阅读说明：本技术 一种硅极板及其制备方法 (silicon polar plate and preparation method thereof ) 是由 朱景兵 施正荣 于 2018-06-07 设计创作，主要内容包括：本发明公开了一种硅极板及其制备方法,所述硅极板采用掺杂导电的晶体硅材料制成,具有内部冷却介质流道、正面还原剂流道和/或反面氧化剂流道,且所述内部冷却介质流道、正面还原剂流道和/或反面氧化剂流道分别设有与其相连通的硅极板进出口组合；相比于现有技术中的金属极板、石墨极板或复合材料极板,本发明提出的硅极板在寿命、成本、效率以及功率密度上具有更佳的优势,对于燃料电池的大批量产业化进程无疑是具有重大意义和核心推进作用的。(The invention discloses a silicon electrode plate and a preparation method thereof, wherein the silicon electrode plate is made of a doped conductive crystalline silicon material and is provided with an internal cooling medium flow passage, a front reducing agent flow passage and/or a back oxidizing agent flow passage, and the internal cooling medium flow passage, the front reducing agent flow passage and/or the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet-outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage and/or the back oxidizing agent flow passage; compared with a metal polar plate, a graphite polar plate or a composite material polar plate in the prior art, the silicon polar plate provided by the invention has better advantages in service life, cost, efficiency and power density, and has great significance and core propulsion undoubtedly for the large-scale industrialization process of fuel cells.)

1. the silicon electrode plate is characterized in that the silicon electrode plate is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage and a back oxidizing agent flow passage, and the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage.

2. the silicon electrode plate is characterized in that the silicon electrode plate is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage or a back oxidizing agent flow passage, and the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage.

3. The silicon plate of claim 1 or 2, wherein the silicon plate comprises 2 or more than 2 silicon wafers, wherein the silicon wafers have single-sided or double-sided flow channels;

The surface areas of the silicon wafers, which do not cover the flow channels, are connected and stacked into a whole by adopting a conductive material in a composite mode, an internal flow channel located in the silicon polar plate is formed through the composite connection, and the internal flow channel is used as the internal cooling medium flow channel; and the flow channel positioned on the non-stacking surface of the silicon wafer is used as a reducing agent flow channel or an oxidizing agent flow channel.

4. The silicon plate of claim 1 or 2, wherein the doped conductive crystalline silicon material has a resistivity not higher than 0.1 Ω.

5. the silicon plate of claim 1 or 2, wherein the doped conductive crystalline silicon material is a single crystal or a polycrystalline doped silicon wafer.

6. The silicon plate of claim 5, wherein the silicon wafer has a thickness in the range of 0.2-5mm and a size in the range of 50-300 mm.

7. The method for preparing a silicon plate as claimed in any one of claims 1 to 6, wherein the flow channel or the inlet and outlet combination is processed on one side or both sides of the silicon wafer by etching process or laser process or screen printing process; and 2 or more than 2 silicon chips are compositely connected and stacked into a whole by adopting a conductive material, an internal flow channel positioned in the silicon polar plate is formed by the composite connection, and the internal flow channel is used as the internal cooling medium flow channel.

8. the method for preparing a silicon plate according to claim 1, comprising the following steps:

A10) preparing a first silicon chip and a second silicon chip;

A20) Respectively manufacturing conductive material layers on the two sides of the first silicon wafer and the second silicon wafer through a screen printing process;

A30) the conductive material layer is simultaneously used as a mask layer, a back first internal cooling medium channel and a front reducing agent channel are respectively manufactured on the two sides of the first silicon wafer through an alkali solution corrosion process, and a front second internal cooling medium channel and a back oxidizing agent channel are respectively manufactured on the two sides of the second silicon wafer;

A40) Respectively manufacturing a first inlet-outlet combination and a second inlet-outlet combination on the first silicon chip and the second silicon chip by adopting a laser process;

A50) Laminating the first silicon wafer and the second silicon wafer, sintering at high temperature, melting the conductive material layers of the first silicon wafer and the second silicon wafer which are mutually contacted, and compositely connecting the two silicon wafers into a whole; the first internal cooling medium flow channel and the second internal cooling medium flow channel are correspondingly matched and form the internal cooling medium flow channel through the composite connection; and the first inlet and outlet combination and the second inlet and outlet combination are respectively matched correspondingly and form the silicon electrode plate inlet and outlet combination through the composite connection.

