JP5433276B2 - Method for producing lithium composite compound - Google Patents

Description

  The present invention relates to a method for producing a lithium composite compound used as an electrode material for a non-aqueous electrolyte secondary battery, a lithium composite compound produced by the method, and a non-aqueous electrolyte 2 using the lithium composite compound as an electrode. Next battery.

  Non-aqueous electrolyte secondary batteries are frequently used as power sources for notebook personal computers (notebook PCs) and power tools. FIG. 1 is a perspective view showing an external appearance of a storage element of a non-aqueous electrolyte secondary battery generally called “lithium ion secondary battery”, and FIG. 2 is an aa line arrow in FIG. FIG. As shown in these drawings, the electricity storage element 1 is a “laminate type”, and a positive electrode material 11 capable of reversibly occluding and releasing lithium ions is applied on a sheet-like current collector 12. A sheet-like positive electrode 10 and a sheet-like negative electrode 20 in which a negative electrode material 21 capable of inserting and extracting lithium ions is applied on a sheet-like current collector 22 are also provided. The positive electrode 10 and the negative electrode 20 are disposed to face each other with a separator 50 therebetween, thereby forming one unit of power generation element 60a. And the electrode laminated body 60 is formed by further laminating at least one unit of power generation elements 60a.

  Tabs 40 for inputting / outputting electric power are attached to the individual current collectors (12, 22) of the positive electrode 10 and the negative electrode 20. The tabs 40 are connected by ultrasonic welding or the like in a stacked state between the positive electrodes 10 and the negative electrodes 20. And while accommodating the electrode laminated body 60 in the exterior body 30 which consists of a bag-like laminate film, while deriving the tab 40 to the exterior of the bag of the exterior body 30, the electrolysis which contains lithium salt in the exterior body 30 The storage element 1 of the laminate type non-aqueous electrolyte secondary battery is completed by filling the liquid and sealingly sealing the laminate film.

  There is also a non-aqueous electrolyte secondary battery having a structure in which the one unit of power generation element 60a is wound in a cylindrical or rectangular tube shape and the cylindrical power generation element is inserted into a cylindrical battery can. The present invention is directed to a lithium composite compound used as an electrode material for such non-aqueous electrolyte secondary batteries.

  The sheet-like electrode, which is a main component constituting the storage element of the nonaqueous electrolyte secondary battery, is manufactured by the following procedure, taking the positive electrode as an example. First, a composite compound of a transition metal and lithium (for example, lithium cobaltate or lithium iron phosphate) that becomes a positive electrode active material is powdered, and then the mixture of the powdery active material and a conductive material such as carbon black is mixed. A binder is added and stirred to produce a slurry-like electrode material for a positive electrode. Next, the slurry-like electrode material is applied to a sheet-like current collector such as a metal foil. And after drying the applied electrode material, it rolls and completes a sheet-like electrode.

  Here, in recent years, non-aqueous electrolyte secondary batteries are not limited to the above-mentioned power sources such as notebook PCs, personal computers, and electric tools, but also power sources such as hybrid vehicles (HEV) and electric vehicles (EV), Alternatively, it is also expected as a high-output power source such as a large stationary power source. As a technique for meeting such demands for higher output, the active material for electrodes is made into “nanoparticles” with a particle size of 1 μm or less to increase the total surface area of the active material, and the fine particles A method has been developed in which a conductive material coating layer is formed on the surface of the activated active material to ensure conductivity.

  That is, in this method, a conductive coating layer made of a conductive material such as carbon is formed on the surface of an active material having a primary particle size of about several tens to 100 nm. It is said that the improvement of the resistance and the reduction of the contact resistance between the particles can be achieved, thereby contributing to the high output of the lithium secondary battery.

  However, even when a lithium secondary battery is fabricated using an active material in which the surface of the primary particles is coated with a conductive material such as carbon as an electrode material, a capacity equivalent to the theoretical capacity cannot be obtained. In addition, the charge / discharge cycle characteristics were not satisfactory, and further improvement was desired.

