Charging method based on battery internal characteristics

Abstract

A charging method based on battery internal characteristics comprises the following steps: 1) establishing a corresponding battery mechanism model for calculating the internal characteristic value during the battery charging process according to the battery type and model, setting the safety upper limit threshold of the battery internal characteristic fast charging, the battery constant voltage charging threshold, and the fast charging current threshold; 2) obtaining a standard internal characteristic change curve when the battery is charged with a standard charging current at a constant current according to the battery mechanism model; 3) selecting a plurality of charging currents of different sizes to charge the battery at a constant current and obtaining the corresponding theoretical internal characteristic change curve; 4) selecting the overlapping part of the best theoretical internal characteristic change curve and the standard internal characteristic change curve as the fast charging internal characteristic change curve of the battery; 5) controlling the entire charging process of the battery according to the battery internal characteristic value at the current moment.

Description

Technical Field

[0001] The present invention relates to the field of battery charging strategies, and in particular to a charging method based on battery internal characteristics. Background Art

[0002] Pure electric vehicles (EVs) use lithium-ion batteries as their power source, and their development is also restricted by lithium battery-related technologies. Compared with the convenience of refueling traditional fuel vehicles, EVs battery charging time is too long, resulting in EVs always having range anxiety during driving, which to a certain extent restricts the further development of EVs. The main reason for limiting the increase of battery charging current is that when charging the battery with a large current, many side reactions will occur inside the battery, causing the battery capacity to decay rapidly and shorten its life. In severe cases, it may even cause the battery to explode, causing safety accidents.

[0003] Most of the widely used battery charging strategies are based on the changes in external characteristics that can be measured from the battery, such as the voltage, current, temperature, and power at the battery output end. They are formulated based on empiricism and do not delve into the internal mechanism of the battery. For example, the most widely used and simplest constant current constant voltage (CCCV) charging strategy divides the charging process into two stages: constant current and constant voltage. The switching condition is when the battery output voltage reaches a certain value. Charging strategies based on external characteristics are inevitably conservative to avoid safety accidents, and thus cannot accurately control the charging time according to the charging current. How to improve the charging efficiency of the battery while ensuring safety has always been an urgent problem to be solved in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a charging method based on battery internal characteristics in view of the corresponding deficiencies in the prior art, which uses the battery internal characteristics to measure the side reaction intensity of the battery, and increases the charging current within the side reaction intensity range allowed by the battery. While ensuring charging safety, the charging time of the lithium-ion battery is further shortened and the battery charging efficiency is improved.

[0005] The object of the present invention is to adopt the following scheme to achieve: a charging method based on the internal characteristics of the battery, comprising the following steps:

[0006] 1) According to the battery type and model, establish a corresponding battery mechanism model for calculating the internal characteristic value during the battery charging process, set the safety upper limit threshold of the battery internal characteristic fast charging, the battery constant voltage charging threshold, and the fast charging current threshold;

[0007] 2) According to the battery mechanism model, obtain the standard internal characteristic change curve when the battery is charged with constant current using the standard charging current;

[0008] 3) Selecting multiple charging currents of different sizes to perform constant current charging on the battery, and obtaining the corresponding theoretical internal characteristic change curve, the selected charging currents are all greater than the fast charging current threshold and less than the safety upper limit threshold, and the fast charging current threshold is greater than the standard charging current;

[0009] 4) Selecting the overlapped portion of the best theoretical internal characteristic change curve and the standard internal characteristic change curve as the fast charging internal characteristic change curve of the battery;

[0010] 5) During the charging process of the battery, the internal characteristic values ​​of the battery are calculated in real time according to the corresponding battery mechanism model, and the entire charging process of the battery is controlled in the following manner:

[0011] 5-1) If the current internal characteristic value of the battery is on the fast charging internal characteristic change curve, the fast charging current is used to perform constant current charging on the battery;

[0012] 5-2) If the current internal characteristic value of the battery is ≥ the maximum internal characteristic value on the fast charging internal characteristic change curve, the battery is charged with a constant current using a standard charging current;

[0013] 5-3) When the battery output voltage is ≥ the battery constant voltage charging threshold, the battery is charged at a constant voltage until the battery is fully charged.

