CN116014225A - Sodium ion battery - Google Patents
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- CN116014225A CN116014225A CN202211737188.9A CN202211737188A CN116014225A CN 116014225 A CN116014225 A CN 116014225A CN 202211737188 A CN202211737188 A CN 202211737188A CN 116014225 A CN116014225 A CN 116014225A
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- 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 provides a sodium ion battery, which comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is positioned between the positive plate and the negative plate, the diaphragm comprises a base film and a ceramic coating arranged on one side of the base film facing the positive plate, the ceramic coating comprises a ceramic material, the surface of the ceramic material is provided with a metal-hydroxyl group, and the electrolyte comprises an ether solvent. Therefore, the ether solvent in the electrolyte can be adsorbed through the diaphragm, the oxidation resistance stability of the ether solvent is improved while the good reduction resistance stability of the ether solvent is maintained, and the ether solvent is prevented from being oxidized and decomposed, so that the energy efficiency and the quick charge performance of the sodium ion battery are improved.
Description
Technical Field
The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a sodium ion battery.
Background
The energy storage technology is a key for realizing sustainable use of intermittent clean energy, and compared with a lithium ion battery with continuously rising raw material prices and continuously generating safety problems, the sodium ion battery is gradually and widely focused as energy storage electrochemical electricity. However, the current sodium ion battery generally has the problem of poor performance such as circulation and quick charge, and the like, and needs to be solved.
Disclosure of Invention
The invention provides a sodium ion battery, which can improve the performances of quick charge, circulation and the like of the sodium ion battery and effectively overcome the defects existing in the prior art.
The invention provides a sodium ion battery, which comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is positioned between the positive plate and the negative plate, the diaphragm comprises a base film and a ceramic coating arranged on one side of the base film facing the positive plate, the ceramic coating comprises a ceramic material, the surface of the ceramic material is provided with a metal-hydroxyl group, and the electrolyte comprises an ether solvent.
According to an embodiment of the present invention, the metal-hydroxyl groups on the surface of the ceramic material include one or more of aluminum-hydroxyl groups, magnesium-hydroxyl groups, iron-hydroxyl groups, and silicon-hydroxyl groups.
According to one embodiment of the invention, the ceramic material comprises one or more of boehmite, sepiolite, montmorillonite and attapulgite, wherein the attapulgite has a structural formula of M 5 Si 8 O 20 (OH) 2 (OH 2 ) 4 ·4H 2 O and M are one or more of Mg, al, fe, ti, ca, na, K.
According to an embodiment of the present invention, in the ceramic coating layer, the mass content of the ceramic material is 50 to 99%.
According to an embodiment of the invention, the ceramic coating has a thickness of 1 to 20 μm.
According to an embodiment of the present invention, the base film comprises one or more of polypropylene, polyethylene, polyimide, polyurethane, and polyethylene terephthalate.
According to an embodiment of the present invention, the ether solvent includes one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran.
According to an embodiment of the present invention, the electrolyte further includes a sodium salt including one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium borohydride, and sodium trifluoromethane sulfonate.
According to one embodiment of the invention, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a conductive agent and a binder, and the load capacity of the positive electrode active material satisfies: the surface of the positive electrode current collector is loaded with 1-30 mg of positive electrode active material per square centimeter on average; and/or the positive electrode active material comprises one or more of sodium vanadium phosphate, sodium vanadium fluorophosphate, layered metal oxide and Prussian blue analogues.
According to an embodiment of the present invention, the negative electrode sheet is a negative electrode current collector, or the negative electrode sheet includes a negative electrode current collector, and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder, the negative electrode active material includes one or more of tin, bismuth, antimony, and phosphorus, and the negative electrode current collector includes one or more of aluminum foil, copper foil, carbon-coated aluminum foil, carbon-coated copper foil, and carbon fiber cloth.