  Therefore, the present inventors conducted various experiments and conducted intensive research and repeated studies. As a result, when the surface of the primary particles was coated with a conductive material such as carbon, the conductivity could be improved as much as possible. In contrast, the conductive material coating layer becomes a barrier that prevents lithium ions from entering and exiting the active material, resulting in higher energy density and higher output of the lithium secondary battery. It came to the knowledge that density improvement and the improvement of a charge / discharge cycle characteristic would be inhibited.

  The present invention was devised based on the above knowledge, and its purpose is to use as an electrode material of a non-aqueous electrolyte secondary battery, and a method for producing a lithium composite compound capable of increasing its output, And a lithium composite compound produced by the production method, and a lithium secondary battery using the lithium compound as an electrode material.

To achieve the above object, the present invention provides a method for producing a lithium composite compound used as an electrode material for a non-aqueous electrolyte secondary battery,
The particle size of the primary particles of the lithium composite compound is at 1μm or less,
Forming a coating layer of a conductive material on the surface of the primary particles;
A step of forming a defect in the coating layer formed on the surface of the primary particles by treating the powder of the primary particles that has undergone the step;
Have
In the forming step of the defect portion, the defect portion is formed by performing a thermal shock treatment on the primary particles of the lithium composite compound on which the conductive material coating layer is formed.
This is a method for producing a lithium composite compound.

  Alternatively, in the step of forming the defect portion, the primary particle of the lithium composite compound on which the conductive material coating layer is formed may be activated to form the defect portion.

  Alternatively, the defect forming step may be configured such that the defect is formed by subjecting primary particles of the lithium composite compound on which the conductive material coating layer is formed to ultrasonic treatment.

  The lithium composite compound preferably has a crystal structure of either an olivine type or a spinel type.

  According to the method for producing a lithium composite compound according to the present invention, the primary particles of the lithium composite compound used as the electrode material of the non-aqueous electrolyte secondary battery are deficient in the coating layer of the conductive material that covers the surface thereof. The part can be formed.

  In the lithium composite compound in which the defect part is formed in the coating layer of the primary particles, when the electrode is brought into contact with the electrolytic solution, the electrolyte solution easily penetrates from the defect part, and the contact between the electrolyte and the active material Improves. Therefore, the diffusion resistance to the active material of lithium ions due to the coating layer of the conductive material is reduced, and when the storage element is configured by using the lithium composite compound as an electrode material, lithium ion diffusion during charge / discharge becomes smooth. As a result, the lithium ion conductivity is improved, and the energy density, cycle characteristics, and output can be increased as much as possible.

It is a see-through | perspective perspective view which shows the electrical storage element structure of the nonaqueous electrolyte secondary battery common to a prior art example and this invention. It is an aa arrow directional cross-sectional view in FIG.

=== Structure of power storage element of non-aqueous electrolyte secondary battery ===
As an example of the present invention, a storage element of a non-aqueous electrolyte secondary battery using a lithium composite compound produced by the method of the present invention as an electrode material is given. As a specific embodiment thereof, for example, the same form as that of the power storage element 1 of the conventional nonaqueous electrolyte secondary battery shown in FIG. 1 can be adopted. However, in this embodiment, the lithium composite compound used for the sheet electrode 10 on the positive electrode side is manufactured by a method different from the conventional method, thereby increasing the output of the storage element 1 of the nonaqueous electrolyte secondary battery. Have achieved. Hereinafter, the specific structure of the electrical storage element 1 of the nonaqueous electrolyte secondary battery in a present Example is demonstrated.

=== About Positive Electrode Active Material ===
In this embodiment, the positive electrode active material is manufactured by a method different from the conventional method. As the positive electrode active material, lithium nickelate (LiNiO ₂ ), lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ) and the like are well known, but at present, they are safer than LiNiO _2. LiCoO ₂ is often employed because it has better capacity characteristics than LiMn ₂ O ₄ .

