Method for prolonging total cumulative service life of battery by means of reducing ambient temperature

Abstract

A method for prolonging the total cumulative service life of a battery by means of reducing an ambient temperature, the method comprising the following steps: setting ambient temperatures, and performing degradation tests on a battery, so as to acquire a degradation curve of an SOH index of the battery along with a cumulative usage amount at different ambient temperatures; on the basis of the real-time impact of the ambient temperature on the SOH index, acquiring temperature drop SOH loss amounts caused by different temperature drop amplitudes; on the basis of the long-term impact of the ambient temperature on the degradation curve, acquiring temperature drop service life gain amounts caused by different temperature drop amplitudes; weighing the negative impacts of the temperature drop amplitudes on the SOH index and the positive impacts of the temperature drop amplitudes on the total cumulative service life, so as to calculate an optimal ambient temperature; and dynamically adjusting the ambient temperature where the battery is located, such that the body temperature of the battery is within ±2°C of the optimal ambient temperature. By means of selecting the optimal ambient temperature for the battery, the single-cycle endurance performance is not seriously affected, and the total cumulative service life of the battery can be doubled, thereby significantly reducing the swapping and maintenance costs of the battery.

Description

A method to extend the total cumulative lifespan of a battery by reducing ambient temperature Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for extending the total cumulative lifespan of a battery by reducing the ambient temperature. Background Technology

[0002] With the development of new energy technologies and industries, batteries are widely used in various fields and industries, and their reliable operation is crucial for the normal use of equipment. However, it is generally accepted that low-temperature operating environments will adversely affect the performance of lithium batteries, so lithium batteries are often avoided in low-temperature environments. Technical issues

[0003] As is well known, lithium iron phosphate batteries have poor low-temperature performance. At low temperatures, battery activity decreases, lithium insertion and extraction capabilities decline, and usable capacity is reduced. For example, a certain battery retains 100% capacity at 25°C, approximately 80% at 0°C, and only about 55% at -20°C. Ambient temperature has a significant impact on battery usability. To ensure the normal operation of the devices powered by the battery, the operating temperature is generally maintained at around 20-25°C. In low-temperature environments, measures such as thermal insulation of the battery compartment and the installation of heaters are typically used to ensure the safe and efficient operation of energy storage devices.

[0004] Generally, the industry widely believes that low-temperature environments are detrimental to battery operation. For example, adding a battery preheating system to new energy electric vehicles ensures that the battery maintains its normal operating temperature, preventing significant capacity degradation and thus ensuring normal operation. However, the inventors have found through experiments that this method does not extend the cumulative lifespan of the battery and increases the frequency of battery replacement and maintenance costs. Technical solutions

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for extending the total cumulative lifespan of a battery by reducing the ambient temperature, thereby solving the problem that in the prior art, batteries at normal operating temperatures are not conducive to extending the cumulative lifespan of the battery, and also increase the frequency of battery replacement and maintenance costs.

[0006] To achieve the above and other related objectives, the present invention provides a method for extending the total cumulative lifespan of a battery by reducing the ambient temperature, comprising:

[0007] Obtain the degradation curve, set the ambient temperature, conduct a degradation test on the battery, and obtain the degradation curve of the battery SOH index with the cumulative usage under different ambient temperatures;

[0008] The SOH loss due to temperature drop is obtained. Based on the real-time effect of ambient temperature on the SOH index, the SOH loss due to temperature drop caused by different temperature drop amplitudes is obtained.

[0009] Obtain the temperature drop lifetime gain; based on the long-term influence of the ambient temperature on the degradation curve, obtain the temperature drop lifetime gain caused by different temperature drop amplitudes.

[0010] The optimal ambient temperature is calculated by weighing the negative impact of the temperature drop on the SOH index and the positive impact of the temperature drop on the total cumulative lifetime through the SOH loss and the lifetime gain.

[0011] Adjust the battery's internal temperature and dynamically adjust the ambient temperature to keep the battery's internal temperature within ±2℃ of the optimal ambient temperature.

[0012] Optionally, when weighing the negative impact of the temperature drop on the SOH index and the positive impact of the temperature drop on the total cumulative lifespan, a weighting coefficient A is set and multiplied by the SOH loss due to temperature drop, and a weighting coefficient B is set and multiplied by the lifespan gain due to temperature drop. The two products are then added together to obtain a comprehensive weighting index. Adjusting the ambient temperature of the battery can change the temperature drop, thereby affecting the value of the comprehensive weighting index. When the value of the comprehensive weighting index is at its maximum, the ambient temperature is the optimal ambient temperature. The weighting coefficients A and B are preset or obtained after training a mathematical model, and their values ​​can be positive or negative.

[0013] Optionally, the total cumulative lifespan is calculated as the cumulative usage from the time the battery is put into use until the SOH index reaches the failure threshold; the failure threshold is a certain value in the range of the battery's SOH index, and when the SOH index reaches the failure threshold, the battery can no longer work stably.

