A mobile anode electrochemical pre-lithiation device and lithium replenishment control method

Abstract

The present invention proposes a mobile anode electrochemical pre-lithiation device and a method for controlling the amount of lithium replenishment, which belongs to the technical field of lithium-ion batteries. The pre-lithiation device of the present invention includes a pole piece conveying device, an unwinding device, a first guide assembly, a plating solution tank, a second guide assembly and a winding device connected in sequence. The unwinding device includes an unwinding seat, an unwinding main board, a first unwinding mechanism and a second unwinding mechanism installed on the unwinding main board. The unwinding main board is arranged on the unwinding seat. The first unwinding mechanism is used to convey the A-side anode strip, and the second unwinding mechanism is used to convey the B-side anode strip. The pole piece conveying device delivers the negative pole piece to be replenished with lithium to the incoming material receiving roller arranged on the unwinding main board to form a pole piece conveying line. The pole piece conveying line is located between the first unwinding mechanism and the second unwinding mechanism. The design of the mobile anode of the present invention ensures the continuous renewal of the lithium source, avoids the problem of local lithium depletion that may be caused by the fixed anode, and ensures the uniformity of the lithium replenishment process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a mobile anode electrochemical pre-lithiation device and a lithium replenishment amount control method. Background Art

[0002] The biggest shortcoming of the traditional lithium powder lithium replenishment and pre-lithiation process is its lack of uniformity. Lithium powder has problems with physical agglomeration and electrostatic agglomeration during the sprinkling process. In addition, due to the light specific gravity of lithium powder, lithium powder floats during the sprinkling process. At the same time, the adhesion of the rolling roller to the lithium powder is also a serious problem, which wastes lithium powder and causes worse uniformity. Although the accuracy and operability of lithium strip calendering lithium replenishment and pre-lithiation are much better than lithium powder replenishment, it is limited by the accuracy of the calendering roller. This amount of lithium replenishment is excessive for the negative electrode material of many systems. In order to reduce the side effects of excessive lithium replenishment on the battery, other process methods must be used to make up for the defects or make breakthroughs in the materials. In addition, inert lithium powder spraying pre-lithiation, the inert lithium powder is made into a slurry and sprayed onto the surface of the negative electrode sheet, and then the lithium carbonate shell of the inert lithium powder is fractured by external force before winding or laminating. While this process can replenish lithium in negative electrode sheets under normal conditions, it can be incomplete when fracturing the lithium carbonate shell. Due to the limited hardness of the active material coating the electrode, some of the inert lithium powder will become embedded in the active material when external force is applied to fracture the shell, preventing it from being fractured. The remaining inert lithium powder, encased in the lithium carbonate shell, cannot fully replenish the lithium. This affects both the consistency and total amount of lithium replenishment.

[0003] In order to achieve precise control of the degree of lithiation, it is currently mainly achieved by monitoring and controlling some key parameters in the lithium replenishment process. During the electrochemical lithium replenishment process, the amount of lithium ion insertion can be regulated by precisely setting and controlling the lithium replenishment current and time, thereby achieving the purpose of controlling the degree of lithiation. However, these methods have certain limitations. Due to the complex actual conditions of batteries, factors such as the microstructure of the electrode material, the composition and distribution of the electrolyte, etc. will affect the degree of lithiation, making precise control of the degree of lithiation still an extremely challenging task. There is an urgent need to design a lithium replenishment device and method to meet actual production needs. Summary of the Invention

[0004] The object of the present invention is to provide a mobile anode electrochemical pre-lithiation device and a lithium replenishment amount control method to solve the problems of the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention discloses a mobile anode electrochemical pre-lithiation device, comprising a pole piece conveying device, an unwinding device, a first guide assembly, a plating bath, a second guide assembly and a winding device connected in sequence.

[0007] The unwinding device includes an unwinding seat, an unwinding main board, a first unwinding mechanism and a second unwinding mechanism installed on the unwinding main board. The unwinding main board is arranged on the unwinding seat. The first unwinding mechanism is used to convey the A-side anode strip, and the second unwinding mechanism is used to convey the B-side anode strip. The electrode sheet conveying device conveys the negative electrode sheet to be replenished with lithium to the incoming material receiving roller arranged on the unwinding main board to form an electrode sheet conveying line. The electrode sheet conveying line is located between the first unwinding mechanism and the second unwinding mechanism.

[0008] The first guide assembly includes a guide roller, a pole piece conductive roller, a first conductive roller, a second conductive roller and a bonding roller. The negative electrode sheet to be replenished passes through the guide roller and the pole piece conductive roller in sequence after the incoming material receiving roller. The A-side anode strip passes through the guide roller and the first conductive roller in sequence after the first unwinding mechanism. The B-side anode strip passes through the guide roller and the second conductive roller in sequence after the second unwinding mechanism. The negative electrode sheet to be replenished, the A-side anode strip and the B-side anode strip are gathered together and then enter the plating bath through the bonding roller.

