High-purity lithium oxide continuous production process and system based on DBD plasma technology

Abstract

The invention provides a high-purity lithium oxide continuous production process and system based on a DBD plasma technology, and belongs to the technical field of lithium battery material production. According to the invention, the problem of process fluctuation caused by easy moisture absorption and caking of lithium hydroxide can be effectively solved, a plasma activation effect and a controllable heat conduction technology are cooperated, and efficient decomposition of lithium hydroxide is realized under a low-temperature condition. The collaborative mechanism significantly reduces the energy input demand, shortens the reaction period, and thoroughly avoids the generation of impurities caused by high-temperature side reaction. The whole process is carried out under inert atmosphere protection, no chemical additive participates, a decomposition product is only water vapor and is recycled through a circulating system, an adopted waste heat integration system transfers cooling medium heat to a raw material pretreatment link, an energy closed loop is formed, and the overall energy consumption is remarkably reduced compared with a traditional process; and finally obtaining the high-purity single-phase lithium oxide.

Description

Technical Field

[0001] This invention relates to the field of lithium battery material production technology, and in particular to a continuous production process and system for high-purity lithium oxide based on DBD plasma technology. Background Technology

[0002] Lithium oxide, as a key precursor for high-performance lithium-ion battery solid electrolytes and high-nickel cathode materials, directly affects the battery's energy density and cycle life. Currently, industrial-grade lithium oxide production mainly employs high-temperature thermal decomposition methods using lithium carbonate or lithium hydroxide: the former requires decomposing lithium carbonate at 700-900℃, resulting in extremely high energy consumption and a tendency for lithium oxide sintering; while the latter, although its decomposition temperature is lowered to 450-600℃, still faces two major bottlenecks: firstly, the high-temperature environment leads to the formation of lithium peroxide impurities, making it difficult to achieve a product purity exceeding 99.5%; secondly, the water vapor and carbon dioxide released during the decomposition process require a corresponding exhaust gas treatment system, increasing environmental costs.

[0003] To reduce energy consumption, some studies have attempted to introduce plasma-assisted decomposition technology. Dielectric barrier discharge (DBD) plasma, as a typical non-equilibrium low-temperature plasma, generates glow discharge rich in high-energy electrons and active free radicals by placing an insulating dielectric layer between electrodes and applying a high-frequency, high-voltage electric field to ionize the gas. This technology has been applied in materials synthesis because it can activate molecular bonds at near-room temperature. However, existing DBD technology has significant drawbacks when processing solid powder materials: Poor discharge uniformity: Traditional parallel plate electrode structures are prone to electric field distortion at the powder accumulation interface, leading to local arc breakdown and damaging low-temperature characteristics; Water vapor interference: The moisture content of raw materials or water vapor generated in the reaction can reduce the dielectric strength of the gas and induce short circuits between electrodes; Continuous production barriers: The lack of integrated design in the automatic powder feeding, process monitoring and product collection links makes it difficult to adapt to industrial continuous production.

[0004] For lithium hydroxide feedstock, which is highly hygroscopic (hygroscopicity > 30%), existing technologies face the problem of process instability due to insufficient pretreatment—unremoved free water vaporizes in the plasma reactor, further exacerbating the risk of electric arcing. Although low-temperature plasma technology theoretically has the potential to lower the decomposition temperature, due to the aforementioned engineering bottlenecks, a reliable continuous production scheme for high-purity lithium oxide has not yet been found. Summary of the Invention

[0005] The purpose of this invention is to provide a continuous production process and system for high-purity lithium oxide based on DBD plasma technology. Lithium hydroxide is supported on the lower electrode plate of the plasma device, serving as both a dielectric layer and the material to be processed. Its solid-state insulation allows for the accumulation of charge to generate a reverse electric field, suppressing the electric arc and forming pulsed micro-discharges to maintain the non-equilibrium plasma state. High-energy electrons in the uniform glow between the positive and negative electrodes of the DBD plasma collide with LiOH, breaking the Li⁺-OH⁻ ionic bonds and significantly reducing the decomposition temperature. By utilizing the heat storage of plasma irradiation and the heat conduction of hot oil for synergistic thermal decomposition, high-purity lithium oxide is generated at lower temperatures and lower voltages. Only water vapor is emitted, with no polluting gas emissions. The process is simple, requires no solvents or catalysts, avoids the formation of lithium peroxide, and produces high-purity products.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: This invention provides a continuous production process for high-purity lithium oxide based on DBD plasma technology, comprising the following steps: (1) Input lithium hydroxide raw material into a pneumatic crushing and screening device and crush and screen it to a particle size ≤500μm; (2) Input the material obtained in step (1) into the pretreatment rotary kiln, remove free water under a slight negative pressure condition of vacuum degree -0.09~-0.07MPa and an inert atmosphere of temperature ≤105℃ to obtain dehydrated lithium hydroxide; (3) Dehydrated lithium hydroxide is transported to the DBD plasma device through a material storage bin and uniformly covered on the surface of the lower electrode plate by a material covering mechanism, with a material thickness of 1~30mm; (4) After evacuating the DBD plasma device to below 10⁻²Pa, introduce inert gas to maintain the pressure inside the cavity at 0.1Pa~1kPa; (5) Adjust the upper electrode of the DBD plasma device to descend to 35~100mm from the lower electrode, and apply a high-frequency sinusoidal power supply of 200~700V, 10~80kHz, and current density of 0.3~1A / cm² to generate glow. (6) Start the lower electrode plate to rotate at 4π~14π radians / minute, and at the same time, heat is supplied through the hot oil channel inside the lower electrode plate to maintain the material contact surface temperature at 200~450℃; (7) The reaction was stopped when the content of the exhaust gas was 0 by synergistic plasma irradiation and thermal decomposition for 30 to 360 minutes and monitored by a water vapor sensor. (8) Lithium oxide powder is extracted under negative pressure and cooled and packaged in an inert atmosphere cooling chamber.

