JPH0447904Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a liquid circulation type metal-halogen battery.
In particular, the present invention relates to a liquid circulation type halogen battery in which the flow rate and flow velocity distribution of the electrolytic solution flowing in the reaction tank are made uniform.

[Prior art] Metal-halogen batteries have traditionally used zinc-halogen batteries.
Bromine secondary batteries and zinc-chlorine secondary batteries are known. Such secondary batteries obtain practical voltage and current by connecting single cells in series or parallel as necessary. It is also often used as a bipolar stack battery.

The principle of the metal-halogen battery will be explained with reference to FIG.

In the figure, a positive electrode 12 and a negative electrode 14 are separated by a separator 16 into a positive electrode chamber 10a and a negative electrode chamber 10b in a reaction tank 10, and piping is connected between the reaction tank 10, a positive electrode liquid storage tank 18, and a negative electrode liquid storage tank 20. An electrolyte circulation path is formed through 22. At this time, the electrolytic solution flowing through the pipe 22 is
a, 24b to the reaction tank 10.

In the reaction tank, during charging, halogen is generated on the positive electrode side, and metal is deposited on the negative electrode side.

Further, during discharge, the metal deposited on the negative electrode plate is oxidized and becomes metal ions and dissolved in the electrolyte, and the halogen in the electrolyte is reduced and becomes halogen ions and dissolved in the electrolyte.

FIG. 4 is an exploded inclined view of a conventional electrolyte circulation type stacked secondary battery based on the above-mentioned principle.

In the same figure, the electrode plate 26 is composed of an insulating part 28 and a conductive part 30, and a manifold 32 is provided on the diagonal line thereof. Further, the separator 34 has a separator frame 36 around the separator film 34a, and a manifold 38 and a channel 40 are formed in the separator frame 36 for supplying electrolyte to the positive electrode chamber and the negative electrode chamber.

In metal-halogen batteries, the electrolyte circulates from the electrolyte tank through each liquid chamber in the battery stack and back to the electrolyte tank. Since the liquid flows through the chambers, if the flow within each chamber is not uniform, overvoltage may occur or uneven electrodeposition may occur, resulting in unfavorable conditions for the battery.

Furthermore, in order to prevent shunt current, the electrolyte inlets and outlets have conventionally been arranged diagonally at the upper and lower corners of the battery as shown in FIG. 4. In addition, the area of the conductive part 30 of the electrode is 600 to 1200
When the diameter was as large as cm, it was difficult to flow the electrolyte uniformly.

As a means to solve this problem, JP-A-57-115772
As disclosed in the publication, there was one in which a rectifying plate group 42 was formed between the channel 40 and the separator film 34a shown in FIG. As a result, it was possible to obtain a uniform flow velocity distribution and a uniform flow rate distribution of the electrolytic solution in each of the positive electrode chamber and negative electrode chamber.

[Problems to be solved by the invention] Conventional problems However, the structure of the conventional rectifying plate group is as follows.
Due to the difficulty of rectifying the flow to obtain a uniform flow velocity distribution, it was constructed with multiple rows of rectifying plates.

That is, in the conventional structure described above, the gap provided between each rectifying plate 42 is constant;
Therefore, in order to obtain a uniform flow velocity and flow rate distribution, it is necessary to change the length of the rectifying plate 42 itself. was variable.

In the structural arrangement of such current plates, there is actually a limit to the size of a short current plate due to the mechanical strength required for each current plate 42.
As a result, if the length of the baffle plate 42 on the side farthest from the inlet and outlet is set to the minimum value, the length of the baffle plate immediately adjacent to the inlet and outlet will be considerably large in order to obtain a practically uniform distribution. A large length had to be provided, and as a result, there was a fear that eddies of the electrolyte flow would be generated on the downstream side of the current plate.

Therefore, in the conventional device described above, in order to quickly eliminate the vortices caused by such turbulent flow, a second straightening plate is further installed downstream of the baffle plate for obtaining the uniform distribution.
It was necessary to provide rectifying plates for the first row and the third row.

When the rectifying plate group is composed of multiple rows of rectifying plates in this way, the vertical width of the rectifying plate becomes large, which is useful for on-vehicle batteries such as electric vehicle forklifts where a low height is preferred for mounting batteries. It had become unsuitable for this purpose.

Further, when the current plate group is constituted by multiple rows of current plates, gas tends to accumulate between the multiple rows, and this gas becomes a cause of obstructing the flow of the electrolytic solution.

Purpose of the invention This invention was made in order to solve such problems.It makes the flow rate and flow velocity distribution of the electrolyte flowing in the reaction tank uniform, thereby eliminating the unevenness of the electrolyte. The object of the present invention is to provide a liquid circulation type metal-halogen battery that prevents occurrence of overvoltage, poor metal deposition, etc. caused by flow.

[Means and effects for solving the problems] The liquid circulation type metal-halogen battery according to this invention has a structure in which an electrolyte inlet, an electrolyte outlet, and a reaction tank are separated from each other and are arranged in a row. A first rectifier plate group and a second rectifier plate group are provided which are arranged at a substantially constant pitch. By arranging the rectifier plate groups in a line in this manner, the structure of the rectifier is simplified and the area occupied by the rectifier can be minimized.