However, in this example, lithium iron phosphate (LiFePO ₄ ) is used instead of the above-described general positive electrode active material. This LiFePO ₄ does not contain expensive cobalt like LiCoO ₂ , but contains iron that is inexpensive and is expected to be stably supplied. In addition, safety is high. Considering current environmental issues and future depletion of fossil fuels, it is indispensable to stably produce mass storage elements for non-aqueous electrolyte secondary batteries. For this reason, LiFePO ₄ is used as a positive electrode active material. Employment is significant.

While LiFePO ₄ has the advantages described above, it has a drawback that its conductivity is lower than that of other positive electrode active materials. Therefore, the demand for fine particles for LiFePO ₄ is greater than that for other positive electrode active materials. And if the problem regarding microparticulation is solved in this LiFePO ₄ , the solution can be applied to other positive electrode active materials. Also from this point of view, this LiFePO ₄ was selected as the positive electrode active material of the storage element in the non-aqueous electrolyte secondary battery according to the example of the present invention. Here, the present invention is more suitable when applied to a lithium composite compound such as LiFePO ₄ , and particularly to a compound having an olivine type or spinel type crystal structure.

=== Production Method of Positive Electrode Active Material ===
First, prior to manufacturing the sheet-like positive electrode, the positive electrode active material itself is manufactured. In this example, a positive electrode active material was produced by the following process steps A to F.
(A) Iron oxalate dihydrate (FeC ₂ O ₄ .2H ₂ O), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), and lithium carbonate (Li ₂ CO ₃ ) are in a predetermined molar ratio. Mix like so.
(B) The mixture obtained in the above (A) is mixed while pulverizing for 10 hours with a ball mill using 2-propanol as a solvent.
(C) The material pulverized and mixed in (B) above is vacuum dried to remove the solvent and obtain a precursor.
(D) The precursor is placed in an alumina casserole and calcined in an annular firing furnace at 300 ° C. for 5 hours while flowing argon at 0.5 L / min.
(E) The primary precursor of LiFePO ₄ having a particle size of about several tens to 100 nm is calcined at 650 ° C. for 20 hours while circulating argon at 0.5 L / min. A powder (hereinafter, positive electrode active material) in which a conductive carbon coating layer is formed on the surface of the particles is synthesized.
(F) A defective part is formed in the coating layer covering the surface of the primary particles of the LiFePO ₄ powder synthesized in (E). Here, in forming the defect portion, representative examples of the technique include four types of thermal shock treatment, activation treatment, ultrasonic treatment, and mechanical shock treatment. Hereinafter, the coating layer in the surface of the primary particles of the LiFePO ₄ powder shows a specific example of forming the defect by the methods of the four types as the first to fourth embodiments.

<< First Embodiment >>
In the first embodiment, in the step of forming the defect, the primary particle of the lithium composite compound on which the conductive material coating layer is formed is subjected to a thermal shock treatment to form the defect in the coating layer made of the conductive material. To do. That is, the LiFePO ₄ powder synthesized in the above (E) is placed in an inert gas atmosphere of a constant temperature bath at a predetermined temperature and left for a while until the temperature of the LiFePO ₄ powder uniformly rises to the predetermined temperature. Thereafter, the LiFePO ₄ powder taken out from the thermostatic bath is immersed in liquid nitrogen and rapidly cooled.
Then, this rapid cooling causes a rapid temperature difference between the primary particles of LiFePO ₄ and the coating layer on the surface thereof, and cracks are generated in the coating layer of conductive carbon due to the relative volume difference. Defects in the layer will be formed.

