Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
The following description of the various embodiments refers to the accompanying drawings, which are included to illustrate specific embodiments in which the application may be practiced. Directional phrases used in this application, such as, for example, "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "side," and the like, refer only to the orientation of the appended drawings and are, therefore, used herein for better and clearer illustration and understanding of the application and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the application.
Moreover, the ordinal numbers used herein for the components, such as "first," "second," etc., are used merely to distinguish between the objects described, and do not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
Referring to fig. 1, an embodiment of the present disclosure provides a current collector 100. The current collector 100 includes a base body 10 and a body portion 30. The main body part 30 is arranged on the surface of the substrate 10, the main body part 30 at least comprises a first layered structure 31 and a second layered structure 33, the first layered structure 31 comprises a plurality of first holes 311, the second layered structure 33 comprises a plurality of second holes 331, the average pore diameter of the second holes 331 is larger than the average pore diameter of the first holes 311, the first holes 311 are communicated with the second holes 331, and the main body part is sequentially stacked on the substrate 10, the first layered structure 31 and the second layered structure 33.
There are currently no two possible approaches to the negative electrode design: (1) Completely replacing copper as a current collector, and (2) coating a modification layer on the copper. Among them, the complete replacement of copper as a current collector is mostly achieved by preparing a 3D multifunctional current collector or a composite current collector. The two methods for realizing the non-negative electrode design can slow down the volume change or improve the specific energy to a certain extent, but the problem of dendrite is still unsolved.
In the current collector 100 of the present application, the constructed current collector 100 at least includes the first layered structure 31 and the second layered structure 33, and an average pore diameter of the second pores 331 of the second layered structure 33 is greater than an average pore diameter of the first pores 311 of the first layered structure 31, so that the current collector 100 has an advantage of ordered structure; and the substrate 10, the first layered structure 31 and the second layered structure 33 are sequentially stacked, so that the current collector 100 has the advantages of a huge reaction interface and gradient porosity distribution, and active metal ions are deposited from pores with large pore diameters to pores with small pore diameters in the charging process, so that the formation of metal dendrites is effectively inhibited, and the safety performance, the rate capability and the cycle performance of the battery are improved.
Referring to fig. 2, the present application further provides a battery 1000, where the battery 1000 includes a positive electrode sheet 300, a separator 200, a current collector 100 according to any embodiment of the present application, and an electrolyte. After the current collector 100, the positive electrode sheet 300, and the separator 200 are assembled, an electrolyte is injected.
The current collector 100 of the embodiment of the application is applied to the battery 1000, wherein the battery 1000 includes a non-negative lithium battery and a non-negative sodium battery, the current collector 100 replaces a negative current collector and a negative active material in a traditional battery, the current collector 100, a positive pole piece 300 and a diaphragm 200 are assembled into the battery 1000, and the non-negative lithium battery or the sodium battery is prepared, so that the volume of a battery core in the battery 1000 can be effectively reduced, and the energy density of the battery 1000 is improved.
The base 10 includes a first surface 11 and a second surface 13 opposite to each other, and the main body 30 is disposed on the first surface 11 and/or the second surface 13. For example, the main body 30 is provided on the first surface 11; alternatively, the main body 30 is provided on the second surface 13; alternatively, the body 30 is provided on the first surface 11 and the second surface 13.
In the embodiment of the present application, the base body 10 is composed of a tungsten foil, and the base body 10 is composed of a tungsten foil, so that the current collector 100 can have high conductivity.
In one embodiment, the main body 30 is disposed on the first side 11 of the substrate 10, the main body 30 at least includes a first layered structure 31 and a second layered structure 33 in a direction from the second side 13 to the first side 11, the first layered structure 31 includes a plurality of first holes 311, the second layered structure 33 includes a plurality of second holes 331, an average hole diameter of the second holes 331 is larger than an average hole diameter of the first holes 311, the first holes 311 are communicated with the second holes 331, and the substrate 10, the first layered structure 31 and the second layered structure 33 are sequentially stacked. Therefore, the current collector 100 has a reaction interface with an ordered structure and a huge reaction interface, and the problem of volume expansion in the battery charging and discharging process can be effectively avoided.