[0009] The negative electrode sheet to be replenished with lithium undergoes an electrochemical reaction in the plating bath to obtain a pre-lithiated electrode sheet. The pre-lithiated electrode sheet, the A-side anode strip, and the B-side anode strip are wound up by a winding device through a second guide assembly.

[0010] As a preferred implementation scheme of this embodiment, the winding device includes a winding seat, a winding main board, an electrode winding mechanism, a first winding mechanism and a second winding mechanism. The winding main board stands on the winding seat. The first winding mechanism is used for winding the A-side anode strip, and the second unwinding mechanism is used for winding the B-side anode strip. The electrode winding mechanism is arranged between the first winding mechanism and the second winding mechanism, and both are installed on the winding main board; the second guide assembly includes a bonding roller and a guide roller. After the pre-lithiation electrode, the A-side anode strip and the B-side anode strip come out of the plating tank together, they pass through the bonding roller and are then connected to their corresponding winding mechanisms by their respective guide rollers.

[0011] Further preferably, the A-side anode belt and the B-side anode belt both have metallic lithium attached to one side of the conductive belt, and a layer of isolation film is introduced into the side of the A-side anode belt or the B-side anode belt with metallic lithium, and the side of the A-side anode belt or the B-side anode belt with the isolation film is bonded to the front side of the negative electrode sheet to be replenished with lithium.

[0012] Further preferably, a layer of isolation film is introduced into the negative electrode sheet to be replenished before entering the incoming material receiving roller, and is arranged on the reverse side of the negative electrode sheet to be replenished. The B-side anode strip / A-side anode strip has a side with metallic lithium and is bonded to the isolation film arranged on the reverse side of the negative electrode sheet to be replenished.

[0013] Further preferably, the negative electrode sheet to be replenished with lithium forms a stacked structure in the plating bath, and the stacked structure is composed of a conductive tape, metallic lithium, an isolation film, a pre-lithiated electrode sheet, an isolation film, metallic lithium, and a conductive tape in sequence.

[0014] As a preferred implementation manner of this embodiment, a controller is further included, and the electrode conveying device, unwinding device, plating solution pool and winding device are all electrically connected to the controller.

[0015] Another aspect of the present invention discloses a lithium replenishment control method for a mobile anode electrochemical pre-lithiation device, the lithium replenishment control method comprising the following steps:

[0016] S1, the amount of lithium replenishment is adjusted by the electroplating current I and the tape speed v. Since the current efficiency needs to be considered in the actual control process , the porosity of the negative electrode As well as the effect of the plating bath temperature T on the amount of lithium replenishment, based on Faraday's law, an enhanced lithium replenishment equation is established:

[0017]

[0018]

[0019] in, is the estimated lithium replenishment amount, in mg / cm²; I is the electroplating current, in A; L is the length of the plating bath, in m; is the molar mass of lithium, in g / mol; Represents the number of electrons transferred in the lithium ion intercalation reaction; is the Faraday constant, in C / mol; v is the tape speed, in m / min; is the current efficiency, dimensionless;

[0020] is the effective area coefficient, dimensionless; is the effective reaction area, in cm²; is the nominal geometric area of ​​the negative electrode sheet, in cm²; is the porosity, dimensionless; is the shape factor of the negative electrode material, dimensionless;

[0021] S2. In order to accurately replenish lithium and ensure equipment safety, an objective function is introduced. The objective function needs to include the optimization of the deviation of the system state quantity and the control quantity, and dynamic compensation is performed using the model predictive control algorithm. The objective function J satisfies the relationship: J

[0022] in, To predict the amount of lithium supplementation; The target amount of lithium supplementation; is the voltage change rate; is the safety-accuracy trade-off coefficient;

[0023] Set the constraints of the objective function: , , , , solve the objective function and output the optimal (I,v) combination;

[0024] in, and are the minimum and maximum allowable values ​​of electroplating current respectively; is the voltage, is the voltage safety threshold; The minimum and maximum allowable values ​​of the tape speed respectively; is the minimum value of current efficiency;

[0025] S3, the controller sends the optimal (I, v) combination of new parameters to the actuator. After the actuator executes the instruction, it monitors the device status in real time.

[0026] S4, the sensor collects data in real time, and the random forest classifier extracts features based on the collected real-time data. The features are voltage , voltage change rate , current efficiency , the concentration gradient of lithium ions Δ[Li + ] and anode impedance Ra, match the corresponding fault mode through feature combination, and determine whether the match triggers protection action or returns to normal signal.

[0027] In a further preferred embodiment, the process of matching the corresponding fault mode by the feature combination in step S4 and determining whether the match triggers the protection action or returns the normal signal is as follows:

[0028] The first fault mode is lithium dendrite growth, and the characteristic combination corresponding to the first fault mode is the voltage change rate. The concentration gradient of lithium ions increases and the concentration gradient of lithium ions increases. + ]decline;

[0029] The second fault mode is anode passivation, and the characteristic combination corresponding to the second fault mode is an increase in anode impedance Ra and a decrease in current efficiency η;

[0030] The third fault mode is the blocking of the isolation membrane, and the characteristic combination corresponding to the third fault mode is the voltage U rising and the current I falling;

[0031] When none of the above three fault modes are matched, it is determined that there is no fault and a normal signal is returned.

