Lithium-ion battery lithium supplement containing lithium oxide and preparation method thereof

Abstract

The present invention discloses a lithium supplement for lithium-ion batteries containing lithium oxide and a preparation method thereof. The lithium supplement for lithium-ion batteries containing lithium oxide and a preparation method thereof proposed by the present invention include the following steps: placing a lithium hydroxide raw material in a reaction furnace for primary dehydration, wherein the primary dehydration temperature ranges from 150°C to 200°C; performing a secondary dehydration after a first preset time of the primary dehydration, wherein the secondary dehydration temperature ranges from 600°C to 700°C, to obtain a lithium oxide raw material; wherein, during the secondary dehydration process, monitoring the gas pressure in the reaction furnace, when the gas pressure is greater than the first preset gas pressure, lowering the secondary dehydration temperature, and when the gas pressure is less than the second preset gas pressure, raising the secondary dehydration temperature. The present application proposes a lithium supplement for lithium-ion batteries containing lithium oxide and a preparation method thereof, which is intended to improve the purification rate of lithium oxide while ensuring the purity of lithium oxide, and to control the lithium supplementation rate when lithium oxide is used as a raw material for the lithium supplement.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a lithium supplement for lithium ion batteries containing lithium oxide and a preparation method thereof. Background Art

[0002] With the rapid development of society, more and more electronic products are powered by lithium-ion batteries, such as mobile phones, tablets, laptops, etc. that are commonly used in life. In large industrial projects such as drones and electric vehicles, the popularity of lithium-ion batteries is also increasing. At the same time, the performance requirements for lithium-ion batteries are also getting higher and higher.

[0003] The energy density of lithium-ion batteries has a huge impact on the performance of lithium-ion batteries. Among the commonly used negative electrode active materials of lithium-ion batteries, the first efficiency of graphite materials is low, which can only reach 90%, and the theoretical gram capacity is only 372mAh / g; although the theoretical gram capacity of silicon-based materials reaches 4200mAh / g, the first efficiency is only 50-60%. In addition, the consumption and repair of the SEI film and the increase of dead lithium inside the positive and negative electrodes during the cycle of lithium-ion batteries cause the capacity of the battery to continue to decline, resulting in a decrease in the cycle life of the battery. In order to reduce the reduction in battery capacity caused by the irreversible capacity of the battery during the first charge and discharge and cycle, it is usually adopted to supplement part of the active lithium inside the lithium-ion battery to fully improve the above problems. The current lithium replenishment schemes mainly include negative electrode lithium replenishment, positive electrode lithium replenishment, diaphragm lithium replenishment and electrolyte lithium replenishment. In the positive electrode lithium replenishment scheme, a positive electrode lithium replenishment additive is used to make it release lithium ions during the charging process to replenish the irreversible capacity loss of the first charge and discharge. Positive electrode lithium replenishment uses lithium-ion-rich compounds combined with catalysts to enter the electrolyte. Active substances are added to the electrolyte. Under the joint action of active substances and catalysts, these lithium-ion-rich compounds release lithium ions to achieve the lithium replenishment effect. Among them, lithium oxide, as the most common lithium-ion-rich compound, participates in the positive electrode lithium replenishment process.

[0004] The purity of lithium oxide directly affects the lithium supplement effect of the lithium supplement agent. The raw material for preparing lithium oxide is often lithium hydroxide, and the common forms of lithium hydroxide are lithium hydroxide monohydrate and anhydrous lithium hydroxide. Lithium hydroxide is converted into lithium oxide and water after high-temperature heating in a reactor, and the conversion rate increases with increasing temperature. Therefore, in order to speed up the reaction rate, the reaction temperature can be increased. However, in the prior art, within the expected reaction time, the purity of lithium oxide in the product obtained by high-temperature reaction cannot meet expectations. In order to obtain the same purity, sometimes the reaction time at a high reaction temperature is longer than the reaction time at a low reaction temperature. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a lithium-ion battery lithium supplement containing lithium oxide and a preparation method thereof, which aims to improve the purification rate of lithium oxide while ensuring the purity of lithium oxide, and can control the lithium supplement rate when lithium oxide is used as a raw material of the lithium supplement.

[0006] To achieve the above object, the lithium-ion battery lithium supplement containing lithium oxide and the preparation method thereof provided by the present invention include the following steps:

[0007] The lithium hydroxide raw material is placed in a reaction furnace for primary dehydration, and the primary dehydration temperature ranges from 150° C. to 200° C.;

[0008] After a first preset time of the first dehydration, a secondary dehydration is performed, and the secondary dehydration temperature ranges from 600°C to 700°C to obtain a lithium oxide raw material; wherein, during the secondary dehydration process, the gas pressure in the reaction furnace is monitored, and when the gas pressure is greater than the first preset pressure, the secondary dehydration temperature is lowered, and when the gas pressure is less than the second preset pressure, the secondary dehydration temperature is increased.

[0009] According to some embodiments of the present application, the first preset air pressure is 900Pa-1100Pa, and the second preset air pressure is 500Pa-700Pa.

[0010] According to some embodiments of the present application, the method for preparing the lithium supplement for lithium ion batteries further comprises the following steps:

[0011] grinding the lithium oxide raw material to form lithium oxide powder;

[0012] The lithium oxide powder is spread on a conveyor belt and conveyed along a first direction, an electrostatic film is arranged above the conveying path of the lithium oxide powder, static electricity is introduced to the electrostatic film to adsorb the lithium oxide powder on the conveyor belt, and the electrostatic film is conveyed toward the first direction;

[0013] A spraying mechanism is arranged in the transmission path of the electrostatic film, and is arranged downstream of the conveyor belt. The spraying mechanism sprays catalyst onto the lithium oxide powder on the electrostatic film so that the catalyst covers the wall of the lithium oxide powder away from the electrostatic film.

[0014] According to some embodiments of the present application, before the step of spraying the catalyst onto the lithium oxide powder on the electrostatic film, the following steps are also included:

[0015] A vibration device is arranged on the transmission path of the electrostatic film. The vibration device is arranged on the side of the electrostatic film away from the lithium oxide powder. Along the first direction, the vibration device is arranged downstream of the conveyor belt and upstream of the spraying mechanism. The vibration device drives the electrostatic film to vibrate.

[0016] According to some embodiments of the present application, after the step of driving the electrostatic film to vibrate by the vibration device and before the step of spraying the catalyst onto the lithium oxide powder on the electrostatic film, the following steps are also included:

[0017] The portion of the electrostatic film located downstream of the vibration device is turned over so that the lithium oxide powder is placed on top of the electrostatic film.

[0018] According to some embodiments of the present application, after the step of spraying a catalyst onto the lithium oxide powder on the electrostatic film, the lithium oxide powder mixture after the catalyst is sprayed is sintered under an inert gas and then ball-milled at a low speed to obtain a lithium supplement.

[0019] According to some embodiments of the present application, the vibration device is capable of generating sound waves, and the sound waves drive the electrostatic membrane to vibrate.

[0020] According to some embodiments of the present application, a lithium-ion battery lithium supplement includes lithium supplement particles, the lithium supplement particles include a catalyst and lithium oxide, and the catalyst is half-encapsulated in the lithium oxide.

[0021] According to some embodiments of the present application, the particle size of the lithium-supplementing particles ranges from 80 nanometers to 20,000 nanometers.