In another embodiment, the body portions 30 are disposed on the first face 11 and the second face 13 of the base 10, and the body portions 30 on the first face 11 and the body portions 30 on the second face 13 are symmetrical with respect to the base 10. The provision of the body 30 on the first and second surfaces 11 and 13 allows the reaction interface of the current collector 100 to be larger, reduces the local current density, guides the lithium/sodium ion deposition, prevents local overheating, and improves the safety of the battery 1000, compared to the provision of the body 30 on the first or second surface 11 or 13 of the substrate 10.
The current collector 100 will be described in detail with reference to the case where the main body 30 is provided on both the first surface 11 and the second surface 13.
In an embodiment of the present application, the material of which body portion 30 is made comprises a MOFs material comprising MOF-5 (Zn) 4 O(BDC) 3 ·(DMF) 8 (C 6 H 5 Cl))、MOF-69C(Zn 3 (OH) 2 (1,4-BDC) 2 ·(DEF) 2 )、MOF-74(Zn 2 (DHBDC)(DMF) 2 ·(H 2 O) 2 )、ZIF-8(Zn(MeIM) 2 ·(DMF)·(H 2 O) 3 )、MIL-100(Fe)-Fe 3 O(H 2 O) 2 F·{C 6 H 3 (CO 2 ) 3 } 2 ·14.5H 2 O、MOF-199-[Cu 3 (BTC) 2 (H 2 O) 3 ]、NOTT-300-[Al 2 (OH) 2 (C 16 O 8 H 6 )](H 2 O) 6 At least one of (a).
The three-dimensional carbon current collector has the lithium-philic characteristic, and in the circulation process, the metal lithium is in poor contact with the three-dimensional carbon current collector and is easy to fall off to form dead lithium. In the present application, the MOFs material used for the current collector 100 is formed by coordinating a metal center and an organic ligand, and the metal center can be converted into a monoatomic atom, a metal particle, a metal oxide, or metal nitrogen or a metal carbide in a high-temperature carbonization process. And the organic ligand is converted into a heteroatom-doped porous carbon material in the high-temperature carbonization process, and the metal and the heteroatom can be used as nucleophilic sites to guide lithium/sodium metal ions to deposit.
Referring to fig. 1, the main body 30 may include a first layered structure 31 and a second layered structure 33. Alternatively, the body portion 30 may include a first layered structure 31, a second layered structure 33, and a third layered structure 35, the base 10, the first layered structure 31, the second layered structure 33, and the third layered structure 35 are sequentially stacked, and the third layered structure 35 includes a plurality of third holes 351, an average pore diameter of the third holes 351 is larger than an average pore diameter of the second holes 331, an average pore diameter of the second holes 331 is larger than an average pore diameter of the first holes 311, and the first holes 311, the second holes 331, and the third holes 351 are all communicated. Therefore, the reaction interface of the current collector 100 is larger, and the problem of volume expansion in the charging and discharging process of the battery can be effectively avoided. The current collector 100 will be described in detail in the present application, taking as an example that the main body portion 30 includes the first layered structure 31, the second layered structure 33, and the third layered structure 35.
Specifically, the first hole 311 includes a first sub-hole 3111 and a plurality of first openings 3113 provided around the first sub-hole 3111, and each of the plurality of first openings 3113 communicates with the first sub-hole 3111. The second hole 331 includes a second sub-hole 3311 and a plurality of second openings 3313 defined around the second sub-hole 3311, and the plurality of second openings 3313 are all communicated with the second sub-hole 3311. The third hole 351 includes a third sub-hole 3511 and a plurality of third openings 3513 provided around the third sub-hole 3511, and each of the plurality of third openings 3513 communicates with the third sub-hole 3511. The first sub-hole 3111 and the second sub-hole 3311 are communicated through the first opening 3113 and the second opening 3313, and the second sub-hole 3311 and the third sub-hole 3511 are communicated through the second opening 3313 and the third opening 3513, so that the current collector 100 has a three-dimensional ordered intercommunicating structure, and uniformity of electrochemical reaction is ensured.
Further, the first sub-aperture 3111, the second sub-aperture 3311, and the third sub-aperture 3511 may each be a sphere-like cavity.