[0032] In summary, the beneficial effects of the present invention are:

[0033] The present invention can achieve precise control of the amount of lithium ion insertion by precisely controlling the electroplating current and the tape speed, thereby improving the accuracy of lithium replenishment. At the same time, the design of the mobile anode ensures the continuous renewal of the lithium source, avoids the problem of local lithium depletion that may be caused by a fixed anode, and ensures the uniformity of the lithium replenishment process.

[0034] By forming a layered structure in the plating bath, including a conductive strip, metallic lithium, a separator, and a pre-lithiated electrode, the present invention not only improves the battery's pre-lithiation efficiency but also forms a solid electrolyte interface film on the surface of the negative electrode, enhancing the battery's electrochemical stability and safety. Furthermore, the separator effectively blocks direct contact between the positive and negative electrodes, preventing the risk of short circuits.

[0035] The reusability of the mobile anode reduces material costs, while the application of an enhanced lithium replenishment equation and model predictive control algorithm makes the lithium replenishment process more automated and intelligent, reducing manual intervention and operating costs. Furthermore, through real-time monitoring and fault diagnosis, problems in the production process can be promptly identified and addressed, further improving the stability and reliability of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the mobile anode electrochemical pre-lithiation device of the present invention;

[0037] Figure 2 It is a schematic diagram of the stacked structure in the plating bath of the mobile anode electrochemical pre-lithiation device of the present invention;

[0038] Figure 3 yes Figure 2 A magnified view of point A;

[0039] Among them: 100-negative electrode sheet to be replenished with lithium, 101-material receiving roller, 200-unwinding device, 201-unwinding main board, 202-unwinding seat, 300-plating solution tank, 400-winding device, 401-winding main board, 402-winding seat, 403-electrode sheet winding mechanism, 1-A side anode belt, 2-pre-lithiation electrode sheet, 3-B side anode belt, 4-first unwinding mechanism, 41-first winding mechanism, 5-second unwinding mechanism, 51-second winding mechanism, 6-guide roller, 7-electrode sheet conductive roller, 8-first conductive roller, 81-second conductive roller, 9-laminating roller, 10-isolating film, 20-metal lithium, 30-conductive belt. DETAILED DESCRIPTION

[0040] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention and cannot be used to limit the present invention.

[0041] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also have other implementations and variations thereof. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0042] like Figures 1 to 3 As shown, this embodiment discloses a mobile anode electrochemical pre-lithiation device, including a pole piece conveying device, an unwinding device 200, a first guide assembly, a plating bath 300, a second guide assembly and a winding device 400 connected in sequence.

[0043] The unwinding device 200 includes an unwinding seat 202, an unwinding main board 201, a first unwinding mechanism 4 and a second unwinding mechanism 5 installed on the unwinding main board 201. The unwinding main board 201 is provided on the unwinding seat 202. The first unwinding mechanism 4 is used to convey the A-side anode strip 1, and the second unwinding mechanism 5 is used to convey the B-side anode strip 3. The electrode sheet conveying device conveys the negative electrode sheet 100 to be replenished with lithium to the incoming material receiving roller 101 provided on the unwinding main board 201, forming an electrode sheet conveying line. The electrode sheet conveying line is located between the first unwinding mechanism 4 and the second unwinding mechanism 5.

[0044] The first guide assembly includes a guide roller 6, a pole piece conductive roller 7, a first conductive roller 8, a second conductive roller 81 and a bonding roller 9. The negative electrode sheet 100 to be replenished with lithium passes through the guide roller 6 and the pole piece conductive roller 7 in sequence after passing through the incoming material receiving roller 101. The A-side anode strip 1 passes through the guide roller 6 and the first conductive roller 8 in sequence after passing through the first unwinding mechanism 4. The B-side anode strip 3 passes through the guide roller 6 and the second conductive roller 81 in sequence after passing through the second unwinding mechanism 5. The negative electrode sheet 100 to be replenished with lithium, the A-side anode strip 1 and the B-side anode strip 3 are gathered together and then pass through the bonding roller 9 into the plating bath 300;

[0045] The negative electrode sheet 100 to be replenished with lithium undergoes an electrochemical reaction in the plating bath 300 to obtain a pre-lithiated electrode sheet 2 . The pre-lithiated electrode sheet 2 , the A-side anode strip 1 , and the B-side anode strip 3 are wound up by the winding device 400 through the second guide assembly.

