CN116443887A - Preparation method of porous vermiculite nano sheet, porous vermiculite nano sheet and negative electrode of water system zinc ion battery - Google Patents

Preparation method of porous vermiculite nano sheet, porous vermiculite nano sheet and negative electrode of water system zinc ion battery Download PDF

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CN116443887A
CN116443887A CN202310487643.2A CN202310487643A CN116443887A CN 116443887 A CN116443887 A CN 116443887A CN 202310487643 A CN202310487643 A CN 202310487643A CN 116443887 A CN116443887 A CN 116443887A
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vermiculite
porous
zinc
nano sheet
porous vermiculite
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周光敏
郑志扬
钟熊伟
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Shenzhen International Graduate School of Tsinghua University
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Shenzhen International Graduate School of Tsinghua University
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Abstract

The invention provides a preparation method of porous vermiculite nano sheets, which comprises the following steps: dispersing vermiculite in water, and then simultaneously carrying out mechanical stirring and ultrasonic crushing to obtain a suspension containing vermiculite flakes; carrying out solid-liquid separation on the suspension to obtain a supernatant; and freeze-drying the supernatant to obtain the porous vermiculite nano sheet. The porous vermiculite nano sheet prepared by the method can be single-layer or multi-layer, has an atomic porous structure, can effectively protect a zinc anode when being used as a protective layer of the zinc anode, promotes the rapid transmission of zinc ions, inhibits the occurrence of side reactions, controls the deposition behavior of zinc, further realizes the dendrite-free zinc anode, and improves the overall performance of the battery. The invention also provides the porous vermiculite nano sheet prepared by the preparation method and a water system zinc ion battery cathode applying the porous vermiculite nano sheet.

Description

Preparation method of porous vermiculite nano sheet, porous vermiculite nano sheet and negative electrode of water system zinc ion battery
Technical Field
The invention relates to the field of water-based zinc ion batteries, in particular to a preparation method of porous vermiculite nano sheets, the porous vermiculite nano sheets and a negative electrode of the water-based zinc ion battery.
Background
The water-based zinc ion battery has great application prospect in the fields of portable mobile electronic equipment, electric automobiles and the like due to the advantages of high natural abundance of a zinc negative electrode, high theoretical specific capacity (820 mAh/g), low oxidation-reduction potential (-0.76V vs. SHE), high use safety of water-based electrolyte and the like. However, the problems of hydrogen evolution, corrosion, dendrite growth and the like in the zinc cathode seriously affect the cycle stability and coulombic efficiency of the zinc ion battery. The current scientific research workers mainly solve the problems of the zinc cathode from the aspects of interface coating design, electrolyte modification, diaphragm modification and the like. The method for designing the zinc anode coating has the advantages of low cost, simple process and the like, and is widely paid attention to. However, the zinc cathode coating protection tends to easily cause problems of low ionic conductivity, increased interfacial polarization, and the like, reducing the practicality of the battery. Further improvements in coating design, in turn, can complicate the process and increase material costs, compromising the low cost advantage of zinc ion batteries.
Vermiculite is a natural two-dimensional clay mineral and has the advantages of low cost, high mechanical property, excellent hydrophilicity and the like. In addition, vermiculite also has metal ion adsorption capacity and can regulate and control Zn 2+ Is expected to economically improve the overall electrochemical performance of the battery. However, vermiculite is directly used as a protective layer of a zinc cathode of the water-based zinc ion battery, so that the transmission of ions in the battery can be greatly hindered, and the problems of high polarization voltage, poor multiplying power performance and the like of the battery are caused. Although the prior art has studied to use clay materials such as vermiculite as protective layer materials after grinding or chemical intercalation stripping treatment, and can improve the problems of zinc cathode to a certain extent, the prior art has complex process, high cost and large pollution on the vermiculite and can not realize the structural design of vermiculite atomic levelThus, the improvement of the electrochemical performance of the entire subsequent battery is very limited.
Disclosure of Invention
In order to solve the defects in the prior art, the preparation method of the porous vermiculite nano sheet is simple to operate and low in cost, and the prepared porous vermiculite nano sheet has an atomic-level porous structure, is used as a zinc anode protection layer, can construct a rapid transmission channel for ions, greatly improves the stability of a zinc anode of a water-based zinc ion battery and the overall cycle life of the battery, and simultaneously reduces the cost of zinc anode protection.
