Patent Application
20230384384
This application claims priority to and the benefit of Chinese Patent Application No. 202210587756.5, filed May 27, 2022, which are incorporated herein in their entireties by reference.
The invention relates generally to the field of lithium ion batteries, and more particularly to a method and a device for nondestructive detection of electrode lithium intercalation amount of lithium ion battery, and a battery management system.
In recent years, due to the increase of fossil energy crisis and environmental problems, new energy technologies such as wind energy technology and solar energy technology have developed rapidly. Due to the instability of the output power of the new energy system, it is necessary to introduce an energy storage system, and lithium-ion batteries have been widely used. In order to ensure the safety and reliability of lithium-ion batteries in long-term use, a battery management system (BMS) consisting of software and hardware is required to manage them. The currently widely used BMS are all developed based on the equivalent circuit model (ECM). Due to the limited predictive ability of ECM, the design of battery operation strategy is based on simple safety constraints, such as: a charge cutoff voltage, a discharge cutoff voltage, a maximum current, and the like.
However, the terminal voltage cannot fully reflect the internal state of the battery, especially at high currents, due to the large overpotential, which greatly increases or decreases the terminal voltage of the battery during charging and discharging. With the improvement of hardware computing power, a new type of more intelligent and advanced BMS based on electrochemical model (EM) is applied. Because EM can fully reflect the internal state of the battery, such as: positive and negative lithium ion concentration distribution, potential distribution, overpotential, etc., the capacity of lithium-ion batteries can be maximized to achieve greater economic benefits. The EM involves a large number of coupled partial differential equations, especially dozens of physical parameters, which makes the EM model limited in practical applications.
In order to obtain these parameters, such as the amount of lithium intercalation of the positive and negative electrodes, it is generally necessary to disassemble the battery and conduct experiments to obtain the parameters, but is these methods are usually very complicated and time-consuming, and can only obtain one-time parameters. Related parameters cannot be monitored in the using process of the battery.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.
In view of the above-noted shortcomings of the prior art, one of the objectives of this invention is to provide a method for detecting the lithium intercalation amount of the lithium ion battery electrodes, a detection device and a battery management system based on the detection method, which are nondestructive to the lithium ion battery and can be repeatedly carried out.
In order to achieve the above objectives, one aspect of the invention provides a method for detecting amounts of lithium intercalation in electrodes of a lithium ion battery, which is used for nondestructive electrode detection of the lithium ion battery.
The method includes acquiring a range of a positive electrode lithium intercalation amount and a range of a negative electrode lithium intercalation amount in a set charge-discharge cycle of the lithium ion battery; obtaining at least one first characteristic point (x1, Vp1) on a first characteristic curve Vp(x) of a potential Vp of a positive electrode material and a lithium intercalation amount x of the positive electrode within the range of the positive electrode lithium intercalation amount, and obtaining at least one second characteristic point (y2, Vn2) on a second characteristic curve Vn(y) of a potential Vn of a negative electrode material and a lithium intercalation amount y of the negative electrode within the range of the negative electrode lithium intercalation amount; obtaining a relation curve Q(Vocv) or Vocv(Q) of a charging capacity and an open-circuit voltage of the lithium ion battery; obtaining a third characteristic point (Vocv1, Q1) on the relation curve Q(Vocv) or Vocv(Q) corresponding to the first characteristic point, and a fourth characteristic point (Vocv2, Q2) on the curve Q(Vocv) or Vocv(Q) corresponding to the second characteristic point; and calculating parameters of the lithium intercalations of the positive and negative electrodes including: calculating a positive electrode full discharge lithium intercalation amount x0, a positive electrode full charge lithium intercalation amount x100%, a negative electrode full discharge lithium intercalation amount y0, and a negative electrode full charge lithium intercalation amount y100%, according to the data of the first characteristic point, the second characteristic point, the third characteristic point, and the fourth characteristic point.