[0014] Preferably, the theoretical internal characteristic change curve having the highest degree of coincidence with the standard internal characteristic change curve is selected as the best theoretical internal characteristic change curve.

[0015] Preferably, the battery mechanism model includes a SEI film growth side reaction kinetic equation, and the SEI film growth side reaction kinetic equation is as follows:

[0016]

[0017] In the formula, j SEI is the local current density of the side reaction rate, H is the dimensionless graphite expansion factor function, which is zero when lithium ions are deintercalated, and K is the expansion coefficient related to the local SOC of the electrode. loc is the local SOC, j is the local current density describing the main reaction rate, Ji 1C,loc is the local dimensionless exchange current density of the side reaction corresponding to the current intensity generated by the complete discharge of the battery in one hour, F is the Faraday constant, α is the charge transfer coefficient, f is the lumped dimensionless parameter based on the characteristics of the SEI film, η SEI To consider the overpotential of the side reaction of SEI film growth, J is the dimensionless exchange current density of the side reaction, qSEI is the local accumulated charge due to SEI formation, R is the gas constant, T is the battery temperature, i 1C,loc It is the local current density corresponding to the current intensity generated by the complete discharge of the battery in one hour.

[0018] Preferably, the battery mechanism model includes a solid phase material conservation equation, and the solid phase material conservation equation is as follows:

[0019]

[0020] In the formula, c s (x, r, t) is the concentration of lithium ions at position x at time t at radial position r inside the electrode active particle, r is the radial direction of the active particle, D s is the diffusion coefficient of lithium in the solid phase.

[0021] Preferably, the battery mechanism model includes a solid phase charge conservation equation, which is as follows:

[0022]

[0023] In the formula, i s (x,t) is the current density in the solid phase at position x at time t, φ s (x,t) is the potential in the solid phase at position x at time t, is the effective electronic conductivity in the solid phase material, j f (x, t) is the local electric fluid density at the solid-liquid interface at position x at time t.

[0024] Preferably, the battery mechanism model includes a liquid phase substance conservation equation, and the liquid phase substance conservation equation is as follows:

[0025]

[0026] In the formula, c e (x, t) is the concentration of lithium ions in the liquid phase at position x at time t, ε e is the electrolyte volume fraction, is the migration number of lithium ions, a s is the specific surface area of ​​the solid particles, is the effective diffusion coefficient of the electrolyte, j(x,t) is the local current density on the surface of the electrode particle at position x at time t, and F is the Faraday constant.

[0027] Preferably, the battery mechanism model includes a liquid phase charge conservation equation, which is as follows:

[0028]

[0029] In the formula, i e (x, t) is the current density in the liquid phase at position x at time t, c e (x,t) is the concentration of lithium ions in the liquid phase at position x at time t, φ e (x,t) is the potential in the electrolyte at position x at time t, is the effective ionic conductivity of the electrolyte, is the effective diffusion conductivity of the electrolyte, j f (x, t) is the local current fluid density at the solid-liquid interface at position x at time t.

[0030] Preferably, the battery mechanism model includes the Buter-Volmer electrode kinetic equation, and the Buter-Volmer electrode kinetic equation is as follows:

[0031]

[0032]

[0033]

[0034] Where j(x,t) is the local current density on the surface of the electrode particle at position x at time t, i0 is the exchange current density, F is the Faraday constant, and α a is the anode charge transfer coefficient, α c is the cathode charge transfer coefficient; R is the gas constant, T is the battery temperature, η(x,t) is the local surface overpotential, c s,surf is the lithium concentration on the surface of the active material, c s,max is the maximum lithium concentration in the electrode, k0 is the electrochemical reaction rate constant, c e is the concentration of lithium ions in the liquid phase, φ s (x,t) is the potential in the solid phase at position x at time t, φ e (x, t) is the potential in the electrolyte at position x at time t, R SEI is the membrane resistance of the SEI film, is the equilibrium potential of the electrode, θ j (x,t) is the position c at time t s,surf With c s,max ratio.

[0035] Preferably, the battery mechanism model includes a calculation formula for the battery input terminal current, and the calculation formula for the battery input terminal current is as follows:

[0036]

[0037] In the formula, I app(t) is the battery input current at time t, A cell is the surface area of ​​the battery electrode, i s (x,t) is the current density in the solid phase at position x at time t, i e (x, t) is the current density in the liquid phase at position x at time t.