According to the invention, the electrolyte comprises the ether solvent, so that the circulation stability of the sodium ion battery can be improved, meanwhile, the ceramic material in the ceramic coating is provided with the metal-hydroxyl group, so that the diaphragm has an adsorption effect on the ether solvent in the electrolyte, the ether solvent is directionally adsorbed by the diaphragm, and the electric double layer structure of the interface of the electrolyte and the anode is changed, thereby reducing the oxidative decomposition of the ether solvent on the surface of the anode while maintaining the reduction resistance of the electrolyte containing the ether solvent, improving the circulation, multiplying power, coulombic efficiency, quick charge and other performances of the sodium ion battery, and improving the energy efficiency of the sodium ion battery. The sodium ion battery provided by the embodiment of the invention has the advantages of low cost, convenience in preparation and the like, and is beneficial to actual large-scale and industrialized production.
Drawings
FIG. 1 is an ATR-FTIR spectrum of example 1 after the separator is immersed in an electrolyte;
FIG. 2 is a graph of the cycling performance (A of FIG. 2) and the coulombic efficiency (B of FIG. 2) of the sodium ion battery of example 1 at a current density of 1C;
FIG. 3 is a charge-discharge plot of the sodium-ion battery of example 2 at a current density of 1C;
FIG. 4 is a charge-discharge plot of the sodium-ion cell of comparative example 1 at a current density of 1C;
FIG. 5 is a graph of coulombic efficiency of the sodium ion battery of example 3;
fig. 6 is a coulombic efficiency plot of the sodium ion battery of comparative example 2.
Detailed Description
The present invention will be described in further detail below for the purpose of better understanding of the aspects of the present invention by those skilled in the art. The following detailed description is merely illustrative of the principles and features of the present invention, and examples are set forth for the purpose of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the examples of the invention without making any inventive effort, are intended to be within the scope of the invention.
The energy storage technology is a key for realizing sustainable use of intermittent clean energy, and compared with a lithium ion battery with continuously rising raw material prices and continuously generating safety problems, the sodium ion battery is gradually and widely focused as energy storage electrochemical electricity. However, the existing sodium ion battery generally has the problems of poor cycle performance and the like, and needs to be solved.
For example, according to the studies of the inventors, the replacement of a common hard carbon negative electrode with a sodium metal negative electrode or an alloyed negative electrode having a high theoretical capacity is expected to increase the energy density of a sodium ion battery to 200Wh kg -1 About, however, the large volume expansion of the alloyed negative electrode and the sodium metal negative electrode during charge and discharge causes the negative electrode-electrolyte interface to be difficult to stabilize, resulting in a rapid decay of the battery capacity. Stable circulation of the sodium metal negative electrode and the alloying negative electrode can be realized to a certain extent by adopting the ether electrolyte containing the ether solvent, and the realization of the function is derived from stronger reduction resistance of the ether electrolyte, however, the ether electrolyte generally has poorer oxidation resistance, and the unstable positive electrode-electrolyte interface (interface between the positive electrode and the electrolyte) limits the performances such as the cycle life, the quick charge performance and the like of the sodium ion battery based on the ether electrolyte, so how to keep the ether electrolyte resistant to furtherThe improvement of the oxidation resistance of the sodium ion battery is the key for improving the performances such as the circularity of the sodium ion battery.
In view of this, an embodiment of the present invention provides a sodium ion battery, including a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, the separator being located between the positive electrode sheet and the negative electrode sheet, the separator including a base film, and a ceramic coating layer disposed on a side of the base film facing the positive electrode sheet, the ceramic coating layer including a ceramic material, a metal-hydroxyl group being provided on a surface of the ceramic material, the electrolyte including an ether solvent.
In the embodiment of the invention, the electrolyte comprises the ether solvent, so that the circulation stability of the sodium ion battery can be improved, meanwhile, the ceramic material in the ceramic coating is provided with the metal-hydroxyl group, so that the diaphragm has an adsorption effect on the ether solvent in the electrolyte, the ether solvent is directionally adsorbed through the diaphragm, and the electric double layer structure of the interface between the electrolyte and the anode is changed, thereby reducing the oxidative decomposition of the ether solvent on the surface of the anode while maintaining the reduction resistance of the electrolyte containing the ether solvent, and improving the long-circulation and high-rate performance and other qualities of the sodium ion battery.