It should be noted that, in the layer structure farthest from the substrate 10, such as the third layer structure 35, each third sub-hole 3511 on the side far from the substrate 10 is provided with a third opening 3513 communicated with the third sub-hole 3511, so that active metal ions can enter the current collector 100 from the plurality of third openings 3513 on the side farthest from the substrate 10, and during the charging process, the deposition from the third sub-hole 3511 with a large pore size to the first sub-hole 3111 with a small pore size is completed.
In the embodiment of the present application, the pore diameter of the first sub-pore 3111 is in the range of [10nm,100nm ] in the direction away from the surface of the substrate 10. The pore diameter of the second sub-pores 3311 is in the range of [100nm,300nm ]. The pore diameter of the third sub-pore 3511 is in the range of [300nm,1000nm ].
The plurality of first sub-holes 3111 are uniformly distributed, the pore diameters of the plurality of first sub-holes 3111 are the same, the pore diameter of each first sub-hole 3111 may be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm, and the pore diameter of the first sub-hole 3111 may be any pore diameter satisfying [10nm,100nm ], which is not listed here.
Wherein each first opening 3113 is circular, and the aperture of each first opening 3113 is smaller than that of the first sub-hole 3111. The aperture sizes of the plurality of first openings 3113 in the first layered structure 31 may be the same or may be different.
The plurality of second sub-holes 3311 are uniformly distributed, and the plurality of second sub-holes 3311 have the same diameter, and the diameter of the second sub-holes 3311 is larger than that of the first sub-holes 3111. The pore diameter of each second sub-pore 3311 may be 100nm, 130nm, 150nm, 180nm, 200nm, 220nm, 240nm, 270nm, 290nm, or 300nm, and the pore diameters of the second sub-pores 3311 may be selected to satisfy [100nm,300nm ], which is not listed herein.
Each of the second openings 3313 is circular, and the diameter of each of the second openings 3313 is smaller than the diameter of the second sub-holes 3311. The aperture sizes of the second openings 3313 in the second layer structure 33 may be the same or may be different.
The plurality of third sub-holes 3511 are uniformly distributed, the diameters of the plurality of third sub-holes 3511 are the same, and the diameter of the third sub-hole 3511 is larger than that of the second sub-holes 3311. The pore diameter of each third sub-pore 3511 may be 300nm, 400nm, 470nm, 550nm, 610nm, 690nm, 730nm, 810nm, 900nm, or 1000nm, and the pore diameters of the third sub-pores 3511 may satisfy [300nm,1000nm ], which is not listed herein.
Each third opening 3513 is circular, and the diameter of each third opening 3513 is smaller than that of the third sub-hole 3511. The pore sizes of the plurality of third openings 3513 in the third layered structure 35 may be the same or may be different.
That is, in the current collector 100, the first sub-hole 3111, the second sub-hole 3311 and the third sub-hole 3511, which have pore sizes gradually increasing, are sequentially distributed in a direction away from the substrate 10, so that the current collector 100 has a characteristic of unique gradient porosity distribution, thereby being capable of reducing a lithium ion/sodium ion concentration gradient in the electrolyte in a region close to the diaphragm, slowing down a lithium/sodium precipitation process, and improving the safety performance of the battery 1000.
In the embodiment of the present application, the layer in which the first sub-holes 3111 with the same aperture are located includes two first sub-layers arranged in parallel, and the first sub-holes 3111 in the two first sub-layers have the same aperture. The layer in which the second sub-holes 3311 having the same aperture are located includes two second sub-layers arranged in parallel, and the apertures of the second sub-holes 3311 in the two second sub-layers are the same. The layer in which the third sub-holes 3511 with the same aperture are located includes two third sub-layers arranged in parallel, and the apertures of the third sub-holes 3511 in the two third sub-layers are the same.
In other embodiments, the layer where the first sub-hole 3111 is located may include three or more first sub-layers, the layer where the second sub-hole 3311 is located may include three or more second sub-layers, and the layer where the third sub-hole 3511 is located may include three or more third sub-layers, where the layers where the sub-holes (including the first sub-hole 3111, the second sub-hole 3311, and the third sub-hole 3511) with the same pore diameter are located have multiple sub-layers, so that the reaction interface of the reaction layer may be effectively increased, thereby reducing the local current density in the battery, guiding the lithium/sodium ions to be uniformly deposited, preventing local overheating, and improving the safety of the battery.
