CN115954466B - Mixed active material and lithium-sodium mixed ion battery - Google Patents
Mixed active material and lithium-sodium mixed ion battery Download PDFInfo
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Abstract
The invention relates to the technical field of secondary batteries, in particular to a mixed active material and lithium sodium mixed ion battery, wherein the mixed active material is formed by mixing a high-nickel positive electrode material and a sodium iron sulfate positive electrode material; the lithium-sodium mixed ion battery comprises a positive pole piece, a negative pole piece, electrolyte and a diaphragm, wherein the positive pole piece comprises a positive current collector and a positive material; the positive electrode material comprises a mixed active material, a conductive agent and a binder; the energy density of the high-nickel positive electrode material is obviously superior to that of the sodium ferric sulfate positive electrode material, but the low temperature resistance, the high rate performance and the cycle stability performance of the lithium sodium mixed ion battery are poor.
Description
Technical Field
The invention relates to the technical field of secondary batteries, in particular to a mixed active material and lithium-sodium mixed ion battery.
Background
The lithium ion battery has the characteristics of high working voltage, high energy density, long service life, portability, recoverability, low carbon, environmental protection and the like, and becomes a main stream battery product required in the fields of consumer electronics, new energy automobiles, energy storage systems and the like. The lithium battery industry in China is greatly supported by national policies, and the industry chain is highly mature and continuously enters a high-speed development stage. The lithium battery using nickel cobalt lithium manganate oxide as the positive electrode material is commonly called a high-nickel ternary lithium battery, and compared with the ferric phosphate lithium battery, the high-nickel ternary lithium battery has higher working voltage and energy density, and has been widely applied to new energy passenger vehicles as a power battery. The working voltage platform is an important index of the energy density of the battery, determines the basic efficiency and cost of the battery, and the higher the working voltage platform is, the larger the specific energy is. Therefore, the battery with the same volume and weight and even the same ampere-hour condition has longer endurance time than the ternary material lithium battery with a higher working voltage platform. However, in a low-temperature environment, the capacity of the ternary lithium battery decays too fast, and the high rate and long cycle life in a normal-temperature working environment are not ideal, which restricts the practical application of the ternary lithium battery, and a technical scheme for solving the problems is needed.
The working principle of the sodium ion battery is similar to that of a lithium ion battery, and the sodium ion battery has obvious advantages in low-temperature performance, cycle safety, high-rate performance, large-scale production cost and the like, has energy density between the lithium ion battery and a lead-acid battery, and has market attention due to unique advantages under the background of limited lithium resources. The ferric sodium sulfate material has stable structure, small volume change of crystal structure and no phase change in the intercalation and deintercalation process of sodium ions, so that the long-term circulation stability is good, the safety is high, and the low-temperature and low-rate performance also has advantages. In addition, the wide working voltage (2.0-4.5V vs. Na+/Na) of the ferric sodium sulfate positive electrode material can completely cover the working voltage (2.7-4.3V vs. Li+/Li) of the high-nickel positive electrode material, and the two positive electrode materials have similar working voltage platforms, so that the mixed use of the ferric sodium sulfate material and the high-nickel material on the material level provides possibility, and the practical application problem of the high-nickel battery is hopefully solved, and the lithium-sodium mixed ion battery with high energy density and excellent cycle, multiplying power and low-temperature performance is obtained; therefore, the invention develops a mixed active material and lithium-sodium mixed ion battery to solve the problems in the prior art.
Disclosure of Invention
The invention aims at: the mixed active material and lithium-sodium mixed ion battery is provided to solve the problems that in the prior art, under a low-temperature environment, the capacity of a high-nickel lithium battery decays too fast, and the high multiplying power and the long cycle life under a normal-temperature working environment are not ideal, so that the practical application of the battery is restricted.
The technical scheme of the invention is as follows: a mixed active material comprises a high nickel positive electrode material and a sodium iron sulfate positive electrode material, and is formed by mixing.
Preferably, the molecular formula of the high nickel positive electrode material is LiNi 1-x TM x O 2 Wherein x is more than or equal to 0 and less than or equal to 0.5, and TM is one or a combination of more of Co, mn, al and Fe;
the molecular formula of the sodium iron sulfate positive electrode material is Na m Fe(SO 4 ) n Wherein n= (m+2)/2,1.0 is less than or equal to m and less than or equal to 3.0.