In one embodiment, the step of calculating the parameters of the lithium intercalation amounts of the positive and negative electrodes comprises solving equations of:
wherein x2 is the positive electrode lithium intercalation amount obtained according to the first characteristic curve Vp(x) after a positive electrode potential Vp2=Vocv2+Vn2 corresponding to the fourth characteristic point is calculated, and y1 is the negative electrode lithium intercalation amount obtained according to the second characteristic curve Vn(y) after a negative electrode potential Vn1=Vp1−Vocv1 corresponding to the third characteristic point is calculated,
In one embodiment, the first characteristic point (x1, Vp1) is obtained through extremum points of a differential curve dVp(x)/dx of the first characteristic curve Vp(x); and the second characteristic point (y2, Vn2) is obtained through extremum points of a differential curve dVn(y)/dy of the second characteristic curve Vn(y); the third characteristic point (Vocv1, Q1) is obtained by comparing a differential curve of the curve Q(Vocv) with the differential curve dVp(x)/dx of the is first characteristic curve Vp(x), or comparing a differential curve of the curve Vocv(Q) with the differential curve dVp(x)/dx of the first characteristic curve Vp(x); and the fourth characteristic point (Vocv2, Q2) is obtained by comparing a differential curve of the curve Q(Vocv) with the differential curve dVn(y)/dy of the second characteristic curve Vn(y), or comparing a differential curve of the curve Vocv(Q) with the differential curve dVn(y)/dy of the second characteristic curve Vn(y).
In one embodiment, when the differential curve dVp(x)/dx of the first characteristic curve Vp(x) has multiple extremum points, the first characteristic point (x1, Vp1) is obtained according to one extremum point having the largest or smallest value; and when the differential curve dVn(y)/dy of the second characteristic curve Vn(y) has multiple extremum points, the second characteristic point (y2, Vn2) is obtained according to one extremum point having the largest or smallest value. In one embodiment, the step of obtaining the curve Q(Vocv) Vocv(Q) of the charging capacity and the open-circuit voltage of the lithium ion battery comprises: measuring a terminal voltage curve of the lithium ion battery in the charging and discharging process with a small current rate, and approximating the terminal voltage curve as an open-circuit voltage curve Vocv(t) of the lithium ion battery, wherein t is the charging and discharging time; obtaining a charging capacity curve Q(t) of the lithium ion battery by integrating the charging and discharging current I; and obtaining the curve Q(Vocv) or Vocv(Q) according to the open circuit voltage curve Vocv(t) and the charging capacity curve Q(t) of the lithium ion battery. In one embodiment, the charging and discharging current I adopted in the charging and discharging process with the small current rate is a constant current, and the charging and discharging rate is not greater than C/20. The charging and discharging process with the small current rate includes small current rate charging processes and small current rate discharging processes; and the open circuit voltage curve Vocv(t) and the charging capacity curve Q(t) are obtained by averaging data obtained from at least one of the small current rate charging processes and at least one of the small current discharge processes.
In one embodiment, the first characteristic curve Vp(x) and the second characteristic curve Vn(y) are obtained by half-cell testing, or by known characteristic curves of the positive electrode material and the negative electrode material.
In one embodiment, in the charging and discharging process with a small current rate, the lithium ion battery is placed in an environment with a constant temperature and a constant humidity.
Another aspect of the invention also provides a lithium-ion battery electrode lithium intercalation detection device, which uses any of the above-mentioned detection methods for the lithium-ion battery positive and negative lithium intercalation detection methods to perform non-destructive electrode detection on the lithium-ion battery.
Yet another aspect of the invention also provides a battery management system, including the aforementioned device for detecting the amount of lithium intercalated in the positive and negative electrodes of the lithium-ion battery, and the function of the battery management system includes non-destructive electrode detection of the lithium-ion battery.
Various embodiments of the invention have at least one of the following technical effects:
The accompanying drawings illustrate one or more embodiments of the invention and, together with the written description, serve to explain the principles of the invention. The same reference numbers may be used throughout the is drawings to refer to the same or like elements in the embodiments.
Embodiments of the invention are described below through specific examples in conjunction with the accompanying drawings in
It should be noted that the drawings provided in the following embodiments are merely illustrative in nature and serve to explain the principles of the invention, and are in no way intended to limit the invention, its application, or uses. Only the components related to the invention are shown in the drawings rather than the number, shape and size of the components in actual implementations. For components with the same structure or function in some figures, only one of them is schematically shown, or only one of them is marked. They do not represent the actual structure of the product. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily in its actual implementations. More complicate component layouts may also become apparent in view of the drawings, the specification, and the following claims.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, “a” not only means “only one”, but also means “more than one”. The term “and/or” used in the description of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations. The terms “first”, “second”, etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.