Specifically, the ether solvent carries an ether group, which can act with a metal-hydroxyl group in the ceramic coating, for example, the ether solvent and the metal-hydroxyl group are combined through the actions of hydrogen bond, covalent bond, coordination bond and the like, so that the ether solvent is adsorbed by the diaphragm, and further the oxidative decomposition of the ether solvent is avoided.
Specifically, the ceramic material contains a metal element and a substance having a hydroxyl group, and the metal-hydroxyl group is a group formed by bonding a metal element to a hydroxyl group.
Further research shows that the metal-hydroxyl groups on the surface of the ceramic material can comprise one or more of aluminum-hydroxyl groups, magnesium-hydroxyl groups, silicon-hydroxyl groups and iron-hydroxyl groups.
In some embodiments, the ceramic material may include one or more of boehmite, sepiolite, montmorillonite, and attapulgite having a formula M 5 Si 8 O 20 (OH) 2 (OH 2 ) 4 ·4H 2 O and M are one or more of Mg, al, fe, ti, ca, na, K.
The embodiment of the invention can realize that the surface of the ceramic material is provided with the metal-hydroxyl groups by a conventional method in the field, for example, the ceramic material is provided with the metal-hydroxyl groups, namely, the ceramic material is not subjected to any treatment and is provided with the metal-hydroxyl groups, namely, the embodiment of the invention can select the ceramic material (such as the attapulgite which is provided with the metal-hydroxyl groups); alternatively, the ceramic material may be subjected to hydroxylation treatment so as to have a hydroxyl group to form a metal-hydroxyl group with the metal element in the ceramic material, wherein the ceramic material may be subjected to hydroxylation treatment by a method conventional in the art, and this is not particularly limited.
In some embodiments, the ceramic coating may have a mass content of ceramic material (i.e., the ratio of the mass of ceramic material to the mass of ceramic coating) in the range of 50-98%, such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or any two of these.
In addition, the ceramic coating further includes a binder to improve adhesion between the ceramic materials and between the ceramic coating and the base film. The mass content of binder in the ceramic coating (i.e., the ratio of the mass of binder to the mass of the ceramic coating) may be in the range of 1-50%, such as 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any two of these.
According to the study of the inventor, if the ceramic coating is too thick, the energy density of the battery is affected to a certain extent, and sodium ion transmission is blocked, so that the thickness of the ceramic coating is generally controlled to be less than or equal to 20 mu m, and the influence on the energy density and the sodium ion transmission capability of the battery caused by the too thick ceramic coating can be avoided.
In some preferred embodiments, the ceramic coating may have a thickness in the range of 1 to 20 μm, for example 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm or any two thereof, such that adsorption of the ether solvent in the electrolyte by the separator through the ceramic coating may be enhanced, further weakening oxidative decomposition of the ether solvent, and simultaneously improving both the energy density and sodium ion transport capacity of the sodium ion battery.
Specifically, the base film has two opposite surfaces (i.e., opposite surfaces), one of which may be provided with a ceramic coating, and the other of which may be provided with no ceramic coating, or both of which may be provided with ceramic coatings.
The base film of the separator may be a polymer separator material conventional in the art, i.e., it may include a polymer. In some preferred embodiments, the base film comprises one or more of polypropylene, polyethylene, polyimide, polyurethane, and polyethylene terephthalate. In general, different polymer materials can enable the diaphragm to have different thermal stability mechanical properties, and when the diaphragm is implemented, a proper polymer can be selected as a base film of the diaphragm according to actual needs (such as a specific application scene of a sodium ion battery).
Specifically, the electrolyte comprises sodium salt and an organic solvent, and the organic solvent comprises the ether solvent. Wherein the concentration of the sodium salt can be 0.5 to 2mol L -1 For example 0.5mol L -1 、0.8mol L -1 、1mol L -1 、1.2mol L -1 、1.5mol L -1 、1.8mol L -1 、2mol L -1 Or a range of any two of these.
