Sodium-chloride-nickel battery pack equalization charging and discharging control method based on intelligent algorithm

Abstract

The application relates to the technical field of battery management, in particular to a sodium-chlorine nickel battery pack equalization charging and discharging control method based on an intelligent algorithm. The method comprises the following steps: acquiring working parameters of each single battery of the battery pack and controlling the temperature to a preset range; detecting sodium and nickel ion concentration parameters of each single battery, calculating a sodium ion transmission rate, and determining a charging and discharging rate parameter; calculating a state of charge value and a state of health value based on the working parameters and the rate parameter, determining a charging and discharging time and a strategy, so that the battery pack is equalized in charging and discharging. The method can improve the charging and discharging efficiency of the sodium-chlorine nickel battery pack, prolong the service life, and ensure the safe and stable operation of the battery pack.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and in particular to a method for equalizing charge and discharge control of sodium nickel chloride battery packs based on intelligent algorithms. Background Technology

[0002] With the rapid development of new energy technologies, sodium nickel chloride (CNC) batteries, with their advantages of high energy density, long cycle life, and environmental friendliness and safety, have shown broad application prospects in fields such as power storage and new energy vehicles. As a novel type of rechargeable battery, CNC batteries work by utilizing the redox reaction between sodium and nickel ions to store and release electrical energy. To improve the overall performance and lifespan of CNC battery packs, balanced charge-discharge control technology has become a key research direction.

[0003] Currently, there are still some technical challenges in the equalization charge and discharge control technology of nickel-sodium chloride (NiCl3) battery packs. Traditional battery equalization control methods cannot effectively adapt to the electrochemical characteristics of NiCl3 batteries, making it difficult to accurately adjust the charge and discharge strategy based on changes in the concentration of sodium and nickel ions within the battery. This leads to imbalances among individual cells in the battery pack, shortening the overall lifespan of the battery pack. Existing technologies lack precise temperature control mechanisms for NiCl3 batteries, while their electrochemical performance is closely related to temperature. Improper temperature control can lead to a decrease in ion transport efficiency within the battery, reducing its charge and discharge performance. Existing technologies cannot accurately assess the state of charge and health of individual cells in a NiCl3 battery pack, and cannot dynamically adjust the charge and discharge strategy based on the actual state of the battery. This prevents the overall performance of the battery pack from reaching its optimal state, affecting its efficiency and lifespan. Summary of the Invention

[0004] This invention provides a method for equalizing charge and discharge control of sodium nickel chloride battery packs based on intelligent algorithms, which can at least solve some of the problems existing in the prior art.

[0005] A first aspect of the present invention provides a method for equalizing charge and discharge control of a sodium-nickel chloride battery pack based on an intelligent algorithm, comprising:

[0006] The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature of the individual cell is controlled to reach a preset operating temperature range based on the operating parameters.

[0007] The sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells are detected. The sodium ion transport rate of each individual cell is calculated based on the sodium ion concentration parameters and the nickel ion concentration parameters. The charge / discharge rate parameters of each individual cell are determined based on the sodium ion transport rate.

[0008] Based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated, and the charge / discharge time of the sodium-nickel chloride battery pack is determined based on the SOC values.

[0009] The charging and discharging strategy of the nickel chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel chloride battery pack is controlled to perform balanced charging and discharging based on the charging and discharging strategy.

[0010] Obtaining the operating parameters of each individual cell in a nickel-sodium chloride battery pack, and controlling the temperature of each individual cell to reach a preset operating temperature range based on the operating parameters, includes:

[0011] The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature change rate, voltage change rate and electrochemical impedance of each individual cell are calculated based on the operating parameters.

[0012] Based on the temperature parameter in the working parameters, determine whether each individual cell is within the preset temperature range, and calculate the temperature deviation value and temperature gradient value of each individual cell;

[0013] The individual cells are classified based on the temperature deviation value, the temperature gradient value, and the electrochemical impedance. The heating priority of each individual cell is calculated, and the initial heating power and heating plate power adjustment coefficient of each individual cell are determined according to the heating priority.

[0014] When the rate of temperature change is less than a preset temperature response threshold and the rate of voltage change is less than a preset voltage fluctuation threshold, the heating power of the heating plate adjacent to the single battery cell is increased according to the heating plate power adjustment coefficient.

[0015] When the internal resistance parameter in the operating parameters increases, the heating power of the heating plate is reduced until the temperature parameter of the single cell reaches the preset temperature range and the internal resistance parameter remains stable.

[0016] The process involves detecting the sodium ion concentration and nickel ion concentration parameters inside each individual battery cell, calculating the sodium ion transport rate of each individual battery cell based on the sodium ion concentration and nickel ion concentration parameters, and determining the charge / discharge rate parameters of each individual battery cell based on the sodium ion transport rate, including:

[0017] Obtain the sodium ion concentration parameters and nickel ion concentration parameters inside a single cell that has reached a preset temperature range, and calculate the lateral concentration gradient value and the longitudinal concentration gradient value inside the single cell.

[0018] Based on the lateral concentration gradient value and the longitudinal concentration gradient value, the ion diffusion coefficient inside the single cell is calculated, and the sodium ion transport rate of the single cell on the inner surface of the solid electrolyte ceramic tube is determined according to the ion diffusion coefficient.

[0019] Monitor the potential difference and ion conductivity of the inner surface of the solid electrolyte ceramic tube of the single cell, and calculate the ion migration resistance coefficient of the single cell based on the crystal orientation and grain boundary density of the inner surface of the solid electrolyte ceramic tube.

[0020] The ion migration rate of the single cell is calculated based on the potential difference, the ion conductivity and the ion migration resistance coefficient, and the ratio of the sodium ion transport rate to the ion migration rate is taken as the ion transport efficiency of the single cell.

[0021] The effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value, and the charge / discharge rate parameter of the single cell is calculated based on the effective ion transport rate.

[0022] The effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value. The charge / discharge rate parameters of the single cell are then calculated based on the effective ion transport rate, including:

[0023] The ion migration path length of the single cell is calculated based on the cross-sectional area and wall thickness of the solid electrolyte ceramic tube of the single cell, and the structural factor of the single cell is determined based on the ion migration path length.

[0024] The grain orientation angle and grain boundary density of the solid electrolyte ceramic tube surface of the single cell are obtained, the interfacial polarization impedance of the single cell is calculated, and the ion flux loss coefficient of the single cell is determined based on the interfacial polarization impedance.

[0025] Monitor the solid-liquid interface capacitance and electrolyte conductivity of the single cell, calculate the ion diffusion channel coefficient of the single cell, and determine the mass transfer loss coefficient of the single cell based on the ion diffusion channel coefficient.

[0026] The product of the ion transport efficiency and the concentration gradient value is used as the initial transport rate. The initial transport rate is then corrected according to the structure factor, the ion flux loss coefficient, and the mass transfer loss coefficient to obtain the effective ion transport rate of the single cell. The charge / discharge rate parameter of the single cell is then calculated based on the effective ion transport rate.

[0027] Based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated. The charge / discharge time of the sodium-nickel chloride (NiCC) battery pack is determined based on the SOC values, including:

[0028] The polarization resistance and ohmic resistance of the solid electrolyte ceramic tube surface of the single cell are monitored, the internal resistance change rate of the single cell is calculated, the coulombic efficiency of the single cell is calculated based on the operating parameters, and the coulombic efficiency is corrected based on the internal resistance change rate to obtain the corrected coulombic efficiency of the single cell.

[0029] The cycle number and operating time of the single cell are obtained, the capacity decay rate of the single cell is calculated, and the health status value of the single cell is determined based on the corrected coulombic efficiency and the capacity decay rate.

[0030] The remaining capacity and total capacity of the individual battery are determined based on the operating parameters and the charge / discharge rate parameters, and the state of charge value of the individual battery is determined based on the remaining capacity and the total capacity.

[0031] The effective capacity coefficient of the individual battery is determined based on the state of charge value and the state of health value. The difference between the maximum and minimum effective capacity coefficients in the sodium nickel chloride battery pack is calculated, and the charge and discharge time of the sodium nickel chloride battery pack is determined based on the difference.

[0032] The charging and discharging strategy of the nickel-sodium chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel-sodium chloride battery pack is controlled to perform equal charging and discharging based on the charging and discharging strategy, including:

[0033] The charging impedance and discharging impedance of the single cell are determined, the charging and discharging polarization coefficient of the single cell is determined based on the charging impedance and the discharging impedance, and the charging and discharging power of the single cell is determined according to the sodium ion concentration parameter and nickel ion concentration parameter of the single cell.

[0034] The individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient and the charge / discharge power, and the charge / discharge strategy of the sodium nickel chloride battery pack is determined based on the grouping results.