Preferably, the mass percentage of the ferric sodium sulfate positive electrode material to the mixed active material is Qwt%, Q and x are positively correlated, and Q epsilon [0.1, 99.9].
Based on a positive electrode material, the invention also develops a lithium-sodium mixed ion battery which comprises a positive electrode plate, a negative electrode plate, electrolyte and a diaphragm, and is characterized in that: the positive electrode plate comprises a positive electrode current collector and a positive electrode material formed on the positive electrode current collector; the positive electrode material comprises the mixed active material, a conductive agent and a binder;
the negative electrode plate adopts a lithium metal negative electrode or adopts a combination of a negative electrode current collector and a negative electrode material, wherein the negative electrode material is formed on the negative electrode current collector and comprises a negative electrode active material, a conductive agent and a binder;
the electrolyte comprises an organic solvent, inorganic salt and an additive;
the separator separates the positive pole piece from the negative pole piece.
Preferably, in the positive electrode material, the mixed active material has 80 to 99.8 parts by weight, the conductive agent has 0.1 to 10 parts by weight, and the binder has 0.1 to 10 parts by weight.
Preferably, the compaction density of the positive electrode plate is 1.5g/cm 3 ～3.5g/cm 3 The compacted density of the negative electrode plate is 0.5g/cm 3 ～1.5g/cm 3 。
Preferably, about the negative electrode sheet and the positive electrode sheet, 0.95.ltoreq.N W *N A *N g ）/（P W *P A *P g ) Less than or equal to 1.36, wherein:
N W 、P W the content of the negative electrode active material and the content of the mixed active material are respectively;
N A 、P A the coating surface density of the anode material and the coating surface density of the cathode material are respectively;
N g 、P g the negative electrode reversible gram capacity and the positive electrode reversible gram capacity are respectively.
Preferably, in the negative electrode material, 80-98 parts of the negative electrode active material, 1-10 parts of the conductive agent and 1-10 parts of the binder are calculated according to parts by weight.
Preferably, the conductive agent in the positive electrode material and the negative electrode material is any one or a combination of at least two of conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes or carbon nanofibers; and/or the number of the groups of groups,
the binder in the positive electrode material and the negative electrode material adopts any one or a combination of at least two of polyvinylidene fluoride, modified polyvinylidene fluoride, polyvinylidene chloride, modified polyvinylidene chloride, polyvinylidene fluoride copolymer, polyvinylidene chloride copolymer, polymethyl methacrylate or styrene butadiene rubber; and/or the number of the groups of groups,
the inorganic salt in the electrolyte adopts LiPF 6 、LiBF 4 、LiClO 4 、LiAsF 6 、LiN(CF 3 SO 2 ) 2 、LiC(CF 3 SO 2 ) 3 、LiB(C 2 O 4 ) 2 、LiBOB、NaClO 4 、NaPF 6 、Na[(FSO 2 ) 2 N]One or more of the following; the concentration of the inorganic salt is 0.5-2 mol/L; and/or the number of the groups of groups,
the positive current collector adopts any one of aluminum foil and carbon-coated aluminum foil, and porous aluminum foil; and/or the number of the groups of groups,
the negative current collector adopts copper foil; and/or the number of the groups of groups,
the diaphragm adopts polyethylene, polypropylene, polyethylene+polypropylene, polyethylene+Al 2 O 3 Coating, polypropylene+Al 2 O 3 Any one of the coatings.
Compared with the prior art, the invention has the advantages that:
(1) Based on the characteristics of the positive electrode material, the prepared lithium-sodium mixed ion battery has Na separated from sodium ferric sulfate components in the circulating process + Can partially enter Li layer with high nickel content to increase interlayer spacing and support in structure of high nickel material, and is favorable for Li + The subsequent reversible deintercalation of the high-nickel positive electrode material improves the lithium storage dynamics and the structural stability of the high-nickel positive electrode material, and shows better high-rate quick charge characteristics and long-cycle stability. At the same time due to Li + Radius (0.76 a) compared to Na + Radius (1.02A) is smaller, li + The method can be used for more conveniently and reversibly deintercalating in the crystal structure of the sodium iron sulfate, so that the diffusion capability of lithium ions in the crystal lattice of the sodium iron sulfate anode material is improved. Therefore, the lithium-sodium mixed ion battery can have both high energy density and excellent high-rate and long-cycle life characteristics.