In addition, the invention also provides the porous vermiculite nano sheet prepared by the preparation method.
In addition, the invention also provides a water-based zinc ion battery anode comprising the porous vermiculite nano sheet.
In order to achieve the above purpose, the present invention provides a method for preparing porous vermiculite nano sheets, comprising the steps of:
dispersing vermiculite in water, and then simultaneously carrying out mechanical stirring and ultrasonic crushing to obtain a suspension containing vermiculite flakes;
carrying out solid-liquid separation on the suspension to obtain a supernatant;
and freeze-drying the supernatant to obtain the porous vermiculite nano sheet.
The invention also provides the porous vermiculite nano sheet prepared by the preparation method.
The invention also provides a water-based zinc ion battery anode, which comprises a zinc anode and a protective layer arranged on the surface of the zinc anode, wherein the material of the protective layer comprises a binder and the porous vermiculite nano sheet.
Compared with the prior art, the porous vermiculite nano sheet prepared by adopting mechanical stirring and ultrasonic crushing simultaneously has an atomic-level porous structure, high mechanical strength and good hydrophilicity, and the preparation method is simple, low in cost and free from environmental pollution, and is suitable for large-scale batch preparation. When the porous vermiculite nano sheet is used as a protective layer of a zinc cathode, the direct contact between the zinc cathode and electrolyte can be isolated, the zinc cathode can be effectively protected, side reactions are restrained, corrosion is slowed down, the rapid transmission of zinc ions is promoted, meanwhile, the overpotential of deposited zinc is reduced, the plane directional deposition of zinc is induced, the growth of dendrites is restrained, and the overall electrochemical performance of the battery is further improved.
Drawings
FIG. 1 is a surface atomic force microscope image of a porous vermiculite nano sheet (PVMT) prepared in example 1 of the present invention.
Fig. 2 is a cross-sectional scanning electron microscope image of the negative electrode (pvmt@zn) of the aqueous zinc-ion battery prepared in example 1 of the present invention.
Fig. 3 (a) is the contact angle of pure zinc negative electrode (Bare Zn) with deionized water; fig. 3 (b) shows the contact angle between the negative electrode (pvmt@zn) of the aqueous zinc-ion battery prepared in example 1 of the present invention and deionized water.
FIG. 4 is a surface atomic force microscope image of non-porous vermiculite Nanoplatelets (NVMTs) prepared according to comparative example 1 of the present invention.
Fig. 5 is an electrochemical impedance graph of pvmt@zn|pvmt@zn symmetrical battery and barezn|barezn symmetrical battery prepared in example 1 of the present invention, and of the nvmt@zn|nvmt@zn symmetrical battery prepared in comparative example 1 in an initial state.
FIG. 6 shows a PVMT@Zn|PVMT@Zn symmetrical battery and a BareZn|BareZn symmetrical battery at 10mA/cm, which are prepared in example 1 of the present invention 2 、1mAh/cm 2 Charge-discharge cycle graph under test conditions.
FIG. 7 (a) shows that the PVMT@Zn|PVMT@Zn symmetric cell prepared in example 1 of the present invention was at 10mA/cm 2 、1mAh/cm 2 Surface scanning electron microscope pictures after 40h of circulation under test conditions; FIG. 7 (b) is a surface scanning electron microscope image of the PVMT@Zn negative electrode surface of FIG. 7 (a) after the protective layer is removed; FIG. 7 (c) is a 10mA/cm symmetric battery with Bare Zn 2 、1mAh/cm 2 Surface scanning electron microscope images after 40h of circulation under test conditions.
FIG. 8 shows a PVMT@Zn|PVMT@Zn symmetrical battery and a BareZn|BareZn symmetrical battery at 50mA/cm, which are prepared in example 1 of the present invention 2 、1mAh/cm 2 Charge-discharge cycle graph under test conditions.
FIG. 9 shows PVMT@Zn||MnO prepared in example 1 of the present invention 2 Full cell and pore Zn MnO 2 Coulombic efficiency curve for a full cell at 616mA/g test conditions.
FIG. 10 shows PVMT@Zn||MnO prepared in example 1 of the present invention 2 Full cell and pore Zn MnO 2 Cycling profile for a full cell at 616mA/g test conditions.