Specifically, the above-mentioned ether solvent may include an alcohol ether solvent and/or a furan-based solvent, wherein the alcohol ether solvent includes, for example, ethylene glycol dimethyl ether-based solvents such as one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and furan-based solvents such as tetrahydrofuran and/or 2-methyltetrahydrofuran, and the like.
In some preferred embodiments, the ether solvent comprises one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran and 2-methyltetrahydrofuran, so that the ether solvent can be better cooperated with the metal-hydroxyl groups in the ceramic coating, the ceramic coating can perform directional adsorption on the ether solvent, oxidative decomposition of the ether solvent at the positive electrode interface is weakened, and performances such as the battery circularity are improved.
In some embodiments, the sodium salt in the electrolyte may include one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium borohydride, sodium triflate.
Considering the viscosity, ionic conductivity, thermal stability and other factors of the electrolyte, preferably, sodium salt comprises sodium hexafluorophosphate, and the organic solvent in the electrolyte comprises diethylene glycol dimethyl ether.
In general, the separator has a porous structure, an electrolyte is immersed into pores of the separator, and an ether solvent in the electrolyte acts on metal-hydroxyl groups on the surface of the ceramic material, thereby being adsorbed. The ratio of the volume of the electrolyte to the surface area of the separator may be (2 to 20) μl:1cm 2 The surface area of the separator is the surface area of one side of the separator, specifically the surface area of the side of the separator facing the positive plate, that is, the surface area of the side of the separator facing the positive plate is S 1 The amount of electrolyte added (by volume) in the sodium ion battery is V, 2. Mu.L cm -2 ≤V/S 1 ≤20μL cm -2 ，V/S 1 For example 2. Mu.L cm -2 、5μLcm -2 、8μL cm -2 、10μL cm -2 、12μL cm -2 、15μL cm -2 、18μL cm -2 、20μL cm -2 Or a range of any two of these.
Specifically, the positive electrode sheet includes a positive electrode current collector, and a positive electrode active material layer provided on a surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material, a conductive agent, and a binder. The positive electrode active material layer may be present on one surface of the positive electrode current collector, or may be present on both opposite surfaces (i.e., both the front and back surfaces) of the positive electrode current collector.
In addition, the positive electrode active material is a sodium-containing active material such as one or more of vanadium sodium phosphate, vanadium sodium fluorophosphate, layered metal oxide, and prussian blue analog. Among them, the layered metal oxide may specifically include a ternary material containing sodium, which may be a conventional ternary material in the art as a sodium positive electrode material (i.e., positive electrode active material), for example, including a nickel-iron-manganese ternary material, etc., which is commercially available or self-made by a conventional method, without particular limitation.
By introducing the ceramic coating into the diaphragm, the ceramic coating comprises a ceramic material with metal-hydroxyl groups, and the ether solvent in the electrolyte is subjected to directional adsorption, so that the oxidation resistance stability of the ether solvent is improved, the sodium ion battery adopting the positive electrode active substances such as vanadium sodium phosphate, lamellar metal oxide and the like can maintain good performances such as circularity and circulation stability, and the sodium ion battery can maintain good performances such as circularity and circulation stability under high multiplying power.
In general, compared with the adoption of sodium vanadium phosphate as a positive electrode active material, the adoption of the layered metal oxide as the positive electrode active material is easier to cause the oxidative decomposition of an ether solvent in an electrolyte, and according to the research of the application, the adoption of the diaphragm, the ceramic material in the ceramic coating of which has metal-hydroxyl groups, can be well adapted to a sodium ion battery system adopting the layered metal oxide as the positive electrode material, keeps good reduction stability of the ether solvent, and improves the oxidation resistance of the ether solvent and weakens the oxidative decomposition of the ether solvent by adsorbing the ether solvent.