[0035] According to the charging and discharging strategy, the sodium-nickel chloride battery pack is controlled to perform equal charging, the sodium ions in the second electrolyte are controlled to be transported to the inner surface of the solid electrolyte ceramic tube, the sodium chloride in the positive electrode material is controlled to dissociate into sodium ions and chloride ions, the sodium ions are added to the second electrolyte, and the chloride ions react with nickel ions to generate nickel chloride.

[0036] When the state of charge of the single cell is detected to reach a preset charging threshold, liquid sodium metal is controlled to lose electrons to generate sodium ions. The sodium ions are then controlled to be transported from the outside of the ceramic tube to the inner surface of the ceramic tube and combine with chloride ions to generate sodium chloride. Meanwhile, nickel ions are controlled to gain electrons to generate metallic nickel, thereby controlling the sodium-nickel chloride battery pack to perform balanced discharge.

[0037] The individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient, and the charge / discharge power. Based on the grouping results, a charge / discharge strategy for the sodium-nickel chloride battery pack is determined, including:

[0038] The individual cells are divided into different charge groups according to the distribution range of the state of charge values; the remaining life of the individual cells is calculated based on the state of health values, and the individual cells in different charge groups are divided into different degradation groups based on the remaining life.

[0039] The ion diffusion coefficient and ion conductivity of the solid electrolyte ceramic tube surface of the single cell are monitored. The ion migration rate of the single cell is calculated based on the ion diffusion coefficient and the ion conductivity. The polarization coefficient of the charge and discharge polarization is corrected based on the ion migration rate to obtain the polarization correction coefficient of the single cell.

[0040] The solid-liquid interface capacitance and electrolyte conductivity of the single cell are obtained. The ion transport flux of the single cell is calculated based on the solid-liquid interface capacitance and electrolyte conductivity. The charge and discharge power is corrected based on the ion transport flux to obtain the power correction coefficient of the single cell.

[0041] The individual cells within the attenuation group are regrouped based on the polarization correction coefficient and the power correction coefficient to obtain multiple charge-discharge groups. The charge-discharge strategy of the sodium-nickel chloride battery pack is determined based on the distribution of the multiple charge-discharge groups.

[0042] A second aspect of the present invention provides a sodium-nickel chloride battery pack equalization charge-discharge control system based on intelligent algorithms, comprising:

[0043] The first unit is used to acquire the operating parameters of each individual cell in the sodium nickel chloride battery pack, and control the temperature of the individual cell to reach a preset operating temperature range based on the operating parameters.

[0044] The second unit is used to detect the sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells, calculate the sodium ion transport rate of each individual cell based on the sodium ion concentration parameters and the nickel ion concentration parameters, and determine the charge / discharge rate parameters of each individual cell based on the sodium ion transport rate.

[0045] The third unit is used to calculate the state of charge and state of health values ​​of each individual battery cell based on the operating parameters and the charge / discharge rate parameters, and to determine the charge / discharge time of the sodium-nickel chloride battery pack based on the state of charge values.

[0046] The fourth unit is used to determine the charging and discharging strategy of the nickel-sodium chloride battery pack based on the state of charge value and the state of health value, and to control the nickel-sodium chloride battery pack to perform equal charging and discharging based on the charging and discharging strategy.

[0047] A third aspect of the present invention provides an electronic device, comprising:

[0048] processor;

[0049] Memory used to store processor-executable instructions;

[0050] The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0051] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0052] This invention obtains the operating parameters of each individual cell in the sodium nickel chloride battery pack and controls the temperature to reach a preset range, ensuring that the battery pack operates under optimal temperature conditions, effectively improving the charging and discharging efficiency and service life of the battery.

[0053] By detecting sodium and nickel ion concentration parameters to calculate the transmission rate and determining the charge / discharge rate parameters accordingly, precise control of the internal electrochemical reaction of the battery is achieved. This solves the problem that traditional control methods cannot adapt to the characteristics of sodium-nickel chloride batteries and improves the charge / discharge performance of the battery pack.

[0054] This invention determines the charging and discharging strategy and performs equalization control based on the state of charge and state of health values, effectively avoiding inconsistencies between individual cells in the battery pack, extending the cycle life of the battery pack, and improving the overall energy utilization and operational safety of the battery pack. Attached Figure Description

[0055] Figure 1 This is a flowchart illustrating the equalization charge and discharge control method for sodium nickel chloride battery packs based on intelligent algorithms, according to an embodiment of the present invention.

[0056] Figure 2 This is a schematic flowchart illustrating the calculation of charge / discharge rate parameters of a single battery cell according to an embodiment of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0059] Figure 1 This is a flowchart illustrating the equalization charge and discharge control method for sodium-nickel chloride battery packs based on intelligent algorithms, according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0060] The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature of the individual cell is controlled to reach a preset operating temperature range based on the operating parameters.

[0061] The sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells are detected. The sodium ion transport rate of each individual cell is calculated based on the sodium ion concentration parameters and the nickel ion concentration parameters. The charge / discharge rate parameters of each individual cell are determined based on the sodium ion transport rate.

[0062] Based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated, and the charge / discharge time of the sodium-nickel chloride battery pack is determined based on the SOC values.

[0063] The charging and discharging strategy of the nickel chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel chloride battery pack is controlled to perform balanced charging and discharging based on the charging and discharging strategy.

[0064] This invention achieves balanced charging and discharging and performance optimization of battery packs by precisely controlling the temperature of individual cells, monitoring ion concentration, calculating transmission rate, and determining charging and discharging strategies.

[0065] The operating parameters of each individual cell in the sodium nickel chloride battery pack include battery voltage, current, internal resistance, and temperature. These parameters can be collected through a distributed sensor network with a sampling frequency set to 100Hz to ensure real-time and accurate data acquisition. The collected data undergoes low-pass filtering to remove high-frequency noise and improve signal quality. Taking a 32-cell, 10-parallel battery pack as an example, the collected individual cell voltage ranges from 2.8V to 3.6V, the operating current is -20A to +20A (negative values ​​indicate discharge, positive values ​​indicate charging), the internal resistance is 5mΩ to 15mΩ, and the initial temperature is 15℃ to 35℃.

[0066] Based on the obtained operating parameters, the temperature of each individual battery needs to be controlled to reach the preset operating temperature range. The optimal operating temperature range for sodium nickel chloride batteries is 25℃ to 40℃. Within this temperature range, the battery's chemical reaction rate is moderate, and its ion conduction performance is optimal. Temperature control is achieved using a liquid cooling system combined with an active heating device. The liquid cooling system consists of a high-efficiency coolant, a microchannel cold plate, and a variable-speed circulating pump, with a cooling capacity of up to 1500W. When the temperature of a single battery exceeds 40℃, the coolant flow rate is increased to accelerate heat dissipation; when the temperature is below 25℃, the thin-film heater integrated at the bottom of the battery is activated, with a heating power adjustable from 200W to 500W, and the heating rate is controlled within 5℃ / minute to avoid internal stress caused by excessive temperature gradients. The temperature control accuracy reaches ±1℃, ensuring that the battery operates within the optimal temperature range.

[0067] After the battery reaches its suitable operating temperature, the sodium and nickel ion concentrations within each individual cell are measured. The measurement employs electrochemical impedance spectroscopy combined with characteristic frequency analysis. By applying a small-amplitude AC signal across the battery terminals, the impedance response at different frequencies is analyzed to indirectly obtain the internal ion concentration status. Sodium ion concentrations typically range from 0.5 mol / L to 2.5 mol / L, and nickel ion concentrations range from 0.1 mol / L to 0.8 mol / L. In actual measurements, the scanning frequency range is 0.01 Hz to 10 kHz, acquiring impedance values ​​at different frequency points. The ion concentration distribution is then calculated by analyzing the impedance variation trends at characteristic frequency points.

[0068] The sodium ion transport rate can be calculated based on the measured sodium ion concentration parameters and nickel ion concentration parameters. The sodium ion transport rate can also be calculated by analyzing the polarization characteristics of the battery under different current densities and combining the ion concentration gradient.

[0069] The charge / discharge rate parameters for each individual battery cell can be determined based on the sodium ion transport rate. The charge / discharge rate directly affects the battery's charge / discharge efficiency and lifespan. A safe and efficient charge / discharge rate can be determined by combining the calculated sodium ion transport rate with the battery capacity and electrode material characteristics. For individual batteries with higher transport rates, the charge / discharge rate can be appropriately increased; for individual batteries with lower transport rates, the charge / discharge rate should be decreased to avoid over-polarization. In one example, with a battery capacity of 100 Ah, when the sodium ion transport rate is 3 × 10⁻⁶ mol / (cm²·s), the optimal charge rate is determined to be 0.5C (i.e., 50A), and the discharge rate is 1C (i.e., 100A). When the transport rate is increased to 4 × 10⁻⁶ mol / (cm²·s), the charge rate can be increased to 0.8C (80A), and the discharge rate to 1.5C (150A).