Detailed Description
Embodiments of the present invention are described in detail below. The following examples are illustrative only and are not to be construed as limiting the invention.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
An embodiment of the present invention provides a method for preparing porous vermiculite nano sheets, including the steps of:
dispersing vermiculite in water, and then simultaneously carrying out mechanical stirring and ultrasonic crushing to obtain a suspension containing vermiculite flakes;
carrying out solid-liquid separation on the suspension to obtain a supernatant;
and freeze-drying the supernatant to obtain the porous vermiculite nano sheet.
The applicant has found through extensive research that conventional treatments of vermiculite using single grinding, mechanical agitation or ultrasonic disruption often only apply shear forces in a single direction to the vermiculite. The vermiculite sheets are weak in interlayer bonding, and although the vermiculite sheets are easy to peel, the vermiculite sheets are strong in bonding force in the plane of the crystal lattice, so that the atomic-level pore forming is difficult to realize. According to the invention, mechanical stirring and ultrasonic crushing are adopted simultaneously, which is equivalent to simultaneously applying longitudinal and transverse shearing forces to vermiculite in solution, wherein the transverse shearing forces enable vermiculite sheets to be peeled off, and the longitudinal shearing forces enable vermiculite in-plane pore forming to obtain the porous vermiculite nano sheet with an atomic-scale pore structure. Compared with the prior art, the preparation method is simple and high in efficiency, only water is consumed by the solvent, other high-cost and harmful solvents are not involved, zero pollution emission can be realized, and batch mass production can be realized.
Wherein the mass ratio of the water to the vermiculite can be (10-1000): 1. the mass ratio of water to vermiculite is too low, namely the content of water is too low, which may cause poor peeling effect of the vermiculite and failure in pore formation. Whereas a too high mass ratio, i.e. a too high water content, results in an inefficient stripping process.
In some embodiments, the mechanical agitation may be at a speed of 200rpm/min to 800rpm/min; the ultrasonic crushing power can be 200-1000W, the temperature can be 0-200 ℃, and the time can be 3-12 h. Further preferably, the ultrasonic crushing power is 360W.
The rotation speed of mechanical stirring is too low, transverse shearing force applied to vermiculite is insufficient, the peeling effect of the vermiculite is easy to be poor, and pore forming is impossible; and the stirring speed is too high, the stirring of the solution is unstable, and the vermiculite stripping effect is also unstable. When the power of the ultrasonic wave is too low, a nano pore structure cannot be formed on the vermiculite nano sheet.
In some embodiments, the solid-liquid separation is achieved by centrifugation, and the rotational speed of the centrifugation step may be 1000rpm/min to 10000rpm/min.
It will be appreciated that in other embodiments, the solid-liquid separation may be achieved by standing sedimentation, etc., and that conventional other solid-liquid separation methods may be used in the present invention. When using the sedimentation method, the sedimentation time determines the thickness of the obtained porous vermiculite nano sheets, i.e. the longer the sedimentation time, the fewer the number of layers of porous vermiculite nano sheets in the supernatant.
In some embodiments, the freeze-drying temperature may be-50 ℃ to-10 ℃ and the vacuum may be less than 500Pa.
Freeze-drying is to solidify the suspension at low temperature, and then sublimate the condensed moisture therein under low pressure, thereby achieving sample drying. The sample obtained by freeze drying can maintain the structure and the morphology of the exfoliated vermiculite two-dimensional material, and conventional oven drying and other modes can cause the two-dimensional material to re-agglomerate due to the surface tension of liquid in the drying process.
The embodiment of the invention also provides the porous vermiculite nano sheet prepared by the preparation method. The thickness of the porous vermiculite nano sheet can be 1 nm-20 nm, the diameter can be 100 nm-5 mu m, and the aperture of the nano hole on the porous vermiculite nano sheet can be 5 nm-80 nm.
In a specific preparation process, the final porous vermiculite nano sheet can be controlled to be single-layer (about 1 nm) or multi-layer (greater than 1 nm) by cooperatively controlling the technological parameters of mechanical stirring and ultrasonic crushing.
The embodiment of the invention also provides a water-based zinc ion battery anode, which comprises a zinc anode and a protective layer arranged on the surface of the zinc anode, wherein the protective layer comprises a binder and the porous vermiculite nano sheet.