In addition, the load amount of the positive electrode active material may satisfy: the surface of the positive electrode current collector is loaded with 1-30 mg of positive electrode active material (namely, the characteristic loading capacity of the positive electrode active material is 1-30 mg cm) -2 ) That is, the surface (single-sided) area of the surface of the positive electrode current collector facing the positive electrode active material layer is S 2 The mass of the positive electrode active material in the positive electrode active material layer on one side (single side) of the positive electrode current collector is m, 1mg cm -2 ≤m/S 2 ≤30mg cm -2 。
The positive electrode sheet according to the embodiment of the present invention may be manufactured by a conventional method in the art, for example, a coating method, that is, a material such as a positive electrode active material, a conductive agent, a binder, etc. is placed in a solvent (such as N-methylpyrrolidone (NMP), etc.), and made into a slurry; and then coating the slurry on the surface of a positive electrode current collector, and drying, rolling and the like to obtain the positive electrode plate. The positive electrode current collector may be of a material conventional in the art, including, for example, aluminum foil and/or carbon-coated aluminum foil.
In addition, the negative electrode sheet comprises a negative electrode current collector, and the negative electrode current collector can comprise one or more of aluminum foil, copper foil, carbon-coated aluminum foil, carbon-coated copper foil and carbon fiber cloth.
The negative plate can be a negative current collector, namely, the negative current collector is directly used as the negative plate, and nano metal deposition stripping is carried out on the negative plate (negative current collector) in situ through positive electrode charge and discharge, which is equivalent to the formation of the negative-electrode-free sodium ion battery.
According to the research of the inventor, for a sodium ion battery directly adopting a negative electrode current collector, sodium ions are changed into sodium metal at a negative electrode, so that electrolyte which does not react with the sodium metal is needed, and an ether solvent does not react with the sodium metal, but is a good choice, but the ether solvent is easy to be subjected to oxidative decomposition, so that the battery performance is influenced.
Of course, the embodiment of the present invention is not limited to directly adopting the negative electrode current collector as the negative electrode sheet, and in other embodiments, the negative electrode sheet may further include a negative electrode active material layer disposed on the negative electrode current collector, where the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder, and the negative electrode active material includes one or more of tin, bismuth, antimony, and phosphorus.
Specifically, the anode active material may include a simple substance selected from one of tin, bismuth, antimony, and phosphorus, and may also include an alloy, for example, an alloy including at least two of tin, bismuth, antimony, and phosphorus, and the anode active material may specifically be in the micrometer scale.
According to the research of the invention, for the sodium ion battery adopting the negative electrode active material (simple substance, alloy and the like), the ceramic coating is introduced into the diaphragm, and the ceramic material in the ceramic coating is provided with the metal-hydroxyl group, so that the ether solvent in the electrolyte can be directionally adsorbed, the oxidation stability of the ether solvent can be improved while the good reduction stability of the ether solvent is maintained, the oxidative decomposition of the ether solvent is weakened, and the quality of the sodium ion battery such as the cycle stability, the service life and the like is improved.
In general, the specific capacity of the positive electrode sheet is in the range of 0.1 to 1.2 times, for example, 0.1 times, 0.3 times, 0.5 times, 0.8 times, 1 time, 1.2 times, or any two of these.
Specifically, the surface of the positive electrode sheet (the surface is perpendicular to the thickness direction of the positive electrode sheet) has an area S3 and a capacity A1, and the characteristic area specific capacity b1=a1/S3 of the positive electrode sheet; the surface of the negative electrode sheet (the surface is perpendicular to the thickness direction of the negative electrode sheet) has an area S4 and a capacity A2, and when the characteristic area specific capacity b2=a2/S4 of the negative electrode sheet, b2= (0.1 to 1.2) ×b1.
The characteristic area specific capacity of the positive plate is positively correlated with the loading capacity of the positive electrode active material in the positive plate, and the characteristic area specific capacity of the negative plate is positively correlated with the loading capacity of the negative electrode active material in the negative plate (when the negative plate does not have the negative electrode active material, the characteristic area specific capacity of the negative electrode does not need to be considered).
