CN116014093A - High-conductivity functional group heterogeneous-phase connection material at zinc grain boundary and preparation method thereof - Google Patents
High-conductivity functional group heterogeneous-phase connection material at zinc grain boundary and preparation method thereof Download PDFInfo
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- UOURRHZRLGCVDA-UHFFFAOYSA-D pentazinc;dicarbonate;hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[O-]C([O-])=O.[O-]C([O-])=O UOURRHZRLGCVDA-UHFFFAOYSA-D 0.000 claims description 2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a zinc grain boundary high-conductivity functional group heterogeneous-connected material and a preparation method thereof; the multidimensional zinc metal and high-conductivity carbon nano tube composite material is formed by a ball milling-high-speed heating solidification method. Meanwhile, the conductive carbon nanotubes are bridged with each other to form a conductive network. In the prepared composite material, the high-conductivity carbon material forms a strip-shaped conductive network at boundary aggregates of zinc grain boundaries, and is uniformly wound and staggered. The preparation method has the advantages of simple preparation flow, controllable process, good stability, mass production and suitability for mass preparation.
Description
Technical Field
The invention belongs to the technical field of battery materials, relates to a heterogeneous connected composite material and a preparation method thereof, and in particular relates to a heterogeneous connected material with high-stability zinc grain boundary high-conductivity functional groups and a preparation method thereof.
Background
The successive exhaustion of traditional fossil energy and the increasing energy demand promote the efficient utilization of clean energy such as solar energy, wind energy and the like and the transformation and upgrading of energy structures. However, the application of these natural renewable energy sources is susceptible to geographical conditions, climatic natural environments, has intermittent, random characteristics, etc., and is always difficult to directly incorporate into existing power grids. The wind/photoelectric energy obtained intermittently can be effectively stored and effectively and smoothly generated and output by utilizing a large-scale battery stack energy storage technology. At present, the large-scale electrochemical energy storage mainly comprises a lithium battery and a lead-acid battery, but the requirement of large-scale energy storage is difficult to meet due to the characteristics of unsafe property, high price, poor lead-acid cycling stability, high toxicity and the like of lithium. Therefore, development of high-safety, high-stability, low-cost, environment-friendly batteries remains an important point of future battery research.
The energy storage technology of the water-based zinc ion battery is widely paid attention to society, and the main advantage of the water-based zinc ion battery is that: 1. has a theoretical high capacity (820 mAh g) -1 ) The method comprises the steps of carrying out a first treatment on the surface of the 2. Has low oxidation/reduction potential (-0.762V), and can be used for oxidation-reduction reaction with multiple multivalent oxides; 3. zinc can exist stably in air and water, and has high safety; 4. the resources are rich. This series of advantages makes aqueous zinc ion batteries one of the most potential and valuable large-scale stack energy storage technologies. However, there are some problems in the actual use of zinc ions. For example, zinc dendrites grown during cycling can puncture the separator to cause a short circuit in the battery, resulting in severe degradation of the battery cycling performance; side reactions such as corrosion and passivation of the surface of the negative electrode seriously reduce the metal utilization rate and the cycle life, which affect the electricityElectrochemical performance of the cell as a whole. Currently, the modification means for the above problems are mainly surface modification at the zinc anode-electrolyte interface. Such as Zhao et al by building ultra-thin TiO on the surface of zinc foil 2 The coating effectively prevents zinc metal from being directly exposed in electrolyte, and achieves the aim of inhibiting dendrite growth during zinc deposition (Adv Mater Interfaces,2018, 5:1800848). Wan et al in ZnSO 4 Na-containing electrolyte is added + The ionic additives are effective in promoting uniform deposition of zinc ions by electrostatic shielding effects (Nat Commun,2018, 9:1656). However, the method can only effectively improve the surface utilization rate, and has the hidden trouble of coating stripping, additive failure and the like under high-current charge and discharge.