[0007] Preferably, in step (1), the pneumatic crushing and screening process forms a high-speed vortex through tangential air intake, the crushing blades rotate in the opposite direction to the airflow vortex, and the filter screen controls the particle size to ≤500μm.

[0008] Preferably, in step (3), the fabric thickness is 5-25mm.

[0009] Preferably, it also includes a waste heat recovery step: Coolant from the DBD unit and cooling chamber is pumped into the heat exchanger and preheated by inert gas introduced into the pneumatic crushing and screening device and rotary kiln.

[0010] Preferably, the inert gas used in steps (2) and (4) is argon or an argon-hydrogen mixture.

[0011] The present invention also provides a continuous production system for high-purity lithium oxide, comprising a pneumatic crushing and screening device, a pretreatment rotary kiln, a material storage bin, a DBD plasma device, a cooling bin, a power supply system, a vacuum system, an inert gas conveying system, a temperature monitoring system, a pressure monitoring system, a cooling system, and an electromagnetic shielding system. in: The discharge port of the pneumatic crushing and screening device is connected to the inlet of the pretreatment rotary kiln; The discharge port of the pretreatment rotary kiln is connected to the inlet of the material storage bin; The material storage bin's discharge port is connected to the reaction chamber of the DBD plasma device via a material distribution mechanism; The outlet of the DBD plasma device is connected to the inlet of the cooling chamber via a negative pressure conveying pipe; The outlet of the cooling chamber is connected to the glove box; The vacuum system is connected to the exhaust ports of the pretreatment rotary kiln and the DBD plasma device, respectively. The inert gas conveying system is connected to the inlet of the pneumatic crushing and screening device, the pretreatment rotary kiln, and the DBD plasma device, respectively. The cooling system includes a heat exchanger, the heat exchanger’s heat medium inlet is connected to the upper electrode plate cooling channel of the DBD plasma device, the reaction chamber shell cooling channel and the cooling chamber interlayer, and its heat medium outlet is connected to the interlayer of the pretreatment rotary kiln. The output end of the inert gas conveying system is connected to the cold medium inlet of the heat exchanger, and the cold medium outlet of the heat exchanger is connected to the air inlet of the pneumatic crushing and screening device.

[0012] Preferably, the pneumatic crushing and screening device comprises: Three tangential air intakes are located on the bottom side of the compartment; A columnar filter screen is coaxially arranged inside the compartment, and the upper part of the columnar filter screen is connected to the discharge port at the top of the compartment; A conical flow guide device located at the bottom of the columnar filter screen; The rotating disc at the bottom of the compartment has multiple pairs of shredding blades arranged in a staggered pattern on its surface. An anti-stick coating covering the interior walls of the cabin; The purge air curtain is installed at the gap between the discharge port and the columnar filter screen.

[0013] Preferably, the pretreatment rotary kiln comprises: A stainless steel rotating cylinder with a jacket, the jacket being connected to the heat medium channel of the cooling system. An air inlet pipe and an air outlet pipe are respectively installed at the axis of both ends of the cylinder; The inner wall of the cylinder is equipped with a spiral baffle, the baffle height is 1-3cm and it forms an angle of 30°-60° with the axis; The cylinder body is tilted 5°-10° towards the discharge port.

[0014] Preferably, the DBD plasma device comprises: The upper and lower electrodes are parallel to each other in the reaction chamber, and the distance between the two electrodes is adjustable with a maximum distance ≤100mm. The upper electrode plate has 3-5 inclined grooves arranged radially on its surface. The lower electrode plate has 3-10 Archimedean spiral protrusions on its surface, with a protrusion height of 0-3cm and the height gradually becomes 0 within 15cm of the spiral tail. Coolant passage running through the upper electrode plate; A hot oil passage running through the lower electrode plate; An arc-shaped air inlet is located on the side wall of the reaction chamber, and an air outlet is located at the top. Water vapor sensor installed at the air outlet; The electric fabric feeding mechanism and the negative pressure suction mechanism are installed inside the cavity.