Here, in the first embodiment, the predetermined temperature is set to five types of 200 ° C., 400 ° C., 600 ° C., 800 ° C., and 1000 ° C., and thermal shock treatment is individually performed at each set temperature. Thus, five types of samples in which cracks were generated in the coating layer on the primary particle surface of LiFePO ₄ were prepared. That is, Sample 1 quenched from 200 ° C., Sample 2 quenched from 400 ° C., Sample 3 quenched from 600 ° C., Sample 4 quenched from 800 ° C., and Sample 5 quenched from 1000 ° C. 5 types were produced.

<< Second Embodiment >>
In the second embodiment, in the step of forming the defect portion, the primary particles of the lithium composite compound on which the conductive material coating layer is formed are subjected to an activation treatment, and the coating layer made of the conductive material covering the surface is defective. Forming part. That is, potassium hydroxide (KOH) as an activation catalyst is added to the LiFePO ₄ powder synthesized in (E), and forced mixing is performed using alcohol as a solvent. The amount of KOH added is 1 to 2 times the carbon weight of the active material, and an activation treatment is performed at 700 ° C. for 0.5 to 4 hours after a dehydration step at 400 ° C. for 2 hours.
Then, by this activation treatment, the coating layer on the surface of the primary particles in the LiFePO ₄ powder is etched in the activated portion to reduce the thickness of the coating layer, and a recess or a void as a defective portion is formed. Will be.

  Here, in the said 2nd Embodiment, the said activation process time was set to five types, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, and 5 types of samples were produced. That is, the sample 6 subjected to the activation treatment for 0.5 hours, the sample 7 subjected to the activation treatment for 1 hour, the sample 8 subjected to the activation treatment for 2 hours, and the sample 9 subjected to the activation treatment for 3 hours. And the sample 10 which performed the activation process for 4 hours was produced.

<< Third Embodiment >>
In the third embodiment, in the defect forming step, the primary particles of the lithium composite compound on which the conductive material coating layer is formed are subjected to ultrasonic treatment to form the defect in the coating layer made of the conductive material. . That is, the LiFePO ₄ powder synthesized in (E) above is placed in a 2-propanol solvent degassed with argon gas, and subjected to ultrasonic treatment (frequency 100 kHz) for a predetermined time in an argon gas atmosphere.
Then, due to the high-frequency vibration of the ultrasonic wave, a crack or peeling occurs physically in a part of the conductive carbon of the coating layer, and a defect portion is formed in the coating layer. Note that after this ultrasonic treatment, the solvent in the LiFePO ₄ powder is removed by a vacuum dryer.

  Here, in the third embodiment, five types of samples were prepared by setting the ultrasonic treatment time to 6 hours, 12 hours, 24 hours, 36 hours, and 48 hours. That is, the sample 11 subjected to the ultrasonic treatment for 6 hours, the sample 12 subjected to the ultrasonic treatment for 12 hours, the sample 13 subjected to the ultrasonic treatment for 24 hours, and the ultrasonic treatment for 36 hours were applied. Sample 14 and Sample 15 that had been subjected to ultrasonic treatment for 48 hours were prepared.

<< 4th Embodiment >>
In the fourth embodiment, in the step of forming the defect portion, the primary particles of the lithium composite compound on which the conductive material coating layer is formed are subjected to mechanical impact treatment, and the defect portion is formed in the coating layer made of the conductive material. To do. That is, the LiFePO ₄ powder synthesized in (E) is forcibly stirred and mixed for a predetermined time using a dry jet mill in a nitrogen atmosphere.
Then, mechanical impact is applied to the primary particles of the LiFePO ₄ powder to polish the particle surface, and cracks or peeling are physically generated in a part of the conductive carbon coating layer on the surface.

  Here, in the fourth embodiment, five types of samples were prepared by setting the mechanical impact treatment time to 6 hours, 12 hours, 18 hours, 24 hours, and 30 hours. That is, the sample 16 subjected to the mechanical impact treatment for 6 hours, the sample 17 subjected to the mechanical impact treatment for 12 hours, the sample 18 subjected to the mechanical impact treatment for 18 hours, and the mechanical impact for 24 hours. Sample 19 subjected to the treatment and Sample 20 subjected to the mechanical impact treatment for 30 hours were produced.

