CN116910972A

CN116910972A - Electrode structure optimization method

Info

Publication number: CN116910972A
Application number: CN202310627727.1A
Authority: CN
Inventors: 张海燕; 常增花; 钱义; 姜景栋; 兰琪瑜; 刘星阁; 李翔; 王建涛
Original assignee: China Automotive Battery Research Institute Co Ltd
Current assignee: China Automotive Battery Research Institute Co Ltd
Priority date: 2023-05-30
Filing date: 2023-05-30
Publication date: 2023-10-20

Abstract

The application discloses an electrode structure optimization method, which comprises the following steps: constructing an electrochemical-thermal coupling model of the prototype battery based on material characteristic parameters, electrode structure parameters, battery design parameters and battery heat conduction parameters of the prototype battery; testing a prototype battery under different working conditions, simulating the performance of the prototype battery under the same working conditions based on the model, comparing a simulation test result with an actual test result, and correcting model parameters of the electrochemical-thermal coupling model based on the comparison result; and optimizing the electrode structure parameters in the corrected model by taking the battery energy density, the battery core thickness and the maximum lithium current as optimization targets to obtain the electrode structure optimization parameters of the prototype battery. According to the method and the device provided by the application, the battery model parameters and the battery design parameters are effectively associated, so that the simulation result has a practical reference meaning.

Description

Electrode structure optimization method

Technical Field

The application relates to the technical field of batteries, in particular to an electrode structure optimization method.

Background

With the development of lithium ion battery technology, the requirements of battery performance, such as higher energy density and faster charging power, are increasing. Increasing the electrode thickness or decreasing the electrode porosity by compaction is the most common method of increasing the energy density of the cell, but both methods increase the transmission resistance in the direction of the electrode thickness. At present, attempts are made to improve the thickness liquid phase transmission capacity of the gradient electrode by preparing the gradient electrode, but when the conventional experimental method is adopted to design the battery electrode, time and effort are consumed, influence of experimental errors or imported incoherent factors such as interlayer interface membrane resistance and the like is difficult to avoid, and judgment of electrode optimization rules is interfered. And the electrochemical model is adopted to carry out structural design optimization on the electrode, so that experimental design (Design of Experiment, DOE) can be independently carried out, and a clearer design direction is obtained. However, the current electrochemical model does not consider the influence of the electrode design parameter change on the thickness of the battery core and the influence of the electrode design parameter change on the lithium separation safety behavior of the cathode, and the model parameter and the battery design parameter are not effectively related, so that the guiding significance of the model optimization result on the battery design is not great, and therefore, how to effectively connect the model parameter and the battery design parameter is established, and the electrode structure parameter is screened by a more reasonable optimization target, so that the research and development processes of a high specific energy battery and a high power battery are guided and accelerated, and the technical problem to be solved in the industry is urgent.

Disclosure of Invention

The application provides an electrode structure optimization method which is used for solving the technical problems of how to establish effective connection between model parameters and battery design parameters in the prior art and screening electrode structure parameters by a more reasonable optimization target so as to guide and accelerate the research and development processes of high-specific-energy batteries and high-power batteries.

The application provides an electrode structure optimization method, which comprises the following steps:

constructing an electrochemical-thermal coupling model based on a prototype battery based on material characteristic parameters, electrode structure parameters, battery design parameters and battery heat conduction parameters of the prototype battery;

testing the prototype battery under different working conditions, and simulating the performance of the prototype battery under the same working condition based on the model;

comparing the simulation test result with the actual test result, and correcting model parameters of the electrochemical-thermal coupling model based on the comparison result;

and optimizing the electrode structure parameters in the corrected model by taking the battery energy density, the battery core thickness and the maximum lithium current as optimization targets to obtain the electrode structure optimization parameters of the prototype battery.

In some embodiments, the optimizing the electrode structure parameters in the corrected model by using the battery energy density, the cell thickness and the maximum lithium current as optimization targets to obtain the electrode structure optimization parameters of the prototype battery includes:

Taking one or more groups of electrode structure parameters as variables, performing DOE design on at least one electrode of the anode and the cathode, and obtaining a plurality of design schemes corresponding to the electrode structure parameters; the electrode structure parameters comprise surface density, porosity, main material occupation ratio and tortuosity;

calculating the energy density, the thickness of the battery core and the maximum lithium current without precipitation of the battery under different design schemes;

and comparing the calculation result with the optimization target, and optimizing each group of electrode structure parameters.

In some embodiments, the method for calculating the battery energy density comprises:

integrating voltage, current and time during charging or discharging of battery to obtain battery energy W _Batt The method comprises the steps of carrying out a first treatment on the surface of the Summing the mass of each component in the battery to obtain the theoretical mass M of the battery _Batt Thereby obtaining the theoretical energy density E of the battery _Batt The method comprises the steps of carrying out a first treatment on the surface of the The obtained theoretical energy density and target energy density E of the battery _aim Alignment is carried out by E _Batt >E _aim Optimizing electrode structure parameters for screening conditions;

the specific calculation formula is as follows:

theoretical energy density of cell E _Batt For battery energy W in the process of charging and discharging the battery _Batt Divided by the theoretical mass M of the battery _Batt ：

Battery energy W _Batt From operating current I and operating voltage E during operation _cell And the product of (2) is obtained by integrating the charge and discharge time t:

Theoretical mass of cell M _Batt From the mass m of the positive electrode _pos Mass m of negative electrode _neg Diaphragm mass m _sep Mass m of positive current collector _Al Mass m of negative electrode current collector _Cu And (3) adding and obtaining:

M _Batt ＝m _pos +m _neg +m _sep +m _ele +m _Al +m _Cu

battery capacity Q _cell From the maximum lithium ion concentration cs_pos_max of the positive electrode material and the volume fraction epsilon of the positive electrode material _{s_pos} Thickness L of positive electrode _pos Total electrode area A _cell And (3) obtaining an SOC interval:

