Battery floating charge parameter acquisition method, battery charge control method, battery power management method and battery

Abstract

The invention provides a battery floating charge parameter acquisition method, a battery charge control method, a battery electric quantity management method and a battery, and the battery floating charge parameter acquisition method comprises the steps: acquiring a self-discharge rate K (T0, T0) of a preset battery at a set temperature T0 and a set capacity Q0; q0) and the change relation of dV / dQ along with the residual capacity of the battery in the discharging process of the preset battery at the set temperature T0; according to the change relation and the set capacity Q0 of the battery, the floating charge current of the preset battery at the set temperature T0 and the set capacity Q0 is obtained, I (T0, Q0) = K (T0, Q0) / (dV / dQ) (T0, Q0), and (dV / dQ) (T0, Q0) is the corresponding dV / dQ value of the set capacity Q0 in the change relation of dV / dQ along with the residual capacity of the battery in the discharging process at the set temperature T0. The floating charge current value obtained in the battery floating charge parameter obtaining method fully considers the preset battery self-discharge rate and the internal resistance condition of the battery, and the floating charge current can be effectively and dynamically adjusted to adapt to the dynamic characteristic change of the battery, so that the health state of the battery is effectively maintained, and the service life is prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery charge and discharge control, and specifically to a battery float charge parameter acquisition method, a battery charging control method, a battery power management method, and a battery. Background Art

[0002] Battery charge and discharge management technology is an important component of modern electronic devices. It involves issues such as battery charge and discharge characteristics, lifespan, and safety. During the battery charging process, ambient temperature is an important factor affecting the performance.

[0003] Existing technical solutions often only statically adjust the charging current without considering the dynamic characteristics of the battery, such as temperature and voltage changes. Furthermore, existing technical solutions also fail to consider the battery system and the impact of self-discharge. These issues can affect battery charging efficiency and safety. Summary of the Invention

[0004] In view of this, the embodiments of the present application are dedicated to providing a battery float charge parameter acquisition method, a battery charging control method, a battery power management method and a battery, so as to solve the problem in the prior art that the float charge current value affects the charging efficiency and safety of the battery.

[0005] On one hand, the present application provides a method for obtaining battery float charge parameters, comprising:

[0006] Obtain the self-discharge rate K(T0,Q0) of a preset battery at a set temperature T0 and a set capacity Q0;

[0007] Obtaining a relationship between dV / dQ and the remaining capacity of a preset battery during a discharge process at a set temperature T0;

[0008] Using the relationship between the dV / dQ of the preset battery during discharge at the set temperature T0 and the remaining capacity of the battery, and the set capacity Q0 of the battery, the float charge current of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula:

[0009] I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0);

[0010] Wherein, K(T0, Q0) is the self-discharge rate of the preset battery at the set temperature T0 and the set capacity Q0, and (dV / dQ)(T0, Q0) is the corresponding dV / dQ value of the set capacity Q0 in the relationship between dV / dQ during the discharge process at the set temperature T0 and the remaining capacity of the battery.

[0011] In one embodiment of the present application, the step of obtaining a preset self-discharge rate K of the battery at a set temperature T0 and a set capacity Q0 includes:

[0012] Discharging the preset battery to a set capacity Q0;

[0013] Obtaining an initial voltage OCV1 of the preset battery with a set capacity Q0 at a set temperature T0;

[0014] After placing the preset battery with the preset capacity Q0 at the set temperature T0 for a preset time period t, obtaining the terminal voltage OCV2 of the preset battery at the set temperature T0;

[0015] The self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula: K(T0, Q0)=(OCV1-OCV2) / t.

[0016] And / or, in the step of obtaining the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0, before discharging the preset battery to the set capacity Q0, the step further includes:

[0017] Discharging the preset battery at a 1C standard constant current until the discharge voltage of the preset battery reaches a preset discharge termination voltage;

[0018] The preset battery is charged at a constant current and then a constant voltage according to the 1C standard until the charging voltage reaches a preset charging limit voltage and the cut-off current reaches a preset cut-off current;

[0019] Discharging the preset battery at a 1C standard constant current to obtain the actual capacity C0 of the preset battery;

[0020] The preset battery is charged at a constant current according to the IC0 standard until the charging voltage reaches a preset charging limit voltage;

[0021] The step of discharging the preset battery to a set capacity Q0 includes:

[0022] The preset battery is discharged to the set capacity Q0 according to the 1C0 standard constant current.

[0023] In one embodiment of the present application, the step of obtaining the relationship between dV / dQ and the remaining capacity of a preset battery during discharge at a set temperature T0 includes:

[0024] The preset battery is charged first with constant current and then with constant voltage until the charging voltage reaches a preset charging limit voltage and the cut-off current reaches a preset cut-off current;

[0025] The preset battery is discharged at a constant current at a set temperature T0 until the discharge voltage of the preset battery reaches a preset discharge termination voltage, and the relationship between dV / dQ and the remaining capacity of the battery during the discharge process of the preset battery at the set temperature T0 is obtained.

[0026] In one embodiment of the present application, it further includes:

[0027] Obtain the float charge current I of a preset battery at multiple set temperatures and set capacities Q0;

[0028] Fitting the float charge current I of the preset battery at multiple set temperatures and set capacities Q0 to obtain a relationship between the float charge current I of the preset battery at the set capacity Q0 and temperature;

[0029] According to the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature, the floating charge current I of the preset battery at the set capacity Q0 and the selected temperature T is obtained. c Float charge current I c ;

[0030] The floating charge current I of the preset battery at the set capacity Q0 varies with temperature in the form of: I=a(TT m ) 2 +I m ;

[0031] Among them, a is the fitting coefficient, T m For any set temperature, I m The battery is set to the set temperature T m , set the float charge current under capacity Q0.