=== Production Method of Positive Electrode ===
In the sheet-like positive electrode in this example, the positive electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride as a binder (binder) are in a weight ratio of 90: 5: 5. The mixture is adjusted and mixed, and N-methylpyrrolidone is further added to form a positive electrode slurry, which is applied to a sheet-like current collector.
That is, the slurry-like positive electrode material prepared and mixed as described above is applied onto the aluminum foil 12 which is a positive electrode sheet-like current collector and dried. Then, when the coated surface is rolled by a rolling roller and the tab 40 is attached to the current collector 12, the sheet-like positive electrode 10 is completed.

Here, 20 types of LiFePO ₄ powders (positive electrode active materials) of Samples 1 to 20 described above were individually used individually as the sheet-like positive electrode. That is, these sheet-like positive electrodes are the five types of positive electrodes in the first embodiment group using the samples 1 to 5 of the first embodiment in which the defect portion is formed in the coating layer by thermal shock treatment, and the activation treatment. Five types of positive electrodes of the second embodiment group using the samples 6 to 10 of the second embodiment in which the defect portion is formed in the coating layer by the positive electrode active material, and the third embodiment in which the defect portion is formed in the coating layer by ultrasonic treatment Five types of positive electrodes of the third embodiment group using samples 11 to 15 of the form as the positive electrode active material, and samples 16 to 20 of the fourth embodiment in which the defect portion is formed in the coating layer by mechanical impact treatment are used as the positive electrode active material The fourth embodiment group is classified into five types of positive electrodes.

=== Method for Producing Negative Electrode ===
The negative electrode of the nonaqueous electrolyte storage element of this example is manufactured in the same manner as the conventional nonaqueous electrolyte storage element. Specifically, a solvent (N-methylpyrrolidone) was added to a mixture of graphite and a binder (polyvinylidene fluoride) as a negative electrode active material to obtain a slurry-like negative electrode material. The weight ratio of graphite, binder and solvent was 95: 3: 2.
The slurry-like negative electrode material thus prepared is applied onto the copper foil 22 which is a negative electrode sheet-like current collector and dried. Then, when the coated surface is rolled using a rolling roller and the current collecting tab 40 is attached, the sheet-like negative electrode 20 is completed.

=== Assembly ===
Next, the process of assembling the electrical storage element 1 of the nonaqueous electrolyte secondary battery shown in FIGS. 1 and 2 using the sheet-like positive electrode 10 and the sheet-like negative electrode 20 described above will be described.

First, the sheet-like positive electrode 10 and the sheet-like negative electrode 20 are arranged to face each other with the separator 50 interposed therebetween to produce one unit of the laminated body 60a, and the electrode laminated body 60 formed by further laminating a predetermined number of the laminated bodies 60a is vacuumed. It is dried at 105 ° C. for 20 hours.
And after connecting each tab 40 attached to the sheet-like collector (12, 22) with positive electrodes and negative electrodes, the electrode laminated body 60 is made into thickness 0 in the glow box in argon atmosphere. .Into the bag of the outer package 30 made of 11 mm aluminum laminate film. At this time, the tab 40 is led out of the exterior body 30. And after inject | pouring electrolyte solution in the exterior body 30, a laminate film is thermocompression-bonded and sealed, and the electrical storage element 1 of the nonaqueous electrolyte secondary battery shown in FIG. 1 is finally completed. The electrolytic solution was prepared by further adding vinylene carbonate to a solution obtained by dissolving 1 mol / L LiPF6 in a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3: 7.
And the electric storage element 1 of a total of 20 types of non-aqueous-electrolyte secondary batteries is used as mentioned above using the sheet-like positive electrode 10 produced 5 each for each 1st-4th embodiment group mentioned above, respectively. Assembled.