[0046] As a preferred implementation scheme of this embodiment, the winding device 400 includes a winding seat 402, a winding main board 401, a pole piece winding mechanism 403, a first winding mechanism 41 and a second winding mechanism 51. The winding main board 401 stands on the winding seat 402. The first winding mechanism 41 is used for winding the A-side anode strip 1, and the second unwinding mechanism 5 is used for winding the B-side anode strip 3. The pole piece winding mechanism 403 is arranged between the first winding mechanism 41 and the second winding mechanism 51, and both are installed on the winding main board 401; the second guide assembly includes a bonding roller 9 and a guide roller 6. After the pre-lithiation pole piece 2, the A-side anode strip 1 and the B-side anode strip 3 come out of the plating solution pool 300 together, they pass through the bonding roller 9 and are then connected to their respective corresponding winding mechanisms by their respective guide rollers 6.

[0047] Further preferably, the A-side anode strip 1 and the B-side anode strip 3 both have metallic lithium 20 attached to one side of the conductive strip 30, and a layer of isolation film 10 is introduced into the side of the A-side anode strip 1 or the B-side anode strip 3 having the metallic lithium 20, and the side of the A-side anode strip 1 or the B-side anode strip 3 having the isolation film 10 is bonded to the front side of the lithium-replenished negative electrode sheet 100.

[0048] Further preferably, a layer of isolation film 10 is introduced into the lithium-replenished negative electrode sheet 100 before entering the incoming material receiving roller 101, and is arranged on the reverse side of the lithium-replenished negative electrode sheet 100. The B-side anode strip 3 / A-side anode strip 1 has a side with metallic lithium 20 that is bonded to the isolation film 10 arranged on the reverse side of the lithium-replenished negative electrode sheet 100.

[0049] In this embodiment, the A-side anode strip 1 and the B-side anode strip serve as mobile anodes, composited with lithium metal 20 or a lithium compound on a copper mesh substrate. The thickness can be adjusted to 0.5 μm, with separate A / B-side dual anode coils. The dual anode unwinding mechanism, consisting of an unwinding roller, a conductive roller, a plating bath, and a rewinding roller, is synchronized with the negative electrode sheet's travel speed, forming a synchronous transport system. The anode transport speed is synchronized with the negative electrode sheet, enabling continuous production. Mobile anodes address the drawbacks of fixed anodes, such as the localized lithium depletion caused by static conventional anodes. Mobile anodes continuously renew the lithium source, ensuring stable current density.

[0050] Further preferably, the negative electrode sheet 100 to be replenished with lithium forms a stacked structure in the plating bath 300 , and the stacked structure is composed of a conductive tape 30 , metallic lithium 20 , an isolation film 10 , a pre-lithiation electrode sheet 2 , an isolation film 10 , metallic lithium 20 , and a conductive tape 30 in sequence.

[0051] The above implementation process demonstrates that the A / B side anode strips contact the conductive rollers of various electroplating current circuits before entering the plating bath 300. The negative electrode sheet 100 to be replenished also contacts the corresponding conductive rollers before entering the plating bath 300. After entering the plating bath 300, the positive electrode of the electroplating power source passes through the conductive rollers, the anode strips, the electrolyte, the negative electrode sheet, the conductive rollers, and finally the negative electrode of the electroplating power source, forming a complete electroplating current circuit. Because a separator 10 separates the lithium metal 20 or lithium compound from the negative electrode sheet, direct contact between the positive and negative electrodes is avoided. The separator 10 is fully immersed in the electrolyte within the plating bath 300, allowing free lithium ions, after ionization and deintercalation from the anode, to freely travel within the separator 10. Under the action of the electroplating power source, the positively charged lithium ions can be smoothly embedded in the active material of the negative electrode sheet, forming a pre-lithiated electrode sheet 2 and forming a solid electrolyte interface (SEI) film on the negative electrode sheet's surface.

[0052] In order to ensure the efficiency and stability of lithium replenishment, an isolation membrane 10 is used to block direct contact between the A / B side anode strip and the negative electrode sheet, while being able to conduct lithium ions. Moreover, the thickness of the isolation membrane 10 is thin, so that the vertical distance between the A / B side anode strip and the negative electrode sheet is the shortest. During the electroplating process, the shorter the vertical distance between the anode and cathode, the higher the electroplating efficiency.

[0053] As a preferred implementation manner of this embodiment, a controller is further included, and the electrode conveying device, the unwinding device 200, the plating solution pool 300 and the winding device 400 are all electrically connected to the controller.

