Pulse current charging heating method

Abstract

The invention discloses a pulse current charging heating method, and belongs to the technical field of battery management. The method comprises the following steps: applying periodic positive and negative pulse current to a battery according to a designed pair of positive and negative pulse current to obtain a to-be-detected battery; carrying out capacity testing on the to-be-tested battery to obtain an initial capacity; charging the to-be-tested battery, and acquiring data in the charging process; and based on the initial capacity, analyzing data in the charging process to obtain an analysis result, and making a battery charging heating scheme according to the analysis result. According to the method, a pulse heating mode is a group of pulse sequences, each pulse sequence comprises a positive square wave pulse current and a negative square wave pulse current in one period, and the equivalent current of the positive square wave pulse is larger than that of the negative square wave pulse, so that the battery works under alternating current with direct current bias; therefore, the electric quantity of the battery is supplemented while heating is realized.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and more specifically to a pulse current charging and heating method. Background Technology

[0002] Lithium-ion batteries, with their advantages of high specific energy, low self-discharge rate, and long lifespan, have become the fastest-growing and most widely used power batteries, boasting enormous market potential. However, at low temperatures, the viscosity of the lithium-ion battery electrolyte increases, conductivity decreases, impedance increases rapidly, and peak power and usable energy drop sharply. Low-temperature charging easily leads to lithium plating on the negative electrode, causing a decrease in capacity and lifespan, and may even form lithium dendrites, triggering internal short circuits, thermal runaway, and increasing safety risks. Therefore, it is essential to perform low-temperature heating on lithium-ion batteries to improve their low-temperature charging and overall performance.

[0003] Currently, battery heating methods are mainly divided into two types: external heating and internal heating. External heating is simple in structure and low in cost, but during the heat transfer process, heat is absorbed by other heat exchange media, resulting in low heat exchange, low heating efficiency, and poor temperature uniformity. Furthermore, external heating of battery packs requires additional equipment or a specific layout design, increasing the complexity of the battery thermal management system. Among internal heating methods, all-weather batteries can achieve rapid and efficient battery heating. However, because the heating scheme requires changes to the battery's internal structure, there is significant uncertainty regarding battery safety. Current-excited heating does not require changes to the battery's internal structure, but DC self-heating wastes some energy and has low heating efficiency; AC self-heating keeps the battery capacity unchanged but requires an AC power source, increasing the complexity of the heating circuit; pulse current heating provides rapid temperature rise, uniform heating, and low requirements for external power supply, but it cannot solve the problem of reduced SOC and poor battery life during use. Summary of the Invention

[0004] To address the problem of poor battery life caused by decreased battery capacity and lifespan at low temperatures in existing technologies, this invention provides a pulse current charging and heating method. In this method, the pulse heating mode is a series of pulses, each cycle of which includes a positive square wave pulse current and a negative square wave pulse current. The equivalent current of the positive square wave pulse is greater than that of the negative square wave pulse, causing the battery to operate under AC current with DC bias, thereby replenishing the battery's charge while simultaneously heating it.

[0005] To achieve the above objectives, the present invention provides the following technical solution.

[0006] This invention provides a pulse current charging and heating method, comprising: Based on the design of a pair of positive and negative pulse currents, a periodic positive and negative pulse current is applied to the battery to obtain the battery under test; Perform a capacity test on the battery under test to obtain its initial capacity; Charge the battery under test and acquire data during the charging process; Based on the initial capacity, the data during the charging process is analyzed to obtain the analysis results, and a battery charging and heating scheme is formulated based on the analysis results.

[0007] As a further improvement of the present invention, the design of a pair of positive and negative pulse currents includes: Positive pulse amplitude =Negative pulse amplitude ; Positive pulse duty cycle =Negative pulse duty cycle .

[0008] As a further improvement of the present invention, the step of applying a periodic positive and negative pulse current to the battery according to a designed pair of positive and negative pulse currents to obtain the battery under test includes: Based on the design of a pair of positive and negative pulse currents, positive and negative pulse currents are periodically applied to the battery during the charging process to promote the movement of molecules inside the battery, thus obtaining the battery under test.

[0009] As a further improvement of the present invention, the step of performing a capacity test on the battery under test to obtain an initial capacity includes: At a set ambient temperature, the capacity of the battery under test is tested to obtain the initial capacity of the battery at the set ambient temperature. The set ambient temperature is below 0°C.

[0010] As a further improvement of the present invention, the step of charging the battery under test and acquiring data during the charging process includes: Based on the state of charge of the battery under test, the battery is heated and charged by a pulse current with a set amplitude and frequency. The voltage, temperature rise, and capacity data of the battery under test are measured to generate data during the charging process.

[0011] As a further improvement of the present invention, the range of the set amplitude is 5.5C to 8.5C.