=== Characteristic evaluation ===
The storage elements of the 20 types of non-aqueous electrolyte secondary batteries in the above examples are classified into first to fourth embodiment groups according to the treatment mode of the positive electrode active material, and each of the embodiment groups The capacity characteristics of each power storage element 1 were compared with the capacity characteristics of the power storage elements of a conventional nonaqueous electrolyte secondary battery.
Here, the storage element of each embodiment group and the conventional storage element differ only in the method for manufacturing the positive electrode material, and the other negative electrode manufacturing method and the subsequent assembly procedure are the same. That is, the following conventional products were produced and compared, with different methods for producing the positive electrode material (having no defect forming process step for the coating layer).

<Conventional cathode material>
The positive electrode active material (LiFePO ₄ ), the conductive material (acetylene black), and the binder (polyvinylidene fluoride) were weighed so as to have a predetermined weight ratio, and then the solvent (N methylpyrrolidone) was added to the mixture and stirred. Thus, a positive electrode material of Conventional Product 1 was produced. Here, the coating portion of the conductive carbon coating the surfaces of the primary particles of the positive electrode active material was not treated without performing the defect portion forming treatment for losing it. The weight ratio of the positive electrode active material, the conductive material, and the binder was 90: 5: 5.

<Capacitance characteristics>
In each of the first to fourth embodiment groups, in which the defect forming process of the coating layer is different, each of the six types of non-aqueous electrolytes, that is, a power storage element manufactured using five types of samples and a conventional power storage element The electricity storage device was subjected to constant current charging at a temperature of 25 ° C. at a charging rate of 0.2 C until the voltage reached 4.0 V, and then constant current until the final voltage reached 2.0 V at various discharge rates. Discharge was performed and the discharge capacity of each power storage element was measured.

  The measurement results are shown in Tables 1 to 4 below. Here, the capacity | capacitance of each electrical storage element is shown by the relative value when the theoretical capacity | capacitance calculated | required from the filling amount of the positive electrode active material is set to 100. FIG. The ratio in the table indicates the ratio when the theoretical capacity is 100.

この表１に示した結果から、熱的衝撃処理を施した第１実施形態グループに係る非水電解液二次電池の蓄電素子では、試料１〜３を用いた蓄電素子にあっては、全ての放電レートにおいて、すなわち、小電流で放電しても、大電流で放電しても、ともに従来品の蓄電素子以上の高い容量を得ることができた。特に加熱処理温度を６００℃とした試料３を用いた蓄電素子の容量増大効果が顕著であった。すなわち、高出力化が達成できていることが確認できた。

From the results shown in Table 1, in the storage element of the nonaqueous electrolyte secondary battery according to the first embodiment group subjected to the thermal shock treatment, all the storage elements using Samples 1 to 3 Thus, it was possible to obtain a capacity higher than that of the conventional power storage element, both when discharged at a small current and when discharged at a large current. In particular, the effect of increasing the capacity of the power storage element using Sample 3 with a heat treatment temperature of 600 ° C. was remarkable. That is, it was confirmed that high output was achieved.

  In addition, the storage element using Sample 4 with a heat treatment temperature of 800 ° C. obtained a higher capacity than the conventional storage element at a discharge rate of 0.2 C and 0.5, but 1.0 C, 2 The discharge rates of 0.0 C and 3.0 C were lower than the capacity of the conventional power storage element. That is, from the qualitative viewpoint, the effect of increasing the capacity was more remarkable when the discharge rate was low.

  Here, in the electric storage element using Sample 5 whose heat treatment temperature was 1000 ° C., the capacity was lower than that of the conventional product at all discharge rates. The reason why the capacity is lower than that of the conventional product is that the defective portion is formed too large in the coating layer of the conductive material, and as a result, the conductivity is impaired and the resistance of the electrode is increased. Can be considered.