[0054] The working process of the mobile anode electrochemical pre-lithiation equipment of this embodiment is as follows: first, the A-side anode belt 1 compounded with metallic lithium 20, the negative electrode sheet 100 to be replenished with lithium, and the B-side anode belt 3 compounded with metallic lithium 20 are respectively put on their corresponding unwinding shafts, and the three are unwound at the same time. After passing through the guide roller 6 and their respective conductive rollers, the three are simultaneously gathered on the bonding roller 9 to achieve the gathering and bonding of the three, and then enter the plating solution tank 300 for lithium replenishment operation. During lithium replenishment, the metallic lithium 20 on the A / B-side anode belt is in contact with the positive electrode conductive roller to achieve contact with the positive electrode of the power source. The negative electrode sheet 100 to be replenished is electrically connected to the negative electrode of the power supply by contacting the negative electrode conductive roller, and then the power is turned on. Relying on the electrochemical reaction between the positive and negative electrodes, the lithium ions of the metallic lithium 20 pass through the solid electrolyte to move toward the negative electrode sheet to be replenished, and obtain electron reduction on the negative electrode sheet to be replenished to produce metallic lithium 20, thereby achieving continuous lithium replenishment to obtain the pre-lithiated electrode sheet 2, and then the A-side anode strip 1, the pre-lithiated electrode sheet 2 and the B-side anode strip 3 are reeled up by the reeling mechanism, and the three are reeled up at the same time through the corresponding reeling shafts of the three.

[0055] Another aspect of this embodiment discloses a lithium replenishment control method for a mobile anode electrochemical pre-lithiation device, the lithium replenishment control method comprising the following steps:

[0056] S1, the amount of lithium replenishment is adjusted by the electroplating current I and the tape speed v. Since the current efficiency needs to be considered in the actual control process , the porosity of the negative electrode As well as the effect of the plating bath temperature T on the amount of lithium replenishment, based on Faraday's law, an enhanced lithium replenishment equation is established:

[0057]

[0058]

[0059] in, To predict the amount of lithium replenishment, the unit is mg / cm². This feedforward prediction value based on electrochemical principles serves as the setting benchmark for the control system and guides the adjustment of process parameters (I, v). I is the electroplating current, the unit is A; L is the length of the plating bath, the unit is m. is the molar mass of lithium, in g / mol, representing the atomic weight of lithium, 6.94 g / mol; It represents the number of electrons transferred in the lithium ion intercalation reaction, which is an electrochemical constant and takes the value of 1; is the Faraday constant, in C / mol, with a value of 96485 C / mol; v is the tape speed, in m / min; is the current efficiency, dimensionless, indicating the effective lithium deposition ratio, usually ranging from 0 to 1. It is calculated online using a coulomb efficiency meter and is used to correct for lithium losses caused by side reactions.

[0060] is the effective area coefficient, dimensionless, representing the correction factor of porosity to reaction area, The value of depends on the porosity and structure of the negative electrode sheet and can be obtained through experiments and simulations; The function can solve the problem of insufficient actual reaction area of ​​the negative electrode, that is, the porous electrode, and the porosity Related, it is used to adjust the current density during the lithium replenishment process and compensate for the actual reaction area of ​​the porous electrode, thereby improving the lithium replenishment efficiency and battery performance to ensure full utilization of the actual reaction area;

[0061] The effective reaction area, in cm², is the equivalent area actually participating in the electrochemical reaction, and is also the surface area actually participating in the lithium ion embedding. Non-linear growth, ;

[0062] is the nominal geometric area of ​​the negative electrode in cm², ignoring the surface area of ​​the pore structure. It represents a fixed parameter of the device and is determined by the electrode width and the length of the plating bath. cm²;

[0063] Porosity is dimensionless and ranges from 0 to 1. It represents the ratio of pore volume to total volume, i.e., the ratio of pore volume in active material. It ranges from 0.2 to 0.6. Usually, the value of graphite negative electrode is 0.3 to 0.4, and the value of silicon-carbon negative electrode is 0.4 to 0.6.

[0064] is the shape factor of the negative electrode material, dimensionless, and is a pore connectivity parameter that reflects the connectivity and tortuosity of the pores and is determined by SEM image analysis; usually and the thickness of the electrode coating Related, satisfying relationship ,in is the coating thickness, unit , represents the thickness of the coating formed by the negative electrode material on the surface of the current collector; is the material coefficient, which is related to the type of active material of the negative electrode material. For example, the value of graphite negative electrode is 0.05, and the value of silicon-carbon negative electrode is 0.03. This embodiment uses silicon-carbon negative electrode, and its coating thickness is =0.03, calculate =0.03× ;

[0065] Now you can calculate =1- , the porosity of the silicon-carbon negative electrode is 48%, , indicating that only about 12% of the geometric area participates in the reaction.

[0066] In addition, the current efficiency It mainly involves three key parameters: plating bath temperature, electrolyte concentration and plating current. The regression model of updated current efficiency is:

[0067]

[0068] Where T is the plating bath temperature, i.e., the electrolyte temperature, which is set in the linear region of 20-40°C. It represents the temperature that affects the ion migration rate and reaction kinetics. That is, the higher the temperature, the greater the lithium ion mobility and the lower the side reaction of hydrogen evolution / SEI decomposition. I is the electroplating current, which represents the electroplating current density. The larger the current, the greater the overpotential, and the greater the side effect of hydrogen evolution / SEI decomposition. is the electrolyte concentration, ranging from 0.8 to 1.2 mol / L. The higher the concentration, the greater the conductivity and the smaller the concentration polarization. Indicates the basic current efficiency under ideal conditions, usually ranging from 0.92 to 0.95; Indicates the temperature positive effect coefficient, usually ranging from +0.002 to +0.005; Indicates the current negative effect coefficient, usually ranging from -0.0003 to -0.001; Indicates the concentration positive effect coefficient, usually ranging from +0.08 to +0.15; Represents the high temperature attenuation coefficient, usually -0.0001 (T>40℃); the fitting coefficient is updated by recursive least squares method , to adapt to different batches of electrolyte, through this model, it can adapt to different production batches such as porosity fluctuations of ±15% and environmental changes such as temperature fluctuations of ±5℃, and maintain the lithium replenishment accuracy within ±1%.