(2) The high-nickel positive electrode material has energy density superior to that of the ferric sodium sulfate positive electrode material, but has poor low temperature resistance, and based on the fact that the ferric sodium sulfate positive electrode material and the high-nickel positive electrode material have a matched working voltage interval and a voltage platform, the ferric sodium sulfate positive electrode material and the high-nickel positive electrode material are mixed according to a certain mass ratio to obtain a mixed active material, so that the prepared lithium-sodium mixed ion battery not only ensures high working voltage and energy density, but also improves high-rate, long-cycle and low-temperature working performance of the lithium-sodium mixed ion battery.
Drawings
The invention is further described below with reference to the accompanying drawings and examples:
FIG. 1 is a graph showing the 25 ℃ rate discharge performance of a lithium-sodium ion battery according to the first comparative example 1 and example 2;
FIG. 2 is a graph showing the comparison of the 25 ℃ rate charge-discharge performance of a lithium-sodium ion battery according to the first group of comparison examples 1 and 2;
FIG. 3 is a graph showing the comparison of the retention rate of charge and discharge capacity at 25℃of a lithium-sodium ion battery according to the first group of comparison of the present invention, which is described in example 1 and example 2;
FIG. 4 is a graph showing the charge and discharge performance at-20deg.C of a lithium-sodium ion battery according to the first comparative example 1 and example 2;
FIG. 5 is a graph showing the charge-discharge curves of a lithium-sodium ion battery of-20deg.C according to the first comparative examples of the present invention;
FIG. 6 is a graph showing the charge and discharge curves of example 3 and example 4 in a second comparison of the present invention;
FIG. 7 is a graph showing the charge and discharge curves of example 5 and example 6 in a third comparative set of the present invention;
fig. 8 is a charge-discharge graph of example 7, example 8, example 9, example 10 in the fourth comparative group of the present invention.
Detailed Description
The following describes the present invention in further detail with reference to specific examples:
[ first group of comparisons ]
a. Example 1
A lithium-sodium mixed ion battery comprises a positive electrode plate, a negative electrode plate, electrolyte and a diaphragm; wherein:
(1) Regarding the positive electrode sheet, it includes a positive electrode current collector, and a positive electrode material formed on the positive electrode current collector; the positive electrode material comprises a mixed active material of a high-nickel positive electrode material and a sodium ferric sulfate positive electrode material, a conductive agent and a binder.
Preparation of positive electrode sheet:
96.5wt% of mixed active material, 1.7wt% of PVDF (polyvinylidene fluoride-binder), 0.7wt% of SP (conductive carbon black-conductive agent), 1.1wt% of MWCNT (carbon nano tube-conductive agent) and NMP (N-methylpyrrolidone) are adopted as solvents; wherein, the high nickel-based positive electrode material and the ferric sodium sulfate positive electrode material have a matched working voltage interval and voltage platform,by LiNi 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2; uniformly stirring the raw materials, coating the raw materials on the surface of a 13 mu m carbon-coated aluminum foil of a positive current collector, baking at 85 ℃, rolling, die cutting, and compacting to 2.4g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
(2) The negative electrode plate comprises a negative electrode current collector and a negative electrode material or a lithium metal negative electrode formed on the negative electrode current collector; the anode material includes an anode active material, a conductive agent, and a binder.
Preparation of a negative electrode sheet:
homogenizing 94wt% of anode active material hard carbon, 2wt% of SP (conductive agent), 2.8wt% of SBR (styrene butadiene rubber-binder) and 1.2wt% of CMC (binder) in the presence of deionized water as a solvent, coating the slurry on a 6 mu m copper foil, baking at 85 ℃, rolling, die-cutting and compacting to 0.92g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
When the negative electrode sheet and the positive electrode sheet are prepared, the content of the negative electrode active material is 1.08, namely the coating surface density is the reversible gram capacity of the negative electrode/(the content of the mixed active material is the reversible gram capacity of the positive electrode).
