CN114792793A - A sodium-ion battery additive and high-power sodium-ion battery - Google Patents

Abstract

The present invention relates to a sodium-ion battery additive and a high-power sodium-ion battery. The additive is β-alumina, and the chemical formula of the β-alumina is M ₂ O xAl ₂ O ₃ , wherein _M is one or more of the elements of group IA or group _IB in the periodic table of elements , x=5-11; the additive is used as an additive for the positive electrode material of sodium ion battery and/or the negative electrode material of sodium ion battery.

Description

A sodium-ion battery additive and high-power sodium-ion battery

technical field

The invention relates to the technical field of materials, in particular to a sodium-ion battery additive and a high-power sodium-ion battery.

Background technique

Under high-power application conditions (10C, minute-level response time), the cycle life of a single lithium-ion battery system under actual conditions will be greatly reduced. Usually, the combination of power type and energy type cells is used to improve Service life, high application cost.

At present, most of the high-power application conditions still use lead-acid batteries, but the service life of lead-acid batteries is only 2-3 years, and the industry still lacks effective methods in the recycling and treatment of lead-acid batteries to eliminate environmental pollution.

Sodium-ion batteries have many unique advantages, such as abundant raw material resources, low cost, environmental friendliness, high energy conversion efficiency, long cycle life, strong power characteristics and good safety, and can be widely used in various types of energy storage, including 5G communication base stations, Data center, emergency backup power supply, home energy storage and grid energy storage, etc. However, the current existing sodium-ion batteries cannot meet the requirements of high-rate charge-discharge performance, especially the application of high-power application conditions not lower than 10C.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide a sodium-ion battery additive and a high-power sodium-ion battery, which have high power, high safety and reliable performance, in view of the problems of short service life and great safety hazard of the battery under the existing high-power working condition.

In a first aspect, an embodiment of the present invention provides a sodium-ion battery additive, the additive is β-alumina, and the chemical formula of the β-alumina is M ₂ O·xAl ₂ O ₃ , where M is the periodic table of elements One or more of _IA group elements or _IB group elements, x=5-11;

The additive is used as an additive for the positive electrode material of sodium ion battery and/or the negative electrode material of sodium ion battery.

Preferably, the _IA group elements include: any one of Li, Na, K, and Rb; the _IB group includes Ag.

Preferably, the mass ratio of the additive in the positive electrode material of the sodium ion battery is 0.1%-30%; the mass ratio of the additive in the negative electrode material of the sodium ion battery is 1%-30%.

Preferably, the sodium ions in the sodium-ion battery migrate in the M-O plane of β-alumina.

In a second aspect, an embodiment of the present invention provides a high-power sodium-ion battery, including: a positive electrode, a negative electrode, a diaphragm, and an electrolyte;

The positive electrode comprises: positive electrode material, positive electrode binder, positive electrode conductive agent, positive electrode additive and positive electrode current collector; the negative electrode comprises: negative electrode material, negative electrode binder, negative electrode conductive agent, negative electrode additive and negative electrode current collector;

The positive electrode additive and/or the negative electrode additive includes the sodium ion battery additive described in the first aspect above.

In the positive electrode, the mass ratio of the positive electrode material is 60%-99%, the mass ratio of the positive electrode binder is 0.1%-20%, the mass ratio of the positive electrode conductive agent is 0.1%-20%, and the total mass ratio of the positive electrode additive is 0.1%-20%. The mass ratio is 0.1%-30%; the single-sided density of the positive electrode is 5.0-30.0 mg/cm ² ; the positive electrode current collector is an aluminum foil with a thickness of 4-30 μm;

The positive electrode material includes: any one of oxide positive electrode material, polyanion positive electrode material, Prussian blue positive electrode material, organic material and conversion positive electrode material;

Wherein, the general structural formula of the oxide cathode material is Na _x M1O ₂ , and M1 is one or more transition metal elements;

The general structural formula of the polyanion cathode material is Na _x M2 _y (X _a O _b ) _z Z _w , wherein M2 is Ti, V, Cr, Mn, Fe, Co, Ni, Ca, Mg, Al, One or more of Nb, etc.; X is one or more of Si, S, P, As, B, Mo, W, Ge; Z is F or OH;

The general structural formula of the Prussian blue cathode material is A _x M _a [M _b (CN) ₆ ] _(1-y)·y ·nH ₂ O, wherein 0≤x≤2, 0<y<1, A is an alkali metal ion, and _Ma and _Mb are one of Mn and Fe, respectively.