Unless otherwise clearly defined, the terms “installation” and “connection” should be interpreted in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be directly connected, or indirectly connected through an intermediary, or it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.
As shown in
At step S100, acquiring lithium intercalation ranges of electrodes. Specifically, a positive electrode lithium intercalation range and a negative electrode lithium intercalation range in a set charge-discharge cycle of the lithium ion battery are obtained. The set charge-discharge cycle refers to a discharge cycle in which the open-circuit voltage (OCV) of the lithium ion battery is discharged from the charge cutoff voltage to the discharge cutoff voltage, or a charge cycle in which the lithium ion battery is charged from the discharge cutoff voltage to the charge cutoff voltage. For convenience of the description, the battery charge capacity (amount) is normalized in this specification: when the lithium ion battery is charged to the charge cutoff voltage, the battery charge capacity corresponds to a full state, the corresponding battery state of charge (SOC) is 1, or the battery charge capacity Q=1. When the lithium ion battery is discharged to the discharge cutoff voltage, the corresponding SOC is 0, or the battery charge capacity Q=0. In order to prevent capacity loss caused by overcharge and overdischarge of the lithium ion battery, lithium intercalation ranges of the positive and negative electrodes in the charge-discharge cycles need to be set. Therefore, only the electrode parameters within the above ranges of lithium intercalation amounts need to be considered.
S200, obtaining a first characteristic point and a second characteristic point is on the characteristic curves of electrode potentials. Specifically, within the range of the positive electrode lithium intercalation amount, at least one first characteristic point (x1, Vp1) is obtained on a first characteristic curve Vp(x) of a potential Vp of a positive electrode material and a lithium intercalation amount x of the positive electrode; and within the range of the negative electrode lithium intercalation amount, at least one second characteristic point (y2, Vn2) is obtained on a second characteristic curve Vn(y) of a potential Vn of a negative electrode material and a lithium intercalation amount y of the negative electrode. The intercalated matter in the positive and negative electrodes can undergo a reversible phase change during the lithium intercalation or lithium deintercalation process of the positive and negative electrode materials, and the lithium intercalation amounts and electrode potentials corresponding to the phase transition point constitute the characteristic points of the corresponding positive and negative electrode materials, which have specificity and repeatability. Meanwhile, the difference between the lithium intercalation potentials of the positive and negative electrodes is the open circuit voltage of the lithium ion battery, and the lithium intercalation is related to the state of charge (SOC) of the lithium ion battery. Therefore, the lithium intercalation parameters of the positive and negative electrodes can be calculated by utilizing the characteristic points and combining with the measurement data in the charging and discharging process.
S300, obtaining a small current rate charging and discharging curve Vocv(t). Specifically, a terminal voltage curve of the lithium ion battery is measured during charging and discharging at a small current rate. The terminal voltage curve is approximated as an open-circuit voltage curve Vocv(t) of the lithium ion battery, wherein t is the charging and discharging time. A charging capacity curve Q(t) of the lithium ion battery is obtained by integrating the charging and discharging current I.
As used in the disclosure, the letter Q represents the charging capacity of the battery, and the letter C represents the capacity of the battery, which are related. The former is used to represent the charging capacity of the lithium ion battery relative to the fully discharged state, and the latter is equivalent to the capacity of the battery when charged to the charging cutoff voltage, that is, the fully charged state. Each variable in the disclosure is represented by a letter or a letter with a subscript, such as x represents the lithium intercalation amount of the positive electrode; the subscript p represents the positive electrode, the subscript n represents the negative electrode, and the subscript ocv represents the open circuit voltage. See Table 1 below for details. For the sake of brevity, when a certain variable also serves as an independent variable in an explanatory statement or in a complex formula, the independent variable corresponding to the variable, such as time t, is not indicated. For example, the lithium intercalation amount x(t) of the positive electrode is a variable with the charge and discharge time t as the independent variable, but when it is not necessary or the lithium intercalation amount of the positive electrode itself is used as the independent variable, it is simply expressed by x and no longer indicates the independent variable t. When each variable has a digital subscript, it refers to the specific value of the variable at a certain characteristic point, such as x1 represents the positive electrode lithium intercalation amount of the first characteristic point, or Q1 represents the battery charging capacity of the third characteristic point (For the third characteristic point, refer to step S400 for details).