(3) Regarding the electrolyte, an organic solvent, an inorganic salt, and an additive are included; wherein the inorganic salt adopts 1mol/L LiPF 6 The molar ratio of the organic solvent, the inorganic salt and the additive is 4.5:4.5:1.
(4) Regarding the separator, polypropylene+Al is used for separating the positive electrode plate from the negative electrode plate 2 O 3 And (3) coating.
Preparation of lithium-sodium mixed ion battery:
and sequentially stacking the negative electrode plate, the diaphragm and the positive electrode plate by using a lamination machine to prepare a bare cell, wherein the diaphragm is positioned between the positive electrode plate and the negative electrode plate to play a role in isolation, the ceramic faces the negative electrode plate, and then the preparation of the lithium-sodium mixed ion battery is finished through the procedures of welding, top side sealing, liquid injection, formation, secondary sealing and capacity division, the production environment is required to be controlled in the lamination process, and the dew point requirement of a workshop is less than-45 ℃.
b. Example 2
Preparation of positive electrode sheet: 96.5wt% of high nickel positive electrode active material, 1.7wt% of PVDF, 0.7wt% of SP, 1.1wt% of MWCNT and NMP as a solvent are adopted; wherein, liNi is adopted 0.8 Co 0.1 Mn 0.1 O 2 As a high nickel positive electrode active material; uniformly stirring the raw materials, coating the raw materials on the surface of a 13 mu m carbon-coated aluminum foil of a positive current collector, baking at 85 ℃, rolling, die cutting, and compacting to 2.4g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
Preparation of a negative electrode sheet: homogenizing 94wt% of anode active material hard carbon, 2wt% of SP, 2.8wt% of SBR and 1.2wt% of CMC under the condition of taking deionized water as a solvent, coating the slurry on a 6 mu m copper foil, baking at 85 ℃, rolling, die-cutting and compacting to 0.92g/m 3 Baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing; wherein, the content of the negative electrode active material is 1.08, which is the coating surface density, the negative electrode reversible gram capacity/(the content of the mixed active material is the coating surface density, and the positive electrode reversible gram capacity).
Regarding the electrolyte, an organic solvent, an inorganic salt, and an additive are included; wherein the inorganic salt adopts 1mol/L LiPF 6 The molar ratio of the organic solvent, the inorganic salt and the additive is 4.5:4.5:1.
regarding the separator, polypropylene+Al is used for separating the positive electrode plate from the negative electrode plate 2 O 3 And (3) coating.
In a first set of comparisons, example 1 and example 2 are directed to the preparation of batteries, the relevant parameters are as follows:
| first group of | Mixed/high nickel positive electrode active material | Mass ratio | Negative electrode active material |
| Example 1 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Hard carbon |
| Example 2 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 （NCM811） | —— | Hard carbon |
The active material of example 1 was a combination of a high nickel positive electrode material and a sodium iron sulfate positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 +Na 1.5 Fe(SO 4 ) 1.75 ) In example 2, the active material was only a high nickel positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) The method comprises the steps of carrying out a first treatment on the surface of the Aiming at the lithium-sodium mixed ion battery prepared by two different anode materials, performance test is required to be carried out on the lithium-sodium mixed ion battery; as shown in fig. 1, at the time of 25 ℃ rate discharge test, 0.33C was charged to 4.3V, and 0.33C, 1C, 3C, 5C, 10, 15C was discharged to 2.75V, respectively, and discharge capacities were recorded; as shown in fig. 2, during the 25 ℃ rate charge-discharge test, the discharge capacity is recorded by circulating 3 circles under the voltage interval of 2.75-4.3V with currents of 0.33C, 1C, 5C, 10C and 15C respectively; as shown in figure 3, when the charge-discharge cycle test is carried out at 25 ℃, the battery cell is in a constant temperature box at 25 ℃ and the charge-discharge cycle is carried out by 3V-4.2V and 1C current; as shown in FIG. 4, in the-20deg.C rate charge-discharge test, 0.33C is charged to 4.3V, and 0.33C is dischargedCycling the voltage to 2.4V, and recording the discharge capacity for 5 times; 1C was charged to 4.3V, 1C was discharged to 2.4V, cycled 5 times, and the discharge capacity was recorded; as shown in FIG. 5, when the charge-discharge cycle test is carried out at-20 ℃, the charge-discharge cycle test is carried out by using 2.4V-4.3V and 0.33C current; as shown in fig. 1 to 5, it is known by comparison that the lithium-sodium mixed ion battery has more excellent long-cycle capacity retention rate and high-rate discharge capacity, and has lower capacity attenuation rate and more rate performance in a low-temperature environment. Therefore, the lithium-sodium mixed ion battery provided by the invention provides a feasible technical route for being used as a power battery in improving the endurance mileage of a new energy automobile and being used in a fast-charging and low-temperature environment with high efficiency.