[0032] In one embodiment of the present application, it further includes:

[0033] The preset self-discharge rate K(T0, Q0) of the preset battery at the set temperature T0 and the set capacity Q0 is used to obtain the preset float charge time of the preset battery at the set temperature T0 and the set capacity Q0 based on the following formula:

[0034] t(T0,Q0)=K(T0,Q0)(T0-T max ) 2 ;

[0035] t(T0, Q0) is the preset floating charge time of the preset battery at the set temperature T0 and the set capacity Q0, T max The maximum operating temperature of the preset battery.

[0036] Another aspect of the present application provides a battery charging control method, comprising:

[0037] Charge the preset battery to the set capacity Q0;

[0038] A float charge is performed on a preset battery at a set temperature T0 and a set capacity Q0, wherein the float charge current during the float charge process is obtained according to the battery float charge parameter acquisition method.

[0039] In one embodiment of the present application, the step of performing float charging on a preset battery at a set temperature T0 and a set capacity Q0 includes:

[0040] The preset battery at the set temperature T0 and the set capacity Q0 is float charged for a preset float charge time, wherein the preset float charge time is obtained according to the battery float charge parameter acquisition method described in step 5.

[0041] Another aspect of the present application provides a battery power management method, comprising:

[0042] Get the current capacity Q of the battery m ;

[0043] The current capacity of the battery Q m When the capacity is greater than a first set capacity threshold, performing constant voltage float charging on the battery, wherein the float charging current used in the constant voltage float charging is configured to be acquired based on the battery float charging parameter acquisition method;

[0044] The current capacity of the battery Q m When the capacity of the battery is less than the second set capacity threshold, the battery is subjected to constant voltage discharge, and the cut-off current value of the constant voltage discharge is a float charge current value obtained based on the battery float charge parameter acquisition method;

[0045] Preferably, the first set capacity threshold is 15%-40%, and the second set capacity threshold is 60%-85%.

[0046] On the other hand, the present application provides a battery comprising a stacked positive electrode sheet, a separator and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode material, and the positive electrode material comprises LiMn2O4, Li4Ti5O 12 、Li3V2(PO4)3、LiFe 1-x W x PO4, LiW x Fe 1-x PO4、LiNi x Mn y Co 1-x-y O2 and LiNi x Co y Al 1-x-y At least one of O2, wherein 0≤x≤1, 0≤y≤1, x+y≤1, and W is selected from at least one of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, V, and Ti;

[0047] The negative electrode sheet includes a negative electrode material, and the negative electrode material includes at least one of graphite, mesophase carbon microspheres, silicon-carbon material, silicon-oxygen material, nano-silicon, and silicon alloy.

[0048] In one embodiment of the present application, the negative electrode material contains hard carbon, and the content of the hard carbon is 0-60%, preferably, the content of the hard carbon is 5-30%.

[0049] In the battery float charge parameter acquisition method of the present application, the float charge current value obtained by the above formula: I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0) fully takes into account the preset battery self-discharge rate and the internal resistance of the battery, and can effectively and dynamically adjust the float charge current to adapt to the dynamic characteristics of the battery, thereby effectively maintaining the health of the battery and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the steps of the battery float charge parameter acquisition method of the present application;

[0051] Figure 2 FIG2 is a schematic diagram showing another step of the method for obtaining battery float charge parameters of the present application;

[0052] Figure 3 Shown is a schematic diagram of some steps of the battery float charge parameter acquisition method of the present application;

[0053] Figure 4 Shown is a schematic diagram of some steps of the battery float charge parameter acquisition method of the present application;

[0054] Figure 5 Shown is a schematic diagram of some steps of the battery float charge parameter acquisition method of the present application;

[0055] Figure 6 Shown is a schematic diagram of the steps of the battery charging control method of the present application;

[0056] Figure 7 FIG2 is a schematic diagram showing another step of the battery charging control method of the present application;

[0057] Figure 8 Shown is a schematic diagram of the steps of the battery power management method of this application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] like Figures 1 to 5 As shown, the present application provides a method for obtaining battery float charge parameters, including:

[0060] Step S101: Obtain a preset self-discharge rate K(T0, Q0) of a battery at a set temperature T0 and a set capacity Q0.

[0061] It can be understood that the self-discharge rate K(T0, Q0) of a preset battery at a set temperature T0 and a set capacity Q0 is the rate at which the preset battery loses capacity due to internal chemical reactions in an open circuit state at the set temperature T0 and the set capacity Q0. The main purpose of floating charge of a preset battery is to compensate for the self-discharge loss of the preset battery, ensuring that the battery can maintain the set capacity Q0 state to offset the capacity loss caused by self-discharge. Therefore, there is a direct relationship between the self-discharge rate and the float charge current value.

[0062] Specifically, in one embodiment of the present application, the self-discharge rate K(T0, Q0) of a preset battery at a set temperature T0 and a set capacity Q0 can be obtained in a variety of ways, which are not limited here.

[0063] Step S102: Obtaining a relationship between dV / dQ and the remaining capacity of a preset battery during discharge at a set temperature T0.

[0064] The relationship between the dV / dQ and the remaining capacity of a preset battery during discharge at a preset temperature T0 reflects how quickly the discharge voltage changes with the capacity during discharge. Specifically, during discharge, the rate of voltage drop depends primarily on the battery's internal resistance. The greater the internal resistance, the faster the voltage drop.