[0014] Optionally, the SOH index includes one or more of the following: actual maximum energy storage capacity, actual maximum energy storage capacity attenuation, actual maximum power storage capacity, actual maximum power storage capacity attenuation, relative energy storage capacity, relative energy storage capacity attenuation, relative power storage capacity attenuation, actual internal resistance, actual internal resistance attenuation, single actual discharge duration, single actual discharge duration attenuation, relative discharge duration, single actual charging duration, single actual charging duration attenuation, relative charging duration, actual work done by the battery's actual maximum energy storage capacity for the operation of power-consuming equipment, and mileage generated by the battery's actual maximum energy storage capacity for vehicle driving.

[0015] Optionally, the cumulative usage is the cumulative result of the actual usage measurement of the battery. The method for calculating the cumulative usage at a specific time is the cumulative result of the actual usage measurement generated within the time range from when the battery is put into use to the specific time.

[0016] Optionally, the types of cumulative usage include one or more of the following: cumulative charging amount, cumulative discharging amount, cumulative absolute value charging and discharging amount, cumulative charging time, cumulative discharging time, cumulative charging and discharging time, cumulative idle time, cumulative charging times, cumulative discharging times, cumulative charging and discharging times, cumulative idle times, calendar service time, cumulative result of actual workload generated by the operation of battery-powered equipment, cumulative result of actual work done by the operation of battery-powered equipment, and cumulative result of actual mileage generated by battery-powered vehicle driving.

[0017] Optionally, the method for calculating the SOH loss due to temperature drop is as follows: for a battery with a specific cumulative usage, the SOH index value corresponding to the battery body temperature at a certain temperature T1 is represented by R1, and the SOH index value corresponding to the battery body temperature at another temperature T2 is represented by R2. The difference between R1 and R2 is the SOH loss due to temperature drop, where the value of T2 is lower than the value of T1.

[0018] Optionally, the method for calculating the temperature drop lifetime gain is as follows: for a battery with a specific cumulative usage, the total cumulative lifetime expected to operate when the battery body temperature is at a certain temperature T1 is represented by L1, and the total cumulative lifetime expected to operate when the battery body temperature is at a certain temperature T2 is represented by L2. The difference between L1 and L2 is the temperature drop lifetime gain.

[0019] Optionally, the ambient temperature is ±0.5℃ of at least one integer temperature between -50℃ and 50℃, and the values ​​of T1, T2, and the optimal ambient temperature are ±0.5℃ of at least one integer temperature between -50℃ and 50℃. The upper and lower limits of the range of values ​​for T1, T2, and the optimal ambient temperature are consistent with the upper and lower limits of the range of values ​​for the ambient temperature.

[0020] Optionally, the upper limit of the ambient temperature range is one of the following: 50℃, 45℃, 40℃, 35℃, 30℃, 25℃, 22.5℃, 20℃, 17.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, and -15℃; the lower limit of the ambient temperature range is 30℃, 25℃, 22.5℃, and 20℃. One of the following: 17.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, -15℃, -17.5℃, -20℃, -22.5℃, -25℃, -27.5℃, -30℃, -32.5℃, -35℃, -37.5℃, -40℃, -42.5℃, -45℃, -47.5℃, -50℃. Beneficial effects

[0021] In the aforementioned method of extending the total cumulative lifespan of batteries by lowering ambient temperature, the inventors, through extensive experimental research, discovered that the cumulative usage of batteries can accurately describe the performance degradation process of lithium batteries under random and complex scenarios. The total cumulative lifespan can highly homogenize the significantly different performance degradation processes of lithium batteries under various complex and random scenarios. Simultaneously, the inventors also found that although placing lithium modules in a low-temperature environment leads to a sharp decrease in lithium battery capacity, the low-temperature environment does not cause permanent damage to the lithium battery capacity. On the contrary, the low-temperature environment can significantly extend the total cumulative lifespan of lithium batteries, including cumulative charging capacity and cumulative discharging capacity. Furthermore, the capacity of lithium batteries recovers rapidly when the ambient temperature returns to room temperature. This indicates that a low-temperature environment can be considered a beneficial factor; actively creating a low-temperature environment helps extend the total cumulative lifespan of lithium batteries, and is particularly suitable for energy storage scenarios where lithium battery capacity requirements are not high, but cumulative charging capacity requirements are high.

[0022] In summary, while low temperatures negatively impact battery capacity, this effect is not permanent. On the contrary, low temperatures significantly extend the battery's total lifespan; that is, by adjusting the ambient temperature, battery life can be increased. Specifically, by balancing the negative impact of temperature reduction on the State of Harm (SOH) index with its positive impact on the battery's total lifespan, an optimal ambient temperature can be selected for the battery. At this optimal temperature, the basic single-charge range performance is not severely affected, while the total lifespan of the battery is doubled, thereby significantly reducing battery replacement and maintenance costs. Attached Figure Description

[0023] Figure 1 is a flowchart of a method for extending the total cumulative lifespan of a battery by reducing the ambient temperature in an embodiment of the present invention.

[0024] Figure 2 shows the degradation curves of the SOH index of a single battery with cumulative usage at the reference operating temperature and in a low-temperature environment.

