ni (OH) ₂ and MnO ₂ were added so that the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) was 1.025: 1, and the remaining conditions were the same as in Comparative Example 1 It was.

Comparative example  3

LiOH.H ₂ O, Co ₃ O ₄ , Ni (OH) ₂ and MnO ₂ were added so that the molar ratio of Li and (Ni _⅓ Co _⅓ Mn _⅓ ) was 1.05: 1, and the remaining conditions were the same as in Comparative Example 1 It was.

Comparative example  4

Li ₂ CO ₃ and Co ₃ O ₄ are ball-mixed together with zirconia balls so that the molar ratio of Li and Co is 1.025: 1, and the LiCoO ₂ active material is synthesized by performing the first and second heat treatment under the heat treatment conditions as described above. It was.

LiCoO ₂ After synthesizing the active material, the synthesized LiCoO ₂ for the measurement of density characteristics After pulverizing, classifying and drying the active material, the tap density, that is, the density of the compacted state under a predetermined condition was measured.

In addition, in order to measure the charge and discharge characteristics, LiCoO ₂ 100 g of the active material was placed in a 500 ml reactor, a small amount of N-methyl pitolidon (NMP) and a binder (PVDF) were added, kneaded using a mixer, and pressed and dried on an aluminum foil to prepare an electrode. Charge and discharge efficiency for the cell (Coin cell) was calculated.

Test results of the density and charge and discharge characteristics of the cathode materials prepared according to Examples 1 to 3 and Comparative Examples 1 to 4 as described above are shown in FIG. 2. Here, the density characteristics were tested by a method of measuring the density after putting about 15 g of the dried active material into a 15 ml measuring cylinder and tapping 3,000 times using HT2 of QUANTACHROME of the United States. In the case of the charging characteristic test, the charging current is charged at a charge current of 0.5 mA / cm 2 until it becomes 0.01 V while the potential is regulated in the range of 0 to 1.5 V, and the charging current is 0.02 mA / while maintaining the voltage of 0.01 V. Charging was continued until it became 2 cm <2>. In addition, in the discharge characteristic test, discharge was performed until it became 1.5V with a discharge current of 0.5 mA / cm <2>. In FIG. 2, the charging and discharging efficiency during an initial cycle (1 ^st cycle) during which charging and discharging is performed represents the ratio of the discharge capacitance to the charging capacitance.

Referring to FIG. 2, it can be seen that Examples 1 to 3 have a higher tap density and a higher charge / discharge efficiency than Comparative Examples 1 to 3. In particular, in the case of tap density characteristics, Comparative Example 4, that is, LiCoO ₂ It can be seen that the tap density characteristics of the active material are approached.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, it is possible to improve the tap density and the charge / discharge efficiency compared to the method of adding all the sources in the synthesis of the Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material, and commercialized LiCoO ₂ Compared with the active material, there is an advantage in that it is possible to provide a cathode material for a lithium ion secondary battery having a relatively low price while having an equivalent or superior tap density and charge / discharge efficiency.

Claims (6)

A first step of synthesizing a LiCoO ₂ active material by mixing and heat treating a Li and Co source; A second step of adding Ni, Mn, and Li sources in a predetermined molar ratio to the LiCoO ₂ active material stabilized in a layered structure and mixing the mixture; And A third step of synthesizing the Li (Ni _⅓ Co _⅓ Mn _⅓ ) O ₂ active material by heat-treating the mixture; Method of manufacturing a cathode material for a lithium ion secondary battery comprising a. The method of claim 1, wherein in the first step, Li ₂ CO ₃ , Co ₃ O ₄ using a ball mill so that the molar ratio of Li and Co is 1.025: 1 And a zirconia ball, wherein the cathode material for a lithium ion secondary battery is mixed. The method of claim 2, wherein in the second step, Ni (OH) ₂ and MnO ₂ were added so that a molar ratio of Co: Ni: Mn = 1: 1: 1, _{Li: (Ni ⅓ Co ⅓ Mn} ⅓) = 1.025: 1 after the addition of LiOH.H ₂ O so as to have a molar ratio of, A method for producing a cathode material for a lithium ion secondary battery, characterized in that it is mixed with a zirconia ball using a ball mill. The method of claim 2, wherein in the second step, Ni (OH) ₂ and MnO ₂ were added so that a molar ratio of Co: Ni: Mn = 1: 1: 1, _{Li: (Ni ⅓ Co ⅓ Mn} ⅓) = 1: 1 and then to have a molar ratio of the addition of LiOH.H ₂ O, A method for producing a cathode material for a lithium ion secondary battery, characterized in that it is mixed with a zirconia ball using a ball mill. The method of claim 2, wherein in the second step, Ni (OH) ₂ and MnO ₂ were added so that a molar ratio of Co: Ni: Mn = 1: 1: 1, _{Li: (Ni ⅓ Co ⅓ Mn} ⅓) = 1.05: After the addition of LiOH.H ₂ O so as to have a molar ratio of 1, A method for producing a cathode material for a lithium ion secondary battery, characterized in that it is mixed with a zirconia ball using a ball mill. The method of claim 1, As the heat treatment, the primary heat treatment for 1 hour at 450 ℃, and then the secondary heat treatment for 4 hours at 950 ℃ characterized in that the manufacturing method of the positive electrode material for a lithium ion secondary battery.

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