[0022] According to some embodiments of the present application, the mass of lithium oxide in the lithium-supplementing particles is between 1 and 10 times the mass of the catalyst.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The applicant has found that when a higher temperature is provided for the reaction of lithium hydroxide raw material becoming lithium oxide in the reactor, the dehydration speed of lithium hydroxide in the reactor is accelerated, and the rate of generating water vapor is accelerated. However, according to the original vacuum pump capacity, the water vapor in the reactor cannot be discharged in time. The increased water vapor cannot be discharged in time, resulting in an increase in the air pressure in the reactor. It has been verified that if the air pressure in the reactor is greater than a certain value, the steam in the reactor is saturated, and the reaction in the reactor will stop. This scheme sets a detection device to monitor the air pressure in the above-mentioned reactor. When the reactor is at a certain temperature, after the air pressure in the reactor reaches a certain value, if the air pressure continues to rise, the reaction has a tendency to stop, and this air pressure is recorded as the first preset air pressure. When the detection device detects that the air pressure in the furnace is greater than the first preset air pressure, the temperature in the reactor is reduced, so that the rate of lithium hydroxide in the reactor becoming lithium oxide is reduced, so that the water vapor generated by the reaction per unit time is reduced. At this time, according to the capacity of the vacuum pump of the reactor, the amount of water vapor discharged by the vacuum pump per unit time in the reactor is greater than the amount of water vapor generated in the reactor per unit time, so the pressure in the reactor will be reduced, so that the reaction continues. When the pressure in the reactor is reduced to the pressure before the temperature is raised, if the reactor is kept at a lower temperature, the reaction rate will be reduced. The pressure in the reactor before the temperature is raised is recorded as the second preset pressure. When it is detected that the pressure in the reactor is reduced from a value close to the first pressure to a value close to the second pressure or the pressure in the reactor is less than the second preset pressure, the temperature provided to the reactor is increased to allow the reaction in the reactor to proceed at a high speed. By such an adjustment method, it is ensured that the reaction of lithium hydroxide to lithium oxide in the reactor continues, and the reaction is always carried out at a high speed at a relatively high temperature (and at this temperature, the pressure in the reactor will not increase and the reaction will not stop). Therefore, the lithium oxide obtained according to the expected time has an ideal purity. While increasing the production rate of lithium oxide, the purity of the obtained lithium oxide is guaranteed, making the production efficiency of lithium oxide higher. In the prior art, when the temperature is too high, since the saturated vapor pressure factor is not taken into account, if the reaction is terminated according to the expected time, the purity of the obtained lithium oxide is not enough.

[0025] Furthermore, the applicant discovered that in the prior art, lithium oxide is combined with a catalyst to enter the electrolyte to promote the release of lithium ions. Due to the fully enclosed structure of lithium oxide and the catalyst, that is, lithium oxide completely encapsulates the catalyst, this structure causes lithium oxide to release lithium ions too violently during the first charge and discharge and cycle of the battery. In order to control the time for lithium oxide to release active lithium ions, so that lithium oxide continues to release lithium ions during the first charge and discharge and cycle of the battery, and achieve the purpose of making the lithium replenishment process smooth and smooth, the present application is designed to make the prepared lithium oxide and catalyst form a half-enclosed structure, that is, part of the surface of lithium oxide and the catalyst are attached. The method for preparing a lithium-ion battery lithium replenisher provided by this scheme, through the cooperation of a conveyor belt, an electrostatic film, a vibration module and a spraying mechanism, coordinates to distinguish the weight of lithium oxide particles, controls the contact area between the catalyst and lithium oxide, and forms a half-enclosed structure between the catalyst and lithium oxide.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 The present invention is a flow chart of a method for preparing a lithium supplement for lithium ion batteries according to an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A schematic diagram of the structure of the reactor mentioned in the method;

[0030] Figure 3 This is a schematic diagram of lithium oxide powder processing in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the simultaneous processing of the first batch of ground lithium oxide powder and the second batch of ground lithium oxide powder in an embodiment of the present invention;

[0032] Figure 5 This is a cross-sectional view of the lithium supplement particles prepared in an embodiment of the present invention.

[0033] Description of Figure Numbers:

[0034] Reaction furnace 100; vacuum exhaust pipe 110; crucible vacuum detection sensor 120; lithium hydroxide dehydration furnace 130; vacuum pump 140;

[0035] Conveyor belt 210; electrostatic film 220; adsorption surface 221; vibration device 230; material collection device 240; material spraying mechanism 250;

[0036] Lithium hydroxide powder 310 ; a first batch of lithium oxide powder 320 ; a second batch of lithium oxide powder 330 ; a catalyst 340 .

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or", "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] In the related art, the purity of lithium oxide directly affects the lithium supplement effect of the lithium supplement agent. The raw material for preparing lithium oxide is often lithium hydroxide. In order to increase the rate of preparing lithium hydroxide, a higher temperature is provided to the reactor for the lithium hydroxide reaction. It is expected that the higher the temperature, the shorter the reaction time, so generally when the reaction temperature is increased, the reaction will be terminated in advance. However, in the prior art, when the temperature is too high, since the saturated vapor pressure factor is not taken into account, if the reaction is terminated according to the expected time, the purity of the obtained lithium oxide is not enough. However, the applicant did not initially find that the purity was insufficient due to the saturated vapor pressure, but misplaced the belief that it was caused by the presence of impurities in the raw material itself.

[0042] Based on this, the present scheme sets a detection device to monitor the gas pressure in the above-mentioned reactor. When the reactor is at a certain temperature, after the gas pressure in the reactor reaches a certain value, if the gas pressure continues to rise, the reaction tends to stop, and this gas pressure is recorded as the first preset gas pressure. When the detection device detects that the gas pressure in the furnace is greater than the first preset gas pressure, the temperature in the reactor is lowered to reduce the rate at which lithium hydroxide in the reactor is converted into lithium oxide, so that the water vapor generated by the reaction per unit time is reduced. At this time, according to the capacity of the reactor vacuum pump, the amount of water vapor discharged from the reactor by the vacuum pump per unit time is greater than the amount of water vapor generated in the reactor per unit time, so the pressure in the reactor will be reduced, allowing the reaction to continue. When the gas pressure in the reactor is reduced to the gas pressure before the temperature is raised, if the reactor is kept at a lower temperature, the reaction rate will be reduced. The air pressure in the reactor before the temperature is raised is recorded as the second preset air pressure. When it is detected that the air pressure in the reactor decreases from a value close to the first air pressure to a value close to the second air pressure or when the air pressure in the reactor is less than the second preset air pressure, the temperature provided to the reactor is increased to allow the reaction in the reactor to proceed at a high speed. By such an adjustment method, it is ensured that the reaction of lithium hydroxide to lithium oxide in the reactor continues, and the reaction is always carried out at a high speed at a relatively high temperature (and at this temperature, the air pressure in the reactor will not increase and the reaction will not stop). Therefore, the lithium oxide obtained according to the expected time has an ideal purity. While increasing the production rate of lithium oxide, the purity of the obtained lithium oxide is guaranteed, making the production efficiency of lithium oxide higher. The following is a further elaboration of the embodiments of the present application in conjunction with the accompanying drawings.

[0043] The lithium hydroxide raw material may exist in the form of lithium hydroxide monohydrate, anhydrous lithium hydroxide, or a mixture of lithium hydroxide monohydrate and anhydrous lithium hydroxide. Figure 1 , Figure 1This is a flow chart of a method for preparing a lithium supplement for lithium-ion batteries in one embodiment of the present invention. When the lithium hydroxide raw material used is lithium hydroxide monohydrate or a mixture of lithium hydroxide monohydrate and anhydrous lithium hydroxide, it is necessary to perform a primary dehydration and a secondary dehydration in sequence to convert the lithium hydroxide monohydrate into anhydrous lithium hydroxide and then into lithium oxide; when the lithium hydroxide raw material is anhydrous lithium hydroxide, only a secondary dehydration is required to obtain lithium oxide. The present application provides a method for preparing a lithium supplement for lithium electrons, the method for preparing the lithium supplement includes a method for preparing a lithium supplement raw material (lithium oxide), and the specific preparation method includes the following steps:

[0044] S101: Place the lithium hydroxide raw material in the reactor 100 for the first dehydration, and the temperature range of the first dehydration is 150°C to 200°C. The lithium hydroxide raw material of the present application exists in the form of lithium oxide monohydrate and anhydrous lithium oxide. The first dehydration of the lithium hydroxide raw material in the reactor 100 is the process of reacting the lithium oxide monohydrate of the lithium hydroxide raw material into anhydrous lithium oxide. S101 is carried out under the condition of 150°C to 200°C. For example, S101 can be carried out under the conditions of 150°C, 170°C, 190°C and 200°C. This process will generate water vapor, and a vacuum pump is provided to remove the water vapor generated by the reaction.