この表２に示した結果から、賦活処理を施した第２実施形態グループに係る非水電解液二次電池の蓄電素子では、試料６と試料７とを用いた蓄電素子にあっては、全ての放電レートにおいて、すなわち、小電流で放電しても、大電流で放電しても、ともに従来品の蓄電素子以上の高い容量を得ることができた。特に賦活処理の時間を１時間とした試料７を用いた蓄電素子の容量増大効果が顕著であった。すなわち、高エネルギー密度化が達成できていることが確認できた。

From the results shown in Table 2, in the storage element of the nonaqueous electrolyte secondary battery according to the second embodiment group subjected to the activation treatment, all the storage elements using the sample 6 and the sample 7 Thus, it was possible to obtain a capacity higher than that of the conventional power storage element, both when discharged at a small current and when discharged at a large current. In particular, the effect of increasing the capacity of the electricity storage device using Sample 7 in which the activation treatment time was 1 hour was remarkable. That is, it was confirmed that high energy density was achieved.

  In addition, the storage element using Sample 8 with a treatment time of 2 hours had a higher capacity than the conventional storage element at a discharge rate of 0.2 C, but 0.5 C, 1.0 C, 2. The discharge rates of 0 C and 3.0 C were lower than the capacity of the conventional power storage element. That is, from the qualitative viewpoint, the effect of increasing the capacity was more remarkable when the discharge rate was low.

  Here, in the electric storage element using the sample 9 and the sample 10 whose processing times were 3 hours and 4 hours, the capacity was lower than that of the conventional product at all discharge rates. The reason why the capacity becomes lower than that of the conventional product is that, as in the case of the first embodiment group, the defect portion is formed too large in the coating layer of the conductive material, and as a result, the conductivity is impaired. It can be considered that the resistance of the electrode increases.

この表３に示した結果から、超音波処理を施した第３実施形態グループに係る非水電解液二次電池の蓄電素子では、試料１１〜１５を用いたいずれの蓄電素子にあっても、全ての放電レートにおいて、すなわち、小電流で放電しても、大電流で放電しても、ともに従来品の蓄電素子以上の高い容量を得ることができた。特に、処理時間を２４時間とした試料１３、３６時間とした試料１４、並びに４８時間とした試料１５を用いた蓄電素子の容量増大効果が顕著であった。すなわち、高エネルギー密度化が達成できていることが確認できた。また、定性的に見て、放電レートが低い場合の方が容量の増大効果が顕著であった。

From the results shown in Table 3, in the storage element of the nonaqueous electrolyte secondary battery according to the third embodiment group subjected to the ultrasonic treatment, in any storage element using the samples 11 to 15, At all discharge rates, that is, whether discharging with a small current or discharging with a large current, it was possible to obtain a capacity higher than that of a conventional power storage element. In particular, the effect of increasing the capacity of the electricity storage device using Sample 13 with a treatment time of 24 hours, Sample 14 with a treatment time of 36 hours, and Sample 15 with a treatment time of 48 hours was significant. That is, it was confirmed that high energy density was achieved. Further, qualitatively, the capacity increasing effect was more remarkable when the discharge rate was low.

この表４に示した結果から、機械的衝撃処理を施した第４実施形態グループに係る非水電解液二次電池の蓄電素子では、試料１７と試料１８とを用いた蓄電素子にあっては、全ての放電レートにおいて、すなわち、小電流で放電しても、大電流で放電しても、ともに従来品の蓄電素子以上の高い容量を得ることができた。特に処理時間を１８時間とした試料１８を用いた蓄電素子の容量増大効果が顕著であった。すなわち、高エネルギー密度化が達成できていることが確認できた。

From the results shown in Table 4, in the storage element of the nonaqueous electrolyte secondary battery according to the fourth embodiment group subjected to the mechanical shock treatment, the storage element using the sample 17 and the sample 18 At all discharge rates, that is, whether discharging with a small current or discharging with a large current, it was possible to obtain a capacity higher than that of the conventional power storage element. In particular, the effect of increasing the capacity of the electricity storage device using Sample 18 with a treatment time of 18 hours was remarkable. That is, it was confirmed that high energy density was achieved.