[0069] It is worth mentioning that the separator 10 only serves as a lithium ion transmission channel and does not participate in the electrochemical reaction. Its porosity affects the ionic conductivity and is implicit in the current efficiency. In, through Function is indirectly reflected.

[0070] S2. In order to accurately replenish lithium and ensure equipment safety, an objective function is introduced. The objective function needs to include the optimization of the deviation of the system state quantity and the control quantity, and the model predictive control algorithm is used for dynamic compensation. The objective function Satisfaction relationship:

[0071]

[0072] in, To predict the amount of lithium supplementation; The target amount of lithium supplementation; The voltage change rate is controlled to prevent unsafe side reactions during the charge and discharge process of the battery, such as the formation of lithium dendrites. The safety-accuracy trade-off coefficient is typically between 0.1 and 0.3. By adjusting the safety-accuracy trade-off coefficient, a balance is found between lithium replenishment accuracy and process safety, thereby balancing lithium replenishment accuracy and voltage stability.

[0073] In the above objective function , as the deviation term of lithium supplementation amount, the actual lithium supplementation amount Get as close to your target lithium intake as possible , accurately controlling the amount of lithium replenishment, which is the main goal of control. This item represents the penalty for the deviation of the lithium replenishment amount. The square error is used to accurately control the amount of lithium replenishment. By minimizing the deviation of the lithium replenishment amount, the accurate insertion and extraction of lithium ions during the charge and discharge process of the battery is ensured; Represents the voltage fluctuation penalty, which is used to maintain electrochemical stability and prevent lithium dendrites and side reactions.

[0074] It is also particularly mentioned that It is the result of measurement or estimation, which is used as the feedback of the control system. The actual amount of lithium replenishment is set to Since the actual amount of lithium replenishment cannot be obtained in real time and is usually delayed, the theoretical prediction value is used. As an estimate of the actual value, and used in the objective function, in practical applications, by controlling the electroplating current I and the tape speed v, the theoretical prediction value Tracking target value , and by utilizing the actual amount of lithium replenishment Feedback correction is used to modify the regression model η of current efficiency to improve the accuracy of theoretical prediction.

[0075] Set the constraints of the objective function: , , , , solve the objective function and output the optimal (I, v) combination;

[0076] in, and are the minimum and maximum allowable values ​​of the electroplating current, respectively. In this embodiment, the electroplating current I should be limited to =10A and = between 200A; is the voltage, The voltage safety threshold is set to limit the voltage to not exceed the safety threshold to prevent the electrolyte from decomposing. =4.55V; The minimum and maximum allowable values ​​of the tape speed are respectively. In order to ensure the response time, =0.5m / min, and within the equipment limit =10m / min; is the minimum value of current efficiency, in this embodiment ;

[0077] This embodiment uses the model predictive control algorithm to solve the optimal (I, v) combination based on the given equations and parameters above, and outputs the optimal parameters I=150A, v=4.2m / min. That is, the electroplating power supply adjusts the current to 150A, the servo motor adjusts the tape speed to 4.2m / min, the controller sends the optimal parameter instruction, and the actuator starts to execute the instruction.

[0078] S3. The controller sends the optimal (I, v) combination of new parameters to the actuator. After the actuator executes the command, it monitors the device status in real time.

[0079] S4, the sensor collects data in real time, and the random forest classifier extracts features based on the collected real-time data. The features are voltage , voltage change rate , current efficiency , the concentration gradient of lithium ions Δ[Li +] and anode impedance Ra, match the corresponding fault mode through feature combination, and determine whether the match triggers protection action or returns to normal signal.

[0080] In a further preferred embodiment, the process of matching the corresponding fault mode by the feature combination in step S4 and determining whether the match triggers the protection action or returns the normal signal is as follows:

[0081] The first fault mode is lithium dendrite growth, and the characteristic combination corresponding to the first fault mode is the voltage change rate. The concentration gradient of lithium ions increases and the concentration gradient of lithium ions increases. + ] drops, and after matching, the protection action is triggered, reducing the electroplating current to a safe current of 10A and starting the acoustic oscillation to destroy the dendrite growth;

[0082] The above matching diagnostic conditions are satisfied at the same time: the concentration gradient of lithium ions Δ[Li + ]>1.2mol / L / cm and the voltage mutation amplitude>0.15V; the concentration gradient of lithium ions is essentially the local concentration difference max(Δ[Li + ])-min(Δ[Li + ]).