The porous vermiculite nano sheet provided by the invention has an atomic-level single-layer/few-layer porous structure, can avoid direct contact between zinc metal and electrolyte when being used as a protective layer of a zinc anode, and realizes [ Zn (H) by utilizing strong adsorption of vermiculite on zinc 2 O) 6 ] 2+ And (3) the rapid desolvation of the polymer can inhibit the occurrence of side reactions. Meanwhile, the negative charge of vermiculite and a vertical ion channel constructed by an atomic-level porous nano sheet structure can greatly promote Zn 2+ Reducing interface polarization. In addition, the two-dimensional vermiculite layer can induce the deposited zinc to grow along the plane in a directional manner, so that the dendrite-free zinc cathode is realized, and the performance of the battery is improved. Therefore, compared with non-porous vermiculite, the protective layer prepared from the porous vermiculite nano sheet can realize stable circulation of the battery under high current and keep smaller polarization voltage.
Wherein the thickness of the protective layer can be 500 nm-50 mu m, and the mass ratio of the porous vermiculite nano sheet to the binder can be (1 to 10)20): 1. too thin a protective layer results in limited dendrite inhibition ability and poor protection of the zinc anode, while too thick a protective layer results in interface to Zn 2+ The transmission resistance of the battery is large, the polarization voltage of the battery is large, the energy efficiency is low, and the battery is difficult to stably work under high current.
The binder may be at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), sodium carboxymethyl cellulose (CMC), styrene-butadiene latex (SBR), and perfluorosulfonic acid-based polymer (Nafion).
In some embodiments, the method for preparing the aqueous zinc-ion battery anode comprises the steps of:
mixing the porous vermiculite nano sheets, a binder and a solvent to form slurry;
providing a zinc cathode, coating the slurry on the surface of the zinc cathode, and drying to form a protective layer to obtain the water-based zinc ion battery cathode.
Wherein the solvent may be N-methylpyrrolidone (NMP) or water; the coating method may be spin coating, knife coating, spray coating, or the like.
The technical scheme of the present invention will be explained below with reference to specific examples and comparative examples. It will be appreciated by those skilled in the art that the following examples are for illustrative purposes only and are not to be construed as limiting the invention. The vermiculite raw materials used in the following examples and comparative examples were purchased from Sigma-Aldrich company under the model Z765422 and were 2-3 mm in size. Other non-mentioned materials and equipment are conventional commercial products or are open source.
Example 1
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, simultaneously carrying out mechanical stirring and ultrasonic crushing for 6 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 360W, and the temperature for peeling the vermiculite sheets is 6 ℃, so as to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze-drying the supernatant to obtain porous vermiculite nano sheets, which are marked as PVMT;
(4) Mixing and stirring 28mgPVMT, 8mg PVDF and 2mL NMP to form uniform slurry, spraying the slurry on the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying the zinc sheet at 60 ℃ for 12 hours to obtain the water-based zinc ion battery cathode with the protective layer, and recording the water-based zinc ion battery cathode as PVMT@Zn.
Fig. 1 is a surface atomic force microscope image of a porous vermiculite nano sheet prepared in this example, and it can be seen from the figure that the porous vermiculite nano sheet is a single-layer nano sheet, and the nano sheet has an obvious pore structure (pore diameter is 10-30 nm), and the thickness of the peeled nano sheet is 1-2 nm, and the diameter is about 500nm. Fig. 2 is a cross-sectional scanning electron microscope image of the negative electrode of the aqueous zinc-ion battery prepared in this example, and it can be seen from the figure that the thickness of the protective coating is uniform, about 4.3 μm. Fig. 3 (a) is a contact angle of pure zinc electrode (Bare Zn) with deionized water, the contact angle being 95 °; fig. 3 (b) shows the contact angle between the negative electrode (pvmt@zn) of the aqueous zinc-ion battery prepared in this example and deionized water, wherein the contact angle is 27 °. From the figure, the water-based zinc ion battery cathode modified by the protective layer has good hydrophilicity.
