Three-dimensional porous current collector with gradient pore structure and preparation method and application thereof
阅读说明：本技术 具有梯度孔结构的三维多孔集流体及其制备方法和应用 (Three-dimensional porous current collector with gradient pore structure and preparation method and application thereof ) 是由 陈立宝 杨昊 陈月皎 梅琳 于 2021-04-30 设计创作，主要内容包括：本发明属于负极材料领域,具体公开了具有梯度孔结构的三维多孔集流体及其制备方法和应用；所述的方法为：在模具中按任意顺序铺设原料粉末A和原料粉末B,随后进行常压松装烧结,即得；所述的原料粉末A、原料粉末B为水雾化法或电解法制得的金属原料粉末,且二者的D50半径不相同。此外,本发明还提供了所述的制备方法制得的集流体及其在金属电池中的应用。本发明研究发现,通过所述的原料粉末A、原料粉末B形态、级配结构、层级铺料方式和烧结方式的联合控制,能够获得具有层级孔结构的全新集流体；更重要的是,所构建得到的特殊集流体能够有效改善金属均匀沉积,从而有助于改善金属电池电化学性能特别是长期循环稳定性。(The invention belongs to the field of negative electrode materials, and particularly discloses a three-dimensional porous current collector with a gradient pore structure, and a preparation method and application thereof; the method comprises the following steps: paving the raw material powder A and the raw material powder B in a die in any order, and then sintering under normal pressure in a loose manner to obtain the powder A; the raw material powder A and the raw material powder B are metal raw material powder prepared by a water atomization method or an electrolysis method, and the radii of D50 of the raw material powder A and the raw material powder B are different. In addition, the invention also provides the current collector prepared by the preparation method and application thereof in metal batteries. Research of the invention finds that a brand new current collector with a hierarchical pore structure can be obtained through the combined control of the shapes, the grading structures, the hierarchical paving mode and the sintering mode of the raw material powder A and the raw material powder B; more importantly, the special current collector constructed can effectively improve the uniform deposition of metal, thereby being beneficial to improving the electrochemical performance of the metal battery, particularly the long-term cycling stability.)
1. A preparation method of a three-dimensional porous current collector with a gradient pore structure; the method is characterized in that: in a mould, firstly paving raw material powder A in the mould to form a raw material powder A layer, and then paving raw material powder B on the surface of the raw material powder A layer to form a raw material powder B layer; or paving the raw material powder B in the die to form a raw material powder B layer, and then paving the raw material powder A on the surface of the raw material powder B layer to form a raw material powder A layer;
after laying, carrying out normal-pressure loose-loading sintering to obtain the finished product;
the raw material powder A and the raw material powder B are metal raw material powder prepared by a water atomization method or an electrolysis method, and the radii of D50 of the raw material powder A and the raw material powder B are different.
2. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 1; the method is characterized in that: the metal raw material powder has irregular morphology.
3. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 1; the method is characterized in that: the raw material powder A and the raw material powder B are the same or different in components;
the metal raw material powder is metal simple substance powder and alloy powder thereof.
4. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 1; the method is characterized in that: the particle size of the raw material powder A is 100-300 meshes;
the particle size of the raw material powder B is 500-1000 meshes.
5. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 4; the method is characterized in that: the ratio of the paving thickness of the raw material powder A to the paving thickness of the raw material powder B is 1-4: 1.
6. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 1; the method is characterized in that: the sintering mode is one of conventional high-temperature sintering, laser sintering and spark plasma sintering.
7. The method for preparing a three-dimensional porous current collector having a gradient pore structure according to claim 1; the method is characterized in that: the sintering process is carried out in a protective atmosphere;
the loose sintering process is two-stage gradient sintering, wherein the temperature of the first stage is 550-700 ℃;
the temperature of the second section is 750-900 ℃.
8. A three-dimensional porous current collector with a gradient pore structure prepared by the preparation method of any one of claims 1 to 7;
raw material powder A and raw material powder B are mutually metallurgically fused, a sintering phase is formed among powder particles, and a gradient hierarchical pore structure is formed by particle gaps;
the porosity is 50-70%, the average pore diameter is 20-100 mu m, and the pore volume under unit mass is 0.05 cm3 g-1~0.3 cm3 g-1。
9. Use of the three-dimensional porous current collector with a gradient pore structure prepared by the preparation method of any one of claims 1 to 7 for preparing a metal battery.