[0083] The second fault mode is anode passivation. The characteristic combination corresponding to the second fault mode is an increase in anode impedance Ra and a decrease in current efficiency η. After matching, the protection action is triggered, and a reverse pulse is applied to try to eliminate the passivation layer and the temperature is raised to 40°C to increase the reaction activity.

[0084] The above matching diagnostic conditions are met at the same time: Impedance growth rate >150%, , the decrease rate of current efficiency η is greater than 20%;

[0085] The third fault mode is that the isolation membrane 10 is blocked. The characteristic combination corresponding to the third fault mode is that the voltage U increases and the current I decreases. The protection action triggered after the match is to shut down the machine and start ultrasonic cleaning to remove the blockage.

[0086] The above matching diagnostic conditions are met at the same time: the absolute rise value of the voltage , electroplating current I decrease rate> 15%;

[0087] When none of the above three fault modes are matched, it is determined that there is no fault, the normal signal is returned, and the subsequent lithium replenishment operation is continued until the design requirements of the lithium replenishment amount are met and the lithium replenishment action is completed.

[0088] In summary, this embodiment provides lithium replenishment on both sides of the negative electrode sheet by providing an A-side anode strip and a B-side anode strip, respectively, thereby solving the problem of local lithium depletion that may be caused by a fixed anode and ensuring the stability of the current density and the uniformity of lithium replenishment. An isolation membrane is used between the anode strip and the negative electrode sheet to prevent direct contact while allowing lithium ions to pass through, thereby improving the lithium replenishment efficiency. The thin thickness of the isolation membrane helps to shorten the vertical distance between the cathode and anode, further improving the electroplating efficiency. A stacked structure consisting of a conductive strip, metallic lithium, an isolation membrane, and a pre-lithiated electrode sheet is formed in the plating bath, which facilitates the effective transmission and uniform embedding of lithium ions. The lithium replenishment control method adjusts the lithium replenishment amount by the electroplating current and the belt speed, taking into account factors such as current efficiency, porosity, and plating bath temperature. An enhanced lithium replenishment amount equation is established based on Faraday's law to achieve precise control. Then, a simulation predictive control (MPC) algorithm is introduced to achieve precise lithium replenishment and equipment safety by dynamically compensating for the deviation of the system state quantity and optimizing the control quantity. Sensors are used to collect data in real time, and a random forest classifier is used to extract features and match fault modes to trigger corresponding protection actions.

[0089] It should be understood that the above embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations thereof based on the present invention; the variations and modifications made by ordinary technicians in this industry through the present invention without making groundbreaking innovations all fall within the scope of protection of the present invention.

Claims

1. A mobile anode electrochemical pre-lithiation device, characterized by: It includes a pole piece conveying device, an unwinding device, a first guide assembly, a plating solution tank, a second guide assembly and a winding device connected in sequence. The unwinding device includes an unwinding seat, an unwinding main board, a first unwinding mechanism and a second unwinding mechanism installed on the unwinding main board, the unwinding main board is arranged on the unwinding seat, the first unwinding mechanism is used to convey the A-side anode strip, and the second unwinding mechanism is used to convey the B-side anode strip. The electrode sheet conveying device conveys the negative electrode sheet to be replenished with lithium to the incoming material receiving roller arranged on the unwinding main board to form a electrode sheet conveying line, and the electrode sheet conveying line is located between the first unwinding mechanism and the second unwinding mechanism; the A-side anode strip and the B-side anode strip are both attached with metallic lithium on one side of the conductive strip, and a layer of isolation film is introduced into the side of the A-side anode strip or the B-side anode strip with metallic lithium, and the side of the A-side anode strip or the B-side anode strip with the isolation film is bonded to the front side of the negative electrode sheet to be replenished with lithium; The first guide assembly includes a guide roller, a pole piece conductive roller, a first conductive roller, a second conductive roller and a bonding roller. The negative electrode sheet to be replenished with lithium passes through the guide roller and the pole piece conductive roller in sequence after the incoming material receiving roller. The A-side anode strip passes through the guide roller and the first conductive roller in sequence after the first unwinding mechanism. The B-side anode strip passes through the guide roller and the second conductive roller in sequence after the second unwinding mechanism. After the negative electrode sheet to be replenished with lithium, the A-side anode strip and the B-side anode strip are gathered together, they pass through the bonding roller and enter the plating bath for lithium replenishment operation; During lithium replenishment, the metallic lithium on the A / B side anode belt is electrically connected to the positive electrode of the power supply by contacting the positive electrode conductive roller, and the negative electrode sheet to be replenished is electrically connected to the negative electrode of the power supply by contacting the negative electrode conductive roller. Then the power is turned on, and relying on the electrochemical reaction between the positive and negative electrodes, the lithium ions of the metallic lithium pass through the solid electrolyte to move to the negative electrode sheet to be replenished, and obtain electron reduction on the negative electrode sheet to be replenished to produce metallic lithium, thereby realizing continuous lithium replenishment to obtain pre-lithiated sheets. Then, the A side anode belt, the pre-lithiated sheet and the B side anode belt are reeled up by the reeling mechanism, and the three are reeled up at the same time through the corresponding reeling shafts of the three.