[ second group of comparisons ]
a. Example 3
Preparation of positive electrode sheet: 96.5wt% of mixed active material, 1.7wt% of PVDF, 0.7wt% of SP and 1.1wt% of MWCNT are adopted, and NMP is taken as a solvent; wherein, based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material, the lithium ion battery has a matched working voltage interval and voltage platform, and the lithium ion battery adopts the following materials 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2; uniformly stirring the raw materials, coating the raw materials on the surface of a 13 mu m carbon-coated aluminum foil of a positive current collector, baking at 85 ℃, rolling, die cutting, and compacting to 2.4g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
Preparation of a negative electrode sheet: homogenizing 94wt% of anode active material hard carbon, 2wt% of SP, 2.8wt% of SBR and 1.2wt% of CMC under the condition of taking deionized water as a solvent, coating the slurry on a 6 mu m copper foil, baking at 85 ℃, rolling, die-cutting and compacting to 0.92g/m 3 Baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing; wherein, the content of the negative electrode active material is 1.08, which is the coating surface density, the negative electrode reversible gram capacity/(the content of the mixed active material is the coating surface density, and the positive electrode reversible gram capacity).
Regarding the electrolyte, an organic solvent, an inorganic salt, and an additive are included; wherein the inorganic salt adopts 1mol/L LiPF 6 Organic solvent, inorganic saltAnd the molar ratio of the additive is 4.5:4.5:1.
regarding the separator, polypropylene+Al is used for separating the positive electrode plate from the negative electrode plate 2 O 3 And (3) coating.
b. Example 4
This example 4 differs from example 3 in the preparation of the positive electrode sheet; the method is based on that a high nickel positive electrode material and a ferric sodium sulfate positive electrode material have a matched working voltage interval and voltage platform, and adopts LiNi 0.5 Co 0.2 Mn 0.3 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2.
in a second set of comparisons, example 3 and example 4 are directed to the preparation of lithium sodium hybrid ion batteries, the relevant parameters are as follows:
| second group of | Mixed active materials | Mass ratio | Negative electrode active material |
| Example 3 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Hard carbon |
| Example 4 | LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Hard carbon |
As shown in fig. 6, as can be seen from comparison in the second comparison, firstly, the high-nickel positive electrode material and the sodium iron sulfate positive electrode material are mixed, and as the high-nickel positive electrode material and the sodium iron sulfate positive electrode material have a matched working voltage interval and a voltage platform, the high-nickel positive electrode material and the sodium iron sulfate positive electrode material are mixed according to a certain mass ratio to obtain a mixed active material, so that the prepared lithium-sodium mixed ion battery ensures high working voltage and energy density; secondly, the higher the Ni content is, the further the working voltage of the lithium-sodium mixed ion battery is improved, and the energy density is further increased.
[ third group comparison ]
a. Example 5
Preparation of positive electrode sheet: 96.5wt% of mixed active material, 1.7wt% of PVDF, 0.7wt% of SP and 1.1wt% of MWCNT are adopted, and NMP is taken as a solvent; wherein, based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material, the lithium ion battery has a matched working voltage interval and voltage platform, and the lithium ion battery adopts the following materials 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2, the sodium-iron ratio of the ferric sodium sulfate anode material is 1.5; uniformly stirring the raw materials, coating the raw materials on the surface of a 13 mu m carbon-coated aluminum foil of a positive current collector, baking at 85 ℃, rolling, die cutting, and compacting to 2.4g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
Regarding the negative electrode sheet, lithium metal is used; the lithium metal cathode has lower oxidation-reduction potential and higher specific charge-discharge capacity.