The construction of the three-dimensional structure zinc anode on the carbon substrate through bulk phase design is one of effective strategies for solving the problems of low surface utilization rate and poor deep charge and discharge performance. The carbon not only can ensure the rapid transfer of electrons and reduce the zinc nucleation overpotential, but also can realize the high-reversibility and uniform zinc deposition and stripping; and also can provide guiding Zn 2+ Is provided, the ion channel of the migration path of (a) is provided. At present, in the preparation of a zinc-carbon negative electrode composite material with a three-dimensional structure, an array frame is mainly constructed in situ by a calcination template method, or zinc metal is electrodeposited on a porous carbon substrate. However, such methods have long implementation period and require a large amount of energy (such as heat energy and electric energy) to consume, which results in too high production cost and failure of large-scale and batch production. Moreover, due to the weak binding force of physically bonded carbon materials, the materials are unevenly compounded during sintering and deposition, resulting in serious carbon aggregation or poor structural stability, which greatly affects the cycle stability of the battery.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a zinc grain boundary heterogeneous material with high conductivity functional groups and high stability based on a ball milling-high-speed heating solidification method short process and a preparation method thereof, which effectively solve the problems of long preparation process, weak carbon binding capacity and the like of a three-dimensional structure carbon zinc cathode, and the prepared composite material has high cycle stability and high conductivity and extremely high practical value.
The invention aims at realizing the following technical scheme:
the invention relates to a zinc grain boundary high-conductivity functional group heterogeneous connection material, wherein high-conductivity carbon materials in the material form a uniformly-wound staggered strip-shaped conductive network, and all grain boundary aggregates of zinc particles are connected to form a complete uniform bridging structure.
As one embodiment, the highly conductive carbon material is a nano carbon material having a conjugated carbon skeleton, such as a composite carbon material containing an aspect ratio linear carbon material and one or more combinations of graphene, graphene oxide, acetylene black, and carbon black; the length-diameter ratio linear carbon material is a carbon nano tube or a carbon fiber.
As one embodiment, the zinc particles comprise one or more of zinc powder, zinc paste, zinc oxide powder, basic zinc carbonate; zinc powder and zinc paste are preferable.
The invention also relates to a preparation method of the zinc grain boundary high-conductivity functional group heterogeneous-connected material, which is prepared by adopting a ball milling-high-speed heating solidification process.
The ball milling is to transfer the mixture of zinc powder, high-conductivity carbon material and process control agent into a high-speed ball mill, and perform variable-speed ball milling step by step or for multiple times to obtain a carbon material mixed zinc powder material with high uniform mixing; the high-speed heating and curing is carried out after the obtained carbon material mixed zinc powder material is put into a die; and (3) placing the carbon material mixed zinc powder material into a plasma machine for rapid heating treatment, and performing high-speed heating and curing treatment on the carbon material mixed zinc powder material by utilizing axial force and pulse current to form a carbon-metal zinc block material with uniform and controllable size and thickness. In terms of technology, the invention realizes the short-flow preparation of the carbon-zinc composite material by a ball milling-high-speed heating solidification technology. Meanwhile, in the structure, not only the physical and mechanical property loss of the material is small, but also the problems of poor physical combination effect of carbon and the like are effectively solved, and the uniform mixing of the porous carbon material and the metal zinc is realized. In addition, the strip-shaped conductive network formed by the high-conductivity carbon material on the boundary aggregate of the zinc grain boundaries effectively inhibits side reactions of the boundary of zinc metal grain boundaries, and is beneficial to reversible deposition and stripping of zinc.
As one embodiment, the preparation method of the zinc grain boundary heterogeneous-connected material with high conductivity functional groups comprises the following steps:
s1, pretreatment: and (3) transferring the high-conductivity carbon material and the process control agent into a low-oxygen environment for protection, adding an anhydrous solvent, and mixing with the powder zinc material.
S2, ball milling treatment: transferring the mixed material obtained in the step S1 into a high-speed ball mill, and performing variable-speed ball milling treatment to obtain a carbon material mixed zinc powder material with high uniform mixing;
s3, high-speed heating and curing: putting the carbon material mixed zinc powder material obtained in the step S2 into a die; the powder is heated and solidified at high speed by using axial force and pulse current.
In the step S1, the high-conductivity carbon material (carbon material aggregate) has lighter texture and smaller density, is easy to suspend in air, is inconvenient for direct ball milling, and is difficult to uniformly mix with the metal powder. The addition of the process control agent reduces the accumulation and agglomeration of the powder in the ball milling process, so that the metal zinc powder and the light carbon material aggregate are uniformly mixed, and the powder yield is improved.
