A reduction furnace base

Abstract

The utility model relates to a reduction furnace base belongs to polysilicon production equipment technical field, including the chassis, multiple electrode assemblies, electrode assembly includes electrified electrode, support electrode, upper connecting rod, lower connecting rod, electrified electrode has two, the support electrode number is 2n, two adjacent support electrode combinations support electrode pair, the support electrode pair number is n, wherein n is the integer of 0 to 3, the one end of electrified electrode and support electrode is all fixedly connected with the chassis, and the one end of electrified electrode and its adjacent support electrode is away from the chassis and is fixedly connected through the upper connecting rod, and the lower end of two support electrodes in the support electrode pair is fixedly connected through the lower connecting rod, and the upper end of adjacent support electrode of adjacent support electrode pair is fixedly connected through the upper connecting rod, and electrified electrode and support electrode form series connection circuit through the upper connecting rod, lower connecting rod. The utility model realizes that electrode seat number reduces 60%, reduced the chassis welding deformation and copper, graphite to the polysilicon pollution, fundamentally changed reduction furnace starting mode.

Description

Technical Field

[0001] This utility model relates to the technical field of polysilicon production equipment, specifically to a reduction furnace base. Background Technology

[0002] In the existing technology, the electrode structure of the reduction furnace is that a silicon core is installed on the top of each electrode, and two electrodes and two silicon cores are connected at the top to form a pair of rods. Then, each pair of electrodes is connected in series through an external electrode connection plate to form a series circuit.

[0003] The electrodes are installed inside the reduction furnace chassis, which places strict requirements on sealing and cooling, resulting in a relatively complex structure. Cooling water is circulated through each electrode, which carries away heat from the furnace. At the same time, the circulation of the cooling water requires high-power equipment, which consumes a large amount of electrical energy.

[0004] The silicon core is held in place by a graphite base and a graphite chuck at the top of the electrode. During the polycrystalline silicon production process, carbon in the graphite diffuses into the interior of the polycrystalline silicon, resulting in insufficient purity of electronic-grade polycrystalline silicon, which becomes solar-grade polycrystalline silicon (solar-grade polycrystalline silicon is 0.5 meters away from the graphite component). During the deposition of polycrystalline silicon, the presence of the graphite component directly affects the purity of electronic-grade polycrystalline silicon.

[0005] During the production process, copper electrodes can contaminate electronic-grade polysilicon, and excessive copper can reduce the purity of polysilicon.

[0006] In other words, the number of electrodes used has a direct impact on polysilicon yield, quality, and energy consumption.

[0007] In addition, the existing electrode arrangement means that the reduction furnace is started in pairs. Due to insulation limitations, the voltage level cannot be increased continuously, which means that electrodes on the same layer cannot be started at the same time, resulting in slow furnace temperature rise and long start-up time. Utility Model Content

[0008] The purpose of this invention is to provide a reduction furnace base that can reduce the number of electrodes on the reduction furnace chassis, thereby increasing polysilicon yield and quality and reducing start-up time.

[0009] To achieve the above objectives, this utility model provides a reduction furnace base, comprising: The chassis and multiple sets of electrode assemblies; the electrode assembly includes an energized electrode, a supporting electrode, an upper connecting rod, and a lower connecting rod. There are two energized electrodes and 2n supporting electrodes. Two adjacent supporting electrodes are combined to form a supporting electrode pair. The number of supporting electrode pairs is n, where n is an integer from 0 to 3. One end of both the energized electrode and the support electrode is fixedly connected to the chassis. The energized electrode and the end of its adjacent support electrode away from the chassis are fixedly connected by an upper connecting rod. The lower ends of the two inner support electrodes are fixedly connected by a lower connecting rod. The upper ends of adjacent support electrodes are fixedly connected by an upper connecting rod. The energized electrode and the support electrode form a series circuit through the upper and lower connecting rods.

[0010] As a preferred technical solution of this utility model, the energized electrode includes a main stage insulation part that penetrates the chassis, an electrode seat is provided on the chassis, the electrode seat penetrates the chassis, and the main stage insulation part is inserted into the electrode seat; the part of the energized electrode located above the chassis is provided with an energized electrode clamping part, the energized electrode clamping part clamps the silicon core, and the energized electrode clamping part is provided on the main stage insulation part.