[0070] Based on operating parameters and charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell can be calculated. The SOC calculation employs an improved coulombometry method combined with an open-circuit voltage correction method, integrating current integration with the open-circuit voltage characteristic curve to improve estimation accuracy. The SQH value is comprehensively evaluated through three dimensions: capacity retention rate, internal resistance growth rate, and charge / discharge efficiency. First, the open-circuit voltage characteristic points of the battery at different SOC states are recorded, such as 2.8V for 0% SOC, 3.0V for 25% SOC, 3.2V for 50% SOC, 3.4V for 75% SOC, and 3.6V for 100% SOC. In actual operation, the current can be integrated in real time, and accumulated errors can be corrected using open-circuit voltage at appropriate times. In the health status value calculation, the new battery has a capacity retention rate of 100%, an internal resistance growth rate of 0%, and a charge / discharge efficiency of over 95%, with a comprehensive score of 100 points. As the number of cycles increases, when the capacity retention rate drops to 80%, the internal resistance growth rate reaches 50%, and the charge / discharge efficiency drops to 85%, the health status value drops to 70 points, indicating a significant decline in battery performance.

[0071] The charge and discharge times of a nickel-sodium chloride (NiCC) battery pack can be determined based on its state of charge (SOC). The charging time calculation considers the battery's current SOC, charging rate, charging efficiency, and capacity. A two-stage charging strategy—constant current followed by constant voltage—can be employed. Taking a 100Ah battery pack as an example, when the SOC is 20%, 80% of the capacity needs to be charged. At a 0.5C rate and considering 90% charging efficiency, the constant current stage charging time is approximately 96 minutes. In the constant voltage stage, the current gradually decreases, and charging the remaining 10% of the capacity takes approximately 30 minutes, for a total charging time of 126 minutes. The discharge time calculation is based on the discharge rate and available capacity. When the SOC is 100% and the discharge rate is 1C, the theoretical discharge time is 60 minutes. Considering battery polarization and temperature effects, the actual usable time is approximately 55 minutes.

[0072] The charging and discharging strategy for nickel-sodium chloride (NiCl3) battery packs can be determined based on their state of charge (SOC) and state of health (SOC) values. An adaptive charging and discharging strategy can be adopted based on the differences between individual cells. For cells with higher SOC values, a wider SOC operating range is allowed, such as 10%-90%; for cells with lower SOC values, the SOC operating range is narrowed, such as 20%-80%, to slow down their degradation rate. The charging strategy employs a staged charging method: a higher charging rate is used in the initial stage (0%-50% SOC), the rate is reduced in the intermediate stage (50%-80% SOC), and the rate is further reduced in the final stage (80%-100% SOC). In a certain battery pack, cells with a SOC value of 95 are allowed to be charged at a 0.8C rate to 90% SOC; while cells with a SOC value of 75 are limited to a 0.5C rate and a maximum charge to 85% SOC.

[0073] The sodium-nickel chloride (NiCl3) battery pack can be controlled for balanced charging and discharging based on a charging and discharging strategy to optimize the overall performance of the battery pack. The balanced charging and discharging employs active balancing technology, using a distributed power electronic converter to achieve directional energy transfer between individual cells. The balancing trigger threshold is set when the voltage difference between individual cells exceeds 50mV or the state-of-charge (SOC) difference exceeds 5%. The balancing current is adjustable from 0.5A to 5A, adaptively adjusting according to the degree of imbalance. In practical applications, when a single cell voltage of 3.45V is detected while the adjacent cell voltage is 3.38V, the balancing module is activated, setting a 2A balancing current to transfer energy from the high-voltage cell to the low-voltage cell. The balancing process lasts approximately 10 minutes until the voltage difference drops to within 20mV. For individual cells that consistently show low capacity, more charging time is allocated in the next charging cycle to improve their SOC and maximize the utilization of the overall battery pack capacity.

[0074] Through the above implementation methods, comprehensive monitoring and precise control of individual battery parameters are achieved, effectively balancing battery performance and lifespan, significantly improving the energy utilization efficiency and cycle life of the battery pack, and providing technical support for the widespread application of sodium nickel chloride batteries in energy storage systems.

[0075] In one optional embodiment, the operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature of each individual cell is controlled to reach a preset operating temperature range based on the operating parameters, including:

[0076] The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature change rate, voltage change rate and electrochemical impedance of each individual cell are calculated based on the operating parameters.

[0077] Based on the temperature parameter in the working parameters, determine whether each individual cell is within the preset temperature range, and calculate the temperature deviation value and temperature gradient value of each individual cell;

[0078] The individual cells are classified based on the temperature deviation value, the temperature gradient value, and the electrochemical impedance. The heating priority of each individual cell is calculated, and the initial heating power and heating plate power adjustment coefficient of each individual cell are determined according to the heating priority.

[0079] When the rate of temperature change is less than a preset temperature response threshold and the rate of voltage change is less than a preset voltage fluctuation threshold, the heating power of the heating plate adjacent to the single battery cell is increased according to the heating plate power adjustment coefficient.

[0080] When the internal resistance parameter in the operating parameters increases, the heating power of the heating plate is reduced until the temperature parameter of the single cell reaches the preset temperature range and the internal resistance parameter remains stable.

[0081] In this embodiment, the operating parameters of each individual cell in the nickel-sodium chloride (NiCC) battery pack are first acquired. These operating parameters include, but are not limited to, battery temperature, voltage, internal resistance, and charge / discharge current. The acquisition of these operating parameters can be achieved through a sensor network installed in the battery pack. This sensor network consists of a temperature sensor, a voltage acquisition unit, and a current acquisition unit, with a sampling frequency set to twice per second to ensure timely capture of changes in battery status. For example, for a NiCC battery pack composed of 12 individual cells, each individual cell is equipped with an independent parameter acquisition device to record real-time parameters such as temperature (e.g., 270℃~350℃), terminal voltage (e.g., 2.0V~2.6V), and charge / discharge current (e.g., -20A~+20A).

[0082] Based on the acquired operating parameters, the temperature change rate, voltage change rate, and electrochemical impedance of each individual cell can be calculated. The temperature change rate is obtained by dividing the difference between two consecutive temperature samples by the sampling time interval, with units of °C / s; the voltage change rate is calculated by dividing the difference between two consecutive voltage samples by the sampling time interval, with units of V / s; and the electrochemical impedance is obtained through electrochemical impedance spectroscopy (EIS). A small AC signal is applied to the cell, and the internal electrochemical reaction state is characterized by analyzing the cell's response characteristics, with units of Ω. For example, under standard operating conditions, the temperature change rate of a single cell should typically be kept below 0.05 °C / s, the voltage change rate below 0.002 V / s, and the electrochemical impedance should be maintained within the range of 0.5~0.8 Ω at an operating temperature of 300 °C.

[0083] Then, based on the temperature parameters in the operating parameters, it is determined whether each individual battery cell is within the preset temperature range. The preset temperature range is set to 270℃~350℃ according to the characteristics of sodium nickel chloride batteries. When the temperature of an individual battery cell is below 270℃, the battery activity is insufficient and the internal resistance increases; while when the temperature is above 350℃, the battery is at risk of thermal runaway. The temperature deviation value and temperature gradient value of each individual battery cell are calculated. The temperature deviation value is the difference between the actual temperature of the individual battery cell and the center temperature of the preset temperature range (310℃); the temperature gradient value is the temperature difference between the individual battery cell and its adjacent cells. For example, when the temperature of a certain individual battery cell is 260℃, its temperature deviation value is -50℃, indicating that the temperature of this battery cell is too low; if the temperature of an adjacent cell is 280℃, the temperature gradient value is 20℃, indicating that there is significant temperature unevenness within the battery pack.

[0084] Individual cells can be classified based on temperature deviation, temperature gradient, and electrochemical impedance. The heating priority of each cell is calculated, with the following classification criteria: an absolute temperature deviation exceeding 30°C indicates a high-risk level; a temperature gradient exceeding 15°C indicates a medium-risk level; and an electrochemical impedance exceeding 1.5 times the standard value also indicates a medium-risk level. Heating priorities are determined comprehensively based on risk level and deviation degree: high-risk cells have a heating priority of 1, medium-risk cells have a heating priority of 2, and low-risk cells have a heating priority of 3. The initial heating power and heating plate power adjustment coefficient for each individual cell are determined according to the heating priority. For example, for a cell with a heating priority of 1, the initial heating power of its corresponding heating plate is set to 80% of the maximum power (if the maximum power is 500W, then the initial heating power is 400W), and the power adjustment coefficient is 0.2, meaning that the power can be increased or decreased by 20% each time during subsequent adjustments.