In this case, the electrolyte is circulated between the electrolyte storage tank and the reaction tank, and as such electrolyte flows into and out of the reaction tank, these first and second rectifiers The width of the gap in the plate group through which the electrolytic solution passes is made smaller near the inlet, and becomes larger as it moves away from the inlet.

Therefore, the pressure after the electrolytic solution passes through the gap becomes equal at all locations in the reaction tank, and the flow of the electrolytic solution is made uniform. Therefore, metal is uniformly electrodeposited on the negative electrode side, and overvoltage can be prevented from occurring.

Furthermore, according to the present invention, as mentioned above, the arrangement pitch of the rectifier plates is kept approximately constant, while the gap length is made variable, so the length of each rectifier plate can be reduced, and as a result, the electrolyte flow is It has the advantage that there are few vortices generated on the downstream side, and a sufficient flow straightening effect can be obtained even with a single row of straightening plates.

Moreover, the gap width is formed to vary according to a predetermined function, and can be easily manufactured regardless of the size of the structure without requiring a prototype for determining the gap size.

[Embodiments] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 is an explanatory view of the main parts of a liquid circulation type metal-halogen battery according to the present invention.

In the figure, the separator 6 includes a separator film 50 and a separator frame 60 that is provided around the outer periphery of the separator film 50 and holds the separator film 50.

At the upper and lower portions of the separator 62 in FIG. Manifolds 44, 54 are provided.

The electrolyte then flows from an electrolyte storage tank (not shown) into a reaction tank 52 formed between the separator membrane 50 and an electrode plate (not shown), where a predetermined electrochemical reaction is performed. , and moves while being pumped in a circulation path that returns to the electrolyte storage tank again.

That is, the electrolytic solution is transferred from the electrolytic solution storage tank to the inflow side manifold 44 to the outflow side channel 46 to the inflow side straightening plate group 48 to the reaction tank 52 to the outflow side straightening plate group 58.
→Discharge side channel 56→Discharge side manifold 5
4 → It will circulate through the electrolyte storage tank route.

Here, the characteristic feature of the present invention is that the baffle plate groups 48 and 58 are arranged in a line between the electrolyte inlet and outlet and the reaction tank, partitioning them from each other, and This current plate group 4
Each rectifier plate 48-1, 48-2 in 8, 58
..., 58-1, 58-2... are formed so that the gap width increases in proportion to a predetermined function formula as the distance from the electrolyte inlet side or the electrolyte outlet side increases.

In this embodiment, the current plate group 48, 58
are a plurality of rectifying plates 48-1, 48-2, respectively.
and 58-1, 58-2..., and as shown in FIG.
The heights of 8-2... and 58-1, 58-2 are made equal to the height of the separator frame 60. This is so that when the electrode plates are sequentially stacked on the front and back sides of the separator frame 60, the separator frame 60 and the electrode plates are brought into close contact with each other to prevent the electrolyte from leaking from the stacked portion.

Moreover, each rectifying plate 48-1, 48- in the above
2..., 58-1, 58-2... adjacent pitches P
is constant, the gap width d between the current plates is set to increase as x increases according to the formula d=1/(x-) ² +A ² (1).

Note that d is the gap width between the rectifier plates, width of the rectifier plate group from the electrolyte inlet, x is the distance from the electrolyte inlet, and A is a correction coefficient, which can take a value of 0 to 0.

FIG. 8 shows the value of d based on the above formula (1). Here, P = 15 mm, = 350 mm, and A = 100.

Next, the calculation results for obtaining the above equation (1) will be explained below.

First, a model of a liquid circulation type battery as shown in FIG. 6a is set up.

In the figure, in order for the flow rate of the electrolytic solution to be uniform, the pressure distribution must be linear over the entire area as shown in Figure 6b.

Therefore, when the gap a is constant, a model calculation is performed to determine at what density the gap should be distributed in the x direction so that the flow rate passing through the gap is constant in the x direction and the pressure distribution is linear.

First, by considering the balance between the change in flow rate through the flow path and the flow rate flowing out through the gap, we can calculate that ak(x)u(x)+〓V(x)/〓xW=0 − Also, the flow rate flowing out through the gap is calculated as follows. Since the flow rate must be constant, k(x)・u(x)=Cc=const − The pressure generated by the liquid passing through the gap is P(x)=λu(x) − Next, The pressure generated when the liquid passes through the channel is given by the following equation.