Preferably, in the negative electrode, the negative electrode material accounts for 60%-99% by mass, the negative electrode binder accounts for 0.1%-20% by mass, and the negative electrode conductive agent accounts for 0.1%-20% by mass, The mass ratio of the negative electrode additive is 1%-30%; the single-sided density of the negative electrode is 3.0-20.0 mg/cm ² ; the negative electrode current collector is aluminum foil or copper foil with a thickness of 4-30 μm;

The negative electrode material includes any one of soft carbon, hard carbon, composite amorphous carbon material or lithium titanate.

Preferably, the diaphragm includes: polypropylene, polyethylene, aramid, polyimide or non-woven diaphragm, or a ceramic-coated diaphragm based on the above materials, or a glue-coated diaphragm; Thickness is 5-50μm.

Preferably, the electrolyte is a mixed solution of electrolyte sodium salt and non-aqueous solvent;

The electrolyte sodium salt includes one or more of sodium hexafluorophosphate (NaPF ₆ ), sodium perchlorate, sodium tetrafluoroborate, sodium hexafluoroarsenate, and sodium chloroaluminate;

The non-aqueous solvent is a mixed solution of a chain ester and a cyclic ester, wherein the chain ester specifically includes dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), At least one of methyl propyl carbonate (MPC), dipropyl carbonate (DPC) and other fluorine-containing, sulfur-containing or unsaturated bond-containing chain organic esters; cyclic esters specifically include: ethylene carbonate ( At least one of EC), propylene carbonate (PC), vinylene carbonate (VC), sultone and other fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic esters;

The sodium salt concentration of the electrolyte is 0.2-2.0 mol/L.

Preferably, the high-power sodium ion battery is a cylindrical sodium ion battery, a square sodium ion battery or a soft pack battery.

The sodium ion battery additive provided by the invention is used as the positive electrode additive and/or negative electrode additive of the sodium ion battery, effectively reduces the internal resistance, improves the sodium ion migration performance, and can satisfy the charge and discharge rate of 5C-10C. , discharge time > 3min; charge-discharge cycle life > 1000 cycles at 1C/5C, capacity retention > 80%; the invention realizes the high-rate charge-discharge performance of cylindrical sodium-ion batteries for the first time, especially the high-rate charge performance, which can meet the Not less than 10C charging.

Description of drawings

The technical solutions of the embodiments of the present invention will be described in further detail below through the accompanying drawings and embodiments.

Fig. 1 is the rate performance test curve of the sodium ion battery provided in the embodiment of the present invention 2 at 0.2C-10C;

Fig. 2 is the rate performance test curve of the sodium ion battery provided by comparative example 1 of the present invention at 0.2C-10C;

Fig. 3 is the fast charge-discharge rate performance test curve of the sodium-ion battery provided by the embodiment of the present invention 2 under different charge-discharge conditions;

FIG. 4 is a test curve of the fast charge-discharge rate performance of the sodium-ion battery provided in Comparative Example 1 of the present invention under different charge-discharge conditions.

Detailed ways

The present invention will be further described below through the accompanying drawings and specific embodiments, but it should be understood that these embodiments are only used for more detailed description, and should not be construed as limiting the present invention in any form, that is, it is not intended to to limit the protection scope of the present invention.

The present invention provides a sodium ion battery additive, which is used as an additive for the positive electrode material of the sodium ion battery and/or the negative electrode material of the sodium ion battery. The additive is β-alumina, and the chemical formula of β-alumina is M ₂ O·xAl ₂ O ₃ , wherein _M is one or more of the elements of group IA or group _IB in the periodic table, and x is Positive integer; _IA group elements include: one or more of Li, Na, K or Rb, etc.; _IB group includes Ag and the like.