In the step S3, the high-speed heating and curing are that the flattened carbon material zinc-metal mixture is rapidly cured by utilizing axial force and pulse current under 20-75 MPa. In the rapid sintering state, the zinc powder material generates a large number of free electrons which drift directionally, and the free electrons are combined with electrons of the light carbon material aggregate, zinc is connected with the high-conductivity functional group heterogeneous bridge at the zinc crystal boundary, so that the high-conductivity and high-stability block composite material connected with the high-conductivity functional group heterogeneous bridge at the zinc crystal boundary is rapidly formed.
As an embodiment, in step S1, the anhydrous solvent is one or more of anhydrous toluene, anhydrous methanol, anhydrous ethanol, anhydrous N, N-dimethylformamide, anhydrous dichloromethane, anhydrous acetone, anhydrous carbon tetrachloride, and anhydrous N-hexane. Preferably added zinc metal powder material: mass of anhydrous solvent: the volume ratio is 3:1-15:1.
As an embodiment, in step S1, the process control agent is one or more of stearic acid, sodium stearate, titanate. The addition amount of the process control agent is small, so that insufficient grinding is caused; the addition amount is large, which causes more impurities of the carbon-zinc powder material and is unfavorable for the subsequent sintering, curing and forming. Therefore, the mass ratio of the process control agent to the zinc-carbon mixed material is preferably 1:15 to 1:45.
As an embodiment, in step S1, the low oxygen environment is a dry low oxygen environment having both water and oxygen content below 1 ppm. Since metallic zinc powder is hygroscopic, protection is required in a dry low oxygen environment where both water and oxygen content are below 1 ppm.
As an embodiment, the content of highly conductive carbon material in the resulting zinc-carbon mixture will play an important role in the electrochemical performance of the composite. Too low a mass to exert the effect of improving conductivity; the occupied quality is high, the performance improving effect tends to be saturated, and the material formed by subsequent sintering is crisp and soft, so that the storage and the actual use are not facilitated. Therefore, the mass percentage content of the high-conductivity carbon material in the carbon material mixed zinc powder material obtained in the step S2 is preferably 2-10wt%.
As an embodiment, in step S2, the ball milling is performed in a divided or continuous manner. The wet ball milling can lead the light carbon material and the zinc powder material to be more uniformly mixed and stably to carry out surface contact and compounding. The ball milling rotating speed is too low or the time is too short, so that the two-phase substances are easy to mix unevenly; the dry ball mill rotates too high or too long, so that energy is wasted and the efficiency is low. Therefore, the rotating speed is controlled to be 100-1600r/min, the time is 10-60 min, the material temperature is controlled to be 20-90 ℃, and the ball-material ratio is controlled to be 10: 1-20: 1. preferably, the rotating speed is 400-1600 r/min, and the ball-to-material ratio is 10:1, temperature 35 ℃.
As one embodiment, in step S3, the scale mold is one or more of a cylinder type, a cube type. The diameter of the cylindrical die is 1-5 cm, and the height is 0.3-2 cm. A die with a diameter of 1cm and a height of 0.5cm is preferably used as a powder container for loading ball milling, and the flattening pressure is preferably 8MPa.
As one embodiment, in step S3, the temperature increase rate is 50 ℃/min.
As one embodiment, in step S3, the high-speed heating curing (plasma sintering) temperature is 200-700 ℃, the heat preservation time is 5-30 min, and the axial force pressure is 20-75 MPa.
As an embodiment, from the pretreatment, the subsequent process is conducted in a dry low oxygen environment with water and oxygen content of less than 1ppm, otherwise it is prone to oxidation of metallic zinc.