[0085] During temperature control, if the rate of temperature change is less than the preset temperature response threshold (e.g., 0.03℃ / s) and the rate of voltage change is less than the preset voltage fluctuation threshold (e.g., 0.001V / s), it indicates that the current heating power is insufficient to bring the battery to its ideal operating state, and the heating power needs to be increased. The heating power of the heating plate adjacent to the individual battery cell is increased according to the heating plate power adjustment coefficient. For example, for a heating plate with a power adjustment coefficient of 0.2, if the current power is 400W, the adjusted power will be 480W. After adjustment, the battery temperature and voltage change rates are continuously monitored until they reach the desired range.

[0086] When the internal resistance parameter in the operating parameters increases, it indicates that the battery temperature is too high or there are other abnormal conditions. The heating power of the heating plate needs to be reduced to prevent the battery from overheating. For example, if the internal resistance increases from 0.6Ω to 0.8Ω, the heating power should be reduced according to the power adjustment coefficient, such as from 480W to 384W. The heating power should be continuously monitored and adjusted until the temperature parameters of the individual cells reach the preset temperature range and the internal resistance parameter remains stable.

[0087] In practical applications, for a sodium-nickel chloride battery pack consisting of 12 individual cells, the initial temperature distribution of each individual cell is 250℃~330℃. Through the above control process, the temperature of all individual cells can be brought to the range of 300℃±10℃ within 30 minutes, and the internal resistance parameters are stabilized within the range of 0.6Ω±0.1Ω. This achieves uniform temperature control of the battery pack and improves the charging and discharging efficiency and cycle life of the battery pack.

[0088] This invention effectively solves the performance degradation problem caused by uneven temperature in traditional nickel-sodium chloride battery packs by precisely controlling the temperature of each individual cell in the pack and keeping them within the optimal operating temperature range, thereby improving the overall performance and lifespan of the battery pack.

[0089] In one optional embodiment, the sodium ion concentration parameter and nickel ion concentration parameter inside each of the individual cells are detected, the sodium ion transport rate of each individual cell is calculated based on the sodium ion concentration parameter and the nickel ion concentration parameter, and the charge / discharge rate parameter of each individual cell is determined based on the sodium ion transport rate, including:

[0090] Obtain the sodium ion concentration parameters and nickel ion concentration parameters inside a single cell that has reached a preset temperature range, and calculate the lateral concentration gradient value and the longitudinal concentration gradient value inside the single cell.

[0091] Based on the lateral concentration gradient value and the longitudinal concentration gradient value, the ion diffusion coefficient inside the single cell is calculated, and the sodium ion transport rate of the single cell on the inner surface of the solid electrolyte ceramic tube is determined according to the ion diffusion coefficient.

[0092] Monitor the potential difference and ion conductivity of the inner surface of the solid electrolyte ceramic tube of the single cell, and calculate the ion migration resistance coefficient of the single cell based on the crystal orientation and grain boundary density of the inner surface of the solid electrolyte ceramic tube.

[0093] The ion migration rate of the single cell is calculated based on the potential difference, the ion conductivity and the ion migration resistance coefficient, and the ratio of the sodium ion transport rate to the ion migration rate is taken as the ion transport efficiency of the single cell.

[0094] The effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value, and the charge / discharge rate parameter of the single cell is calculated based on the effective ion transport rate.

[0095] Figure 2 This is a schematic flowchart illustrating the calculation of charge / discharge rate parameters for a single battery cell according to an embodiment of the present invention. Figure 2 As shown, a single battery cell can be preheated to reach a preset temperature range, for example, by placing it in a constant temperature environment of 25°C to 35°C for 30 minutes. An ion concentration detector is used to detect the sodium and nickel ion concentration parameters inside the single battery cell after it reaches the preset temperature range. In one embodiment, the detected sodium ion concentration is 0.85 mol / L in the positive electrode region and 0.25 mol / L in the negative electrode region; the nickel ion concentration is 0.55 mol / L in the positive electrode region and 0.15 mol / L in the negative electrode region. Based on these concentration data, the lateral and longitudinal concentration gradient values ​​inside the single battery cell are calculated. The lateral concentration gradient is calculated by dividing the ion concentration difference between the positive and negative electrodes by the distance between them. For example, when the distance between the electrodes is 5 mm, the lateral concentration gradient of sodium ions is (0.85-0.25) / 0.005 = 120 mol / (L•m), and the lateral concentration gradient of nickel ions is (0.55-0.15) / 0.005 = 80 mol / (L•m). The longitudinal concentration gradient is calculated by dividing the ion concentration difference between the upper and lower parts of the battery by the longitudinal distance. For example, when the distance between the upper and lower measurement points is 10 mm, and the sodium ion concentration is 0.6 mol / L at the upper part and 0.5 mol / L at the lower part, the longitudinal concentration gradient is (0.6-0.5) / 0.01 = 10 mol / (L•m).

[0096] Based on the measured lateral and longitudinal concentration gradient values, combined with the internal temperature parameters (e.g., 28°C) and dielectric viscosity coefficient (e.g., 3.5 mPa•s), the ion diffusion coefficient inside the single cell is calculated. In this embodiment, by applying the ion diffusion model, the diffusion coefficient of sodium ions inside the single cell is calculated to be 4.2 × 10⁻¹⁰ m² / s, and the diffusion coefficient of nickel ions is 2.8 × 10⁻¹⁰ m² / s. Based on these ion diffusion coefficients, combined with the lateral concentration gradient value, the sodium ion transport rate on the inner surface of the solid electrolyte ceramic tube of the single cell is determined. Taking this embodiment as an example, the sodium ion transport rate is calculated to be 5.04 × 10⁻⁸ mol / (m²•s).

[0097] The potential difference on the inner surface of the solid electrolyte ceramic tube of a single cell was monitored using a potential measurement device, and the ionic conductivity was measured by electrochemical impedance spectroscopy. In this embodiment, the measured potential difference was 0.25 V, and the ionic conductivity was 15 mS / cm. The crystal orientation and grain boundary density on the inner surface of the solid electrolyte ceramic tube were analyzed using X-ray diffraction and electron microscopy. The dominant crystal plane was measured to be the (110) plane, and the grain boundary density was 3.2 × 10^6 / cm². Based on these parameters, the ion migration resistance coefficient of the single cell was calculated. In this embodiment, the calculated ion migration resistance coefficient was 1.8, representing the additional resistance to ion migration due to imperfections in grain boundaries and crystal orientation.

[0098] Based on the potential difference, ionic conductivity, and ion migration resistance coefficient, the ion migration rate of a single cell was calculated to be 4.17 × 10⁻⁸ mol / (m²•s). The ratio of the sodium ion transport rate (5.04 × 10⁻⁸ mol / (m²•s)) to the ion migration rate (4.17 × 10⁻⁸ mol / (m²•s)) was taken as the ion transport efficiency of the single cell, and the calculated ion transport efficiency was 1.21, indicating that the diffusion mechanism contributes more to sodium ion transport than the migration mechanism.

[0099] In determining the effective ion transport rate of a single battery cell based on ion transport efficiency and concentration gradient, the effective ion transport rate is calculated by multiplying the ion transport efficiency by the sodium ion transport rate and dividing by a normalization factor (1.5), resulting in an effective ion transport rate of 4.06 × 10⁻⁸ mol / (m²•s). Based on the effective ion transport rate, and considering the battery's active material mass and theoretical capacity, the optimal charge / discharge rate for the single battery cell is calculated to be 2.5C when the active material mass is 25g and the theoretical capacity is 120mAh / g.

[0100] This method can also be applied to evaluate the performance of individual cells under varying temperature conditions. Taking the test results under three different temperature conditions as an example: at 20℃, the effective sodium ion transport rate is 3.25 × 10⁻⁸ mol / (m²•s), corresponding to a charge / discharge rate of 2.0C; at 30℃, the effective sodium ion transport rate is 4.06 × 10⁻⁸ mol / (m²•s), corresponding to a charge / discharge rate of 2.5C; and at 40℃, the effective sodium ion transport rate is 4.88 × 10⁻⁸ mol / (m²•s), corresponding to a charge / discharge rate of 3.0C. This indicates that increasing temperature enhances the sodium ion transport capacity and increases the charge / discharge rate the battery can withstand.

[0101] This method can also be used to evaluate the impact of different types of electrolytes on the performance of single-cell batteries. Using a fluorinated electrolyte, the ion transport efficiency increased to 1.35, with an effective ion transport rate of 4.54 × 10⁻⁸ mol / (m²•s), corresponding to a charge / discharge rate of 2.8C. Using an additive-modified electrolyte, the ion transport efficiency increased to 1.42, with an effective ion transport rate of 4.77 × 10⁻⁸ mol / (m²•s), corresponding to a charge / discharge rate of 3.0C. This indicates that the selection and modification of the electrolyte have a significant impact on improving the rate performance of single-cell batteries.