Taking Na-β-alumina as an example, the chemical formula is Na ₂ O·Al ₂ O ₃ , and its crystal structure is characterized by the fact that sodium ions are only in the loose plane (Na-O layer) containing equal amounts of sodium ions and oxygen ions, The two Na-O planes are 11.23 Angstroms apart, and four layers of oxygen atoms are sandwiched between the Na-O planes; according to the cubic closest packing arrangement, an appropriate amount of aluminum ions occupy the octahedral and tetrahedral positions. The close-packed base block composed of four close-packed oxygen layers and aluminum ions, the base blocks mirror each other on the top and bottom of the Na-O layer.

Due to the above-mentioned structural characteristics of Na-β-alumina, the Na-O layer is a loose structure of oxygen ions and sodium ions, and the distance between Na-O is 2.87 angstroms, while the Na-O in normal Na ₂ O The distance is 2.4 Angstroms, so Na ions can diffuse in two-dimensional space within the plane of the Na-O layer.

The diffusion mechanism of sodium ions on the Na-O surface can be considered that sodium ions occupy the interstitial positions between ions, and the diffusion effect is played by the ion transition between the interstitial positions and the normal positions. Therefore, by effectively enhancing the migration of sodium ions in the M-O plane of β-alumina, the internal resistance is reduced and the sodium ion migration performance is improved.

The additive was applied in high-power sodium-ion batteries. High-power sodium-ion batteries include: positive electrode, negative electrode, separator, and electrolyte.

The positive electrode comprises: positive electrode material, positive electrode binder, positive electrode conductive agent, positive electrode additive and positive electrode current collector; negative electrode comprises: negative electrode material, negative electrode binder, negative electrode conductive agent, negative electrode additive and negative electrode current collector; positive electrode additive and/or The negative electrode additive includes the above-mentioned sodium ion battery additive.

In the positive electrode, the mass ratio of the positive electrode material is 60%-99%, the mass ratio of the positive electrode binder is 0.1%-20%, the mass ratio of the positive electrode conductive agent is 0.1%-20%, and the mass ratio of the positive electrode additive is 0.1%-20%. The ratio is 0.1%-30%; the single-sided density of the positive electrode is 5.0-30.0 mg/cm ² ; the positive electrode current collector is an aluminum foil with a thickness of 4-30 μm;

The positive electrode material includes: any one of oxide positive electrode material, polyanion positive electrode material, Prussian blue positive electrode material, organic material and conversion positive electrode material;

Wherein, the general structural formula of the oxide cathode material is Na _x M1O ₂ , and M1 is one or more transition metal elements, such as iron-manganese-copper-based cathode materials or nickel-iron-manganese-based cathode materials; polyanion cathode materials The general structural formula is Na _x M2 _y (X _a O _b ) _z Z _w , wherein M2 is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Ca, Mg, Al, Nb, etc. X is one or more of Si, S, P, As, B, Mo, W, Ge; Z is F or OH; the general structural formula of Prussian blue cathode material is A _x M _a [M _b (CN) ₆ ] _(1-y)·y ·nH ₂ O, wherein 0≤x≤2, 0<y<1, A is an alkali metal ion, M _a and M _b are one of Mn and Fe, respectively .

In the negative electrode, the mass ratio of the negative electrode material is 60%-99%, the mass ratio of the negative electrode binder is 0.1%-20%, the mass ratio of the negative electrode conductive agent is 0.1%-20%, and the mass ratio of the negative electrode additive is 0.1%-20%. The ratio is 1%-30%; the single-sided density of the negative electrode is 3.0-20.0 mg/cm ² ; the negative electrode current collector is aluminum foil or copper foil with a thickness of 4-30 μm; the negative electrode material includes: soft carbon, hard carbon, composite amorphous Either carbon material or lithium titanate.

The separator includes: polypropylene, polyethylene, aramid, polyimide or non-woven separator, or a ceramic-coated separator based on the above materials, or a rubber-coated separator; the thickness of the separator is 5-50 μm.