[0011] As a preferred technical solution of this utility model, the chassis is provided with mounting holes that do not penetrate the bottom of the chassis. A secondary insulating part is installed inside the mounting holes, and a supporting electrode clamping part is installed inside the secondary insulating part. The supporting electrode clamping part clamps the solid silicon core.

[0012] As a preferred technical solution of this utility model, the chassis is provided with a mounting hole that penetrates through the bottom of the chassis. A secondary insulating part is installed in the mounting hole, and a supporting electrode clamping part is installed in the secondary insulating part. The supporting electrode clamping part clamps the hollow silicon core.

[0013] As a preferred technical solution of this utility model, adjacent silicon cores are fixedly connected in sequence by an upper connecting rod and a lower connecting rod.

[0014] As a preferred embodiment of this utility model, the material of the single support electrode clamping part is any one of alumina, quartz, silicon nitride, and silicon carbide.

[0015] As a preferred embodiment of this utility model, the material of the single energized electrode clamping part is either copper or graphite.

[0016] As a preferred embodiment of this invention, at least two sets of electrode assemblies have different numbers of supporting electrode pairs.

[0017] As a preferred technical solution of this utility model, the electrode assembly is arranged in multiple radial layers on the chassis, with a first distribution layer, a second distribution layer, and a third distribution layer arranged sequentially outward from the center of the chassis; each group of electrode assemblies in the first distribution layer does not include a pair of supporting electrodes; each group of electrode assemblies in the second distribution layer includes a pair of supporting electrodes; and each group of electrode assemblies in the third distribution layer includes two pairs of supporting electrodes.

[0018] As a preferred embodiment of this utility model, the electrode assembly is arranged radially in multiple layers on the chassis, with a first distribution layer, a second distribution layer, a third distribution layer, and an outer distribution layer arranged sequentially outward from the center of the chassis; each group of electrode assemblies in the first distribution layer does not include a pair of supporting electrodes; each group of electrode assemblies in the second distribution layer includes a pair of supporting electrodes; each group of electrode assemblies in the third distribution layer includes three pairs of supporting electrodes; and each group of electrode assemblies in the outer distribution layer includes three pairs of supporting electrodes.

[0019] The advantages of this utility model are: 1. By using multiple sets of electrode assemblies arranged radially in multiple layers on the reduction furnace chassis, the start-up method of the reduction furnace can be fundamentally changed. The first distribution silicon core is started first, with each pair of rods starting under high voltage individually; at this time, the furnace temperature rises rapidly, and the second distribution layer starts; when the furnace reaches the preset temperature, the third distribution layer silicon core is started; when the furnace reaches the preset temperature, the outer distribution ring silicon core is started. The reduction furnace starts up gradually, resulting in a stable start-up process, reduced vibration, and high power supply stability and safety. This achieves step-by-step electrode breakdown in the reduction furnace, enhancing stability and safety.

[0020] 2. The number of electrode holders used is reduced by 60%, chassis welding deformation is reduced, and contamination of polysilicon caused by copper and graphite electrodes is reduced.

[0021] 3. When the supporting electrode clamps the hollow silicon core, the hollow silicon core can serve as a channel for the reaction gas to enter and exit, reducing the need for openings on the chassis. Attached Figure Description

[0022] Appendix Figure 1 This is a schematic diagram of the overall structure of the 24-pair rod reduction furnace chassis shown in Embodiment 1 of this utility model; Appendix Figure 2 This is a schematic diagram of the structure of a set of electrode components in Embodiment 1 of this utility model; Appendix Figure 3 A schematic diagram of the power connection structure for the electrode assembly; Appendix Figure 4 for Figure 1 A magnified view of the area at point W; Appendix Figure 5 This is a schematic diagram of the chassis structure of a reduction furnace using existing technology. Appendix Figure 6 This is a schematic diagram of the chassis structure of the 48-pair rod reduction furnace shown in Embodiment 2 of this utility model; Appendix Figure 7 This is a schematic diagram of the overall structure of the 48-pair rod reduction furnace chassis shown in Embodiment 2 of this utility model.