In summary, in the current collector 100 of the present application, the pore diameter of the sub-pores close to the substrate 10 (including the first sub-pore 3111, the second sub-pore 3311, and the third sub-pore 3511) is the smallest, and the pore diameter of the sub-pores far from the substrate 10 is the largest, so that the current collector 100 has a three-dimensional ordered interconnected structure with unique gradient porosity distribution, and the current collector 100 with ordered structure can ensure the uniformity of the electrochemical reaction; the huge reaction interface can reduce the local current density, guide the lithium/sodium ions to be uniformly deposited, prevent local overheating and improve the safety; the unique gradient porosity reduces the concentration gradient of lithium ions/sodium ions in the electrolyte in the area close to the diaphragm, slows down the process of separating lithium/sodium and improves the safety performance of the battery cell.
Referring to fig. 3 and 4, an embodiment of the present application further provides a method for manufacturing a current collector. The current collector manufacturing method includes the following steps S301 to S304:
s301: forming a silica opal template on the surface of the substrate 10, wherein the silica opal template comprises a plurality of layers of silicon dioxide, the particle sizes of the silicon dioxide in different layers are different, and the particle sizes of the silicon dioxide in different layers are gradually increased along the direction away from the surface of the substrate 10;
s302: filling a silica opal template with MOFs material solution;
s303: carrying out high-temperature carbonization treatment on the silica opal template filled with the MOFs material solution;
s304: removing the silicon dioxide in the silica opal template after the high temperature carbonization treatment to obtain the current collector 100 according to any embodiment of the present disclosure.
The current collector 100 comprises a substrate 10 and a main body 30, the main body 30 is arranged on the surface of the substrate 10, the main body 30 at least comprises a first layered structure 31 and a second layered structure 33, the first layered structure 31 comprises a plurality of first holes 311, the second layered structure 33 comprises a plurality of second holes 331, the average pore diameter of the second holes 331 is larger than that of the first holes 311, the first holes 311 are communicated with the second holes 331, and the substrate 10, the first layered structure 31 and the second layered structure 33 are sequentially stacked.
In step S301, a silica opal template may be formed on one side surface (e.g., the first surface 11 or the second surface 13) of the substrate 10, or both side surfaces of the substrate 10, and the present application will be described in detail with reference to the case where the silica opal template is formed on both side surfaces (e.g., the first surface 11 and the second surface 13) of the substrate 10. Wherein, the silica opal template comprises three layers of silicon dioxide, and the grain diameters of the three layers of silicon dioxide are respectively [10nm,100nm ], [100nm,300nm ], [300nm and 1000nm ] in the direction far away from the surface of the substrate 10. That is, three layers of silica are formed on the first surface 11 of the substrate 10, and three layers of silica are formed on the second surface 13 of the substrate 10, with the silica having the smallest particle size near the substrate 10 and the silica having the largest particle size far from the substrate 10 to form the structurally-ordered gradient porosity current collector 100.
Wherein, the silicon dioxide with the grain diameter value range of [10nm,100nm ] comprises two first sub-layers which are arranged in parallel, and the grain diameters of the silicon dioxide in the two first sub-layers are the same. The silicon dioxide with the value range of [100nm and 300nm ] comprises two second sub-layers arranged in parallel, and the particle sizes of the silicon dioxide in the two second sub-layers are the same. The silicon dioxide with the grain diameter value range of [300nm,1000nm ] comprises two third sub-layers which are arranged in parallel, and the grain diameters of the silicon dioxide in the two third sub-layers are the same.
In one possible embodiment, step S302: the implementation method for filling the silica opal template with the MOFs material solution can be as follows: the MOFs material solution is filled into the gaps of the silica opal template through capillary action.
Specifically, in the present application, a MOFs material solution made of a Metal Organic Framework (MOFs) material is filled in a gap of a silica opal template to uniformly cover the MOFs material in the MOFs material solution on the silica, wherein in a layer of silica farthest from the substrate 10, the MOFs material solution does not completely cover the silica, so that after the silica opal template filled with the MOFs material solution is subjected to a high temperature carbonization treatment, third sub-holes 3511 formed in the layer of silica farthest from the substrate 10 are all formed with third openings 3513, so that active Metal ions can conveniently enter the current collector 100 from the third openings 3513.