The small current rate charging and discharging refers to the charging and discharging current I is much smaller than that at the standard charging and discharging rate. Since the charging and discharging rate is very small, the overpotential of the lithium ion battery can be ignored. At this time, the terminal voltage curve of the lithium ion battery can be accurately used as the open-circuit voltage curve Vocv(t) of the lithium ion battery, which satisfies the following relationship: Vocv(t)=Vp(t)−Vn(t), or the open circuit voltage OCV of a lithium ion battery is equal to the subtraction of the negative potential from the positive potential. At the same time, because there is a corresponding relationship between the integral of the charging and discharging current I on the charging and discharging time t and the lithium ion migration amount, i.e., the amount of lithium intercalation or lithium deintercalation of the positive and negative electrodes, that is, a corresponding relationship exists with the charging capacity of the battery. Therefore, the battery charging capacity curve can be obtained by integrating the charge and discharge current I.
At step S400, calculating the charging capacity-open circuit voltage curve Q(Vocv) or the open circuit voltage-charging capacity curve Vocv(Q). Since both the open circuit voltage curve Vocv(t) and the charging capacity curve Q(t) are functions of time, the charging capacity-open circuit voltage curve Q(Vocv) or the open circuit voltage-charging capacity curve Vocv(Q) can be simply calculated.
At step S500, obtaining the third characteristic point (Vocv1, Q1) and the fourth characteristic point (Vocv2, Q2) on the curve Q(Vocv) or Vocv(Q).
Specifically, taking the curve Q(Vocv) as an example, the open circuit voltage Vocv(t)=Vp(t)−Vn(t), and the first characteristic curve Vp(x) has the first characteristic point (x1, Vp1), the second characteristic curve Vn(y) has the second characteristic point (y2, Vn2), and the amount of the lithium intercalation x of the to positive electrode and the amount of the lithium intercalation y of the negative electrode correspond to the battery charging capacity Q. Due to the specificity of the above characteristic points, the third characteristic point (Vocv1, Q1) corresponding to the first characteristic point (x1, Vp1), and the fourth characteristic point (Vocv2, Q2) corresponding to the second characteristic point is (y2, Vn2) can be determined on the curve Q(Vocv). When the state of the lithium ion battery is at the third characteristic point, the amount of the positive electrode lithium intercalation x is the amount of the positive electrode lithium intercalation x1 of the first characteristic point (x1, Vp1); when the state of the lithium ion battery is at the third characteristic point, the amount of the negative electrode lithium intercalation y is the amount of the negative electrode lithium intercalation y2 of the second characteristic point.
At step S600, calculating the amounts of the lithium intercalations of the positive and negative electrodes based on relationships of the characteristic points, the electrode lithium intercalations and the charging capacity: calculating a positive electrode full discharge lithium intercalation amount x0, a positive electrode full charge lithium intercalation amount x100%, a negative electrode full discharge lithium intercalation amount y0, and a negative electrode full charge lithium intercalation amount y100%, according to the data of the first characteristic point, the second characteristic point, the third characteristic point, and the fourth characteristic point.
In the charging and discharging process at a small current rate, changes in the lithium intercalations of the positive and negative electrodes can be considered to be same, therefore, the state of charge SOC of the battery, which is equivalent to the normalized battery charging capacity Q, can be calculated by the following formula:
where θ is the amount of the lithium intercalation in an electrode (positive or negative), θ0 is the amount of the lithium intercalation in the electrode when discharged to the discharging cutoff voltage, and θ100% is the amount of the lithium intercalation in the electrode when charged to the charging cutoff voltage.