The anode sheet according to the embodiment of the invention can be prepared by a conventional method in the art, for example, a coating method, that is, materials such as an anode active material, a conductive agent, a binder and the like are placed in a solvent (such as water) to prepare a slurry; and then coating the slurry on the surface of a negative electrode current collector, and drying, rolling and the like to obtain the negative electrode plate.
In the embodiment of the present invention, the binder (such as a binder in a ceramic coating layer, a binder in a positive electrode active material layer, or a binder in a negative electrode active material layer) may be one or more of conventional binder materials in the art, such as polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyvinyl alcohol, sodium carboxymethyl cellulose, sodium alginate, and sodium polyacrylate.
In the embodiment of the present invention, the conductive agent (such as the conductive agent in the ceramic coating layer, the conductive agent in the positive electrode active material layer, or the conductive agent in the negative electrode active material layer) used may be a conventional conductive material in the art, including, for example, carbon black and the like.
The sodium ion battery in the embodiment of the invention can be a button battery, a cylindrical battery, a soft package battery and the like, and is not particularly limited.
The sodium ion battery of the embodiments of the present invention may be manufactured by a method conventional in the art, and illustratively, the manufacturing process thereof may include: the positive electrode, the diaphragm and the negative electrode are sequentially stacked (i.e. stacked), wherein one side of the diaphragm facing the positive electrode plate is provided with the ceramic coating, for example, when the diaphragm consists of a base film and the ceramic coating arranged on one surface of the base film, the ceramic coating of the diaphragm faces the positive electrode plate; then, the subsequent processes of electrolyte injection, packaging and the like are carried out to form the sodium ion battery.
For the purpose of promoting an understanding of the principles of the invention, reference will now be made in detail to specific examples, some but not all of which are illustrated in the accompanying drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the following examples and comparative examples, the layered metal oxide (positive electrode active material) used was a ternary nickel-iron-manganese material (i.e., ternary layered metal oxide based on nickel, iron, manganese) purchased from Shenzhen Kogyo Co., ltd, sodium vanadium phosphate was used from Shenzhen Kogyo Co., ltd, and attapulgite was used from microphone.
Example 1
Placing layered metal oxide, polyvinylidene fluoride and carbon black into a solvent according to the mass ratio of 8:1:1 to prepare slurry; coating the slurry on the front surface and the back surface of an aluminum foil, forming a positive electrode active material layer through drying and rolling, and then cutting into positive electrode plates with preset shapes;
tin (anode active material), sodium polyacrylate and carbon black are placed in a solvent according to the mass ratio of 8:1:1 to prepare slurry; coating the slurry on the front surface and the back surface of an aluminum foil, forming a negative electrode active material layer through drying and rolling, and then cutting into a negative electrode plate with a preset shape;
wherein, the characteristic area specific capacity of the negative plate is 0.4 times of the characteristic area specific capacity of the positive electrode, namely B2=0.4×B1.
Sequentially stacking the positive plate, the diaphragm and the negative plate, and preparing a sodium ion battery after the procedures of liquid injection (electrolyte injection), encapsulation and the like;
wherein, the addition amount of the electrolyte meets the following conditions: the ratio of the volume of the electrolyte to the surface area of the separator was 10. Mu.L cm -2 (i.e. V/S) 1 ＝10μL cm -2 ) The method comprises the steps of carrying out a first treatment on the surface of the The electrolyte consists of diethylene glycol dimethyl ether and sodium hexafluorophosphate, and the concentration of the sodium hexafluorophosphate in the electrolyte is 1mol L -1 ；
Wherein the diaphragm (marked as an attapulgite ceramic diaphragm) consists of a base film and a ceramic coating arranged on one surface of the base film, the base film is a polypropylene film, the ceramic coating comprises attapulgite containing magnesium and aluminum and polyvinylidene fluoride, the mass content of the attapulgite in the ceramic coating is about 85 percent, and the balance is a binder; the thickness of the ceramic coating was 20 μm.