[0023] Appendix Figure 8 for Figure 7 A magnified view of part A.

[0024] In the picture: 1. Chassis; 2. Power connection components; 3. Energized electrode; 31. Energized electrode clamping part; 4. Support electrode; 41. Support electrode clamping part; 5. Upper connecting rod; 6. Lower connecting rod; 7. Main insulation part; 8. Secondary insulation part; 9. Silicon core; 10. Electrode holder; 11. Support seat. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0027] The directional terms mentioned in the embodiments of this utility model, such as "upper" and "lower", are only for reference to the direction of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this utility model, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model. Moreover, relational terms such as "primary" and "secondary" are only used to distinguish one component from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components.

[0028] In the description of embodiments of this utility model, the term "comprising" or any other variations thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0029] like Figure 1 , 2 As shown, Embodiment 1 of this disclosure provides a reduction furnace base, which includes a chassis 1 and multiple sets of electrode assemblies; the electrode assembly includes an energized electrode 3, a supporting electrode 4, an upper connecting rod 5, and a lower connecting rod 6; Both the energized electrode 3 and the supporting electrode 4 are fixedly connected to the chassis 1 at one end and are fixed to the chassis 1 by screwing.

[0030] like Figure 2 As shown, when there are two energized electrodes 3 and two supporting electrodes 4, two adjacent supporting electrodes 4 are combined to form a supporting electrode pair, and the number of supporting electrode pairs is one. The energized electrode 3 and the end of its adjacent supporting electrode 4 away from the chassis 1 are fixedly connected by an upper connecting rod 5, and the lower ends of the two supporting electrodes 4 within the supporting electrode pair are fixedly connected by a lower connecting rod 6. When there are two supporting electrode pairs, the energized electrode 3 of an adjacent supporting electrode pair and the upper end of the adjacent supporting electrode 4 are fixedly connected by an upper connecting rod 5 to form a series connection (not shown in the figure).

[0031] In this design, chassis 1 refers to the base structure that supports the electrode assembly, which can be implemented using a ring-shaped metal plate for mounting and fixing the electrodes. The energized electrode 3 refers to the conductive component that carries current and establishes an electrical connection with an external power source. The supporting electrode 4 refers to the auxiliary electrode that serves both structural support and current transmission functions. The upper connecting rod 5 refers to the connecting member located at the top of the electrode, used to establish a series path between adjacent electrodes. The lower connecting rod 6 refers to the connecting member located at the bottom of the electrode, used to form a current loop between the supporting electrodes 4.

[0032] The energized electrode 3 and the supporting electrode 4 form a series circuit through the upper connecting rod 5 and the lower connecting rod 6. The series circuit is: energized electrode 3 - upper connecting rod 5 - supporting electrode 4 - lower connecting rod 6 - supporting electrode 4 - upper connecting rod 5 - energized electrode 3. The two ends of the energized electrode 3 are connected to the power supply.

[0033] The energized electrode 3 includes a main-stage insulating portion 7 that penetrates the chassis 1. An electrode holder 10 is provided on the chassis 1, penetrating the chassis 1. The main-stage insulating portion 7 is inserted into the electrode holder 10. A conductive element is disposed inside the main-stage insulating portion 7, and the conductive element is connected via... Figure 3 The power connection assembly 2 shown is connected to a power source, which is connected to the terminal block 10 to form a complete circuit. The primary insulation part 7 is fixedly connected to the chassis 1, and the secondary insulation part 8 is also fixedly connected to the chassis 1. The chassis 1 is provided with a support base 11, which is mounted on the chassis 1. The secondary insulation part 8 is mounted on the support base 11, which is located within the mounting holes of the chassis and fixed by bolts or welding. The primary insulation part 7 prevents arcing discharge from the upper and lower ends of the energized electrode 3 to the chassis 1. The secondary insulation part 8, being only located above the chassis 1, prevents arcing discharge from the upper end of the supporting electrode 4 to the chassis 1. The primary insulation part 7 refers to an insulation structure that penetrates the chassis 1 and is fixedly connected to the chassis 1. It can be made of ceramic or polymer insulating material and is used to block the conductive path between the energized electrode 3 and the chassis 1. The secondary insulation part 8 refers to an insulation structure that is disposed above the chassis 1 and fixedly connected to the chassis 1. It can be made of ceramic or polymer insulating material and is used to isolate the contact between the support electrode 4 and the chassis 1.