[0025] Figure 3 is a scatter plot of the battery SOH index as a function of cumulative usage under temperature disturbance at the baseline operating temperature within a certain cumulative usage range.

[0026] Figure 4 shows the degradation curves of the SOH index of the battery with cumulative usage for two batteries connected in series and a single battery under the reference operating temperature and low temperature environment. Embodiments of the present invention

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0029] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0030] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0031] In an exemplary embodiment, as shown in FIG1, a method for extending the total cumulative lifespan of a battery by reducing the ambient temperature includes at least steps S110 to S150, which are described in detail below:

[0032] Step S110: Obtain the degradation curve, set the ambient temperature, perform a degradation test on the battery, and obtain the degradation curve of the battery SOH index with the cumulative usage under different ambient temperatures.

[0033] As shown in Figure 2, the total cumulative lifespan of the battery at the reference operating temperature is much shorter than that of the battery at low temperature. Furthermore, the SOH index of the battery at low temperature is lower than that at the reference operating temperature, which is consistent with existing common knowledge.

[0034] The degradation curve describes the relationship between the State of Health (SOH) index and the cumulative usage during battery use. As the cumulative usage increases, the SOH index gradually decreases.

[0035] In some embodiments, the upper limit of the ambient temperature range includes one of the following: 50℃, 45℃, 40℃, 35℃, 30℃, 25℃, 22.5℃, 20℃, 17.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, and -15℃; the lower limit of the ambient temperature range includes 30℃, 25℃, and 22.5℃. The ambient temperature can be any one of the following: 20℃, 17.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, -15℃, -17.5℃, -20℃, -22.5℃, -25℃, -27.5℃, -30℃, -32.5℃, -35℃, -37.5℃, -40℃, -42.5℃, -45℃, -47.5℃, or -50℃. Specifically, the ambient temperature value includes at least one integer temperature within the range of -50℃ to 50℃, ±0.5℃.

[0036] It should be noted that the inventor's purpose in adjusting the battery ambient temperature is to extend the total cumulative lifespan of the lithium battery, but this does not limit the application of this solution in charge-discharge cycle scenarios. Because the number of charge-discharge cycles is only a superficial indicator, adjusting the battery ambient temperature may not necessarily extend the charge-discharge cycle lifespan, but the number of charge-discharge cycle lifespans does not affect the total cumulative lifespan of the lithium battery. This solution can substantially extend the total cumulative lifespan of the lithium battery, and this effect is unaffected by whether or not cycle count is used to describe the battery performance degradation process.

[0037] In some embodiments, the SOH index includes one or more of the following: actual maximum energy storage capacity, actual maximum energy storage capacity attenuation, actual maximum power storage capacity, actual maximum power storage capacity attenuation, relative energy storage capacity, relative energy storage capacity attenuation, relative power storage capacity attenuation, actual internal resistance, actual internal resistance attenuation, single actual discharge duration, single actual discharge duration attenuation, relative discharge duration, single actual charging duration, single actual charging duration attenuation, relative charging duration, actual work done by the battery's actual maximum energy storage capacity for the operation of power-consuming equipment, and mileage generated by the battery's actual maximum energy storage capacity for vehicle driving.

[0038] It's important to note that SOH (State of Health) is a crucial indicator for measuring the degree of battery performance degradation, typically used to describe the battery's current health and performance. SOH is expressed as a percentage, with 100% SOH meaning the battery's performance is exactly the same as when it left the factory. The formula for calculating SOH is: Current Performance / Initial Performance × 100%. Current performance refers to the battery's capabilities in its current state, potentially involving factors such as capacity and output power; initial performance refers to the battery's original performance state at the time of manufacture. Over time and with increased battery use, battery capacity and performance typically decline gradually. This decline is reflected in the gradual decrease in SOH. For example, if a battery's current capacity is only 80% of its initial capacity, then its SOH is 80%. In this solution, the SOH indicator includes information on changes in battery performance characteristics, used to measure the degree of battery performance loss or health status.

[0039] In some embodiments, the cumulative usage is the cumulative result of the actual usage measurement of the battery. The cumulative usage at a specific time is calculated as the cumulative result of the actual usage measurement generated within the time range from when the battery is put into use to the time before the specific time.

[0040] The cumulative usage of a battery increases with daily use. This cumulative usage is closely related to the measurement time; different measurement times may yield different cumulative usage values. The specific time mentioned here is intended to illustrate the relationship between the two. The emphasis on "specific time" does not imply a limitation on the value of that time, but merely indicates that the cumulative usage value is related to a specific time. When calculating the cumulative usage, the corresponding measurement time must be clearly defined.

[0041] In some implementations, the types of cumulative usage include one or more of the following: cumulative charging amount, cumulative discharging amount, cumulative absolute value charging and discharging amount, cumulative charging time, cumulative discharging time, cumulative charging and discharging time, cumulative idle time, cumulative charging times, cumulative discharging times, cumulative charging and discharging times, cumulative idle times, calendar service time, cumulative result of actual workload generated by the operation of battery-powered equipment, cumulative result of actual work done by the operation of battery-powered equipment, and cumulative result of actual mileage generated by the battery for vehicle driving.