Compared with the prior art, the invention has the following beneficial effects:
1) The ball milling-high-speed heating solidification process adopted by the invention is used for preparing the high-conductivity functional group heterogeneous material at the zinc grain boundary, the method is simple, the process is stable, the preparation flow is short, the uniform composite material of the carbon material and the metallic zinc can be realized in a mild and dry environment, and the material can be produced in a large scale;
2) In the produced composite material, the high-conductivity carbon material forms a strip-shaped conductive network at boundary aggregates of zinc grain boundaries, and is uniformly wound and staggered; the special bridging structure effectively inhibits side reactions of zinc metal grain boundary boundaries, and is beneficial to reversible deposition and stripping of zinc;
3) The produced zinc grain boundary high-conductivity functional group heterogeneous-connected material has excellent conductivity and structural stability, is a high-stability functional material required by a water-based zinc-based battery, and is expected to be used in the energy field on a large scale;
4) In the heterogeneous linked composite material synthesized in the present invention, there is no simple compounding at the physical level. In the heating and curing process, the interface of the conductive carbon material and the metallic zinc is connected through the grain boundary to form firm combination due to the strong electric field acting force provided by the plasma machine. The high-conductivity carbon material plays a role of an electron bridge at a zinc-zinc interface, so that electrons are ensured to be transferred quickly, an electric field in a zinc bulk phase is regulated, and the stability of the material in electrochemical circulation is improved. The zinc-carbon composite material obtained by the vacuum hot-pressing sintering procedure just uses high temperature and high pressure to shape the powder into a block substance, and can not form the heterogeneous connected special structure at the zinc grain boundary. In addition, the temperature and pressure required by the vacuum hot-pressing sintering procedure are far higher than those of the rapid heating curing method used in the invention, so that the grain size of zinc grains in the battery is large, the zinc is too compact in the battery, and zinc is unevenly deposited and peeled on the surface of the block in the battery cycle process, so that dendrite growth and uneven deposition of zinc are aggravated, and the electrochemical performance is affected.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a flow chart of a ball milling-high speed heating curing process;
FIG. 2 is a TEM image of a carbon nanotube;
FIG. 3 is a TEM image (50 nm) of a high conductivity functional group heterogeneous connected material at a zinc grain boundary with high stability;
FIG. 4 is a TEM image (5 nm) of a high conductivity functional group heterogeneous connected material at a zinc grain boundary with high stability;
FIG. 5 is an XRD pattern of a highly conductive functional group heterogeneous linked material at zinc grain boundaries of high stability;
FIG. 6 is an internal resistance diagram of a high conductivity functional group heterolinked material at a high stability zinc grain boundary;
FIG. 7 is a graph of symmetric cell performance for high conductivity functional group heterojoined materials at high stability zinc grain boundaries;
FIG. 8 is a SEM image after circulation of preparing a high conductivity functional group heterogeneous connected material at zinc grain boundaries by ball milling-high speed heat curing;
FIG. 9 is a SEM image after a simple mix-high speed heat cure process for preparing a zinc anode material;
fig. 10 is a SEM image after cycling of the zinc-agglomerated composite obtained using only ball milling and vacuum hot-pressed sintering.
Detailed Description
The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that several modifications and improvements can be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
Example 1
In the embodiment, the carbon nano tube and zinc powder are used as raw materials to prepare the high-conductivity functional group heterogeneous material at the zinc grain boundary with high stability, and the preparation method is a ball milling-high-speed heating and curing process, as shown in fig. 1:
(1) Pretreatment: transferring 0.4g of high-conductivity carbon material carbon nano tube and 0.4g of process control agent stearic acid into argon protection of low water and low oxygen, adding 3mL of absolute ethyl alcohol, and mixing with 10g of zinc metal powder. The microscopic size diagram of the high-conductivity carbon material is shown in fig. 2.
(2) High-energy ball milling treatment: transferring the mixed material obtained in the previous step into a high-speed ball mill, and maintaining the mixed material for 1h at a rotating speed of 400rpm under the protection of sufficient argon, wherein the ball-material ratio is 10:1, controlling the reaction temperature to be about 35 ℃ to obtain the carbon material mixed zinc powder material with high uniform mixing.
(3) High-speed heating and curing: the obtained carbon material-mixed zinc powder material was put into a die of a specific size scale (a cylindrical die having a diameter of 1cm and a height of 0.5 cm) and flattened at a pressure of 8MPa. And (3) performing rapid heating treatment in a plasma machine, wherein the heating rate is 50 ℃/min, the sintering temperature is 350 ℃, the heat preservation time is 10min, and the applied axial force pressure in the plasma machine is 50MPa. The powder is heated and solidified at high speed by using axial force and pulse current. A high conductivity and high stability bulk composite material is formed in which zinc grain boundaries are connected to high conductivity functional group heterobridges.