Example 2
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, simultaneously carrying out mechanical stirring and ultrasonic crushing for 9 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 360W, and the temperature for peeling the vermiculite sheets is 6 ℃ to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze drying the supernatant to obtain porous vermiculite nano sheets, which are marked as PVMT;
(4) Mixing and stirring 28mg PVMT, 8mg PVDF and 2mL NMP to form uniform slurry, spraying the slurry onto the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying at 60 ℃ for 12 hours to obtain the water-based zinc ion battery anode with the protective layer.
Example 3
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, simultaneously carrying out mechanical stirring and ultrasonic crushing for 6 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 360W, and the temperature for peeling the vermiculite sheets is 6 ℃, so as to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze drying the supernatant to obtain porous vermiculite nano sheets, which are marked as PVMT;
(4) Mixing and stirring 32mg PVMT, 4mg PVDF and 2mL NMP to form uniform slurry, spraying the slurry on the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying the zinc sheet at 60 ℃ for 12 hours to obtain the water-based zinc ion battery anode with the protective layer.
Example 4
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, simultaneously carrying out mechanical stirring and ultrasonic crushing for 6 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 360W, and the temperature for peeling the vermiculite sheets is 6 ℃, so as to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze drying the supernatant to obtain porous vermiculite nano sheets, which are marked as PVMT;
(4) Mixing 28mg of porous vermiculite nano sheet, 8mg of PTFE and 2mL of deionized water, stirring to form uniform slurry, spraying the slurry onto the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying at 60 ℃ for 12 hours to obtain the water-based zinc ion battery anode with the protective layer.
Example 5
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, simultaneously carrying out mechanical stirring and ultrasonic crushing for 6 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 360W, and the temperature for peeling the vermiculite sheets is 6 ℃, so as to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze drying the supernatant to obtain porous vermiculite nano sheets, which are marked as PVMT;
(4) Mixing and stirring 28mg PVMT, 8mg Nafion and 2mL deionized water to form uniform slurry, spraying the slurry onto the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying at 60 ℃ for 12 hours to obtain the water-based zinc ion battery cathode with the protective layer.
Comparative example 1
The embodiment provides a negative electrode of a water-based zinc ion battery, and the preparation method comprises the following steps:
(1) Weighing 500mg of vermiculite and adding the vermiculite into 20mL of deionized water, and simultaneously carrying out mechanical stirring and ultrasonic crushing for 3 hours, wherein the mechanical stirring rotating speed is 500rpm/min, the using power of an ultrasonic cell grinder is 120W, and the temperature for peeling the vermiculite sheets is 6 ℃ to obtain a suspension containing the vermiculite sheets;
(2) Carrying out solid-liquid separation on the suspension at 2000rpm/min to obtain supernatant;
(3) Freeze-drying the supernatant to obtain non-porous vermiculite, which is marked as NVMT;
(4) Mixing 28mgNVMT, 8mg PVDF and 2mL NMP, stirring to form uniform slurry, spraying the slurry on the surface of a zinc sheet, transferring the zinc sheet into a vacuum oven, and drying at 60 ℃ for 12 hours to obtain the water-based zinc ion battery cathode with the protective layer, which is marked as NVMT@Zn.
FIG. 4 is a surface atomic force microscope image of a non-porous vermiculite nano sheet prepared in this example, from which it can be seen that the non-porous vermiculite is a near monolayer nano sheet, but the nano sheet has a non-porous structure, the thickness of the exfoliated nano sheet is 1-2 nm, and the diameter is about 400nm. It is stated that the process parameters of mechanical agitation and ultrasonic disruption will synergistically affect the structure of the final product, and that if the ultrasonic power is too low and/or the time is too short, no porous nanosheet structure can be obtained.
Performance testing
1. Both the anode and the cathode of the battery adopt the water system zinc ion battery cathode (PVMT@Zn) prepared in the embodiment 1, a glass fiber filter membrane is a membrane, and 2mol/L ZnSO is adopted 4 And (3) using the solution as electrolyte to assemble a 2032 type button cell to obtain the PVMT@Zn|PVMT@Zn symmetrical cell. Similarly, the NVMT@Zn prepared in the comparative example is used as a positive electrode and a negative electrode of the battery, and the NVMT@Zn|NVMT@Zn symmetrical battery is prepared; and (3) adopting a pure zinc cathode as a positive electrode and a negative electrode of the battery to prepare the Bare Zn symmetric battery. The symmetrical battery is subjected to a current density of 10mA/cm at 25 DEG C 2 The charge-discharge capacity is 1mAh/cm 2 And (5) carrying out cycle performance test under the condition.