9. the method for preparing a silicon plate according to claim 2, comprising the following steps:

A10'), preparing a first silicon wafer and a second silicon wafer;

a20'), respectively manufacturing a conducting material layer on the single side of the first silicon wafer and the double sides of the second silicon wafer by a screen printing process;

a30'), the conductive material layer is simultaneously used as a mask layer, a front side or a back side first internal cooling medium flow passage is respectively manufactured on one side of the first silicon chip by an alkali solution corrosion process, and a back side or a front side second internal cooling medium flow passage and a front side reducing agent flow passage or a back side oxidizing agent flow passage are respectively manufactured on the two sides of the second silicon chip;

A40'), respectively manufacturing a first inlet-outlet combination and a second inlet-outlet combination on the first silicon chip and the second silicon chip by adopting a laser process;

A50'), laminating the first silicon wafer and the second silicon wafer, sintering at high temperature, melting the conductive material layers of the first silicon wafer and the second silicon wafer which are mutually contacted, and compositely connecting the two silicon wafers into a whole; the first internal cooling medium flow channel and the second internal cooling medium flow channel are correspondingly matched and form the internal cooling medium flow channel through the composite connection; and the first inlet and outlet combination and the second inlet and outlet combination are respectively matched correspondingly and form the silicon electrode plate inlet and outlet combination through the composite connection.

10. The method for manufacturing a silicon plate according to claim 8 or 9, wherein the conductive material is a metal conductive material having a eutectic bonding effect with a silicon material, and the heating temperature for sintering at a high temperature is close to or equal to the eutectic temperature of the silicon material and the metal conductive material.

Technical Field

the invention belongs to the field of silicon materials, and particularly relates to a silicon polar plate and a preparation method thereof.

Background

A fuel cell is a chemical device that directly converts chemical energy of fuel into electrical energy, and is also called an electrochemical generator. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, is not limited by Carnot cycle effect, and has high energy conversion rate; the reaction product of the fuel cell which adopts hydrogen as fuel is water, so that the method is environment-friendly and can realize zero-pollution emission theoretically; in addition, the fuel cell has no mechanical transmission part, few moving parts and low noise during working; the fuel cell has the advantages of high specific energy, high reliability, wide fuel range, short starting time, small volume, convenient carrying and the like. It follows that fuel cells are currently the most promising power generation technology from the viewpoint of energy conservation and ecological environment conservation.

structurally, a fuel cell generally includes an Electrode (Electrode), an Electrolyte Membrane (Electrolyte Membrane), and a Current Collector (Current Collector); among them, the electrode of the fuel cell is an electrochemical reaction site where oxidation reaction of fuel and reduction reaction of oxidant occur, and in order to promote the reaction, a catalyst is generally further provided on the electrode; the main function of the electrolyte membrane is to separate the oxidant and the reductant and to conduct ions; the current collector, also commonly called Bipolar Plate (Bipolar Plate), is an important performance element in the fuel cell stack, and the Bipolar Plate is responsible for distributing fuel and air to the surfaces of the cathode and anode and for dissipating heat of the stack, and is also a key component responsible for connecting the single cells in series to form the stack, and mainly plays a role in dividing the oxidant, the reducing agent and the coolant and collecting current, and has a great weight on the aspects of the mass, the volume, the cost, the reliability, the power density and the like of the fuel cell stack, and the cost occupies 20-60% of the cost of the whole fuel cell. Therefore, the development of high-performance, low-cost bipolar plate materials is of great significance for large-scale commercial application of fuel cells. The development of the bipolar plate material occupies 40-60% of the development cost of the fuel cell, and on the other hand, the bipolar plate is proved to be the key factor determining the industrialization of the fuel cell.