[0015] Preferably, the cooling chamber comprises: A sealed chamber with an inert gas atmosphere; A sandwich structure connecting the cooling system; The bottom outlet connects to a glove box, which maintains an inert atmosphere.

[0016] The technical effects and advantages of this invention are as follows: This invention effectively solves the process fluctuation problem caused by the hygroscopic agglomeration of lithium hydroxide by combining raw material pretreatment with inert gas protection. After crushing, screening, and low-temperature dehydration, the raw material directly enters the reaction stage in a closed conveying system, blocking the secondary moisture absorption path of the material. At the same time, through a uniquely designed electrode structure and a real-time gas monitoring system, the water vapor concentration in the reactor is significantly reduced, avoiding the risk of arc discharge. The lower electrode of the reactor adopts a raised structure with a specific geometric contour, which, in conjunction with rotational motion, optimizes the discharge uniformity and electric field distribution, greatly improving the breakdown voltage threshold. The airflow guiding feature set on the upper electrode accelerates the diffusion of by-products, further enhancing the stability and continuity of system operation.

[0017] This invention innovatively combines plasma activation with controllable heat conduction technology to achieve efficient decomposition of lithium hydroxide at low temperatures. This synergistic mechanism significantly reduces energy input requirements, shortens the reaction cycle, and completely avoids impurity formation caused by high-temperature side reactions. The entire process is carried out under an inert atmosphere, without the participation of chemical additives, and the decomposition product is only water vapor, which is recovered and reused through a recycling system. The waste heat integration system transfers the heat from the cooling medium to the raw material pretreatment stage, forming an energy closed loop. Overall energy consumption is significantly reduced compared to traditional processes, ultimately yielding high-purity single-phase lithium oxide.

[0018] This invention integrates automatic material feeding, online monitoring, and a closed conveying system, overcoming the bottleneck of intermittent production. Raw material crushing, dehydration, reaction, product collection, and packaging are seamlessly connected under inert gas protection, with intelligent control of the reaction endpoint via water vapor concentration feedback. A specialized reactor structure design ensures uniform heating and plasma irradiation of the material, while an electromagnetic shielding module eliminates interference between equipment. The entire system achieves continuous operation from raw material processing to high-purity lithium oxide packaging, effectively increasing production capacity and is applicable to industrial-grade lithium hydroxide raw materials with varying moisture contents. Detailed Implementation

[0019] This invention provides a continuous production process for high-purity lithium oxide based on DBD plasma technology. Using lithium hydroxide as raw material, and considering its hygroscopic nature, ensuring dryness during storage and handling is difficult, as it readily absorbs moisture and clumps. First, a pneumatic crushing and screening device controls the lithium hydroxide particle size to ≤500μm. Then, a specially designed rotary kiln pre-treats the lithium hydroxide, removing free water under slight negative pressure (vacuum degree -0.09~-0.07MPa) and temperature ≤105℃. This reduces the energy required for subsequent processing and minimizes the water vapor content between the plasma electrodes, lowering the probability of arc discharge. For anhydrous lithium hydroxide raw materials, the screening and crushing device can be omitted; the lithium hydroxide can be preheated directly in the rotary kiln. The dried / preheated lithium hydroxide is then fed into a material storage silo. The silo's discharge port is connected to the inlet of a specially designed plasma preparation device. The plasma device is first evacuated to 10℃. -2 Below Pa, an inert gas is introduced, maintaining the pressure inside the device at 0.1 Pa - 1 kPa. Lithium hydroxide powder is evenly applied to the groove of the lower electrode plate through a feeding port connected to the material storage chamber, with a feeding thickness of 1-30 mm. After feeding, the upper electrode plate is lowered to a distance of ≤35-100 mm from the lower electrode plate. The plasma equipment is connected to 200-700V, 10-80KHz, and a current density of 0.3-1A / cm². 2A high-frequency sinusoidal power supply generates glow discharge. The lower electrode rotates around its axis at 4π-14π radians / minute to increase the uniformity of plasma irradiation of the material. Cooling channels are distributed within both the upper electrode and the equipment casing. Hot oil channels are present in the lower electrode, which is heated to 200°C via a ball valve at the center of the electrode. The temperature of the lower electrode is monitored in real-time and linked to a cooling pump to control it from exceeding 450°C. The heated cooling liquid is then pumped to the rotary kiln. Under the combined effect of glow discharge irradiation and lower electrode heating, lithium hydroxide decomposes into lithium oxide with a purity ≥99.95% within 30-360 minutes. When the water vapor sensor detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and lithium oxide powder is extracted into the cooling chamber for storage through the negative pressure tube. The cooling chamber is inert gas atmosphere and the interlayer is connected to a coolant pump. The coolant from the upper electrode plate, the plasma equipment shell, and the cooling chamber is all pumped to the heat exchanger. The inert gas enters the pneumatic crushing and screening device through the heat exchanger. The waste heat is used to preheat lithium hydroxide to increase the dehydration pretreatment efficiency and further reduce the energy consumption of lithium oxide preparation. The cooling chamber is connected to a glove box, and the lithium oxide is encapsulated in the glove box protected by the inert atmosphere.

