Lithium battery unit and lithium battery assembly

Abstract

The invention belongs to the technical field of battery detection, and particularly relates to a lithium battery unit and a lithium battery assembly, and the lithium battery unit comprises a battery unit and a battery module M. The battery module M comprises a first battery pack, and the first battery pack is connected with a plurality of battery units in series; a second battery pack in which a plurality of battery cells are connected in series, the first battery pack being connected in parallel with the second battery pack; the monitoring unit is used for monitoring the state of the battery module M; and a control unit for controlling charging and discharging of the battery module, the present invention is advantageous in that by detecting a determined value of a current change due to a sudden increase in voltage during overcharging, overcharging can be avoided, circuit configuration can be reduced, and battery use safety can be improved using a simple sensor element.

Description

Technical Field

[0001] The invention belongs to the technical field of battery detection, and in particular relates to a lithium battery unit and a lithium battery assembly. Background Art

[0002] Continuing to charge a lithium battery for a long time after it is fully charged will cause an imbalance in the internal chemical reaction and cause overcharging. Overcharging will increase the internal pressure of the battery. Long-term accumulation may cause the battery active substances to fall off and reduce the battery capacity. Long-term overcharging may also cause more serious physical damage, such as battery swelling or deformation. In extreme cases, overcharging may even cause the battery to explode. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a lithium battery assembly to solve the problem of battery overcharging and other problems.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: A lithium battery unit and a lithium battery assembly, comprising a battery unit and a battery module M, wherein the battery module M comprises a first battery group, wherein the first battery group connects a plurality of battery units in series; a second battery group, wherein the second battery group connects a plurality of battery cells in series, and the first battery group and the second battery group are connected in parallel; A monitoring unit, used to monitor the status of the battery module M; and a control unit, for controlling the charging and discharging of the battery module; The monitoring unit includes a first current sensor 11A for measuring the total current IA of the first battery pack; a second current sensor 11B for measuring the total current IB of the second battery pack; The control unit calculates a determination value according to the total current IA and the total current IB, and determines whether overcharging occurs according to the determination value; The control unit calculates the slope of the current ratio of the total current IA to the total current IB as a judgment value, and judges the occurrence of overcharging according to the state that the slope of the current ratio is above a threshold value and is maintained for a predetermined time.

[0005] Furthermore, the battery cells in the first battery group and the battery cells in the second battery group both include a positive electrode layer, a negative electrode layer, and an electrolyte layer arranged between the positive electrode layer and the negative electrode layer. The outside of the positive electrode layer is covered with a positive electrode collector for collecting current in the positive electrode layer, the outside of the negative electrode layer is covered with a negative electrode collector for collecting current in the negative electrode layer, and the outside of the battery cell is provided with a shell.

[0006] Furthermore, the electrolyte layer includes an inorganic solid electrolyte.

[0007] Furthermore, the predetermined time is 1 second or longer.

[0008] Furthermore, the control unit includes an electronic control unit and a power control unit, wherein the electronic control unit instructs the power control unit to charge or discharge based on external charging and discharging requirements and the status of the first battery group and the second battery group obtained from the monitoring unit, and the power control unit receives power from the power supply during charging and supplies power to the load during discharging.

[0009] Further, the control unit calculates a determination value based on the total current IA and the total current IB, determines the occurrence of overcharging based on the determination value, and stops charging.

[0010] Furthermore, the multiple battery cells are connected in series, and the multiple battery cells are stacked along the X-axis direction.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The control unit controls the charging and discharging of the battery module based on the data obtained from the monitoring unit. The monitoring unit includes a current sensor and a voltage sensor, which are respectively used to measure the total current of each battery pack and the total voltage of the battery module. The control unit can calculate the difference in current ratio or current integral value to determine whether overcharging has occurred and stop charging when necessary. By detecting the determined value of the current change caused by the sharp increase in voltage during overcharging, overcharging can be avoided using simple sensor elements, reducing circuit structure and improving battery safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the principle of the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the battery unit in the present invention.