Fig. 3 to 8 are respectively a TEM image, an XRD image, an internal resistance image of a zinc cell, a symmetrical cell image and an SEM image after long-time circulation of the prepared zinc grain boundary heterogeneous-phase material with high conductivity functional groups. As can be seen from fig. 3 and 4, there are a large number of heterogeneous connected, inter-entangled carbon nanotubes between the zinc-zinc particles. The carbon nanotubes play a role of bridging among grain boundaries, and internal resistance at the grain boundaries is reduced. As can be seen from FIG. 5, the composite material has zinc onlyAnd a peak indicating that the process may not change the structure of the material or generate other phases. As can be seen from fig. 6, compared with the cell assembled by the zinc sheets obtained by the preparation method of the present invention, the internal resistance of the zinc ion cell constructed by the composite material is significantly reduced, which is only about 10Ω. As can be seen from FIG. 7, the flow rate is 1A/cm 2 The composite material synthesized by the preparation method of the invention has smaller polarization and shows ultra-long cycle stability of more than 240 hours. Figure 8 shows that the electrode surface after long cycling is still uniform and smooth and no dendrite formation occurs.
Example 2
In the embodiment, the carbon nano tube, the carbon black and the zinc powder are used as raw materials to prepare the high-conductivity functional group heterogeneous material at the zinc grain boundary with high stability, and the preparation method is a ball milling-high-speed heating and curing process.
(1) Pretreatment: transferring 0.3g of high-conductivity carbon material carbon nano tube, 0.3g of carbon black and 0.3g of process control agent stearic acid into low-water low-oxygen argon protection, adding 3mL of absolute ethyl alcohol, and mixing with 10g of zinc metal powder.
(2) High-energy ball milling treatment: transferring the mixed material obtained in the previous step into a high-speed ball mill, and maintaining the mixed material for 1h at the rotating speed of 600rpm under the protection of sufficient argon, wherein the ball-material ratio is 10:1, controlling the reaction temperature to be about 35 ℃ to obtain the carbon material mixed zinc powder material with high uniform mixing.
(3) High-speed heating and curing: the obtained carbon material-mixed zinc powder material was put into a die of a specific size scale (a cylindrical die having a diameter of 1cm and a height of 0.5 cm) and flattened at a pressure of 8MPa. And (3) carrying out rapid heating treatment in a plasma machine, wherein the heating rate is 50 ℃/min, the sintering temperature is 350 ℃, the heat preservation time is 10min, and the axial force pressure is 50MPa. The powder is heated and solidified at high speed by using axial force and pulse current. A high conductivity and high stability bulk composite material is formed in which zinc grain boundaries are connected to high conductivity functional group heterobridges. The composite material synthesized by the preparation method of the invention has higher cycle stability of 1A/cm 2 The cycle duration at current density is 180h. Also shows higher conductivity and internal resistanceOnly about 15 omega.
Example 3
The preparation method adopts carbon nano tube and zinc oxide as raw materials to prepare the high-conductivity functional group heterogeneous-phase connected material at the zinc grain boundary with high stability, and the preparation method adopts a ball milling-high-speed heating solidification process.
(1) Pretreatment: transferring 0.3g of high-conductivity carbon material carbon nano tube and 0.2g of process control agent stearic acid into argon protection of low water and low oxygen, adding 2mL of absolute ethyl alcohol, and mixing with 8g of zinc oxide powder.
(2) High-energy ball milling treatment: and (3) transferring the mixed material obtained in the previous step into a high-speed ball mill, maintaining the speed of 600rpm for 1h under the protection of sufficient argon, controlling the ball-material ratio to be 15:1, and controlling the reaction temperature to be about 35 ℃ to obtain the carbon material mixed zinc powder material with high uniform mixing.
(3) High-speed heating and curing: the obtained carbon material-mixed zinc powder material was put into a die of a specific size scale (a cylindrical die having a diameter of 1cm and a height of 0.5 cm) and flattened at a pressure of 8MPa. And (3) carrying out rapid heating treatment in a plasma machine, wherein the heating rate is 50 ℃/min, the sintering temperature is 450 ℃, the heat preservation time is 10min, and the axial force pressure is 50MPa. The powder is heated and solidified at high speed by using axial force and pulse current.