[0020] This invention also provides a continuous high-purity lithium oxide production system based on DBD plasma technology, mainly comprising a pneumatic crushing and screening device, a pretreatment rotary kiln, a material storage bin, a DBD plasma device, and a cooling bin, as well as auxiliary facilities such as a power supply system, a vacuum system, an inert gas conveying system, a temperature monitoring system, a pressure monitoring system, a cooling system, and an electromagnetic shielding system. Among these: The pneumatic crushing and screening device preferably has the following structure: Three evenly arranged tangential air inlets are provided on the bottom side of the device. These three tangential air inlets enhance the airflow within the chamber, forming a high-speed swirling airflow. The airflow swirls upwards from the bottom of the rotating disc along the perimeter of the chamber wall. After reaching the top of the crushing chamber, the airflow enters the inner cylinder along a guide plate. A columnar filter screen is located in the middle of the inner cylinder. The upper part of the filter screen connects to the discharge port at the top of the chamber. A conical device is provided at the lower part of the filter screen to guide the airflow upwards from the bottom of the screen. The bottom of the inner cylinder connects to the rotating disc. The feed inlet is located on the side of the chamber wall, higher than the rotating disc. After the raw material enters the chamber, it is separated by the swirling airflow. Lighter materials are carried upwards by the airflow into the inner cylinder and reach the filter screen. Heavier materials fall onto a rotating disc, on which crushing blades are arranged in a staggered pattern. The rotation direction is opposite to the airflow, increasing the relative speed of the material impacting the blades. The material collides with the high-speed rotating blades under the influence of the high-speed rotating airflow. The crushing chamber controls the particle size of the material by controlling the mesh size of the filter screen and the crushing efficiency by controlling the rotation speed of the rotating disc. The material after being screened by the mesh size is carried by the airflow through the discharge port into the pretreatment rotary kiln. The entire inner wall of the crushing chamber is covered with an anti-scratch and anti-stick coating. A purge air curtain is installed at the gap between the discharge port at the top of the chamber and the inner cylinder. The purge air curtain is manually opened according to the airflow difference between the air inlet and outlet of the crushing chamber to clean and prevent clogging of the intermediate filter screen. The pretreatment rotary kiln preferably has the following structure: it includes a support frame, a motor, a transmission device, and a rotating cylinder. The cylinder is made of stainless steel with a jacket, the jacket being connected to hot water. Both ends of the cylinder are closed, and an inlet pipe and an outlet pipe are respectively connected at the shaft center. One end connected to the inlet pipe has a discharge port, and the other end connected to the outlet pipe has a feed port. A sensor is installed on the outlet pipe to monitor the water vapor content. The inert gas is heated by the heat exchanger of the cooling system and then enters the cylinder through the inlet pipe at the shaft center. The hot water in the jacket and the heated inert gas together pretreat the lithium hydroxide inside the cylinder. The outlet pipe at the shaft center of one end of the cylinder is connected to an air pump to extract the inert gas containing water vapor. The inert gas is then dehydrated and dried. After drying, the material re-enters the rotary kiln. The entire cylinder is tilted 5-10° towards the discharge port. The inner wall of the cylinder has 2-5 sets of baffles with protrusions of 5-10 cm and rotating at 15-40°. The baffles fully turn the material. A temperature sensor is installed near the discharge port to detect the material temperature. The temperature and flow rate of inert gas and hot water are controlled in conjunction to ensure that the material temperature does not exceed 110℃. When the sensor at the outlet pipe does not detect water vapor, the material is sent from the discharge port to the material storage bin in conjunction with the rotation of the cylinder. The material storage bin is covered with insulation material. During the pretreatment process, the flow rate of the inlet pipe is slightly greater than that of the outlet pipe. Inert gas is continuously blown during the lithium hydroxide pretreatment and the discharge process after drying. The DBD plasma device preferably has the following structure: Two parallel metal discs are disposed inside the cavity, with a gap of 5-15 cm between the cavity and the side of the metal plates. A screw and a precision servo motor are connected to the upper metal plate to adjust the gap between the upper and lower plates. A servo motor is connected to the lower metal plate to drive its rotation. The upper and lower metal plates are connected to a medium-frequency power supply. The upper plate has 3-5 evenly distributed grooves along the radial direction, with the grooves tilting upwards from the center along the Z-axis to guide rapid gas diffusion. The lower plate... The surface is covered with 3-10 spiral protrusions arranged in an Archimedean spiral pattern, with a protrusion height of 0-3cm. The height of the protrusions smoothly decreases from the last 10-15cm of the spiral to zero at the end. The upper electrode plate has coolant channels, and the lower electrode plate has hot oil channels. Hot oil is connected to the lower electrode plate via a ball valve at the center of the electrode plate to heat it. Two opposing arc-shaped air inlets, each one-third the length of the lower electrode plate, are located 1-5cm below the lower electrode plate along the Z-axis direction. An air outlet is located in the center of the top of the cavity. A water vapor sensor is installed and connected to an air pump to extract inert gas containing water vapor. The air pump adjusts its frequency in real time according to the detected water vapor content to ensure timely extraction of the inert gas containing water vapor. The extraction air pump and the intake air pump work together to maintain the air pressure inside the chamber. The inert gas is dehydrated and dried before re-entering the chamber. Two electric supports are symmetrically installed at the height of the upper and lower electrode plates. One support is equipped with a feeding port and a scraper. The feeding port is flat and its width matches the groove between the protrusions of the lower electrode plate. The scraper is located on one side of the feeding port, which is connected to the feed pipe. The material feeding valve connects to the material storage bin. During material feeding, the upper electrode plate rises, and the support controls the feeding port to move from the outside to the inside along the raised line of the lower electrode plate. Simultaneously, the lower electrode plate rotates. The feeding speed, the rotation speed of the lower electrode plate, and the height of the scraper are adjusted to control the material thickness. The scraper adjusts the material height while ensuring the flatness of the material. Another support has a suction port connected to a negative suction pipe. After material processing is completed, the upper electrode plate rises, and the program-controlled electric arm transports the high-purity lithium oxide from the lower electrode plate to the cooling chamber through the negative suction pipe. An infrared sensor is installed on the chamber to monitor the temperature of the lower electrode plate. This sensor works in conjunction with the lower electrode plate heating oil pump and hot oil heater to prevent the local temperature of the lower electrode plate from exceeding 450°C, thus avoiding the melting of lithium hydroxide.

