Patent ID: 12224462

DESCRIPTION OF EMBODIMENTS

Hereinafter, an electrolyte supply system according to the present invention will be described with reference to the figures and embodiments.

Note that the following description exemplifies one embodiment of the present invention, and the present invention is not limited to the following description. The following description can be modified without departing from the gist of the present invention. In addition, in the present specification, control of the temperature of an electrolyte is referred to as “temperature control”.

<Subject to be Handled>

The electrolyte supply system of the present invention can properly meet the requirements of the use points and can be suitably used to store large quantities of electrolyte in liquid form that is reluctant to contact with air, has a relatively narrow storage temperature range of ±5° C. and is flammable, and to supply it to the use points.

<Configuration>

FIG.1illustrates a configuration of an electrolyte supply system1according to the present invention. The electrolyte supply system1is configured to include a receiving storage tank10connected to a gas-liquid separation device40through a receiving pipe44, a supply storage tank20connected to the receiving storage tank10through a connection pipe38, and a supply pipe32connected to the supply storage tank20. The supply pipe32extends to a use point92in an indoor space90.

Herein, the receiving storage tank10is a tank having a function of receiving an electrolyte from an external source, such as a lorry or the like. Furthermore, the supply storage tank20has a function of receiving the electrolyte from the receiving storage tank10and also has the supply pipe32to connect to the use point92. Therefore, it can be said that the receiving storage tank10cannot directly supply the electrolyte to the use point92, and the supply storage tank20does not have a function of directly receiving the electrolyte from an external source, such as a lorry or the like.

The use point92may be a point where the electrolyte is drawn from the supply pipe32through a branch pipe and used, and there may be a plurality of use points92in the indoor space90. Furthermore, the supply pipe32may be configured to return from the use point92to the supply storage tank20. The pipe extending from the use point92that is on the most downstream, as viewed from the supply storage tank20, is referred to as a return pipe32R. A thermometer32RT is disposed at the return pipe32R.

The receiving storage tank10and the supply storage tank20are installed outdoors and each have an internal volume of 5 m3or more. A heat insulating material or the like is disposed outside or inside the wall surface of each of the tanks. As a result, heat insulation is achieved. In addition, the tanks have a liquid-tight and air-tight structure.

The receiving storage tank10includes a breather valve16, a pressure monitoring unit14, and a liquid level sensor (not illustrated). The breather valve16supplies nitrogen gas from a nitrogen supply source (not illustrated) to prevent pressure decrease in the receiving storage tank10. That is, the inside of the receiving storage tank10is filled with nitrogen. Therefore, the electrolyte in the receiving storage tank10is not exposed to air (oxygen).

Although the pressure in the receiving storage tank10changes when the electrolyte is injected into the receiving storage tank10, transferred from the receiving storage tank10to the supply storage tank20, or the like, the pressure can be maintained at a slightly positive pressure above atmospheric pressure by the nitrogen supply source and the breather valve16. This slightly positive pressure serves to prevent the inflow of air from the outside. When an unexpected increase or decrease in internal pressure occurs, the pressure monitoring unit14opens a release valve (not illustrated) to discharge the gas in the receiving storage tank10or to introduce external air into the receiving storage tank10.

As described above, for the receiving storage tank10, detection of the liquid level (the level may be the height from the bottom surface of the receiving storage tank10) of the electrolyte contained therein and adjustment of the pressure within the space apart from the electrolyte can be achieved.

A circulation pipe18is disposed at the receiving storage tank10. The circulation pipe18is provided with a receiving storage tank pump12, a circulation pipe valve18v, and a temperature control device15.

The temperature control device15sets the temperature of the electrolyte in the receiving storage tank10to a predetermined temperature. The configuration thereof is not particularly limited, but includes at least a heating/cooling unit and a temperature sensor. The temperature sensor may be one configured to measure the temperature of the electrolyte in the receiving storage tank10.

The temperature setting of the temperature control device15is to be set in advance to a predetermined temperature, and the temperature control device15adjusts the temperature of the electrolyte that passes through the circulation pipe18. The predetermined temperature that is to be set may be changed by a controller50.