  In addition, the storage element using Sample 16 with a treatment time of 6 hours had a higher capacity than the conventional storage element at discharge rates of 0.2C, 0.5C, 1.0C, and 2.0C. However, at the discharge rate of 3.0 C, the capacity of the conventional power storage device was lower. Further, in the electricity storage device using the sample 19 with a treatment time of 24 hours, a higher capacity than that of the conventional electricity storage device was obtained at a discharge rate of 0.2 C. However, 0.5 C, 1.0 C, 2. The discharge rates of 0 C and 3.0 C were lower than the capacity of the conventional power storage element. That is, from the qualitative viewpoint, the effect of increasing the capacity was more remarkable when the discharge rate was low.

  Here, in the electric storage element using the sample 20 whose processing time was 30 hours, the capacity was lower than that of the conventional product at all discharge rates. The reason why the capacity becomes lower than that of the conventional product is that, as in the case of the first and second embodiment groups, the defective portion is formed too large in the coating layer of the conductive material. It can be considered that the resistance of the electrode is increased due to the loss of the properties.

=== Application to negative electrode ===
In the said Example, the manufacturing method of this invention was applied only to the positive electrode. Of course, the present invention extends to a method for producing a negative electrode, and a defect forming process is performed in which a part of a coating layer of a conductive material covering the surface of a primary particle of a nanoparticulated negative electrode active material is lost. The negative electrode material can be applied and applied.

DESCRIPTION OF SYMBOLS 1 Storage element of non-aqueous electrolyte secondary battery 10 Positive electrode 11 Positive electrode material 12 Positive electrode side sheet-like current collector 20 Negative electrode 21 Negative electrode material 22 Negative electrode side sheet-like current collector 30 Exterior body 40 Tab 50 Separator

Claims (4)

A method for producing a lithium composite compound used as an electrode material for a non-aqueous electrolyte secondary battery,
The primary particle size of the lithium composite compound is 1 μm or less,
Forming a coating layer of a conductive material on the surface of the primary particles;
A step of forming a defect in the coating layer formed on the surface of the primary particles by treating the powder of the primary particles that has undergone the step;
Have
In the forming step of the defect portion, the defect portion is formed by performing a thermal shock treatment on the primary particles of the lithium composite compound on which the conductive material coating layer is formed.
A method for producing a lithium composite compound. A method for producing a lithium composite compound used as an electrode material for a non-aqueous electrolyte secondary battery,
The primary particle size of the lithium composite compound is 1 μm or less,
Forming a coating layer of a conductive material on the surface of the primary particles;
A step of forming a defect in the coating layer formed on the surface of the primary particles by treating the powder of the primary particles that has undergone the step;
Have
In the step of forming the said defect, said defect activation treatment is performed on the primary particles of the lithium composite compound coating layer formed of a conductive material is formed,
A method for producing a lithium composite compound. A method for producing a lithium composite compound used as an electrode material for a non-aqueous electrolyte secondary battery,
The primary particle size of the lithium composite compound is 1 μm or less,
Forming a coating layer of a conductive material on the surface of the primary particles;
A step of forming a defect in the coating layer formed on the surface of the primary particles by treating the powder of the primary particles that has undergone the step;
Have
In the step of forming the said defect, the defect in the primary particles sonication is performed of a lithium composite compound coating layer of conductive material is formed is formed,
A method for producing a lithium composite compound. In any one of claims 1 to 3, wherein the lithium composite compound, method for producing a lithium composite compound, wherein the crystal structure is either olivine or spinel.

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