[0045] S103: After the first dehydration for a first preset time, a second dehydration is performed, and the temperature range of the second dehydration is 600°C to 700°C to obtain a lithium oxide raw material; wherein, during the second dehydration process, the gas pressure in the reactor 100 is monitored, and when the gas pressure is greater than the first preset gas pressure, the second dehydration temperature is lowered, and when the gas pressure is less than the second preset gas pressure, the second dehydration temperature is increased. After the first dehydration preset time, the substance in the reactor 100 is mainly anhydrous lithium hydroxide, and S103 is a second dehydration of the anhydrous lithium oxide obtained by the first dehydration and the anhydrous lithium oxide in the original lithium hydroxide raw material, and this process is a process in which the anhydrous lithium oxide reacts to lithium oxide. S103 is performed under the condition of 600°C to 700°C, for example, S103 can be performed under the conditions of 600°C, 620°C, 640°C, 680°C and 700°C. This process will generate water vapor. When the reaction speed of the second dehydration is accelerated, the water vapor generated per unit time will also increase. The capacity of the preset vacuum pump is not enough to discharge the increased water vapor in time to stabilize the air pressure in the reactor 100. The accumulation of water vapor will increase the air pressure in the reactor 100. When the air pressure in the reactor 100 reaches the saturated vapor pressure, the reaction in the reactor 100 will stop. The reactor 100 is equipped with a temperature sensor and a pressure sensor, and the air pressure in the reactor 100 is detected by a barometer to make the air pressure in the reactor 100 suitable for the reaction.

[0046] The present application sets a detection device to monitor the gas pressure in the above-mentioned reactor 100. When the reactor 100 is at a certain temperature, after the gas pressure in the reactor 100 reaches a certain value, if the gas pressure continues to rise, the reaction tends to stop, and this gas pressure is recorded as the first preset gas pressure. When the detection device detects that the gas pressure in the furnace is greater than the first preset gas pressure, the temperature in the reactor 100 is reduced to reduce the rate at which lithium hydroxide in the reactor 100 is converted into lithium oxide, so that the water vapor generated by the reaction per unit time is reduced. At this time, according to the capacity of the vacuum pump of the reactor 100, the amount of water vapor discharged by the vacuum pump per unit time in the reactor 100 is greater than the amount of water vapor generated in the reactor 100 per unit time, so the pressure in the reactor 100 will be reduced, so that the reaction continues. When the gas pressure in the reactor 100 is reduced to the gas pressure before the temperature is raised, if the reactor 100 is kept at a lower temperature, the reaction rate will be reduced. The gas pressure in the reaction furnace 100 before the temperature is raised is referred to as the second preset gas pressure. When it is detected that the gas pressure in the reaction furnace 100 decreases from a value close to the first gas pressure to a value close to the second gas pressure or when the gas pressure in the reaction furnace 100 is less than the second preset gas pressure, the temperature provided to the reaction furnace 100 is increased to allow the reaction in the reaction furnace 100 to proceed at a high speed.

[0047] By adjusting the gas pressure of the reactor 100 in the manner of the present application, it is possible to ensure that the reaction of lithium hydroxide into lithium oxide in the reactor 100 continues, and the reaction is always carried out at a high speed at a relatively high temperature (and at this temperature, the gas pressure in the reactor 100 will not increase and the reaction will not stop). Therefore, the lithium oxide obtained according to the expected time has an ideal purity. Compared with the prior art in which the reaction temperature is increased to increase the reaction rate, the purity of the lithium oxide obtained at the expected time does not reach the expected target. The present solution timely adjusts the pressure in the reactor 100, so that the reaction in the reactor 100 continues within the expected time and is carried out at a pre-planned reaction speed. When the expected time is reached, the lithium oxide obtained at the expected time is taken out to test its purity, and it can be found that the lithium oxide reacted according to the expected time has the expected purity. That is, the solution of the present application can obtain lithium oxide of target purity while increasing the reaction temperature to increase the lithium oxide production rate, thereby making the production efficiency of lithium oxide higher.

[0048] The purity of lithium oxide produced by the method of the present application can reach 99.6-99.8%, while the purity of the original process is only 86-90%. The purity of lithium oxide produced by the method of the present application is significantly improved.

[0049] Reference Figure 2 The reaction furnace 100 mentioned in the present invention includes a vacuum exhaust pipe 110 , a crucible vacuum detection sensor 120 , a lithium hydroxide dehydration furnace 130 , and a vacuum pump 140 .

[0050] The reactor 100 of the present application includes a temperature sensor and a pressure sensor. The temperature sensor of the present solution is used to detect the temperature in the reactor 100, so as to timely adjust the temperature of the reaction, and ensure that the reaction is carried out continuously and at a high speed at a reasonable temperature. The pressure sensor of the present solution is used in conjunction with the pressure measuring instrument, so that the operator can intuitively obtain the pressure information in the reactor 100, and timely adjust the temperature of the reactor 100 with reference to the first preset air pressure and the second preset air pressure, so that the reaction in the reactor 100 continues.

[0051] As an embodiment of the present application, the present application can adopt a 550W-8L portable air pump and an 800-30L oil-free silent air pump, which can efficiently dissipate heat and add silent transfer equipment. Due to the characteristics of small body and oil-free, the 550W-8L portable air pump and the 800-30L oil-free silent air pump do not require frequent maintenance.

[0052] For the above-mentioned first preset air pressure and second preset air pressure, it can be understood that the first preset air pressure is 900Pa-1100Pa, and the second preset air pressure is 500Pa-700Pa. The first preset air pressure can be set to 900Pa, 1000Pa or 1100Pa. When it is detected that the air pressure in the reactor 100 reaches or exceeds 1000Pa, the temperature of the second dehydration is reduced. Such an adjustment method allows the reaction in the reactor 100 to continue, ensuring the purity of the lithium oxide produced under high temperature conditions, that is, such an adjustment method not only increases the rate of the second dehydration, but also ensures the purity of the lithium oxide obtained by the second dehydration.

[0053] The second preset air pressure can be set to 500Pa, 600Pa or 700Pa. When it is detected that the air pressure in the reactor 100 reaches or is less than 600Pa, the second dehydration temperature is increased. The second preset air pressure is the air pressure in the reactor 100 before the temperature is increased for the second dehydration. If a lower temperature is provided to the reactor 100, the reaction rate will decrease. When the air pressure in the reactor 100 reaches or is less than 600Pa, increasing the second dehydration temperature can allow the second dehydration to continue at a relatively high temperature, thereby increasing the reaction rate.

[0054] Of course, it can be understood that in some other embodiments, specifically, a third preset air pressure can be set, and the third preset air pressure is a value close to the first preset air pressure and less than the first preset air pressure. For example, the third preset air pressure can be set to 900 Pa. When it is detected that the air pressure in the reactor 100 reaches the third preset air pressure, the temperature of the second dehydration is slowly reduced. If it is detected that the air pressure in the reactor 100 reaches 1000 Pa of the first preset air pressure after a period of time, the cooling of the second dehydration is accelerated. By setting the third preset air pressure, the adjustment of the temperature of the second dehydration is gentler. This step-by-step adjustment avoids the instability of the second dehydration due to the large temperature change in a short time, and provides a more stable and gentle environment for the second dehydration.