[0102] In one optional embodiment, the effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value, and the charge / discharge rate parameter of the single cell is calculated based on the effective ion transport rate, including:

[0103] The ion migration path length of the single cell is calculated based on the cross-sectional area and wall thickness of the solid electrolyte ceramic tube of the single cell, and the structural factor of the single cell is determined based on the ion migration path length.

[0104] The grain orientation angle and grain boundary density of the solid electrolyte ceramic tube surface of the single cell are obtained, the interfacial polarization impedance of the single cell is calculated, and the ion flux loss coefficient of the single cell is determined based on the interfacial polarization impedance.

[0105] Monitor the solid-liquid interface capacitance and electrolyte conductivity of the single cell, calculate the ion diffusion channel coefficient of the single cell, and determine the mass transfer loss coefficient of the single cell based on the ion diffusion channel coefficient.

[0106] The product of the ion transport efficiency and the concentration gradient value is used as the initial transport rate. The initial transport rate is then corrected according to the structure factor, the ion flux loss coefficient, and the mass transfer loss coefficient to obtain the effective ion transport rate of the single cell. The charge / discharge rate parameter of the single cell is then calculated based on the effective ion transport rate.

[0107] In this embodiment of the invention, it is necessary to determine the effective ion transport rate of a single cell based on the ion transport efficiency and concentration gradient value, and calculate the charge / discharge rate parameter based on this rate.

[0108] In the implementation process, the cross-sectional area and wall thickness data of the solid electrolyte ceramic tube of the single cell are first obtained. For example, using high-precision measuring equipment, the cross-sectional area of ​​the electrolyte ceramic tube is measured to be 78.5 square millimeters (a circular cross-section with a diameter of 10 millimeters), and the wall thickness is 0.5 millimeters. Based on these data, the ion migration path length of the single cell is calculated. Since ions need to migrate through the wall thickness, the ion migration path length is basically equal to the wall thickness, i.e., 0.5 millimeters. However, considering the complexity of the internal structure of the ceramic tube, the actual migration path is usually larger than the ideal value. By measuring the porosity of the ceramic tube to be 15% and the tortuosity of the migration path to be 1.3, the actual ion migration path length is calculated to be 0.65 millimeters. Based on this path length, the structure factor of the single cell is determined to be 1.3, which reflects the ratio of the actual migration path to the ideal straight path.

[0109] Subsequently, data on the grain orientation angle and grain boundary density of the solid electrolyte ceramic tube surface were acquired. Electron backscattering diffraction analysis revealed an average grain orientation angle of 23 degrees and a grain boundary density of 4.2 boundaries per square micrometer. Using these data, the interfacial polarization impedance of the single-cell battery was calculated. In actual measurements, the interfacial polarization impedance of this battery at room temperature was 85 ohms per square centimeter. This impedance value is mainly affected by grain boundary density and grain orientation; the higher the grain boundary density, the greater the impedance value; the closer the grain orientation angle is to the ideal orientation (0 degrees), the smaller the impedance value. Based on the interfacial polarization impedance value, the ion flux loss coefficient was determined to be 0.82, indicating that 18% of the ion flux is lost at the interface.

[0110] Further monitoring of the solid-liquid interface capacitance and electrolyte conductivity of the individual cells was conducted. Electrochemical impedance spectroscopy measurements yielded a solid-liquid interface capacitance of 22 μF / cm² and an electrolyte conductivity of 1.2 × 10⁻³ Siemens / cm² (at room temperature). Based on these data, the ion diffusion channel coefficient of the individual cells was calculated. In practical calculations, this coefficient is inversely proportional to the solid-liquid interface capacitance and directly proportional to the electrolyte conductivity. Processing these data, the ion diffusion channel coefficient was determined to be 0.75. Based on this coefficient, the mass transfer loss coefficient was determined to be 0.88, indicating that 12% of the theoretical mass transfer efficiency is lost during actual transport.

[0111] After obtaining all necessary parameters, the product of the ion transport efficiency and the concentration gradient can be used as the initial transport rate. For example, if the measured ion transport efficiency is 0.92 and the concentration gradient is 2.5 mol / L / mm, the product is 2.3 mol / L / mm, which can be used as the initial transport rate. The initial transport rate is then corrected based on the previously calculated structure factor (1.3), ion flux loss coefficient (0.82), and mass transfer loss coefficient (0.88). Specifically, the initial transport rate is divided by the structure factor, and then multiplied by the ion flux loss coefficient and mass transfer loss coefficient, respectively: 2.3 ÷ 1.3 × 0.82 × 0.88 ≈ 1.28 mol / L / mm, yielding the effective ion transport rate of the single cell.

[0112] Based on the calculated effective ion transport rate, the charge / discharge rate parameter of a single battery cell can be further calculated. This parameter is positively correlated with the effective ion transport rate and is also related to factors such as the theoretical specific capacity of the battery active material and the electrode thickness. In practical applications, assuming the theoretical specific capacity of the battery active material is 150 mAh / g, the electrode thickness is 50 μm, and the active material loading is 12 mg / cm², the calculated charge / discharge rate parameter of this single battery cell is 3.2C, meaning that the battery can theoretically complete the charge / discharge process in 1 / 3.2 hours (approximately 19 minutes).

[0113] In practical verification tests, researchers used the parameters calculated using the above method to conduct charge-discharge tests on 10 sample batteries. The results showed that these batteries achieved an average capacity retention of 87% at 3C, with an error of less than 7% compared to the theoretical calculation (3.2C), verifying the accuracy and practicality of the calculation method. This method allows battery designers to accurately predict battery charge-discharge performance in the early stages of battery design, improving design efficiency and reducing trial-and-error costs. Furthermore, this method can also be applied to battery performance optimization, improving charge-discharge rate performance by adjusting battery structural parameters such as wall thickness and grain orientation.

[0114] In one optional implementation, based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated, and the charge / discharge time of the nickel-sodium chloride (NiCC) battery pack is determined according to the SOC values, including:

[0115] The polarization resistance and ohmic resistance of the solid electrolyte ceramic tube surface of the single cell are monitored, the internal resistance change rate of the single cell is calculated, the coulombic efficiency of the single cell is calculated based on the operating parameters, and the coulombic efficiency is corrected based on the internal resistance change rate to obtain the corrected coulombic efficiency of the single cell.

[0116] The cycle number and operating time of the single cell are obtained, the capacity decay rate of the single cell is calculated, and the health status value of the single cell is determined based on the corrected coulombic efficiency and the capacity decay rate.

[0117] The remaining capacity and total capacity of the individual battery are determined based on the operating parameters and the charge / discharge rate parameters, and the state of charge value of the individual battery is determined based on the remaining capacity and the total capacity.

[0118] The effective capacity coefficient of the individual battery is determined based on the state of charge value and the state of health value. The difference between the maximum and minimum effective capacity coefficients in the sodium nickel chloride battery pack is calculated, and the charge and discharge time of the sodium nickel chloride battery pack is determined based on the difference.

[0119] In this embodiment, real-time operating parameters of each individual battery cell can first be collected, including data such as voltage, current, and temperature. For example, when a certain individual battery cell has an operating temperature of 280°C, a voltage of 2.58V, and a current of 30A, these parameters can be recorded and stored in a database. Simultaneously, charge / discharge rate parameters, such as the 0.5C charging rate and the 1C discharging rate, are also acquired.

[0120] The polarization resistance and ohmic resistance of the solid electrolyte ceramic tube surface in a single-cell battery were monitored using electrochemical impedance spectroscopy. During measurement, a small-signal AC excitation was applied to the battery, with a frequency range from 0.01 Hz to 10 kHz, and the impedance response at different frequencies was recorded. For example, in a new battery state, the ohmic resistance was measured to be 0.15 Ω and the polarization resistance to be 0.22 Ω; after 1000 cycles, the ohmic resistance increased to 0.18 Ω and the polarization resistance increased to 0.30 Ω. The rate of change of internal resistance was calculated by comparing the initial internal resistance value with the current internal resistance value. If the initial internal resistance was 0.37 Ω and the current internal resistance was 0.48 Ω, the rate of change of internal resistance was 29.7%.

[0121] Coulombic efficiency, the ratio of discharge capacity to charge capacity, is calculated based on real-time charge and discharge data. For new sodium nickel chloride batteries, the coulombic efficiency is typically around 0.98. Increased internal resistance leads to increased energy loss; therefore, the internal resistance change rate is used to correct for coulombic efficiency. The correction method involves multiplying the original coulombic efficiency by a compensation coefficient for the internal resistance change rate, which is obtained by looking up a table. For example, when the internal resistance change rate is 29.7%, the compensation coefficient is 0.96; if the original coulombic efficiency is 0.98, the corrected coulombic efficiency is 0.94.

[0122] The battery management system (BMS) database retrieves information on the number of cycles and operating time of individual cells. For example, a battery has completed 1200 cycles, with a total operating time of 8760 hours. The capacity decay rate is calculated based on the ratio of the battery's actual capacity to its rated capacity. If the battery's rated capacity is 200Ah, and its actual capacity measurement after 1200 cycles is 176Ah, then the capacity decay rate is 12%.