[0034] The portion of the energized electrode 3 located above the chassis 1 is provided with an energized electrode clamping part 31. Above the energized electrode clamping part 31 is a clamping flap, which clamps the silicon core 9. The silicon core 9 is a solid silicon core. The energized electrode clamping part 31 is located on the main insulation part 7. The supporting electrode 4 is located above the chassis 1 and is provided with a supporting electrode clamping part 41. A clamping clip is provided above the supporting electrode clamping part 41, and the clamping clip clamps the silicon core 9. The supporting electrode clamping part 41 is provided on the secondary insulation part 8.

[0035] Among them, the energized electrode clamping part 31 refers to the clamping component fixed to the top of the main insulating part 7, which can be made of copper or graphite, and is used to clamp the silicon core 9 and conduct electricity.

[0036] Among them, the supporting electrode clamping part 41 refers to the clamping component fixed to the top of the secondary insulating part 8. Specifically, it can be made of non-metallic materials such as alumina, silicon nitride, quartz, or silicon carbide, and is used to clamp the silicon core 9 and prevent the metal material from directly contacting the silicon core 9.

[0037] Adjacent silicon cores 9 are fixedly connected sequentially by upper connecting rod 5 and lower connecting rod 6; the fixed connection can be achieved by the upper connecting rod 5 and lower connecting rod 6 being sleeved on the energized electrode 3 or the supporting electrode 4. For example... Figure 4 As shown, the upper connecting rod 5 is sleeved on the energized electrode 3 or the supporting electrode 4. The fixed connection method is not limited here, as long as the two are fixedly connected.

[0038] Specifically, after the silicon core 9 is installed in the electrode clamping part, the current path passes sequentially through the energized electrode 3, the support electrode pair, and the connecting rod, forming a multi-stage series stable circuit. The number of support electrode pairs n can be adjusted according to actual needs; for example, when n is 3, an extended layout of six support electrodes 4 is formed.

[0039] Compared to existing technologies, traditional solutions establish a circuit for every two energized electrodes 3. This solution achieves built-in series connection through the integrated design of electrodes and connecting rods. In existing technologies, each pair of electrodes requires independent cooling; this solution reduces the total cooling water circulation volume by decreasing the number of energized electrodes 3. Traditionally, the graphite clamping part is in direct contact with the silicon core 9; in this solution, the supporting electrode 4 uses insulating material to isolate conductive components, effectively blocking the diffusion of contaminating elements. Existing startup methods are limited by the paired configuration of electrodes; this solution's combined structure of supporting electrode pairs allows for staged startup.

[0040] The supporting electrode clamping part 41 is a contact component used to fix the silicon core 9. This component is in direct contact with the surface of the silicon core 9 and bears high-temperature loads. Specifically, it can be achieved using a high-purity alumina sintered body with a purity higher than 99.5%, whose surface forms a dense oxide layer at high temperatures; it can be achieved using fused silica processed parts, which remain inactive at silicon deposition temperatures; it can be achieved using a dense silicon nitride bulk body prepared by hot pressing sintering, which has excellent thermal shock resistance; or it can be achieved using a silicon carbide coating prepared by chemical vapor deposition, which has a similar coefficient of thermal expansion to the silicon core 9. These materials can maintain structural stability at high temperatures, avoiding impurity precipitation due to material decomposition, while maintaining sufficient mechanical strength to clamp the silicon core 9.

[0041] Compared to existing technologies, the graphite material used in the traditional support electrode clamping part 41 continuously releases carbon elements at high temperatures. Carbon atoms diffuse into the silicon deposition layer through the gas phase, leading to excessive carbon content in the polycrystalline silicon. Meanwhile, copper clamping parts experience trace copper ion migration at high temperatures, contaminating the silicon crystal structure. The materials selected in this solution are chemically inert within the silicon deposition temperature range, eliminating both the risk of carbon release and the generation of metal contamination sources.