[0042] Specifically, cumulative charge amount refers to the total amount of electricity charged into the battery during its entire use, usually measured in Ah; cumulative discharge amount refers to the total amount of electricity discharged into the battery during its entire use, usually measured in Ah; cumulative absolute charge / discharge amount refers to the total absolute amount of charge / discharge into the battery during its entire use, usually measured in Ah; cumulative charging time refers to the total charging time into the battery during its entire use, usually measured in hours; cumulative discharging time refers to the total discharging time into the battery during its entire use, usually measured in hours; and cumulative charge / discharge time refers to the total charge / discharge time into the battery during its entire use, usually measured in hours. The terms "cumulative idle time" and "cumulative charge / discharge" refer to the total idle time of the battery during its entire use, usually measured in hours. The terms "cumulative charge / discharge" and "cumulative idle time" refer to the total number of times the battery has been charged during its entire use, usually measured in times. The terms "cumulative discharge" and "cumulative charge / discharge" refer to the total number of times the battery has been charged and discharged during its entire use, usually measured in times. The terms "cumulative idle time" refer to the total number of times the battery has been idle during its entire use, usually measured in times. The terms "cumulative calendar service time" refer to the total time the rechargeable battery has been in service from its production date to the current date, usually measured in days.

[0043] This section uses cumulative discharge as an example to illustrate the practical significance of cumulative usage. Cumulative discharge represents the amount of electricity a battery has discharged from the time it is put into use until a certain point in its operation. From the moment a battery is put into use, it continuously undergoes charging and discharging. The cumulative discharge is obtained by summing the electricity discharged during each discharge cycle. Similarly, cumulative usage can also include cumulative charge, cumulative discharge, and cumulative absolute charge / discharge. Batteries with high cumulative charging time, cumulative discharging time, and cumulative charge / discharge time usually indicate more frequent use, which significantly affects the battery's total cumulative lifespan; therefore, these three are included in cumulative usage. Similarly, cumulative usage can also include cumulative idle time, cumulative number of charges, cumulative number of discharges, cumulative number of charge / discharge cycles, and cumulative number of idle cycles.

[0044] In some embodiments, the total cumulative lifespan is calculated as the cumulative usage from the time the battery is put into use until the SOH index reaches the failure threshold; the failure threshold is a value within the range of the battery's SOH index, and when the SOH index reaches the failure threshold, the battery can no longer work stably.

[0045] The failure threshold can be a pre-set value, that is, a value within the range of the battery's SOH index. For example, if the failure threshold is pre-set to 20% of the battery's rated capacity, then for a battery with a rated capacity of 1000mAh, its failure threshold is 200mAh. When the SOH index reaches 200mAh, the cumulative usage corresponding to that point on the degradation curve is the total cumulative lifespan under that failure threshold.

[0046] Step S120: Obtain the SOH loss due to temperature drop based on the degradation curve; and obtain the SOH loss due to temperature drop caused by different temperature drops under a specific cumulative usage based on the real-time effect of ambient temperature on the SOH index.

[0047] It should be noted that the SOH loss due to temperature drop includes the immediate loss of the SOH index value after the battery's body temperature changes. Here, "immediate effect" is used to describe the impact of ambient temperature on the SOH index, meaning that the battery's SOH index is very sensitive to transient changes in ambient temperature. Even a small, instantaneous change in ambient temperature will cause a significant change in the SOH index. As shown in Figure 3, within a short observation period, disturbances in ambient temperature will cause the battery's SOH index to fluctuate around the baseline degradation curve.

[0048] The temperature drop SOH loss is also affected by operating conditions. When operating conditions change, the temperature drop SOH loss will also change accordingly. Therefore, the influence of operating conditions should be considered when calculating the temperature drop SOH loss. Specifically, operating conditions include various operating conditions during battery operation. In the actual operation of the battery, different operating condition settings will affect the battery performance, and at the same time affect the dynamic changes of temperature drop SOH loss and temperature drop lifetime gain. The types of operating conditions that can be selected include: the specific changes or average values ​​of the battery's output current, output voltage, and output power during battery operation; air humidity, heat dissipation conditions, air pressure conditions; equipment operating power; equipment production efficiency; vehicle speed, etc.

[0049] Specifically, output current refers to the magnitude of the current output through the positive and negative terminals of the rechargeable battery, while output power refers to the magnitude of the power output through the positive and negative terminals. Generally, the product of output voltage and output current is the output power. In practical battery applications, output current often varies. However, due to the internal resistance of the rechargeable battery, different current magnitudes result in different internal energy losses, altering the internal cell temperature and consequently affecting the battery surface temperature, thus changing the calculated temperature drop (SOH) loss. Simultaneously, battery performance inevitably degrades in practical applications. This degradation manifests as a gradual increase in internal resistance, leading to increased internal energy losses. The increased internal resistance causes a gradual decrease in the battery's output voltage. As the output voltage decreases, the battery voltage reaches the failure threshold more easily, causing premature battery failure and thus altering the calculated temperature drop lifetime gain.