[0013] The reference numerals in the drawings of the specification include: 1. Positive electrode layer; 2. Negative electrode layer; 3. Electrolyte layer; 4. Positive electrode collector; 5. Negative electrode collector; 6. Outer casing; 10A, first battery pack; 10B, second battery pack; 11. Monitoring unit; 11A, first monitoring unit; 11B, first monitoring unit; 12. Control unit; 13. Power supply; 14. Load. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: It should be noted that the same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0015] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0016] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention. Example

[0017] like Figure 1-Figure 2 As shown, the battery cell includes a positive electrode layer 1, a negative electrode layer 2, an electrolyte layer 3 located between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode collector 4 for collecting current of the positive electrode layer 1, a negative electrode collector 5 for collecting current of the negative electrode layer 2, and an outer packaging body 6 for storing the collector. In addition, in the battery pack, multiple battery cells are connected in series, and multiple battery cells are stacked along the X-axis direction.

[0018] The lithium battery assembly includes a battery module M, which includes a first battery group 10A and a second battery group 10B, wherein the first battery group 10A and the second battery group 10B each include a plurality of battery cells connected in series, and the first battery group 10A is connected in parallel with the second battery group 10B. In addition, the lithium battery assembly also includes a monitoring unit 11, which is used to monitor the status of the first battery group 10A and the second battery group 10B. The monitoring unit 11 includes a first current sensor 11A and a second current sensor 11B, wherein the first current sensor 11A is used to measure the total current IA of the first battery group 10A, and the second current sensor 11B is used to measure the total current IB of the second battery group 10B.

[0019] In addition, the lithium battery assembly as shown in the figure also includes a control unit 12, which is used to control the charging and discharging of the battery module M. The control unit 12 includes a first electronic control unit 121 and a second electronic control unit 122. The first electronic control unit 121 instructs (such as start instructions and stop instructions) the second electronic control unit 122 to charge / discharge based on a demand R from the outside (such as a charging demand and a discharging demand) and a battery status (the status of the first battery pack 10A and the second battery pack 10B) obtained from the monitoring unit 11. The second electronic control unit 122 receives power from the power supply 13 during charging and supplies power to the load 14 during discharging. The control unit 12 calculates a determination value based on the total current IA and the total current IB, determines the occurrence of overcharging based on the determination value, and stops charging.

[0020] By calculating the determination value based on the total current IA and the total current IB, overcharging can be avoided using a simple sensor element, and there is no need to provide a voltage detection line for each battery cell, so the sensor element can be simplified.

[0021] By focusing on the occurrence of a sharp rise in voltage during overcharging and calculating the changes in the total current IA and the total current IB caused by the sharp rise in voltage as the judgment value, the sensor element is simplified. The battery cell is charged and tested using an inorganic solid electrolyte (sulfide solid electrolyte) as the solid electrolyte. When the SOC (state of charge) of the battery cell becomes higher, the voltage of the battery cell rises sharply. When a commonly used liquid electrolyte is used, the sharp voltage rise may not be confirmed because the liquid electrolyte decomposes oxidatively before the battery cell voltage rises sharply. When a liquid electrolyte with a high oxidative decomposition voltage is used, it is estimated that the voltage rises sharply. In addition, the cause of the sharp rise in the battery cell voltage is estimated to be the occurrence of excessive voltage.

[0022] Furthermore, among the battery cells included in the battery pack, examples of battery cells that may be overcharged include battery cells that deteriorate over time due to an accelerated charge / discharge rate. Specifically, a battery cell whose capacity decreases due to charge / discharge may be in an overcharged state during charging, and by using a determination value calculated based on the total current IA and the total current IB (a determination value based on a current change caused by a sharp increase in voltage during overcharging), a lithium battery assembly that can avoid overcharging using a simple sensor element can be obtained.

[0023] The control unit 12 includes a first electronic control unit 121 and a second electronic control unit 122 for monitoring battery information obtained by the unit to determine the start, continuation and stop of charging (preferably, charging and discharging).

[0024] The first electronic control unit 121 is used to determine the start, continuation and stop of charging (preferably charging and discharging) based on the battery information obtained from the monitoring unit. The first electronic control unit 121 generally includes a CPU (central processing unit), a memory, and an input / output port for inputting and outputting various signals. The memory includes, for example, a ROM (read-only memory), a RAM (random access memory) and a rewritable non-volatile memory. Various determinations are performed by the CPU by a program stored in the memory.

