CN105036062B - A kind of manufacture method of MEMS lithium batteries - Google Patents

Abstract

The invention discloses a method for manufacturing a MEMS lithium battery, which comprises separately manufacturing a first casing on which a cavity is formed and a positive electrode of the battery is integrally formed in the cavity, and a second casing made of the same material as the first casing , forming a cavity connected to the first shell on it, and integrally forming the negative electrode of the battery in the cavity; then packaging the first shell and the second shell together to form a battery. The preparation process of the lithium battery of the present invention is simple, can be produced in batches, and reduces production costs; can greatly improve the consistency and reliability of battery preparation; can make the electrode change from a two-dimensional structure to a three-dimensional structure, greatly increasing the surface area of the electrode, reducing The charge transfer resistance increases the number of ion migration, which greatly improves the energy density and power density of the battery; it can shorten the ion migration distance and shorten the charging time of the battery.

Description

A kind of manufacturing method of MEMS lithium battery

technical field

The invention relates to the field of battery manufacturing, and more particularly to a method for manufacturing a MEMS lithium battery.

Background technique

Micro-Electro-Mechanical System (MEMS), also known as micro-electro-mechanical system, micro-system or micro-machine, is developed on the basis of microelectronic technology (semiconductor manufacturing technology), which integrates lithography, corrosion, High-tech electromechanical devices manufactured by thin film, LIGA, silicon micromachining, non-silicon micromachining and precision machining technologies.

MEMS integrates micro-sensors, micro-actuators, micro-mechanical structures, micro-power and micro-energy sources, signal processing and control circuits, high-performance electronic integrated devices, interfaces, and communications. It is a revolutionary new technology and is widely used in high-tech In the industry, its system size is several millimeters or even smaller, and its internal structure is generally on the order of microns or even nanometers. MEMS can be produced in large quantities. Common products include MEMS accelerometers, MEMS microphones, micro motors, micro pumps, micro vibrators, MEMS optical sensors, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, MEMS gas sensors, etc., and their Integrated products.

The development of MEMS technology has brought about many changes in technology and materials. For many independent MEMS devices, it is difficult to provide energy due to their extremely small size. As a branch of MEMS technology, the current micro energy part mainly includes fuel Battery. However, fuel cells still have some unsatisfactory aspects in supplementing fuel, generating gaseous products, and service life.

Contents of the invention

In view of this, one of the main purposes of the present invention is to provide a MEMS lithium battery and a manufacturing method thereof, so that the lithium battery can be manufactured using a micro-mechanical manufacturing process.

In order to achieve the above object, the invention provides a method for preparing a MEMS lithium battery, comprising the following steps:

Using a semiconductor material as the base of the first shell, forming a first lead-out electrode, a first three-dimensional column array, and a first cell body thereon, wherein the first three-dimensional column array is located in the first cell body;

modifying and fixing the first nanomaterial on the surface of the first three-dimensional column array as the positive electrode;

Using the same method, a second housing containing the negative electrode is prepared, a second lead-out electrode, a second three-dimensional column array, and a second pool are formed on the second housing, and the second three-dimensional column array is formed on the surface of the second three-dimensional column array modifying and fixing the second nanomaterial as a negative electrode, wherein the second three-dimensional column array is located in the second cell body, and the second cell body is aligned with the first cell body to form an accommodation cavity, the The first three-dimensional column array and the second three-dimensional column array are staggered from each other;

Aligning and packaging the first casing and the second casing to form a casing of the MEMS lithium battery.

Wherein, after the step of aligning and packaging the first shell and the second shell, it also includes injecting electrolyte from the reserved sample injection hole, and sealing the sample injection hole after the electrolyte fills the cell body, thereby obtaining The steps of the MEMS lithium battery.

Wherein, after the step of modifying the surface of the second three-dimensional column array and fixing the second nanomaterial as the negative electrode, before the step of aligning and packaging the first shell and the second shell, the first A step of filling colloidal electrolyte in the shell and the cell body on the second shell.