[0050] During battery operation, air humidity and air pressure conditions affect the electrochemical reaction rate, thus impacting battery performance; heat dissipation conditions affect the battery surface temperature, thereby influencing the amount of SOOH loss due to temperature drop and the gain in battery life due to temperature drop. Therefore, air humidity, heat dissipation conditions, and air pressure conditions are also included in the operating conditions. Equipment operating power refers to the actual operating power of the power-consuming equipment when the battery is supplying it for normal operation; equipment production efficiency refers to the workload that the power-consuming equipment can generate per unit time when the battery is supplying it for normal operation; vehicle speed refers to the distance that the vehicle can travel per unit time when the battery is supplying it for normal operation.

[0051] In some embodiments, the method for calculating the SOH loss due to temperature drop is as follows: for a battery with a specific cumulative usage, the SOH index value corresponding to the battery body temperature at a certain temperature T1 is represented by R1, and the SOH index value corresponding to the battery body temperature at another temperature T2 is represented by R2. The difference between R1 and R2 is the SOH loss due to temperature drop, wherein the value of T2 is lower than the value of T1.

[0052] The upper and lower limits of the value ranges of T1 and T2 are consistent with the upper and lower limits of the ambient temperature, that is, the values ​​of T1 and T2 include ±0.5℃ of at least one integer temperature between -50℃ and 50℃. The magnitude of the SOH loss due to temperature drop will change with the specific cumulative usage, T1, and T2. The variation of the SOH loss due to temperature drop with cumulative usage, T1, and T2 can be reflected by the temperature drop performance loss model.

[0053] The temperature drop performance loss model includes both simple mathematical models and complex neural network models. Common mathematical models include stochastic models, continuous-time models, discrete-time models, difference equation models, algebraic equation models, differential equation models, systems of equations models, linear models, nonlinear models, regression models, Markov chain models, and stochastic process models. Common neural network models include support vector machines, deep learning networks, extreme learning networks, recurrent neural networks, generative adversarial networks, convolutional neural networks, long short-term memory networks, autoencoders, Boltzmann machines, and deep belief networks. The specific model type can be flexibly selected based on the actual deployment and application scenario. The specific construction method is as follows: first, a suitable neural network model structure is selected; then, the selected neural network model structure is trained based on the battery's historical data; finally, a complete neural network model is generated and constructed.

[0054] Specifically, mathematical models are established based on the understanding of the physical and chemical laws governing the battery charging and discharging process. Common mathematical models include: stochastic models, which consider random factors in the battery charging and discharging process, such as changes in ambient temperature and load current; continuous-time models, which treat the battery charging and discharging process as a continuous process and describe it using mathematical tools such as differential equations; discrete-time models, which treat the battery charging and discharging process as a discrete process and describe it using mathematical tools such as difference equations; difference equation models, which use difference equations to describe the changes in state variables such as voltage, current, and energy storage capacity; algebraic equation models, which use algebraic equations to describe the static characteristics of the battery, such as open-circuit voltage and internal resistance; differential equation models, which use differential equations to describe the dynamic characteristics of the battery, such as the changes in state variables such as voltage, current, and energy storage capacity; system of equations models, which use multiple equations to describe multiple state variables or characteristics of the battery; linear models, which assume a linear relationship between the battery's state variables and independent variables; and nonlinear models, which do not assume a linear relationship between the battery's state variables and independent variables. Regression models use statistical methods to establish the relationship between the battery's state variables and independent variables. Markov chain models treat the battery's states as discrete states and use Markov chains to describe the transition probabilities between states. Stochastic process models use stochastic processes to describe the changing patterns of the battery's state variables.

[0055] Neural network models are machine learning models inspired by biological nervous systems. They can learn complex nonlinear relationships from data and are used for various prediction tasks. Common neural network models include: Support Vector Machines (SVMs), a supervised learning algorithm used for classification and regression; Deep Learning Networks (DNNs), neural networks composed of multiple hidden layers with powerful feature extraction and learning capabilities; Extreme Learning Networks (ELNs), a type of fast-learning neural network that can achieve good performance on relatively small datasets; Recurrent Neural Networks (RNNs), capable of handling sequential data, such as time series data; Generative Adversarial Networks (GANs), a model composed of two neural networks, one for generating data and the other for judging the authenticity of data; Convolutional Neural Networks (CNNs), adept at handling image data; Long Short-Term Memory (LSTM) networks, a type of recurrent neural network capable of handling long-range dependencies; Autoencoders (Autoencoders), a type of neural network used for dimensionality reduction and feature extraction; Boltzmann Machines (BLMs), a probability-based model capable of learning the distribution of data; and Deep Belief Networks (DBNs), a model composed of multiple autoencoders with hierarchical feature representation capabilities.

[0056] When selecting a specific model for temperature drop performance loss models, the following factors need to be considered: 1. Data availability: If sufficient historical data is available, data-driven models, such as neural network models, can be used; if the amount of data is limited, models based on physical laws, such as mathematical models, can be used. 2. Model complexity: Complex models often have higher accuracy but also require more computational resources; the appropriate model complexity should be selected based on the actual application scenario. 3. Model robustness: The model should be able to handle rechargeable batteries under various operating conditions. 4. Model interpretability: If understanding the model's prediction results is required, a model with strong interpretability should be selected.