A connection pipe38connected to the supply storage tank20is provided between the temperature control device15and the circulation pipe valve18v. The connection pipe38is provided with a connection pipe valve38v.

A similar configuration to the above-described configuration is also arranged in the supply storage tank20, and is composed of a pressure monitoring unit24, a temperature control device25, a breather valve26, and a circulation pipe28. The supply storage tank20is provided with the circulation pipe28. The circulation pipe28is provided with a supply storage tank pump22and the temperature control device25.

As described above, the supply pipe32is connected to the supply storage tank20. A supply pump30is provided in the supply pipe32to supply the electrolyte into the supply pipe32.

The electrolyte supply system1may be provided with the controller50that controls the entire system. The controller50is connected to the respective pumps, the respective valves and the temperature control devices15and25, the liquid level sensors (not illustrated), the pressure monitoring units14and24, and the thermometer32RT. The controller50is capable of exchanging signals with these components. Note that the controller50may include more than one controller to be provided for each controlled object.

Specifically, the signals include those signaling activation and stoppage of each pump, opening and closing of each valve, temperature settings of the temperature control devices15and25, acquisition of the temperature of the electrolyte, acquisition of the current liquid level in the storage tanks, and the like. In addition, the controller50can also perform lot management of the electrolytes to be delivered.

<Operation>

Next, the operation of the electrolyte supply system1will be described.FIG.2shows a process flow for controlling the receiving storage tank10, andFIG.3shows a flow for controlling the supply storage tank20. The flows shown inFIGS.2and3are preferably executed simultaneously in the controller50.

As a general operation of the electrolyte supply system1, the electrolyte delivered by the lorry80or the like is received into the receiving storage tank10through the gas-liquid separation device40at a predetermined timing, the temperature is adjusted to a predetermined temperature, and then the electrolyte is transferred to the supply storage tank20so as to be supplied to the use point92.

Referring toFIG.2, when the control of the receiving storage tank10is started (step S100), a decision whether to terminate is made (step S102). When the process is terminated (Y branch in step S102), the control is ended (step S104). When the process is not terminated (N branch in step S102), the process proceeds to the subsequent process (step S106). Here, the decision whether to terminate may involve a manual stop or a stop due to some emergency. In addition, termination may be performed in the instance when the receiving storage tank10is empty and the electrolyte from the lorry80is being waited for.

In step S106, it is determined whether the electrolyte can be received in the receiving storage tank10. Here, it is determined whether a free space in the receiving storage tank10, the arrival of the lorry80on which the electrolyte is mounted, and the preparation for feeding the liquid to the receiving storage tank10, etc. are satisfactory. If it is determined that the receiving storage tank10can receive the electrolyte (Y branch in step S106), the liquid receiving operation is performed (step S108). Specifically, the circulation pipe valve18vis opened, the connection pipe valve38vis closed, and a receiving pump42and a receiving storage tank pump12are activated. InFIG.4, the flow of the electrolyte at this time is indicated by a thick line.

Referring toFIG.4, the electrolyte from the lorry80passes through the gas-liquid separation device40, so that bubbles generated in the electrolyte are removed. Then, the electrolyte passes through the receiving pipe44by the receiving pump42and is transferred to the receiving storage tank10. At this time, two valves are opened, which are a valve40vfor discharging gases from the gas-liquid separation device40and a valve82for filling the lorry80with nitrogen in a volume corresponding to a reduced volume of the electrolyte.

In addition, the connecting pipe valve38vis closed (indicated by the notation above the valve being filled with black, and the same shall apply hereinafter), and the circulation pipe valve18vis opened (indicated by the notation above the valve being shown in white while being indicated with a mark T, and the same shall apply hereinafter). Since the receiving storage tank pump12is activated, the temperature of the electrolyte in the receiving storage tank10is controlled to a predetermined temperature by the temperature control device15while the electrolyte circulates.

Referring back toFIG.2again, whether or not receiving is complete is determined by whether or not the receiving storage tank10is filled (step S110). This determination can be made by a liquid level sensor or the like in the receiving storage tank10(not illustrated inFIG.1). If the receiving is not completed (N branch in step S110), the process returns to step S108to continue to receive the electrolyte. If the reception is completed (Y branch in step S110), the process proceeds to the next step.