Regarding the electrolyte, an organic solvent, an inorganic salt, and an additive are included; wherein the inorganic salt adopts 1mol/L LiPF 6 The molar ratio of the organic solvent, the inorganic salt and the additive is 4.5:4.5:1.
regarding the separator, polypropylene+Al is used for separating the positive electrode plate from the negative electrode plate 2 O 3 And (3) coating.
b. Example 6
The difference between the example 6 and the example 5 is that the preparation of the positive electrode sheet is based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material with a matched working voltage interval and voltage platform, and the LiNi is adopted 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.3 Fe(SO 4 ) 1.65 As a mixed active material, the sodium-iron ratio of the sodium iron sulfate positive electrode material was 1.3.
In a third set of comparisons, example 5 and example 6 are directed to the preparation of lithium sodium hybrid ion batteries, the relevant parameters are as follows:
| third group of | Mixed active materials | Mass ratio | Sodium to iron ratio | Negative electrode material |
| Example 5 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | 1.5 | Lithium metal |
| Example 6 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 （NCM811) and Na 1.3 Fe(SO 4 ) 1.65 | 8：2 | 1.3 | Lithium metal |
As shown in fig. 7, in the third comparison, it is known that the sodium-iron ratio determines the electrochemical performance of the sodium-iron sulfate positive electrode material, so as to determine the working performance of the lithium-sodium mixed ion battery, and the performance of the lithium-sodium mixed ion battery can be regulated and controlled by adjusting the sodium-iron ratio of the sodium-iron sulfate positive electrode material.
[ fourth group comparison ]
a. Example 7
Preparation of positive electrode sheet: 96.5wt% of mixed active material, 1.7wt% of PVDF, 0.7wt% of SP and 1.1wt% of MWCNT are adopted, and NMP is taken as a solvent; wherein, based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material, the lithium ion battery has a matched working voltage interval and voltage platform, and the lithium ion battery adopts the following materials 0.5 Co 0.2 Mn 0.3 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2; uniformly stirring the raw materials, coating the raw materials on the surface of a 13 mu m carbon-coated aluminum foil of a positive current collector, baking at 85 ℃, rolling, die cutting, and compacting to 2.4g/m 3 And (3) baking the pole piece for 12 hours at 100 ℃ after die cutting and brushing.
Regarding the negative electrode sheet, lithium metal is used; the lithium metal cathode has lower oxidation-reduction potential and higher specific charge-discharge capacity.
Regarding the electrolyte, an organic solvent, an inorganic salt, and an additive are included; wherein the inorganic salt adopts 1mol/L LiPF 6 The molar ratio of the organic solvent, the inorganic salt and the additive is 4.5:4.5:1.
regarding the separator, polypropylene and Al are used for separating the positive electrode plate from the negative electrode plate 2 O 3 。
b. Example 8
The difference between the example 8 and the example 7 is that the preparation of the positive electrode sheet is based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material with a matched working voltage interval and voltage platform, and the LiNi is adopted 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2.
c. example 9
The difference between the example 9 and the example 7 is that the preparation of the positive electrode sheet is based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material with a matched working voltage interval and voltage platform, and LiNiO is adopted 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 8:2.
d. example 10
The difference between the embodiment 10 and the embodiment 7 is that the preparation of the positive electrode plate is based on the high nickel positive electrode material and the ferric sodium sulfate positive electrode material, which have a matched working voltage interval and voltage platform, and the LiNi is adopted 0.8 Co 0.1 Mn 0.1 O 2 Na (sodium carbonate) 1.5 Fe(SO 4 ) 1.75 As a mixed active material, the mass ratio was 5:5.