10. A metal battery, characterized by comprising a three-dimensional porous current collector with a gradient pore structure prepared by the preparation method of any one of claims 1 to 7;
the active metal in the metal battery is at least one of lithium, sodium, zinc and magnesium metal.
Technical Field
The invention belongs to the technical field of metal batteries, and particularly relates to a three-dimensional porous current collector with a gradient pore structure for a metal battery, and a preparation method and application thereof.
Background
With the rapid development of high-end electronic products such as mobile phones and electric vehicles, the demand of people for energy storage devices is increasing. Meanwhile, the existing commercial lithium ion battery is limited by lower theoretical capacity and is difficult to realize wider application. The metal battery is a secondary battery using metals such as lithium, sodium, zinc, magnesium and the like as a negative electrode, has high theoretical specific capacity and safety, and is hopefully applied to next-generation high-specific-energy battery materials. Taking a lithium metal battery as an example, lithium attracts a wide attention of scholars due to the lowest standard electrode potential (-3.04V vs standard hydrogen electrode) and the extremely high specific mass capacity (3860 mA h g-1). However, lithium metal anodes tend to be accompanied by large volume changes during cycling with uncontrolled lithium dendrite growth. Similar dendrite growth processes also occur in zinc, sodium, etc. metal batteries.
The use of three-dimensional porous current collectors for metal anodes is believed to be the most effective means of simultaneously inhibiting dendrite growth and mitigating volume expansion, with the porous structure being able to reduce local current density while providing a deposition host for the active metal. However, the three-dimensional porous current collectors commonly used at the present stage are mainly foam metal current collectors, 3D porous carbon current collectors, and the like, and the uniformity of the pore structures of these materials is not ideal, and the pore structures are complex, and the polarization is not uniform at the active metal deposition stage, which easily causes the non-uniform deposition of metals, thereby causing the premature attenuation of the capacity of the three-dimensional current collector, and the electrochemical performance is not ideal.
Disclosure of Invention
In order to solve the problems of poor deposition uniformity of active metal and unsatisfactory electrochemical performance of the existing current collector, the first objective of the invention is to provide a preparation method of a three-dimensional porous current collector with a gradient pore structure, aiming at preparing the three-dimensional porous current collector with the gradient hierarchical pore structure and excellent electrochemical performance.
The second purpose of the invention is to provide the three-dimensional porous current collector with the gradient pore structure prepared by the preparation method.
The third purpose of the invention is to provide the application of the three-dimensional porous current collector with the gradient pore structure in a metal battery.
A preparation method of a three-dimensional porous current collector with a gradient pore structure comprises the steps of laying raw material powder A and raw material powder B layer by layer in a mould according to any sequence, and then carrying out normal-pressure loose-packing sintering to obtain the three-dimensional porous current collector;
the raw material powder A and the raw material powder B are metal raw material powder prepared by a water atomization method or an electrolysis method, and the radii of D50 of the raw material powder A and the raw material powder B are different.
Research of the invention finds that a brand new current collector with a hierarchical pore structure can be obtained through the combined control of the shapes, the grading structures, the hierarchical paving mode and the sintering mode of the raw material powder A and the raw material powder B; more importantly, the special current collector constructed can effectively improve the uniform deposition of metal, thereby being beneficial to improving the electrochemical performance of the metal battery, particularly the long-term cycling stability.
In the present invention, the metal raw material powder is required to be a raw material powder formed by a water atomization method or an electrolysis method. In the invention, the metal raw material powder has irregular appearance.
In the present invention, the raw material powder a and the raw material powder B required in the present invention can be prepared by a water atomization method or an electrolysis method which are well known in the industry.
In the invention, the water atomization method is a powder preparation method which directly crushes liquid metal or alloy into fine liquid drops by means of the impact action of high-pressure water flow and quickly condenses, and is suitable for preparing irregular powder or spheroidal powder; the electrolysis method is a powder preparation method for depositing and separating out metal powder at a cathode by electrolyzing molten salt or aqueous solution of salt, and is suitable for preparing high-purity irregular powder.
In the present invention, the raw material powder a and the raw material powder B are the same or different in composition; preferably the same;
preferably, the metal raw material powder is elemental metal powder and alloy powder thereof;
more preferably, the element in the metal raw material powder is at least one of copper, nickel and zinc;
more preferably, the metal raw material powder is copper-zinc alloy powder.