Q _cell ＝cs_pos_max*ε _{s_pos} *L _pos *F _const *(SOC _{max_pos} -SOC _{min_pos} )*A _cell

m _pos ＝Q _cell /Y/C _pos

m _neg ＝Q _cell /X/C _neg

m _ele ＝(ε _{l_pos} *L _pos +ε _{l_neg} *L _neg +ε _{l_sep} *L _sep )*ρ _ele *A _cell

m _Al ＝L _Al *ρ _Al *A _cell /2

m _Cu ＝L _Cu *ρ _Cu *A _cell /2

wherein ε _{l_pos} Is the volume fraction of pores in the positive electrode; f (F) _const Is Faraday constant; SOC (State of Charge) _{max_pos} The lithium is maximally intercalated into the anode; SOC (State of Charge) _{min_pos} The lithium is embedded into the positive electrode at minimum; y is the first efficiency of the battery; x is the proportion of the cathode capacity to the excess cathode capacity; x=q _neg /Q _pos ；Q _neg Is the capacity of the cathode material; q (Q) _pos Is the capacity of the positive electrode material; m is m _ele The electrolyte is of the mass; c (C) _pos The mass specific capacity of the positive electrode material; c (C) _neg The mass specific capacity of the cathode material; epsilon _{l_neg} A volume fraction of pores in the negative electrode; epsilon _{l_sep} Is the volume fraction of pores in the separator; l (L) _neg The thickness of the cathode electrode; l (L) _sep Is the thickness of the diaphragm; l (L) _Al The thickness of the positive electrode current collector is; l (L) _Cu Is the thickness of the negative current collector; ρ _ele Is the density of the electrolyte; ρ _Al Is the density of the positive current collector; ρ _Cu Is the density of the negative electrode current collector.

In some embodiments, the method for calculating the thickness of the battery includes:

adding the thicknesses of all the components in the battery; theoretical thickness L of cell _batt And the target cell thickness L _aim Alignment is carried out by L _batt <L _aim In order to screen the conditions, the electrode structure design parameters are optimized, and the specific calculation formula is as follows:

L _batt ＝L _pos *N _pos *2+L _neg *N _neg *2+L _sep *N _neg *2+L _Al *N _pos +L _Cu *N _neg

N _pos ＝A _cell /A _pos /2

N _neg ＝N _pos +1

wherein A is _pos Design parameters for the area of the monolithic electrode; a is that _cell The total area of a single-sided electrode in the lithium ion battery simulated by the model is calculated; l (L) _aim The thickness of the battery cell is the target thickness; n (N) _pos For the number of positive electrode lamination layers, N _neg Is the number of the stacked layers of the negative electrode.

In some embodiments, the method for obtaining the maximum battery current without lithium analysis includes setting a domain probe on the negative electrode, and extracting the minimum voltage U of the negative electrode of the battery in the charging process of different multiplying powers _{neg_min} In U form _{neg_min} The maximum charging current at greater than 0V is the maximum no-lithium-evolution current.

In some embodiments, the performing model parameter correction on the electrochemical-thermal coupling model includes:

testing and determining the performance of the prototype battery under different working conditions, including one or more than two of the following working conditions:

testing charging voltage-capacity curves of the prototype battery at the same current and different temperatures;

testing charging voltage-capacity curves of the prototype battery under the same temperature and different multiplying power currents;

testing discharge voltage-capacity curves of the prototype battery at the same current and different temperatures;

Testing discharge voltage-capacity curves of the prototype battery under the same temperature and different multiplying power currents;

testing the voltage-capacity curve of the prototype battery under the same temperature and different currents;

and determining a negative electrode potential-capacity curve of the prototype cell at different temperatures or different currents;

based on the model, the battery performance is simulated by adopting the same working condition as the prototype battery, and the battery performance is compared with the actual measurement result to correct the model parameters.

In some embodiments, the prototype cell comprises: the negative electrode current collector, the negative electrode, the diaphragm, the positive electrode and the positive electrode current collector;

wherein the negative electrode and/or the positive electrode has one or more layers of structures;

when the electrode is of a multilayer composite structure, the calculation method of the equation related to the thickness and the pore of the electrode is further refined, and the specific equation is as follows:

battery capacity Q _cell Adding the capacities of the positive electrode materials in the positive electrode:

Q _cell ＝Q _pos1 +Q _pos2 +…+Q _posn

Q _pos1 ＝cs_pos1_max*ε _{s_pos1} *L _pos1 *F _const *(SOC _{max_pos} -SOC _{min_pos} )*A _cell

Q _pos2 ＝cs_pos2_max*ε _{s_pos2} *L _pos2 *F _const *(SOC _{max_pos} -SOC _{min_pos} )*A _cell

Q _posn ＝cs_posn_max*ε _{s_posn} *L _posn *F _const *ε(SOC _{max_pos} -SOC _{min_pos} )*A _cell

electrolyte mass m _ele From mass m of electrolyte in the anode _{ele_neg} Electrolyte mass m in separator _{ele_sep} Mass of electrolyte in positive electrode +m _{ele_pos} Is added up; the mass of electrolyte in each section is the mass of electrolyte in the pores of each section: m is m _ele ＝m _{ele_neg} +m _{ele_sep} +m _{ele_pos}

Electrolyte mass m in negative electrode _{ele_neg} ：m _{ele_neg} ＝(ε _{l_neg1} *L _neg1 +ε _{l_neg2} *L _neg2 +...+ε _{l_negn} *L _negn )*ρ _ele *A _cell

Electrolyte mass m in separator _{ele_sep} ：

Electrolyte mass m in positive electrode _{ele_pos} ：m _{ele_pos} ＝(ε _{l_pos1} *L _pos1 +ε _{l_pos2} *L _pos2 +...+ε _{l_posn} *L _posn )*ρ _ele *A _cell

L _pos ＝L _pos1 +L _pos2 +...+L _posn

L _neg ＝L _neg1 +L _neg2 +...+L _negn

Wherein porosity is an electrode design parameter related to electrode packing density and formulation, and 1, 2 and n in the suffix of each letter represent the 1 st, 2 nd and n th layers of the positive or negative electrode.

