Patent Application
20250105282
The present disclosure relates to the field of battery technologies, and in particular, to a positive electrode material, a preparation method of a positive electrode material, a positive electrode plate, and a battery.
With the development of battery technologies, achieving higher capacities under the condition of stable structures of positive electrode materials has become an urgent need. Currently, a charge cut-off voltage has transitioned from original 4.2 V or 4.3 V to current 4.45 V or 4.48 V, and will eventually develop toward 4.5 V, 4.6 V, or even higher.
However, an existing positive electrode material undergoes a severe irreversible phase transition when the charge cut-off voltage exceeds 4.5 V. For example, at 4.55 V, the positive electrode material undergoes a phase transition from an 03 phase to an H1-3 phase, and at a higher voltage, undergoes a phase transition from the H1-3 phase to an 01 phase. Such an irreversible phase transition causes a structure of the positive electrode material to because extremely unstable at a high voltage, leading to severe contraction of a crystal structure. This results in cracking or even destruction of positive electrode material particles, consequently causing problems such as rapid capacity fading and a rapid cycling performance drop. It can be learned that a positive electrode material in the prior art has a problem of low capacity.
Although doping and coating a positive electrode material suppress or mitigate harmful effects of these phase transitions to an extent, a capacity loss is caused.
The present disclosure provides a positive electrode material, a preparation method of a positive electrode material, a positive electrode plate, and a battery, to solve a problem of low capacity of a positive electrode material in the prior art.
The present disclosure provides a positive electrode material. The positive electrode material includes a sodium-containing oxide, an angle range of a first characteristic peak of the sodium-containing oxide is less than an angle range of a second characteristic peak, the first characteristic peak is a characteristic peak of the sodium-containing oxide at an initial voltage, the second characteristic peak is a characteristic peak of the sodium-containing oxide at a cut-off voltage, and a chemical formula of the sodium-containing oxide is LixNa1-x Co1-z MzO2.
M includes a metal element or a non-metal element, 0.7<x<1, and 0.001<z<0.03.
The present disclosure further provides a preparation method of a positive electrode material, used for preparing the positive electrode material describe above. The method includes:
The present disclosure further provides a positive electrode plate, including a current collector and a coating layer disposed on a surface of one or both sides of the current collector, where the coating layer includes the positive electrode material in the present disclosure and/or a positive electrode material prepared by using the preparation method of a positive electrode material in the present disclosure.
The present disclosure further provides a battery, including a positive electrode plate and a negative electrode plate, where the positive electrode plate includes the positive electrode material in the present disclosure and/or a positive electrode material prepared by using the preparation method of a positive electrode material in the present disclosure.
In the present disclosure, during a phase transition process of the sodium-containing oxide from the initial voltage to the cut-off voltage, the first characteristic peak and the second characteristic peak are formed. The angle range of the first characteristic peak is less than the angle range of the second characteristic peak. In this way, the sodium-containing oxide can release more lithium ions at a same voltage, thereby improving a capacity of the positive electrode material, and improving rate performance and cycling performance of the positive electrode material.
To describe technical solutions in embodiments of the present disclosure more clearly, the following briefly describes the accompanying drawings required for describing embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some of embodiments of the present disclosure, and persons of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.
The following clearly describes the technical solutions in embodiments of the present disclosure with reference to the accompanying drawings in embodiments of the present disclosure.
Apparently, the described embodiments are some but not all of embodiments of the present disclosure. All other embodiments obtained by persons of ordinary skill in the art based on embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.
In the specification and claims of the present disclosure, the terms “first”, “second”, and the like are intended to distinguish between similar objects but do not indicate a particular order or a sequence. It should be understood that the structures used in this way are interchangeable under appropriate circumstances so that embodiments of the present disclosure can be implemented in an order other than those illustrated or described herein, and the objects distinguished by “first”, “second”, and the like are generally of a same type. A quantity of the objects is not limited. For example, a first object may be one or more objects. In addition, “and/or” in the specification and claims represents at least one of the associated objects, and the character “/” generally indicates that the associated objects are in an “or” relationship.
The present disclosure provides a positive electrode material, as shown in
M includes a metal element or a non-metal element, 0.7<x<1 (for example, x is 0.71, 0.75, 0.8, 0.85, 0.9, 0.95, or 0.99), and 0.001<z<0.03 (for example, z is 0.0015, 0.005, 0.01, 0.015, 0.02, 0.025, or 0.029).
In the chemical formula LixNa1-xCo1-zMzO2, when M includes a plurality of elements (≥2), z is a sum of atom quantities of the plurality of elements. For example, when M is Al and Mg, a sum of atom quantities of Al and Mg is z.