2. The mobile anode electrochemical pre-lithiation device according to claim 1, characterized in that: The winding device includes a winding seat, a winding main board, a pole piece winding mechanism, a first winding mechanism and a second winding mechanism. The winding main board stands on the winding seat. The first winding mechanism is used for winding the A-side anode strip, and the second unwinding mechanism is used for winding the B-side anode strip. The pole piece winding mechanism is arranged between the first winding mechanism and the second winding mechanism, and both are installed on the winding main board; the second guide assembly includes a bonding roller and a guide roller. After the pre-lithiation pole piece, the A-side anode strip and the B-side anode strip come out of the plating bath together, they pass through the bonding roller and are then connected to their corresponding winding mechanisms by their respective guide rollers.

3. The mobile anode electrochemical pre-lithiation device according to claim 1, characterized in that: The lithium-replenished negative electrode sheet is introduced with a layer of isolation film before entering the incoming material receiving roller, and is arranged on the reverse side of the lithium-replenished negative electrode sheet. The B-side anode strip / A-side anode strip has a side with metallic lithium and is bonded to the isolation film arranged on the reverse side of the lithium-replenished negative electrode sheet.

4. The mobile anode electrochemical pre-lithiation device according to claim 3, characterized in that: The negative electrode sheet to be replenished with lithium forms a stacked structure in the plating bath, and the stacked structure is sequentially composed of a conductive strip, metallic lithium, an isolation film, a pre-lithiated electrode sheet, an isolation film, metallic lithium, and a conductive strip.

5. The mobile anode electrochemical pre-lithiation device according to claim 1, characterized in that: It also includes a controller, and the electrode conveying device, unwinding device, plating solution pool and winding device are all electrically connected to the controller.

6. A lithium replenishment control method, characterized in that: For any mobile anode electrochemical pre-lithiation device according to claims 1 to 5, the lithium replenishment control method comprises the following steps: S1, lithium replenishment amount through electroplating current I and tape speed v Adjustment is performed because the current efficiency needs to be considered in the actual control process , the porosity of the negative electrode and bath temperature T The impact on the amount of lithium replenishment is based on Faraday's law and the enhanced lithium replenishment equation is established: ； in To predict the amount of lithium supplementation, the unit is mg / cm; I is the electroplating current, unit is A; is the length of the plating bath, in m; is the molar mass of lithium, in g / mol; Represents the number of electrons transferred in the lithium ion intercalation reaction; is the Faraday constant, unit is C / mol; v is the tape speed, in m / min; is the current efficiency, dimensionless; is the effective area coefficient, dimensionless; is the effective reaction area, in cm²; is the nominal geometric area of ​​the negative electrode sheet, in cm²; is the porosity, dimensionless; is the shape factor of the negative electrode material, dimensionless; S2. Introduce the objective function. The objective function needs to include the optimization of the deviation of the system state quantity and the control quantity, and use the model predictive control algorithm for dynamic compensation. Its objective function Satisfaction relationship: in, To predict the amount of lithium supplementation; The target amount of lithium supplementation; is the voltage change rate; is the safety-accuracy trade-off coefficient; Set the constraints of the objective function: , , , , solve the objective function and output the optimal (I, v) combination; in, and are the minimum and maximum allowable values ​​of electroplating current respectively; is the voltage, is the voltage safety threshold; They are the minimum and maximum allowable values ​​of the tape speed respectively; is the minimum value of current efficiency; S3. The controller sends the optimal (I, v) combination of new parameters to the actuator. After the actuator executes the command, it monitors the device status in real time. S4, the sensor collects data in real time, and the random forest classifier extracts features based on the collected real-time data. The features are voltage , voltage change rate , current efficiency , the concentration gradient of lithium ions Δ[Li + ] and anode impedance Ra, match the corresponding fault mode through feature combination, and determine whether the match triggers protection action or returns to normal signal.

7. The lithium replenishment control method according to claim 6, characterized in that: The process of matching the corresponding fault mode by the feature combination in step S4 and determining whether the match triggers the protection action or returns the normal signal is as follows: The first fault mode is lithium dendrite growth, and the characteristic combination corresponding to the first fault mode is the voltage change rate. The concentration gradient of lithium ions increases and the concentration gradient of lithium ions increases. + ]decline; The second fault mode is anode passivation, and the characteristic combination corresponding to the second fault mode is an increase in anode impedance Ra and a decrease in current efficiency η; The third fault mode is the blocking of the isolation membrane, and the characteristic combination corresponding to the third fault mode is the voltage U rising and the current I falling; When none of the above three fault modes are matched, it is judged as no fault and a normal signal is returned.

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