[0012] As a further improvement of the present invention, the state of charge of the battery under test is 20% to 80%.

[0013] As a further improvement of the present invention, the set frequency is 10Hz~1000Hz.

[0014] As a further improvement of the present invention, the step of analyzing data during the charging process based on the initial capacity to obtain analysis results, and formulating a battery charging heating scheme based on the analysis results, includes: Based on the initial capacity, the effects of frequency, amplitude and duty cycle on battery temperature rise, capacity and charging efficiency during the charging process are analyzed, and the analysis results are formed. A battery charging and heating scheme was developed based on the analysis results.

[0015] As a further improvement of the present invention, the battery charging heating scheme includes dynamically adjusting the pulse amplitude; optimizing the pulse frequency according to the SOC range; and matching the duty cycle with the charging stage.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves simultaneous, efficient heating and recharging of the battery in low-temperature environments by applying periodic positive and negative pulse currents to the battery through a specific design. This fundamentally solves the negative impact of low temperatures on battery performance, significantly improving the battery's practicality and reliability in cold environments. In terms of heating effect, the pulse heating mode employed in this invention consists of a pulse sequence that combines positive and negative square wave pulse currents within one cycle, ensuring that the equivalent current of the positive square wave pulse is greater than that of the negative square wave pulse, allowing the battery to operate in an AC state with DC bias. This unique current design enables rapid heat generation within the battery, achieving efficient heating. Compared to traditional heating methods, this method can raise the battery temperature to a suitable operating range more quickly, significantly shortening the heating time, improving the battery's response speed in low-temperature environments, and enabling the battery to recover normal performance more quickly, providing users with timely and stable power support. Attached Figure Description

[0017] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. In the drawings: Figure 1 This is a schematic flowchart of a pulse current charging and heating method according to the present invention; Figure 2 Heating mode diagram provided by the present invention; Figure 3 The figures show a comparison of the temperature rise rate of the traditional square wave pulse AC heating method; Figure (a) shows the result when the SOC is 20%; Figure (b) shows the result when the SOC is 50%; and Figure (c) shows the result when the SOC is 80%. Figure 4 The figures show a comparison of the temperature rise rate of the pulse current charging heating method of the present invention; wherein, Figure (a) is the result graph with a SOC of 20%; Figure (b) is the result graph with a SOC of 50%; and Figure (c) is the result graph with a SOC of 80%. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0020] This invention provides a heat insulation and heat preservation device that significantly improves the temperature retention efficiency of a battery by effectively suppressing heat loss during the heating process, thereby reducing energy consumption and improving heating performance.

[0021] A double-layered cuboid insulation box was made using silica nano-aerogel material. The battery clamp was placed in the insulation box and then placed in an incubator. The thermocouple was attached to the surface of the battery using electrical tape, with the thermocouple located in the middle of the battery. Silica nano-aerogel material was then wrapped around the outer surface of the battery to form a heat insulation device.

[0022] To address the problem of poor battery life caused by decreased battery capacity and lifespan at low temperatures in existing technologies, this invention provides a pulse current charging and heating method, such as... Figure 1 As shown, it includes: S100: Based on the design of a pair of positive and negative pulse currents, a periodic positive and negative pulse current is applied to the battery to obtain the battery under test; S200: Performs capacity testing on the battery under test to obtain the initial capacity; S300: Charges the battery under test and acquires data during the charging process; S400: Based on the initial capacity, analyze the data during the charging process to obtain the analysis results, and formulate a battery charging and heating scheme based on the analysis results.

[0023] In this method, the pulse heating mode is a series of pulses. One cycle of the pulse sequence contains a positive square wave pulse current and a negative square wave pulse current, and the equivalent current of the positive square wave pulse is greater than that of the negative square wave pulse, so that the battery operates on an AC power supply with DC bias, thereby replenishing the battery's charge while heating is achieved.

[0024] The present invention will be further explained and described below with reference to the accompanying drawings.

[0025] S1: As Figure 2 As shown, let the equivalent current of a positive square wave pulse be greater than the equivalent current of a negative square wave pulse. Let the amplitude of the positive pulse be... Equal to negative pulse amplitude Positive pulse duty cycle Equal to the negative pulse duty cycle .

[0026] Based on experimental requirements, a pair of positive and negative pulse currents are designed. The equivalent current of the positive square wave pulse is greater than that of the negative square wave pulse. Specifically, the following settings are made: Positive pulse amplitude =Negative pulse amplitude ; Positive pulse duty cycle =Negative pulse duty cycle .

[0027] The function of pulsed current is to periodically apply positive and negative pulsed current to the battery during the charging process, thereby promoting the movement of molecules inside the battery, increasing the battery's operating temperature, and reducing the performance degradation caused by low temperatures.