The electrolyte is a mixed solution of an electrolyte sodium salt and a non-aqueous solvent; the electrolyte sodium salt includes one of sodium hexafluorophosphate (NaPF ₆ ), sodium perchlorate, sodium tetrafluoroborate, sodium hexafluoroarsenate, and sodium chloroaluminate. One or more; the non-aqueous solvent is a mixed solution of a chain ester and a cyclic ester, wherein the chain ester specifically includes dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate ( EMC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC) and at least one of other fluorine-containing, sulfur-containing or unsaturated bond-containing chain organic esters; cyclic esters specifically include: carbonic acid At least one of vinyl ester (EC), propylene carbonate (PC), vinylene carbonate (VC), sultone and other fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic esters; electrolyte The concentration of sodium salt is 0.2-2.0mol/L.

The high-power sodium ion battery of the present invention can be a cylindrical sodium ion battery, a square sodium ion battery or a soft pack battery.

In order to better understand the technical solutions provided by the present invention, several specific examples are used for further description below.

Example 1

Preparation of positive pole piece: add 100wt% solvent N-methylpyrrolidone (NMP) and 5wt% binder polyvinylidene fluoride (PVDF) powder into the planetary stirring cylinder, rotate at a speed of 30r/min and disperse at a speed of 3000r/min Stir for 2 hours, then add 5wt% of conductive agent carbon black (SP), stir for 1 hour at the speed of revolution 30r/min, dispersion 3000r/min, then add 5wt% Na-β-alumina, press revolution 30r/min , stirring at a speed of 3000r/min for 1 hour of dispersion, then adding 85wt% of the positive active material O3-Na[Cu _0.22 Fe _0.3 Mn _0.48 ]O ₂ , stirring for 3 hours at 30 r/min revolution and 3000 r/min dispersion, and then removing Bubble and pass through a 200-mesh sieve to complete the preparation of the positive electrode slurry for sodium-ion batteries;

The positive electrode slurry prepared above was evenly coated on an aluminum foil with a thickness of 15 μm by means of extrusion, and was dried, rolled and cut to prepare a positive electrode pole piece.

Preparation of negative pole piece: add 100wt% deionized water and 5wt% binder polyvinylidene fluoride (PVDF) powder into the planetary stirring cylinder, stir for 2 hours at the speed of revolution 30r/min and disperse 3000r/min, and then add 5wt% SP, stir for 1 hour at the speed of revolution 30r/min, disperse 3000r/min, then add 5wt% Na-β-alumina, stir for 1 hour at the speed of revolution 30r/min, disperse 3000r/min, and then Add 85wt% negative electrode active material anthracite hard carbon material, stir for 3 hours at 30 r/min revolution and 3000 r/min dispersion, then defoaming and sieving through 200 mesh sieve to complete the preparation of sodium ion battery negative electrode slurry;

The negative electrode slurry prepared above was evenly coated on an aluminum foil with a thickness of 15 μm by means of extrusion, and was dried, rolled and cut to prepare a positive electrode pole piece.

The obtained positive and negative electrode sheets are filmed, wound with a PE diaphragm coated with 12um+4um alumina ceramics, assembled and baked, and the liquid injection is 12g/piece, the concentration of sodium hexafluorophosphate is 1mol/L, and the solvent is carbonic acid. Ethylene ester (EC): diethyl carbonate (DEC): propylene carbonate (PC) = 1:1:1 electrolyte, after injection, the 26650 cells are prepared through the processes of chemical formation, aging, and volume separation. Number A1.

Example 2

The 26650 cell was prepared by the same method as in Example 1. The difference from Example 1 is that in the positive and negative electrode materials, the proportion of Na-β-alumina is 10wt%, and the proportion of positive and negative active materials is both 80wt% %, number A2.

Example 3

The 26650 cell was prepared by the same method as in Example 1. The difference from Example 1 is that in the positive and negative electrode materials, the proportion of Na-β-alumina is 15wt%, and the proportion of positive and negative electrode active materials is both 75wt% %, number A3.