The research proves that the bipolar plate has the following characteristics: good air blocking function; better heat-conducting property; lower bulk and contact resistance; the corrosion resistance is strong; light weight, high strength, suitability for batch processing and the like.

Disclosure of Invention

in view of the above, the present invention provides a silicon electrode plate and a method for manufacturing the same, which has a good gas barrier function; better heat-conducting property; lower bulk and contact resistance; the corrosion resistance is strong; light weight, high strength, suitability for batch processing and the like; compared with the metal polar plate, the graphite polar plate or the composite material polar plate in the prior art, the invention has better advantages in service life, cost, efficiency and power density, and undoubtedly has great significance and core propulsion effect on the large-scale industrialization process of the fuel cell.

before the technical scheme of the invention is proposed, the applicant finds some suspected prior technical schemes close to the invention through careful batch search, and the applicant performs careful reading and key analysis:

the literature on periodicals describes: the material silicon has the characteristics of low gas permeability, high heat conductivity coefficient, easy processing and the like, is an ideal substrate material in the manufacture of micro fuel cells, and can obtain electric conductivity and better stability and corrosion resistance by plating metal (usually noble metal) on the surface of the silicon. In 2000, Kelly and Meyers first published phases for fabricating micro fuel cells on silicon substratesand (4) relevant documents. Silicon has since been a major development in micro fuel cells. The Kim uses silicon as a substrate to manufacture a micro fuel cell, the size of a flow channel of the micro fuel cell is 400 micrometers (width) and 230 micrometers (depth), and heat-resistant glass with the thickness of 500 micrometers is added on the back of a silicon micro bipolar plate, so that the physical strength of the micro fuel cell is enhanced, and the defect that a silicon wafer is fragile is overcome; and gold is plated on the silicon bipolar plate, so that the silicon bipolar plate has better stability, and the actual power density is 203mW/cm when the output voltage is 0.6V²the maximum power density can reach 261mW/cm²The volume specific power density of the battery is 360mW/cm³However, the silicon material as the bipolar plate material has some disadvantages, such as the need of plating with noble metal to collect the current, which not only increases the production process, but also increases the material cost. Through the careful analysis of the applicant, the technology utilizes the characteristics of air tightness, heat conductivity and easy fine processing of silicon, so that a silicon wafer is directly used as a substrate of a fuel cell, a metal layer for collecting current is formed on the silicon substrate, the current generated by an electrode is collected and flows out of the cell along the direction parallel to the surface of the silicon substrate, and the structure can only be made into the fuel cell with a small area because the current is conducted along the metal layer film and cannot be stacked in multiple layers; meanwhile, because a structure for providing cooling medium flow cannot be arranged inside the silicon substrate structure, the technical scheme of adopting silicon material as the fuel cell polar plate substrate can only be applied to micro fuel cell products for a long time.

As described above, the applicant has found through further search that the prior art solution of applying silicon material to fuel cell is suspected to be disclosed, and in order to better illustrate the technical solution of the present invention, the applicant further specifically lists the following patent documents to illustrate the difference between the technical solutions and the present invention:

1. If the chinese patent with the publication number of CN100397687C discloses a cathode flow field plate of a self-breathing micro proton exchange membrane fuel cell and a manufacturing method thereof, a new structure processed by the MEMS technology is adopted, and specifically, the following are proposed: the flow field plate is structurally characterized in that a cathode flow field is processed into a double-layer composite hollow structure on a silicon sheet material with the thickness of about 300-; the silicon polar plate of the method is used as a cathode substrate structure of the micro fuel cell, a precious metal conducting layer is required to be arranged on the silicon substrate to realize the current collecting function required by the polar plate structure, the preparation process is complex, the material cost is high, a cooling water flow channel cannot be arranged, and only the micro fuel cell can be manufactured;