Wherein, the first/second pool body and the reserved columns located in the first/second pool body are formed on the first/second housing by a deep etching or chemical etching process, and the first/second pool body is formed by photolithography The process forms the first/second three-dimensional column array on the reserved column.

Wherein, the semiconductor material is silicon-based, carbon-based or gallium arsenide material.

Wherein, the step of forming the first/second lead-out electrodes on the substrate includes the step of forming an Au/Cr metal layer on the substrate as a mask, wherein the thickness of the Au layer is 100-500 nm, and the thickness of the Cr layer is The thickness is 10-50nm.

Wherein, the thickness of the Au layer is 200nm, and the thickness of the Cr layer is 20nm.

Wherein, the preparation of the first casing containing the positive electrode and the second casing containing the negative electrode is not in any order.

Wherein, in the step of packaging the first casing and the second casing, a bonding sealing or BCB sealing process is used.

Wherein, before forming the first extraction electrode and/or the second extraction electrode, a first boss is formed on the upper surface of the base of the first casing and/or the second casing by deep etching or chemical etching process and/or the second boss, so that in the subsequent etching process, the first boss and the second boss are used to form an interdigitated structure.

Based on the above technical scheme, it can be seen that the MEMS lithium battery of the present invention has the following advantages and beneficial effects: (1) The present invention uses silicon as the substrate, and utilizes the bulk silicon process to process the positive electrode and the negative electrode with a three-dimensional body structure on two silicon substrates respectively As well as the battery cell body, its preparation process is relatively simple, and can be mass-produced to reduce production costs; (2) On different silicon substrates, the positive electrode and the negative electrode are prepared separately, which can avoid the modification and fixation of the positive electrode material and the negative electrode material. Short-circuiting the electrodes can greatly improve the consistency and reliability of battery preparation; (3) A micro-silicon pillar array is processed on the silicon substrate as a support for the electrodes (positive and negative electrodes), which can change the electrode from a two-dimensional structure to a three-dimensional structure , greatly increased the surface area of the electrode, increased the number of ion migration, and greatly increased the energy density and power density of the battery; (4) The positive and negative electrodes form an interdigitated structure, which can shorten the ion migration distance, shorten the charging time of the battery, and improve The power density of the battery; (5) Using graphene or carbon nanotubes as the negative electrode material can greatly increase the body surface area of the negative electrode, reduce the charge transfer resistance, and increase the ion migration number.

Description of drawings

1A-1D are schematic diagrams of housing cross-sections of each step of manufacturing a half-side battery housing in the MEMS lithium battery manufacturing method of the present invention;

Fig. 2 is the three-dimensional schematic view of the battery casing including the positive electrode after the MEMS lithium battery of the present invention is completed;

Fig. 3 is the three-dimensional schematic view of the battery casing including the negative electrode after the MEMS lithium battery of the present invention is completed;

Fig. 4 is the three-dimensional schematic diagram of the MEMS lithium battery of the present invention encapsulating two battery casings together;

Fig. 5 is a schematic diagram of the porous and loose structure on the three-dimensional column array of the MEMS lithium battery of the present invention;

6 is a top view of a three-dimensional column array (11-positive column, 12-negative column) of the MEMS lithium battery of the present invention;

Fig. 7 is a longitudinal sectional schematic view of the battery electrode and the separation wall (13) of the MEMS lithium battery of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The basic design idea of the present invention is to use MEMS technology to process three-dimensional column arrays and pools with regular distribution on two substrates. The column arrays on these two different substrates are used as three-dimensional positive and negative supports respectively. , and then modify and fix different nanomaterials on the array column to form positive and negative electrodes, then align and seal the two, and finally inject the electrolyte material through the injection hole, and seal the injection hole after filling to form a battery. Further preferably, the post arrays in dislocation distribution can form an interdigitated structure, and the intersecting depth of the interdigitated structures is determined and adjusted by the height of the bosses formed in the manufacturing process.