[0025] The first electronic control unit 121 includes at least a calculation part and a determination part, as a processing block configured to implement this function, the calculation part is set to calculate the determination value based on the total current IA and the total current IB, and in addition, the determination part obtains the total current IA that changes with time from the first current sensor 11A, and obtains the total current IB that changes with time from the second current sensor 11B.

[0026] The calculation part calculates the current ratio of the total current IA and the total current IB as the judgment value. In this case, the determination part judges the occurrence of overcharging based on the state that the value of the current ratio is equal to or greater than the threshold value and is maintained for a predetermined time. When the first battery pack 10A and the second battery pack 10B do not contain abnormal cells (battery cells that may be overcharged), IB / IA is always 1.

[0027] When the first battery pack 10A includes an abnormal battery, and the second battery pack 10B does not include an abnormal battery, the total current IA will be lower than the total current IB due to a sharp voltage rise in the abnormal battery, and when overcharge occurs, the value of the current ratio (IB / IA) will be greater than 1, and thereafter, the value of the current ratio (IB / IA) increases with time. Therefore, the occurrence of overcharge can be judged based on the situation where the value of the current ratio is equal to or greater than the threshold value and is maintained for a predetermined time.

[0028] The calculation part can calculate the slope of the current ratio of the total current IA and the total current IB as the judgment value, and the determination part preferentially judges the occurrence of overcharging based on the situation that the slope of the current ratio is a threshold value or greater and is maintained for a predetermined time. When the first battery group 10A and the second battery group 10B do not contain abnormal batteries (battery cells that may be overcharged), the slope of IB / IA is always 0.

[0029] When the first battery pack 10A includes an abnormal battery and the second battery pack 10B does not include an abnormal battery, due to the sharp voltage increase in the abnormal battery, the total current IA will be lower than the total current IB, and when overcharging occurs, the slope of the current ratio (IB / IA) will be higher than 0. Therefore, the occurrence of overcharging can be determined based on the situation where the slope of the current ratio is equal to or greater than the threshold and is maintained for a predetermined time.

[0030] The threshold value of the slope of the current ratio is not particularly limited. When the time unit is "seconds", the threshold value is, for example, 0.5 or more, 1 or more, or 2 or more. The slope of the current ratio can be determined as the amount of change in the current ratio within a unit time (for example, 1 second). In addition, the predetermined time is not particularly limited. For example, it can be 1 second or more, 5 seconds or more, or 1 minute or more. In addition, assuming that the first battery pack 10A contains an abnormal battery or the second battery pack 10B contains an abnormal battery, when overcharging occurs, the threshold value is IB. <IA<1。

[0031] The calculation part can calculate the absolute value of the difference between the integral value of the total current IA and the integral value of the total current IB as the judgment value, and the determination part preferably uses the absolute value as a threshold value or greater, and the constant increase value of the integral value of the total current IA and the integral value of the total current IB during the period from the base point to the threshold value to judge the occurrence of overcharging. When the first battery group 10A and the second battery group 10B do not contain abnormal batteries (battery cells that may be overcharged), the difference between the integral value of the total current IA and the integral value of the total current IB is 0.

[0032] When the first battery pack 10A includes an abnormal battery, and the second battery pack 10B does not include an abnormal battery, the total current IA will be lower than the total current IB due to a sharp voltage rise in the abnormal battery, the integral value of the total current IA will be relatively low, and the integral value of the total current IB will be relatively high. Therefore, in some cases, the occurrence of overcharging can be judged based on the difference between the integral values ​​being greater than or equal to the threshold value, and the threshold value of the difference (absolute value) between the integral values ​​is not particularly limited. When the initial battery capacity is regarded as 100%, the threshold value is, for example, 10% or more, 20% or more, or 50% or more. The battery capacity taking into account the deterioration due to charging / discharging can be regarded as 100% instead of the initial battery capacity.