In the subsequent process (step S112), the receiving pump42is stopped. The valve40vand the valve82may also be closed. In step S106, if the receiving storage tank10is not ready to receive the electrolyte (N branch in step S106), the process jumps to this step S112.

Next, it is determined whether or not the temperature control of the electrolyte in the receiving storage tank10is completed (step S114). This state may be confirmed on the basis of temperatures measured by a thermometer disposed in the receiving storage tank10. Alternatively, if a state in which the difference between the temperature of the electrolyte flowing into the temperature control device15and the temperature of the electrolyte flowing out therefrom is sufficiently small continues for a predetermined time or longer, it may be determined that the temperature of the electrolyte in the receiving storage tank10is maintained at the set temperature.

If the temperature is not controlled (N branch in step S114), the temperature control is repeated. If the temperature has been controlled (Y branch in step S114), it is determined whether or not a liquid transfer request is made from the supply storage tank20(step S116). The liquid transfer request can be determined by the controller50on the basis of the remaining amount of the electrolyte in the supply storage tank20.

If the liquid transfer request is not made (N branch in step S116), the temperature control process (step S114) is repeated. If the liquid transfer request has been made (Y branch in step S116), a liquid transfer operation is performed (step S118). Specifically, the circulation pipe valve18vis closed, and the connection pipe valve38vis opened.

InFIG.5, the flow of the electrolyte in step S118is indicated by a thick line. The supply storage tank pump22is controlled to be constantly in an activated state on the supply storage tank20side. Note that the pump22may be activated periodically or depending on the temperature of the electrolyte in the supply storage tank20. The electrolyte flows from the inside of the receiving storage tank10, through the circulation pipe18, the temperature control device15, and the connection pipe38, to the supply storage tank20. Furthermore, the temperature of the electrolyte is controlled also in the supply storage tank20by the circulation pipe28, the supply storage tank pump22, and the temperature control device25.

Here, referring also toFIG.4, the receiving storage tank pump12is used for circulation of the electrolyte in the receiving storage tank10and is also used for transferring the electrolyte to the supply storage tank20. With such a configuration, if the receiving storage tank pump12is activated, the electrolyte does not stay in the pipe that extends from the receiving storage tank10toward the supply storage tank20.

If the circulation pump and the liquid transfer pump are separate components, when the electrolyte is transferred from the receiving storage tank10to the supply storage tank20using the liquid transfer pump, the electrolyte would result in being suspended in the pipe extending from the receiving storage tank10to the supply storage tank20without flowing until the next transfer of the electrolyte. The temperature of the residual electrolyte may deviate from an appropriate temperature range due to a lapse of time.

Then, the electrolyte whose temperature is not controlled would be transferred to the supply storage tank20. Just before the electrolyte is transferred to the supply storage tank20, the amount of the electrolyte in the supply storage tank20is reduced. Thus, there is a possibility that the temperature of the electrolyte in the supply storage tank20would change due to the temperature-uncontrolled electrolyte in the pipe extending from the receiving storage tank10toward the supply storage tank20.

When viewed from the use point92side, this circumstance signifies that an electrolyte whose temperature has changed is supplied. On the other hand, a configuration that can also be used for transferring the electrolyte to the supply storage tank20can be made by arranging the receiving storage tank pump12to be in the middle of the circulation pipe18as shown inFIG.4andFIG.5and by operating the circulation pipe valve18v. With this configuration, it is possible to reduce such a residual electrolyte like that described above.

Referring back toFIG.2again, the liquid transfer operation is performed (step S118). As a result, the electrolyte is transferred from the receiving storage tank10to the supply storage tank20, and it is determined whether the liquid transfer is completed (step S120). This determination may be made on the basis of any of factors including the liquid level in the receiving storage tank10, the liquid level in the supply storage tank20, and the liquid transfer amount.