[0038] Preferably, the battery mechanism model includes a calculation formula for the battery output terminal voltage, and the calculation formula for the battery output terminal voltage is as follows:

[0039] U t (t) = φ s (x,t)| x＝L -φ s (x,t)| x＝0 -I app (t)·R ext

[0040] Where U t (t) is the battery output voltage at time t, φ s (x,t)| x＝L is the solid phase potential of the positive electrode current collector at time t, φ s (x,t)| x＝0 is the solid phase potential of the negative electrode current collector at time t, I app (t) is the battery input current at time t, R ext The additional ohmic resistance formed by the connection resistance and the internal resistance of the current collector.

[0041] The advantages of the present invention are that the internal characteristic values ​​of the battery during the charging process can be calculated in real time through the SEI film growth side reaction kinetic equation of the battery mechanism model, the side reaction intensity can be monitored, and the charging current can be increased within the side reaction intensity range allowed by the battery. While ensuring charging safety, the charging time of the lithium-ion battery can be further shortened and the battery charging efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0043] like Figure 1 As shown, a charging method based on the internal characteristics of a battery comprises the following steps:

[0044] 1) According to the battery type and model, establish a corresponding battery mechanism model in the simulation software for calculating the internal characteristic value during the battery charging process, set the safety upper limit threshold of the battery internal characteristic fast charging, the battery constant voltage charging threshold, and the fast charging current threshold;

[0045] In this embodiment, the safety upper limit threshold, the battery constant voltage charging threshold, and the fast charging current threshold are all empirical values.

[0046] The fast charging current threshold is the minimum charging current when the battery is charged with a constant current based on its internal characteristics, that is, the charging current must be at least greater than the fast charging current threshold. If it is less than or equal to the fast charging current threshold, the charging time will be too long and the charging efficiency of the battery cannot be improved.

[0047] The safety upper limit threshold of the fast charging of the battery's internal characteristic is the maximum internal characteristic value that meets the safety requirements during the battery's charging process. Once the internal characteristic value of the battery during the charging process exceeds the safety upper limit threshold, the battery capacity will decay rapidly and its life will be shortened. In severe cases, it may even cause the battery to explode, resulting in a safety accident. Therefore, during the charging process, it is necessary to ensure that the real-time internal characteristic value is not greater than the safety upper limit threshold at any time. In this embodiment, the side reaction corresponding to the internal characteristic is the SEI film growth side reaction.

[0048] The battery constant voltage charging threshold is the maximum allowable voltage at the battery output terminal during the constant current charging process. Once the battery output terminal voltage exceeds the battery constant voltage charging threshold, it must be switched to constant voltage charging immediately, otherwise the battery voltage will continue to rise, internal polarization will occur, until the battery structure is damaged, the battery fails or even explodes.

[0049] In this embodiment, the battery mechanism model includes not only the solid phase material conservation equation, the solid phase charge conservation equation, the liquid phase material conservation equation, the liquid phase charge conservation equation, the Butler-Volmer electrode kinetic equation, and the calculation formulas for the battery input terminal current and the battery output terminal voltage, but also the SEI film growth side reaction kinetic equation, which is used to determine the degree of battery capacity attenuation caused by the SEI film generation side reaction.

[0050] ① The SEI film growth side reaction kinetic equation is as follows:

[0051]

[0052] In the formula, j SEI is the local current density of the side reaction rate, H is the dimensionless graphite expansion factor function, which is zero when lithium ions are deintercalated, and K is the expansion coefficient related to the local SOC of the electrode. loc is the local SOC, j is the local current density describing the main reaction rate, Ji 1C,loc is the local dimensionless exchange current density of the side reaction corresponding to the current intensity generated by the complete discharge of the battery in one hour, F is the Faraday constant, α is the charge transfer coefficient, f is the lumped dimensionless parameter based on the characteristics of the SEI film, η SEITo consider the overpotential of the side reaction of SEI film growth, J is the dimensionless exchange current density of the side reaction, q SEI is the local accumulated charge due to SEI formation, R is the gas constant, T is the battery temperature, i 1C,loc It is the local current density corresponding to the current intensity generated by the complete discharge of the battery in one hour.