[0055] Of course, it can be understood that in some other embodiments, specifically, a fourth preset air pressure can be set, and the fourth preset air pressure is a value close to the second preset air pressure and greater than the second preset air pressure. For example, the second preset air pressure can be set to 700 Pa. When it is detected that the air pressure in the reactor 100 reaches the fourth preset air pressure, the temperature of the second dehydration is slowly increased. If it is detected that the air pressure in the reactor 100 reaches 600 Pa of the second preset air pressure after a period of time, the temperature increase of the second dehydration is accelerated. By setting the fourth preset air pressure, the temperature adjustment of the second dehydration is gentler. Setting the fourth preset air pressure can increase the temperature in advance, ensuring that the second dehydration reacts at the maximum temperature allowed for the reaction under the current air pressure, further optimizing the process of the second dehydration, and further improving the rate of the second dehydration.

[0056] Of course, it is understandable that multiple preset air pressures can be set to further ensure that the second dehydration is basically carried out at the maximum temperature allowed for the reaction under the current air pressure, and the temperature control process of the second dehydration is gentler, improving the stability of the environment of the second dehydration, which is conducive to maintaining the safety and continuous progress of the reaction. In addition, setting multiple preset air pressures realizes the automation of temperature adjustment, reduces manual operation during the temperature adjustment process, and makes production efficiency higher.

[0057] In the prior art, lithium oxide is combined with a catalyst 340 to enter the electrolyte to promote the release of lithium ions. However, due to the full-enclosed structure of lithium oxide and the catalyst 340, that is, lithium oxide wraps the full-enclosed surface of the catalyst 340, the release of lithium ions is too intense and the initial lithium replenishment amount cannot be controlled.

[0058] In order to control the rate at which lithium oxide releases lithium ions and ensure a smooth lithium replenishment process, the present solution uses the cooperation of the conveyor belt 210, the electrostatic film 220, the vibration module and the spraying mechanism 250 to coordinately distinguish the weight of lithium oxide particles, control the contact area between the catalyst 340 and the lithium oxide, and form a semi-enclosed structure with the catalyst 340 and the lithium oxide, that is, the catalyst 340 is attached to a portion of the surface of the lithium oxide.

[0059] The semi-enclosed structure in which the catalyst 340 is attached to a part of the surface of lithium oxide is more difficult to process than the fully-enclosed structure in which lithium oxide is attached to the entire surface of the catalyst 340 or the fully-enclosed structure in which the catalyst 340 is attached to the entire surface of lithium oxide. The method for preparing a lithium ion battery lithium supplement provided in this scheme also includes a method for processing the semi-enclosed structure, including the following steps:

[0060] The lithium oxide raw material is ground to form lithium oxide powder.

[0061] The lithium oxide powder is spread on the conveyor belt 210 and conveyed along the first direction. An electrostatic film 220 is set above the conveying path of the lithium oxide powder. Static electricity is introduced into the electrostatic film 220 to adsorb the lithium oxide powder on the conveyor belt 210, and the electrostatic film 220 is conveyed in the first direction.

[0062] A spraying mechanism 250 is provided in the transmission path of the electrostatic film 220 . The spraying mechanism 250 is provided downstream of the conveyor belt 210 . The spraying mechanism 250 sprays the catalyst 340 onto the lithium oxide powder on the electrostatic film 220 , so that the catalyst 340 covers the wall of the lithium oxide powder away from the electrostatic film 220 .

[0063] It is understood that the lithium oxide particles can be ground by extrusion grinding, meson grinding, fluid grinding, etc. The ground lithium oxide is used to combine with the catalyst 340 and release lithium ions in the electrolyte.

[0064] For the electrostatic film 220, the electrostatic film 220 can be electrified by setting positive and negative electrodes in the directions of the opposite ends of the electrostatic film 220. After being electrified, the electrostatic film 220 can adsorb powdered lithium oxide. And because the adsorption capacity of the electrostatic film 220 is related to the current passing through the electrostatic film 220, the adsorption capacity of the electrostatic film 220 can be adjusted by controlling the magnitude of the current passing through the electrostatic film 220. By controlling the magnitude of the current passing through the electrostatic film 220, the adsorption capacity of the electrostatic film 220 is controlled so that the lithium oxide powder of the electrostatic film 220 is basically only one layer.

[0065] If multiple layers of lithium oxide powder are adsorbed on the electrostatic film 220, the lithium oxide powder on the side away from the electrostatic film 220 will block part of the surface of the lithium oxide powder on the bottom layer near the electrostatic film 220, so that the lithium oxide powder on the side near the electrostatic film 220 is exposed to a reduced area, resulting in a reduction in the area for the catalyst 340 to attach to these lithium oxide powders, that is, the catalyst 340 sprayed by the spraying mechanism 250 is difficult to fully fit with the lithium oxide powder adsorbed on the electrostatic film 220. Only adsorbing a layer of lithium oxide powder can expose a sufficient area for the catalyst 340 to attach, which is conducive to the catalyst 340 sprayed by the spraying mechanism 250 to fully fit with the lithium oxide powder. The present application provides a vibration device 230 or reasonably reduces the current passed into the electrostatic film 220, so that the lithium oxide powder adsorbed on the electrostatic film 220 is basically only one layer.

[0066] In the above steps, refer to Figure 3 , the first direction of the conveyor belt 210 is the direction from where the lithium oxide powder is placed to the spraying mechanism 250. It should be noted that the upstream of the electrostatic film 220 is located above where the lithium oxide powder is placed, and the downstream of the electrostatic film 220 is located above the spraying mechanism 250, and the electrostatic film 220 is arranged horizontally. The first direction followed by the electrostatic film 220 during transmission is the same as the first direction of the conveyor belt 210, that is, the direction from where the lithium oxide powder is placed to the spraying mechanism 250. The electrostatic film 220 can be designed in a straight line. After the lithium oxide powder is adsorbed from the upstream of the conveyor belt, it moves to the downstream of the electrostatic film 220 under the action of the electrostatic film 220. The spraying mechanism 250 is set downstream of the electrostatic film 220, and the catalyst 340 is loaded in the spraying mechanism 250. When the lithium oxide powder upstream of the electrostatic film 220 is transmitted to the downstream of the electrostatic film 220, the spraying mechanism 250 sprays the catalyst 340. At this time, the sprayed catalyst adheres to the surface of the lithium oxide powder exposed on the electrostatic film 220, which provides a prerequisite for promoting the lithium supplement to release lithium ions during the charging process.

[0067] Of course, it is understandable that the electrostatic film 220 can also be a self-enclosed annular belt. After the lithium oxide powder is adsorbed from the upstream of the electrostatic film 220, it moves to the downstream of the electrostatic film 220 under the action of the electrostatic film 220. The spraying mechanism 250 loaded with the catalyst 340 sprays the lithium oxide powder downstream of the electrostatic film 220, so that the catalyst 340 adheres to the surface exposed by the lithium oxide powder. At this time, you can choose to shake off and collect the lithium oxide powder that adheres to the catalyst 340, or you can choose not to shake off and collect the lithium oxide powder that adheres to the catalyst 340 temporarily, so that these lithium oxide powders circulate with the electrostatic film 220. When these lithium oxide powders that have attached the catalyst 340 reach the range of action of the spraying mechanism 250 for the second time, the spraying mechanism 250 is allowed to spray these lithium oxide powders again. Such a cyclic spraying method ensures that the area exposed by the lithium oxide powder is fully attached to the catalyst 340. Of course, when using a catalyst 340 with lower adhesion, in order to ensure that the catalyst 340 is fully attached to the area exposed by the lithium oxide powder, it is also possible to circulate the spraying in this way for multiple times.

[0068] In order to make the position of lithium oxide powder adsorbed by the electrostatic film 220 more stable, pits are pressed on the electrostatic film 220 to limit the position of lithium oxide particles adsorbed on the electrostatic film 220, so as to reduce the possibility of lithium oxide particles being blown away when the spraying mechanism 250 is in action. In some embodiments, a machine is used to set a row of needles to press the electrostatic film 220 to obtain an electrostatic film 220 with pits.