2. The aqueous zinc ion battery anode (PVMT@Zn) prepared in example 1 was used as a battery anode, mnO 2 As the positive electrode of the battery, a glass fiber filter membrane is a membrane, and 2mol/L ZnSO is adopted 4 And 0.1mol/LMnSO 4 As the electrolyte, the mixed solution of (a) is used, assembling 2032 type button cell to obtain PVMT@Zn||MnO 2 And (3) a full battery. The whole cell was subjected to a current density of 616mA/g (vs. MnO at 25 DEG C 2 ) Under the condition, the specific capacity of the battery was tested. In the same way, a pure zinc cathode is adopted as a battery cathode to prepare Bare Zn MnO 2 And (3) a full battery.
Fig. 5 is an electrochemical impedance curve of pvmt@zn||pvmt@zn, nvmt@zn||nvmt@zn and Bare zn||bare Zn symmetrical cells in an initial state. From the figure, it can be seen that the magnitudes of the three cell interface charge transfer impedances are ordered as: PVMT@Zn||PVMT@Zn < NVMT@Zn|NVMT@Zn < pore Zn|pore Zn, which indicates that the porous vermiculite has faster ion transmission and smaller interface polarization than the non-porous vermiculite.
FIG. 6 is a PVMT@Zn||PVMT@Zn symmetric battery and a Bare Zn|bare Zn symmetric battery at 10mA/cm 2 、1mAh/cm 2 Charge-discharge cycle curve under test conditions. From the graph, it can be seen that the polarization voltage of the Bare Zn symmetric battery is constantly increased, and the battery is subjected to 'saw-tooth fluctuation' during 200h of circulation, and finally the battery is short-circuited during 300h of circulation. And PVMT@Zn pairThe battery can stably circulate for more than 800 hours, and the polarization voltage is obviously smaller than that of a pure zinc symmetrical battery.
The PVMT@Zn|PVMT@Zn symmetric battery and the Bare Zn|bare Zn symmetric battery after 40h of circulation are selected for disassembly, scanning electron microscope characterization and analysis are carried out on the surfaces, and (a) of FIG. 7 is that the PVMT@Zn|PVMT@Zn symmetric battery obtained in the embodiment 1 of the invention is 10mA/cm 2 、1mAh/cm 2 Surface scanning electron microscopy image of 40h of cycle under test condition, fig. 7 (b) is a surface scanning electron microscopy image of the pvmt@zn negative electrode surface after removing the protective layer in fig. 7 (a), and fig. 7 (c) is a Bare Zn symmetric battery at 10mA/cm 2 、1mAh/cm 2 Surface scanning electron microscope images after 40h of circulation under test conditions. From fig. 7 (a), it can be seen that the protective layer in the pvmt@zn|pvmt@zn symmetrical battery is complete and has no obvious damage, and no dendrite is generated on the surface of the negative electrode of the water-based zinc ion battery with the protective layer. After removal of the protective layer by powerful ultrasound, it can be seen from fig. 7 (b) that Zn deposited under the protective layer has planar preferential orientation, while from fig. 7 (c) it can be seen that the surface after cycling of the unprotected pure zinc negative electrode is distributed with irregularly oriented dendrites. This demonstrates that the protective layer containing porous vermiculite nanoplatelets can still induce zinc deposition behavior under high current, inhibiting dendrite growth.
FIG. 8 is a graph showing that PVMT@Zn||PVMT@Zn and fire Zn||fire Zn symmetric cells were at 50mA/cm 2 、1mAh/cm 2 Charge-discharge cycle curve under test conditions. From the graph, it can be seen that the polarization voltage of the Bare Zn symmetric battery under the ultra-high current density is close to 1V, and the battery is short-circuited after being cycled for less than 10 hours. The polarization voltage of the symmetric battery which is reversely protected by the porous vermiculite nano sheet coating is only about 0.25V after being stabilized, and the symmetric battery can be stably circulated for 300 hours.