In some embodiments, the method targeting battery energy density, cell thickness, and maximum no-lithium current, comprises:

designing DOE experiments and outputting different electrode structure parameters as variable groups;

inputting each group of electrode structure parameters into the model, and simulating the battery performance to obtain E _Batt 、L _batt And I _rate Comparing the obtained theoretical performance with the optimized target parameters, and screening the structural parameters of each group of electrodes by taking one or more conditions as limiting factors, wherein the method comprises the following steps:

E _Batt >E _aim and L is _batt <L _aim And I _rate @25℃>2C；

Or E is _Batt >E _aim And L is _batt <L _aim ；

Or L _batt <L _aim And I _rate @25℃>5C；

Or E is _Batt >E _aim And I _rate @25℃>2C；

I _rate Multiplying power current I at 25 ℃ at 25 DEG C _rate The method comprises the steps of carrying out a first treatment on the surface of the 1C is 1 hour of electricity used for dischargingStreams, i.e. 1c=q _cell /3600 seconds.

In some embodiments, the material characteristic parameters mainly comprise particle size of the anode and cathode materials, particle open circuit voltage curve, entropy coefficient, solid phase diffusion coefficient, exchange current density, reaction rate constant, maximum lithium ion density, reaction interval; at least one of thickness, density, porosity, density of electrolyte, liquid phase diffusion coefficient, and conductivity of the separator;

The electrode structure parameters comprise at least one of thickness of a positive electrode and a negative electrode, active material volume ratio, porosity, conductivity and tortuosity;

the battery design parameters comprise at least one of cell size, tab position and size and battery specific surface area;

the battery heat conduction parameter comprises at least one of a cell thickness direction heat transfer coefficient and a cell plane direction heat transfer coefficient.

In some embodiments, the electrochemical-thermal coupling model comprises a three-dimensional heat transfer model:

the three-dimensional heat transfer model is built based on the actual size of the prototype battery, and the thickness of the battery in the three-dimensional heat transfer model is changed along with the change of the electrode structure parameters;

the battery heat conduction parameters in all directions in the three-dimensional heat transfer model are determined based on the normalization processing results of the component ratios of the prototype battery;

and the heat exchange condition of the three-dimensional heat transfer is related to the actual working condition of the prototype battery.

According to the electrode structure optimization method provided by the application, an electrochemical-thermal coupling model based on the prototype battery can be constructed through the material characteristic parameters, the electrode structure parameters, the battery design parameters and the battery thermal conduction parameters of the prototype battery; the electrode structure parameters in the corrected model are optimized by taking the battery energy density, the battery core thickness and the maximum non-lithium-precipitation current as optimization targets, the influence of the electrode structure parameters on the battery core thickness and the battery energy density is considered, the lithium precipitation safety of the negative electrode in the fast charging process of the high specific energy battery is considered, and more accurate and high-feasibility electrode structure optimization parameters can be obtained, so that the electrode structure parameters are comprehensively optimized, the high specific energy, high power and high safety lithium ion battery is obtained, the comprehensive performance of the battery is improved, and the simulation result has more practical reference significance by effectively correlating the battery model parameters with the battery design parameters.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

In order to more clearly illustrate the application or the technical solutions of the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the application, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic flow chart of an electrode structure optimization method according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a two-dimensional structure of a prototype cell according to an embodiment of the present application;

FIG. 3 is a schematic diagram showing a two-dimensional structure of a prototype cell according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a three-dimensional structure of a prototype cell according to an embodiment of the present application;

FIG. 5 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application;

FIG. 6 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application;

FIG. 7 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a two-dimensional structure of a prototype cell according to an embodiment of the present application;

fig. 9 is a schematic three-dimensional structure of a prototype cell according to an embodiment of the present application;

FIG. 10 is a graph of a simulation test of a second simulation example of the present application;

FIG. 11 is a graph of a simulation test of simulation example III of the present application;

FIG. 12 is a graph of a simulation test of a fourth simulation example of the present application;

FIG. 13 is a schematic view of an electrode structure optimizing apparatus according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.

It should be noted that the terms "first," "second," and the like herein are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules that are expressly listed or inherent to such process, method, article, or apparatus.

Fig. 1 is a schematic flow chart of an electrode structure optimization method according to an embodiment of the present application, and as shown in fig. 1, the method includes steps 110, 120, 130 and 140. The method flow steps are only one possible implementation of the application.

Step 110, an electrochemical-thermal coupling model based on the prototype cell is constructed based on the material characteristic parameters, the electrode structure parameters, the cell design parameters and the cell thermal conduction parameters of the prototype cell.

Specifically, the electrode structure optimization method provided by the embodiment of the application is applied to a terminal, and the terminal can be various electronic devices with a display screen and supporting web browsing, including but not limited to a server, a smart phone, a tablet computer, a laptop portable computer, a desktop computer and the like,

The execution main body of the electrode structure optimization method provided by the embodiment of the application is an electrode structure optimization device, and the device can be independently arranged hardware equipment in a terminal or can be a software program running in the terminal. For example, when the terminal is a desktop computer, the electrode structure optimizing means may be embodied as an application program such as parameter optimizing software in the desktop computer.

The prototype cell is the initial cell to be electrode structure optimized. The electrodes of the prototype cell may comprise multiple layers of composite material.

The material characteristic parameters of the prototype battery can comprise particle size, a particle open-circuit voltage curve, an entropy coefficient, a solid-phase diffusion coefficient, exchange current density, reaction rate constant, maximum lithium ion density and reaction interval of the anode material and the cathode material of the prototype battery; at least one of the thickness, density, porosity, density of the electrolyte, liquid phase diffusion coefficient, and conductivity of the separator.

The electrode structural parameters of the prototype cell may include at least one of thickness of the positive and negative electrodes, active material volume ratio, porosity, conductivity, and tortuosity.

The cell design parameters of the prototype cell may include at least one of cell size, tab position and size, and cell specific surface area.

The cell heat transfer parameters of the prototype cell may include at least one of a cell thickness direction heat transfer coefficient and a cell plane direction heat transfer coefficient.

The electrochemical-thermal coupling model can be used to describe the electrochemical reaction process and the thermal change process of the prototype cell.

And 120, testing the prototype battery under different working conditions, and simulating the performance of the prototype battery under the same working condition based on the model.

Specifically, different working conditions are different testing conditions, such as different temperatures, different multiplying powers, and the like.