[0069] In order to more economically and conveniently press the electrostatic film 220, in some embodiments of the present solution, specifically, before the step of spreading the mixed lithium oxide powder on the conveyor belt 210 and transmitting it along the first direction, the following steps are also included:

[0070] The molding powder is spread on the first surface wall of the electrostatic film 220 facing upward, wherein the particle size of the molding powder is 50 micrometers to 100 micrometers.

[0071] The first surface wall is rolled and pressed by a embossing roller, so that a plurality of pits are formed on the first surface wall.

[0072] The molding powder is removed, and the first surface wall of the electrostatic film 220 is arranged downward.

[0073] Static electricity is introduced into the static film 220, and the first surface wall is transported to the top of the conveyor belt.

[0074] The pressing rollers include a first pressing roller and a second pressing roller, the first pressing roller faces the first surface wall, and the second pressing roller is on the other side of the first surface wall. When the electrostatic film 220 carrying the pressing powder passes through the first pressing roller and the second pressing roller, a pit will be pressed out.

[0075] The particle size of the molding powder is 50 microns to 100 microns, for example, the particle size of the molding powder is 50 microns, 70 microns, 90 microns, and 100 microns, so the diameter of the pressed pit is 50 microns to 100 microns. For example, the molding powder with a particle size of 50 microns is pressed by the molding roller to form a pit with a diameter of substantially 50 microns on the first surface wall of the electrostatic film 220. The pit pressed by the molding powder is used to limit the position of the lithium oxide particles adsorbed on the electrostatic film 220, reducing the possibility of the lithium oxide particles being blown away when the spraying mechanism 250 acts later.

[0076] It should be noted that the pits of the electrostatic film 220 can accommodate more than one lithium oxide particle. After being acted upon by the vibration device 230, the lithium oxide particles are still arranged in a single layer and at intervals in the pits of the electrostatic film. This stabilizes the position of the lithium oxide particles and improves the utilization rate of the surface of the lithium oxide powder during the manufacture of the lithium supplement, thereby accelerating the rate at which the lithium oxide powder releases lithium ions. In addition, the bonding area between the lithium oxide powder and the catalyst 340 is relatively fixed, which is convenient for measurement.

[0077] In some embodiments of the present application, reference 2 and Figure 3 Before the step of spraying the catalyst 340 onto the lithium oxide powder on the electrostatic film 220, a vibration device 230 is arranged on the transmission path of the electrostatic film 220. The vibration device 230 is arranged on the side of the electrostatic film 220 away from the lithium oxide powder. Along the first direction, the vibration device 230 is arranged downstream of the conveyor belt 210 and upstream of the spraying mechanism. The vibration device 230 drives the electrostatic film 220 to vibrate.

[0078] If multiple layers of lithium oxide powder are adsorbed on the electrostatic film 220, the lithium oxide powder on the side away from the electrostatic film 220 will block part of the surface of the lithium oxide powder on the bottom layer near the electrostatic film 220, reducing the exposed area of ​​the lithium oxide powder near the electrostatic film 220, resulting in a reduced area for the catalyst 340 to attach to the lithium oxide powder, that is, it is difficult for the catalyst 340 sprayed by the spraying mechanism 250 to fully fit with the lithium oxide powder adsorbed on the electrostatic film 220. However, if only one layer of lithium oxide powder is adsorbed, the lithium oxide powder adsorbed on the electrostatic film 220 can be exposed to a sufficient area for the catalyst 340 to attach, which is conducive to the catalyst 340 sprayed by the spraying mechanism 250 to fully fit with the lithium oxide powder.

[0079] The vibrating device 230 is provided to shake off the lithium oxide powder that is not firmly adsorbed on the electrostatic film 220, and the shaken lithium oxide powder falls into the collecting device 240. The lithium oxide powder that is not firmly adsorbed here includes the lithium oxide powder that is stacked on other lithium oxide powders due to the adsorption of the electrostatic film 220. The vibrating device 230 is provided to shake off the lithium oxide powder that is stacked on other lithium oxide powders due to the adsorption of the electrostatic film 220, further ensuring the single-layer arrangement of the lithium oxide powder on the electrostatic film 220, exposing the lithium oxide powder adsorbed on the electrostatic film 220 to a sufficient area for the catalyst 340 to adhere, which is conducive to the catalyst 340 sprayed by the spraying mechanism 250 to fully adhere to the lithium oxide powder.

[0080] It can be understood that the vibration device 230 used in the present application can use mechanical vibration to shake off the lithium oxide powder on the electrostatic film 220 that is stacked on other lithium oxide powders due to the adsorption of the electrostatic film 220. The vibration device 230 of the present application can also use sound wave vibration through the air to shake off the lithium oxide powder on the electrostatic film 220 that is stacked on other lithium oxide powders due to the adsorption of the electrostatic film 220.

[0081] Of course, in some other embodiments of the present application, specifically, the current passing through the electrostatic film 220 can be weakened to reduce the adsorption force of the electrostatic film 220, so that the lithium oxide powder stacked on other lithium oxide powders on the electrostatic film 220 due to the adsorption of the electrostatic film 220 can fall down, thereby further ensuring the single-layer arrangement of the lithium oxide powder on the electrostatic film 220, and exposing the lithium oxide powder adsorbed on the electrostatic film 220 to a sufficient area for the catalyst 340 to adhere, which is beneficial for the catalyst 340 sprayed out by the spraying mechanism 250 to fully adhere to the lithium oxide powder.

[0082] In some embodiments of the present application, specifically, after the step of driving the electrostatic film 220 to vibrate by the vibration device 230 and before the step of spraying the catalyst 340 onto the lithium oxide powder on the electrostatic film 220, the portion of the electrostatic film 220 located downstream of the vibration device 230 is turned over so that the lithium oxide powder is placed above the electrostatic film 220.

[0083] The upstream of the electrostatic film 220 is located above the lithium oxide powder placement area, and the downstream of the electrostatic film 220 is located below the spraying mechanism 250. The surface of the electrostatic film 220 upstream facing the lithium oxide powder placement area adsorbs lithium oxide powder. In this embodiment, after the surface adsorbs lithium oxide powder, it passes through the vibration device 230 and twists to the direction facing the spraying mechanism 250 near the spraying mechanism 250, that is, the surface twists from the direction facing the lithium oxide powder placement area to the direction away from the lithium oxide powder placement area, and the surface twists from the lower side of the electrostatic film 220 to the upper side. Since the surface adsorbs lithium oxide powder, the surface is located on the upper side of the electrostatic film 220, and the spraying mechanism 250 loaded with the catalyst 340 is located on the upper side of the conveyor belt.

[0084] With the transmission mechanism thus arranged, the spraying mechanism 250 can spray the catalyst 340 with a smaller power than when it is arranged below the electrostatic film 220. The sprayed catalyst 340 falls to the exposed surface of the lithium oxide powder adsorbed on the surface of the electrostatic film 220 under the action of gravity and adheres to the lithium oxide powder. This arrangement can prevent the spraying mechanism 250 from blowing away the lithium oxide powder adsorbed on the electrostatic film 220 due to excessive power when spraying the catalyst 340, making the entire processing process of the lithium oxide powder more stable, reducing the waste of lithium oxide powder and the catalyst 340, and saving production costs.

[0085] The catalyst 340 mentioned herein is used to catalyze the decomposition of lithium oxide to release active lithium. Of course, the catalyst 340 can also be used to catalyze at least one of lithium peroxide, lithium fluoride, lithium carbonate, lithium oxalate and lithium acetate to release active lithium.