in a fourth set of comparisons, examples 7, 8, 9, 10 are directed to the preparation of lithium sodium hybrid ion batteries, the relevant parameters are as follows:
| fourth group | Mixed active materials | Mass ratio | Negative electrode material |
| Example 7 | LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Lithium metal |
| Example 8 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Lithium metal |
| Example 9 | LiNiO 2 (LNO) and Na 1.5 Fe(SO 4 ) 1.75 | 8：2 | Lithium metal |
| Example 10 | LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) and Na 1.5 Fe(SO 4 ) 1.75 | 5：5 | Lithium metal |
As shown in fig. 8, in combination with the fourth comparison and the second comparison, the performance of the whole lithium-sodium mixed ion battery can be based on the traditional system using hard carbon as the negative electrode material, the system using lithium metal as the negative electrode material, and the energy density can be further improved; next, comparing example 7, example 8, example 9 alone in the fourth set of comparisons, it can be seen that the mixing of sodium iron sulfate can be adapted to all high nickel positive electrode materials based on the performance of the lithium sodium mixed ion battery; meanwhile, the higher the Ni content, the higher the gram capacity, the working voltage and the energy density of the lithium-sodium mixed ion battery, so that the positive electrode material of the pure nickel has an industrialized application prospect. Furthermore, as can be seen from comparing example 8 with example 10 in the fourth comparison, the performance of the entire lithium-sodium mixed ion battery system can be regulated and controlled by regulating and controlling the mixing ratio of the high nickel positive electrode material and the ferric sodium sulfate positive electrode material, and the performance can be reasonably regulated and controlled according to the practical application scene.
In summary, the factors affecting the performance of the lithium-sodium mixed ion battery mainly include: the method comprises the steps of selecting and proportioning positive electrode materials, proportioning components of high-nickel positive electrode materials, sodium-iron ratio of sodium ferric sulfate positive electrode materials, mass ratio of sodium ferric sulfate positive electrode materials and the like; in the invention, the molecular formula of the adopted high nickel positive electrode material is LiNi 1-x TM x O 2 Wherein x is more than or equal to 0 and less than or equal to 0.5, and TM is one or a combination of more of Co, mn, al and Fe; the molecular formula of the ferric sodium sulfate positive electrode material is Na m Fe(SO 4 ) n Wherein n= (m+2)/2,1.0 is less than or equal to m and less than or equal to 3.0. The ferric sodium sulfate anode material and the high-nickel anode material are mixed, so that the high working voltage and the energy density of the lithium sodium mixed ion battery are ensured, and the high-rate, long-cycle and low-temperature working performance of the lithium sodium mixed ion battery is improved; the Qwt percent of the ferric sodium sulfate anode material has great influence on the performance of the lithium-sodium mixed ion battery, Q and x are positively correlated, and Q epsilon [0.1, 99.9]]In the application scene, the performance of the lithium-sodium mixed ion battery system can be regulated and controlled by reasonably regulating and controlling the mixing proportion.
In the above embodiments, the following manner may be adopted regarding the selection of the material:
firstly, the conductive agent in the positive electrode material and the negative electrode material adopts any one or a combination of at least two of conductive carbon black, acetylene black, graphite, graphene, carbon nano tubes or carbon nano fibers;
secondly, the binding agent in the positive electrode material and the negative electrode material adopts any one or a combination of at least two of polyvinylidene fluoride, modified polyvinylidene fluoride, polyvinylidene chloride, modified polyvinylidene chloride, polyvinylidene fluoride copolymer, polyvinylidene chloride copolymer, polymethyl methacrylate or styrene butadiene rubber;
third, the inorganic salt in the electrolyte adopts lithium salt or sodium salt, including LiPF 6 、LiBF 4 、LiClO 4 、LiAsF 6 、LiN(CF 3 SO 2 ) 2 、LiC(CF 3 SO 2 ) 3 、LiB(C 2 O 4 ) 2 、LiBOB、NaClO 4 、NaPF 6 、Na[(FSO 2 ) 2 N]One or more of the following;
fourth, the positive current collector adopts any one of aluminum foil and carbon-coated aluminum foil, and porous aluminum foil;
fifthly, the negative current collector adopts copper foil;
sixthly, the diaphragm adopts polyethylene, polypropylene, polyethylene+polypropylene, polyethylene+Al 2 O 3 Coating, polypropylene+Al 2 O 3 Any one of the coatings.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the same according to the content of the present invention, and are not intended to limit the scope of the present invention. It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present invention be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (7)
1. A hybrid active material characterized by: comprises a high nickel anode material and a ferric sodium sulfate anode material, and is formed by mixing;
wherein the molecular formula of the high nickel positive electrode material is LiNi 1-x TM x O 2 Wherein x is more than or equal to 0 and less than or equal to 0.5, and TM is one or more of Co, mn, al and FeCombining;
the molecular formula of the sodium iron sulfate positive electrode material is Na m Fe(SO 4 ) n Wherein n= (m+2)/2,1.0 is less than or equal to m and less than or equal to 3.0;
the mass percentage of the ferric sodium sulfate positive electrode material accounting for the mixed active material is Qwt percent, Q and x are positively correlated, and Q epsilon [0.1, 99.9].