The MOFs material solution comprises MOFs materials and a first solvent mixed with the MOFs materials. Preferably, the MOFs material comprises MOF-5 (Zn) 4 O(BDC) 3 ·(DMF) 8 (C 6 H 5 Cl))、MOF-69C(Zn 3 (OH) 2 (1,4-BDC) 2 ·(DEF) 2 )、MOF-74(Zn 2 (DHBDC)(DMF) 2 ·(H 2 O) 2 )、ZIF-8(Zn(MeIM) 2 ·(DMF)·(H 2 O) 3 )、MIL-100(Fe)-Fe 3 O(H 2 O) 2 F·{C 6 H 3 (CO 2 ) 3 } 2 ·14.5H 2 O、MOF-199-[Cu 3 (BTC) 2 (H 2 O) 3 ]、NOTT-300-[Al 2 (OH) 2 (C 16 O 8 H 6 )](H 2 O) 6 At least one of (a). The first solvent comprises one of water, N-dimethylformamide, alcohol and acetone.
The three-dimensional carbon current collector has the lithium-philic characteristic, and in the circulation process, the metal lithium is in poor contact with the three-dimensional carbon current collector and is easy to fall off to form dead lithium. In the present application, the MOFs material adopted by the current collector 100 is formed by coordinating a metal center and an organic ligand, and the metal center can be converted into a monoatomic metal particle, a metal oxide, or a metal nitride or a metal carbide in a high-temperature carbonization process. And the organic ligand is converted into a heteroatom-doped porous carbon material in the high-temperature carbonization process, and the metal and the heteroatom can be used as nucleophilic sites to guide lithium/sodium metal ions to deposit.
And S303, performing high-temperature carbonization treatment on the silica opal template filled with the MOFs material solution, wherein the temperature of the high-temperature carbonization treatment is over 1000 ℃, so as to primarily remove the human silicon oxide in the silica opal template.
Step S304: the implementation method for removing the silicon dioxide in the silica opal template after the high-temperature carbonization treatment to obtain the current collector 100 may be: and removing the silica opal template subjected to high-temperature carbonization treatment by using hydrofluoric acid to obtain the current collector 100.
After the silicon protein template filled with the MOFs material solution is carbonized at high temperature, the silicon dioxide in the silicon protein template is washed away by hydrofluoric acid, and the first sub-hole 3111, the second sub-hole 3311 and the third sub-hole 3511 (wherein the particle size of the silicon dioxide in the corresponding sub-layer is equal to the pore size of the sub-hole in the corresponding sub-layer) are formed at the positions where the silicon dioxide in the different sub-layers abut against each other, so that the first opening 3113, the second opening 3313 and the third opening 3513 are formed, and the current collector 100 comprising the substrate 10 and the substrate 30 is manufactured, wherein the current collector 100 has the characteristics of ordered three-dimensional structure, huge reaction interface and gradient porosity distribution, and due to the action of the MOFs material, the current collector 100 has the advantages of high conductivity, nucleophilic nucleation sites and the like, so that the formation of metal dendrites can be inhibited, and the safety performance, rate performance and cycle performance of the battery 1000 are improved.
Referring to fig. 2 and 5, a method for manufacturing a battery is also provided in the present embodiment. The battery preparation method comprises the following steps S501-S503:
s501: the positive electrode active material, the conductive agent and the binder are mixed according to the proportion of (90-95): (1-4): (3-7) and a second solvent are uniformly mixed and stirred to obtain slurry;
s502: coating the slurry on an aluminum foil, and drying and cold-pressing to obtain a positive pole piece 300;
s503: after encapsulating the positive electrode sheet 300, the current collector 100 and the separator 200 manufactured by the current collector manufacturing method according to any embodiment of the present application, an electrolyte is injected to manufacture the battery 1000.
In step S501, the positive electrode active material is preferably at least one selected from lithium iron phosphate, lithium cobaltate, lithium nickel cobalt manganese oxide, sodium copper iron manganese oxide, sodium nickel manganese oxide titanate, sodium nickel manganese iron copper oxide, sodium iron phosphate, sodium vanadium fluorophosphate, sodium vanadium phosphate, ferric Prussian blue, and manganic Prussian blue. The second solvent comprises one of water, N-methyl pyrrolidone, dimethyl amide or dimethyl acetamide. The positive electrode active material, the conductive agent, and the binder are mixed with the second solvent at a ratio of 92 3.