In the present invention, the material laying order of the raw material powder a and the raw material powder B is not particularly required. For example, the raw material powder a may be first laid in a mold to form a raw material powder a layer, and then the raw material powder B may be laid on the surface of the raw material powder a layer to form a raw material powder B layer. Alternatively, the raw material powder B may be first laid in a mold to form a raw material powder B layer, and then the raw material powder a may be laid on the surface of the raw material powder B layer to form a raw material powder a layer.
In the invention, the radius of D50 of the raw material powder A and the raw material powder B is different, so that gradient hierarchical pores are constructed between particles. According to the invention, through the combined control of the material paving mode and the grading mode, the loose loading and 0 external pressure sintering process are further matched, so that the material with excellent metal deposition uniformity and excellent cycling stability in the field of metal batteries can be prepared.
Preferably, the particle size of the raw material powder A is 100-300 meshes; further preferably 200-300 meshes; more preferably 200 to 250 mesh. The particle size of the raw material powder B is 500-1000 meshes; further preferably 500 to 600 meshes; more preferably 500 to 550 mesh.
In the present invention, the mold may be a mold known in the industry, and may be, for example, a high-purity graphite mold or a corundum mold; the inner diameter is, for example, 4 mm to 20 mm.
Preferably, the ratio of the paving thickness of the raw material powder A to the paving thickness of the raw material powder B is 1-4: 1; more preferably 1.5 to 2: 1.
Further preferably, the paving thickness of the raw material powder A is 0.2-0.6 mm; further preferably 0.3 to 0.4;
more preferably, the paving thickness of the raw material powder B is 0.1-0.2 mm.
In the invention, after the material is paved, the material layer is strickled off, and then the normal pressure sintering treatment is carried out.
The loose sintering process is two-stage gradient sintering, wherein the temperature of the first stage is 550-700 ℃; more preferably 600 to 650 ℃. The temperature rise rate of the first stage is preferably 4-10 ℃/min.
The temperature of the second section is 750-900 ℃; further preferably 800 to 850 ℃. The temperature rise rate of the second stage is preferably 1-3 ℃/min.
The first period of heat preservation time is 0.5-1.5 h; more preferably 1 to 1.5 hours.
The heat preservation time of the second section is 2-5 h; more preferably 3 to 4 hours.
The sintering process is carried out in a protective atmosphere and is maintained at normal pressure.
In the invention, the adopted sintering mode is conventional high-temperature sintering, laser sintering or spark plasma sintering; the preferred mode is conventional high temperature sintering.
In the invention, the sintered blank is cooled, then is put into an organic solvent for ultrasonic cleaning, and is further dried to obtain the material;
the organic solvent is at least one of absolute ethyl alcohol, acetone and other organic solvents;
in the third step, the drying condition is vacuum drying, and the temperature is 50-80 ℃.
The preferred preparation method of the invention; the method comprises the following steps:
step one
Uniformly spreading a small amount of fine powder (particle B) into a mold, leveling the surface of the powder by using a glass plate or a silica gel plate, spreading a layer of coarse powder (particle A) on the surface of the powder, leveling the surface, and simultaneously applying no pressure in the direction vertical to the powder body.
Step two
And (3) placing the die paved with the powder obtained in the step one into a furnace, and controlling a sintering process to sinter, so that powder particles are connected with each other to form a whole, and gaps among the particles form pores.
Step three
And D, taking out the sintered blank obtained in the step two, putting the sintered blank into an organic solvent for ultrasonic cleaning, and further drying to obtain the three-dimensional porous current collector with the gradient pore structure for the metal battery.
Preferably, the specification of the metal or alloy powder in the first step is as follows: the particle size of the coarse powder is 100-300 meshes, preferably 300-350 meshes; the fine powder has a particle size of 500-600 meshes, preferably 500-550 meshes; the powder preparation method is a water atomization method.
Preferably, in the second step, the sintering process comprises: in order to avoid volatilization of powder components in the high-temperature sintering process and ensure the stability of the powder components, gradient temperature rise is adopted for sintering: wherein the temperature of the first section is 600 ℃; the temperature of the second section is 850 ℃; the heat preservation time of the first section is 0.5 h; the heat preservation time of the second section is 4 h. The atmosphere was argon at normal pressure.