[0065] It is understandable that step S101 and step S102 may be performed in any order or simultaneously, and are not limited here.

[0066] Step S103: Using the relationship between the dV / dQ value and the remaining capacity of the battery during the discharge process at the set temperature T0 and the set capacity Q0 of the battery, the float charge current of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula: I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0);

[0067] Wherein, K(T0,Q0) is the self-discharge rate of the preset battery at the set temperature T0 and the set capacity Q0, and (dV / dQ)(T0,Q0) is the corresponding dV / dQ value of the set capacity Q0 in the relationship between dV / dQ and the remaining capacity of the battery during the discharge process at the set temperature T0.

[0068] As mentioned above, the relationship between the dV / dQ ratio and the remaining capacity of a preset battery during discharge at a set temperature T0 can reflect the internal resistance of the preset battery. For batteries in good health, the internal resistance is small and its chemical reaction is relatively stable. In this case, the float charge current is mainly used to compensate for the battery's self-discharge. Due to the low internal resistance, the battery can more effectively accept the float charge current and maintain its voltage and charge. However, for batteries with a higher degree of aging, due to factors such as internal electrolyte decomposition and electrode material aging, the internal resistance is generally large, and the battery's ability to accept the float charge current will decrease. When the float charge current is too large, it may even lead to increased polarization within the battery, further accelerating battery aging.

[0069] Therefore, in the battery float charge parameter acquisition method of the present application, the float charge current value obtained by the above formula: I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0) fully takes into account the preset battery self-discharge rate and the internal resistance of the battery, and can effectively and dynamically adjust the float charge current to adapt to the dynamic characteristics of the battery, thereby effectively maintaining the health of the battery and extending the battery life.

[0070] It is understandable that the step S101 of obtaining the self-discharge rate K(T0, Q0) of the preset battery at the set temperature T0 and the set capacity Q0 can be selected as needed.

[0071] Specifically, such as Figure 2 As shown, in one embodiment of the present application, the step of obtaining the self-discharge rate K of a preset battery at a set temperature T0 and a set capacity Q0 includes:

[0072] Step S1015: Discharge the preset battery to a set capacity Q0;

[0073] Step S1016: Obtaining the initial voltage OCV1 of a preset battery with a set capacity Q0 at a set temperature T0;

[0074] Step S1017: After placing a preset battery with a preset capacity Q0 at a preset temperature T0 for a preset time period t, obtain the terminal voltage OCV2 of the preset battery at the set temperature T0;

[0075] Step S1018: Obtain the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0 based on the following formula: K(T0, Q0)=(OCV1-OCV2) / t.

[0076] Using the above method, the self-discharge rate K(T0, Q0) of the preset battery at the set temperature T0 and the set capacity Q0 can be accurately obtained, thereby ensuring the accuracy of the self-discharge rate K data of the preset battery at the set temperature T0 and the set capacity Q0, and further ensuring the accuracy of the float charge current of the obtained preset battery at the set temperature T0 and the set capacity Q0.

[0077] Further, such as Figure 3 As shown, in one embodiment of the present application, in the step of obtaining the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0, before discharging the preset battery to the set capacity Q0, the step further includes:

[0078] Step S1011: Discharge the preset battery at a 1C standard constant current until the discharge voltage of the preset battery reaches a preset discharge termination voltage.

[0079] It is understood that discharging the preset battery according to the 1C standard constant current means discharging the preset battery according to the current value corresponding to the nominal capacity of the preset battery. For example, if the capacity of the preset battery is 10000mAh, discharging the preset battery according to the 1C standard constant current means discharging the preset battery at a constant current of 10000mAh.

[0080] Since constant current discharge of the preset battery is stopped when the discharge voltage of the preset battery reaches the preset discharge termination voltage, the time required for 1C standard constant current discharge of the preset battery varies depending on the preset discharge termination voltage.

[0081] Step S1012: charging the preset battery with a constant current and then a constant voltage according to the 1C standard until the charging voltage reaches a preset charging limit voltage and the cut-off current reaches a preset cut-off current.

[0082] It can be understood that the preset battery is first charged with constant current and then with constant voltage according to the 1C standard until the charging voltage is the preset charging limit voltage and the cut-off current is the preset cut-off current. It means that constant current charging is first performed according to the current value corresponding to the nominal capacity of the preset battery. During this constant current charging process, the charging voltage continues to rise. After the charging voltage reaches the preset charging limit voltage, the preset battery is maintained at the preset charging limit voltage for constant voltage charging. During this constant voltage charging process, the charging current will continue to decrease. After the charging current drops to the preset cut-off current, charging is stopped.

[0083] Step S1013: Discharge the preset battery at a 1C standard constant current to obtain the actual capacity C0 of the preset battery.

[0084] It is understood that when a preset battery is discharged at a 1C standard constant current, the discharge current value is the current value corresponding to the nominal capacity of the preset battery; the product of the constant current discharge time of the preset battery at the current value corresponding to the nominal capacity of the preset battery and the current value corresponding to the nominal capacity is the actual capacity C0 of the preset battery. Because the capacity of the battery will be lost after long-term use, the actual capacity C0 of the preset battery is usually less than its nominal capacity; however, it is not ruled out that for batteries in good health, the actual capacity C0 is equal to or even greater than its nominal capacity.

[0085] Step S1014: Constant current charging is performed on the preset battery using the IC0 standard until the charging voltage reaches a preset charging limit voltage.

[0086] Charging the preset battery according to the 1C0 standard constant current means charging the preset battery according to the actual capacity C0 corresponding to the current value.