[0033] The second electronic control unit 122 is used to start, continue and stop charging of the battery module based on the determination of the first electronic control unit 121. For the second electronic control unit 122, it can be a similar structure to that in a conventional lithium battery assembly. In addition, the lithium battery assembly of the present invention includes a display unit, which is used to display a warning when overcharging occurs. Examples of the display unit include a liquid crystal display.

[0034] The battery module includes a first battery group 10A including a plurality of battery cells connected in series, and a second battery group 10B including a plurality of battery cells connected in series.

[0035] The battery cell includes a positive electrode layer 1, a negative electrode layer 2, an electrolyte layer 3 located between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode collector 4 for collecting current from the positive electrode layer 1, a negative electrode collector 5 for collecting current from the negative electrode layer 2, and an outer packaging body 6 for storing the collector. In addition, in the battery pack, multiple battery cells are connected in series, and multiple battery cells are stacked along the X-axis direction.

[0036] The positive electrode layer 1 contains a positive electrode active material, and further contains at least one of an electrolyte, a conductive material, and a binder as needed. The type of the positive electrode active material is not particularly limited, for example, an oxide active material, the oxide active material includes rock salt bed type active materials such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium vanadium oxide, and lithium nickel cobalt manganese oxide; spinel type active materials such as spinel type lithium manganese oxide, lithium titanate, and lithium nickel manganese oxide; and olivine type active materials such as lithium iron phosphate, lithium manganese phosphate, lithium nickel phosphate, and lithium cobalt phosphate.

[0037] As the electrolyte used for the positive electrode layer 1, the same material as the electrolyte used for the electrolyte layer 3 described later can be used. The conductive material includes carbon materials such as acetylene black, Ketjen black, carbon fiber, carbon nanotube and carbon nanofiber. Examples of the binder include fluorine-based binders such as polyvinylidene fluoride.

[0038] The positive electrode layer 1 includes at least an anode active material, including at least one of an electrolyte, a conductive material and an adhesive. The anode active material includes a carbon active material such as graphite and a metal active material such as Si, Sn, In and Al. The electrolyte, conductive material and adhesive may be the same as those described in the above-mentioned cathode layer.

[0039] The electrolyte in the electrolyte layer 3 may be an inorganic solid electrolyte, a solid polymer electrolyte, an electrolyte solution (liquid electrolyte), or a semi-solid electrolyte (clay-type electrolyte), among which an inorganic solid electrolyte is preferred. The reason is that it is unlikely to cause oxidative decomposition due to overcharging. That is, the battery cell in the present disclosure is preferably an all-solid battery cell including a solid electrolyte layer of an inorganic solid electrolyte, and the oxidative decomposition voltage of the electrolyte is, for example, 5V or 30V or higher.

[0040] Inorganic solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes and halide solid electrolytes. Sulfide solid electrolytes include solid electrolytes of Li element, X element (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga and In) and S element. In addition, sulfide solid electrolytes also include at least one of o element and halogen element. Halogen elements include F element, Cl element, Br element and I element.

[0041] The sulfide solid electrolyte may be a glass-type solid electrolyte, a glass-ceramic-type solid electrolyte, or a crystalline solid electrolyte. In addition, the sulfide solid electrolyte includes a crystalline phase having high ionic conductivity, examples of which include a Thio-LISICON-type crystalline phase, an LGPS-type crystalline phase, and an algae-type crystalline phase.

[0042] Examples of oxide solid electrolytes include solid electrolytes of Li element, Y element (Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W and S) and O element. Specific examples of oxide solid electrolytes include garnet-type solid electrolytes such as perovskite-type solid electrolytes such as lanthanum titanium oxide, sodium superion conductor-type solid electrolytes, and examples of nitride solid electrolytes include lithium nitride. Examples of halide solid electrolytes include LiCl, LiI and LiBr.

[0043] The positive electrode current collector and the negative electrode current collector may be common current collectors. In addition, the type of the outer casing 6 is not particularly limited, and may be a laminated outer casing or a box-type outer casing.

[0044] The type of battery cell is not particularly limited, but a lithium-ion battery is preferred.