[0021] Based on the above system, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0022] Example 1 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disc rotate against the airflow at a set speed. The particle size is controlled to 500 μm through a 35-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 110 minutes under a slightly negative pressure (vacuum degree -0.08 MPa) and an inert atmosphere at 108°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 30 mm, in conjunction with the rotation of the lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 800 Pa. After the material distribution is completed, the upper electrode plate... The plasma is lowered to 85 mm from the lower electrode plate. The plasma equipment is connected to a 700V, 80KHz, 1A / cm² high-frequency sinusoidal power supply to generate glow discharge. The lower electrode plate rotates around its axis at 4π radians / minute. The lower electrode plate channel is connected to hot oil through a central ball valve. The temperature of the lower electrode plate is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is treated under the combined effect of glow discharge irradiation and lower electrode plate heating. When the water vapor sensor on the equipment casing detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through a negative pressure pipe. After 345 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.95% and a water content of 98ppm is obtained.

[0023] Example 2 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disc rotate against the airflow at a set speed. The particle size is controlled to 350 μm through a 45-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 95 minutes under a slightly negative pressure (vacuum degree -0.07 MPa) and an inert atmosphere at 108°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 10 mm, under the rotation of the lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 650 Pa. After the material distribution is completed, the upper electrode plate... The plasma is lowered to a distance of 45 mm from the lower electrode plate. The plasma equipment is connected to a high-frequency sinusoidal power supply of 380V, 40KHz, with a current density of 0.6A / cm² to generate glow discharge. The lower electrode plate rotates around its axis at 6π radians / minute. The lower electrode plate channel is connected to hot oil through a central ball valve. The temperature of the lower electrode plate is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is treated under the combined effect of glow discharge irradiation and heating of the lower electrode plate. When the water vapor sensor on the equipment shell detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through a negative pressure pipe. After 265 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.97% and a water content of 68ppm is obtained.

[0024] Example 3 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disc rotate against the airflow at a set speed. The particle size is controlled to 250 μm through a 60-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 70 minutes under a slightly negative pressure (vacuum degree -0.09 MPa) and an inert atmosphere at 105°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 20 mm, under the rotation of the lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 350 Pa. After the material distribution is completed, the upper electrode plate... The plasma is lowered to a distance of 55 mm from the lower electrode plate. The plasma equipment is connected to a high-frequency sinusoidal power supply of 480V, 60KHz, and a current density of 0.6A / cm² to generate glow discharge. The lower electrode plate rotates around its axis at 8π radians / minute. The lower electrode plate channel is connected to hot oil through a central ball valve. The temperature of the lower electrode plate is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is treated under the combined effect of glow discharge irradiation and heating of the lower electrode plate. When the water vapor sensor on the equipment shell detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through a negative pressure pipe. After 220 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.98% and a water content of 85ppm is obtained.