[0053] ②The solid phase material conservation equation is as follows:

[0054]

[0055] In the formula, c s (x, r, t) is the concentration of lithium ions at position x at time t at radial position r inside the electrode active particle, r is the radial direction of the active particle, D s is the diffusion coefficient of lithium in the solid phase.

[0056] ③The solid phase charge conservation equation is as follows:

[0057]

[0058] In the formula, i s (x,t) is the current density in the solid phase at position x at time t, φ s (x,t) is the potential in the solid phase at position x at time t, is the effective electronic conductivity in the solid phase material, j f (x, t) is the local electric fluid density at the solid-liquid interface at position x at time t.

[0059] ④The liquid phase substance conservation equation is as follows:

[0060]

[0061] In the formula, c e (x, t) is the concentration of lithium ions in the liquid phase at position x at time t, ε e is the electrolyte volume fraction, is the migration number of lithium ions, a s is the specific surface area of ​​the solid particles, is the effective diffusion coefficient of the electrolyte, j(x,t) is the local current density on the surface of the electrode particle at position x at time t, and F is the Faraday constant.

[0062] ⑤The liquid phase charge conservation equation is as follows:

[0063]

[0064] In the formula, i e (x, t) is the current density in the liquid phase at position x at time t, ce (x,t) is the concentration of lithium ions in the liquid phase at position x at time t, φ e (x,t) is the potential in the electrolyte at position x at time t, is the effective ionic conductivity of the electrolyte, is the effective diffusion conductivity of the electrolyte, j f (x, t) is the local current fluid density at the solid-liquid interface at position x at time t.

[0065] ⑥ The Butler-Volmer electrode kinetic equation is as follows:

[0066]

[0067]

[0068]

[0069] Where j(x,t) is the local current density on the surface of the electrode particle at position x at time t, i0 is the exchange current density, F is the Faraday constant, and α a is the anode charge transfer coefficient, α c is the cathode charge transfer coefficient; R is the gas constant, T is the battery temperature, η(x,t) is the local surface overpotential, c s,surf is the lithium concentration on the surface of the active material, c s,max is the maximum lithium concentration in the electrode, k0 is the electrochemical reaction rate constant, c e is the concentration of lithium ions in the liquid phase, φ s (x,t) is the potential in the solid phase at position x at time t, φ e (x, t) is the potential in the electrolyte at position x at time t, R SEI is the membrane resistance of the SEI film, is the equilibrium potential of the electrode, θ j (x,t) is the position c at time t s,surf With c s,max ratio.

[0070] ⑦The calculation formula of the battery input current is as follows:

[0071]

[0072] In the formula, I app (t) is the battery input current at time t, A cell is the surface area of ​​the battery electrode, i s (x,t) is the current density in the solid phase at position x at time t, i e (x, t) is the current density in the liquid phase at position x at time t.

[0073] ⑧The calculation formula of the battery output terminal voltage is as follows:

[0074] U t (t) = φ s (x,t)| x＝L -φ s (x,t)| x＝0 -I app (t)·R ext

[0075] Where U t (t) is the battery output voltage at time t, φ s (x,t)| x＝L is the solid phase potential of the positive electrode current collector at time t, φ s (x,t)| x＝0 is the solid phase potential of the negative electrode current collector at time t, I app (t) is the battery input current at time t, R ext The additional ohmic resistance formed by the connection resistance and the internal resistance of the current collector.

[0076] 2) According to the battery mechanism model, a standard internal characteristic change curve when the battery is charged at a constant current using a standard charging current is obtained, where the standard charging current is an empirical value obtained by the battery manufacturer through a calibration experiment.

[0077] 3) Selecting multiple charging currents of different sizes to perform constant current charging on the battery, and obtaining the corresponding theoretical internal characteristic change curve, the selected charging currents are all greater than the fast charging current threshold and less than the safety upper limit threshold, and the fast charging current threshold is greater than the standard charging current;

[0078] The standard internal characteristic change curve and the theoretical internal characteristic change curve are both curves that reflect the internal characteristics of the lithium battery during the charging process. The internal characteristics are the internal characteristics of the battery that cannot be obtained by direct measurement, such as lithium ion concentration and overpotential, but can only be calculated by the battery mechanism model. Side reactions such as lithium precipitation reaction, decomposition of positive and negative electrode materials, decomposition of electrolyte, irreversible reaction caused by impurities in the electrolyte, shedding of positive and negative electrode materials, blockage or damage of isolation membranes, etc., all have corresponding internal characteristic curves.