[0028] S2: The battery must meet the capacity requirement below 0°C when tested. For example, a capacity test is performed on the battery under test at an ambient temperature of -20°C to obtain the initial capacity of the battery at low temperature as baseline data. The purpose of this step is to provide initial reference values ​​for the subsequent evaluation of the heating effect of pulse current charging.

[0029] S3: Under an ambient temperature of -20℃, considering the battery's SOC (State of Charge) range (e.g., 20%~80%), the battery is heated and charged using pulse currents of different amplitudes (e.g., 5.5C~8.5C) and frequencies (e.g., 10Hz~1000 Hz), and the battery's voltage, temperature rise, capacity change, etc. are measured to obtain the measurement results; S4: Based on the measurement results of S3, formulate a battery charging plan, which must ensure that the battery voltage does not exceed the maximum voltage limit during the heating process.

[0030] Based on the results measured by S3, the effects of different frequencies, amplitudes, and duty cycles of the pulse current on battery temperature rise, capacity, and charging efficiency are analyzed. Considering factors such as battery type and operating environment, an optimal battery charging and heating scheme is formulated. This charging scheme can: Ensure efficient charging of the battery in low-temperature environments.

[0031] Increase the actual capacity of the battery and extend its lifespan.

[0032] Ensure safety during battery charging and avoid battery damage caused by overheating or overcharging.

[0033] This invention effectively replenishes battery power while simultaneously heating. Traditional heating methods often require additional electrical energy and cannot charge the battery during the heating process, leading to energy waste and low battery efficiency. The pulse current charging heating method of this invention, through a rational pulse current design, charges the battery using a positive square wave pulse current while heating it, achieving highly efficient energy utilization. This not only improves battery charging efficiency but also reduces energy consumption, extends the overall battery life, and saves users operating costs. Furthermore, this invention conducts detailed analysis of data during the charging process and develops a personalized battery charging and heating scheme based on the initial capacity. This precise control method can adjust pulse current parameters, such as pulse width and frequency, according to the actual state and needs of the battery, achieving precise optimization of the battery heating and charging process. This helps avoid damage to the battery caused by overheating or charging, extends battery life, and improves battery safety and stability. At the same time, the personalized charging and heating scheme can better adapt to different types and specifications of batteries, exhibiting broad applicability and compatibility. In summary, the pulse current charging and heating method of the present invention, through innovative pulse current design and precise control strategy, achieves efficient battery heating, power replenishment, and personalized management in low-temperature environments. It effectively solves the problem of poor battery life caused by the decline in battery capacity and lifespan at low temperatures in existing technologies, bringing new breakthroughs and opportunities for the development and application of battery technology, and has significant economic and social benefits.

[0034] In the field of new energy, low-temperature heating technology is crucial for battery applications in low-temperature environments. This invention considers parameters such as pulse heating mode, frequency, and amplitude, and then investigates the impact of different SOCs, positive and negative pulse current amplitudes, heating frequencies, and heating modes on the battery heating rate through experimental testing. This addresses issues such as battery capacity reduction, increased internal resistance, and shortened driving range in low-temperature environments. The pulse heating strategy proposed in this invention, combining pulse heating and charging, achieves efficient heating of the battery at low temperatures while simultaneously charging it, thus improving the battery's driving range.

[0035] The present invention will be further explained and described below with reference to specific embodiments.

[0036] The principle of pulsed current heating is that current flowing through the battery generates heat through its internal resistance. Battery heating includes reversible and irreversible heat. Reversible heat originates from reversible entropy changes during electrochemical reactions. Depending on the battery's charging or discharging process, entropy loss can be positive or negative. Irreversible heat is generated at the battery electrodes, electrolyte, and current collector. Irreversible heat is related to the current rate and can be expressed as follows:

[0037] in The calorific value of the battery. It is the root mean square value of the current. It is the real part of the battery impedance.

[0038] The formula for battery capacity is:

[0039] in This is the capacity value. The initial time, End time, This is the real-time current value.

[0040] The main reason for battery life degradation at low temperatures is lithium plating. The primary factor affecting lithium plating is the amplitude of the Faraday current. Since the large current amplitude of the battery is instantaneous, and most of the current flows through the non-Faraday path (electric double layer), the Faraday current is very small, making lithium plating highly unlikely. Furthermore, under high-frequency pulses, electrochemical polarization and concentration polarization are suppressed, and the battery voltage change is mainly caused by ohmic voltage drop, which does not cause lithium plating. Therefore, AC heating with constant polarization voltage will not produce lithium plating. The designed pulse heating charging mode has good heating effect and does not affect battery health, which is beneficial for promoting the application of electric vehicles in cold environments.