[0025] Example 4 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disc rotate against the airflow at a set speed. The particle size is controlled to 104 μm through a 140-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 55 minutes under a slightly negative pressure (vacuum degree -0.085 MPa) and an inert atmosphere at 105°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with the lower electrode plate rotating in coordination. The material thickness is 25 mm. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 220 Pa. After the material distribution is completed, the upper electrode plate... The plasma is lowered to a distance of 75 mm from the lower electrode plate. The plasma equipment is connected to a high-frequency sinusoidal power supply of 650V, 80KHz, and a current density of 0.8A / cm² to generate glow discharge. The lower electrode plate rotates around its axis at 6π radians / minute. The lower electrode plate channel is connected to hot oil through a central ball valve. The temperature of the lower electrode plate is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is treated under the combined effect of glow discharge irradiation and heating of the lower electrode plate. When the water vapor sensor on the equipment shell detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through the negative pressure pipe. After 178 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.96% and a water content of 92ppm is obtained.

[0026] Example 5 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disk rotate against the airflow at a set speed. The particle size is controlled to 30μm through a 460-mesh screen. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 30 minutes under a slightly negative pressure (vacuum degree -0.075MPa) and an inert atmosphere at 100℃. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 5 mm, under the rotation of the lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 50Pa. After the material distribution is completed, the upper electrode plate... The plasma is lowered to a distance of 35 mm from the lower electrode plate. The plasma equipment is connected to a 220V, 15KHz, 0.3A / cm² high-frequency sinusoidal power supply to generate glow discharge. The lower electrode plate rotates around its axis at 2π radians / minute. The lower electrode plate channel is connected to hot oil through a central ball valve. The temperature of the lower electrode plate is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is treated under the combined effect of glow discharge irradiation and lower electrode plate heating. When the water vapor sensor on the equipment casing detects that the water vapor content in the exhaust gas is 0, the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through a negative pressure pipe. After 30 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.98% and a water content of 60ppm is obtained.

[0027] Comparative Example 1 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disk rotate against the airflow at a set speed. The particle size is controlled to 250 μm through a 60-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 70 minutes under a slightly negative pressure (vacuum degree -0.09 MPa) and an inert atmosphere at 105°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 20 mm, under the cooperation of the rotating lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 350 Pa. After the material distribution is completed... The upper electrode plate descends to a distance of 55 mm from the lower electrode plate; the plasma equipment is connected to a 480V, 60KHz, 0.6A / cm² high-frequency sinusoidal power supply to generate glow discharge, and the lower electrode plate rotates around its axis at 8π radians / minute; the lower electrode plate channel is not connected to hot oil; the lower electrode plate temperature is monitored in real time and linked to the hot oil pump to control the material contact temperature; lithium hydroxide is treated under glow discharge irradiation, and when the water vapor sensor on the equipment casing detects that the water vapor content in the exhaust gas is 0 (after 600 minutes), the plasma power supply is turned off, the upper electrode plate rises, and the lithium oxide powder is extracted to the cooling chamber for storage through the negative pressure pipe; after 600 minutes of plasma irradiation treatment, lithium oxide with a purity of 99.96% and a water content of 63ppm is obtained.

[0028] Comparative Example 2 Untreated lumpy lithium hydroxide raw material (without crushing, screening, or rotary kiln pretreatment) is directly fed into the material storage bin; the lumpy lithium hydroxide is fed into the material storage bin; the feeding valve is opened, and the material is fed into the groove through the feeding port and scraper, with the lower electrode plate rotating to complete the material feeding, with a feeding thickness of 25 mm; the DBD plasma device is evacuated to the set value and then argon gas is introduced to maintain the internal pressure at 220 Pa; after the material feeding is completed, the upper electrode plate descends to 75 mm from the lower electrode plate; the plasma device is connected to a 650V, 80KHz, 0.8A / cm² high-frequency sine wave power supply to generate glow discharge, and the lower electrode plate emits a 6π... The lower electrode rotates around its axis in arcs / minutes; the lower electrode channel is connected to hot oil through a central ball valve, and the temperature of the lower electrode is monitored in real time and linked to the hot oil pump to control the material contact temperature; multiple arc breakdowns occur during the process; lithium hydroxide is treated under the combined effect of glow discharge irradiation and lower electrode heating. When the water vapor sensor on the equipment shell detects that the water vapor content in the exhaust gas is 0 (after 288 minutes), the plasma power supply is turned off, the upper electrode rises, and the lithium oxide powder is extracted to the cooling chamber for storage through the negative pressure pipe; after 288 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.26% and a water content of 180 ppm is obtained.