FIG. 9 is a diagram of the present embodiment PVMT@Zn||MnO prepared by the method 2 Full cell Bare Zn MnO 2 Coulombic efficiency curve of full cell at 616mA/g test conditions. As can be seen from the figures of the drawing, PVMT@Zn||MnO 2 The coulombic efficiency of the whole cell is higher than that of Bare Zn MnO 2 Full cell, and less fluctuating and more stable during cycling. FIG. 10 shows the embodiment PVMT@Zn||MnO prepared by the method 2 Full cell and Bare Zn||MnO 2 Cycling curve of full cell at 616mA/g test conditions. As can be seen from the figure, bare Zn MnO 2 The capacity of the full cell drops rapidly to 50mAh/g after 500 cycles, while the capacity of the full cell based on pvmt@zn remains 123mAh/g. It can be seen that the protection layer containing porous vermiculite nano sheets has obvious improvement on the performance of the full battery.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. The preparation method of the porous vermiculite nano sheet is characterized by comprising the following steps:
dispersing vermiculite in water, and then simultaneously carrying out mechanical stirring and ultrasonic crushing to obtain a suspension containing vermiculite flakes;
carrying out solid-liquid separation on the suspension to obtain a supernatant;
and freeze-drying the supernatant to obtain the porous vermiculite nano sheet.
2. The method of claim 1, wherein the mass ratio of water to vermiculite is (10-1000): 1.
3. the method according to claim 1, wherein the rotation speed of the mechanical stirring is 200rpm/min to 800rpm/min.
4. The method according to claim 1, wherein the ultrasonic crushing power is 200W to 1000W, the temperature is 0 ℃ to 200 ℃ and the time is 3h to 12h.
5. The method according to claim 1, wherein the suspension is subjected to solid-liquid separation by centrifugation at a rotational speed of 1000rpm/min to 10000rpm/min.
6. A porous vermiculite nano sheet prepared by the method of any one of claims 1 to 5.
7. The porous vermiculite nanoplatelets of claim 6, wherein the porous vermiculite nanoplatelets have a thickness of 1nm to 20nm and a diameter of 100nm to 5 μm.
8. An aqueous zinc ion battery cathode, comprising a zinc cathode and a protective layer arranged on the surface of the zinc cathode, wherein the protective layer comprises a binder and the porous vermiculite nano sheet as defined in any one of claims 6-7.
9. The aqueous zinc-ion battery anode according to claim 8, wherein the protective layer has a thickness of 500nm to 50 μm.
10. The negative electrode of the water-based zinc-ion battery according to claim 8, wherein the mass ratio of the porous vermiculite nano sheet to the binder is (1-20): 1.
CN202310487643.2A 2023-04-28 2023-04-28 Preparation method of porous vermiculite nano sheet, porous vermiculite nano sheet and negative electrode of water system zinc ion battery Pending CN116443887A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109980302A (en) * 2019-04-29 2019-07-05 中南大学 A kind of water system Zinc ion battery colloidal electrolyte and its preparation method and application
CN111233509A (en) * 2020-01-17 2020-06-05 西南科技大学 Vermiculite nanosheet and preparation method thereof
CN111701574A (en) * 2020-05-21 2020-09-25 阿拉尔市中泰纺织科技有限公司 Treatment of Cr-containing material with expanded vermiculite3+Method for treating waste water
CN111934008A (en) * 2020-08-12 2020-11-13 郑州大学 Layered composite solid electrolyte and preparation method and application thereof
KR20220096048A (en) * 2020-12-30 2022-07-07 연세대학교 산학협력단 Polymer-clay nanocomposite electrolyte for secondary battery and method for preparing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109980302A (en) * 2019-04-29 2019-07-05 中南大学 A kind of water system Zinc ion battery colloidal electrolyte and its preparation method and application
CN111233509A (en) * 2020-01-17 2020-06-05 西南科技大学 Vermiculite nanosheet and preparation method thereof
CN111701574A (en) * 2020-05-21 2020-09-25 阿拉尔市中泰纺织科技有限公司 Treatment of Cr-containing material with expanded vermiculite3+Method for treating waste water
CN111934008A (en) * 2020-08-12 2020-11-13 郑州大学 Layered composite solid electrolyte and preparation method and application thereof
KR20220096048A (en) * 2020-12-30 2022-07-07 연세대학교 산학협력단 Polymer-clay nanocomposite electrolyte for secondary battery and method for preparing the same

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