The electrochemical-thermal coupling model can be subjected to charge and discharge simulation tests under different working conditions, the use process of the prototype battery is simulated, and simulation test results output by the electrochemical-thermal coupling model under different working conditions are obtained. The simulation test results may include a charge voltage-capacity simulation curve, a discharge voltage-capacity simulation curve, a negative electrode potential-capacity simulation curve, and the like of the electrochemical-thermal coupling model.

Meanwhile, the prototype battery is subjected to charge and discharge tests under different working conditions, and actual test results of the prototype battery under different working conditions are obtained. The actual test results may include a charge voltage-capacity curve, a discharge voltage-capacity curve, a negative electrode potential-capacity curve, and the like of the prototype battery.

And 130, comparing the simulation test result with the actual test result, and correcting the model parameters of the electrochemical-thermal coupling model based on the comparison result.

Specifically, the simulation test result is compared with the actual test result.

If the simulation test result is consistent with the actual test result under the same working condition, the accuracy of the current electrochemical-thermal coupling model is higher, and the charge and discharge process of the prototype battery can be accurately simulated.

If the simulation test result is inconsistent with the actual test result under the same working condition, the current electrochemical-thermal coupling model cannot accurately simulate the charge-discharge process of the prototype battery, and model parameter correction is required to be carried out on the electrochemical-thermal coupling model until the corrected electrochemical-thermal coupling model can accurately simulate the charge-discharge process of the prototype battery.

And 140, optimizing the electrode structure parameters in the corrected model by taking the battery energy density, the battery cell thickness and the maximum lithium current as optimization targets to obtain the electrode structure optimization parameters of the prototype battery.

Specifically, the optimization target may be set according to the properties of the prototype battery or the actual application scenario. Optimization objectives may include battery energy density, cell thickness, and maximum no-lithium current, among others. For example, in U _neg >0V(U _neg Negative voltage), the energy density and the cell thickness meet the design requirements, which can be set according to actual conditions, as a final optimization target.

The corrected electrochemical-thermal coupling model takes an optimization target as a constraint condition, electrode structure parameters in the model are optimized, multiple groups of electrode structure design parameters can be obtained in the optimizing process, and the electrode structure optimization parameters of the prototype battery are selected from the multiple groups of electrode structure design parameters.

According to the electrode structure optimization method provided by the embodiment of the application, an electrochemical-thermal coupling model based on a prototype battery can be constructed through the material characteristic parameters, the electrode structure parameters, the battery design parameters and the battery thermal conduction parameters of the prototype battery; the electrode structure parameters in the corrected model are optimized by taking the battery energy density, the battery core thickness and the maximum non-lithium-precipitation current as optimization targets, the influence of the electrode structure parameters on the battery core thickness and the battery energy density is considered, the lithium precipitation safety of the negative electrode in the fast charging process of the high specific energy battery is considered, more accurate and high-feasibility electrode structure optimization parameters can be obtained, the electrode structure parameters are comprehensively optimized, and therefore the high specific energy, high power and high safety lithium ion battery is obtained, the comprehensive performance of the battery is improved, and the simulation result has more practical reference significance by effectively correlating the battery model parameters with the battery design parameters; based on an electrochemical-thermal coupling model, the electrode structure optimization method provided by the embodiment of the application can be more accurately applied to battery systems with different sizes, different models and different capacities.

It should be noted that each embodiment of the present application may be freely combined, exchanged in order, or separately executed, and does not need to rely on or rely on a fixed execution sequence.

In some embodiments, step 140 comprises:

taking one or more groups of electrode structure parameters as variables, performing DOE design on at least one electrode of the anode and the cathode, and obtaining a plurality of design schemes corresponding to the electrode structure parameters; electrode structural parameters include, but are not limited to, areal density, porosity, main material occupancy and tortuosity;

and comparing the calculation result with an optimization target, and optimizing each group of electrode structure parameters.

Specifically, when the electrode structural design parameters are determined by taking the optimization target as the constraint condition, the corrected electrochemical-thermal coupling model may obtain multiple groups of electrode structural design parameters meeting the constraint condition.

And each group of electrode structure design parameters corresponds to one electrode structure design scheme, and the DOE design is carried out on at least one electrode of the anode and the cathode by taking one or more groups of electrode structure parameters as variables to obtain a plurality of design schemes corresponding to the electrode structure parameters. And calculating the energy density, the cell thickness and the maximum lithium-ion-free current of the battery under each design scheme, comparing the calculated energy density, cell thickness and maximum lithium-ion-free current with the energy density, cell thickness and maximum lithium-ion-free current corresponding to the optimization target, and optimizing each group of electrode structure parameters according to the comparison result, thereby obtaining the electrode structure optimization parameters of the prototype battery.

The electrode structure parameters can include surface density, porosity, main material ratio, tortuosity and the like.

The method for calculating the battery energy density comprises the following steps:

integrating voltage, current and time during charging or discharging of battery to obtain battery energy W _Batt The method comprises the steps of carrying out a first treatment on the surface of the Summing the mass of each component in the battery to obtain the theoretical mass M of the battery _Batt Thereby obtaining the theoretical energy density E of the battery _Batt The method comprises the steps of carrying out a first treatment on the surface of the The obtained theoretical energy density and target energy density E of the battery _aim Alignment is carried out by E _Batt >E _aim Reference electrode structure for screening conditionOptimizing the number; voltage current is voltage multiplied by current.