[0087] Step S1015: Discharging the preset battery to a set capacity Q0 includes:

[0088] Step S10151: Discharge the preset battery to a set capacity Q0 according to the 1C0 standard constant current.

[0089] That is, in the battery float charge parameter acquisition method of the present application, when obtaining the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0, the actual capacity of the preset battery is first obtained, and then the preset battery is charged with a constant current according to the 1C0 standard, and then discharged to the set capacity Q0. This can effectively eliminate the influence of the battery degree on the subsequently obtained float charge current value, and ensure that the preset battery can be discharged to the set capacity Q0.

[0090] Specifically, for a preset battery, the specific steps of obtaining the self-discharge rate K of the preset battery at a set temperature T0 and a set capacity Q0 may include:

[0091] Discharge the preset battery with a constant current of 1C standard to a discharge termination voltage of 2.2V, and let it sit for 30 minutes; then charge with a constant current and constant voltage of 1C standard to a charge limit voltage of 3.65V, with a cut-off current of 0.05C, and let it sit for 30 minutes; discharge the preset battery with a constant current of 1C standard to a discharge termination voltage of 2.2V, obtain the actual capacity C0 of the preset battery, and let it sit for 30 minutes; charge the preset battery with a constant current of 1C0 standard to a charge limit voltage of 3.65V, and then discharge it with 1C0 to the set capacity Q0, and let it sit for 30 minutes;

[0092] Obtain an initial voltage OCV1 of a preset battery with a set capacity Q0 at a set temperature T0; after the preset battery with the set capacity Q0 is placed at the set temperature T0 for 4 hours or other duration in a dormant state, obtain a terminal voltage OCV2 of the preset battery at the set temperature T0; obtain a self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0 based on the following formula: K(T0, Q0) = (OCV1-OCV2) / 30D, in units of mV / D.

[0093] That is, the preset discharge end voltage can be 2.2V, the preset charge limit voltage can be 3.65V, and the preset cutoff current can be 0.05C. Before and after charging and discharging, the preset battery is left for a certain period of time to effectively dissipate the heat generated by the battery during the charging and discharging process, so that the battery state tends to be stable.

[0094] It is understandable that the specific steps of step S102: obtaining the relationship between dV / dQ and the remaining capacity of the battery during the discharge process of the preset battery at the set temperature T0 can also be selected according to needs.

[0095] like Figure 4 As shown, in one embodiment of the present application, step S102: obtaining the relationship between dV / dQ and the remaining capacity of a preset battery during discharge at a set temperature T0 includes:

[0096] Step S1021: charging the preset battery with constant current and then constant voltage until the charging voltage reaches a preset charging limit voltage and the cutoff current reaches a preset cutoff current;

[0097] As mentioned above, the preset battery is first charged with constant current and then with constant voltage until the charging voltage reaches the preset charging limit voltage and the cut-off current is the preset cut-off current. This means that the preset battery is first charged with constant current. During the constant current charging process, the charging voltage continues to rise. After the charging voltage reaches the preset charging limit voltage, the preset battery is kept at the preset charging limit voltage for constant voltage charging. During the constant voltage charging process, the charging current will continue to decrease. After the charging current drops to the preset cut-off current, charging is stopped.

[0098] Step S1022: Discharge the preset battery at a constant current at a set temperature T0 until the discharge voltage of the preset battery reaches a preset discharge termination voltage, and obtain the relationship between dV / dQ and the remaining capacity of the battery during the discharge process of the preset battery at the set temperature T0.

[0099] It can be understood that when the preset battery is discharged at a constant current at a set temperature T0, multiple sets of real-time discharge voltage values ​​and corresponding remaining capacity values ​​can be obtained in real time to obtain the relationship between dV / dQ and the remaining capacity of the battery during the discharge process of the preset battery at the set temperature T0.

[0100] Specifically, during the data processing process, relevant data processing tools can be used to simplify the relationship between the discharge voltage of the preset battery during the discharge process at the set temperature T0 and the remaining capacity of the battery to simplify the numerical value. Then, the relationship between the discharge voltage of the preset battery during the discharge process at the set temperature T0 and the remaining capacity of the battery is differentiated once to obtain the relationship between dV / dQ of the preset battery during the discharge process at the set temperature T0 and the remaining capacity of the battery, in units of mV / Ah.

[0101] Furthermore, in the battery float charge parameter acquisition method of the present application, after obtaining the float charge current of the preset battery at the set temperature T0 and the set capacity Q0, in order to expand the scope of application of the battery float charge parameter acquisition method of the present application;

[0102] like Figure 5 As shown, in one embodiment of the present application, the battery float charge parameter acquisition method of the present application further includes:

[0103] Step S201: Obtain the float charge current I of a preset battery at multiple set temperatures and set capacities Q0.

[0104] The floating charge current I of the preset battery at multiple set temperatures and set capacities Q0 refers to the above steps and will not be repeated here.

[0105] Step S202: fitting the float charge current I of the preset battery at multiple set temperatures and set capacities Q0 to obtain a relationship between the float charge current I of the preset battery at the set capacity Q0 and temperature;

[0106] Specifically, relevant data processing tools may be used to fit the float charge current I of a preset battery at multiple set temperatures and set capacities Q0 to obtain a relationship between the float charge current I of the preset battery at the set capacity Q0 and temperature.

[0107] Step S203: According to the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature, obtain the current I of the preset battery at the set capacity Q0 and the selected temperature T c Float charge current I c .

[0108] According to the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature, the floating charge current I of the preset battery at the set capacity Q0 and any selected temperature T can be obtained. c Float charge current I c , so that the preset battery is at any selected temperature T c Under these conditions, the corresponding float charge current I can be obtained by using the battery float charge parameter acquisition method of the present application. c value for float charge.