Preferably, in the third step, the organic solvent is at least one selected from organic solvents such as absolute ethyl alcohol and acetone, and is preferably absolute ethyl alcohol; in the third step, the drying condition is vacuum drying, the temperature is 50-80 ℃, and preferably 60 ℃.
The invention also comprises the three-dimensional porous current collector with the gradient pore structure prepared by the preparation method;
preferably, raw material powder A and raw material powder B are metallurgically fused with each other (interfacial fusion), a sintering phase is formed between powder particles, and a gradient hierarchical pore structure is formed by particle gaps.
The particles A and B are metal raw material powder prepared by a water atomization method or an electrolysis method, and are further matched with the construction of the hierarchical structure, so that metallurgical bonding among the particles can be realized, and pores constructed among the particles are in a large-pore-small-pore hierarchical structure. The structure of the invention can effectively solve the problem of uneven polarization of deposition, can effectively contain metal and can promote the uniform deposition of the metal. The material of the present invention can exhibit excellent cycle stability.
Preferably, the porosity is 50-70%, the average pore diameter is 20-100 μm, and the pore volume under unit mass is 0.05 cm3 g-1-0.3 cm3 g-1.
The invention also discloses application of the three-dimensional porous current collector with the gradient pore structure, and the three-dimensional porous current collector is used for preparing a metal battery.
The research of the invention finds that the current collector constructed by the special method can effectively improve the deposition uniformity of metal and is beneficial to improving the cycle stability of a metal battery.
Preferably, the application is used for preparing a negative electrode of a metal battery;
further preferably, the application is that the metal battery negative electrode is prepared by taking the metal battery negative electrode as a current collector and filling active metal into the current collector;
preferably, the application adopts a melting method or an electrodeposition method to fill active metal into a current collector;
preferably, in the application, the active metal in the metal battery is at least one of lithium, sodium, zinc and magnesium metal. That is, the negative electrode of the metal battery is a battery including metal lithium, metal sodium, metal zinc, and metal magnesium.
In the assembled battery according to the present invention, the large pore surface (sintered surface of metal powder a) of the current collector is preferably assembled to face the separator.
According to the application, after the three-dimensional porous current collector with the gradient pore structure for the metal battery is compounded with lithium metal, the symmetrical battery is prepared, and the test circulation stability is high, and the battery can stably circulate for 1500-2000 hours under the current density of 1 mA cm & lt-2 & gt.
According to the application, the metal battery is used for testing the coulombic efficiency of zinc metal dissolution/deposition by using a half-battery prepared from the three-dimensional porous current collector with the gradient pore structure and the zinc sheet, and the coulombic efficiency can reach 95% under the current density of 1 mA cm & lt-2 & gt.
According to the application, after the three-dimensional porous current collector with the gradient pore structure for the metal battery is compounded with lithium metal, the metal battery and lithium iron phosphate are prepared into a full battery, the cycling stability under the condition of 0.5C is tested, and the capacity retention rate of 200 cycles is more than 87%.
The invention also provides a metal battery, which comprises the three-dimensional porous current collector with the gradient pore structure;
the active metal in the metal battery is at least one of lithium, sodium, zinc and magnesium metal. For example, the metal battery is a lithium metal battery, a sodium metal battery, a zinc metal battery, or a magnesium metal battery.
The invention designs a three-dimensional porous current collector with a gradient pore structure for a metal battery; the raw material powder is irregular water atomized powder or electrolytic powder, and the components can be copper, nickel, copper-zinc alloy and the like; the metal battery is a lithium, sodium, zinc, magnesium metal battery and the like; the main component of the three-dimensional porous current collector with the gradient pore structure for the metal battery is copper-zinc alloy; the current collector has a large-pore-small pore gradient three-dimensional pore structure.
The invention designs a gradient pore structure, simultaneously has macropores and micropores and presents gradient distribution, and can realize the deposition of active metal from the micropores to the macropores when being used as a current collector of a metal battery, thereby realizing the high-efficiency utilization of the pore structure. Meanwhile, sintering the powder under normal pressure by using a loose sintering method to prepare the three-dimensional porous current collector with the gradient pore structure. The obtained three-dimensional porous current collector with the gradient pore structure is applied to a metal battery cathode, can inhibit dendritic crystal growth and relieve volume expansion at the same time, and has excellent long-acting cycle stability. The preparation method is simple and feasible and is suitable for industrialization. Meanwhile, after optimization, the three-dimensional porous current collector is applied to the lithium metal battery cathode through the synergistic effect with the preparation process, taking the lithium metal battery as an example, stable circulation for 1500-2000 h under the current density of 1 mA cm & lt-2 & gt is realized, and the material is far higher than that of the existing lithium metal battery cathode material.