In the present disclosure, during a phase transition process of the sodium-containing oxide from the initial voltage to the cut-off voltage, the first characteristic peak and the second characteristic peak are formed. The first characteristic peak is a characteristic peak of the sodium-containing oxide at the initial voltage (3 V), and the second characteristic peak is a characteristic peak of the sodium-containing oxide at the cut-off voltage (4.5 V). The angle range of the first characteristic peak is less than the angle range of the second characteristic peak. In this way, the sodium-containing oxide can release more lithium ions at a same voltage, thereby improving a capacity of the positive electrode material, and improving rate performance and cycling performance of the positive electrode material.
Specifically, a chemical formula of the sodium-containing oxide may be LixNa1-xCo1-zMzO2. In an in-situ X-ray diffraction (XRD) pattern during a charge and discharge process of 3-4.5 V, as shown in
For example, as shown in
In one example, the positive electrode material provided in the present disclosure can achieve a gram capacity of 202 mAh/g at 4.5 V, which is much higher than the conventional commercial lithium cobalt oxide material (186 mAh/g) at the same voltage.
In one example, during a charge and discharge process from the initial voltage to the cut-off voltage, the sodium-containing oxide includes a plurality of phase transitions, and the plurality of phase transitions are reversible phase transitions.
In the present disclosure, it can be learned from an in-situ XRD (as shown in
Each phase transition process in the plurality of phase transitions includes an equilibrium potential. In other words, a charge and discharge test was conducted on sodium-containing oxide LixNa1-xCo1-zMzO2, where a test result was shown in
In one example, a phase layered structure of the sodium-containing oxide includes a plurality of stacked repeating units, each of the repeating units presents a layered structure in which a first transition metal layer, a lithium oxygen layer, and a second transition metal layer are stacked, and transition metal and lithium atoms respectively occupy octahedral sites. A morphology of the sodium-containing oxide may be polycrystalline or monocrystalline.
Specifically, the LixNa1-xCo1-zMzO2 material exhibits four reversible phase transitions in the in-situ XRD. The first phase transition is during charging from 3.7 V to 3.8 V, where a phase transition in which Li atoms in the material transition from octahedral sites to tetrahedral sites. The second phase transition is during charging from 4.0 V to 4.15 V, where continuous extraction of Li leads to a change in lattice parameters, resulting in a phase transition. The third phase transition is during charging from 4.15 V to 4.25 V, where Li reoccupies the octahedral sites and the lithium-cobalt layer undergoes interlayer sliding. The fourth phase transition is during charging from 4.4 V to 4.5 V, where a structural unit transitions from an alternating arrangement of six lithium-cobalt metal layers to an arrangement of two lithium-cobalt metal layers. During a discharge process, an angle change is consistent with that of the charge process, and the phase transition is completely reversible. After a complete charge and discharge process, the LixNa1-xCo1-zMzO2 material can completely return to its original phase structure, reflecting good kinetic stability of the material during the charge and discharge process. The in-situ XRD shows that all phase transitions of the material between 3 V and 4.5 V are reversible phase transitions, and the material can maintain good structural stability during the charge and discharge process. The material has a plurality of reversible phase transitions at less than 4.6 V, and therefore can not only achieve a high capacity but also have good cycling performance. In addition, a structure of the material has a larger interlayer electrostatic repulsion due to coplanarity of a LiO6 layer and a CoO6 layer, so as to achieve a larger transition metal interlayer spacing than the lithium cobalt oxide in the prior art. Therefore, this is more conducive to rapid diffusion of Li ions between the layers, thereby achieving higher rate performance and improving a capacity of the positive electrode material.
In one example, during the charge and discharge process from the initial voltage to the cut-off voltage, at a first voltage range, the sodium-containing oxide compound coexists as a first phase and a second phase; at a second voltage range, the sodium-containing oxide compound coexists as a third phase and a fourth phase; and at a third voltage range, the sodium-containing oxide compound coexists as a fifth phase and a sixth phase. The first voltage range is from 3.7 V to 3.8 V (for example, is 3.71V, 3.73V, 3.75V, 3.78V or 3.8V); the second voltage range is from 4.15 V to 4.25 V (for example, is 4.15V, 4.18V, 4.2V, 4.23V or 4.25V); and the third voltage range is from 4.4 V to 4.5 V (for example, is 4.41V, 4.43V, 4.45V, 4.48V or 4.5V).