[0057] Step S130: Obtain the temperature drop lifetime gain based on the degradation curve, and obtain the temperature drop lifetime gain caused by different temperature drops under a specific cumulative usage based on the long-term influence of the ambient temperature on the degradation curve.

[0058] It should be noted that the term "long-term impact" is used here to describe the effect of ambient temperature on the degradation rate. This means that ambient temperature may fluctuate frequently and instantaneously, but the rate of change of the battery degradation curve is usually difficult to change significantly in a short period of time. In other words, the total cumulative battery life is usually difficult to change significantly in a short period of time. Therefore, to accurately assess the impact of ambient temperature on the cumulative battery life, continuous observation and analysis are required over a relatively long observation window. The term "long-term" here is intended to reveal the persistence and cumulative nature of this impact.

[0059] Among them, the temperature drop lifetime gain includes the increase in total cumulative lifetime caused by the slowdown in the degradation rate of the battery when it is running at a low body temperature for a long time. The temperature drop lifetime gain is also affected by the operating conditions. When the operating conditions change, the temperature drop lifetime gain will also change accordingly. When calculating the temperature drop lifetime gain, the influence of the operating conditions must also be considered, just like in step S120.

[0060] In some embodiments, the temperature drop lifetime gain is calculated as follows: for a battery with a specific cumulative usage, the total expected cumulative lifetime when the battery body temperature is at a certain temperature T1 is represented by L1, and the total expected cumulative lifetime when the battery body temperature is at a certain temperature T2 is represented by L2. The difference between L1 and L2 is the temperature drop lifetime gain, where the value of T2 is lower than the value of T1. The magnitude of the temperature drop lifetime gain changes with the specific cumulative usage, T1, and T2; the variation law of the temperature drop lifetime gain with cumulative usage, T1, and T2 can be summarized by constructing a temperature drop lifetime gain model.

[0061] This section clarifies the meaning of "specific cumulative usage": the values ​​of SOH loss due to temperature drop and lifespan gain due to temperature drop are related to the current ambient temperature, the temperature drop rate, and the optimal ambient temperature, and are also closely related to the battery's current cumulative usage. It's emphasized that "specific cumulative usage" does not limit the value of the cumulative usage; it merely illustrates that the values ​​of SOH loss due to temperature drop and lifespan gain due to temperature drop are related to changes in cumulative usage. When calculating the optimal ambient temperature and temperature drop rate, the value of the cumulative usage needs to be clearly defined first. Simply put, when calculating the lifespan gain and SOH loss due to temperature drop, the battery's cumulative usage needs to be obtained beforehand, and then, based on the constructed mathematical model or a trained AI model, the corresponding lifespan gain and SOH loss due to temperature drop can be obtained.

[0062] Temperature drop lifetime gain models include both simple mathematical models and complex neural network models. Common mathematical models include stochastic models, continuous-time models, discrete-time models, difference equation models, algebraic equation models, differential equation models, systems of equations models, linear models, nonlinear models, regression models, Markov chain models, and stochastic process models. Common neural network models include support vector machines, deep learning networks, extreme learning networks, recurrent neural networks, generative adversarial networks, convolutional neural networks, long short-term memory networks, autoencoders, Boltzmann machines, and deep belief networks. The specific model type can be flexibly selected based on the actual deployment and application scenario. The specific construction method is as follows: first, select a suitable neural network model structure; then, train the selected neural network model structure based on the battery's historical data; finally, generate and construct a complete neural network model. The selection of a specific model type for the temperature drop lifetime gain model can refer to the approach for temperature drop performance loss models.

[0063] Step S140: Calculate the optimal ambient temperature. By weighing the negative impact of the temperature drop on the SOH index and the positive impact of the temperature drop on the total cumulative lifetime, the optimal ambient temperature is calculated.

[0064] Among them, the temperature drop SOH loss represents the degree of loss of battery capacity due to the temperature drop, and the temperature drop lifetime gain represents the degree of improvement of the battery's total cumulative lifetime due to the temperature drop. By reasonably selecting the temperature drop range, these two values ​​can be determined to double the battery's total cumulative lifetime without seriously affecting the single-charge range performance.

[0065] In some embodiments, when weighing the negative impact of cooling amplitude on the SOH index and the positive impact of cooling amplitude on the total cumulative lifespan, a weighting coefficient A is set and multiplied by the SOH loss due to temperature drop, and a weighting coefficient B is set and multiplied by the lifespan gain due to temperature drop. The two products are then added together to obtain a comprehensive weighting index. The ambient temperature of the battery is adjusted to adjust the cooling amplitude so that the comprehensive weighting index is maximized. The ambient temperature at which the comprehensive weighting index is maximized is the optimal ambient temperature. The weighting coefficients A and B are preset or obtained after training a mathematical model. The values ​​of the weighting coefficients A and B can be positive or negative. This allows for a comprehensive consideration of the negative impact of cooling amplitude on the SOH index and the positive impact of cooling amplitude on the total cumulative lifespan.