In step S503, the separator 200 is preferably at least one selected from lithium iron phosphate, lithium cobaltate, lithium nickel cobalt manganese oxide, sodium copper iron manganese oxide, sodium nickel manganese titanate, sodium nickel manganese iron copper oxide, sodium iron phosphate, sodium vanadium fluorophosphate, sodium vanadium phosphate, ferric iron based prussian blue, and manganous iron based prussian blue. The electrolyte is prepared from metal salt, a third solvent and an additive, wherein the metal salt comprises LiPF 6 、LiClO 4 、LiAsF 6 、LiBF 4 、NaPF 6 、NaClO 4 、NaAsF 6 、NaBF 4 To (3) is provided. The third solvent includes at least one of Ethylene Carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC), and Propylene Carbonate (PC). The additive comprises at least one of Vinylene Carbonate (VC), fluoroethylene carbonate (FEC) and Vinyl Ethylene Carbonate (VEC).
In order to better understand the technical solutions provided by the present application, the following specific examples respectively illustrate the specific processes of the current collector 100 and the battery manufactured by the method for manufacturing the battery, which are provided by the above examples of the present application.
The first embodiment is as follows:
step 1: the preparation method comprises the steps of self-assembling three kinds of silicon dioxide with different particle sizes on the surfaces of two sides of a tungsten foil layer by layer to prepare a silica opal template, wherein the particle sizes are 100nm, 200nm and 300nm from small to large in sequence, injecting an MOF-5 material solution into gaps of the silica opal template, carbonizing at high temperature, and then washing off the silicon dioxide by hydrofluoric acid to obtain a current collector with gradient porosity distribution.
Step 2: mixing and stirring the sodium nickel-iron manganate, the conductive agent and the binder with a second solvent uniformly according to the proportion of 92.
And step 3: and (3) assembling the current collector prepared in the step (1) and the positive pole piece prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-pole sodium-ion battery.
And 4, step 4: step 3, after the assembled cathode-free sodium ion battery is subjected to chemical composition and partial capacity, constant current charge and discharge tests are carried out at 25 ℃, and the charge and discharge tests comprise the following steps: charging at constant current of 1C multiplying power to 4V, charging at constant voltage of 4V to 0.05C, stopping charging, standing for 5min, discharging at constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Example two:
step 1: self-assembling three kinds of silicon dioxide with different particle sizes on the two side surfaces of the tungsten foil layer by layer to prepare a silica opal template, wherein the particle sizes are 50nm, 200nm and 350nm from small to large in sequence, injecting a solution of an MOF-5 material into gaps of the silica opal template, carbonizing at high temperature, and washing away the silicon dioxide by hydrofluoric acid to obtain the current collector with gradient porosity distribution.
Step 2: mixing and stirring the sodium nickel manganese oxide, the conductive agent and the binder with a second solvent uniformly according to a ratio of 92 to 3 to obtain slurry, coating the slurry on an aluminum foil, drying, and performing cold pressing to obtain the positive pole piece.
And step 3: and (3) assembling the current collector prepared in the step (1) and the positive pole piece prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-pole sodium-ion battery.
And 4, step 4: after the battery assembled in the step 3 is subjected to chemical composition and partial capacity, constant-current charge and discharge testing is carried out at 25 ℃, and the charge and discharge testing step comprises the following steps: charging with constant current of 1C multiplying power to 4V, charging with constant voltage of 4V to 0.05C, standing for 5min, discharging with constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Example three:
step 1: the preparation method comprises the steps of self-assembling three kinds of silicon dioxide with different particle sizes on the surfaces of two sides of a tungsten foil layer by layer to prepare a silica opal template, wherein the particle sizes are 50nm, 300nm and 1000nm from small to large in sequence, injecting a solution of an MOF-5 material into gaps of the silica opal template, carbonizing at a high temperature, and then washing off the silicon dioxide by hydrofluoric acid to obtain a current collector with gradient porosity distribution.
Step 2: mixing and stirring the sodium nickel manganese oxide, the conductive agent and the binder with a second solvent uniformly according to a ratio of 92 to 3 to obtain slurry, coating the slurry on an aluminum foil, drying, and performing cold pressing to obtain the positive pole piece.