Referring to the procedure of example 1, sodium ion batteries of example 2, example 3, comparative example 1, and comparative example 2 were produced, and the sodium ion batteries of examples 1 to 3, and comparative examples 1 to 2 were different in that the positive electrode active material, separator, or negative electrode sheet used was different, specifically, see table 1, except for the differences shown in table 1, and the other conditions were the same.
TABLE 1
The separator and sodium ion battery of each example and comparative example were tested as follows:
(1) ATR-FTIR analysis
(1-1) analytical procedure
Characterization of the membrane-modified ether electrolyte/electrode interface by attenuated total reflection Fourier transform infrared (ATR-FTIR) method comprises the steps of dripping 10 μl of electrolyte onto a ceramic membrane with a diameter of 16mm, and performing ATR-FTIR test on the ceramic surface of the membrane to obtain ATR-FTIR spectrum of the ceramic membrane impregnated with the electrolyte (such as the spectrum corresponding to "ceramic membrane+electrolyte" in FIG. 1);
in addition, ATR-FTIR analysis is carried out on the ceramic diaphragm (electrolyte is not added dropwise), and an ATR-FTIR spectrum of the ceramic diaphragm (such as a spectrum corresponding to a 'ceramic diaphragm' in FIG. 1) is obtained;
in addition, ATR-FTIR analysis was performed on the electrolyte to obtain an ATR-FTIR spectrum of the electrolyte (e.g., a spectrum corresponding to "electrolyte" in FIG. 1).
(1-2) analysis results
The analysis result of the analysis process shows that the solvent peak of ATR-FTIR of the diaphragm impregnated with the electrolyte is obviously deviated, the adsorption effect of the attapulgite ceramic diaphragm on the ether solvent in the electrolyte is shown, the ether electrolyte-anode interface is regulated and controlled through the adsorption effect, and the oxidative decomposition of the solvent is weakened.
Taking the test results of the attapulgite ceramic membrane of example 1 as an example (the test results of example 2 and example 3 are similar to those of example 1), fig. 1 specifically shows the corresponding ATR-FTIR spectra obtained by performing the above-described analysis procedure of (1-1) using the attapulgite ceramic membrane of example 1, that is, ATR-FTIR spectra of the ceramic membrane impregnated with the electrolyte (the spectrum corresponding to "ceramic membrane+electrolyte" in fig. 1), ATR-FTIR spectra of the ceramic membrane (the spectrum corresponding to "ceramic membrane" in fig. 1), ATR-FTIR spectra of the electrolyte (the spectrum corresponding to "electrolyte" in fig. 1). As can be seen from fig. 1, the solvent peak of ATR-FTIR measured with the attapulgite ceramic membrane is significantly shifted, which indicates that the adsorption of the ether solvent in the electrolyte by the attapulgite ceramic membrane, by which the ether electrolyte-positive electrode interface is regulated and controlled, the oxidative decomposition of the solvent is reduced.
(2) Constant current charge and discharge tests are carried out on the sodium ion battery at 25 ℃, and the charge specific capacity, the discharge specific capacity, the coulombic efficiency and the like of each cycle are recorded so as to test the rate capability and the cycle capability of the sodium ion battery. Fig. 2 is a cycle performance graph (a curve of specific capacity versus cycle number, see fig. 2 a) and a coulombic efficiency graph (a curve of coulombic efficiency versus cycle number, see fig. 2B) of the sodium-ion battery of example 1, fig. 3 is a charge-discharge graph of the sodium-ion battery of example 2 at a current density of 1C, fig. 4 is a charge-discharge graph of the sodium-ion battery of comparative example 1 at a current density of 1C, fig. 5 is a coulombic efficiency graph of the sodium-ion battery of example 3, and fig. 6 is a coulombic efficiency graph of the sodium-ion battery of comparative example 2.