The composite material synthesized by the preparation method provided by the invention has higher cycle stability, and the cycle time is 120h under the current density of 1A/cm < 2 >. Also shows higher conductivity, and the internal resistance is only about 32 omega.
Comparative example 1
Zinc powder is used as raw material, and the metal zinc material is prepared only by high-speed heating and curing without ball milling treatment.
High-speed heating and curing: 10g of zinc powder is put into a die with a specific size scale, a cylindrical die with a diameter of 1cm and a height of 0.5cm, and flattened under a pressure of 8MPa. And (3) carrying out rapid heating treatment in a plasma machine, wherein the heating rate is 50 ℃/min, the sintering temperature is 350 ℃, the heat preservation time is 10min, and the axial force pressure is 50MPa. Obtaining the massive metallic zinc anode material.
As shown in fig. 7, the obtained zinc material was not subjected to the carbon mixing treatment, and its internal resistance was not improved, 200 Ω. Even at a current density of 1A/cm2, a polarization voltage of approximately 50mV is exhibited. And short circuit of the battery occurs at 40 hours due to the large growth of zinc dendrites during charge and discharge.
Comparative example 2
The zinc-carbon composite negative electrode material is prepared by taking zinc powder and carbon nano tubes as raw materials, adopting simple mixing treatment and then rapidly heating and curing.
(1) 0.4g of the highly conductive carbon material carbon nano tube and 10g of zinc powder are subjected to simple mechanical grinding and mixing for 30min under the argon atmosphere.
(2) High-speed heating and curing: zinc powder is placed in a die of a specific size, such as a cylindrical die with a diameter of 1cm and a height of 0.5cm, and flattened at a pressure of 8MPa. And (3) carrying out rapid heating treatment in a plasma machine, wherein the heating rate is 50 ℃/min, the sintering temperature is 350 ℃, the heat preservation time is 10min, and the pressure is 50MPa. Obtaining the zinc-carbon composite anode material.
The internal resistance of this comparative example was 187 Ω. Although the addition of the conductive carbon material reduces the internal resistance of the battery, the effect is not great. And at 1A/cm 2 The cycle life is only 46h at a current density of (c). SEM testing was performed on the electrodes after the end of the cycle, as shown in fig. 9. Under short charge and discharge times, a large number of dendrites form at the electrode-electrolyte interface, indicating that the simply mixed composite material is not effective for uniform deposition of zinc ions, resulting in micro-shorting of the cell.
Comparative example 3
Zinc powder and carbon nano tubes are used as raw materials, high-speed heating and curing are not adopted, and ball milling treatment and vacuum hot pressing and curing treatment are only adopted, so that the blocky composite material is prepared.
(1) Pretreatment: transferring 0.4g of high-conductivity carbon material carbon nano tube and 0.4g of process control agent stearic acid into argon protection of low water and low oxygen, adding 3mL of absolute ethyl alcohol, and mixing with 10g of zinc metal powder.
(2) High-energy ball milling treatment: transferring the mixed material obtained in the previous step into a high-speed ball mill, and maintaining the mixed material for 1h at the rotating speed of 600rpm under the protection of sufficient argon, wherein the ball-material ratio is 10:1, controlling the reaction temperature to be about 35 ℃ to obtain the carbon material mixed zinc powder material with high uniform mixing.
(3) Vacuum hot press curing: and (3) putting the obtained carbon-zinc mixed material into a vacuum hot-pressing sintering die. And (3) hot-pressing and sintering in a vacuum hot-pressing furnace, wherein the pressing pressure is 180MPa, the sintering temperature is 550 ℃, and the sintering time is 600min, so that the carbon nano tube and zinc block composite material is prepared.