Drawings
FIGS. 1, 2 and 3 show SEM pictures of the powder obtained by the water atomization method, the powder obtained by the electrolysis method and the powder obtained by the gas atomization method (used in comparative example), respectively.
Fig. 4, 5, and 6 are scanning electron micrographs (wherein fig. 4a is an upper surface SEM image, fig. 4b is a lower surface SEM image, and fig. 4c is a cross-sectional SEM image) of the upper and lower surfaces and cross-section, respectively, of the three-dimensional porous copper zinc current collector of example 1, and voltage-time curves for coulombic efficiency testing and symmetrical cell long cycle for lithium metal cells.
Figure 7 is a coulombic efficiency test of the copper zinc current collector of example 2 used as the negative electrode of a zinc metal battery.
Fig. 8 and 9 are the voltage-time curves of the copper current collector of example 3 for the coulombic efficiency test and the long cycle of the symmetric cell, respectively.
Fig. 10 and 11 are the voltage-time curves of the copper-zinc current collector of example 4 for the coulombic efficiency test and the long cycle of the symmetric cell, respectively.
Fig. 12, 13, 14 are SEM photographs of the surface of the fine pores of the copper zinc current collector of example 5, the coulombic efficiency test for a lithium metal battery, and the voltage-time curves for a long cycle of a symmetric battery, respectively.
Fig. 15 and 16 are the coulombic efficiency test and the voltage-time curve of the symmetrical cell for long cycle of the copper/copper-zinc composite current collector of example 6 for a lithium metal battery, respectively.
Fig. 17 and fig. 18 are voltage-time curves of the copper-zinc current collector of comparative example 1 for coulombic efficiency testing and long cycling of a symmetric cell, respectively.
Fig. 19 and fig. 20 are voltage-time curves of the copper-zinc current collector of comparative example 2 for coulombic efficiency testing and long cycling of a symmetric cell, respectively.
Fig. 21 and 22 are SEM photographs of the surface morphology of the copper current collector of comparative example 3 and coulombic efficiency tests for a lithium metal battery, respectively.
Detailed Description
The invention uses loose sintering method to prepare three-dimensional porous current collector with gradient pore structure for metal battery, and realizes large pore-small pore gradient three-dimensional pore structure by spreading powder and controlling sintering process, so as to achieve the optimal performance of current collector. The following is a further description of the embodiments.
The metal powder and alloy powder used in the examples and comparative examples of the present invention were purchased from Shanghai Chilean industries, Ltd, and the preparation methods included water atomization, electrolysis and gas atomization (for comparative examples). Wherein SEM pictures of the powder prepared by water atomization, electrolytic method and gas atomization are shown in figures 1, 2 and 3 respectively.
The sintering process of the present invention is performed under argon atmosphere, and the pressure during the reaction is maintained at normal pressure during the sintering process (for example, by introducing argon and appropriately decompressing the reaction system under 0 external pressure (i.e. normal pressure)).
Example 1:
first, 500 mesh copper-zinc alloy powder (powder B) was uniformly spread in a high purity graphite mold having an inner diameter of 14 mm at a powder spreading height of 0.2 mm, and then the surface of the powder was scraped off with a glass plate. And then a layer of copper-zinc alloy powder (powder A) of 200 meshes is paved on the surface of the powder, the paving height is 0.3 mm, the surface is strickleed by a glass plate, and the total height of the strickled powder is 0.5 mm. Then adopting a conventional high-temperature sintering method: placing the mould paved with the powder into a sintering furnace, wherein the atmosphere is argon normal pressure, and adopting gradient temperature rise: heating to 600 ℃ at the speed of 5 ℃/min and preserving heat for 1 h; then heating to 800 ℃ at the speed of 2 ℃/min and preserving heat for 3 h; and then naturally cooling. And taking out the mold after cooling and disassembling the mold. And obtaining the three-dimensional porous copper-zinc alloy wafer with the gradient pore structure.