[0086] This solution may also use at least one of lithium peroxide, lithium fluoride, lithium carbonate, lithium oxalate and lithium acetate, which are materials rich in lithium ions, to replace the lithium oxide of the above-mentioned lithium supplement. In some embodiments of the present application, the above-mentioned lithium ion-rich materials may include at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobaltate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminumate, etc., but are not limited thereto. Among them, lithium nickelate, lithium nickel cobalt manganate, and lithium nickel cobalt aluminumate usually have a layered crystal structure, lithium manganate has a spinel structure, and lithium cobaltate and lithium nickel manganate may be layered and / or spinel structures. Among them, the general structural formula of lithium cobaltate, lithium manganate, and lithium nickelate may be any one of LiMO2, Li2MO2, Li2MO3, Li2MO4, Li3MO4, Li5MO4, and Li6MO4, and M may represent Ni, Co or Mn.

[0087] In some other embodiments of the present application, the above-mentioned lithium ion-rich material may also contain doping elements. The doping elements may include at least one of B, P, N, Mg, Al, Ca, Ba, La, Zr, Mo, Nb, Ti, V, Sn, Sb, Cr, Fe, Cu and Zn. Among them, it is best that the nickel cobalt oxide does not contain the doping element Al to avoid overlap with the nickel cobalt aluminum oxide ternary material. By introducing appropriate doping elements, it is possible to change at least one of the intrinsic electron orbital overlap, surface properties, and improved structural stability of the above-mentioned lithium ion-rich material.

[0088] The catalyst 340 used in the lithium supplement agent of the present application is an oxide-type positive electrode active material with special XRD properties, which has good catalytic activity and can catalyze the lithium ion-rich materials with high delithiation potential to decompose and release active lithium ions at a lower potential during the formation stage of the battery, enriching the selection range of lithium supplement agents. The lithium supplement agent has a high lithium supplement capacity and can better supplement the irreversible consumption of active lithium by the battery, which is beneficial to the improvement of battery performance. In addition, the lithium supplement agent has less residue left on the positive electrode side after delithiation, and will not increase the risk of electrolyte gas production, will not increase the impedance of the battery cell, and will not reduce the energy density of the battery.

[0089] In the embodiment of the present application, the particle size of the catalyst 340 is 30 nm-10 μm. The particle size of the catalyst 340 can be selected according to the electrochemical activity of the lithium-rich material. For example, when the electrochemical activity of the lithium-rich material is low, a catalyst 340 with a smaller particle size is more conducive to its decomposition.

[0090] In the embodiment of the present application, the mass ratio of the lithium-rich material to the catalyst 340 can be 1:(0.01-80). In some embodiments, the mass ratio can be 1:(0.1-15). In other embodiments, the mass ratio can be 1:(0.5-15). In some other embodiments, the mass ratio of the lithium-rich material to the catalyst 340 can be 1:(3-10). Controlling the ratio of the lithium-rich material to the catalyst 340 in an appropriate range can regulate the initial lithium de-lithiation capacity, the actual lithium supplement capacity, etc. of the lithium supplement. In some embodiments of the present application, the initial lithium de-lithiation capacity of the lithium supplement can be freely matched within the range of 400-1800mAh / g. In some embodiments, the initial lithium de-lithiation capacity of the lithium supplement can be within the range of 420-1500mAh / g, and in other embodiments, the value can be adjusted within the range of 420-610mAh / g. For example, when the lithium-rich material is lithium oxide, when the mass ratio of lithium oxide to the catalyst 340 is greater than or equal to 1:3, the initial lithium de-lithiation capacity of the lithium supplement can be above 400mAh / g.

[0091] The lithium supplement agent provided in the embodiments of the present application has high structural stability and good safety performance. It can efficiently release active lithium under the normal operating voltage of the battery (not exceeding 4.2V), has a high lithium supplement capacity, and its de-lithium residue will not increase the risk of electrolyte gas production, will not increase the impedance of the battery cell, and will help to improve the cycle performance and energy density of the battery. The battery term "battery energy density" refers to the amount of electricity stored in a battery per unit weight or volume. The battery energy density can be obtained by multiplying the specific capacity of the electrode material by the discharge voltage. This value is essentially equal to the amount of active lithium divided by the volume or mass of the entire battery. The greater the lithium supplement capacity provided by the lithium supplement agent, the less the mass of the residue after lithium supplementation, and the greater the improvement in the energy density of the battery.

[0092] It is understandable that according to some embodiments of the present application, after the step of spraying the catalyst 340 onto the lithium oxide powder on the electrostatic film 220, the lithium oxide powder mixture after the catalyst spraying is sintered under an inert gas and then ball-milled at a low speed to obtain a lithium supplement.

[0093] Preferably, in some embodiments of the present application, the final lithium-supplementing material, that is, the lithium oxide obtained in the above steps, is first subjected to high-energy ball milling, which can destroy its original structure, realize its lattice reconstruction, mix the lithium atoms and the transition metal atoms, expose certain crystal planes, and have a strong catalytic activity of the lithium-rich material. The oxide-type active material is mixed with the lithium-rich material and then subjected to high-energy ball milling together. At this time, the lattice reconstruction of the oxide-type positive electrode active material and the coating and / or dispersion of the lithium-rich material can be realized simultaneously.

[0094] In some embodiments of the present application, the rotation speed of the high energy ball milling is above 400r / min. In some embodiments, the rotation speed of the high energy ball milling can be above 500r / min, for example, it can be 500-1300r / min or 700-900r / min. In some embodiments of the present application, the ball to material ratio during high energy ball milling can be in the range of (10-40):1. A higher ball to material ratio can better achieve lattice reconstruction. In some embodiments, the ball to material ratio during high energy ball milling can be in the range of (5-30):1.

[0095] In this embodiment, the fusion of the catalyst 340 and the lithium oxide is carried out by physical fusion. The above-mentioned physical fusion method can be ball milling, sand milling or coating. In one embodiment of the present application, the physical fusion method can be low-speed ball milling, and its rotation speed is lower than the rotation speed of the above-mentioned high-energy ball milling. After obtaining the catalyst 340, the catalyst 340 and the lithium oxide are subjected to low-speed ball milling to avoid destroying the lattice structure of the catalyst 340 formed above.

[0096] In some embodiments of the present application, the rotation speed of the low-speed ball mill is less than or equal to 400r / min. For example, it can be 300-400r / min or 300-350r / min. In some embodiments, the rotation speed of the low-speed ball mill can be below 350r / min. In some embodiments of the present application, the low-speed ball milling is carried out at a lower ball-to-material ratio. For example, the ball-to-material ratio during low-speed ball milling can be in the range of (1.5-8):1. In some embodiments of the present application, the diameter of the grinding balls used in the low-speed ball milling is ≤8mm.

[0097] Regarding the sintering in the above steps, firstly, raw materials are prepared, the mass fraction of the lithium inorganic salt compound is 40-99%, the mass fraction of the catalyst 340 is 1-40%, and the mass fraction of the conductive agent is 1-35%. Next, the lithium inorganic salt compound and the catalyst 340 are moved to a sintering furnace, a gaseous carbon source is introduced into the sintering furnace, and carbon is coated on the surface of the lithium inorganic salt compound and the catalyst 340 by chemical vapor deposition to prepare a composite lithium supplement.

[0098] The sintering can be carried out in air, and the sintering temperature can be 600-1200° C., for example, 800-900° C. The sintering time can be 6-24 hours, for example, 8-15 hours. A higher sintering temperature and a longer sintering time are more conducive to the re-growth of lithium oxide, thereby obtaining a lithium oxide material with high crystallinity.

[0099] In some embodiments of the present application, the lithium supplement agent further includes a protective layer that wraps the catalyst 340 and the lithium-rich material, and the protective layer has ionic conductivity. The protective layer can further improve the stability and processing performance of the positive electrode lithium supplement agent, especially when the lithium-rich material is lithium oxide or lithium peroxide.