Specifically, step S600 includes: solving the following equations to calculate the positive electrode full discharge lithium intercalation amount x0, the positive electrode full charge lithium intercalation amount x100%, the negative electrode full discharge lithium intercalation amount y0, and the negative electrode full charge lithium intercalation amount y100%:
wherein x2 is the positive electrode lithium intercalation amount obtained according to the first characteristic curve Vp(x) after a positive electrode potential Vp2=Vocv2+Vn2 corresponding to the fourth characteristic point is calculated, where Vocv2 is the battery open circuit voltage of the fourth characteristic point, and Vn2 is the negative electrode potential of the second characteristic point. y1 is the negative electrode lithium intercalation amount obtained according to the second characteristic curve Vn(y) after a negative electrode potential Vn1=Vp1−Vocv1 corresponding to the third characteristic point is calculated, where Vocv1 is the battery open circuit voltage of the third characteristic point, and Vp1 is the positive electrode potential of the first characteristic point. In some embodiments, the first characteristic point (x1, Vp1) is obtained through extremum points of a differential curve dVp(x)/dx of the first characteristic curve Vp(x). The second characteristic point (y2, Vn2) is obtained through extremum points of a differential curve dVn(y) dy of the second characteristic curve Vn(y). The third characteristic point (Vocv1, Q1) is obtained by comparing a differential curve of the curve Q(Vocv) with the differential curve dVp(x)/dx of the first characteristic curve Vp(x), or comparing a differential curve of the curve Vocv(Q) with the differential curve dVp(x)/dx of the first characteristic curve Vp(x). The fourth characteristic point (Vocv2, Q2) is obtained by comparing a differential curve of the curve Q(Vocv) with the differential curve dVn(y)/dy of the second characteristic curve Vn(y), or comparing a differential curve of the curve Vocv(Q) with the differential curve dVn(y)/dy of the second characteristic curve Vn(y).
Similarly, from the curve Vocv(t) shown in
In some embodiments, the small current rate charging and discharging is process includes a small current rate charging process and a small current rate discharging process; and the open circuit voltage curve Vocv(t) and the charging capacity curve Q(t) are obtained by averaging data obtained from at least one of the small current rate charging processes and at least one of the small current discharge processes.
Since the positive and negative electrode materials need to overcome the lithium intercalation potential or lithium deintercalation potential of the positive and negative electrode materials during the charging and discharging process, there will be charging and discharging overpotentials. Specifically, during the charging process, the actual measured terminal voltage of the battery at a certain moment will be slightly higher than the open circuit voltage of the battery at this time, while during the discharging process, the actually measured terminal voltage of the battery at a certain moment will be slightly lower than the open circuit voltage of the battery. In the process of charging and discharging at a small current rate, the above-mentioned overpotentials are very small and can be ignored. However, in order to further improve the measurement accuracy, or to reduce the strict requirements on the current of the charging and discharging process, a more accurate open circuit voltage curve Vocv(t) can be obtained by averaging the data obtained during one small current rate charging process and one small current discharging process. It should be noted that the reliability of the measured data can be further improved by averaging the data of multiple measurements.
In some embodiments, when the differential curve dVp(x)/dx of the first characteristic curve Vp(x) has multiple extremum points, the first characteristic point (x1, Vp1) is obtained according to one extremum point having the largest or smallest value; and when the differential curve dVn(y)/dy of the second characteristic curve Vn(y) has multiple extremum points, the second characteristic point (y2, Vn2) is obtained according to one extremum point having the largest or is smallest value. As shown in
In some embodiments, the charging and discharging current I adopted in the charging and discharging process with the small current rate is a constant current, and the charging and discharging rate is not greater than C/20. In addition to the constant current charging and discharging process, a staged constant current charging and discharging process can also be used, or a non-constant current charging and discharging process with little current fluctuation can be used. When using constant current charging and discharging, the process of obtaining the battery charging capacity curve Q(t) by integrating the charging and discharging current I in step S300 can be replaced by a simple calculation of Q(t)=I*t. In the embodiment shown in
In addition to obtaining the relationship curves between the battery charging capacity Q and the open circuit voltage OCV of the lithium ion battery through the charging and discharging process at a small current rate, i.e., the curve Q(Vocv) or Vocv(Q), HPPC (Hybrid Pulse Power Characterization) test can also be used to obtain the above relationship curves.
The following describes the specific calculation process of the lithium intercalation parameters of the positive and negative electrodes in the embodiments shown in
Further, the curve dQ/dV shown in
Further, according to the first characteristic curve and the second characteristic curve, the positive electrode potential Vp1 corresponding to the first characteristic point and the negative electrode potential Vn2 corresponding to the second characteristic point can be obtained.