If the liquid transfer is not completed (N branch in step S120), the liquid transfer operation is continued (step S118). If the liquid transfer is completed (Y branch in step S120), the subsequent liquid transfer stopping operation is performed (step S122). Specifically, the receiving storage tank pump12is stopped and the connection pipe valve38vis closed. The supply storage tank pump22may continue to be activated because the temperature control of the electrolyte in the supply storage tank20is continued. Then, the process returns to the decision whether to terminate (step S102).

Before returning to step S102, calculation for the lot management may be performed (step S124). This calculation will be described later. In the figure, this calculation is indicated by “LOT CALCULATION”. In the lot calculation, the lot number and the ratio of the electrolyte constituting the electrolyte in the supply storage tank20are calculated and recorded, so that the lots are managed. Here, the lot number is associated with at least the reception date and time of the electrolyte received in the receiving storage tank10. The lot number may also be associated with a quantity of the receiving electrolyte.

FIG.6shows the state in step S122. Since the supply storage tank pump22is activated and the connection pipe valve38vis closed, the temperature of the electrolyte in the supply storage tank20is controlled to be a predetermined temperature by the temperature control device25while the electrolyte is made to flow through the circulation pipe28.

Next, with reference toFIG.3, control of the supply storage tank20will be described. When the process starts (step S200), a decision whether to terminate is performed (step S202). When the process is terminated (Y branch in step S202), the process is stopped (step S204). When the process is not terminated (N branch in step S202), the process proceeds to the subsequent process.

Next, the remaining amount of the electrolyte in the supply storage tank20is checked (step S206and step S210). First, when the remaining amount is less than a predetermined threshold value Th1 (Y branch in step S206), the lorry80makes a delivery request of the electrolyte (step S208). Since the electrolyte supply system1handles a large volume of the electrolyte, the pace of consumption, the time lag from the delivery request till the actual delivery, and the amount of time for the temperature control in the receiving storage tank10are taken into consideration in advance and the delivery request is then made. Note that the delivery request may be directly made by the controller50, and may be indirectly made by, for example, displaying a timing of the delivery request to an operator.

When the remaining amount is less than a predetermined threshold value Th2 (Y branch in step S210), a liquid transfer request is made (step S212). When the liquid transfer request is made, the electrolyte is transferred from the receiving storage tank10to the supply storage tank20(step S118inFIG.2). Note that the threshold value Th1 is larger than the threshold value Th2, and when the remaining amount checking steps (step S206and step S210) are both N branches, the process skips to the subsequent step of step S212.

Next, the presence or absence of a request from the use point (denoted as “U.P.” inFIG.3)92is determined (step S214). At the use point92, when the electrolyte is consumed, a use request is made to the electrolyte supply system1. If there is a request from the use point92(Y branch in step S214), the supply pump30(denoted as “P30” inFIG.3) is activated (step S216). If there is no request (N branch in step S214), the supply pump30is not activated (stopped: step S218).

FIG.7shows a state in which the electrolyte is supplied from the supply storage tank20to the use point92and returns to the supply storage tank20through the return pipe32R. At this time, the electrolyte is also circulated in the circulation pipe28, so that the temperature of the electrolyte in the supply storage tank20is maintained at a constant temperature by the temperature control device25.

Returning back toFIG.3again, if the operation of the supply pump30(step S216or step S218) is stopped, the process returns to the decision whether to terminate (step S202).

Next, the lot management of the electrolyte will be described with reference toFIG.8. This is an example process of step S124inFIG.2. InFIG.8, (a) and (c) show the receiving storage tank10, and (b) and (d) show the supply storage tank20. In addition, (a) and (b) illustrate respective cases at the same timing, and (c) and (d) also illustrate respective cases at the same timing but separate from that of (a) and (b).

First, referring toFIG.8(a)andFIG.8(b), V1 is the volume of the receiving storage tank10and V2 is the volume of the supply storage tank20. Furthermore, it is assumed that at least “a (a is a real number smaller than 1)” times the volume of the receiving storage tank10remains in the receiving storage tank even after the electrolyte has been transferred to the supply10storage tank20, and that at least “c (c is a real number smaller than 1)” times the supply storage tank20remains in the supply storage tank20even after the electrolyte has been transferred to the use point92.