[0100] In an embodiment of the present application, the lithium supplement may further include a protective layer, which wraps the catalyst 340 and lithium oxide. The material of the protective layer includes at least one of lithium fluoride, lithium carbonate, lithium oxalate, lithium acetate, lithium phosphate, inorganic conductive carbon, organic polymers and inert oxides. These protective layers do not increase the risk of gas production of the battery electrolyte. In an embodiment of the present application, the thickness of the protective layer is 3nm-150nm. The appropriate thickness of the protective layer can not only ensure that the positive electrode lithium supplement has good processing performance, but also avoid excessive thickness affecting the timely release of active lithium and increasing battery impedance.

[0101] Lithium oxide has a high stability in air, and may or may not have a protective layer. When there is no protective layer in the lithium supplement, lithium oxide is preferably used to coat the surface of the catalyst 340. In particular, when lithium oxide and / or lithium peroxide are used as lithium supplement materials, the presence of a protective layer can make the lithium supplement have better processing performance and structural stability.

[0102] Specifically, the lithium supplement agent is a core-shell structure, including a core and a protective layer wrapping the core, and the core includes a catalyst 340 and lithium oxide. In the core, the catalyst 340 is attached to part of the surface of the lithium oxide particles. Due to the presence of the protective layer, the catalyst 340 and the lithium oxide are basically not in contact with the air, and the lithium supplement ability will not deteriorate due to the absorption of moisture, carbon dioxide, oxygen, etc. in the air, which can further improve the stability of the lithium supplement agent. In addition, compared with the lithium-rich materials such as Li2NiO2 and Li6CoO4 in the prior art, the chemical activity of the lithium-rich materials here is not high, and the structural stability of itself is higher. Moreover, the presence of the protective layer prevents the lithium-rich material from directly contacting the positive electrode slurry when it has a high alkalinity, so that the processing performance of the lithium supplement agent is good, and it can be better compatible with the existing manufacturing process of the positive electrode of the lithium-ion battery, and will not reduce the fluidity of the positive electrode slurry and will not affect the coating effect.

[0103] The electrolyte is a mixed solution of 1.2 mol / L lithium hexafluorophosphate dissolved in ethylene carbonate and dimethyl carbonate in an equal volume ratio.

[0104] In order to further optimize the preparation of the lithium supplement, the preparation method of the lithium supplement for lithium ion batteries of the present application further includes the following steps:

[0105] The raw material of lithium oxide is ground into two batches, the volume of the first batch of lithium oxide powder 320 is larger than the volume of the second batch of lithium oxide powder 330, and the two batches of powder are evenly mixed;

[0106] The mixed lithium oxide powder is spread on the conveyor belt 210 and conveyed along the first direction. An electrostatic film 220 is arranged above the conveying path of the lithium oxide powder. Static electricity is introduced to the electrostatic film 220 to adsorb the lithium oxide powder on the conveyor belt 210. The electrostatic film 220 is conveyed in the first direction.

[0107] The first batch of lithium oxide powder 320 on the electrostatic film 220 is separated from the electrostatic film 220 by vibration or static reduction;

[0108] A spraying mechanism 250 is arranged in the transmission path of the electrostatic film 220 and is arranged downstream of the conveyor belt 210. The spraying mechanism 250 sprays the catalyst 340 onto the lithium oxide powder on the electrostatic film 220 so that the catalyst 340 covers the wall of the second batch of lithium oxide powder 330 facing away from the electrostatic film 220.

[0109] Reference Figure 4, processing lithium oxide powders of different volumes, the first batch of lithium oxide powders 320 and the second batch of lithium oxide powders 330 can be adsorbed by the electrostatic film 220 when they are transported to the placement by the conveyor belt 210, and when the electrostatic film 220 transports the first batch of lithium oxide powders 320 and the second batch of lithium oxide powders 330 to the vibration device 230, the first batch of lithium oxide powders 320 will be shaken off under the action of the vibration device 230. Since the first batch of lithium oxide powders 320 and the second batch of lithium oxide powders 330 are mixed and adsorbed by the electrostatic film 220, after the first batch of lithium oxide powders 320 are shaken off, a structure in which the second batch of lithium oxide powders 330 are arranged alternately on the electrostatic film 220 will be formed.

[0110] The lithium oxide on the electrostatic film 220 is arranged at intervals to provide more area for the catalyst 340 to attach, so that the catalyst 340 is fully attached to the surface of the lithium oxide. In addition, from a macroscopic point of view, the lithium oxide powder adsorbed on the electrostatic film 220 is evenly arranged at intervals, and the interval arrangement ensures that the area of ​​the catalyst 340 attached to each lithium oxide is the same, so that the amount of the catalyst 340 combined with the lithium oxide is relatively quantitative (if the lithium oxide powders are adhered to each other, the surface area of ​​the lithium oxide powder for the catalyst 340 to attach is uncertain, and the amount of the catalyst 340 attached to the lithium oxide cannot be determined), which is convenient for control and conducive to the control of the subsequent reaction process.

[0111] In some embodiments of the present application, the weight of the first batch of lithium oxide powder 320 is between 3 and 10 times the weight of the second batch of lithium oxide powder 330. For example, the weight of the first batch of lithium oxide powder 320 is 5 times the weight of the second batch of lithium oxide powder 330 or the weight of the first batch of lithium oxide powder 320 is 7 times the weight of the second batch of lithium oxide powder 330. Distinguishing the weight of the first batch of lithium oxide powder 320 from the weight of the second batch of lithium oxide powder 330 facilitates the vibration device 230 to shake off the first batch of lithium oxide powder 320 according to the expected effect.

[0112] According to the above-mentioned method for preparing the lithium supplement, the present application also provides a lithium supplement for lithium ion batteries containing lithium oxide, which is used to reduce the reduction in battery capacity caused by the irreversible capacity of the battery during the initial charge and discharge and cycle process. Figure 5 According to the lithium supplement obtained by the above method, the lithium supplement for lithium-ion batteries includes lithium supplement particles, the lithium supplement particles include a catalyst 340 and lithium oxide, and the catalyst 340 is half-enclosed in the lithium oxide. The catalyst 340 is half-enclosed in the lithium oxide, so that the lithium supplement can continuously and smoothly release lithium ions during the first charging process of the battery.

[0113] It is understood that, according to the lithium supplement agent obtained by the above method, the particle size of the lithium supplement particles ranges from 80 nanometers to 20,000 nanometers, and the mass of lithium oxide in the lithium supplement particles is between 1 and 10 times the mass of the catalyst 340. For example, the particle size of the lithium supplement agent is 80 nanometers, 600 nanometers, 1 micrometer, 10 micrometers or 20,000 nanometers, and the mass of lithium oxide in the lithium supplement particles is 1, 4, 7 or 10 times the mass of the catalyst 340. The lithium supplement agent configured in this way is convenient to process, and has a stable structure and is easy to react.

[0114] Of course, it is understood that the diameter of the lithium oxide particles prepared according to this solution is between 50 nanometers and 10 micrometers. For example, the diameter of the lithium oxide particles prepared according to this solution can be 50 nanometers, 500 nanometers, 1 micrometer, 6 micrometers or 10 micrometers. The lithium oxide particles arranged in this way are convenient to process, and the structure is stable and easy to react.

[0115] In summary, the present application provides a specific embodiment of a method for preparing a lithium ion battery lithium supplement, comprising the following steps:

[0116] Step 1: placing lithium hydroxide raw material in a reaction furnace 100 for primary dehydration, wherein the primary dehydration temperature ranges from 150°C to 200°C.