The internal resistance of this comparative example was 193 Ω. At 1A/cm 2 The cycle life is only 38h at a current density of (c). SEM testing was performed on the electrodes after the end of the cycle, as shown in fig. 10. Under the condition of short-time charge and discharge, the interface between the electrode and the electrolyte is found to be rugged, so that the micro short circuit of the battery is caused. The zinc-carbon composite material which is not subjected to high-speed heating and curing treatment cannot form a heterogeneous connection structure with the conductive functional group at a zinc crystal boundary, and the zinc-carbon composite material cannot play a role in improving key performances such as conductivity, circulation stability and the like. In addition, under the high-pressure and high-temperature treatment of the vacuum hot-pressing technology, the inside of the block is too compact, zinc ions are unevenly deposited/stripped and easily exist on the surface of the block in the charge-discharge process, so that zinc dendrite growth and uneven deposition phenomena are aggravated, and the circulation stability of the block is reduced.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the invention.
Claims (10)
1. A zinc grain boundary high-conductivity functional group heterogeneous connection material is characterized in that high-conductivity carbon materials in the material form a uniformly-wound and staggered strip-shaped conductive network, and all grain boundary aggregates of zinc particles are connected to form a complete uniform bridging structure.
2. The heterogeneous continuous material of high conductivity functional groups at zinc grain boundaries according to claim 1, wherein the high conductivity carbon material is a nanocarbon material having a conjugated carbon skeleton, and comprises a composite carbon material comprising an aspect ratio linear carbon material and one or more combinations of graphene, graphene oxide, acetylene black, and carbon black; the length-diameter ratio linear carbon material is a carbon nano tube or a carbon fiber.
3. The high conductivity functional group hetero-connected material at zinc grain boundaries of claim 1 wherein said zinc particles comprise one or more of zinc powder, zinc paste, zinc oxide powder, basic zinc carbonate.
4. A method for preparing a material with heterogeneous connection of highly conductive functional groups at zinc grain boundaries according to claim 1, comprising the following steps:
s1, pretreatment: transferring the high-conductivity carbon material and the process control agent into a low-oxygen environment for protection, adding an anhydrous solvent, and mixing with the powder zinc material;
s2, ball milling treatment: transferring the mixed material obtained in the step S1 into a high-speed ball mill, and performing variable-speed ball milling treatment to obtain a carbon material mixed zinc powder material;
s3, high-speed heating and curing: putting the carbon material mixed zinc powder material obtained in the step S2 into a die; and (3) placing the carbon material mixed zinc powder material into a plasma machine to quickly heat, and realizing high-speed heating and solidification of the carbon material mixed zinc powder material by utilizing axial force and pulse current.
5. The method for preparing a heterogeneous continuous material of highly conductive functional groups at zinc grain boundaries according to claim 4, wherein in the step S1, the anhydrous solvent is one or more of anhydrous toluene, anhydrous methanol, anhydrous ethanol, anhydrous N, N-dimethylformamide, anhydrous dichloromethane, anhydrous acetone, anhydrous carbon tetrachloride, and anhydrous N-hexane.
6. The method for preparing heterogeneous connected materials with high conductivity functional groups at zinc grain boundaries according to claim 4, wherein in the step S1, the process control agent is one or more of stearic acid, sodium stearate and titanate.
7. The method for preparing a heterogeneous continuous material of highly conductive functional groups at zinc grain boundaries according to claim 4, wherein in step S1, the low oxygen environment is a dry low oxygen environment with water and oxygen content of less than 1 ppm; in the step S2, ball milling is carried out in times or continuously, the rotating speed is 100-1600r/min, the time is 10-60 min, and the material temperature is 20-90 ℃.
8. The preparation method of the zinc grain boundary heterogeneous connected material with high conductivity functional groups, which is disclosed in claim 4, is characterized in that the mass percentage content of the high conductivity carbon material in the carbon material mixed zinc powder material obtained in the step S2 is 2-10wt%.
9. The method for preparing a heterogeneous continuous material of high conductivity functional groups at zinc grain boundaries with high stability according to claim 4, wherein in the step S3, the mold is one or more of a cylinder type and a cube type, and has a diameter of 1-5 cm and a height of 0.3-2 cm.
10. The method for preparing a heterogeneous material with high conductivity functional groups at zinc grain boundaries, which is characterized by the high-stability zinc grain boundaries according to claim 4, wherein in the step S3, the high-speed heating and curing temperature is 200-700 ℃, the heat preservation time is 5-30 min, and the axial force pressure is 20-75 MPa.
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