V
p1
=V
p(x1)=3.908V;
V
n2
=V
n(y2)=0.196V;
Further, according to the battery open circuit voltage relational formula Vocv(t)=Vp(t)−Vn(t), the negative potential Vn1 corresponding to the first characteristic point and the positive potential Vp2 corresponding to the second characteristic point can be calculated:
V
n1
=V
p1
−V
ocv1=0.221V;
V
p2
=V
n2
+V
ocv2=3.914V;
Further, according to the negative electrode potential Vn1 corresponding to the first characteristic point and the positive electrode potential Vp2 corresponding to the second characteristic point obtained based on the first characteristic curve and the second characteristic curve in the previous step, the amount of the negative electrode lithium intercalation y1 corresponding to the first characteristic point and the amount of the positive electrode lithium intercalation x2 corresponding to the second characteristic point are obtained:
y
1
=y(Vn1)=0.351;
x
2
=x(Vp2)=0.793;
Further, the above numerical values are substituted into the following equations in step S600, namely,
to obtain:
Solving the above two binary linear equations, we can get the amount of the positive electrode discharge lithium intercalation x0, the amount of the positive is electrode full charge lithium intercalation x100%, the amount of the negative electrode discharge lithium intercalation y0, and the amount of the negative electrode full charge lithium intercalation y100%
In some embodiments, according to the positive electrode full discharge lithium intercalation amount x0, the positive electrode full charge lithium intercalation amount x100%, the negative electrode full discharge lithium intercalation amount y0, the negative electrode full charge lithium intercalation amount y100%, the ranges of the positive electrode lithium intercalation amount and the negative electrode insertion amount, the state of health of the electrodes of the lithium ion battery is determined. The capacity loss of the lithium ion battery is partly due to the side reaction between the electrode material and the organic electrolyte, which can usually be reflected in the lithium intercalation parameters of the positive and negative electrodes. By obtaining the lithium intercalation parameters of the positive and negative electrodes, combined with the electrochemical model, the state of health of electrodes of the lithium ion battery can be diagnosed.
In some embodiments, the first characteristic curve Vp(x) and the second characteristic curve Vn(y) are obtained through a half-cell test. The first characteristic curve and the second characteristic curve shown in
In some embodiments, the lithium ion battery is always placed in an environment with constant temperature and constant humidity during charging and discharging at a small current rate. The test temperature can adopt the set battery operating voltage of the common battery management system BMS, such as 45°, while controlling the humidity of the test environment within a lower range. Usually, the lithium ion battery can be placed in an environmental test chamber for relevant measurements, or the lithium ion battery can be connected to the battery management system BMS with a thermal management system for HiL real-time simulation testing.
In one aspect, the invention relates to an electronic device (apparatus) for detecting the lithium intercalation amounts of the electrodes of the lithium ion battery. The electronic device is configured to perform the non-destructive electrode detection of the lithium ion battery by using the method for detection of the lithium ion battery electrode lithium intercalation according to any of the foregoing embodiments. In one embodiment, the electronic device comprises a detection device (module) and a data processing device (module), wherein the detection device is used for realizing the small current charging and discharging cycles of the lithium ion battery and simultaneously measuring related data; the detection device can further comprise a calculation and analysis module for calculating and analyzing the electrode lithium intercalation parameters of the lithium ion battery according to the detection method disclosed above. The battery management system BMS can be connected for carrying out HiL real-time is simulation test on the lithium ion battery.
In another aspect, the invention relates to a battery management system. The battery management system BMS includes the lithium ion battery positive and negative electrode lithium intercalation detection device of the foregoing embodiment, has a small current rate charging function for performing non-destructive electrode detection on the lithium ion battery. The thermal management function of the battery management system BMS realizes the constant temperature and humidity ventilation management of the lithium ion battery. The battery management system BMS monitors and diagnoses the battery state through the electrochemical model and the detection results of the amount of lithium intercalated into the electrodes.
Table 1 lists the symbols and terms used in the specification and their physical meanings.
The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become to apparent to those skilled in the art to which the invention pertains without departing from its spirit and scope. Accordingly, the scope of the invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210587756.5 | May 2022 | CN | national |