[0117] Step 2: After the first preset time of the first dehydration, a second dehydration is performed, and the temperature range of the second dehydration is 400°C to 600°C to obtain a lithium oxide raw material; wherein, during the second dehydration process, the gas pressure in the reactor 100 is monitored. A first preset gas pressure and a third preset gas pressure close to and less than the first preset gas pressure are set, and a second preset gas pressure and a fourth preset gas pressure close to and greater than the second preset gas pressure are set. The first preset gas pressure is the gas pressure at which the reaction tends to stop if the gas pressure continues to rise after the gas pressure in the reactor 100 reaches a certain value when the reactor 100 is at a certain temperature; the second preset gas pressure is the gas pressure before the reactor 100 is heated up. When the detected gas pressure of the reactor 100 is greater than the third preset gas pressure, the secondary dehydration temperature is slowly lowered. If the gas pressure in the reactor 100 is still rising at this time, when it is detected that the gas pressure in the reactor 100 is close to the first preset gas pressure, the temperature in the reactor 100 is greatly reduced. When the detected gas pressure in the reactor 100 is less than the fourth preset gas pressure, the secondary dehydration temperature is slowly increased. If the gas pressure in the reactor 100 is still decreasing at this time, when it is detected that the gas pressure in the reactor 100 is close to the second preset gas pressure, the temperature in the reactor 100 is greatly increased.

[0118] Step 3: Use a pressing roller and pressing powder to press pits on the first surface wall of the electrostatic film 220.

[0119] Step 4: Grind the raw material of lithium oxide obtained in the above steps into two batches. The volume of the first batch of lithium oxide powder 320 is larger than that of the second batch of lithium oxide powder 330. The two batches of powder are evenly mixed.

[0120] Step 5: High-energy ball milling is performed on the lithium oxide raw material, wherein the ball-to-material ratio during high-energy ball milling is 30:1 and the rotation speed of the high-energy ball mill is 1000 r / min.

[0121] Step 6: Spread the mixed lithium oxide powder on the conveyor belt 210 and transport it along the first direction. Set an electrostatic film 220 above the transmission path of the lithium oxide powder, introduce static electricity to the electrostatic film 220 to adsorb the lithium oxide powder on the conveyor belt 210, and the electrostatic film 220 is transported in the first direction. Wherein, a vibration device 230 is set downstream of the electrostatic film 220, and the vibration device 230 uses a sound wave to vibrate in the air to shake off the first batch of lithium oxide powder 320. The upstream of the electrostatic film 220 adsorbs lithium oxide on the surface of the conveyor belt 210, and the surface of the electrostatic film 220 upstream for adsorbing lithium oxide powder is located at the lower side of the electrostatic film 220. After passing through the vibration device 230, the part of the electrostatic film 220 located downstream of the vibration device 230 is turned over, so that the surface adsorbing lithium oxide powder is placed on the upper side of the electrostatic film 220, and a spraying structure for loading catalyst 340 is set downstream of the electrostatic film 220, and the spraying mechanism 250 is located above the electrostatic film 220.

[0122] Step 7: The spraying mechanism 250 sprays the lithium oxide. The spraying mechanism 250 uses a tiny power to spray the catalyst 340, so that the catalyst 340 is scattered on the exposed surface of the lithium oxide powder under the action of gravity.

[0123] Step 8: The lithium oxide powder mixture after spraying the catalyst is sintered under inert gas at a sintering temperature of 800° C. for 7 hours. The mass fraction of lithium oxide used in this sintering process is 60%, the mass fraction of catalyst 340 is 15%, and the mass fraction of the conductive agent is 25%.

[0124] Step 9: The combination of the sintered lithium oxide powder and the catalyst 340 is subjected to low-speed ball milling. The rotation speed of the low-speed ball mill is 320 r / min, the ball-to-material ratio during the low-speed ball milling is 6:1, and the diameter of the grinding balls used in the low-speed ball milling is 4 mm.

[0125] Step 10: Next, the lithium oxide and the catalyst 340 are moved to the sintering furnace again, and a gaseous carbon source is introduced into the sintering furnace. Carbon is coated on the surface of the lithium oxide and the catalyst 340 by chemical vapor deposition. This carbon layer serves as a protective layer of the lithium supplement and has a thickness of 80 nm. The final lithium supplement is prepared.

[0126] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a lithium-ion battery lithium supplement containing lithium oxide, characterized in that: The following steps are involved: The lithium hydroxide raw material is placed in a reaction furnace for primary dehydration, and the primary dehydration temperature ranges from 150° C. to 200° C.; After the first preset time of the first dehydration, a secondary dehydration is performed, and the secondary dehydration temperature ranges from 600° C. to 700° C., so as to obtain a lithium oxide raw material; wherein, during the secondary dehydration process, the gas pressure in the reaction furnace is monitored, and when the gas pressure in the reaction furnace is greater than the first preset pressure, the secondary dehydration temperature is lowered, and when the gas pressure is less than the second preset pressure, the secondary dehydration temperature is increased; Grinding the lithium oxide raw material to form lithium oxide powder, and spraying a catalyst onto the lithium oxide powder; The lithium oxide powder mixture after the catalyst is sprayed is sintered under an inert gas and then ball-milled at a low speed to obtain a lithium supplement.

2. The method for preparing a lithium supplement for lithium ion batteries containing lithium oxide according to claim 1, characterized in that: The first preset air pressure is 900Pa-1100Pa, and the second preset air pressure is 500Pa-700Pa.

3. The method for preparing a lithium-ion battery lithium supplement containing lithium oxide according to claim 1, characterized in that: The step of grinding the lithium oxide raw material to form lithium oxide powder and spraying a catalyst onto the lithium oxide powder comprises the following steps: Grinding the lithium oxide raw material to form lithium oxide powder; The lithium oxide powder is spread on a conveyor belt and conveyed along a first direction, an electrostatic film is arranged above the conveying path of the lithium oxide powder, static electricity is introduced to the electrostatic film to adsorb the lithium oxide powder on the conveyor belt, and the electrostatic film is conveyed toward the first direction; A spraying mechanism is arranged in the transmission path of the electrostatic film, and the spraying mechanism is arranged downstream of the conveyor belt. The spraying mechanism sprays catalyst onto the lithium oxide powder on the electrostatic film so that the catalyst covers the wall surface of the lithium oxide powder away from the electrostatic film.

4. The method for preparing a lithium-ion battery lithium supplement containing lithium oxide according to claim 3, characterized in that: Before the step of spraying the catalyst onto the lithium oxide powder on the electrostatic film, the following steps are also included: A vibration device is arranged on the transmission path of the electrostatic film. The vibration device is arranged on the side of the electrostatic film away from the lithium oxide powder. Along the first direction, the vibration device is arranged downstream of the conveyor belt and upstream of the spraying mechanism. The vibration device drives the electrostatic film to vibrate.

5. The method for preparing a lithium supplement for lithium ion batteries containing lithium oxide according to claim 4, characterized in that: After the step of driving the electrostatic film to vibrate by the vibration device and before the step of spraying a catalyst onto the lithium oxide powder on the electrostatic film, the following steps are also included: The portion of the electrostatic film located downstream of the vibration device is turned over so that the lithium oxide powder is placed above the electrostatic film.

6. The method for preparing a lithium supplement for lithium ion batteries containing lithium oxide according to claim 4, characterized in that: The vibration device is capable of generating sound waves, and the sound waves drive the electrostatic membrane to vibrate.

7. A lithium-ion battery lithium supplement containing lithium oxide produced by the preparation method according to any one of claims 1 to 6, characterized in that: The lithium supplement for lithium-ion batteries containing lithium oxide comprises lithium supplement particles, wherein the lithium supplement particles comprise a catalyst and lithium oxide, and the catalyst is half-enclosed in the lithium oxide.

8. The lithium supplement for lithium ion batteries containing lithium oxide according to claim 7, characterized in that: The particle size of the lithium supplement particles ranges from 80 nanometers to 20,000 nanometers.

9. The lithium supplement for lithium ion batteries containing lithium oxide according to claim 8, characterized in that: The mass of lithium oxide in the lithium-supplementing particles is between 1 and 10 times the mass of the catalyst.

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