More specifically, the MEMS lithium battery of the present invention includes:

The first casing is made of a semiconductor material, on which a cavity is formed and the positive electrode of the battery is integrally formed in the cavity; the semiconductor material can be silicon-based, glass, carbon-based, gallium arsenide and other materials , wherein silicon-based materials are preferred.

The second shell is made of the same semiconductor material as the first shell, and a cavity is formed on it that is connected to the first shell, and the negative electrode of the battery is integrally formed in the cavity;

The electrolyte is housed in the cavity between the first case and the second case.

In the present invention, the positive electrode, for example, can be selected from the following materials:

(1) LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , etc.;

(2) Ternary composite materials: such as Li[Ni _1/3 Co _1/3 Mn _1/3 ]O ₂ , LiNi _1-x Mn _x O ₂ , LiNi _1-x Co _x O ₂ , LiNi _{1-x- y} Co _x Mn _y O ₂ etc., wherein x and y are real numbers, 0<x<1, 0<y<1.

(3) LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , etc. are modified by means of doping and coating to form new positive electrode materials, such as LiFePO ₄ /C, LiCoO ₂ /C, LiNi _1-x Co _x O ₂ and other composite materials. Wherein, doping elements include, for example, Mg, Ni, Mn, Zr, Ti, V, Mo, Ga, and the like. The coated material includes, for example, C, CuO, Al ₂ O ₃ , ZrO ₂ , Co ₃ O ₄ , Li ₄ Ti ₅ O ₁₂ , LaF ₃ , AlF ₃ and the like.

Among them, Li[Ni _1/3 Co _1/3 Mn _1/3 ]O ₂ is preferably used as the positive electrode material.

In the present invention, for example, the negative electrode can be selected from the following materials:

(1) Graphite;

(2) Using graphene as the starting material to synthesize new composite materials, such as the composite of metal or metal oxide and graphene, the introduced substances include Si, Ge, Sb, Sn, Pt, and Fe ₃ O ₄ , NiO, Co ₃ O ₄ , SnO ₂ , etc. Metal oxides include, for example, SnO, SnO ₂ , WO ₂ , MoO ₂ , VO ₂ , TiO ₂ , LixFe ₂ O ₃ , Li ₄ Mn ₂ O ₁₂ , Li ₄ Ti ₅ O ₁₂ and the like.

Among them, the composite material of _SnO2 and graphene is preferably used as the negative electrode material.

The electrode material and shape of the positive and negative electrodes can be selected according to the type and application of the battery. The shape of the positive and negative electrodes can be, for example, a film, a cylinder, or a three-dimensional column array. As a preferred embodiment, both adopt a three-dimensional column array structure, and the column array is used as a support, and different nanomaterials are respectively modified and fixed on the surface to form the positive electrode and the negative electrode.

The surface of the negative electrode and the positive electrode is conductive after being modified with nano-materials, so it can be drawn out to the outer terminal through the metal electrode or conductive coating on the surface, thereby forming the positive and negative electrodes of the battery to transmit power to the outside.

In the present invention, the positive and negative electrodes preferably use a three-dimensional column array as a carrier, and the shape of each column in the three-dimensional column array can be a cylinder, a cone, a circular frustum, a bottle shape, a regular hexagonal prism, other polyhedral prisms, Y-shaped prisms, etc. , preferably using a cylinder and a Y-shaped prism structure. The cross-sectional shape of each unit column can be circular, Y-shaped, rectangular, square, star-shaped or other shapes. There is no special limitation on the cross-sectional shape, as long as it is beneficial to increase the surface area of the column. The surface of each column in the three-dimensional column array is modified with different nanomaterials. For example, when used as a lithium battery, the nanomaterial modified by the positive electrode can be a single nanomaterial or a composite nanomaterial, such as Ni/NiO composite nanofoam, Ni/Sn alloy nanowires, Au/Sn nanofilms, etc., the nanomaterials modified by the negative electrode can be single nanomaterials or composite nanomaterials, such as graphene, carbon nanotubes, etc.; when used as a nickel-hydrogen battery, the positive electrode Ni(OH) ₂ is used, and carbon black, CoSi, hydrogen storage alloy, etc. are used for the negative electrode.