And step 3: and (3) assembling the current collector prepared in the step (1) and the positive pole piece prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-pole sodium-ion battery.
And 4, step 4: after the battery assembled in the step 3 is subjected to chemical composition and partial capacity, constant-current charge and discharge testing is carried out at 25 ℃, and the charge and discharge testing step comprises the following steps: charging with constant current of 1C multiplying power to 4V, charging with constant voltage of 4V to 0.05C, standing for 5min, discharging with constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: and 2.0mAh/cm < 2 > is deposited at the current density of 1mA/cm < 2 >, the mixture is stood for 10min, and then the mixture is charged to 1.0V at the current density of 1mA/cm < 2 >, and the coulomb efficiency and the polarization voltage of sodium metal on different current collectors can be obtained by taking the cycle process.
Example four:
step 1: the method comprises the steps of self-assembling three types of silicon dioxide with different particle sizes layer by layer to prepare a silica opal template, wherein the particle sizes are 100nm, 200nm and 300nm from small to large in sequence, injecting a solution of an MOF-199 material into gaps of the silica opal template, carbonizing at high temperature, and washing away the silicon dioxide by hydrofluoric acid to obtain a current collector with gradient porosity distribution.
Step 2: mixing and stirring the sodium nickel-iron manganate, the conductive agent and the binder with a second solvent uniformly according to the proportion of 92.
And step 3: and (3) assembling the current collector prepared in the step (1) and the positive pole piece prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-pole sodium-ion battery.
And 4, step 4: after the battery assembled in the step 3 is subjected to chemical composition and partial capacity, constant-current charge and discharge testing is carried out at 25 ℃, and the charge and discharge testing step comprises the following steps: charging with constant current of 1C multiplying power to 4V, charging with constant voltage of 4V to 0.05C, standing for 5min, discharging with constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Example five:
step 1: self-assembling three types of silicon dioxide with different particle sizes layer by layer to prepare a silica opal template, wherein the particle sizes are 100nm, 200nm and 300nm from small to large in sequence, injecting a solution of a NOT-300 material into the gap of the silica opal template, carbonizing at high temperature, and washing away the silicon dioxide by hydrofluoric acid to obtain a current collector.
Step 2: mixing and stirring the sodium nickel manganese oxide, the conductive agent and the binder with a second solvent uniformly according to a ratio of 92 to 3 to obtain slurry, coating the slurry on an aluminum foil, drying, and performing cold pressing to obtain the positive pole piece.
And 3, step 3: and (3) assembling the current collector prepared in the step (1) and the positive pole piece prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-pole sodium-ion battery.
And 4, step 4: after the battery assembled in the step 3 is subjected to chemical composition and partial capacity, constant-current charge and discharge testing is carried out at 25 ℃, and the charge and discharge testing step comprises the following steps: charging at constant current of 1C multiplying power to 4V, charging at constant voltage of 4V to 0.05C, stopping charging, standing for 5min, discharging at constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Comparative example one:
step 1: and (3) self-assembling silicon dioxide with the same particle size to prepare a silica opal template, injecting a solution of the MOF-5 material into the gap of the silica opal template with the particle size of 200nm, carbonizing at high temperature, and washing away the silicon dioxide by hydrofluoric acid to obtain the current collector without gradient porosity.
And 2, step: mixing and stirring the sodium nickel manganese oxide, the conductive agent and the binder with a solvent uniformly according to the proportion of 92.
And step 3: and (3) assembling the current collector prepared in the step (1) and the positive plate prepared in the step (2) into a battery, and injecting electrolyte to prepare the non-negative-electrode sodium ion battery.
And 4, step 4: after the battery assembled in the step 3 is subjected to chemical composition and partial capacity, constant-current charge and discharge testing is carried out at 25 ℃, and the charge and discharge testing step comprises the following steps: charging with constant current of 1C multiplying power to 4V, charging with constant voltage of 4V to 0.05C, standing for 5min, discharging with constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 5: assembling the current collector (single surface) prepared in the step 1 and sodium metal to form a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises the following steps: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Comparative example two:
step 1: mixing and stirring the sodium nickel manganese oxide, the conductive agent and the binder with a second solvent uniformly according to a ratio of 92 to 3 to obtain slurry, coating the slurry on an aluminum foil, drying, and performing cold pressing to obtain the positive pole piece.