The simulation result has a reference meaning by correlating the model simulation parameters with the actual design parameters of the battery through the following formula. The specific calculation formula is as follows:

M _Batt ＝m _pos +m _neg +m _sep +m _ele +m _Al +m _Cu

battery capacity Q _cell From the maximum lithium ion concentration cs_pos_max of the positive electrode material and the volume fraction epsilon of the positive electrode material _{s_pos} Thickness L of positive electrode _pos Total electrode area A _cell And (3) obtaining an SOC interval: q (Q) _cell ＝cs_pos_max*ε _{s_pos} *L _pos *F _const *(SOC _{max_pos} -SOC _{min_pos} )*A _cell

m _pos ＝Q _cell /Y/C _pos

m _neg ＝Q _cell /X/C _neg

m _Al ＝L _Al *ρ _Al *A _cell /2

m _cu ＝L _Cu *ρ _Cu *A _cell /2

Wherein ε _{l_pos} Is the volume fraction of pores in the positive electrode; f (F) _const Is Faraday constant; SOC (State of Charge) _{max_pos} The lithium is maximally intercalated into the anode; SOC (State of Charge) _{min_pos} The lithium is embedded into the positive electrode at minimum; y is the first efficiency of the battery; x is the proportion of the cathode capacity to the excess cathode capacity; x=q _neg /Q _pos ；Q _neg Is the capacity of the cathode material; q (Q) _pos Is the capacity of the positive electrode material; m is m _ele The electrolyte is of the mass; c (C) _pos The mass specific capacity of the positive electrode material; c (C) _neg The mass specific capacity of the cathode material; epsilon _{l_neg} A volume fraction of pores in the negative electrode; epsilon _{l_sep} Is the volume fraction of pores in the separator; l (L) _neg The thickness of the cathode electrode; l (L) _sep Is the thickness of the diaphragm; l (L) _Al The thickness of the positive electrode current collector is; l (L) _Cu Is the thickness of the negative current collector; ρ _ele Is the density of the electrolyte; ρ _Al Is the density of the positive current collector; ρ _Cu Is the density of the negative electrode current collector. Inter-letter is merely intended to separate letters and does not represent any meaning.

The method for calculating the thickness of the battery comprises the following steps:

N _pos ＝A _cell /A _pos /2

N _neg ＝N _pos +1

wherein A is _pos Design parameters for the area of the monolithic electrode; a is that _cell The total area of a single-sided electrode in the lithium ion battery simulated by the model; l (L) _aim The thickness of the battery cell is the target thickness; n (N) _pos For the number of positive electrode lamination layers, N _neg Is the number of the stacked layers of the negative electrode.

The method for obtaining the maximum lithium current without precipitation of the battery comprises the following steps:

the field probe is arranged at the negative electrode, and the battery is extracted at different multiplying powers I _rate Minimum voltage U of negative electrode in charging process _{neg_min} In U form _{neg_min} The maximum charging current at greater than 0V is the maximum no-lithium-evolution current.

According to the electrode structure optimization method provided by the embodiment of the application, the electrode structure parameters in the corrected model are optimized by taking the battery energy density, the battery core thickness and the maximum lithium current without analysis as optimization targets, so that the electrode structure parameters can be comprehensively optimized, a lithium ion battery with high specific energy, high power and high safety is obtained, and the comprehensive performance of the battery is improved.

In some embodiments, step 130 comprises:

the performance of the prototype cell under different conditions is tested and determined, including but not limited to one or more of the following conditions:

Testing the discharge voltage-capacity curve of the prototype battery under the same temperature and different multiplying power currents;

testing voltage-capacity curves of the prototype battery under the same temperature and different currents;

and determining a negative electrode potential-capacity curve of the prototype battery at different temperatures or different currents;

Specifically, prototype cells were tested under different conditions, such as:

testing charging voltage-capacity curves of the prototype battery under the same temperature and different multiplying power currents; testing discharge voltage-capacity curves of the prototype battery at the same current and different temperatures; testing the discharge voltage-capacity curve of the prototype battery under the same temperature and different multiplying power currents; testing voltage-capacity curves of the prototype battery under the same temperature and different currents; and determining negative electrode potential-capacity curves of the prototype battery at different temperatures or different currents, and taking the curves as actual test results of the prototype battery. And simulating the battery performance by adopting the same working condition as the prototype battery according to the electrochemical-thermal coupling model to obtain a simulation test result corresponding to the actual test result of the prototype battery.

And comparing the actual test result of the prototype battery with the simulation test result of the electrochemical-thermal coupling model, and determining whether the electrochemical-thermal coupling model needs correction or not.

According to the electrode structure optimization method provided by the embodiment of the application, through the charge voltage-capacity curve, the discharge voltage-capacity curve and the negative electrode potential-capacity curve, the comprehensive actual test result of the prototype battery and the simulation test result of the electrochemical-thermal coupling model can be obtained, and the accuracy of the electrochemical-thermal coupling model can be improved.

FIG. 2 is a schematic diagram of a two-dimensional structure of a prototype cell according to an embodiment of the present application; FIG. 3 is a schematic diagram showing a two-dimensional structure of a prototype cell according to an embodiment of the present application; FIG. 4 is a schematic diagram of a three-dimensional structure of a prototype cell according to an embodiment of the present application; FIG. 5 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application; FIG. 6 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application; FIG. 7 is a schematic diagram showing a two-dimensional structure of a prototype battery according to an embodiment of the present application; FIG. 8 is a schematic diagram of a two-dimensional structure of a prototype cell according to an embodiment of the present application; fig. 9 is a schematic three-dimensional structure of a prototype cell according to an embodiment of the present application; as shown in fig. 2 to 9, the prototype cell includes:

Negative electrode current collector 210, negative electrode 220, separator 230, positive electrode 240, and positive electrode current collector 250;

wherein the negative electrode 220 and/or the positive electrode 240 has one or more layers;

Q _cell ＝Q _pos1 +Q _pos2 +…+Q _posn

Q _posn ＝cs_posn_max*ε _{s_posn} *L _posn *F _const *(SOC _{max_pos} -SOC _{min_pos} )*A _cell

Electrolyte mass m in separator _{ele_sep} ：m _{ele_sep} ＝(ε _{l_sep} *L _sep )*ρ _ele *A _cell

L _pos ＝L _pos1 +L _pos2 +...+L _posn

L _neg ＝L _neg1 +L _neg2 +...+L _negn 。

Specifically, two-dimensional structural schematic diagrams of various prototype cells are illustrated in fig. 2 to 8. In order to facilitate distinguishing the components of the prototype battery, when the electrode is a multi-layer composite electrode, the electrodes of all layers in the composite electrode are separated by a broken line, the thickness in the model geometric figure is only schematic, the specific thickness is based on the actual calculated value, and when the electrode is a multi-layer electrode, at least two sub-layer parameters in all sub-layers are not completely the same.

As shown in fig. 2, the negative electrode in fig. 2 has a two-layer structure; the anode has a single-layer structure.

As shown in fig. 3, the negative electrode in fig. 3 has a three-layer structure; the anode has a single-layer structure.