[0109] It is understandable that there may be various forms of the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature.

[0110] In one embodiment of the present application, the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature is as follows: I=a(TT m ) 2 +I m ; where a is the fitting coefficient, T m For any set temperature, I m The battery is set to the set temperature T m , set the float charge current under capacity Q0.

[0111] That is, the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature is in the form of a quadratic curve. After verification, the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature is in the form of a quadratic curve, which is more in line with the actual situation of the floating charge current I at the set capacity Q0 changing with the temperature.

[0112] According to analysis, the floating charge current is often affected by the superposition of physical self-discharge and chemical self-discharge.

[0113] Among them, chemical self-discharge increases with increasing temperature, and the change of chemical self-discharge with temperature is approximately quadratic, while physical self-discharge is basically unaffected by temperature; therefore, the relationship between the change of float charge current I of the preset battery at the set capacity Q0 and temperature is basically in the form of a quadratic curve.

[0114] In a specific embodiment of the present application, a preset battery is at a set capacity Q0 and a set temperature T m The corresponding float charge current value at -25℃ is 4.28mA, and the set temperature T m The corresponding float charge current value at 25℃ is 5.89mA, and the set temperature T m The corresponding float charge current value at 45°C is 7.88mA, and the set temperature T m The corresponding float charge current value at 60°C is 10.24mA. Therefore, the relationship between the float charge current I of the preset battery at the set capacity Q0 and the temperature is I=0.0011T 2 +0.0308T+4.3659, the R of this curve 2 =0.9991, it can be seen that the fitting degree of the curve is extremely high, which is quite consistent with the actual situation of the floating charge current I changing with temperature under the set capacity Q0.

[0115] It is understandable that in order to use float charge to slowly increase the battery's depth of charge, it is not necessary to maintain float charge for a long time, but only to float charge for a period of time. In addition, the float charge time is related to the temperature. At low temperatures, due to the rapid increase in battery polarization, it usually takes a longer time to effectively increase the battery's depth of charge; at high temperatures, a shorter float charge time is usually enough to effectively achieve the purpose of increasing the battery's depth of charge.

[0116] Therefore, if Figure 1 As shown, in one embodiment of the present application, the battery float charge parameter acquisition method of the present application further includes:

[0117] Step S104: Using the self-discharge rate K(T0, Q0) of the preset battery at the set temperature T0 and the set capacity Q0, the preset float charge time of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula: t(T0, Q0) = K(T0, Q0)(T0-T max ) 2 ;

[0118] t(T0,Q0) is the preset float charge time of the preset battery at the set temperature T0 and the set capacity Q0, T max The maximum operating temperature of the preset battery.

[0119] After verification, the preset float charge time of the preset battery obtained above at the set temperature T0 and the set capacity Q0 takes into account the self-discharge rate of the preset battery at the set temperature T0 and the set capacity Q0, and also takes into account that the set temperature T0 is more consistent with the actual situation that the preset float charge time I of the preset battery at the set temperature T0 and the set capacity Q0 changes with the set temperature T0.

[0120] In a specific embodiment of the present application, a preset battery is at a set capacity Q0 and a set temperature T m The corresponding float charge time at -25℃ is 180h, and the set temperature T m The corresponding float charge time at 25℃ is 50h, and the set temperature T m The corresponding float charge time at 45°C is 20h, and the set temperature T m The corresponding float charge time at 60℃ is 4h, and the set temperature T m The corresponding float charge time at 80°C is 0.5h. Therefore, the preset float charge time curve of the preset battery at the set temperature T0 and the set capacity Q0 is t=0.0164T0 2 -2.6227T0+104.41, the R of this curve 2=0.9991, it can be seen that the fitting degree of the curve is extremely high, which is quite consistent with the actual situation that the preset float charge time I of the preset battery at the set temperature T0 and the set capacity Q0 changes with the set temperature T0.

[0121] like Figure 6 As shown, the present application also provides a battery charging control method, comprising:

[0122] Step S301: charging the preset battery to a set capacity Q0;

[0123] Step S302: Float charge the preset battery at the set temperature T0 and the set capacity Q0.

[0124] It can be understood that the float charge current during the float charge process is obtained according to the above-mentioned battery float charge parameter acquisition method.

[0125] Since the float charge current value obtained by the above formula: I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0) in the battery float charge parameter acquisition method of the present application fully takes into account the preset battery self-discharge rate and the internal resistance of the battery, therefore, when the battery charging control method of the present application uses the float charge current obtained by the above battery float charge parameter acquisition method for float charging, it can effectively adapt to the dynamic characteristics changes of the battery, effectively compensate for the self-discharge loss, maintain the battery voltage stability, effectively increase the battery charging depth, and effectively maintain the health of the battery and extend the battery life.

[0126] It is understandable that when floating charge is performed on a battery, the floating charge voltage setting used needs to be adjusted according to the battery type, actual capacity and actual usage environment to ensure the safety and service life of the battery.

[0127] Further, such as Figure 7 As shown, in one embodiment of the present application, step S302: the step of floating charging a preset battery at a set temperature T0 and a set capacity Q0 includes:

[0128] Step S3021: performing float charging for a preset float charging time on a preset battery at a set temperature T0 and a set capacity Q0.

[0129] The preset float charge time is obtained according to the above-mentioned battery float charge parameter acquisition method.