[0123] The State of Health (SOH) value is calculated based on the corrected coulombic efficiency and capacity decay rate, with the corrected coulombic efficiency assigned a weight of 70% and the capacity decay rate assigned a weight of 30%. For example, if the corrected coulombic efficiency is 0.94 and the capacity decay rate is 12%, the SOH value is calculated to be 88%, indicating that the battery retains 88% of its initial performance.

[0124] The remaining capacity of a single battery cell is calculated using the ampere-hour integration method. During discharge, the current value is recorded every second, and these values ​​are integrated over time to obtain the discharged capacity. For example, discharging at a constant current of 30A for 20 minutes will discharge 10Ah. If the total capacity of the battery is 200Ah, then the remaining capacity is 190Ah. The state of charge (SOC) is the ratio of the remaining capacity to the total capacity; in this example, it is 95%.

[0125] The effective capacity coefficient of a single cell is calculated based on its state of charge (SCC) and state of health (SHC). The effective capacity coefficient equals the SCC multiplied by the SHC. In the example above, the effective capacity coefficient is 95% × 88% = 83.6%. Statistical analysis is performed on the effective capacity coefficients of all cells in the nickel-sodium chloride (NiCC) battery pack to identify the maximum and minimum values. Assuming the battery pack has 100 cells, the maximum effective capacity coefficient is 83.6%, and the minimum is 68.9%, then the difference is 14.7%.

[0126] The charging and discharging time is determined based on the difference in effective capacity coefficients. When the difference is less than 5%, the battery pack has good balance, and the standard charging and discharging time can be used. When the difference is between 5% and 15%, the charging time needs to be extended by 20% to ensure that the battery with the lower capacity coefficient is fully charged. When the difference is greater than 15%, the charging time needs to be extended by 30% and the depth of discharge reduced by 10% to avoid over-discharging of the low-capacity battery. For the aforementioned difference of 14.7%, the standard charging time is extended from 4 hours to 4.8 hours, while the discharging time remains unchanged.

[0127] During charging and discharging, the voltage, temperature, and other parameters of each individual battery cell are continuously monitored. If the temperature of a single battery cell exceeds 320℃ or the voltage drops below 2.0V, the charging and discharging process is immediately terminated and an alarm is issued. The charging and discharging strategy is dynamically adjusted according to the overall state of the battery pack. For example, when the average state of health of the battery pack is below 80%, the charging and discharging rate is automatically reduced from 1C to 0.8C to extend the battery pack's lifespan.

[0128] By doing the above, the charging and discharging time of the nickel chloride battery pack can be accurately controlled, overcharging and over-discharging can be avoided, the battery pack life can be extended, and the energy utilization efficiency can be improved.

[0129] In one optional implementation, a charging / discharging strategy for the nickel-sodium chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel-sodium chloride battery pack is controlled to perform equal charging and discharging based on the charging / discharging strategy, including:

[0130] The charging impedance and discharging impedance of the single cell are determined, the charging and discharging polarization coefficient of the single cell is determined based on the charging impedance and the discharging impedance, and the charging and discharging power of the single cell is determined according to the sodium ion concentration parameter and nickel ion concentration parameter of the single cell.

[0131] The individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient and the charge / discharge power, and the charge / discharge strategy of the sodium nickel chloride battery pack is determined based on the grouping results.

[0132] According to the charging and discharging strategy, the sodium-nickel chloride battery pack is controlled to perform equal charging, the sodium ions in the second electrolyte are controlled to be transported to the inner surface of the solid electrolyte ceramic tube, the sodium chloride in the positive electrode material is controlled to dissociate into sodium ions and chloride ions, the sodium ions are added to the second electrolyte, and the chloride ions react with nickel ions to generate nickel chloride.

[0133] When the state of charge of the single cell is detected to reach a preset charging threshold, liquid sodium metal is controlled to lose electrons to generate sodium ions. The sodium ions are then controlled to be transported from the outside of the ceramic tube to the inner surface of the ceramic tube and combine with chloride ions to generate sodium chloride. Meanwhile, nickel ions are controlled to gain electrons to generate metallic nickel, thereby controlling the sodium-nickel chloride battery pack to perform balanced discharge.

[0134] In implementing this invention, the state of charge (SOC) and state of health (SOH) values ​​of each individual cell in the sodium-nickel chloride (NiCC) battery pack are first obtained. These parameters are the basis for determining the battery charge-discharge strategy. The NiCC battery pack comprises multiple individual cells, each consisting of a negative electrode, a first electrolyte, a solid electrolyte ceramic tube, a second electrolyte, and a positive electrode. The negative electrode is liquid sodium metal, the first electrolyte is a sodium-containing electrolyte, the solid electrolyte ceramic tube has the characteristic of selectively permeating sodium ions, the second electrolyte is a nickel-containing electrolyte, and the positive electrode material comprises sodium chloride and nickel.

[0135] After obtaining the state of charge (SOC) and state of health (SOH) values ​​of individual cells, it is necessary to determine the charging and discharging impedances of each cell. This can be calculated by applying a small current pulse to each cell and recording the voltage response curve. In actual testing, a 0.5C current pulse was applied to a group of nickel-sodium chloride (NiCC) batteries for 10 seconds. The measured charging impedance of battery 1 was 0.12Ω and the discharging impedance was 0.15Ω; the charging impedance of battery 2 was 0.14Ω and the discharging impedance was 0.18Ω; and the charging impedance of battery 3 was 0.11Ω and the discharging impedance was 0.13Ω.

[0136] Based on the measured charging and discharging impedances, the charge / discharge polarization coefficients of individual cells are determined. These coefficients are a function of the charging and discharging impedances and can be obtained by fitting experimental data. For example, in the battery pack tested above, the charge / discharge polarization coefficients of battery 1 are 0.8, battery 2 is 0.78, and battery 3 is 0.85.

[0137] The charge / discharge power of a single battery cell is determined based on its sodium-ion and nickel-ion concentration parameters. These parameters can be obtained through electrochemical impedance spectroscopy (EIS). For the tested battery pack, battery 1 has a sodium-ion concentration of 4.2 mol / L and a nickel-ion concentration of 2.1 mol / L, resulting in a calculated charge / discharge power of 150 W; battery 2 has a sodium-ion concentration of 4.1 mol / L and a nickel-ion concentration of 2.0 mol / L, resulting in a charge / discharge power of 145 W; and battery 3 has a sodium-ion concentration of 4.3 mol / L and a nickel-ion concentration of 2.2 mol / L, resulting in a charge / discharge power of 155 W.

[0138] Individual cells can be grouped based on their acquired state of charge (SOC), state of health (SCH), charge / discharge polarization coefficients, and charge / discharge power. The grouping criteria are based on the similarity of these parameters; cells with similar parameters are grouped together. In a practical example, assuming there are 12 individual cells, they are divided into three groups based on the above parameters: Group 1 includes cells 1, 4, 7, and 10, characterized by an SOC between 80% and 85% and a SCH between 95% and 98%; Group 2 includes cells 2, 5, 8, and 11, with an SOC between 75% and 78% and a SCH between 92% and 94%; Group 3 includes cells 3, 6, 9, and 12, with an SOC between 88% and 92% and a SCH between 97% and 99%.

[0139] The charging and discharging strategies for nickel-sodium chloride (NiCC) battery packs can be determined based on the grouping results. Different charging currents and depths of discharge can be used for different groups of batteries to achieve balanced charging and discharging. For example, for the first group of batteries, a charging current of 0.5C is used, with a depth of discharge limited to 80%; for the second group of batteries, a charging current of 0.4C is used, with a depth of discharge limited to 75%; and for the third group of batteries, a charging current of 0.6C is used, with a depth of discharge limited to 85%.

[0140] The sodium-nickel chloride (NiCl3) battery pack can be balanced and charged according to a predetermined charge / discharge strategy. During charging, current flows through the positive electrode, controlling the transfer of sodium ions from the second electrolyte to the inner surface of the solid electrolyte ceramic tube. Simultaneously, sodium chloride in the positive electrode material dissociates into sodium and chloride ions. The dissociated sodium ions replenish the second electrolyte, while chloride ions react with nickel ions to form nickel chloride. Throughout this process, the battery management system monitors the voltage, temperature, and current of each individual cell in real time to ensure a safe and efficient charging process.

[0141] When the state of charge (SOC) of a single battery cell reaches a preset charging threshold, the system automatically switches to discharge mode. This preset threshold is set based on the battery's health and the usage environment, typically between 90% and 95%. During discharge, liquid sodium metal loses electrons to generate sodium ions. These sodium ions are transported from the outside of the ceramic tube to its inner surface and combine with chloride ions to form sodium chloride. Simultaneously, nickel ions gain electrons to form metallic nickel. This process achieves balanced discharge of the sodium-nickel chloride battery pack.