[0029] Comparative Example 3 Moisture-absorbing and agglomerated lithium hydroxide raw material is fed into a pneumatic crushing and screening device. A high-speed swirling airflow is formed through three tangential air inlets. Crushing blades on a rotating disk rotate against the airflow at a set speed. The particle size is controlled to 350 μm through a 45-mesh sieve. After crushing, the material is loaded into a pretreatment rotary kiln with argon gas and treated for 95 minutes under a slightly negative pressure (vacuum degree -0.07 MPa) and an inert atmosphere at 108°C. The dehydrated lithium hydroxide is then sent to a material storage bin. The feeding valve is opened, and the material is evenly distributed through the feeding port and scraper plate, with a thickness of 10 mm, under the rotation of the lower electrode plate. After evacuating the DBD plasma device to the set value, argon gas is introduced to maintain the internal pressure at 650 Pa. After the material distribution is completed, the upper electrode plate descends to 30 mm from the lower electrode plate. The plasma equipment is connected to a 380V, 40KHz high-frequency sinusoidal power supply with a current density of 0.6A / cm² to generate glow discharge. The lower electrode rotates around its axis at 6π radians / minute. The lower electrode is replaced with a smooth metal plate without protrusions. The channels of the lower electrode are connected to hot oil through a ball valve. The temperature of the lower electrode is monitored in real time and linked to the hot oil pump to control the material contact temperature. Lithium hydroxide is processed under the combined effect of glow discharge irradiation and heating of the lower electrode. When the water vapor sensor on the equipment shell detects that the water vapor content in the exhaust gas is 0 (after 425 minutes), the plasma power supply is turned off, the upper electrode rises, and the lithium oxide powder is extracted to the cooling chamber for storage through a negative pressure pipe. After 425 minutes of combined plasma and thermal decomposition treatment, lithium oxide with a purity of 99.52% and a water content of 108ppm is obtained.

[0030] For specific comparison parameter settings, please refer to Table 1 below: Table 1 Comparison of parameter settings between the examples and comparative examples Raw material particle size / μm Rotary kiln temperature / ℃ Preprocessing time / minute Fabric thickness / mm Internal air pressure of DBD device Plate spacing / mm Plasma power supply Lower electrode speed Time / minutes Lithium oxide purity Lithium oxide water content / ppm Example 1 500(35) mesh) 108 110 30 800 85 <![CDATA[700V,80KHZ,1A / cm 2 ]]> 4ᴨ 345 99.95 98 Example 2 350（45） 108 95 10 650 45 <![CDATA[380V,40KHZ,0.6A / cm 2 ]]> 6ᴨ 265 99.97 68 Example 3 250（60） 105 70 20 350 55 <![CDATA[480V,60KHZ0.6A / cm 2 ]]> 8ᴨ 220 99.98 85 Example 4 104（140） 105 55 25 220 75 <![CDATA[650V,80KHZ,0.8A / cm 2 ]]> 6ᴨ 178 99.96 92 Example 5 30（460） 100 30 5 50 35 <![CDATA[220V,15KHZ,0.3A / cm 2 ]]> 2ᴨ 30 99.98 60 Comparative Example 1 250（60） 105 70 20 350 55 <![CDATA[480V,60KHZ0.6A / cm 2 ]]> 8ᴨ 600 99.96 63 Comparative Example 2 / / / 25 220 75 <![CDATA[650V,80KHZ,0.8A / cm 2 ]]> 6ᴨ 288 99.26 180 Comparative Example 3 350（45） 108 95 10 650 30 <![CDATA[380V,40KHZ,0.6A / cm 2 ]]> 6ᴨ 425 99.52 108 The chemical composition of the products prepared in the examples and comparative examples was analyzed, and the results are shown in Table 2 below: Table 2

[0031] The lithium oxide prepared in Examples 1-5 was subjected to X-ray diffraction analysis, and it was consistent with the lithium oxide standard card (ICDDPDF#12-0254), indicating that it was cubic lithium oxide with no lithium carbonate or lithium hydroxide impurity peaks.

[0032] Microstructure: The lithium oxide prepared in Examples 1-5 was characterized by scanning electron microscopy and showed monodisperse μm particles with narrow particle size distribution (X±0.5um), clear particle edges, and no obvious impurities or foreign matter.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A continuous production process for high-purity lithium oxide based on DBD plasma technology, characterized in that, Includes the following steps: (1) Input lithium hydroxide raw material into a pneumatic crushing and screening device and crush and screen it to a particle size ≤500μm; (2) Input the material obtained in step (1) into the pretreatment rotary kiln, remove free water under a slight negative pressure condition of vacuum degree -0.09~-0.07MPa and an inert atmosphere of temperature ≤105℃ to obtain dehydrated lithium hydroxide; (3) Dehydrated lithium hydroxide is transported to the DBD plasma device through a material storage bin and uniformly covered on the surface of the lower electrode plate by a material covering mechanism, with a material thickness of 1~30mm; (4) After evacuating the DBD plasma device to below 10⁻²Pa, introduce inert gas to maintain the pressure inside the cavity at 0.1Pa~1kPa; (5) Adjust the upper electrode of the DBD plasma device to descend to 35~100mm from the lower electrode, and apply a high-frequency sinusoidal power supply of 200~700V, 10~80kHz, and current density of 0.3~1A / cm² to generate glow. (6) Start the lower electrode plate to rotate at 4π~14π radians / minute, and at the same time, heat is supplied through the hot oil channel inside the lower electrode plate to maintain the material contact surface temperature at 200~450℃; (7) The reaction was stopped when the content of the exhaust gas was 0 by synergistic plasma irradiation and thermal decomposition for 30 to 360 minutes and monitored by a water vapor sensor. (8) Lithium oxide powder is extracted under negative pressure and cooled and packaged in an inert atmosphere cooling chamber.