[0041] The effects of pulse heating mode on battery degradation and heating performance were investigated using AC heating tests over a wide frequency and SOC range. The tested battery was an 18650 lithium iron phosphate battery. To demonstrate the effectiveness of the proposed method, experimental comparison results with conventional AC pulse heating are provided. The parameters of the positive and negative square wave pulses in conventional AC heating are identical, i.e., no DC bias. The tested battery was heated from -20°C for 15 minutes before heating was stopped. The duty cycle of the positive and negative pulses in both pulse modes was 1:1. Table 1 lists the parameters of pulse heating.

[0042] Table 1 Pulse heating parameters

[0043] Pulse heating test results under different parameters are as follows Figure 3 and Figure 4As shown in the image, the heating effect improves as the pulse frequency decreases. (C) Taking the square wave pulse AC heating mode with a 16C battery SOC of 50% as an example, compared with 1000Hz, the temperature rise rates at 100Hz, 50Hz, and 10Hz increased by 21.88%, 45.83%, and 90.63%, respectively. This is because, as the frequency decreases, the tested batteries generally exhibit higher impedance, resulting in a greater heating rate and better heating effect. Additionally, increasing the current amplitude can significantly shorten the heating time. Taking the square wave pulse AC heating mode with a heating frequency of 10Hz and a battery SOC of 50% as an example, compared with... (C) Compared to 8C, the temperature rise rates at 12C and 16C increased by 67.53% and 137.66%, respectively. Additionally, the heating effect at battery SOCs of 20% and 80% was slightly better than at SOC 50%. (The heating frequency was 10Hz.) (C) Taking the square wave pulse AC heating mode with a SOC of 16C as an example, compared with a SOC of 50%, the temperature rise of SOCs of 20% and 80% increased by 6.01% and 7.10%, respectively.

[0044] The average heating rate of the square wave pulse heating and charging mode is 9.29% higher than that of the square wave pulse AC heating mode. Moreover, the square wave pulse heating and charging mode can also charge the battery during the heating process.

[0045] For example, when the battery's SOC is 50%, the temperature rise rate of the square wave pulse heating charging mode proposed in this application is 7.57% higher than that of the square wave pulse AC heating mode; the SOC increment is 11.35% higher than that of the square wave pulse AC heating mode; and the capacity increases by 0.1331 Ah during the 15-minute heating process. (See Table 2.) Table 2 Comparison of the two modes

[0046] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0047] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A pulse current charging and heating method, characterized in that, include: Based on the design of a pair of positive and negative pulse currents, a periodic positive and negative pulse current is applied to the battery to obtain the battery under test; Perform a capacity test on the battery under test to obtain its initial capacity; Charge the battery under test and acquire data during the charging process; Based on the initial capacity, the data during the charging process is analyzed to obtain the analysis results, and a battery charging and heating scheme is formulated based on the analysis results.

2. The pulse current charging and heating method according to claim 1, characterized in that, The design includes a pair of positive and negative pulse currents, comprising: Positive pulse amplitude =Negative pulse amplitude ; Positive pulse duty cycle =Negative pulse duty cycle .

3. The pulse current charging and heating method according to claim 1, characterized in that, The process of applying a pair of positive and negative pulse currents to the battery to obtain the battery under test includes: Based on the design of a pair of positive and negative pulse currents, positive and negative pulse currents are periodically applied to the battery during the charging process to promote the movement of molecules inside the battery, thus obtaining the battery under test.

4. The pulse current charging and heating method according to claim 1, characterized in that, The process of performing a capacity test on the battery under test to obtain its initial capacity includes: At a set ambient temperature, the capacity of the battery under test is tested to obtain the initial capacity of the battery at the set ambient temperature. The set ambient temperature is below 0°C.

5. The pulse current charging and heating method according to claim 1, characterized in that, The process of charging the battery under test and acquiring data during the charging process includes: Based on the state of charge of the battery under test, the battery is heated and charged by a pulse current with a set amplitude and frequency. The voltage, temperature rise, and capacity data of the battery under test are measured to generate data during the charging process.

6. The pulse current charging and heating method according to claim 5, characterized in that, The set amplitude range is 5.5C to 8.5C.

7. The pulse current charging and heating method according to claim 5, characterized in that, The state of charge of the battery under test is 20% to 80%.

8. The pulse current charging and heating method according to claim 5, characterized in that, The set frequency is 10Hz~1000Hz.

9. The pulse current charging and heating method according to claim 1, characterized in that, The process involves analyzing data during the charging process based on the initial capacity, obtaining analysis results, and formulating a battery charging and heating scheme based on these results, including: Based on the initial capacity, the effects of frequency, amplitude and duty cycle on battery temperature rise, capacity and charging efficiency during the charging process are analyzed, and the analysis results are formed. A battery charging and heating scheme was developed based on the analysis results.

10. The pulse current charging and heating method according to claim 9, characterized in that, The battery charging and heating scheme includes dynamically adjusting the pulse amplitude; optimizing the pulse frequency according to the SOC range; and matching the duty cycle with the charging stage.

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