And then putting the porous copper-zinc alloy wafer into absolute ethyl alcohol, moving the wafer into an ultrasonic machine for ultrasonic treatment for 10 min, and removing residual powder and impurities on the surface. And taking out the wafer subjected to the ultrasonic treatment, putting the wafer into a vacuum oven, and drying the wafer at the temperature of 60 ℃. And the porous current collector can be further used as a three-dimensional porous current collector of a metal battery.
The obtained three-dimensional porous current collector is used for a lithium metal battery cathode, a battery is assembled by taking a mode that a large pore surface (particle A sintering surface) faces a diaphragm (the side close to the diaphragm) and a small pore surface is far away from the diaphragm as an anode and a lithium sheet as a cathode, 1M LiTFSI/DOL (volume ratio 1: 1) and 1% lithium nitrate are taken as electrolyte, the battery is charged to 1V after discharging for 1 h under the current density of 1 mA cm < -2 > from the voltage of 1V, the ratio of the charging electric quantity to the discharging electric quantity is calculated to represent the coulombic efficiency of the current collector, and the coulombic efficiency can reach 98% and stably circulate for 150 circles; or discharging for 20 h under the current density of 0.2 mA cm < -2 > to realize the compounding of the three-dimensional porous current collector and lithium into a symmetrical battery, continuously charging and discharging for 1 h under the current density of 1 mA cm < -2 >, testing the cycling stability, and keeping the stable cycling time for 1600 h.
Example 2:
the obtained three-dimensional porous current collector is prepared by the same method as that in the example 1, is used for a zinc metal battery cathode (the large pore side is close to a diaphragm), is used as a positive electrode, is assembled into a battery by using a 2M ZnSO4 solution as an electrolyte, is charged to 1V after being discharged for 1 h under the current density of 1 mA cm < -2 > from the voltage of 1V, and is used for representing the coulombic efficiency of the current collector by calculating the ratio of the charging electric quantity to the discharging electric quantity, wherein the coulombic efficiency can reach 97 percent and stably circulates for 90 circles.
Example 3:
compared with example 1, the difference is only that powder B is pure copper powder with 500 meshes; powder a was 200 mesh pure copper powder, and the other conditions were the same as in example 1.
Example 4:
compared with example 1, the difference is only that the powder B is 600-mesh copper-zinc alloy powder; the powder A is copper-zinc alloy powder with 300 meshes; the other conditions were the same as in example 1.
Example 5:
compared with example 1, the difference is only that powder B is 1000-mesh copper-zinc alloy powder; the powder A is copper-zinc alloy powder with 300 meshes; the other conditions were the same as in example 1.
Example 6:
compared with the example 1, the difference is only that the powder B is 500-mesh copper-zinc alloy powder, and the particle A is 300-mesh pure copper powder; the other conditions were the same as in example 1.
Comparative example 1:
compared with the embodiment 1, the difference is that only 200 meshes of copper-zinc alloy powder is selected and uniformly paved in a high-purity graphite die with the inner diameter of 14 mm, and the paving height is 0.5 mm. The other conditions were the same as in example 1.
Comparative example 2:
compared with the embodiment 1, the difference is that only 500-mesh copper-zinc alloy powder is selected and uniformly spread in a high-purity graphite die with the inner diameter of 14 mm, and the spreading height is 0.5 mm. The other conditions were the same as in example 1.
Comparative example 3:
compared with the example 1, the difference is only that the preparation method of the selected raw material powder is an air atomization method, namely, the raw material powder is spherical powder. The other conditions were the same as in example 1.
Comparative example 4:
compared with the example 1, the difference is only that one-stage sintering is adopted, for example, the temperature is directly raised to 800 ℃ at the speed of 5 ℃/min, and the temperature is kept for 3h (the 600 ℃ heat preservation treatment is omitted). The other conditions were the same as in example 1. After the sintering process is finished, the die is taken out, and the powder is not formed and still takes a single granular shape, which indicates that the heat preservation time is insufficient, sintering necks with enough strength are not formed among powder granules, and the sintering fails.
The materials obtained in each case were subjected to electrochemical measurements using the assembly method of example 1, and the data are shown in table 1:
TABLE 1
Therefore, the material prepared by the method has better electrochemical performance.