2. The utility model provides a lithium sodium mixes uses ion battery, includes positive pole piece, negative pole piece, electrolyte and diaphragm, its characterized in that: the positive electrode plate comprises a positive electrode current collector and a positive electrode material formed on the positive electrode current collector; the positive electrode material comprises the mixed active material of claim 1, a conductive agent and a binder;
the negative electrode plate adopts a lithium metal negative electrode or adopts a combination of a negative electrode current collector and a negative electrode material, wherein the negative electrode material is formed on the negative electrode current collector and comprises a negative electrode active material, a conductive agent and a binder;
the electrolyte comprises an organic solvent, inorganic salt and an additive;
the separator separates the positive pole piece from the negative pole piece.
3. The lithium-sodium mixed ion battery of claim 2, wherein: in the positive electrode material, the mixed active material has 80 to 99.8 parts by weight, the conductive agent has 0.1 to 10 parts by weight, and the binder has 0.1 to 10 parts by weight.
4. The lithium-sodium mixed ion battery of claim 2, wherein: the compaction density of the positive pole piece is 1.5g/cm 3 ～3.5g/cm 3 The compacted density of the negative electrode plate is 0.5g/cm 3 ～1.5g/cm 3 。
5. The lithium-sodium mixed ion battery of claim 2, wherein: regarding the negative pole piece and the positive pole piece, 0.95-0% of the total weight of the battery is reducedN W *N A *N g ）/（P W *P A *P g ) Less than or equal to 1.36, wherein:
N W 、P W the content of the negative electrode active material and the content of the mixed active material are respectively;
N A 、P A the coating surface density of the anode material and the coating surface density of the cathode material are respectively;
N g 、P g the negative electrode reversible gram capacity and the positive electrode reversible gram capacity are respectively.
6. The lithium-sodium mixed ion battery of claim 2, wherein: according to parts by weight, in the anode material, 80-98 parts of anode active material, 1-10 parts of conductive agent and 1-10 parts of binder.
7. The lithium-sodium mixed ion battery of claim 2, wherein: the conductive agent in the positive electrode material and the negative electrode material adopts any one or a combination of at least two of conductive carbon black, graphite, graphene, carbon nano tubes or carbon nano fibers; and/or the number of the groups of groups,
the binder in the positive electrode material and the negative electrode material adopts any one or a combination of at least two of polyvinylidene fluoride, modified polyvinylidene fluoride, polyvinylidene chloride, modified polyvinylidene chloride, polyvinylidene fluoride copolymer, polyvinylidene chloride copolymer, polymethyl methacrylate or styrene butadiene rubber; and/or the number of the groups of groups,
the inorganic salt in the electrolyte adopts LiPF 6 、LiBF 4 、LiClO 4 、LiAsF 6 、LiN(CF 3 SO 2 ) 2 、LiC(CF 3 SO 2 ) 3 、LiB(C 2 O 4 ) 2 、LiBOB、NaClO 4 、NaPF 6 、Na[(FSO 2 ) 2 N]One or more of the following; the concentration of the inorganic salt is 0.5-2 mol/L; and/or the number of the groups of groups,
the positive current collector adopts aluminum foil; and/or the number of the groups of groups,
the negative current collector adopts copper foil; and/or the number of the groups of groups,
the diaphragm adopts polyethylene, polypropylene, polyethylene+polypropylene, polyethylene+Al 2 O 3 Coating, polypropylene+Al 2 O 3 Any one of the coatings.
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