Example 4

The 26650 cell was prepared by the same method as in Example 1. The difference from Example 1 is that in the positive and negative electrode materials, the proportion of Na-β-alumina is 20wt%, and the proportion of the positive and negative active materials is both 70wt% %, number A4.

Example 5

The 26650 cell was prepared by the same method as in Example 1. The difference from Example 1 is that in the positive and negative electrode materials, the proportion of Na-β-alumina is 25wt%, and the proportion of the positive and negative active materials is both 65wt% %, number A5.

Example 6

The 26650 cell was prepared by the same method as in Example 1. The difference from Example 1 is that in the positive and negative electrode materials, the proportion of Na-β-alumina is 30wt%, and the proportion of positive and negative active materials is both 60wt% %, number A6.

Comparative Example 1

26650 cells were prepared by the same method as in Example 1. The difference from Example 1 was that Na-β-alumina was not added to the positive and negative electrode slurry, and the ratio of positive and negative electrode active materials was 90%, number B1.

The assembled battery was tested for electrochemical performance using constant current-constant voltage charging mode and constant current discharging mode, and the cut-off voltage range of charge and discharge was 1.5-4V. The temperature is room temperature 25°C, and the test charge and discharge currents are 0.2C, 1C, 3C, 5C, 8C, and 10C. The test results are shown in Table 1.

Table 1

It can be seen from the data in Table 1 that the discharge capacity retention rates of A1-A6 and 0.2C/10C obtained in the examples are all greater than those of B1 obtained in the comparative example, indicating that the present invention has an obvious effect of improving the rate performance of the cells.

It can be seen from Example 2 and Comparative Example 1 in the data in Table 1 that the weight ratio of Na-β-alumina is 10%, and the rate performance is significantly improved

Fig. 1 is the rate performance test curve of the sodium ion battery provided by Example 2 of the present invention at 0.2C-10C; Fig. 2 is the rate performance test curve of the sodium ion battery provided by Comparative Example 1 at 0.2C-10C; It can be seen that the 10C discharge capacity in Example 2 is significantly larger than that in Comparative Example 1, and the improvement ratio is 5.1%.

Fig. 3 is the fast charge-discharge rate performance test curve of the sodium-ion battery provided by Example 2 of the present invention under different charge-discharge conditions; Fig. 4 is the fast-charge-discharge rate performance of the sodium-ion battery provided by Comparative Example 1 under different charge-discharge conditions From the comparison of the performance test curve, it can be seen that when charging and discharging at a high rate, the tests of Example 2 are ahead of those of Comparative Example 1. The greater the rate, the more obvious the gap is. Compared with the comparative example 1, the discharge retention rate is increased from 12.5% to 50%; the high-current charging capability is obviously improved.

The sodium ion battery additive provided by the invention is used as the positive electrode additive and/or negative electrode additive of the sodium ion battery, effectively reduces the internal resistance, improves the sodium ion migration performance, and can satisfy the charge and discharge rate of 5C-10C. , discharge time > 3min; charge-discharge cycle life > 1000 cycles at 1C/5C, capacity retention > 80%; the invention realizes the high-rate charge-discharge performance of cylindrical sodium-ion batteries for the first time, especially the high-rate charge performance, which can meet the Not less than 10C charging.

The specific embodiments described above further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. The sodium-ion battery additive is characterized in that the additive is beta-alumina, and the chemical formula of the beta-alumina is M ₂ O·xAl ₂ O ₃ Wherein M is I in the periodic table _A Group elements or I _B One or more of group elements, wherein x is 5-11;

the additive is used as an additive of a positive electrode material and/or a negative electrode material of a sodium-ion battery.

2. The sodium ion battery additive of claim 1, wherein I is _A The group elements include: any one of Li, Na, K and Rb; i is _B The group includes Ag.

3. The sodium-ion battery additive according to claim 1, wherein the mass ratio of the additive in the positive electrode material of the sodium-ion battery is 0.1-30%; the mass ratio of the additive in the negative electrode material of the sodium-ion battery is 1-30%.