The column array can be arranged regularly or irregularly in the cavity between the first casing and the second casing. As a preferred embodiment, the positive pole and the negative pole form two staggered matrices respectively, as In a more preferred embodiment, the positive and negative column arrays can form an interdigitated structure. The so-called interdigitated structure means that the column arrays of the positive electrode of the battery and the column arrays of the negative electrode are arranged in a dislocation and cross arrangement, so that the ion migration distance can be greatly shortened, and the charging of the battery can be shortened. time, and can increase the power density of the battery.

As a preferred embodiment, the three-dimensional column array in the present invention adopts the Y-shaped prism array as shown in Figure 6, which has the following advantages in addition to the advantages of other column array structures: this "trap" type network The surface area is larger, and more nanomaterials can be modified and fixed, which can greatly increase the number of mobile ions and increase the power density; the modification and fixation of nanomaterials in this "trap" structure is more stable, and it is not easy to be damaged by vibration. Cross-mixing of the nanomaterials causing the anode and cathode.

In the present invention, the electrolyte, for example, adopts a non-aqueous electrolyte, preferably a non-aqueous organic electrolyte, such as a non-aqueous organic electrolyte made by dissolving a lithium salt in an organic solvent as a solute, and a further preferred electrolyte is: LiPF ₆ dissolved in ethylene carbonate , dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate prepared in a certain proportion of the electrolyte prepared in the quaternary solvent. In addition, the electrolyte can also be in the form of colloid, so that the prepared battery is a colloidal battery, and the storage performance and service life are more excellent.

In a preferred embodiment, as shown in FIG. 7 , a separation wall (equivalent to the diaphragm of a traditional battery) can also be provided between the positive and negative electrodes, which is used to allow ions to pass through and prevent the short circuit between the positive and negative electrodes. The material of the separation wall is the same as that of the base, and is prepared by deep etching or chemical etching.

In a preferred embodiment, a conductive coating can also be provided on the positive electrode current collector, such as an aluminum foil coating, so as to effectively improve the adhesion of the positive electrode sheet, reduce the amount of binder used, and significantly improve the battery capacity. performance.

For the seal between the first casing and the second casing, that is, the sealing of the entire battery, bonding seals, BCB seals, or other adhesive seals may be used. There is no limitation on the sealing process, as long as the firmness and sealing of the entire battery can be ensured.

The size of the battery prepared above is very small. Since it is prepared by the MEMS process, it can be mounted on electronic circuits such as circuit boards like patch components to provide power to corresponding components.

Because the size of the batteries prepared above is very small, the output voltage and capacity of the batteries are relatively small, so the battery array can be arranged in a grid to form a battery pack to jointly supply power to the outside, so as to improve the power supply voltage and battery capacity. capacity.

The invention also discloses a method for preparing a chip battery, comprising the following steps:

Use semiconductor material as the substrate, evaporate a layer of Au/Cr by sputtering or electron beam, Au thickness is 100-500nm, preferably 200nm, Cr thickness is 10-50nm, preferably 20nm, use dry film (negative resist) as photoresist Perform photolithography, and then chemically etch to remove Au/Cr in other parts to form lead-out electrodes;

Deposit a layer of metal on the upper surface of the substrate, such as Au, Al, preferably aluminum, and then fix a layer of dry film on the upper surface of the substrate as a photoresist for photolithography to form a micro-column array pattern, and remove the column array by chemical etching Metals other than metals are then etched using a deep etching process to form a microcolumn array and the pool body of the battery's first housing;

Modifying and immobilizing nanomaterials on the surface of the microcolumn array as the positive electrode;

Using the same method, the second shell body of the negative electrode and its lead-out electrode are prepared, and nanometer materials are modified on the surface of the micro column array as the negative electrode.