[0130] It is understandable that in order to use float charge to slowly increase the battery's depth of charge, it is not necessary to maintain float charge for a long time, but only to float charge for a period of time. In addition, the float charge time is related to the temperature. At low temperatures, due to the rapid increase in battery polarization, it usually takes a longer time to effectively increase the battery's depth of charge; at high temperatures, a shorter float charge time is usually enough to effectively achieve the purpose of increasing the battery's depth of charge.

[0131] The preset float charge time of the preset battery at the set temperature T0 and the set capacity Q0 obtained by the battery float charge parameter acquisition method of the present application takes into account the self-discharge rate of the preset battery at the set temperature T0 and the set capacity Q0, and also takes into account that the set temperature T0 is more consistent with the actual situation that the preset float charge time I of the preset battery at the set temperature T0 and the set capacity Q0 changes with the set temperature T0, which is beneficial to maintaining the health of the battery and extending the service life of the battery.

[0132] It is understandable that for lithium-ion batteries, the charging and discharging process is achieved through the insertion and extraction of lithium ions in the crystals of layered materials, resulting in energy changes. Under normal charging and discharging conditions, the insertion and extraction of lithium ions generally only cause changes in the interlayer spacing, and do not cause damage to the crystal structure. Over-discharging will cause the negative electrode carbon to release excessive lithium ions, causing its layer structure to collapse, affecting the charging and discharging efficiency of the lithium-ion battery; overcharging can easily force too many lithium ions into the negative electrode carbon structure, making it difficult for some lithium ions to be released. In addition, the lithium ions deposited on the surface of the negative electrode carbon have a serious impact on safety. For other types of batteries, overcharging and over-discharging are also harmful, which will not be discussed here.

[0133] Therefore, if Figure 8 As shown, the present application also provides a battery power management method, including:

[0134] Step S401: Obtain the current capacity Q of the battery m ;

[0135] Step S402: At the current capacity Q of the battery m When the capacity is greater than the first set capacity threshold, the battery is subjected to constant voltage float charging, and the float charging current used by the constant voltage float charging is configured to be obtained based on the above-mentioned battery float charging parameter acquisition method; when the current capacity Q of the battery is m When the capacity is less than the second set capacity threshold, the battery is discharged at a constant voltage, and the cut-off current value of the constant voltage discharge is the float charge current value obtained based on the above-mentioned battery float charge parameter acquisition method.

[0136] That is, the current capacity of the battery Q mWhen the capacity is greater than the first set capacity threshold, the battery is subjected to constant voltage float charging, and the float charging current used for the constant voltage float charging is configured to be obtained based on the above-mentioned battery float charging parameter acquisition method to avoid overcharging the battery and effectively maintain the health of the battery and its capacity.

[0137] That is, the current capacity of the battery Q m When the capacity is less than the second set capacity threshold, the battery is discharged at a constant voltage, and the cutoff current value of the constant voltage discharge is the float charge current value obtained based on the above-mentioned battery float charge parameter acquisition method, so as to avoid excessive discharge of the battery and effectively maintain the health of the battery and its capacity.

[0138] It is understandable that for the current capacity Q of the battery m When the capacity is greater than the first set capacity threshold and less than the second set capacity threshold, the battery can be subjected to either constant voltage float charge or constant voltage discharge, which is not limited here.

[0139] Specifically, in one embodiment of the present application, the first set capacity threshold is 15%-40%, and the second set capacity threshold is 60%-85%. m When the battery capacity is greater than the first set value between 15% and 40%, the battery is subjected to constant voltage float charging. The float charging current used by the constant voltage float charging is configured to be obtained based on the above-mentioned battery float charging parameter acquisition method to avoid overcharging the battery and effectively maintain the health of the battery and its capacity. m When the current is less than the second set value between 60% and 85%, the battery is discharged at a constant voltage. The cut-off current value of the constant voltage discharge is the float charge current value obtained based on the above-mentioned battery float charge parameter acquisition method, so as to avoid excessive discharge of the battery and effectively maintain the health of the battery and its capacity. m When the voltage is greater than a first set value between 15% and 40% and less than a second set value between 60% and 85%, the battery can be subjected to either constant voltage float charge or constant voltage discharge, which is not limited here.

[0140] After experiments, it was found that in the battery power management method of the present application, when the first set capacity threshold is 15%-40% and the second set capacity threshold is 60%-85%, the health of the battery can be effectively guaranteed and the service life of the battery can be extended.

[0141] The present application also provides a battery comprising a stacked positive electrode sheet, a separator and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode material, and the positive electrode material comprises LiMn2O4, Li4Ti5O 12 、Li3V2(PO4)3、LiFe 1-x W x PO4, LiW x Fe1-x PO4、LiNi x Mn y Co 1-x-y O2 and LiNi x Co y Al 1-x-y At least one of O2, wherein 0≤x≤1, 0≤y≤1, x+y≤1, and W is selected from at least one of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, V and Ti; the negative electrode sheet includes a negative electrode material, and the negative electrode material includes at least one of graphite, mesophase carbon microbeads, silicon-carbon material, silicon-oxygen material, nano-silicon, and silicon alloy.

[0142] After experiments, it was found that the battery float charge parameter acquisition method, battery charging control method, and battery power management method in the present application can be effectively applied to the above-mentioned battery, can effectively improve the health status of the above-mentioned battery, and extend the service life of the battery.

[0143] In one embodiment of the present application, the negative electrode material of the battery described above contains hard carbon, with the hard carbon content ranging from 0% to 60%. Compared with common negative electrode materials such as graphite, hard carbon has a larger interlayer spacing, more defects, and a higher specific surface area, which can effectively improve the battery's cold-crank performance. However, excessive hard carbon content can increase battery self-discharge, affect the battery's high-temperature storage capacity, and thus shorten its lifespan.