dP(x)/dx=-12μ/h ² V(x) − Here, λ: Proportionality coefficient μ: Viscosity coefficient h: Channel thickness P: Pressure W: Channel width P ₀ : At inlet Pressure P(x): Pressure at a distance x from the inlet V ₀ : Inflow flow rate V(x): Flow rate at a distance x from the inlet V(): Flow rate at the end of the flow path u(x): Gap Flow rate passing through and exiting a: Gap size (constant) k(x): Gap density Substitute the above equation into aCc+W∂/∂x(-h ² dP(x)/12μdx)=0 aCc-h ² λW /12μ・d ² u(x)/dx ² = 0 From this, d ² u(x)/dx ² = 12μaCc/λWh ² ≡C ₁ u(x)=C ₁ /2x ² +C ₂ x+C ₃ k(x ) = (C ₁ / 2x ² + C ₂ x + C ₃ ) ^-1 × Cc P (x) = λ (C ₁ / 2x ² + C ₂ x + C ₃ ) V (x) = -h ₂ λ / 12μ (C ₁ x + C ₂ ) From V() = O, V(O) = V ₀ , C ₂ = -12μ/h ² λV ₀ , C ₁ = 12μ/h ² λV ₀ From this, C ₂ = -C ₁ ∴V(x) = V ₀ (1-x/) P(x)=λ( _C1 / ^2x2 +C2x+ _C3 )=λ( _C1 / _2x2 - ^C1x + _C3 ) _∴P0 = _λC3 , _P ()=λ ( _-C1 / ²² + _C3 ) u(x)= _C1 /2x2 ^- C1x+ _C3 = _C1 / ₂ (x-) ^2- _C1 / ²² + _C3 k(x)=Cc× (C ₁ /2x ² −C ₁ x+C ₃ ) ^-1 = Cc×{C/2(x-) ² −C ₁ /2 ² +C ₃ } ¹ = Cc・C ₁ /2 {(x-) ² − ² +2C ₃ /C ₁ } ^-1Here , if - ² +2C ₃ /C ₁ = A ² , then k(x) = Cc・C ₁ c/2 1/(x-) ² +A ² ∴k(x )∝1/(x-) ² +A ² From this, the width of the gap can be determined to be proportional to 1/(x-) ² +A ² . If the back is flowing too much
Adjust the size of A ² .

As described above, in this example, the flow rate of the electrolyte is
It has been found that a uniform flow can be obtained in the reaction tank 52 at 100 ml/mm or more, and the following effects can be achieved.

A uniform flow velocity distribution can be obtained within the reaction tank 52 over a wide range of flow rates.

By making the flow in the reaction tank 52 uniform, the electrodeposition of the metal deposited on the negative electrode becomes uniform.

By arranging the rectifying plate groups 48 and 58 in a row, the structure is simplified and the area of the rectifying section can be reduced. Therefore, the overall size of the battery can also be reduced.

In the case of conventional baffle plate groups with multiple rows, it was necessary to conduct trial manufacturing experiments many times to determine the gap size, but in this example, it can be easily determined based on the above formula. .

In the structure of multiple rows of rectifier plates, gas tends to accumulate between the rows of rectifier plates, and this gas obstructs the flow of the electrolyte, but in the case of a single row of rectifier plates, gas No stagnation,
Therefore, the electrolyte flows smoothly.

Since the gap between the rectifier plates at the electrolyte inlet and outlet is small, the shaft current can be reduced.

[Effect of the device] As explained above, this device provides a group of rectifying plates arranged in a line between the electrolyte inlet and the reaction tank, and sets the gap width of each of the rectifying plates to follow a predetermined function formula. By setting this, it is possible to make the flow velocity distribution of the electrolytic solution uniform in the reaction tank, and to prevent occurrence of overvoltage and poor electrodeposition of metal caused by non-uniform flow of the electrolytic solution.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main parts of a liquid circulation type metal-halogen battery according to the present invention, and FIG. 2 is a sectional view taken along line A-A.
Figure 3 is an explanatory diagram of the principle of a liquid circulation type battery, Figures 4 and 5 are exploded perspective views of a conventional stacked liquid circulation type metal-halogen battery, and Figure 6a is a schematic illustration of a liquid circulation type battery. Figure 6b is a diagram showing the pressure distribution, Figure 6c is an explanatory diagram of symbols, Figure 7 is a diagram showing the relationship between distance from the outflow and gap density, and Figure 8 is an explanation of the contents of d. It is a diagram. 44,54...manifold, 46,56...
Channel, 48, 58... Rectifier plate group, 50...
Separator membrane, 52... Reaction tank, 60... Separator frame, 62... Separator.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a liquid circulation metal-halogen battery in which an electrolyte is circulated between a reaction tank and an electrolyte storage tank,
A first baffle plate group and a second baffle plate group are provided between the electrolytic solution inlet and outlet and the reaction tank, partitioned from each other and arranged in a line at a substantially constant pitch. A liquid circulating type metal device characterized in that the gap width of each current plate in the second current plate group is formed so as to gradually increase as the distance from the electrolyte inlet side or the electrolyte solution outlet side increases.
halogen battery. (2) The battery according to claim 1 of the utility model registration, characterized in that the gap width of each rectifying plate increases according to the following functional formula:
halogen battery. d=1/(-x) ² +A ² d is the gap width between the current plates, is the width of the current plate group from the electrolyte inlet, x is the distance from the electrolyte inlet, and A is the correction coefficient.