As shown in fig. 4, the anode in fig. 4 has a two-layer structure, and the thickness of the electrode layer near one end of the anode current collector is thicker; the anode has a single-layer structure.

As shown in fig. 5, the negative electrode in fig. 5 has a two-layer structure, and the thickness of the electrode layer at one end far away from the negative electrode current collector is thicker; the anode has a single-layer structure.

As shown in fig. 6, the negative electrode in fig. 6 has a four-layer structure; the anode has a single-layer structure.

As shown in fig. 7, the negative electrode in fig. 7 has a two-layer structure, and the thickness of the electrode layer near one end of the negative electrode current collector is thicker; the anode has a two-layer structure.

As shown in fig. 8, the negative electrode in fig. 8 has a four-layer structure; the anode has a two-layer structure.

A three-dimensional schematic of the prototype cell is illustrated in fig. 9. As shown in fig. 9, the negative electrode in fig. 9 has a two-layer structure; the anode has a two-layer structure.

The layered structures of the positive electrode and the negative electrode according to the embodiment of the present application may be the same or different, and may be set according to actual conditions. The porosity and the porosity distribution of each layer structure of the positive electrode and the negative electrode are also set according to the actual situation.

The electrode in the electrochemical model of the embodiment of the application comprises or comprises one or more active material layers; when a plurality of active material layers are included in the electrode, wherein the structural parameters of the respective active material layers are different or the structural parameters of a part of the active material layers are different. The electrode structure in the electrochemical model, and the structural parameters of each active material layer are similar to those of the electrode structure and material layers of the prototype cell described above, and can be referred to correspondingly with each other.

As an alternative embodiment, step 140 further comprises:

inputting the structural parameters of each group of electrodes into a model, and simulating the performance of the battery to obtain E _batt 、L _batt And I _rate Comparing the obtained theoretical performance with the optimized target parameters, and screening the structural parameters of each group of electrodes by taking one or more conditions as limiting factors, wherein the method comprises the following steps:

E _batt >E _aim and L is _batt <L _aim And I _rate @25℃>2C；

Or E is _batt >E _aim And L is _batt <L _aim ；

Or L _batt <L _aim And I _rate @25℃>5C；

Or E is _batt >E _aim And I _rate @25℃>2C。

I _rate Multiplying power current I at 25 ℃ at 25 DEG C _rate The method comprises the steps of carrying out a first treatment on the surface of the 1C is the current used for 1 hour to discharge, i.e. 1 c=q _cell /3600 seconds.

In order to make the model simulation result more reliable than a real battery, parameters in the electrochemical model in the project couple the heat generating and heat transferring process of the battery, wherein the electrochemical-heat coupling model comprises a three-dimensional heat transferring model:

the battery heat conduction parameters in all directions in the three-dimensional heat transfer model are determined based on the normalized processing results of the component ratios of the prototype battery;

the heat exchange condition of the three-dimensional heat transfer is related to the actual working condition of the prototype battery.

Specifically, the three-dimensional heat transfer model is constructed according to the specification and the size of the prototype battery, and the thickness of the battery changes along with the design parameters of the electrode structure. The thermal conductivity coefficients of the battery in all directions in the three-dimensional heat transfer model can be obtained through normalization processing according to the component ratio of the negative electrode current collector, the negative electrode, the diaphragm, the positive electrode and the positive electrode current collector. The electrochemical heat generation is used as a heat source to conduct heat transfer and heat dissipation calculation in a three-dimensional model, and the average temperature is obtained, so that parameters related to the temperature in the electrochemical model can be obtained, and the parameters related to the temperature in the electrochemical reaction process are described by an Arrhenius equation.

According to the electrode structure optimization method provided by the embodiment of the application, the battery heat conduction parameters in all directions can be obtained through the three-dimensional heat transfer model, and the accuracy of the obtained electrode structure optimization parameters is improved.

The method for optimizing the electrode structure provided by the application will be further described below according to several specific comparison examples and simulation examples.

To produce a specific energy greater than 260Wh/kg, discharge P/u _batt The power @50% SOC is greater than 1200W/kg, the charging rate is greater than 2C, and the cell thickness is less than 12 um.

Comparison sample one

An electrochemical-thermal coupling model is established based on a prototype battery structure of the positive electrode/the diaphragm/the negative electrode, and the compaction density, the surface density and the like of the electrode are optimized by taking the maximization of energy density and the maximization of the product of energy density and power density as optimization targets; the battery is designed by using the obtained electrode structure optimization parameters, but the battery cannot be successfully prepared due to the fact that the thickness of the battery core is larger than 12um and is not matched with the production process in the actual battery preparation process.

Comparison sample II

An electrochemical-thermal coupling model is established based on a prototype battery structure of a positive electrode/a diaphragm/a negative electrode, and the thickness, the porosity, the compacted density, the area density and the like of the electrode are optimized by taking energy density larger than 260Wh/kg as an optimization target; and (3) designing the battery by using the obtained electrode structure optimization parameters, and finding that the prepared battery has a serious negative electrode lithium precipitation phenomenon in the 1C rate charging process.

Simulation example 1

An electrochemical-thermal coupling model is established based on a prototype battery structure of a Positive electrode/a diaphragm/a Negative electrode, energy density is maximized as an optimization target, and meanwhile, the surface density of an electrode, compaction, the capacity of the Negative electrode of the battery/the capacity (N/P) ratio of the Positive electrode of the battery and the like are optimized by taking the thickness of a battery core and the lithium-precipitation potential of the Negative electrode as screening conditions; and (3) designing a battery by using the obtained electrode structure optimization parameters, wherein the prepared battery has the energy density of 263Wh/kg, the thickness of an electric core of 11.8mm and no lithium precipitation phenomenon in the 2.2C rate charging process.