[0144] Therefore, referring to Table 1 below, in the battery of the present application, since the negative electrode material of the battery contains hard carbon, and the content of hard carbon is 0-60%, it can effectively improve the cold start performance of the battery without excessively increasing the self-discharge of the battery, resulting in a decrease in the storage capacity retention rate of the battery.

[0145] Hard carbon content Cold start voltage (V) Storage capacity retention rate Self-discharge rate (mV / h) 14.25wt% 1.91 95.4％ 0.0146 28.5wt% 2.04 94.1％ 0.0217 0wt% 1.82 96.8％ 0.0091 76wt% 2.08 88.2％ 0.0569

[0146] Table 1

[0147] Furthermore, in one embodiment of the present application, the content of hard carbon is 5-30%. When the content of hard carbon is 5-30%, the cold start performance, self-discharge and storage capacity retention of the battery can be effectively balanced to improve the overall performance of the battery.

[0148] It is understood that the battery can be a battery of various systems. For example, in one embodiment of the present application, the positive electrode material of the battery includes LiMn2O4, Li4Ti5O 12 、Li3V2(PO4)3、LiFe 1-x W x PO4, LiW x Fe 1-x PO4、LiNi x Mn yCo 1-x-y O2 and LiNi x Co y Al 1-x-y At least one of O2, wherein 0≤x≤1, 0≤y≤1, x+y≤1, and W is selected from at least one of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, V and Ti; the negative electrode material of the battery also includes at least one of graphite, mesophase carbon microbeads, silicon-carbon materials, silicon-oxygen materials, nano-silicon, and silicon alloys.

[0149] Specifically, in the above test steps, the cold start test method of the battery is: in an environment of (25±2)℃, the battery is discharged to 2.2V according to the 1C standard constant current and constant voltage, and left for 30 minutes; the battery is then charged to 3.65V according to the 1C standard constant current and constant voltage, with a cut-off current of 0.05C, and left for 30 minutes; the battery is discharged to 2.2V according to the 1C standard constant current and constant voltage, and the actual capacity C0 is obtained; left for 30 minutes; the battery is charged to 3.65V according to the 1C0 standard constant current and constant voltage, with a cut-off current of 0.05C, and the battery is discharged according to the 1C0 standard for 30 minutes, that is, the actual capacity of the battery is 50% SOC; in an environment of (25±2)℃, let it stand for 2 hours; the battery is placed in a -30℃ constant temperature box and maintained at a constant temperature for 4 hours; the terminal voltage value of the battery under the 18C standard constant current discharge for 0.2s is the cold start voltage, in V.

[0150] The test method for the storage capacity retention rate of the battery is as follows: at (25±2)℃, discharge the battery at 1C standard constant current to a discharge termination voltage of 2.2V, and leave it for 30min; then charge the battery at 1C standard constant current and constant voltage to a charge limit voltage of 3.65V, with a cut-off current of 0.05C, and leave it for 30min; discharge the battery at 1C standard constant current to a discharge termination voltage of 2.2V to obtain the initial capacity C0, and leave it for 30min; then charge the battery at 1C standard constant current and constant voltage to a charge limit voltage of 3.65V, with a cut-off current of 0.05C, and leave it for 30min. .65V, cut-off current 0.05C, then open circuit the battery at 45℃ for 30 days; leave the battery at (25±2)℃ for 1h, discharge the battery at 1C standard constant current to the discharge termination voltage of 2.2V, then charge the battery at 1C standard constant current and constant voltage to the charge limit voltage of 3.65V, cut-off current 0.05C, then discharge at 1C standard constant current to the discharge termination voltage of 2.2V, and obtain the recovery capacity C1; wherein the recovery capacity retention rate of the battery cell is C1 / C0*100%.

[0151] The self-discharge rate test method for this battery is as follows: At (25±2)°C, discharge the battery at a standard 1C constant current to a discharge cutoff voltage of 2.2V and allow it to rest for 30 minutes. Then, charge the battery at a standard 1C constant current and constant voltage to a charge limit voltage of 3.65V, with a cutoff current of 0.05C, and allow it to rest for 30 minutes. Discharge the battery at a standard 1C constant current to a discharge cutoff voltage of 2.2V, record the actual cell capacity (C0), and allow it to rest for 30 minutes. Charge the battery at a standard 1C0 constant current to 36% SOC, then discharge it at a standard 1C0 to 3% SOC, at which point the battery capacity is 33% SOC, and allow it to rest for 30 minutes. Record the initial voltage (OCV1). After storing at room temperature for 15 days, record the terminal voltage (OCV2). The self-discharge rate of the battery cell = (OCV1-OCV2) / storage time, expressed in mV / h.

[0152] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for obtaining battery float charge parameters, characterized in that: include: Obtain the self-discharge rate K(T0,Q0) of a preset battery at a set temperature T0 and a set capacity Q0; Obtaining a relationship between dV / dQ and the remaining capacity of a preset battery during a discharge process at a set temperature T0; Using the relationship between the dV / dQ of the preset battery during discharge at the set temperature T0 and the remaining capacity of the battery, and the set capacity Q0 of the battery, the float charge current of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula: I(T0,Q0)=K(T0,Q0) / (dV / dQ)(T0,Q0); Wherein, K(T0, Q0) is the self-discharge rate of the preset battery at the set temperature T0 and the set capacity Q0, and (dV / dQ)(T0, Q0) is the corresponding dV / dQ value of the set capacity Q0 in the relationship between dV / dQ during the discharge process at the set temperature T0 and the remaining capacity of the battery.