[0066] Specifically, adjusting the ambient temperature of the battery can change the cooling rate, thereby affecting the value of the comprehensive trade-off index. When the value of the comprehensive trade-off index is at its maximum, the ambient temperature is the optimal ambient temperature. Maintaining the ambient temperature at the optimal ambient temperature can achieve dual optimization of temperature drop lifespan gain and temperature drop SOH loss.

[0067] In some embodiments, the upper and lower limits of the optimal ambient temperature range are consistent with the upper and lower limits of the ambient temperature range, that is, the optimal ambient temperature is ±0.5°C of at least one integer temperature between -50°C and 50°C.

[0068] Step S150: Adjust the battery's body temperature and dynamically adjust the ambient temperature of the battery to keep the battery's body temperature within ±2℃ of the optimal ambient temperature.

[0069] The types of batteries mentioned in this plan include: lithium batteries, lithium-ion batteries, lithium-sulfur batteries, sodium batteries, sodium-ion batteries, aluminum batteries, aluminum-ion batteries, air-type batteries, graphene batteries, sulfur batteries, nickel-metal hydride batteries, lead-acid batteries, all-solid-state batteries, solid-liquid hybrid batteries, metal batteries, metal-ion batteries, cylindrical batteries, polymer batteries, power batteries, halide batteries, silicon-based batteries, supercapacitors, fuel cells, or other energy storage devices that can be discharged; different battery models can be used when conducting long-term degradation tests on batteries at a series of ambient temperatures.

[0070] In this solution, to precisely extend the total cumulative battery life by reducing the ambient temperature, it is necessary to obtain the battery's intrinsic temperature, heat dissipation conditions, SOH loss due to temperature drop, lifespan gain due to temperature drop, and dynamically adjust the ambient temperature. During battery operation, the ambient temperature is constantly changing due to heat exchange between the battery surface and the environment, as well as the battery's heat dissipation conditions. Therefore, obtaining the battery's intrinsic temperature and heat dissipation conditions, combined with SOH loss due to temperature drop, lifespan gain due to temperature drop, and dynamically adjusting the ambient temperature, ensures that the battery operates at the optimal ambient temperature in real time, thereby extending the battery's total cumulative lifespan.

[0071] In this solution, to further extend the total cumulative battery life, auxiliary batteries can be added to increase the overall SOH index, compensate for the negative impact of reduced ambient temperature, and further increase the total cumulative life. Furthermore, based on a comprehensive consideration of economic efficiency and to fully meet actual usage needs, the optimal battery capacity, number of batteries, and ambient temperature are determined to maximize overall benefits.

[0072] In the specific experiments conducted according to the above steps, as shown in Figure 4, a multi-cell series compensation method was used to compensate for the SOH loss caused by the temperature drop in this low-temperature life extension method. Multiple degradation curves were obtained by conducting random incomplete charge-discharge tests on multiple batteries of the same model. The SOH index and total cumulative lifespan of two batteries under low-temperature conditions were twice that of a single battery under low-temperature conditions; the total cumulative lifespan of two batteries under low-temperature conditions was four times that of a single battery under low-temperature conditions. As can be seen from Figure 4, setting a low-temperature environment nearly doubles the total cumulative lifespan, and connecting double the number of batteries in series also nearly doubles the total cumulative lifespan. In other words, setting a low-temperature environment and connecting batteries in series can increase the total cumulative lifespan by nearly four times.

[0073] This indicates that although the SOH index of a single battery will decrease in a low-temperature environment, for example, by 20% as shown in Figure 4, the SOH index of two batteries of the same type connected in series in a low-temperature environment is higher than that of a single battery at the reference operating temperature, for example, by twice as shown in Figure 4. This makes up for the SOH loss caused by the temperature drop in a low-temperature environment and achieves a balance between low-temperature life extension and battery capacity decay.

[0074] It should be noted that the figures of one times, four times, 20%, etc. mentioned above are merely illustrative and are only used to help understand the method and core ideas proposed in this invention, and are by no means intended to limit this disclosure or its application or use.

[0075] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention. Industrial applicability

[0076] Generally, the industry widely believes that low-temperature environments are detrimental to battery operation. The technical solution provided in this invention doubles the total cumulative battery life without significantly affecting single-charge performance, thus significantly reducing battery replacement frequency and maintenance costs. This solution provides a method to extend the total cumulative battery life by lowering the ambient temperature, which can double the total cumulative battery life without significantly affecting single-charge performance, and has extremely high application prospects and economic value.

[0077] In summary, although low temperatures negatively impact battery capacity, this effect is not permanent. On the contrary, low temperatures significantly extend the battery's total lifespan. In other words, by adjusting the ambient temperature, battery lifespan can be increased by two to three times.