In one example, during the charge process of the LixNa1-xCo1-zMzO2 material, the first phase transition occurs during charging from 3 V to the first voltage range (which may be, for example, 3.7 V to 3.8 V), and two peaks coexist within a range of 17.6° to 18.7° (for example, 17.6°, 17.7°, 17.8°, 17.9°, 18°, 18.1°, 18.2°, 18.3°, 18.4°, 18.5°, 18.6°, or 18.7°) in an XRD spectrum, that is, the first phase and the second phase coexist. The first phase may be a left peak at 17.6° to 18.2° (for example, 17.6°, 17.7°, 17.8°, 17.9°, 18°, 18.1°, 18.2°, or 18.7°), and the second phase may be a right peak at 18.4° to 18.7° (for example, 18.4°, 18.5°, 18.6°, or 18.7°), and as the charge process progresses, the left peak gradually strengthens, and the right peak gradually weakens until it disappears.
During continued charging of 4.0 V to 4.15 V, the enhanced left peak slowly shifts to the left, and the angle range may be from 17.7° to 180 (for example, 17.7°, 17.8°, 17.9°, or 18°), during which the second phase transition reaction occurs.
During continued charging to the second voltage range (which may be, for example, 4.15 V to 4.25 V), the third phase transition occurs, during which two peaks coexist, that is, the third phase and the fourth phase coexist. The third phase may be a left peak at 17.6° to 18.1° (for example, 17.6°, 17.7°, 17.8°, 17.9°, 18° or 18.1°), and the fourth phase may be a right peak at 18.0° to 18.7°. The left peak gradually weakens until it disappears, and the right peak gradually strengthens. A peak position ranges from 17.6° to 18.7° (for example, 17.6°, 17.7°, 17.8°, 17.9°, 18°, 18.10, 18.2°, 18.3°, 18.4°, 18.5°, 18.6°, or 18.7°).
During continued charging to the third voltage range (which may be, for example, 4.4 V to 4.5 V), the fourth phase transition occurs, and two peaks also coexist, that is, the fifth phase and the sixth phase coexist. The fifth phase may be a left peak located at 180 to 18.6° (for example, 18°, 18.10, 18.2°, 18.3°, 18.4°, 18.5°, or 18.6°), and the sixth phase may be a right peak located at 18.7° to 19.5° (for example, 18.7°, 18.8°, 18.9°, 19°, 19.10, 19.2°, 19.3°, 19.4° or 19.5°). The left peak gradually weakens until it disappears, and the right peak gradually strengthens. A peak position change range is from 180 to 19.5° (for example, 18°, 18.1°, 18.2°, 18.3°, 18.4°, 18.5°, 18.6°, 18.7°, 18.8°, 18.9°, 19°, 19.1°, 19.2°, 19.3°, 19.4° or 19.5°). This is completely reversible during the discharge process.
In comparison with in-situ XRD of a current commercial lithium cobalt oxide material, a result of an in-situ XRD test of the commercial lithium cobalt oxide during a charge and discharge process of 3 V to 4.5 V shows (as shown in
M includes at least one element of Al, Mg, Ti, Zr, Mn, Ni, B, P, Y, Te, Nb, W, K, or La.
It should be noted that the M element includes the foregoing metal element or non-metal element, and may also be another element that can form a covalent bond with an oxygen atom and embed into the LixNa1-xCo1-zMzO2 lattice, such as a lanthanide element La/Y, and a same technical effect can be achieved. Details are not described herein.
A median particle size of the sodium-containing oxide may range from 3 m to 30 m (for example, is 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm).
A specific surface area of the sodium-containing oxide may range from 0.2 m2/g to 1 m2/g (for example, is 0.2 m2/g, 0.3 m2/g, 0.4 m2/g, 0.5 m2/g, 0.6 m2/g, 0.7 m2/g, 0.8 m2/g, 0.9 m2/g, or 1 m2/g).
It should be noted that, in a case that the initial voltage is charged to a cut-off voltage of higher than 4.6 V for the sodium-containing oxide, phase transitions are also completely reversible. After a complete charge and discharge process, the sodium-containing oxide LixNa1-x Co1-z MzO2 can completely return to its original phase structure, and kinetic stability is good during the charge and discharge process.