Step 2: and (3) assembling the Cu current collector and the positive plate prepared in the step (1) into a battery, and injecting electrolyte to prepare the non-negative-electrode sodium ion battery.
And step 3: after the battery assembled in the step 2 is subjected to chemical composition and partial capacity, constant-current charge and discharge tests are carried out at 25 ℃, and the charge and discharge tests comprise the following steps: charging with constant current of 1C multiplying power to 4V, charging with constant voltage of 4V to 0.05C, standing for 5min, discharging with constant current of 1C multiplying power to 2V, and standing for 5min; thus, the process is a cyclic process.
And 4, step 4: assembling a Cu current collector and sodium metal into a half cell, standing for 10 hours, and then carrying out charge and discharge test at normal temperature, wherein the charge and discharge test step comprises: depositing 2.0mAh/cm < 2 > at a current density of 1mA/cm < 2 >, standing for 10min, and then charging to 1.0V at a current density of 1mA/cm < 2 >, wherein the circulation process is adopted, and the coulomb efficiency and the polarization voltage of the sodium metal on different current collectors can be obtained.
Wherein, coulombic efficiency refers to the ratio of the discharge capacity of the battery to the charge capacity in the same circulation process. The polarization voltage is a direct current voltage applied between the diaphragm and the pole plate of the condenser microphone.
The cycle life results of the half cells obtained in step 5 of the first to fifth examples, the cycle life results of the half cell obtained in step 5 of the first comparative example, and the cycle life results of the half cell obtained in step 4 of the second comparative example were obtained by the above tests, and each cycle life result is shown in the following table one:
watch 1
|
Number of cycles
|
Polarization voltage
|
Coulombic efficiency
|
Example one
|
30
|
20.5mV
|
99.80%
|
Example two
|
30
|
18.0mV
|
99.90%
|
EXAMPLE III
|
30
|
14.3mV
|
99.95%
|
Example four
|
30
|
21.3mV
|
99.70%
|
EXAMPLE five
|
30
|
19.3mV
|
99.75%
|
Comparative example 1
|
30
|
38.0mV
|
99.50%
|
Comparative example No. two
|
30
|
50.0mV
|
80.20% |
Fig. 6 is a graph showing the capacity cycle retention rate and the number of cycles of the full cell obtained in step 4 in the first example, the capacity cycle retention rate and the number of cycles of the full cell obtained in step 4 in the first comparative example, and the capacity cycle retention rate and the number of cycles of the full cell obtained in step 3 in the second comparative example. As can be seen from fig. 6, the cycle count of the full cell obtained in step 4 of example one and the cycle count of the full cell obtained in step 4 of comparative example one both reached 100, whereas the cycle count of the full cell obtained in step 3 of comparative example only reached about 30. The value range of the capacity retention rate of the full cell obtained in the step 4 in the first embodiment is [80%,100% ], the value range of the capacity retention rate of the full cell obtained in the step 4 in the first embodiment is [70%,100% ], when the number of cycles of the full cell obtained in the step 4 in the first embodiment and the number of cycles of the full cell obtained in the first embodiment are both 100, the capacity retention rate of the full cell obtained in the step 4 in the first embodiment is about 86%, and the capacity retention rate of the full cell obtained in the step 4 in the first embodiment is about 74%.
In conclusion, the current collector 100 constructed by the present application has the advantages of high conductivity, huge reaction interface, unique gradient porosity distribution, nucleophilic nucleation sites, etc. The structure order can meet the requirement of electrochemical reaction uniformity; the high conductivity can provide a told electronic transmission path, reduce the impedance of the battery and improve the rate capability and the safety performance; the huge reaction interface can reduce the local current density, guide lithium/sodium ions to be uniformly deposited, prevent local overheating and improve the safety of the battery; the introduction of gradient porosity reduces the lithium/sodium ion concentration gradient in the electrolyte in the region near the separator, slowing the process of lithium/sodium precipitation. In the charging process, active metal ions are deposited from the pores with large pore diameters to the pores with small pore diameters, so that the formation of metal dendrites is effectively inhibited, and the safety performance, the rate capability and the cycle performance of the battery are improved.
The foregoing is a partial description of the present application, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations are also regarded as the protection scope of the present application.