After the nano-materials are respectively modified and fixed on the two pool bodies and the column array, and the positive and negative electrodes are formed, a layer of insulating and corrosion-resistant glue, such as BCB adhesive or other, is coated on the sealing surfaces of the first shell and the second shell Type of adhesive, and then the first case and the second case are aligned and contacted, and the packaging of the battery is completed after the adhesive solidifies, forming the case of the battery.

The electrolyte is injected from the reserved sample injection hole, and after the electrolyte is filled with the cell body, the sample injection hole can be sealed to obtain a MEMS battery.

Wherein, before forming the extraction electrodes, a protrusion may also be formed on the upper surface of the substrate by a deep etching or chemical etching process, so that during the subsequent etching process, the protrusion is used to form an interdigitated structure.

In order to maximize the body surface area of the support structure, the present invention discloses a method of electrochemically corroding the surface of the column array. As shown in Figure 5, a layer of porous and loose structure is formed on the three-dimensional column array, that is, on the column array A layer of porous silicon layer is formed on the surface, and the pore size, porosity and thickness of the porous silicon layer can be adjusted by electrochemical corrosion conditions (such as the ratio of each component in the corrosion solution, corrosion time, external loading current and other factors). After growing the porous silicon layer on the surface of the column, its surface area can be increased by 1-3 orders of magnitude, which can greatly increase the modified and fixed nano-electrode material, increase the number of ion migration, and increase the energy density and power density of the battery.

More specifically, as a preferred embodiment, the present invention discloses a method for further modifying the electrode surface of a silicon-based substrate to form a loose porous structure, including the following steps:

(1) Preparation of etching solution, HF: H ₂ O ₂ : Ethanol: H ₂ O = 11: 1: 4: 12, wherein the function of ethanol is to eliminate the air bubbles on the silicon surface, so that the porosity and pore size of the porous layer are basically the same; HF and H ₂ O ₂ are mainly used to corrode semiconductor materials such as silicon base;

(2) make electrode, take silicon chip as substrate, sputter a layer of metal on its surface, as Au, Pt, preferably Pt;

(3) Place the Pt electrode and the silicon-based substrate of the porous silicon layer to be prepared (the substrate where the positive electrode and the negative electrode are located) face to face and vertically place them in the etching solution, and connect them to an external power supply;

(4) Turn on the power supply, pass a current of 20-150mA/cm ² , preferably 80mA/cm ² , corrode for 20-60 minutes, and the corrosion rate is 0.8 microns/min. After 20 minutes of corrosion, the surface of the pool body and the column can be A porous layer is formed.

The thickness of the porous silicon can be selected between 1-50 microns, and in the embodiment of the present invention, the thickness of the porous silicon is preferably 15 microns.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments of silicon-based substrates.

As shown in FIG. 1A , it is a selected silicon substrate 1 .

As shown in FIG. 1B, in order to form an interdigitated structure, a boss is formed on the upper surface of the silicon substrate 1 by deep etching or chemical etching;

Evaporate a layer of Au/Cr by sputtering or electron beam, the thickness of Au is 200nm, and the thickness of Cr is 20nm. Use dry film (negative resist) as photoresist for photolithography, and then chemically etch to remove Au/Cr in other parts. forming an extraction electrode as shown in FIG. 1C;

Deposit a layer of metal aluminum on the boss surface, and then fix a layer of dry film on the boss surface as photoresist for photolithography to form a column array pattern, use chemical etching to remove Al outside the column array, and then use deep etching process Etching to form a micro-column array and a battery cell body as shown in Figure 1D (indicated by dotted lines in the figure);

Modify and fix the nanomaterial Ni/NiO composite nanofoam on the surface of the microcolumn array as the positive electrode, as shown in Figure 2;

Using the same method, the cell body of the negative electrode and its lead-out electrode were prepared, and graphene was modified on the surface of the micro-column array as the negative electrode, as shown in FIG. 3 .