2. The battery float charge parameter acquisition method according to claim 1, characterized in that: The step of obtaining the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0 includes: Discharging the preset battery to a set capacity Q0; Obtaining an initial voltage OCV1 of the preset battery with a set capacity Q0 at a set temperature T0; After placing the preset battery with the preset capacity Q0 at the set temperature T0 for a preset time period t, obtaining the terminal voltage OCV2 of the preset battery at the set temperature T0; The self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0 is obtained based on the following formula: K(T0,Q0)=(OCV1-OCV2) / t; And / or, in the step of obtaining the self-discharge rate K of the preset battery at the set temperature T0 and the set capacity Q0, before discharging the preset battery to the set capacity Q0, the step further includes: Discharging the preset battery at a 1C standard constant current until the discharge voltage of the preset battery reaches a preset discharge termination voltage; The preset battery is charged at a constant current and then a constant voltage according to the 1C standard until the charging voltage reaches a preset charging limit voltage and the cut-off current reaches a preset cut-off current; Discharging the preset battery at a 1C standard constant current to obtain the actual capacity C0 of the preset battery; The preset battery is charged at a constant current according to the IC0 standard until the charging voltage reaches a preset charging limit voltage; The step of discharging the preset battery to a set capacity Q0 includes: The preset battery is discharged to the set capacity Q0 according to the 1C0 standard constant current.

3. The battery float charge parameter acquisition method according to claim 1, characterized in that: The step of obtaining the relationship between dV / dQ and the remaining capacity of a preset battery during discharge at a set temperature T0 includes: The preset battery is charged first with constant current and then with constant voltage until the charging voltage reaches a preset charging limit voltage and the cut-off current reaches a preset cut-off current; The preset battery is discharged at a constant current at a set temperature T0 until the discharge voltage of the preset battery reaches a preset discharge termination voltage, and the relationship between dV / dQ and the remaining capacity of the battery during the discharge process of the preset battery at the set temperature T0 is obtained.

4. The battery float charge parameter acquisition method according to claim 3, characterized in that: Also includes: Obtain the float charge current I of a preset battery at multiple set temperatures and set capacities Q0; Fitting the float charge current I of the preset battery at multiple set temperatures and set capacities Q0 to obtain a relationship between the float charge current I of the preset battery at the set capacity Q0 and temperature; According to the relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature, the floating charge current I of the preset battery at the set capacity Q0 and the selected temperature T is obtained. c Float charge current I c ; The relationship between the floating charge current I of the preset battery at the set capacity Q0 and the temperature is as follows: I=a(TT m ) 2 +I m ; Among them, a is the fitting coefficient, T m For any set temperature, I m The battery is set to the set temperature T m , set the float charge current under capacity Q0.

5. The method for obtaining battery float charge parameters according to any one of claims 1 to 4, characterized in that: Also includes: The preset self-discharge rate K(T0, Q0) of the preset battery at the set temperature T0 and the set capacity Q0 is used to obtain the preset float charge time of the preset battery at the set temperature T0 and the set capacity Q0 based on the following formula: t(T0,Q0)=K(T0,Q0)(T0-T max ) 2 ; t(T0, Q0) is the preset floating charge time of the preset battery at the set temperature T0 and the set capacity Q0, T max The maximum operating temperature of the preset battery.

6. A battery charging control method, characterized in that: include: Charge the preset battery to the set capacity Q0; A preset battery at a set temperature T0 and a set capacity Q0 is float charged, wherein the float charge current during the float charge process is obtained according to the battery float charge parameter acquisition method according to any one of claims 1 to 5.

7. The battery charging control method according to claim 6, characterized in that: The step of floating charging the preset battery at the set temperature T0 and the set capacity Q0 includes: The preset battery at the set temperature T0 and the set capacity Q0 is float charged for a preset float charge time, wherein the preset float charge time is obtained according to the battery float charge parameter acquisition method described in step 5.

8. A battery power management method, characterized in that: include: Get the current capacity Q of the battery m ; The current capacity of the battery Q m When the capacity of the battery is greater than a first set capacity threshold, constant voltage float charging is performed on the battery, and the float charging current used by the constant voltage float charging is configured to be obtained based on the battery float charging parameter acquisition method according to any one of claims 1 to 8; The current capacity of the battery Q m When the capacity of the battery is less than the second set capacity threshold, the battery is subjected to constant voltage discharge, and the cut-off current value of the constant voltage discharge is a float charge current value obtained based on the battery float charge parameter acquisition method according to any one of claims 1 to 8; Preferably, the first set capacity threshold is 15%-40%, and the second set capacity threshold is 60%-85%.

9. A battery, characterized in that: The battery comprises a stacked positive electrode sheet, a separator and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode material, and the positive electrode material comprises LiMn2O4, Li4Ti5O 12 、Li3V2(PO4)3、Li Fe 1-x W x PO4, LiW x Fe 1- x PO4、LiNi x Mn y Co 1-x-y O2 and Li Ni x Co y Al 1-x-y At least one of O2, wherein 0≤x≤1, 0≤y≤1, x+y≤1, and W is selected from at least one of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, V, and Ti; The negative electrode sheet includes a negative electrode material, and the negative electrode material includes at least one of graphite, mesophase carbon microbeads, silicon-carbon material, silicon-oxygen material, nano-silicon, and silicon alloy.

10. The battery according to claim 9, characterized in that The negative electrode material contains hard carbon, and the content of the hard carbon is 0-60%. Preferably, the content of the hard carbon is 5-30%.

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