4. The sodium ion battery additive according to claim 1, wherein sodium ions in the sodium ion battery migrate within the M-O plane of the beta alumina.

5. A high power sodium ion battery, comprising: a positive electrode, a negative electrode, a separator and an electrolyte;

wherein the positive electrode includes: the cathode comprises a cathode material, a cathode binder, a cathode conductive agent, a cathode additive and a cathode current collector; the negative electrode includes: the cathode comprises a cathode material, a cathode binder, a cathode conductive agent, a cathode additive and a cathode current collector;

the positive electrode additive and/or negative electrode additive comprises the sodium ion battery additive of claim 1.

6. The high-power sodium-ion battery according to claim 5, wherein in the positive electrode, the positive electrode material accounts for 60-99% by mass, the positive electrode binder accounts for 0.1-20% by mass, the positive electrode conductive agent accounts for 0.1-20% by mass, and the positive electrode additive accounts for 0.1-30% by mass; the single-sided surface density of the positive electrode is 5.0-30.0mg/cm ² (ii) a The positive current collector is an aluminum foil with the thickness of 4-30 mu m;

the positive electrode material includes: any one of an oxide positive electrode material, a polyanion positive electrode material, a prussian blue positive electrode material, an organic material and a conversion positive electrode material;

wherein the structural general formula of the oxide cathode material is Na _x M1O ₂ M1 is one or more of transition metal elements;

the structural general formula of the polyanion cathode material is Na _x M2 _y (X _a O _b ) _z Z _w Wherein M2 is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Ca, Mg, Al, Nb, etc.; x is one or more of Si, S, P, As, B, Mo, W and Ge; z is F or OH;

the structural general formula of the Prussian blue type anode material is A _x M _a [M _b (CN) ₆ ] _(1-y)·y ·nH ₂ O, wherein x is more than or equal to 0 and less than or equal to 2 and 0<y<1, A is an alkali metal ion, M _a 、M _b Respectively one of Mn and Fe.

7. The high-power sodium-ion battery according to claim 5, wherein in the negative electrode, the negative electrode material accounts for 60-99% by mass, the negative electrode binder accounts for 0.1-20% by mass, the negative electrode conductive agent accounts for 0.1-20% by mass, and the negative electrode additive accounts for 1-30% by mass; the single-sided density of the negative electrode is 3.0-20.0mg/cm ² (ii) a The negative current collector is an aluminum foil or a copper foil with the thickness of 4-30 mu m;

the anode material includes: any one of soft carbon, hard carbon, a composite amorphous carbon material, or lithium titanate.

8. The high power sodium ion battery of claim 5, wherein the separator comprises: polypropylene, polyethylene, aramid fiber, polyimide or non-woven fabric diaphragm, or ceramic coating diaphragm using the above materials as base materials, or gluing diaphragm; the thickness of the diaphragm is 5-50 μm.

9. The high power sodium ion battery of claim 5, wherein the electrolyte is a mixed solution of electrolyte sodium salt and non-aqueous solvent;

the sodium salt of the electrolyte comprises sodium hexafluorophosphate (NaPF) ₆ ) One or more of sodium perchlorate, sodium tetrafluoroborate, sodium hexafluoroarsenate and sodium chloroaluminate;

the non-aqueous solvent is a mixed solution of chain ester and cyclic ester, wherein the chain ester specifically comprises at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), Methyl Propyl Carbonate (MPC), dipropyl carbonate (DPC) and other chain organic esters containing fluorine, sulfur or unsaturated bonds; the cyclic acid ester specifically includes: at least one of Ethylene Carbonate (EC), Propylene Carbonate (PC), Vinylene Carbonate (VC), sultone and other cyclic organic esters containing fluorine, sulfur or unsaturated bonds;

the sodium salt concentration of the electrolyte is 0.2-2.0 mol/L.

10. The high power sodium ion battery of claim 5, wherein the high power sodium ion battery is a cylindrical sodium ion battery, a prismatic sodium ion battery, or a pouch battery.

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