Then, when the electrolyte of the n-th lot is received in the receiving storage tank10, the electrolytes of the lot numbers up to n−1 remain therein. The remaining electrolytes of the lot numbers up to n−1 are denoted by R (n−1), and the remaining amount of the electrolytes of the lot numbers up to n−1 is denoted by “aV1R(n−1)”. The superscripts do not represent a multiplier, but rather a lot number. The same applies hereinafter. Therefore, the input amount of the electrolyte of the n-th lot is expressed as “(1−a)V1n)”. This means that the electrolyte of the n-th lot is present in a volume of “(1−a)V1)”.

InFIG.8(a), the volume of the electrolyte in the receiving storage tank10is denoted by “V1Σ(n)”. The total amount of electrolyte in the receiving storage tank10is expressed by the sum of the electrolyte of the n-th lot and the remaining electrolytes of the lot numbers up to n−1. This matter can be expressed by the mathematical formula (1).

[Mathematical Formula 1]
V1Σ(n)=(1−a)V1n+αV1R(n−1)(1)

InFIG.8(b), there are the remaining electrolytes of the lot numbers up to n−1. When these electrolytes are denoted by S(n−1), the amount thereof is expressed as “cV2S(n−1)”. This indicates that there are the remaining electrolytes of the lot numbers up to n−1 in an amount that is c times the volume V2.

InFIG.8(a), when the temperature adjustment is completed in the receiving storage tank10, as shown inFIG.8(c), the electrolyte in an amount of (1−a) V1 is transferred to the supply storage tank20. Therefore, the amount of the electrolyte to be transferred is expressed as “(1−a)V1Σ(n)”. This amount is the transferred liquid of the n-th lot.

As shown inFIG.8(d), the electrolyte in the supply storage tank20is the sum of the electrolyte of the n-th lot that has been transferred and the remaining electrolytes of the lot numbers up to n−1. This means that the electrolyte is composed mainly of the electrolyte of the n-th lot. When this matter is denoted by L (n), the mathematical formula (2) is obtained.

[Mathematical Formula 2]
L(n)=(1−a)V1Σ(n)+c V2S(n−1)(2)

If UL (n) is the consumed amount, then UL(n)=(1−c)L(n) is defined. The remaining amount of the electrolyte after the electrolyte of the n-th lot has been used is “cV2S(n)”. These matters are expressed by the mathematical formulas (3) and (4), respectively.

[Mathematical Formula 3]
UL(n)=(1−c)L(n)=(1−c){(1−a)V1Σ(n)+c V2S(n−1)}  (3)
[Mathematical Formula 4]
cV2S(n)=c{(1−a)V1Σ(n)+cV2S(n−1)}  (4)

As described above, the electrolyte of the n-th lot can be managed on the basis of the sum of first, the sum of the amounts of the electrolytes in the receiving storage tank10, calculated by adding the remaining amount of the electrolytes of the lot numbers up to n−1 and the amount of the electrolyte of the new n-th lot therein, and second, the remaining amount of the electrolytes of the lot numbers up to n−1 in the supply storage tank20, as expressed by the mathematical formula (2). If n is large, the calculation will be enormous. In practice, however, the remaining amounts of the electrolytes of the lot before the third generation will be very small, and so such amounts can be ignored and the calculation will not be very complicated. Therefore, since the delivered electrolyte is consumed in order, even when the calculation is enormous, the management is easy.

As described above, the date and time when the electrolyte of the n-th lot number is input into the receiving storage tank10, the date and time when the electrolyte is transferred to the supply storage tank20, and the time period during which the electrolyte was supplied from the supply storage tank20to the use point92are accurately recorded. Consequently, it is possible to know how much electrolyte of which lot was contained in the electrolyte supplied from the supply storage tank20and how much of this electrolyte was used. Therefore, it is also possible to know how much the electrolyte of which lot was used in a product whose production date is known, and it is possible to perform the lot management of electrolytes.

FIG.9is a schematic view illustrating cases where the supply storage tanks20ofFIG.1are arranged in parallel. Referring toFIG.9(a), a supply storage tank100and a supply storage tank110are arranged in parallel and connected to a switching valve120through supply pipes (102and112, respectively). An electrolyte is supplied to a use point92through a pipe125that is connected to the switching valve120.

A switching valve122is disposed at the end of the use point92, and return pipes (102R and112R, respectively) to the respective supply storage tanks100and110are provided. Note that a pump is omitted in the figure, and the switching valves120and122each include a white circle representing the open side and a black circle representing the closed side.

Referring toFIG.9(a), the electrolyte is now supplied from the supply storage tank110. The electrolyte returns to the supply storage tank110through the route of the supply pipe112, the switching valve120, the pipe125, the switching valve122, and the return pipe112R.

FIG.9(b)shows a case where the switching valves120and122are operated to switch to the supply storage tank100. At this time, the electrolyte from the supply storage tank110remains in the pipe125(a portion indicated by a chain line). The electrolyte returns to the supply storage tank100through the return pipe102R.

That is, the electrolyte from the supply storage tank110of a different system returns to the supply storage tank100. The same occurs in the supply storage tank110where the electrolyte from the supply storage tank100of a different system is allowed to return to the supply storage tank110. When the electrolyte returns to a supply storage tank of a different system, it is not easy to clarify the lot management as in the above-described mathematical formulas (2), (3), and (4). Specifically, the electrolyte that was delivered as that of the previous lot remains as a residual component.

Furthermore, referring toFIG.9(b), in the return pipe112R (a part indicated by a broken line), which returns to the supply storage tank110, the electrolyte of the previous lot is left, and the temperature control is not performed thereon until the next supply from the supply storage tank110is performed. If the state outside the temperature range continues for a longer period of time, the quality of the electrolyte will also be compromised, and an electrolyte having poor quality will be supplied to the use point92.

On the other hand, by arranging the receiving storage tank10and the supply storage tank20in series as in the present invention, it is possible to prevent the electrolyte from staying in the return pipe32R or in the pipe from the receiving storage tank10to the supply storage tank20. In addition, since the electrolytes of different systems are not mixed and the electrolyte is consumed in the order in which the electrolyte is delivered, the lot management becomes easy.

As described above, the electrolyte supply system1according to the present invention has a configuration in which the receiving storage tank10and the supply storage tank20are arranged in series. Thus, it is possible to adjust the temperature of a large amount of an electrolyte while constantly supplying the electrolyte to the use point92. Therefore, even when an electrolyte has a narrow storage temperature range, the electrolyte can be controlled to be at a predetermined temperature and can be supplied at any time, 24 hours a day. In addition, lot management is possible, and the material history can be traced when a defective product occurs.

Secondary batteries can be manufactured by a known method using the electrolyte supplied by the electrolyte supply system1according to the present invention. As an example, a positive electrode and a negative electrode are prepared by bonding a positive electrode material and a negative electrode material to respective base materials and increasing the densities thereof by a press or the like. A separator is sandwiched between these electrodes to form an assembly, and a plurality of the resulting assemblies is stacked. The resulting laminate is placed in a can, which serves as a container of a battery. Then, the electrolyte supplied by the electrolyte supply system1according to the present invention is injected thereinto, and a lid is welded thereon. The lid and the container serve as respective electrodes of the battery.

INDUSTRIAL APPLICABILITY

The electrolyte supply system according to the present invention can be suitably used when a large amount of an electrolyte for a lithium ion-based battery is stored and supplied.

REFERENCE SIGNS LIST

1electrolyte supply system10receiving storage tank12receiving storage tank pump14pressure monitoring unit15temperature control device16breather valve18circulation pipe18vcirculation pipe valve20supply storage tank22supply storage tank pump24pressure monitoring unit25temperature control device26breather valve28circulation pipe30supply pump32supply pipe32R return pipe32RT thermometer38connection pipe38vconnection pipe valve40gas-liquid separation device40vvalve42receiving pump44receiving pipe50controller80lorry82valve90indoor space92use point100,110supply storage tank102,112supply pipe120,122switching valve102R,112R return pipe125pipe