[0045] The battery module includes a first battery pack 10A and a second battery pack 10B as a battery pack, and the battery pack includes a plurality of battery cells connected in series. The number of battery cells in the battery pack is usually 2 or more, and the number of battery cells in the first battery pack 10A and the number of battery cells in the second battery pack 10B can be the same or different.

[0046] The total voltage (fully charged) of the battery pack may be greater than 5 V or less than 400 V. The total voltage (fully charged) of the first battery pack 10A and the total voltage (fully charged) of the second battery pack 10B may be the same or different.

[0047] The first battery group 10A and the second battery group 10B may be connected in parallel. In addition to the first battery group 10A and the second battery group 10B, one or more other battery groups may be connected in parallel.

[0048] The lithium battery assembly is provided with a monitoring unit 11, which is used to monitor the status of the first battery group 10A and the second battery group 10B. The monitoring unit includes a first current sensor 11A, which is used to measure the total current IA of the first battery group 10A, and a second current sensor 11B, which is used to measure the total current IB of the second battery group 10B. When the battery module includes one or more other battery groups connected in parallel in addition to the first battery group 10A and the second battery group 10B, the monitoring unit 11 includes current sensors for measuring the total current of the other battery groups. In addition, the monitoring unit includes a voltage sensor (total voltage sensor), which is used to measure the total voltage V of the battery module. The current sensor and the voltage sensor can be commonly used sensors.

[0049] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A lithium battery unit and a lithium battery assembly, including a battery module M and a battery unit, characterized in that: The battery module M comprises a first battery group (10A), wherein the first battery group (10A) connects a plurality of battery cells in series; A second battery group (10B) comprises a first battery group (10A) and a plurality of battery cells connected in series, wherein the first battery group (10A) and the second battery group (10B) are connected in parallel; A monitoring unit (11), used for monitoring the status of the battery module M; and a control unit (12), used for controlling the charging and discharging of the battery module M; The monitoring unit (11) comprises a first current sensor 11A, used for measuring the total current IA of the first battery group (10A); a second current sensor 11B, used for measuring the total current IB of the second battery group (10B); The control unit (12) calculates a determination value according to the total current IA and the total current IB, and determines whether overcharging occurs according to the determination value; The control unit (12) calculates the slope of the current ratio of the total current IA to the total current IB as a judgment value, and the control unit (12) judges the occurrence of overcharging according to the state that the slope of the current ratio is above a threshold value and is maintained for a predetermined time.

2. The lithium battery unit and lithium battery assembly according to claim 1, characterized in that: The control unit (12) comprises an electronic control unit (121) and a power control unit (122), a power source (13), and a load (14). The electronic control unit (121) instructs the power control unit (122) to charge or discharge based on external charging and discharging requirements and the states of the first battery group (10A) and the second battery group (10B) obtained from the monitoring unit (11). The power control unit (122) receives power from the power source (13) during charging and supplies power to the load (14) during discharging.

3. The lithium battery unit and lithium battery assembly according to claim 1, characterized in that: The predetermined time is 1 second or longer.

4. The lithium battery unit and lithium battery assembly according to claim 1, characterized in that: The control unit (12) calculates a determination value based on the total current IA and the total current IB, determines the occurrence of overcharging based on the determination value, and stops charging.

5. The lithium battery unit and lithium battery assembly according to claim 1, characterized in that: The battery cells in the first battery group (10A) and the battery cells in the second battery group (10B) both comprise a positive electrode layer (1), a negative electrode layer (2), and an electrolyte layer (3) disposed between the positive electrode layer (1) and the negative electrode layer (2); the positive electrode layer (1) is externally covered with a positive electrode collector (4) for collecting current of the positive electrode layer (1); the negative electrode layer (2) is externally covered with a negative electrode collector (5) for collecting current of the negative electrode layer (2); and the battery cells are externally provided with a casing (6).

6. The lithium battery unit and lithium battery assembly according to claim 5, characterized in that: The electrolyte layer (3) includes an inorganic solid electrolyte.

7. The lithium battery unit and lithium battery assembly according to claim 6, characterized in that: The plurality of battery cells are connected in series, and the plurality of battery cells are stacked along the X-axis direction.

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