Simulation example two

An electrochemical-thermal coupling model is established based on a prototype battery structure of a positive electrode/diaphragm/negative electrode 1/negative electrode 2 shown in fig. 2 and composed of double-layer negative electrodes, energy density maximization is used as an optimization target, and meanwhile, the battery cell thickness and the negative electrode lithium precipitation potential are used as screening conditions, and the electrode surface density, compaction, N/P ratio and the like are optimized; the battery is designed by using the obtained electrode structure optimization parameters, and as the negative electrode in the model is composed of a plurality of simulation layers, the porosity of the electrode close to the current collector side is further optimized based on the model, and as a result, the reduction of the porosity of the current collector electrode can improve the overall specific energy of the battery with less influence on the rate performance (as shown in figure 10), the prepared battery has the energy density of 265Wh/kg, the thickness of the battery core of 11.5mm and no lithium precipitation phenomenon in the 2.2C rate charging process.

Simulation example III

An electrochemical-thermal coupling model is established based on a prototype battery structure of a positive electrode/diaphragm/negative electrode 1/negative electrode 2 shown in fig. 2 and composed of double-layer negative electrodes, energy density maximization is used as an optimization target, and meanwhile, the battery cell thickness and the negative electrode lithium precipitation potential are used as screening conditions, and the electrode surface density, compaction, N/P ratio and the like are optimized; the battery is designed according to the obtained electrode structure optimization parameters, because the negative electrode in the model is composed of multiple simulation layers, the influence of the change of the electrode porosity close to the separator side on the overall performance of the battery is researched based on the model, and the electrode structure is further optimized, so that the electrode porosity of the separator side is improved, and the specific energy of the battery is slightly reduced but the rate performance of the battery is remarkably improved. The prepared battery has the energy density of 261Wh/kg, the thickness of the battery core of 11.9mm and no lithium precipitation phenomenon in the 3C rate charging process (as shown in figure 11).

Simulation example four

And (3) establishing an electrochemical-thermal coupling model based on the prototype battery structure shown in fig. 3-6, further optimizing the pore distribution of the negative electrode, maximizing the energy density to be an optimization target, and simultaneously taking the thickness of the battery core and the lithium-precipitation potential of the negative electrode as screening conditions, and performing battery design according to the obtained electrode structure optimization parameters. FIG. 12 is a graph of a simulation test of simulation example III of the present application; as can be seen from fig. 12, having less porosity near the negative current collector can increase the energy density of the battery and has less impact on the battery power performance; the pores from the current collector side to the diaphragm side are distributed in steps, so that the battery has better comprehensive performance.

Simulation example five

Based on the multi-layer negative electrode battery structure shown in fig. 9, a three-dimensional porous electrode model is established, the pore structure and distribution of the negative electrode are optimized, the product of energy density and power density is maximized as an optimization target, meanwhile, the thickness of a battery core and the lithium-ion potential of the negative electrode are taken as screening conditions, the battery is designed according to the obtained electrode structure optimization parameters, and the battery has good comprehensive performance. Based on the electrode structure shown in fig. 9, the influence of pore distribution in the thickness direction in different electrode layers on polarization non-uniformity in the plane of the battery pole piece can be obtained, so that the electrode structure can be optimally designed.

Simulation example six

Based on the prototype battery structure shown in fig. 7 and 8, an electrochemical-thermal coupling model is established, and the pore gradient design can be further carried out on the positive electrode on the basis of the pore gradient design of the negative electrode, so that the battery has better comprehensive performance. And the energy density is maximized as an optimization target, and meanwhile, the battery cell thickness and the lithium-ion potential of the negative electrode are taken as screening conditions, so that the electrode structure parameters are optimized, and the battery has better comprehensive performance. The design of porosity distribution gradient is carried out on the positive electrode and the negative electrode, so that the separator side has higher porosity, the current collector side has lower porosity, and the battery has higher energy density and rate capability. The battery energy density of the prepared battery is 263Wh/kg, the thickness of the battery core is 11.7mm, and the phenomenon of lithium precipitation does not occur in the 3C rate charging process.

The electrode structure optimizing device provided by the embodiment of the application is described below, and the electrode structure optimizing device described below and the electrode structure optimizing method described above can be referred to correspondingly.

FIG. 13 is a schematic diagram of an electrode structure optimizing apparatus according to an embodiment of the present application, and as shown in FIG. 13, the apparatus includes a building block 1310, a testing block 1320, a correction block 1330, and a result block 1340.

A construction module 1310 for constructing an electrochemical-thermal coupling model of the prototype cell based on the material characteristic parameters, the electrode structure parameters, and the cell thermal conductivity parameters of the prototype cell;

a test module 1320 for performing simulation tests on the electrochemical-thermal coupling model at different temperatures and performing actual tests on the prototype cell at different temperatures;

the correction module 1330 is configured to compare the simulation test result with the actual test result, and correct the model parameter of the electrochemical-thermal coupling model based on the comparison result;

and a result module 1340, configured to optimize the electrode structure parameters in the corrected model with the battery energy density, the battery cell thickness and the maximum lithium current as optimization targets, to obtain the electrode structure optimization parameters of the prototype battery.

Specifically, according to an embodiment of the present application, any of the building module, the testing module, the correction module, and the result module may be combined in one module to be implemented, or any of the modules may be split into a plurality of modules.

Alternatively, at least some of the functionality of one or more of the modules may be combined with at least some of the functionality of other modules and implemented in one module.

At least one of the build module, test module, calibration module, and result module may be implemented, at least in part, as hardware circuitry, such as a Field Programmable Gate Array (FPGA), programmable Logic Array (PLA), system-on-chip, system-on-a-substrate, system-on-package, application Specific Integrated Circuit (ASIC), or by hardware or firmware, such as any other reasonable means of integrating or packaging the circuitry, or in any one of, or in any suitable combination of, software, hardware, and firmware.

Alternatively, at least one of the build module, the test module, the correction module, and the result module may be at least partially implemented as a computer program module which, when executed, performs the corresponding functions.

According to the electrode structure optimizing device provided by the embodiment of the application, an electrochemical-thermal coupling model based on a prototype battery can be constructed through the material characteristic parameters, the electrode structure parameters, the battery design parameters and the battery thermal conduction parameters of the prototype battery; the electrode structure parameters in the corrected model are optimized by taking the battery energy density, the battery core thickness and the maximum non-lithium-precipitation current as optimization targets, the influence of the electrode structure parameters on the battery core thickness and the battery energy density is considered, the lithium precipitation safety of the negative electrode in the fast charging process of the high specific energy battery is considered, and more accurate and high-feasibility electrode structure optimization parameters can be obtained, so that the electrode structure parameters are comprehensively optimized, the high specific energy, high power and high safety lithium ion battery is obtained, the comprehensive performance of the battery is improved, and the simulation result has more practical reference significance by effectively correlating the battery model parameters with the battery design parameters.