[0079] In the present embodiment, since the SEI film growth side reaction kinetic equation is used to reflect the battery capacity attenuation degree caused by the SEI film generation side reaction, that is, the side reactions corresponding to the standard internal characteristic change curve and the theoretical internal characteristic change curve are all SEI film growth side reactions, if other side reactions need to be referred to according to demand, it is only necessary to add the corresponding internal characteristic calculation formula to the corresponding battery mechanism model.

[0080] 4) Selecting the overlapped portion of the best theoretical internal characteristic change curve and the standard internal characteristic change curve as the fast charging internal characteristic change curve of the battery;

[0081] In this embodiment, the theoretical internal characteristic change curve with the highest degree of coincidence with the standard internal characteristic change curve is selected as the best theoretical internal characteristic change curve.

[0082] Each internal characteristic variation curve is a monotonically increasing curve set in a plane rectangular coordinate system, the horizontal axis of the plane rectangular coordinate system is time, and the vertical axis is the internal characteristic value. The coincidence degree can be determined by the following method:

[0083] (1) Setting the overlap threshold interval;

[0084] (2) Calculate the difference between the ordinates of each point on the two curves. When the difference is within the overlap threshold interval, the two curves overlap at this point, and this point is the overlap point of the two curves.

[0085] (3) The more overlapping points there are, the higher the degree of overlap between the two curves.

[0086] 5) The battery mechanism model and its various parameter values ​​are written into the battery management system BMS. During the charging process of the battery, the battery internal characteristic values ​​are calculated in real time according to the corresponding battery mechanism model, and the entire charging process of the battery is controlled in the following manner:

[0087] 5-1) If the battery internal characteristic value at the current moment is on the fast charging internal characteristic change curve, the fast charging current is used to charge the battery at a constant current, that is, when the coordinates composed of the time value at the current moment and the corresponding battery internal characteristic value coincide with the coordinate point corresponding to the current moment on the fast charging internal characteristic change curve, the fast charging current is used to charge the battery at a constant current;

[0088] 5-2) If the current internal characteristic value of the battery is ≥ the maximum internal characteristic value on the fast charging internal characteristic change curve, the battery is charged with a constant current using a standard charging current;

[0089] 5-3) When the battery output voltage is ≥ the battery constant voltage charging threshold, the battery is charged at a constant voltage until the battery is fully charged.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A charging method based on battery internal characteristics, characterized in that: The following steps are involved: 1) According to the battery type and model, establish a corresponding battery mechanism model for calculating the internal characteristic value during the battery charging process, set the safety upper limit threshold of the battery internal characteristic fast charging, the battery constant voltage charging threshold, and the fast charging current threshold; 2) According to the battery mechanism model, obtain the standard internal characteristic change curve when the battery is charged with constant current using the standard charging current; 3) Selecting multiple charging currents of different sizes to perform constant current charging on the battery, and obtaining the corresponding theoretical internal characteristic change curve, the selected charging currents are all greater than the fast charging current threshold and less than the safety upper limit threshold, and the fast charging current threshold is greater than the standard charging current; 4) Selecting the overlapped portion of the best theoretical internal characteristic change curve and the standard internal characteristic change curve as the fast charging internal characteristic change curve of the battery; 5) During the charging process of the battery, the internal characteristic values ​​of the battery are calculated in real time according to the corresponding battery mechanism model, and the entire charging process of the battery is controlled in the following manner: 5-1) If the current internal characteristic value of the battery is on the fast charging internal characteristic change curve, the fast charging current is used to perform constant current charging on the battery; 5-2) If the current internal characteristic value of the battery is ≥ the maximum internal characteristic value on the fast charging internal characteristic change curve, the battery is charged with a constant current using a standard charging current; 5-3) When the battery output voltage is ≥ the battery constant voltage charging threshold, the battery is charged at a constant voltage until the battery is fully charged.

2. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The theoretical internal characteristic change curve with the highest degree of coincidence with the standard internal characteristic change curve is selected as the best theoretical internal characteristic change curve.

3. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a SEI film growth side reaction kinetic equation, and the SEI film growth side reaction kinetic equation is as follows: In the formula, j SEI is the local current density of the side reaction rate, H is the dimensionless graphite expansion factor function, which is zero when lithium ions are deintercalated, and K is the expansion coefficient related to the local SOC of the electrode. loc is the local SOC, j is the local current density describing the main reaction rate, Ji 1C,loc is the local dimensionless exchange current density of the side reaction corresponding to the current intensity generated by the complete discharge of the battery in one hour, F is the Faraday constant, α is the charge transfer coefficient, f is the lumped dimensionless parameter based on the characteristics of the SEI film, η SEI To consider the overpotential of the side reaction of SEI film growth, J is the dimensionless exchange current density of the side reaction, q SEI is the local accumulated charge due to SEI formation, R is the gas constant, T is the battery temperature, i 1C,loc It is the local current density corresponding to the current intensity generated by the complete discharge of the battery in one hour.

4. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a solid phase material conservation equation, which is as follows: In the formula, c s (x, r, t) is the concentration of lithium ions at position x at time t at radial position r inside the electrode active particle, r is the radial direction of the active particle, D s is the diffusion coefficient of lithium in the solid phase.

5. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a solid phase charge conservation equation, which is as follows: In the formula, i s (x,t) is the current density in the solid phase at position x at time t, φ s (x,t) is the potential in the solid phase at position x at time t, is the effective electronic conductivity in the solid phase material, j f (x, t) is the local electric fluid density at the solid-liquid interface at position x at time t.

6. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a liquid phase material conservation equation, which is as follows: In the formula, c e (x, t) is the concentration of lithium ions in the liquid phase at position x at time t, ε e is the electrolyte volume fraction, is the migration number of lithium ions, a s is the specific surface area of ​​the solid particles, is the effective diffusion coefficient of the electrolyte, j(x,t) is the local current density on the surface of the electrode particle at position x at time t, and F is the Faraday constant.

7. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a liquid phase charge conservation equation, which is as follows: In the formula, i e (x, t) is the current density in the liquid phase at position x at time t, c e (x,t) is the concentration of lithium ions in the liquid phase at position x at time t, φ e (x,t) is the potential in the electrolyte at position x at time t, is the effective ionic conductivity of the electrolyte, is the effective diffusion conductivity of the electrolyte, j f (x, t) is the local current fluid density at the solid-liquid interface at position x at time t.

8. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes the Butler-Volmer electrode kinetic equation, which is as follows: Where j(x,t) is the local current density on the surface of the electrode particle at position x at time t, i0 is the exchange current density, F is the Faraday constant, and α a is the anode charge transfer coefficient, α c is the cathode charge transfer coefficient; R is the gas constant, T is the battery temperature, η(x,t) is the local surface overpotential, c s,surf is the lithium concentration on the surface of the active material, c s,max is the maximum lithium concentration in the electrode, k0 is the electrochemical reaction rate constant, c e is the concentration of lithium ions in the liquid phase, φ s (x,t) is the potential in the solid phase at position x at time t, φ e (x, t) is the potential in the electrolyte at position x at time t, R SEI is the membrane resistance of the SEI film, is the equilibrium potential of the electrode, θ j (x,t) is the position c at time t s,surf With c s,max ratio.

9. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a calculation formula for the battery input terminal current, and the calculation formula for the battery input terminal current is as follows: In the formula, I app (t) is the battery input current at time t, A cell is the surface area of ​​the battery electrode, i s (x,t) is the current density in the solid phase at position x at time t, i e (x, t) is the current density in the liquid phase at position x at time t.

10. The charging method based on the internal characteristics of the battery according to claim 1, characterized in that: The battery mechanism model includes a calculation formula for the battery output terminal voltage, and the calculation formula for the battery output terminal voltage is as follows: U t (t)=φ s (x,t)| x＝L -φ s (x,t)| x＝0 -I app (t)·R ext Where U t (t) is the battery output voltage at time t, φ s (x,t)| x＝L is the solid phase potential of the positive electrode current collector at time t, φ s (x,t)| x＝0 is the solid phase potential of the negative electrode current collector at time t, I app (t) is the battery input current at time t, R ext The additional ohmic resistance formed by the connection resistance and the internal resistance of the current collector.

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