After the cell body and column array on the two silicon bases are respectively modified and fixed to form the positive and negative electrodes, a layer of BCB glue is coated on the sealing surface of the two silicon bases, and then the silicon base where the positive electrode is located and the silicon base where the negative electrode is located. The substrates are aligned and contacted, as shown in Figure 4, after the BCB glue is solidified, the packaging of the battery is completed to form the shell of the battery.

The electrolyte is injected from the sample injection hole, and after the electrolyte is filled with the cell body, the sample injection hole can be sealed to obtain a MEMS lithium battery.

It can be seen through theoretical calculation that the theoretically estimated battery power density of the MEMS lithium battery of the present invention is ≥5mWcm ^-2 μm ^-1 , and the working temperature can be between -50°C and 70°C. Through actual trials in small batches, the MEMS lithium battery of the present invention has also achieved satisfactory technical effects.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (8)

1. a kind of preparation method of MEMS lithium batteries, comprises the following steps：

With the substrate that semi-conducting material is the first housing, the first extraction electrode, the first three-dimensional are formed by MEMS technology thereon Column array and the first pond body, wherein the described first three-dimensional column array is located in first pond body；Wherein, it is described in substrate In the step of the first extraction electrode of upper formation, including the step of form Au/Cr metal levels on the substrate as mask, wherein The Au thickness degree is 100~500nm, and Cr thickness degree is 10~50nm；

The first nano material is fixed as positive pole in the described first three-dimensional column array surface modification；

Using same method, the second housing comprising negative pole is prepared by MEMS technology, formed on second housing Second extraction electrode, the second three-dimensional column array and the second pond body, and fixed in the described second three-dimensional column array surface modification Second nano material is used as negative pole, wherein the described second three-dimensional column array is located in second pond body, and second pond Body is aligned to form an accommodating cavity with first pond body, the first three-dimensional column array and the second three-dimensional column battle array Row offset one from another；Wherein, it is described the step of the second extraction electrode is formed in substrate in, including form Au/ on the substrate The step of Cr metal levels are as mask, wherein the Au thickness degree is 100~500nm, Cr thickness degree is 10~50nm；

First housing and the second housing are aligned and encapsulated, the housing of the MEMS lithium batteries is formed；

Wherein, before first extraction electrode and/or the second extraction electrode is formed, by deep etching or chemical etching technology First boss and/or second boss are formed on the upper surface of substrate of first housing and/or the second housing, so that behind Etching process procedure in, form interdigital structure using the first boss and second boss.

2. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein described by first housing and second shell After the step of body is aligned and encapsulates, also including injecting electrolyte from reserved note sample hole, matter to be electrolysed is full of sealing after pond body Note sample hole, the step of so as to obtain the MEMS lithium batteries.

3. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein being repaiied in the described second three-dimensional column array surface After the step of decorations fix the second nano material as negative pole, the step of first housing and the second housing are aligned and are encapsulated Before, it is additionally included in the step of filling colloidal electrolyte in the pond body on first housing and the second housing.

4. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein by deep etching or chemical etching technology in institute State and the first/second pond body and the reserved column in the first/second pond body are formed on first/second housing, lead to Cross photoetching process and the first/second three-dimensional column array is formed on the reserved column.

5. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein the semi-conducting material is silicon substrate, carbon-based or arsenic Change gallium material.

6. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein the Au thickness degree is 200nm, Cr thickness degree It is 20nm.

7. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein first housing comprising positive pole and comprising The preparation of the second housing of negative pole in no particular order order.

8. the preparation method of MEMS lithium batteries as claimed in claim 1, wherein described encapsulate the first housing and the second housing The step of in, using bonded seal or BCB sealing technologies.