It should be noted that, the electrode structure optimizing device provided by the embodiment of the present application can implement all the method steps implemented by the embodiment of the electrode structure optimizing method, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the embodiment of the method in the embodiment are omitted.

Fig. 14 is a schematic structural diagram of an electronic device according to an embodiment of the present application, as shown in fig. 14, the electronic device may include: processor 1410, communication interface (Communications Interface) 1420, memory 1430 and communication bus (Communications Bus) 1440, wherein Processor 1410, communication interface 1420, memory 1430 communicate with each other via communication bus 1440. The processor 1410 may invoke logic commands in the memory 1430 to perform an electrode structure optimization method comprising:

constructing an electrochemical-thermal coupling model based on the prototype battery based on the material characteristic parameter, the electrode structure parameter, the battery design parameter and the battery heat conduction parameter of the prototype battery;

In addition, the logic commands in the memory described above may be implemented in the form of software functional modules and stored in a computer readable storage medium when sold or used as a stand alone product. Based on this understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in the form of a software product stored in a storage medium, comprising several commands for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The processor in the electronic device provided by the embodiment of the application can call the logic instruction in the memory to realize the method, and the specific implementation mode is consistent with the implementation mode of the method, and the same beneficial effects can be achieved, and the detailed description is omitted here.

Embodiments of the present application also provide a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform the methods provided by the above embodiments.

The specific embodiment is consistent with the foregoing method embodiment, and the same beneficial effects can be achieved, and will not be described herein.

The embodiments of the present application provide a computer program product comprising a computer program which, when executed by a processor, implements a method as described above.

The apparatus embodiments described above are merely illustrative, wherein the modules illustrated as separate components may or may not be physically separate, and the components shown as modules may or may not be physical, i.e., may be located in one place, or may be distributed over a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present application without undue burden.

Claims

1. An electrode structure optimization method, comprising:

2. The method for optimizing an electrode structure according to claim 1, wherein optimizing the electrode structure parameters in the corrected model with the battery energy density, the cell thickness and the maximum lithium-ion-free current as optimization targets to obtain the electrode structure optimization parameters of the prototype battery comprises:

3. The method of optimizing an electrode structure according to claim 1, wherein the method of calculating the battery energy density comprises:

integrating voltage, current and time during charging or discharging of battery to obtain battery energy W _Batt The method comprises the steps of carrying out a first treatment on the surface of the Summing the mass of each component in the battery to obtain the theoretical mass of the batteryM _Batt Thereby obtaining the theoretical energy density E of the battery _Batt The method comprises the steps of carrying out a first treatment on the surface of the The obtained theoretical energy density and target energy density E of the battery _aim Alignment is carried out by E _Batt ＞E _aim Optimizing electrode structure parameters for screening conditions;

the specific calculation formula is as follows:

M _Batt ＝m _pos +m _neg +m _sep +m _ele +m _Al +m _Cu

battery capacity Q _cell From the maximum lithium ion concentration cs_p os_max of the positive electrode material and the volume fraction epsilon of the positive electrode material _{s_pos} Thickness L of positive electrode _pos Total electrode area A _cell And (3) obtaining an SOC interval:

m _pos ＝Q _cell /Y/C _pos

m _neg ＝Q _cell /X/C _neg

m _Al ＝L _Al *ρ _Al *A _cell /2

m _Cu ＝L _cu *ρ _Cu *A _cell /2

4. The method for optimizing an electrode structure according to claim 3, wherein the method for calculating the thickness of the battery comprises:

N _pos ＝A _cell /A _pos /2

N _neg ＝N _pos +1

5. The method for optimizing electrode structure according to claim 3, wherein the method for obtaining maximum battery current without lithium analysis comprises setting a domain probe on the negative electrode, and extracting minimum voltage U of the negative electrode of the battery in the process of charging at different multiplying powers _{neg_min} In U form _{neg_min} The maximum charging current at greater than 0V is the maximum no-lithium-evolution current.

6. The method of claim 1, wherein said performing model parameter correction on said electrochemical-thermal coupling model comprises:

7. The electrode structure optimizing method according to claim 3, wherein the prototype cell comprises: the negative electrode current collector, the negative electrode, the diaphragm, the positive electrode and the positive electrode current collector;

Q _cell ＝Q _pos1 +Q _pos2 +…+Q _posn

electrolyte mass m _ele From mass m of electrolyte in the anode _{ele_neg} Electrolyte mass m in separator _{ele_sep} Mass m of electrolyte in positive electrode _{ele_pos} Is added up; the mass of electrolyte in each section is the mass of electrolyte in the pores of each section: m is m _ele ＝m _{ele_neg} +m _{ele_sep} +m _{ele_pos}

Electrolyte mass m in separator _{ele_sep} ：

L _pos ＝L _pos1 +L _pos2 +...+L _posn

L _neg ＝L _neg1 +L _neg2 +...+L _negn

8. The method for optimizing an electrode structure according to claim 4, wherein the method for optimizing the battery energy density, the cell thickness and the maximum lithium-ion-free current comprises:

E _Batt >E _aim and L is _batt <L _aim And I _rate @25℃>2C；

Or E is _Batt >E _aim And L is _batt <L _aim ；

Or L _batt <L _aim And I _rate @25℃>5C；

Or E is _Batt >E _aim And I _rate @25℃>2C；

9. The method for optimizing an electrode structure according to claim 1, wherein the material characteristic parameters mainly comprise particle size of positive and negative electrode materials, a particle open-circuit voltage curve, an entropy coefficient, a solid phase diffusion coefficient, an exchange current density, a reaction rate constant, a maximum lithium ion density and a reaction interval; at least one of thickness, density, porosity, density of electrolyte, liquid phase diffusion coefficient, and conductivity of the separator;

10. The method of claim 1, wherein the electrochemical-thermal coupling model comprises a three-dimensional heat transfer model: