CN107959038B - A flow battery pulse charging and discharging system and method for improving electrolyte utilization - Google Patents

Abstract

The invention discloses a flow battery pulse type charging and discharging system and method for improving the utilization rate of electrolyte, and belongs to the field of new energy storage. When an intermittent on-off pulse signal is input to the pulse timing power switch, the charging and discharging system is enabled to change into intermittent charging instead of continuously charging electrolyte in the flow battery. And in the period of no charging, the circulating pump still continuously operates until the charging cut-off voltage is reached, the charging process is completed, and the discharging process is entered. In the discharging process, the pulse type timing power switch is intermittently turned on and off, and the electrolyte is kept to be intermittently discharged until the discharge cut-off voltage is reached, so that the discharging process is completed. Thereby constituting a charge-discharge cycle. The invention can not only achieve the contradiction between the equilibrium concentration polarization and the pumping work, but also reduce the difference of the charge states of the electrolyte between the galvanic pile and the liquid storage tank and improve the utilization rate of the electrolyte.

Description

A flow battery pulse charging and discharging system and method for improving electrolyte utilization

technical field

The invention belongs to the field of new energy storage, and in particular relates to a flow battery pulse charging and discharging system and method for improving the utilization rate of electrolyte.

Background technique

In recent years, with the development of human production and the continuous improvement of living standards, the demand for energy is also increasing. However, limited non-renewable energy cannot guarantee the sustainable development of human beings, and the traditional energy supply structure dominated by fossil energy has increasingly become a bottleneck restricting social and economic development. Therefore, optimizing the energy application structure and developing renewable new energy have become the focus of common attention and research in the world.

However, the use of new energy is limited by time and the external environment, resulting in poor stability and continuity, and will also have a serious impact on the power grid. Therefore, it is necessary to configure corresponding energy storage equipment in the power grid system, store electric energy when the energy is sufficient, and connect to the grid for power generation when the energy is insufficient, adjust the contradiction between supply and demand of energy, realize peak shaving and valley filling, and then realize efficient energy utilization and stable continuity power output.

Large-scale and high-efficiency energy storage technology is the key technology to realize the large-scale utilization of renewable energy power generation. Redox flow batteries are currently one of the most suitable large-scale energy storage technologies for the field of renewable new energy. The concept of redox flow battery was first proposed by L.H. Thaller. In recent years, its research and development, engineering and industrialization have also made important progress, showing great application prospects in the field of large-scale energy storage technology. Unlike traditional energy storage systems, the active materials of an oxygen flow battery are dissolved in its electrolyte and stored in an external liquid storage tank. The traditional flow battery structure uses two circulating pumps to transfer the positive and negative electrolytes from the liquid storage tank to the stack area of the battery. When the electrolyte flows through the electrode area, the exchange between chemical energy and electrical energy occurs on the electrode surface. Mutual conversion process, so as to realize the mutual conversion between electrical energy and chemical energy, and achieve the purpose of energy storage.

The electric stack of the flow battery consists of several or dozens of single cells stacked and assembled in the form of a filter press. Each battery cell consists of two half-cells consisting of solid electrodes, bipolar plates, flow frames, and end plates. An ion-exchange membrane is sandwiched between the two half-cells to divide the single cell into positive and negative reaction areas, which allow proton exchange and prevent the migration of other reactive ions and impurity ions. The solid electrode provides a reaction site for the electrochemical reaction. The larger the electrode area, the higher the charge and discharge reaction rate, and the higher the corresponding power. The separator between two adjacent single cells is called a bipolar plate. The flow battery system consists of stacks, electrolyte, electrolyte storage tanks, circulation pumps, pipelines, auxiliary equipment, instruments, and detection and protection equipment. The electrolyte storage tanks are used to hold the positive and negative electrolytes respectively, and are equipped with two circulating pumps to deliver the electrolyte to each half-cell unit in a closed pipeline. When charging, the battery's state of charge (SoC) increases, and when discharging, the battery's state of charge (SoC) decreases.

During the charging and discharging process of the battery, the amount of reactive substances in the electrolyte gradually decreases, especially at the end of charge and discharge, the concentration of reactive substances is very low, and when the cut-off voltage range of charge and discharge is high, reactive activity is very likely to appear at the end of charge and discharge. Insufficient material supply will lead to deterioration of mass transfer, cause greater concentration polarization, and reduce battery efficiency. In order to ensure sufficient supply of reactants, the minimum value of electrolyte flow rate can be obtained through theoretical calculation:

In the formula: I is the charging and discharging current, A; F is Faraday's constant, about 96485C/mol; SoC is the state of charge of the battery, which can be calculated according to the concentration of active ions to be reacted and generated ions in the electrolyte.

The actual flow of electrolyte is:

Q＝fac× _Qmin

In the formula: fac is a dimensionless constant of the rate factor.

However, the flow rate of the electrolyte is not as fast as possible. When the upper limit of the flow rate is reached, increasing the flow rate cannot further reduce the concentration polarization loss of the battery or improve the efficiency of the battery. On the contrary, it will greatly increase the pump work and consume unnecessary electric energy. The life of the entire battery system also has a certain impact. Therefore, in practical applications, fac is generally taken as 4 to 20 to reconcile the contradiction between concentration polarization and pump work and maintain high battery efficiency.

However, the current flow optimization model only considers the contradiction between the concentration polarization and the pump work of the flow battery, ignoring the difference in the state of charge of the electrolyte between the stack and the storage tank. The applicant found through research that during the charging and discharging process of the flow battery, the state of charge (SoC) of the electrolyte between the stack and the storage tank will be different, especially at low flow rates. The difference will be very noticeable. For example, in the case of using 1.6mol/L electrolyte in the all-vanadium redox flow battery, if the flow rate coefficient fac=0.5, the maximum difference in state of charge between the storage tank and the stack will reach more than 0.8mol/L. When the high state of charge electrolyte flows out of the stack, it will mix with the low state of charge electrolyte in the storage tank, and the time difference in this process will cause the electrolyte state of charge in the storage tank to remain below The state of charge of the electrolyte in the stack. When the flow rate is very small, the difference will be very obvious. Since the charge and discharge cut-off voltage of the battery is judged according to the state of charge collected in the stack, this difference will seriously affect the utilization rate of the electrolyte. In other words, when the state of charge of the electrolyte in the stack is already higher than the charge cut-off voltage, the state of charge of the electrolyte in the storage tank is still very low, so most of the electrolyte is not used, even at In the case of high flow rate, this situation cannot be completely resolved. Therefore, it is particularly urgent to find ways to reduce or eliminate the electrolyte state of charge (SoC) difference between the stack and the tank. The method of the present invention can not only increase the utilization rate of the electrolyte under any rate condition, but also can increase the charging current density under the condition of low flow rate, so as to improve the response performance of the liquid flow battery.

The traditional flow battery adopts the operation mode of two storage tanks: first, add an equal volume of electrolyte solution into the positive and negative electrolyte storage tanks, and after the battery starts to operate, it first carries out the charging process, and the positive and negative electrolytes pass through the cycle respectively. The pump enters the stack area of the battery, and a redox reaction occurs on the electrode surface, which increases the state of charge (SoC) of the electrolyte, and then the electrolyte with the increased state of charge (SoC) flows out of the stack and returns to the positive state respectively. In the negative electrolyte storage tank, it is mixed with the low state of charge (SoC) electrolyte in the storage tank, so that the electrolyte is circulated until the voltage in the stack reaches the charge cut-off voltage. Then the discharge process is carried out, and the state of charge (SoC) of the electrolyte gradually decreases until the voltage in the stack reaches the discharge cut-off voltage, and a charge-discharge cycle is completed. In this mode of operation, if the flow rate is too low, the supply of reactive species in the stack will be insufficient, and the concentration polarization will increase, resulting in a decrease in battery efficiency. However, if the flow rate is too high, the pump work of the system will increase, and the battery system will also be reduced. s efficiency.

In order to balance the contradiction between concentration polarization and pump work, most of the current research is optimized by adjusting the flow rate. Relevant technical personnel have done in-depth research, and the following technologies have emerged:

The invention patent with the application number CN201010210100.9 discloses an all-vanadium flow energy storage battery system and its electrolyte flow cascade control strategy. Through experiments in different electrolyte temperature ranges, cell voltage ranges, and current density ranges, the comprehensive On the basis of considering the energy efficiency and power consumption of the all-vanadium redox flow energy storage battery system, determine the optimal electrolyte flow rate in different electrolyte temperature ranges, cell voltage ranges, and current density ranges, and control the frequency converter to adjust the work of the pump through a single-chip microcomputer The frequency and flow rate ensure that the all-vanadium redox flow energy storage battery system operates under the selected electrolyte flow rate.

The patent for invention with the application number CN201410746201.6 discloses an optimized control method for the electrolyte flow of an all-vanadium redox flow battery system. By proposing a control strategy for increasing the electrolyte flow in stages during the charging and discharging process of the battery, during the battery operation process In the process, according to the charge and discharge state value SOC collected by the charge and discharge state monitor, the required electrolyte flow rate is calculated, and the working frequency of the centrifugal pump is adjusted through the frequency converter to ensure that the all-vanadium redox flow battery system operates at the selected flow rate.

However, the above patents only focus on reconciling and balancing the contradiction between concentration polarization and pump work, and do not pay attention to the difference in the state of charge (SoC) of the electrolyte between the stack and the liquid storage tank. Even at relatively high flow rates, this difference is still not completely resolved. Moreover, this way of adjusting the flow rate is destined to prevent the flow battery system from operating at a lower flow rate, and there is a certain loss of pumping power. At present, only a very low current density can be used in the state of low flow rate to ensure that the supply of reactive species in the stack will not be too small.

There are also relevant technicians who have studied the operation mode of the pump. The following technologies emerged:

The invention application with the application number CN201410241236.4 discloses an automatic controller for the intermittent operation of the liquid flow pump of the lithium-ion flow battery. An automatic controller for the intermittent operation of the liquid flow pump is added to the lithium-ion flow battery system, which can automatically judge Lithium-ion flow battery usage, completely automatically start and stop the flow pump, and work intermittently, so that the positive and negative electrode suspensions of the lithium-ion flow battery are intermittently circulated, and are circulated after entering the positive and negative reaction chambers of the battery. go out. This method can reduce the working time of the liquid flow pump and reduce the pump work. However, this form cannot accurately control the volume of electrolyte entering the stack each time, and needs to judge the reaction time required for each electrolyte entering the stack, which has certain difficulties in the automatic operation of the system.

The invention application with the application number CN201610801986.1 discloses a current interrupter for a flow battery and a flow battery using the current interrupter. A current interrupter for a flow battery is added to the outlet pipe of the electric pump. The current interrupting part makes the liquid flow intermittently through rotation, so that the electrolyte is intermittently input into each cell stack section by section, and the electrolyte in the electrolyte pipeline is intermittently disconnected. The "current interrupter" described in this way also has the effect of "intermittent electrolyte circulation" in essence, but the structure is relatively complicated. The output power of the single battery is sacrificed.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the prior art, and to propose a flow battery pulse charging and discharging system and method for improving the utilization rate of the electrolyte. The state of charge (SoC) difference between the tanks greatly improves the utilization of the electrolyte.

The pulse charge and discharge system of the liquid flow battery described in the present invention improves the operation mode of the battery charge and discharge system. In addition to achieving the balance between the concentration polarization and the pump power, it can also reduce the energy consumption of the battery stack and the liquid storage tank. The difference in state of charge (SoC) between electrolytes improves the utilization of electrolyte, and can be applied to occasions with higher current density at low flow rates, which is not available in flow optimization and pump operation mode optimization The advantages.

The pulse charging and discharging system of the liquid flow battery described in the present invention is realized through the following technical solutions:

The flow battery pulse charging and discharging system that improves the utilization rate of the electrolyte has the following structure: the stack end plates on both sides of the flow battery have a positive electrolyte inlet, a negative electrolyte inlet, and a positive electrolyte outlet. The outlet port and the negative electrolyte outlet, the positive electrolyte inlet and the positive electrolyte outlet are all connected to the positive electrolyte storage tank through the infusion pipeline to form a circulation loop of the positive electrolyte; the negative electrolyte inlet and The negative electrolyte outlets are all connected to the negative electrolyte storage tank through the infusion pipeline to form a circulation loop of the negative electrolyte; the infusion pipelines are all provided with circulation pumps for providing electrolyte delivery power; the positive electrolyte storage Both the liquid tank and the negative electrolyte storage tank are equipped with stirring devices; the current collector plate of the flow battery is externally connected to the charging and discharging system. The charging and discharging system includes a battery charging and discharging detection device and a pulse timing power switch. The pulse timing power switch is connected in series. In the charge and discharge circuit of the battery charge and discharge detection device and the current collector, it is used to control the intermittent on and off of the charge and discharge circuit.

Preferably, the pulse timing power switch is connected with a computer for inputting pulse control signals.

Preferably, the stirring device is a magnetic rotor.

Preferably, the stack structure of the flow battery is as follows: a number of single battery structural units are sandwiched between the PP plates on both sides, and stack end plates are respectively fixed outside the PP plates on both sides.

Preferably, the flow battery is an all-vanadium flow battery, a zinc-bromine flow battery or a zinc-nickel flow battery.

Another object of the present invention is to provide a kind of method utilizing above-mentioned system to improve electrolyte utilization rate, and its steps are as follows:

First, add an equal volume of electrolyte to the positive electrolyte storage tank and the negative electrolyte storage tank, and turn on the stirring device in the two storage tanks to mix the electrolyte in the tank; turn on the circulation pump to make the positive and negative The electrolyte flows in the infusion pipeline, and enters the single cell structural unit in the stack through the end plate of the stack, the PP plate of the stack, the liquid inlet of the positive electrolyte, and the liquid inlet of the negative electrolyte respectively. Oxidation and reduction reactions occur to increase the state of charge of the electrolyte, and then return to the positive electrolyte storage tank and the negative electrolyte storage tank respectively through the positive electrolyte outlet and the negative electrolyte outlet to form a circulation loop ; Calculate the theoretical charging time and theoretical discharging time according to the volume of the positive and negative electrolytes, divide the charging and discharging time into several time periods and input them into the computer, control the on-off state of the pulse-type timing power switch, and make the battery charge and discharge detection device output With pulsed current, the electrolyte is intermittently charged in the stack; during the period when the charge and discharge detection device is not charging within the pulse cycle, the circulating pump that drives the positive and negative electrolyte circulation still keeps running; when the external charge and discharge system is connected When the battery voltage collected by the current collecting board has reached the charging cut-off voltage, the charging ends and the discharging process starts. At this time, the system still maintains the pulse discharge process until the current collecting board of the external charging and discharging system collects that the battery voltage has reached the discharge. When the cut-off voltage is reached, the discharge process ends and a complete charge-discharge cycle is completed.

Preferably, in each pulse cycle of charging or discharging, the total charging time is not lower than the theoretical charging time, and the total discharging time is not lower than the theoretical discharging time.

Preferably, the charging cut-off voltage is set to 1.7V.

Preferably, the discharge cut-off voltage is set to 0.8V.

The pulse charging and discharging system of the liquid flow battery described in the present invention controls the closing and opening of the pulse timing power switch through the computer, so that the battery charging and discharging detection device outputs a pulse current, that is: start-charging-stop- Charge-shutdown...discharge-shutdown-discharge-shutdown-end. During shutdown, the two circulation pumps 6 continue to run, reducing the difference in state of charge (SoC) of the electrolyte between the battery stack and the liquid storage tank, and reducing the concentration polarization between the battery stack and the liquid storage tank. After the shutdown process is over, the pulse timing power switch is closed, and the system continues the charging or discharging process. Finally, when the charge and discharge are cut off, the utilization rate of the electrolyte can be effectively improved, especially in the case of low flow rate, the utilization rate of the electrolyte can be significantly improved.

Compared with the prior art, the present invention has the following characteristics: first, the utilization rate of the positive and negative electrolytes is significantly increased, and the difference in the state of charge (SoC) of the electrolyte between the battery stack and the liquid storage tank can be greatly reduced , to reduce the concentration polarization between the stack and the liquid storage tank. Second, the battery can still be charged and discharged for a long time at a low flow rate, and can be applied to occasions with a higher current density at a low flow rate to keep the battery working normally. Third, in the case of a large volume of the liquid storage tank, it can ensure that the electrolyte in the liquid storage tank can maintain good uniformity, and avoid the impact of uneven mixing of the electrolyte on the battery.

Description of drawings

Fig. 1 is a basic schematic diagram of a flow battery pulse charging and discharging system for improving electrolyte utilization in a specific embodiment of the present invention.

Fig. 2 is a schematic diagram of the inlet and outlet of the anode electrolyte of the device shown in Fig. 1 in the present invention.

Fig. 3 is a schematic diagram of the inlet and outlet of the negative electrode electrolyte of the device shown in Fig. 1 in the present invention.

Fig. 4 is the relationship between the utilization ratio of the electrolyte and the flow rate β of the device of the present invention and the conventional device.

In the figure: stack end plate 1, stack PP board 2, single cell structural unit 3, infusion pipeline 4, positive electrolyte storage tank 5, circulation pump 6, negative electrolyte storage tank 7, magnetic rotor 8, Battery charge and discharge detection device 9, pulse timing power switch 10, computer 11, positive electrolyte outlet 12, positive electrolyte inlet 13, collector plate 14, bolt holes 15, negative electrolyte outlet 16, Negative electrolyte liquid inlet 17.

Detailed ways

The present invention will be further elaborated and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of the various implementations in the present invention can be combined accordingly on the premise that there is no conflict with each other.

As shown in Figures 1 to 3, in the embodiment, the flow battery pulse charging and discharging system to improve the utilization rate of the electrolyte is mainly composed of three parts, which are mainly divided into the stack part of the battery, the external circulation part of the electrolyte, and the battery The charging and discharging system (external power supply) part. Its main components include stack end plate 1, PP plate 2, single cell structural unit 3, infusion pipeline 4, positive electrolyte liquid storage tank 5, circulation pump 6, negative electrode electrolyte liquid storage tank 7, magnetic rotor 8, battery Charge and discharge detection device 9, pulse timing power switch 10, computer 11, positive electrolyte outlet 12, positive electrolyte inlet 13, collector plate 14, bolt holes 15, negative electrolyte outlet 16, negative electrode Electrolyte liquid inlet 17.

The stack part of the battery is mainly composed of stack end plate 1 (stainless steel end plate can be used), PP plate 2 (polyethylene material can be used to ensure uniform preload distribution of the battery) and several single cell structural units 3 structure, the stack end plate 1 is provided with bolt holes 15 in the circumferential direction for fastening and fixing. A plurality of single battery structural units 3 are clamped between the PP plates 2 on both sides, and cell stack end plates 1 are respectively fixed outside the PP plates 2 on both sides. The number of battery structural units 3 is not limited. Each single battery structural unit 3 can be divided into a current collector plate 14 (copper plate can be used to collect the charging state of the single battery from the bipolar plate and convert it into a voltage signal, and also deliver the current of the external power supply into the battery. control the charging or discharging of the battery), bipolar plates (graphite plates can be used to distinguish the positive and negative electrodes of the electrolyte and conduct electrical signals), liquid flow frames, sealing gaskets, electrodes (graphite felt can be used to provide The electrochemical reaction of the electrolyte provides an active area), ion exchange membrane (Nafion117 cation exchange membrane can be used to transfer hydrogen ions and water molecules at the positive and negative electrodes of the battery, and maintain the charge balance of the battery) and other main components.

The stack end plate 1 on both sides of the flow battery has a positive electrolyte inlet 13, a negative electrolyte inlet 17, a positive electrolyte outlet 12, and a negative electrolyte outlet 16, and the positive electrolyte inlet Both the port 13 and the positive electrolyte outlet 12 are connected to the positive electrolyte storage tank 5 through the infusion pipeline to form a circulation loop of the positive electrolyte; the negative electrolyte inlet 17 and the negative electrolyte outlet 16 are all connected through the infusion line The pipeline is connected to the negative electrode electrolyte liquid storage tank 7 to form a circulation loop of the negative electrode electrolyte. Both the infusion pipelines of the positive and negative electrodes are provided with circulation pumps 6 for providing electrolyte delivery power, preferably using peristaltic circulation pumps to achieve adjustable flow rates. Both the positive electrolyte liquid storage tank 5 and the negative electrode electrolyte liquid storage tank 7 are provided with magnetic rotors 8 for stirring the electrolyte. The current collecting plate 14 of the liquid flow battery is externally connected to the charging and discharging system. The charging and discharging system includes a battery charging and discharging detection device 9 and a pulse type timing power switch 10. At the same time, the output current can detect status information such as the voltage at the collector plate 14 and the battery capacity in real time. The on-off of the circuit is controlled by the pulse timing power switch 10 according to the pulse signal stored internally or received from the outside. In this embodiment, the pulse timing power switch 10 is realized by a programmable timing switch. The pulse-type timing power switch 10 is connected in series in the charge-discharge circuit of the battery charging and discharging detection device and the current collector 14, and the overall breaking of the breaking control circuit of the pulse-type timing power switch 10 itself can finally be realized according to intermittent breaking. The pulse control signal controls the intermittent on-off of the charging and discharging circuit. As shown in Fig. 4, compared with the electrolyte utilization rate of the conventional device, the electrolyte utilization rate of the device of the present invention is greatly improved at a low flow rate β.

Based on this device, the method for improving the utilization rate of the electrolyte is to input an intermittent off-off pulse signal to the pulse timing power switch 10, so that the charging and discharging system no longer continuously charges the electrolyte in the flow battery, Instead, it has been transformed into intermittent charging. During the non-charging period, the circulating pump 6 still runs continuously to ensure that the electrolyte in the battery stack and the liquid storage tank is fully mixed to reduce the difference in the state of charge (SoC) of the electrolyte between the battery stack and the liquid storage tank , until the charging cut-off voltage is reached, the charging process is completed and the discharging process is entered. During the discharge process, the pulse timing power switch 10 is also intermittently turned off to keep the electrolyte solution intermittently discharged until the discharge cut-off voltage is reached, and the discharge process is completed. This constitutes a charge-discharge cycle.

The specific method for improving the utilization rate of the electrolyte is described in detail below, and the steps are as follows:

First, add an equal volume of electrolyte to the positive electrolyte storage tank 5 and the negative electrolyte storage tank 7, and add a magnetic rotor 8 to each of the two storage tanks to ensure the uniformity of electrolyte mixing during system operation . Turn on the circulating pump 6 to make the positive and negative electrolytes flow in the infusion pipeline 4, and enter through the stack end plate 1, the stack PP board 2, the positive electrolyte inlet 13, and the negative electrolyte inlet 17 respectively. In the single-cell structural unit 3 in the electric stack, a redox reaction occurs in the single-cell. After the reaction is completed, the state of charge (SoC) of the electrolyte increases, and then passes through the positive electrolyte outlet 12 and the negative electrolyte outlet respectively. The port 16 returns to the positive electrode electrolyte liquid storage tank 5 and the negative electrode electrolyte liquid storage tank 7. Calculate the theoretical charging and discharging time according to the volume of the positive and negative electrolytes, divide the theoretical charging and discharging time into several time periods and input it into the computer 11 (preferably divided into 5-20 sections), and control the state of the pulse timing power switch 10 , so that the battery charge and discharge detection device outputs a pulsed current, that is: start-charge-stop-charge-stop...discharge-stop-discharge-stop-end, the stop time is not limited (so that the electrolyte can be fully Mixing shall prevail, preferably 1 min). When the pulse timing power switch 10 is connected, the battery charge and discharge detection device 9 starts to output current to the collector 14, so that the system is charged in a predetermined pulse charge and discharge mode. During the shutdown process, the two circulation pumps 6 continue to operate, reducing the difference in the state of charge (SoC) of the electrolyte between the battery stack and the liquid storage tank, and reducing the concentration polarization between the battery stack and the liquid storage tank. Then the pulse-type timing power switch 10 is closed and communicated again, and the system continues the charging process. The above-mentioned pulse process reciprocates n times. When the current collector plate 14 of the external charging and discharging system collects the voltage of the battery and has reached the charging cut-off voltage (preferably, the charging cut-off voltage is set to 1.7V), the charging ends and the discharge process begins. At this time, the system still maintains a pulsed discharge process until the current collecting plate 14 of the external charging and discharging system collects the voltage of the battery and has reached the discharge cut-off voltage (as preferably, the discharge cut-off voltage is set to 0.8V), the discharge process ends, and the discharge process is completed. A complete charge and discharge cycle.

The above-mentioned embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. Various changes and modifications can be made by those skilled in the relevant technical fields without departing from the spirit and scope of the present invention. For example, the specific structure of the flow battery can adopt various methods in the prior art, and is not limited to the structure described in the embodiment. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (9)

1. A flow battery pulse charging and discharging system that improves the utilization rate of the electrolyte, characterized in that the stack end plates (1) on both sides of the flow battery have a positive electrolyte inlet (13), a negative electrolyte The liquid inlet (17), the positive electrolyte outlet (12) and the negative electrolyte outlet (16), the positive electrolyte inlet (13) and the positive electrolyte outlet (12) are all passed through the transfusion The pipeline is connected to the positive electrolyte storage tank (5) to form a circulation loop of the positive electrolyte; the negative electrolyte inlet (17) and the negative electrolyte outlet (16) are both connected to the negative electrolyte storage tank through the infusion pipeline. The liquid tank (7) constitutes the circulation circuit of the negative electrode electrolyte; the circulation pump (6) for providing the electrolyte delivery power is arranged on the described infusion pipeline; the positive electrode electrolyte liquid storage tank (5) and the negative electrode electrolyte storage tank Stirring devices are installed in the liquid tanks (7); the current collecting plate (14) of the flow battery is externally connected to a charging and discharging system, and the charging and discharging system includes a battery charging and discharging detection device (9) and a pulse-type timing power switch (10). A timing power switch (10) is connected in series in the charging and discharging circuit of the battery charging and discharging detection device and the current collecting plate (14), and is used to control the intermittent on-off of the charging and discharging circuit. 2. The flow battery pulse charging and discharging system for improving electrolyte utilization as claimed in claim 1, wherein the pulse timing power switch (10) is connected with a computer (11) for inputting pulse control signals ). 3. The flow battery pulse charging and discharging system for improving electrolyte utilization according to claim 1, characterized in that the stirring device is a magnetic rotor (8). 4. The flow battery pulse charge and discharge system for improving electrolyte utilization as claimed in claim 1, characterized in that, the stack structure of the flow battery is as follows: several PP plates (2) on both sides are clamped The single cell structure unit (3) is respectively fixed with stack end plates (1) outside the PP plates on both sides. 5. The flow battery pulse charge and discharge system for improving electrolyte utilization as claimed in claim 1, wherein the flow battery is an all-vanadium flow battery, a zinc-bromine flow battery or a zinc-nickel solution flow battery. 6. A method for utilizing the system as claimed in claim 2 to improve the utilization rate of electrolyte, is characterized in that, the steps are as follows: at first, add etc. volume of electrolyte, and respectively turn on the stirring device in the two liquid storage tanks to mix the electrolyte in the tank; turn on the circulating pump (6) to make the positive and negative electrolyte flow in the infusion pipeline (4), respectively Through the stack end plate (1), the stack PP plate (2), the positive electrolyte inlet (13), the negative electrolyte inlet (17) into the single cell structural unit (3) in the stack, Oxidation-reduction reactions occur in the single cell to increase the state of charge of the electrolyte, and then return to the positive electrolyte storage tank (5) through the positive electrolyte outlet (12) and the negative electrolyte outlet (16) respectively. ) and the negative electrode electrolyte liquid storage tank (7), forming a circulation loop; according to the theoretical charging time and theoretical discharging time calculated according to the volume of the positive and negative electrode electrolytes, the charging and discharging time is divided into several time periods and input into the computer (11) , control the on-off state of the pulse-type timing power switch (10), so that the battery charge-discharge detection device outputs a pulse-type current, and the electrolyte is intermittently charged in the stack; the charge-discharge detection device does not charge within the pulse cycle During the period, the circulation pump (6) driving the positive and negative electrolyte circulation still keeps running; when the current collecting plate (14) of the external charging and discharging system collects that the voltage of the battery has reached the charging cut-off voltage, the charging ends and the discharging process starts. At this time, the system still maintains the pulse discharge process until the current collecting plate (14) of the external charging and discharging system collects the voltage of the battery and has reached the discharge cut-off voltage, the discharge process ends and a complete charge and discharge cycle is completed. 7. The method according to claim 6, characterized in that, in each pulse cycle of charging or discharging, the total charging time is not lower than the theoretical charging time, and the total discharging time is not lower than the theoretical discharging time . 8. The method according to claim 6, wherein the charging cut-off voltage is set to 1.7V. 9. The method according to claim 6, characterized in that the discharge cut-off voltage is set to 0.8V.

Images