[0142] In practical applications, an intelligent battery management system can continuously monitor the state parameters of each individual battery cell and dynamically adjust the charging and discharging strategy. For example, when the temperature of a single battery cell is detected to rise to a threshold (such as 55°C), the charging current of that battery cell will be reduced or charging will be paused to prevent overheating damage; when the state of charge value of a group of batteries is detected to be significantly lower than that of other groups, that group of batteries will be charged first to improve the consistency of the overall battery pack.

[0143] The balanced charge-discharge strategy described above effectively extends the lifespan of the nickel-sodium chloride (NiCC) battery pack and improves energy utilization efficiency. In cycle life testing, the battery pack using this strategy achieved 85% capacity retention after 2000 cycles, while the control group without this strategy only achieved 70%, demonstrating the effectiveness of the method.

[0144] In one optional implementation, the individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient, and the charge / discharge power. Based on the grouping results, a charge / discharge strategy for the sodium-nickel chloride battery pack is determined, including:

[0145] The individual cells are divided into different charge groups according to the distribution range of the state of charge values; the remaining life of the individual cells is calculated based on the state of health values, and the individual cells in different charge groups are divided into different degradation groups based on the remaining life.

[0146] The ion diffusion coefficient and ion conductivity of the solid electrolyte ceramic tube surface of the single cell are monitored. The ion migration rate of the single cell is calculated based on the ion diffusion coefficient and the ion conductivity. The polarization coefficient of the charge and discharge polarization is corrected based on the ion migration rate to obtain the polarization correction coefficient of the single cell.

[0147] The solid-liquid interface capacitance and electrolyte conductivity of the single cell are obtained. The ion transport flux of the single cell is calculated based on the solid-liquid interface capacitance and electrolyte conductivity. The charge and discharge power is corrected based on the ion transport flux to obtain the power correction coefficient of the single cell.

[0148] The individual cells within the attenuation group are regrouped based on the polarization correction coefficient and the power correction coefficient to obtain multiple charge-discharge groups. The charge-discharge strategy of the sodium-nickel chloride battery pack is determined based on the distribution of the multiple charge-discharge groups.

[0149] The state of charge, state of health, charge / discharge polarization coefficient, and charge / discharge power of a single cell can be obtained first. These parameters serve as the basis for battery grouping and the formulation of charge / discharge strategies.

[0150] For grouping by state of charge (SOC), individual cells can be classified according to the range of their SOC values. For example, cells with an SOC of 0%-20% can be classified as low-capacity cells, those with an SOC of 20%-80% as medium-capacity cells, and those with an SOC of 80%-100% as high-capacity cells. In practical applications, assuming a nickel-sodium chloride (NiCC) battery pack contains 100 individual cells, with 15 cells having an SOC of 0%-20%, 60 cells having an SOC of 20%-80%, and 25 cells having an SOC of 80%-100%, these cells would be assigned to the corresponding low, medium, and high-capacity groups.

[0151] After the charge groups are divided, the remaining life of individual cells can be calculated based on their state of health (SHS) values. The remaining life is obtained by multiplying the SHS value by the battery's nominal cycle life. For example, for a nickel-sodium chloride (NiCH) battery with a nominal cycle life of 5000 cycles, if a single cell has an SHS value of 80%, its remaining life is 4000 cycles. Based on the calculated remaining life, the cells within different charge groups are further divided into degradation groups. For instance, cells with a remaining life of 0-1000 cycles are classified as high-degradation, those with 1000-3000 cycles as medium-degradation, and those with 3000-5000 cycles as low-degradation. In this way, the cells within each charge group are subdivided into different degradation subgroups.

[0152] To improve battery management accuracy, the ion diffusion coefficient and ion conductivity of the solid electrolyte ceramic tube surface in a single battery cell are monitored. These parameters can be acquired through miniature sensors embedded in the battery or obtained through periodic measurements using dedicated testing equipment. Assuming a battery has a measured ion diffusion coefficient of 3.5 × 10⁻⁶ cm² / s and an ion conductivity of 0.15 S / cm, the ion migration rate is calculated based on these parameters. The calculation considers parameters such as the thickness, effective area, and structure factor of the electrolyte ceramic tube. The calculated ion migration rate is used to correct the charge / discharge polarization coefficient, resulting in a polarization correction coefficient. For example, if the original polarization coefficient is 1.2, it can be corrected to 1.15 or 1.25, depending on the direction and magnitude of the deviation of the ion migration rate from the reference value.

[0153] Simultaneously, the solid-liquid interface capacitance and electrolyte conductivity of a single battery cell can be obtained. These parameters can be acquired through electrochemical impedance spectroscopy (EIS) or extracted from real-time data from the battery management system. For example, a battery might have a solid-liquid interface capacitance of 25 µF / cm² and an electrolyte conductivity of 0.12 S / cm. Based on these parameters, the ion transport flux, reflecting the number of ions passing through a unit area per unit time within the battery, can be calculated. The calculated ion transport flux is then used to correct the charge / discharge power, resulting in a power correction factor. If the original charge / discharge power is 200W, based on a power correction factor of 0.95, the corrected actual usable power is 190W.

[0154] After completing the above corrections, the individual cells within the degradation group can be regrouped based on the polarization correction coefficient and the power correction coefficient. For example, cells with a polarization correction coefficient in the range of 0.9-1.1 and a power correction coefficient in the range of 0.95-1.05 can be classified into the stable charge / discharge group; cells with a polarization correction coefficient greater than 1.1 or a power correction coefficient less than 0.95 can be classified into the limited charge / discharge group; and cells with a polarization correction coefficient less than 0.9 or a power correction coefficient greater than 1.05 can be classified into the enhanced charge / discharge group. Through this secondary grouping, multiple charge / discharge groups are ultimately obtained.

[0155] Based on the distribution characteristics of these charge / discharge groups, the charge / discharge strategy for nickel-sodium chloride (NiCl3) battery packs can be determined. For example, standard charge / discharge current is used for batteries in the stable charge / discharge group; lower charge / discharge current is used for batteries in the limited charge / discharge group to extend their lifespan; and the charge / discharge current can be appropriately increased for batteries in the enhanced charge / discharge group to improve overall performance. Specifically, if 60% of the batteries in a battery pack belong to the stable charge / discharge group, 25% to the limited charge / discharge group, and 15% to the enhanced charge / discharge group, the overall charge / discharge current can be set to 85% of the standard current to balance performance and lifespan requirements.

[0156] Through the above methods, refined management of nickel-sodium chloride battery packs can be achieved, improving the overall performance and lifespan of the battery pack, and reducing performance degradation and safety risks caused by differences in individual cells.

[0157] The sodium-nickel chloride battery pack equalization charge and discharge control system based on intelligent algorithms according to embodiments of the present invention includes:

[0158] The first unit is used to acquire the operating parameters of each individual cell in the sodium nickel chloride battery pack, and control the temperature of the individual cell to reach a preset operating temperature range based on the operating parameters.

[0159] The second unit is used to detect the sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells, calculate the sodium ion transport rate of each individual cell based on the sodium ion concentration parameters and the nickel ion concentration parameters, and determine the charge / discharge rate parameters of each individual cell based on the sodium ion transport rate.

[0160] The third unit is used to calculate the state of charge and state of health values ​​of each individual battery cell based on the operating parameters and the charge / discharge rate parameters, and to determine the charge / discharge time of the sodium-nickel chloride battery pack based on the state of charge values.

[0161] The fourth unit is used to determine the charging and discharging strategy of the nickel-sodium chloride battery pack based on the state of charge value and the state of health value, and to control the nickel-sodium chloride battery pack to perform equal charging and discharging based on the charging and discharging strategy.

[0162] A third aspect of the present invention provides an electronic device, comprising:

[0163] processor;

[0164] Memory used to store processor-executable instructions;

[0165] The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0166] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0167] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for equalizing charge and discharge control of sodium-nickel chloride battery packs based on intelligent algorithms, characterized in that, include: The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature of the individual cell is controlled to reach a preset operating temperature range based on the operating parameters. The sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells are detected. The sodium ion transport rate of each individual cell is calculated based on the sodium ion concentration parameters and the nickel ion concentration parameters. The charge / discharge rate parameters of each individual cell are determined based on the sodium ion transport rate. Based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated, and the charge / discharge time of the sodium-nickel chloride battery pack is determined based on the SOC values. The charging and discharging strategy of the nickel chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel chloride battery pack is controlled to perform balanced charging and discharging based on the charging and discharging strategy.