2. the invention patent with the publication number of CN101894954B discloses a method for packaging a microminiature fuel cell based on a normal temperature bonding technology, which provides a method for manufacturing a cathode plate and an anode plate.A thermal oxidation method is used for growing 50nm silicon dioxide on two sides of a crystal orientation double-sided polished silicon wafer as a stress buffer layer, then LPCVD is used for depositing 160nm silicon nitride as a masking layer, 20nm Cr is sputtered on the front side as an adhesion layer, 0.2 micron Au is sputtered on the front side as a current collection layer, then the exposed silicon nitride is removed by reactive ion etching after a flow field structure pattern is photoetched, and a photoresist colloid is removed; then, using KOH solution and ultrasonic wave to corrode the silicon wafer, and stopping when corrosion surfaces on two sides meet to form a through inlet, outlet and through hole; finally, removing the silicon nitride exposed on the front surface by reactive ion etching, and removing the silicon dioxide bonded on the front surface by hydrofluoric acid aqueous solution; the silicon electrode plate of the method is also used as an electrode plate substrate structure of the micro fuel cell, a precious metal conducting layer (Au or Pt, and Cr is also needed to be arranged as an adhesion layer) is needed to be arranged on the silicon substrate to realize the current collecting function required by the electrode plate structure, the preparation process is complex, the material cost is high, a cooling water flow channel cannot be arranged, and only the micro fuel cell can be manufactured;

3. The invention patent with publication number CN101867052A discloses a spoke type self-breathing micro fuel cell and a preparation method thereof, wherein silicon wafers are used as a cathode plate and an anode plate, and the specific process is as follows: cleaning a silicon wafer, preparing a silicon nitride film serving as a corrosion mask on the surface of the silicon wafer by using a low-pressure chemical vapor deposition method, and forming a mask pattern on the film by using a photoetching technology so as to realize the purpose of selective corrosion; carrying out anisotropic corrosion on a silicon wafer by adopting a 40% KOH solution, removing a residual silicon nitride film on the surface of the silicon wafer by utilizing a reactive ion etching method, forming an inlet and outlet channel with steep side walls on the surface of the silicon wafer by adopting a laser processing technology, and forming a Ti/Au metal layer on the corrosion surface of the silicon wafer by utilizing a magnetron sputtering technology for collecting and conducting current; similarly, the silicon plate of the method is also used as a plate substrate structure of the micro fuel cell, and not only a precious metal conducting layer (Ti/Au) is required to be arranged on the silicon substrate to realize the current collecting function required by the plate structure, the preparation process is complex, the material cost is high, but also a cooling water flow channel cannot be arranged, and only the micro fuel cell can be manufactured;

4. The invention patent with the publication number of CN100483829C discloses a stacked silicon-based micro fuel cell set and a manufacturing method thereof, wherein a silicon substrate is adopted, and specifically an etching method of a silicon polar plate is disclosed, silicon dioxide grows on two sides of a crystal-oriented double-sided polished silicon wafer by a thermal oxidation method, then LPCVD0.1 micron silicon nitride is used as a masking layer, and photoetching exposed silicon nitride is removed by reactive ion etching after a flow field structure pattern is photoetched, and a photoresist is removed; then, using KOH solution and ultrasonic wave to corrode the silicon wafer, and stopping when corrosion surfaces on two sides meet to form a through inlet, outlet and through hole; similarly, the silicon electrode plate of the method is also used as a substrate structure of the micro fuel cell, and not only a precious metal conducting layer (Ti/Pt) is required to be arranged on the silicon substrate to realize the current collecting function required by the electrode plate structure, the preparation process is complex, the material cost is high, but also a cooling water flow channel cannot be arranged, and only the micro fuel cell can be manufactured;

5. The invention patent with the publication number of CN100369304C discloses a preparation method of a catalytic electrode for a silicon-based micro direct methanol fuel cell, and particularly discloses a method for preparing a catalytic electrode for a silicon-based micro direct methanol fuel cell, which comprises the steps of cleaning a silicon wafer with the resistivity of 0.012-0.013 omega cm and the P-type or N-type crystal orientation of <100>, oxidizing to generate a silicon dioxide layer with the thickness of 1.0-1.5 microns, forming a flow field pattern by adopting a photoetching technology, and corroding a channel flow field on the silicon wafer by adopting a wet corrosion technology, wherein the corrosion depth is 150-240 microns; and finally, forming porous silicon on the surface of the silicon wafer by an electrochemical method, and greatly increasing the effective reaction area of the catalyst on the surface of the porous silicon after the catalyst is deposited on the surface of the porous silicon. In the fuel cell, a silicon chip is used as a carrier of a catalytic electrode material of the micro fuel cell, and the technical problem to be solved by using crystalline silicon to manufacture a polar plate and the technical scheme adopted by the invention are different.

in conjunction with the above, these prior doubts propose the technical solutions of using silicon material for fuel cells, the applicant found that these technical solutions either only use the silicon plate as the substrate support of the plate component thereof, and need to coat the silicon plate with a material such as noble metal to be actually used for current collection of the plate component of the fuel cell, as described in the above-mentioned journal, 1.CN100397687C, 2.CN101894954B, 3.CN101867052A, 4, CN 100483829C; or the silicon wafer is made into a porous silicon structure and used as a catalyst carrier and an electrode material of a fuel cell, such as 5.CN 100483829C; the prior arts have a common feature that the technical solutions that silicon is used as a substrate of a polar plate or an electrode material are all limited to be applied to micro fuel cells, the micro fuel cells generally adopt 1 or at most 2 fuel cell units, the output power is generally between milliwatt and dozens of watt, and the silicon substrate structure cannot be provided with a cooling water channel, so that the heat dissipation performance cannot be guaranteed; the applicant finds that none of the technical proposals of applying the technical solution concept to the non-micro-scale industrial fuel cell has been proposed, and after the deep analysis of the applicant, the inspiration of the technical methods for making the silicon substrate by using the silicon wafer proposed by the prior art comes from the silicon chip processing technology in the electronic industry, in particular, the MEMS processing technology, which is applied to the micro-scale industrial fuel cell for making the silicon substrate or the porous silicon electrode, while the non-micro-scale industrial fuel cell has a stack structure in which a plurality of fuel cell units are connected in series, firstly the silicon substrate cannot provide enough mechanical supporting force, secondly, precious metal is plated on the silicon electrode plate substrate to realize the current collecting function, and if the non-micro-scale industrial fuel cell is made by using the MEMS processing technology, the cost is too high, has no competitive advantage with metal polar plates or graphite polar plates; more importantly, as mentioned above, these solutions collect the current generated by the electrodes and flow out of the cell in the direction parallel to the silicon substrate, and this structure can only be made into a fuel cell with a small area because it conducts the current along the metal layer film, and cannot be stacked in multiple layers; and the electric pile structure can generate heat in the working process due to high output power, so the polar plate needs to be provided with a cooling water channel besides an oxidant channel and a reducing agent channel. On this basis, therefore, the person skilled in the art would not have any motivation to apply silicon materials to industrial fuel cells on a non-miniature scale.

Through the understanding of the fuel cell and the research, exploration and analysis experiences of the silicon material for decades, the inventor of the present application finds that the silicon material can be completely directly used as a silicon pole plate of the fuel cell after specific selection and design, and compared with a metal pole plate, a graphite pole plate or a composite material pole plate in the prior art, the silicon pole plate of the present invention obtains a surprisingly prominent technical effect, and the main adopted technical scheme is as follows:

a silicon electrode plate is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage and a back oxidizing agent flow passage, and the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage.

a silicon electrode plate is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage or a back oxidizing agent flow passage, and the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage.

Preferably, the silicon plate comprises 2 or more than 2 silicon wafers, wherein the silicon wafers are provided with single-sided or double-sided flow channels; the surface areas of the silicon wafers, which do not cover the flow channels, are connected and stacked into a whole by adopting a conductive material in a composite mode, an internal flow channel located in the silicon polar plate is formed through the composite connection, and the internal flow channel is used as the internal cooling medium flow channel; and the flow channel positioned on the non-stacking surface of the silicon wafer is used as a reducing agent flow channel or an oxidizing agent flow channel.

Preferably, the resistivity of the doped conductive crystalline silicon material is not higher than 0.1 Ω.

Preferably, the doped conductive crystalline silicon material is a monocrystalline or polycrystalline doped silicon wafer.

Preferably, the silicon wafer has a thickness in the range of 0.2 to 5mm and a size in the range of 50 to 300 mm.

preferably, in the preparation method of the silicon electrode plate, the flow channel or the inlet and outlet combination is processed on one side or both sides of the silicon wafer by adopting an etching process or a laser process or a screen printing process; and 2 or more than 2 silicon chips are compositely connected and stacked into a whole by adopting a conductive material, an internal flow channel positioned in the silicon polar plate is formed by the composite connection, and the internal flow channel is used as the internal cooling medium flow channel.

Preferably, the preparation method of the silicon plate comprises the following operation steps:

A10) Preparing a first silicon chip and a second silicon chip;

A20) Respectively manufacturing conductive material layers on the two sides of the first silicon wafer and the second silicon wafer through a screen printing process;

A30) the conductive material layer is simultaneously used as a mask layer, a back first internal cooling medium channel and a front reducing agent channel are respectively manufactured on the two sides of the first silicon wafer through an alkali solution corrosion process, and a front second internal cooling medium channel and a back oxidizing agent channel are respectively manufactured on the two sides of the second silicon wafer;

A40) respectively manufacturing a first inlet-outlet combination and a second inlet-outlet combination on the first silicon chip and the second silicon chip by adopting a laser process;

A50) Laminating the first silicon wafer and the second silicon wafer, sintering at high temperature, melting the conductive material layers of the first silicon wafer and the second silicon wafer which are mutually contacted, and compositely connecting the two silicon wafers into a whole; the first internal cooling medium flow channel and the second internal cooling medium flow channel are correspondingly matched and form the internal cooling medium flow channel through the composite connection; and the first inlet and outlet combination and the second inlet and outlet combination are respectively matched correspondingly and form the silicon electrode plate inlet and outlet combination through the composite connection.

preferably, the preparation method of the silicon plate comprises the following operation steps:

a10'), preparing a first silicon wafer and a second silicon wafer;

A20'), respectively manufacturing a conducting material layer on the single side of the first silicon wafer and the double sides of the second silicon wafer by a screen printing process;

A30'), the conductive material layer is simultaneously used as a mask layer, a front side or a back side first internal cooling medium flow passage is respectively manufactured on one side of the first silicon chip by an alkali solution corrosion process, and a back side or a front side second internal cooling medium flow passage and a front side reducing agent flow passage or a back side oxidizing agent flow passage are respectively manufactured on the two sides of the second silicon chip;

a40'), respectively manufacturing a first inlet-outlet combination and a second inlet-outlet combination on the first silicon chip and the second silicon chip by adopting a laser process;

a50'), laminating the first silicon wafer and the second silicon wafer, sintering at high temperature, melting the conductive material layers of the first silicon wafer and the second silicon wafer which are mutually contacted, and compositely connecting the two silicon wafers into a whole; the first internal cooling medium flow channel and the second internal cooling medium flow channel are correspondingly matched and form the internal cooling medium flow channel through the composite connection; and the first inlet and outlet combination and the second inlet and outlet combination are respectively matched correspondingly and form the silicon electrode plate inlet and outlet combination through the composite connection.

Preferably, the conductive material is a base metal conductive material.

preferably, said step a40) is performed before step a30) or before step a 20).

Preferably, said step a40 ') is performed before step a30 ') or before step a20 ').

Preferably, in the present invention, the thickness of the conductive material used for composite connection between silicon wafers is in the micron range, and may be 1-100 microns, or 1-50 microns, or 1-20 microns, and in terms of material selection, the conductive material may be a conductive metal material or a conductive non-metal material such as conductive adhesive, and since the conductive non-metal material of conductive adhesive is difficult to process to the micron thickness, and in the composite connection process, organic solvent generally needs to be removed, which is not beneficial to the implementation of the process, therefore, preferably, the conductive material of the present invention is a metal conductive material; in order to facilitate good composite connection between metal conductive materials and between the metal conductive materials and silicon wafers, preferably, the conductive materials of the invention are metal conductive materials having eutectic bonding effect with silicon materials, that is, when the temperature is equal to or close to eutectic temperature (the eutectic temperature is the temperature when the silicon and the corresponding metal conductive materials are subjected to eutectic reaction), the metal conductive materials and the silicon can be subjected to good eutectic reaction, so that a metal conductive material layer between the silicon wafers and a silicon wafer surface layer in contact with the metal conductive material layer are mutually fused and bonded, and an integral silicon-metal conductive alloy composite structure with firm bonding is formed after cooling, and finally, the excellent composite connection effect between the silicon wafers is realized; particularly preferably, these metallic conductive materials may be in particular: nickel Ni, gold Au, silver Ag, copper Cu, aluminum Al and other materials; the eutectic temperature of silicon and these metal conductive materials is usually significantly lower than the melting temperature of silicon itself or the metal conductive materials themselves, and the eutectic temperature range is usually 500-1000 ℃, and the eutectic temperature with silicon can be determined according to the type of the metal conductive material actually used, and these can be obtained by referring to the related prior art information.

preferably, the depth of the reducing agent flow channel and/or the oxidizing agent flow channel ranges from 50 to 300 micrometers, and the width ranges from 500 to 3000 micrometers.

the invention provides a silicon polar plate directly taking a doped conductive crystalline silicon material as a fuel cell on the basis of dozens of years of research, exploration and analysis experiences of the inventor of the applicant on a silicon material, and provides the structural design of the silicon polar plate, specifically, the silicon polar plate is formed by stacking and compounding two or more than two silicon wafers, an internal flow channel is formed by stacking and compounding, and the internal flow channel can be directly used as a cooling medium flow channel; the silicon pole plate provided by the invention is used as a framework structure in the fuel cell, so that enough mechanical supporting force can be provided, and the silicon pole plate is directly used as a current collecting plate to transmit current in the stacking direction of the fuel cell, so that a metal film layer is not required to be additionally arranged, and a multi-layer stacking structure required by the fuel cell with a galvanic pile structure is realized; the internal flow channel of the silicon polar plate is directly used as a cooling medium flow channel, so that heat generated in the working process of the fuel cell is further effectively and timely conveyed to the outside; therefore, the silicon polar plate provided by the invention can completely meet the requirement of a fuel cell bipolar plate on good gas resistance function; better heat-conducting property; lower bulk and contact resistance; the corrosion resistance is strong; compared with the metal polar plate, the graphite polar plate or the composite material polar plate in the prior art, the silicon polar plate provided by the invention has better advantages in service life, cost, efficiency and power density, and has great significance and core propulsion undoubtedly for the large-scale industrialization process of the fuel cell.

The invention further provides a preferable preparation method of the silicon polar plate, wherein a conductive material layer is manufactured on the surface of the silicon chip, the conductive material layer is preferably made of base metal materials such as nickel, copper and the like, the conductive material layer is used as a mask layer structure in the subsequent corrosion process of the silicon chip, and simultaneously, two silicon chips are compositely connected and stacked into a whole transition bonding structure, the process is the simplest and most effective, the implementation is easy, the process cost is the lowest, and the method is suitable for batch manufacturing and application.

the invention further provides a preferable conductive material for composite connection between silicon wafers, and particularly provides a method for sintering a metal conductive material which has a eutectic bonding effect with a silicon material at a eutectic temperature to be used as a composite material for connecting the silicon wafers, so that the metal conductive material layer between the silicon wafers and the surface layer of the silicon wafer contacted with the metal conductive material layer are mutually fused and bonded, an integral silicon-metal conductive alloy composite structure with firm bonding is formed after cooling, and finally, the excellent composite connection effect between the silicon wafers is realized.

it should be noted that the silicon electrode plate provided by the invention has the excellent characteristics, so that the silicon electrode plate is particularly suitable for being applied to the field of non-miniature fuel cell products with a galvanic pile structure (especially non-miniature fuel cells with output power not lower than 0.1 KW), and has better performance advantages compared with a metal electrode plate, a graphite electrode plate or a composite material electrode plate in the prior art; of course, those skilled in the art can directly apply the silicon plate to the field of micro fuel cells (generally, only 1-2 fuel cell units) according to actual needs, which has some obvious technical advantages in material cost, preparation process, mechanical strength and cooling performance compared with the existing micro fuel cells using silicon as the plate substrate, and these should also fall within the protection scope of the present invention.

it should be noted that the expressions of the front and the back in the entire text of the present invention are only for explaining the position distribution relationship of various flow channels distributed on different surfaces of the silicon wafer, and the front and the back are relative, and the actual directions are different according to different references, which is not taken as the limitation of the present invention on the specific directions.

Drawings

FIG. 1 is a schematic cross-sectional view of a stack structure 100 in accordance with an embodiment of the present invention;

Fig. 2 is a schematic sectional structure view of the middle fuel cell units 100b, 100c, 100d and the end fuel cell units 100a, 100e of example 1 of the invention;

FIG. 3 is a schematic cross-sectional view of the middle silicon plate 110 and the end silicon plates 130 and 130' in example 1 of the present invention;

FIG. 4 is a schematic structural diagram of a reducing agent passage 111 in a silicon plate 110 in the middle of example 1 of the present invention;

FIG. 5 is a flow chart of a process for preparing the silicon plate 110 in the middle of example 1;

FIG. 6 is a flow chart of a process for preparing a middle silicon plate 210 according to example 2 of the present invention;

FIG. 7 is a flow chart of a process for preparing a middle silicon plate 310 according to example 3 of the present invention;

FIG. 8 is a flow chart of a process for preparing a silicon plate 410 in the middle of example 4;

FIG. 9 is a schematic sectional view showing a fuel cell unit 10 of a micro fuel cell in example 5 of the invention;

fig. 10 is a schematic sectional view showing the structure of fuel cells 20a, 20b of a micro fuel cell in example 6 of the invention.

Detailed Description

the embodiment of the invention discloses a silicon electrode plate, which is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage and a back oxidizing agent flow passage, wherein the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage and the back oxidizing agent flow passage.

the embodiment of the invention discloses a silicon electrode plate, which is made of doped conductive crystalline silicon materials and is provided with an internal cooling medium flow passage, a front reducing agent flow passage or a back oxidizing agent flow passage, wherein the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage are respectively provided with a silicon electrode plate inlet and outlet combination communicated with the internal cooling medium flow passage, the front reducing agent flow passage or the back oxidizing agent flow passage.

the embodiment of the invention discloses a preparation method of the silicon polar plate, wherein a flow channel or an inlet-outlet combination is processed on one side or two sides of a silicon wafer by adopting an etching process or a laser process or a screen printing process; 2 or more than 2 silicon chips are compositely connected and stacked into a whole by adopting a conductive material, an internal flow channel positioned in the silicon polar plate is formed by composite connection, and the internal flow channel is used as an internal cooling medium flow channel.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.