2. The continuous production process for high-purity lithium oxide according to claim 1, characterized in that, In step (1), the pneumatic crushing and screening process forms a high-speed vortex through tangential air intake, the crushing blades rotate in the opposite direction to the airflow vortex, and the filter screen controls the particle size to ≤500μm.

3. The continuous production process for high-purity lithium oxide according to claim 1, characterized in that, In step (3), the fabric thickness is 5-25mm.

4. The continuous production process for high-purity lithium oxide according to claim 1, characterized in that, It also includes waste heat recovery steps: Coolant from the DBD unit and cooling chamber is pumped into the heat exchanger and preheated by inert gas introduced into the pneumatic crushing and screening device and rotary kiln.

5. The continuous production process for high-purity lithium oxide according to claim 1, characterized in that: The inert gas used in steps (2) and (4) is argon or an argon-hydrogen mixture.

6. A continuous production system for high-purity lithium oxide, characterized in that, It includes a pneumatic crushing and screening device, a pretreatment rotary kiln, a material storage bin, a DBD plasma device, a cooling bin, a power supply system, a vacuum system, an inert gas conveying system, a temperature monitoring system, a pressure monitoring system, a cooling system, and an electromagnetic shielding system; in: The discharge port of the pneumatic crushing and screening device is connected to the inlet of the pretreatment rotary kiln; The discharge port of the pretreatment rotary kiln is connected to the inlet of the material storage bin; The material storage bin's discharge port is connected to the reaction chamber of the DBD plasma device via a material distribution mechanism; The outlet of the DBD plasma device is connected to the inlet of the cooling chamber via a negative pressure conveying pipe; The outlet of the cooling chamber is connected to the glove box; The vacuum system is connected to the exhaust ports of the pretreatment rotary kiln and the DBD plasma device, respectively. The inert gas conveying system is connected to the inlet of the pneumatic crushing and screening device, the pretreatment rotary kiln, and the DBD plasma device, respectively. The cooling system includes a heat exchanger, the heat exchanger’s heat medium inlet is connected to the upper electrode plate cooling channel of the DBD plasma device, the reaction chamber shell cooling channel and the cooling chamber interlayer, and its heat medium outlet is connected to the interlayer of the pretreatment rotary kiln. The output end of the inert gas conveying system is connected to the cold medium inlet of the heat exchanger, and the cold medium outlet of the heat exchanger is connected to the air inlet of the pneumatic crushing and screening device.

7. The high-purity lithium oxide continuous production system according to claim 6, characterized in that, The pneumatic crushing and screening device includes: Three tangential air intakes are located on the bottom side of the compartment; A columnar filter screen is coaxially arranged inside the compartment, and the upper part of the columnar filter screen is connected to the discharge port at the top of the compartment; A conical flow guide device located at the bottom of the columnar filter screen; The rotating disc at the bottom of the compartment has multiple pairs of shredding blades arranged in a staggered pattern on its surface. An anti-stick coating covering the interior walls of the cabin; The purge air curtain is installed at the gap between the discharge port and the columnar filter screen.

8. The high-purity lithium oxide continuous production system according to claim 6, characterized in that, The pretreatment rotary kiln includes: A stainless steel rotating cylinder with a jacket, the jacket being connected to the heat medium channel of the cooling system. An air inlet pipe and an air outlet pipe are respectively installed at the axis of both ends of the cylinder; The inner wall of the cylinder is equipped with a spiral baffle, the baffle height is 1-3cm and it forms an angle of 30°-60° with the axis; The cylinder body is tilted 5°-10° towards the discharge port.

9. The high-purity lithium oxide continuous production system according to claim 6, characterized in that, The DBD plasma device includes: The upper and lower electrodes are parallel to each other in the reaction chamber, and the distance between the two electrodes is adjustable with a maximum distance ≤100mm. The upper electrode plate has 3-5 inclined grooves arranged radially on its surface. The lower electrode plate has 3-10 Archimedean spiral protrusions on its surface, with a protrusion height of 0-3cm and the height gradually becomes 0 within 15cm of the spiral tail. Coolant passage running through the upper electrode plate; A hot oil passage running through the lower electrode plate; An arc-shaped air inlet is located on the side wall of the reaction chamber, and an air outlet is located at the top. Water vapor sensor installed at the air outlet; The electric fabric feeding mechanism and the negative pressure suction mechanism are installed inside the cavity.

10. The high-purity lithium oxide continuous production system according to claim 6, characterized in that, The cooling chamber includes: A sealed chamber with an inert gas atmosphere; A sandwich structure connecting the cooling system; The bottom outlet connects to a glove box, which maintains an inert atmosphere.

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