[0042] Example 2: A reduction furnace base includes multiple sets of the above-mentioned reduction furnace chassis electrode assemblies. Each set of reduction furnace chassis electrode assemblies includes n pairs of supporting electrodes, where n is an integer from 0 to 3. At least two sets of electrode assemblies have different numbers of supporting electrode pairs. Among them, the electrode assembly of the reduction furnace chassis is arranged in multiple radial layers on the reduction furnace chassis, with the first distribution layer, the second distribution layer, the third distribution layer and the outermost distribution layer arranged sequentially outward from the center of the chassis. 1) Taking a 24-pair rod reduction furnace as an example, the original electrode holder 10 required 48 energized electrodes 3, but now only 15 are needed. The number of electrode pairs n supported by each group of electrode assemblies in the first distribution layer is 0, that is, the energized electrodes 3 are distributed in electrode holders 10 on the 1st / 3rd / 5th / 7th / 8th (e.g., ...). Figure 1 The starting point of each distribution layer electrode is shown as electrode seat 10 (the second distribution layer's electrode assembly supports 1 electrode pair n), meaning the energized electrode 3 is distributed in electrode seats 1 / 4 / 8 / 12 / 16 (the third distribution layer's electrode assembly supports 3 electrode pairs n), meaning the energized electrode 3 is distributed in electrode seats 1 / 8-9 / 16 / 24 (the number is reduced by 68.75%). See the diagram for the distribution of 24 rod electrodes. Figure 2 .

[0043] 1) Taking a 40-pair rod reduction furnace as an example, the original electrode holder 10 required 80 energized electrodes 3, but now it requires 22. The number of electrode pairs n supported by each group of electrode assemblies in the first distribution layer is 0, that is, the energized electrodes 3 are distributed in electrode holders 10 on the 1st / 3rd / 5th / 7th / 8th (e.g., ...). Figure 7The starting point of each distribution layer electrode is shown as electrode holder 10 (the second distribution layer's electrode assembly supports 1 electrode pair n, i.e., energized electrode 3 is distributed in electrode holders 1 / 4 / 8 / 12 / 16 10). The third distribution layer's electrode assembly supports 2 electrode pairs n, i.e., energized electrode 3 is distributed in electrode holders 1 / 6 / 12-13 / 18 / 24 10. The fourth distribution layer's electrode assembly supports 3 electrode pairs n, i.e., energized electrode 3 is distributed in electrode holders 1 / 8 / 16-17 / 24 / 32 10. This is mainly because the length of the silicon core 9 limits the power supply voltage from increasing further; further increases pose a risk of insulation breakdown. See the diagram for the distribution of 48 rod electrodes. Figure 6 .

[0044] By reducing the number of electrode holders 10, the welding workload and processing costs of the equipment are reduced; the amount of electrodes used is reduced, saving costs, and the reduction of copper electrodes also reduces metal ion contamination, further improving the purity of electronic-grade polycrystalline silicon; reducing the use of graphite chucks and graphite holders reduces the diffusion of carbon atoms in graphite, increasing the yield and purity of electronic-grade polycrystalline silicon. The amount of electrode cooling water used is reduced, decreasing heat loss within the furnace, while also reducing the power required to provide cooling water, saving energy.

[0045] The electrode distribution of other reduction furnaces is also done in this way, and the number of supporting electrode pairs n can be modified according to the type of reduction furnace.

[0046] The startup method, coordinated with the aforementioned distribution of energized electrodes 3, involves first activating the first layer of silicon cores 9, with each pair of rods individually started at a high voltage of 10KV, generating a heating power of approximately 120kW. At this point, the furnace temperature rapidly rises to 500℃, activating the second layer. When the furnace temperature reaches approximately 600℃, the third layer of silicon cores 9 is activated; and when the furnace temperature reaches approximately 800℃, the fourth layer of silicon cores 9 is activated. The reduction furnace is then started gradually (with a short interval of approximately 2 minutes between each cycle of silicon cores 9). The startup process is stable, vibration is reduced, and the power supply is stable and highly safe.

[0047] Example 3: The difference from Example 1 is that the chassis 1 is provided with a mounting hole that penetrates the bottom of the chassis 1. A secondary insulating part 8 is installed in the mounting hole. A supporting electrode clamping part 41 is installed in the secondary insulating part 8. The supporting electrode clamping part 41 clamps the silicon core 9. The silicon core 9 is a hollow silicon core. The hollow silicon core can serve as a channel for the reaction gas to enter and exit, reducing the need for opening holes on the chassis 1.

[0048] Through the above technical solutions, this application achieves simplified electrode assembly structure, reduced complexity of sealing and cooling systems, reduced cooling water circulation energy consumption, improved energy utilization efficiency, increased purity of polysilicon products, and shortened reduction furnace preheating time by supporting flexible configuration of electrode pairs and asymmetric start-up mode.

Claims

1. A reduction furnace base, characterized in that, It includes a chassis and multiple sets of electrode assemblies; the electrode assembly includes an energized electrode, a supporting electrode, an upper connecting rod, and a lower connecting rod. There are two energized electrodes and the number of supporting electrodes is 2n. Two adjacent supporting electrodes are combined to form a supporting electrode pair. The number of supporting electrode pairs is n, where n is an integer from 0 to 3. One end of each of the energized electrode and the supporting electrode is fixedly connected to the chassis. The end of the energized electrode and its adjacent supporting electrode away from the chassis is fixedly connected by the upper connecting rod. The lower ends of the two inner supporting electrodes are fixedly connected by the lower connecting rod. The upper ends of the adjacent supporting electrodes are fixedly connected by the upper connecting rod. The energized electrode and the supporting electrode form a series circuit through the upper and lower connecting rods.

2. The reduction furnace base according to claim 1, characterized in that, The energized electrode includes a main-stage insulating part that penetrates the chassis. The chassis is provided with an electrode seat that passes through the chassis. The main-stage insulating part is inserted into the electrode seat. The portion of the energized electrode located above the chassis is provided with an energized electrode clamping part, which clamps the silicon core and is disposed on the main stage insulation part.

3. The reduction furnace base according to claim 2, characterized in that, The chassis is provided with mounting holes that do not penetrate the bottom of the chassis. A secondary insulating part is installed in the mounting holes, and a supporting electrode clamping part is installed in the secondary insulating part. The supporting electrode clamping part clamps a solid silicon core.

4. A reduction furnace base according to claim 2, characterized in that, The chassis is provided with mounting holes that penetrate the bottom of the chassis. A secondary insulating part is installed in the mounting holes, and a supporting electrode clamping part is installed in the secondary insulating part. The supporting electrode clamping part clamps the hollow silicon core.

5. A reduction furnace base according to claim 2, characterized in that, The adjacent silicon cores are fixedly connected in sequence by the upper connecting rod and the lower connecting rod.

6. A reduction furnace base according to claim 3, characterized in that, The material of a single supporting electrode clamping part is any one of alumina, quartz, silicon nitride, and silicon carbide.

7. A reduction furnace base according to claim 2, characterized in that, The material of a single energized electrode clamping part is either copper or graphite.

8. A reduction furnace base according to any one of claims 1-7, characterized in that, At least two sets of the electrode assemblies have different numbers of support electrode pairs.

9. A reduction furnace base according to any one of claims 1-7, characterized in that, The electrode assembly is arranged radially in multiple layers on the chassis, with a first distribution layer, a second distribution layer, and a third distribution layer arranged sequentially outward from the center of the chassis. Each group of electrode assemblies in the first distribution layer does not include supporting electrode pairs; Each group of electrode assemblies within the second distribution layer includes a pair of supporting electrodes; Each group of electrode assemblies in the third distribution layer includes two pairs of supporting electrodes.

10. A reduction furnace base according to any one of claims 1-7, characterized in that, The electrode assembly is arranged radially in multiple layers on the chassis, consisting of a first distribution layer, a second distribution layer, a third distribution layer, and an outer distribution layer arranged sequentially outward from the center of the chassis. Each group of electrode assemblies in the first distribution layer does not include supporting electrode pairs; Each group of electrode assemblies within the second distribution layer includes a pair of supporting electrodes; Each group of electrode assemblies in the third distribution layer includes three pairs of supporting electrodes; Each group of electrode assemblies within the outer distribution layer includes three pairs of supporting electrodes.

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