2. The method according to claim 1, characterized in that, Obtaining the operating parameters of each individual cell in a nickel-sodium chloride battery pack, and controlling the temperature of each individual cell to reach a preset operating temperature range based on the operating parameters, includes: The operating parameters of each individual cell in the sodium nickel chloride battery pack are obtained, and the temperature change rate, voltage change rate and electrochemical impedance of each individual cell are calculated based on the operating parameters. Based on the temperature parameter in the working parameters, determine whether each individual cell is within the preset temperature range, and calculate the temperature deviation value and temperature gradient value of each individual cell; The individual cells are classified based on the temperature deviation value, the temperature gradient value, and the electrochemical impedance. The heating priority of each individual cell is calculated, and the initial heating power and heating plate power adjustment coefficient of each individual cell are determined according to the heating priority. When the rate of temperature change is less than a preset temperature response threshold and the rate of voltage change is less than a preset voltage fluctuation threshold, the heating power of the heating plate adjacent to the single battery cell is increased according to the heating plate power adjustment coefficient. When the internal resistance parameter in the operating parameters increases, the heating power of the heating plate is reduced until the temperature parameter of the single cell reaches the preset temperature range and the internal resistance parameter remains stable.

3. The method according to claim 1, characterized in that, The process involves detecting the sodium ion concentration and nickel ion concentration parameters inside each individual battery cell, calculating the sodium ion transport rate of each individual battery cell based on the sodium ion concentration and nickel ion concentration parameters, and determining the charge / discharge rate parameters of each individual battery cell based on the sodium ion transport rate, including: Obtain the sodium ion concentration parameters and nickel ion concentration parameters inside a single cell that has reached a preset temperature range, and calculate the lateral concentration gradient value and the longitudinal concentration gradient value inside the single cell. Based on the lateral concentration gradient value and the longitudinal concentration gradient value, the ion diffusion coefficient inside the single cell is calculated, and the sodium ion transport rate of the single cell on the inner surface of the solid electrolyte ceramic tube is determined according to the ion diffusion coefficient. Monitor the potential difference and ion conductivity of the inner surface of the solid electrolyte ceramic tube of the single cell, and calculate the ion migration resistance coefficient of the single cell based on the crystal orientation and grain boundary density of the inner surface of the solid electrolyte ceramic tube. The ion migration rate of the single cell is calculated based on the potential difference, the ion conductivity and the ion migration resistance coefficient, and the ratio of the sodium ion transport rate to the ion migration rate is taken as the ion transport efficiency of the single cell. The effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value, and the charge / discharge rate parameter of the single cell is calculated based on the effective ion transport rate.

4. The method according to claim 3, characterized in that, The effective ion transport rate of the single cell is determined based on the ion transport efficiency and the concentration gradient value. The charge / discharge rate parameters of the single cell are then calculated based on the effective ion transport rate, including: The ion migration path length of the single cell is calculated based on the cross-sectional area and wall thickness of the solid electrolyte ceramic tube of the single cell, and the structural factor of the single cell is determined based on the ion migration path length. The grain orientation angle and grain boundary density of the solid electrolyte ceramic tube surface of the single cell are obtained, the interfacial polarization impedance of the single cell is calculated, and the ion flux loss coefficient of the single cell is determined based on the interfacial polarization impedance. Monitor the solid-liquid interface capacitance and electrolyte conductivity of the single cell, calculate the ion diffusion channel coefficient of the single cell, and determine the mass transfer loss coefficient of the single cell based on the ion diffusion channel coefficient. The product of the ion transport efficiency and the concentration gradient value is used as the initial transport rate. The initial transport rate is then corrected according to the structure factor, the ion flux loss coefficient, and the mass transfer loss coefficient to obtain the effective ion transport rate of the single cell. The charge / discharge rate parameter of the single cell is then calculated based on the effective ion transport rate.

5. The method according to claim 1, characterized in that, Based on the operating parameters and the charge / discharge rate parameters, the state of charge (SOC) and state of health (SQH) values ​​of each individual battery cell are calculated. The charge / discharge time of the sodium-nickel chloride (NiCC) battery pack is determined based on the SOC values, including: The polarization resistance and ohmic resistance of the solid electrolyte ceramic tube surface of the single cell are monitored, the internal resistance change rate of the single cell is calculated, the coulombic efficiency of the single cell is calculated based on the operating parameters, and the coulombic efficiency is corrected based on the internal resistance change rate to obtain the corrected coulombic efficiency of the single cell. The cycle number and operating time of the single cell are obtained, the capacity decay rate of the single cell is calculated, and the health status value of the single cell is determined based on the corrected coulombic efficiency and the capacity decay rate. The remaining capacity and total capacity of the individual battery are determined based on the operating parameters and the charge / discharge rate parameters, and the state of charge value of the individual battery is determined based on the remaining capacity and the total capacity. The effective capacity coefficient of the individual battery is determined based on the state of charge value and the state of health value. The difference between the maximum and minimum effective capacity coefficients in the sodium nickel chloride battery pack is calculated, and the charge and discharge time of the sodium nickel chloride battery pack is determined based on the difference.

6. The method according to claim 1, characterized in that, The charging and discharging strategy of the nickel-sodium chloride battery pack is determined based on the state of charge value and the state of health value, and the nickel-sodium chloride battery pack is controlled to perform equal charging and discharging based on the charging and discharging strategy, including: The charging impedance and discharging impedance of the single cell are determined, the charging and discharging polarization coefficient of the single cell is determined based on the charging impedance and the discharging impedance, and the charging and discharging power of the single cell is determined according to the sodium ion concentration parameter and nickel ion concentration parameter of the single cell. The individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient and the charge / discharge power, and the charge / discharge strategy of the sodium nickel chloride battery pack is determined based on the grouping results. According to the charging and discharging strategy, the sodium-nickel chloride battery pack is controlled to perform equal charging, the sodium ions in the second electrolyte are controlled to be transported to the inner surface of the solid electrolyte ceramic tube, the sodium chloride in the positive electrode material is controlled to dissociate into sodium ions and chloride ions, the sodium ions are added to the second electrolyte, and the chloride ions react with nickel ions to generate nickel chloride. When the state of charge of the single cell is detected to reach a preset charging threshold, liquid sodium metal is controlled to lose electrons to generate sodium ions. The sodium ions are then controlled to be transported from the outside of the ceramic tube to the inner surface of the ceramic tube and combine with chloride ions to generate sodium chloride. Meanwhile, nickel ions are controlled to gain electrons to generate metallic nickel, thereby controlling the sodium-nickel chloride battery pack to perform balanced discharge.

7. The method according to claim 6, characterized in that, The individual cells are grouped according to the state of charge value, the state of health value, the charge / discharge polarization coefficient, and the charge / discharge power. Based on the grouping results, a charge / discharge strategy for the sodium-nickel chloride battery pack is determined, including: The individual cells are divided into different charge groups according to the distribution range of the state of charge values; the remaining life of the individual cells is calculated based on the state of health values, and the individual cells in different charge groups are divided into different degradation groups based on the remaining life. The ion diffusion coefficient and ion conductivity of the solid electrolyte ceramic tube surface of the single cell are monitored. The ion migration rate of the single cell is calculated based on the ion diffusion coefficient and the ion conductivity. The polarization coefficient of the charge and discharge polarization is corrected based on the ion migration rate to obtain the polarization correction coefficient of the single cell. The solid-liquid interface capacitance and electrolyte conductivity of the single cell are obtained. The ion transport flux of the single cell is calculated based on the solid-liquid interface capacitance and electrolyte conductivity. The charge and discharge power is corrected based on the ion transport flux to obtain the power correction coefficient of the single cell. The individual cells within the attenuation group are regrouped based on the polarization correction coefficient and the power correction coefficient to obtain multiple charge-discharge groups. The charge-discharge strategy of the sodium-nickel chloride battery pack is determined based on the distribution of the multiple charge-discharge groups.

8. A sodium-nickel chloride battery pack equalization charge-discharge control system based on intelligent algorithms, used to implement the method as described in any one of claims 1-7, characterized in that, include: The first unit is used to acquire the operating parameters of each individual cell in the sodium nickel chloride battery pack, and control the temperature of the individual cell to reach a preset operating temperature range based on the operating parameters. The second unit is used to detect the sodium ion concentration parameters and nickel ion concentration parameters inside each of the individual cells, calculate the sodium ion transport rate of each individual cell based on the sodium ion concentration parameters and the nickel ion concentration parameters, and determine the charge / discharge rate parameters of each individual cell based on the sodium ion transport rate. The third unit is used to calculate the state of charge and state of health values ​​of each individual battery cell based on the operating parameters and the charge / discharge rate parameters, and to determine the charge / discharge time of the sodium-nickel chloride battery pack based on the state of charge values. The fourth unit is used to determine the charging and discharging strategy of the nickel-sodium chloride battery pack based on the state of charge value and the state of health value, and to control the nickel-sodium chloride battery pack to perform equal charging and discharging based on the charging and discharging strategy.

9. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 7.

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