Claims

1. A method for extending the total cumulative lifespan of a battery by reducing ambient temperature, characterized in that, Includes the following steps: Obtain the degradation curve, set the ambient temperature, conduct a degradation test on the battery, and obtain the degradation curve of the battery SOH index with the cumulative usage under different ambient temperatures; The SOH loss due to temperature drop is obtained. Based on the real-time effect of ambient temperature on the SOH index, the SOH loss due to temperature drop caused by different temperature drop amplitudes is obtained. Obtain the temperature drop lifetime gain; based on the long-term influence of the ambient temperature on the degradation curve, obtain the temperature drop lifetime gain caused by different temperature drop amplitudes. The optimal ambient temperature is calculated by weighing the negative impact of the temperature drop on the SOH index and the positive impact of the temperature drop on the total cumulative lifetime through the SOH loss and the lifetime gain. Adjust the battery's internal temperature and dynamically adjust the ambient temperature to keep the battery's internal temperature within ±2℃ of the optimal ambient temperature.

2. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 1, characterized in that: When weighing the negative impact of temperature drop on the State of Health (SOH) index and the positive impact of temperature drop on the total cumulative lifespan, a weighting coefficient A is set and multiplied by the SOH loss due to temperature drop, and a weighting coefficient B is set and multiplied by the lifespan gain due to temperature drop. The two products are then added together to obtain a comprehensive weighting index. Adjusting the ambient temperature of the battery can change the temperature drop, thereby affecting the value of the comprehensive weighting index. When the value of the comprehensive weighting index is at its maximum, the ambient temperature is the optimal ambient temperature. The weighting coefficients A and B are preset or obtained after training a mathematical model, and their values ​​can be positive or negative.

3. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 2, characterized in that: The total cumulative lifespan is calculated as the cumulative usage from the time the battery is put into use until the SOH index reaches the failure threshold. The failure threshold is a value within the range of the battery's SOH index. When the SOH index reaches this failure threshold, the battery can no longer work stably.

4. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 1, characterized in that: The SOH index includes one or more of the following: actual maximum energy storage capacity, actual maximum energy storage capacity attenuation, actual maximum power storage capacity, actual maximum power storage capacity attenuation, relative energy storage capacity, relative energy storage capacity attenuation, relative power storage capacity attenuation, actual internal resistance, actual internal resistance attenuation, single actual discharge duration, single actual discharge duration attenuation, relative discharge duration, single actual charging duration, single actual charging duration attenuation, relative charging duration, actual work done by the battery's actual maximum energy storage capacity for power-consuming equipment operation, and the mileage generated by the battery's actual maximum energy storage capacity for vehicle driving.

5. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 1, characterized in that: The cumulative usage is the cumulative result of the actual usage measurement of the battery. The method for calculating the cumulative usage at a specific time is to calculate the cumulative result of the actual usage measurement generated within the time range from when the battery is put into use to the specific time.

6. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 5, characterized in that: The types of cumulative usage include one or more of the following: cumulative charging amount, cumulative discharging amount, cumulative absolute value charging and discharging amount, cumulative charging time, cumulative discharging time, cumulative charging and discharging time, cumulative idle time, cumulative charging times, cumulative discharging times, cumulative charging and discharging times, cumulative idle times, calendar service time, cumulative result of actual workload generated by the operation of battery-powered equipment, cumulative result of actual work done by battery-powered equipment, and cumulative result of actual mileage generated by battery-powered vehicle driving.

7. The method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 1, characterized in that: The method for calculating the SOH loss due to temperature drop is as follows: for a battery with a specific cumulative usage, the SOH index value corresponding to the battery body temperature at a certain temperature T1 is represented by R1, and the SOH index value corresponding to the battery body temperature at another temperature T2 is represented by R2. The difference between R1 and R2 is the SOH loss due to temperature drop, where the value of T2 is lower than the value of T1.

8. A method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 7, characterized in that: The method for calculating the temperature drop life gain is as follows: for a battery with a specific cumulative usage, the total cumulative life expected to operate when the battery body temperature is at a certain temperature T1 is represented by L1, and the total cumulative life expected to operate when the battery body temperature is at a certain temperature T2 is represented by L2. The difference between L1 and L2 is the temperature drop life gain.

9. A method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to claim 8, characterized in that: The ambient temperature is ±0.5℃ of at least one integer temperature between -50℃ and 50℃. The values ​​of T1, T2, and the optimal ambient temperature are ±0.5℃ of at least one integer temperature between -50℃ and 50℃. The upper and lower limits of the range of T1, T2, and the optimal ambient temperature are consistent with the upper and lower limits of the range of ambient temperature.

10. A method for extending the total cumulative lifespan of a battery by reducing ambient temperature according to any one of claims 1-9, characterized in that: The upper limit of the ambient temperature range is one of the following: 50℃, 45℃, 40℃, 35℃, 30℃, 25℃, 22.5℃, 20℃, 17.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, and -15℃; the lower limit of the ambient temperature range is one of the following: 30℃, 25℃, 22.5℃, 20℃, and 17.5℃. One of the following: 7.5℃, 15℃, 12.5℃, 10℃, 7.5℃, 5℃, 2.5℃, 0℃, -2.5℃, -5℃, -7.5℃, -10℃, -12.5℃, -15℃, -17.5℃, -20℃, -22.5℃, -25℃, -27.5℃, -30℃, -32.5℃, -35℃, -37.5℃, -40℃, -42.5℃, -45℃, -47.5℃, -50℃.

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