According to the test results of example 1, as shown in fig. 2, the attapulgite ceramic separator can be well adapted to sodium-ion battery systems using layered metal oxide as a positive electrode material and micron-sized tin as a negative electrode active material, and its excellent performance is derived from factors such as good reduction resistance stability of ether solvents, and oxidation resistance stability of ether electrolytes in electrolyte solutions can be improved by ceramic coating of the attapulgite ceramic separator.
According to the test results of example 2 and comparative example 1, as shown in fig. 3 and 4, example 2 can significantly improve the coulombic efficiency of a non-negative electrode (directly using a carbon-coated aluminum foil as a negative electrode sheet) sodium battery based on layered metal oxide, inhibit the decomposition of the electrolyte, and thereby improve the energy efficiency of the sodium ion battery.
According to the test results of example 3 and comparative example 2, as shown in fig. 5 and 6, example 3 can significantly improve the cycle stability and coulombic efficiency of the negative electrode-free sodium battery based on the positive electrode of sodium vanadium phosphate at a large current (4C), thereby improving the energy efficiency of the battery.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. The sodium ion battery is characterized by comprising a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is positioned between the positive plate and the negative plate, the diaphragm comprises a base film and a ceramic coating arranged on one side of the base film facing the positive plate, the ceramic coating comprises a ceramic material, the surface of the ceramic material is provided with a metal-hydroxyl group, and the electrolyte comprises an ether solvent.
2. The sodium ion battery of claim 1, wherein the metal-hydroxyl groups of the ceramic material surface comprise one or more of aluminum-hydroxyl groups, magnesium-hydroxyl groups, iron-hydroxyl groups, and silicon-hydroxyl groups.
3. The sodium ion battery of claim 1 or 2, wherein the ceramic material comprises one or more of boehmite, sepiolite, montmorillonite and attapulgite, and the structural formula of the attapulgite is M 5 Si 8 O 20 (OH) 2 (OH 2 ) 4 ·4H 2 O and M are one or more of Mg, al, fe, ti, ca, na, K.
4. The sodium ion battery according to claim 1, wherein the ceramic material is contained in the ceramic coating in an amount of 50 to 99% by mass.
5. The sodium ion battery of claim 1, wherein the ceramic coating has a thickness of 1 to 20 μm.
6. The sodium ion battery of claim 1, wherein the base film comprises one or more of polypropylene, polyethylene, polyimide, polyurethane, polyethylene terephthalate.
7. The sodium ion battery of claim 1, wherein the ether solvent comprises one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran.
8. The sodium ion battery of claim 1 or 7, wherein the electrolyte further comprises a sodium salt comprising one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium borohydride, sodium triflate.
9. The sodium ion battery of claim 1, wherein the positive electrode sheet comprises a positive electrode current collector, and a positive electrode active material layer provided on a surface of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, a conductive agent, and a binder, wherein,
the positive electrode active material loading satisfies: the surface of the positive electrode current collector is loaded with 1-30 mg of positive electrode active material per square centimeter on average;
and/or the positive electrode active material comprises one or more of sodium vanadium phosphate, sodium vanadium fluorophosphate, layered metal oxide and Prussian blue analogues.
10. The sodium ion battery of claim 1, wherein the negative electrode sheet is a negative electrode current collector, or the negative electrode sheet comprises a negative electrode current collector, and a negative electrode active material layer arranged on the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, a conductive agent and a binder, the negative electrode active material comprises one or more of tin, bismuth, antimony and phosphorus, and the negative electrode current collector comprises one or more of aluminum foil, copper foil, carbon-coated aluminum foil, carbon-coated copper foil and carbon fiber cloth.
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| CN202211737188.9A CN116014225A (en) | 2022-12-30 | 2022-12-30 | Sodium ion battery |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117175016A (en) * | 2023-09-21 | 2023-12-05 | 北京希倍动力科技有限公司 | Negative-electrode-free sodium ion secondary battery, electrolyte and application thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117175016A (en) * | 2023-09-21 | 2023-12-05 | 北京希倍动力科技有限公司 | Negative-electrode-free sodium ion secondary battery, electrolyte and application thereof |
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