The following describes, based on a plurality of groups of experiments, effects of batteries prepared by using the positive electrode material provided in the present disclosure.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.97Na0.03Co0.99Al0.01O2. First, cobalt nitrate and aluminum sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Al of 0.99:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 900° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.99Al0.01)3O4 material. Then, the (Co0.99Al0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.76:0.99, and sintered in an oxygen atmosphere at 950° C. for 36 hours to obtain Na0.76Co0.99Al0.01O2. Then the Na0.76Co0.99Al0.01O2 and LiCl were mixed and heated at 300° C. to melt to finally obtain Li0.97Na0.03Co0.99Al0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.95Na0.05Co0.99Al0.01O2. First, cobalt nitrate and aluminum sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Al of 0.99:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 900° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.99Al0.01)3O4 material. Then, the (Co0.99Al0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.74:0.99, and sintered in an oxygen atmosphere at 850° C. for 36 hours to obtain Na0.74Co0.99Al0.01O2. Then the Na0.74Co0.99Al0.01O2 and LiCl were mixed with Li/Na being 7, and heated at 300° C. to melt to finally obtain Li0.95Na0.05Co0.99Al0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.93Na0.07Co0.99Al0.01O2. First, cobalt nitrate and aluminum sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Al of 0.99:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 900° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.99Al0.01)3O4 material. Then, the (Co0.99Al0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.72:0.99, and sintered in an oxygen atmosphere at 750° C. for 36 hours to obtain Na0.72Co0.99Al0.01O2. Then the Na0.72Co0.99Al0.01O2 and LiCl were mixed with Li/Na being 5, and heated at 300° C. to melt to finally obtain Li0.93Na0.07Co0.99Al0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.92Na0.05Co0.99Mg0.01O2. First, cobalt nitrate and magnesium sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Mg of 0.99:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 900° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.99Mg0.01)3O4 material. Then, the (Co0.99Mg0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.70:0.99, and sintered in an oxygen atmosphere at 750° C. for 36 hours to obtain Na0.70Co0.99Mg0.01O2. Then the Na0.70Co0.99Mg0.01O2 and LiCl were mixed with Li/Na being 7, and heated at 300° C. to melt to finally obtain Li0.92Na0.08Co0.99Mg0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.95Na0.05Co0.99Ni0.01O2. First, cobalt nitrate and nickel sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Ni of 0.99:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 800° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.99Ni0.01)3O4 material. Then, the (Co0.99Ni0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.72:0.99, and sintered in an oxygen atmosphere at 800° C. for 36 hours to obtain Na0.72Co0.99Ni0.01O2. Then the Na0.72Co0.99Ni0.01O2 and LiCl were mixed with Li/Na being 10, and heated at 300° C. to melt to finally obtain Li0.95Na0.05Co0.99Ni0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.95Na0.05Co0.98Al0.01Mg0.01O2. First, cobalt nitrate, aluminum sulfate, and magnesium sulfate were added to a solvent (such as deionized water) at a molar ratio of Co to Al to Mg of 1.98:0.01:0.01, and then 0.05 mol/L sodium hydroxide and ammonia water were added to adjust the pH to 6-10 so that the mixture formed a coprecipitate. The precipitate was sintered at 800° C. for 20 hours in air atmosphere, and then the resulting product was processed by grinding and sieving to obtain a (Co0.98Al0.01Mg0.01)3O4 material. Then, the (Co0.98Al0.01Mg0.01)3O4 and Na2CO3 were uniformly mixed at a molar ratio of Na to Co of 0.72:1, and sintered in an oxygen atmosphere at 800° C. for 36 hours to obtain Na0.72Co0.98Al0.01Mg0.01O2. Then the Na0.72Co0.98Al0.01Mg0.01O2 and LiCl were mixed with Li/Na being 10, and heated at 300° C. to melt to finally obtain Li0.95Na0.05Co0.98Al0.01Mg0.01O2.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.97Na0.03Co0.98Al0.01Ni0.01O2. A preparation process of the sodium-containing oxide in Example 7 was the same as that in Example 1, except that the Ni element was added according to a molar ratio during coprecipitation.
Preparation of sodium-containing oxide in a positive electrode material: A chemical formula of the sodium-containing oxide may be Li0.97Na0.03Co0.98Al0.01Mg0.005Ni0.005O2. A preparation process of the sodium-containing oxide in Example 8 was the same as that in Example 1, except that the Mg element and the Ni element were added according to a molar ratio during coprecipitation.
A commercial lithium cobalt oxide positive electrode material was prepared by a conventional synthesis method. The synthesis method was as follows: cobalt sulfate and aluminum sulfate were added to deionized water at a molar ratio of 0.99:0.01, and sodium carbonate and ammonia water were added as a precipitating agent and a complexing agent respectively to adjust the pH to 7-8 for precipitation. The precipitate was processed by sintering and grinding to obtain (Co0.99Al0.01)3O4, and then was mixed with Li2CO3 according to a molar ratio of Li/Co of 1.01. The mixture was sintered at 900° C. in air for 12 hours to finally obtain a lithium cobalt oxide positive electrode material with a chemical formula of LiCo0.99Al0.01O2.
A preparation method of a positive electrode material in Comparative Example 2 was the same as that in Comparative Example 1, except that the Mg element was added according to a molar ratio during coprecipitation, to finally obtain a lithium cobalt oxide positive electrode material with a chemical formula of LiCo0.98Al0.01Mg0.01O2.
A preparation method of a positive electrode material in Comparative Example 3 was the same as that in Comparative Example 1, except that the Mg element was added according to a molar ratio during coprecipitation, and the Ti element was added according to a molar ratio during sintering, to finally obtain a lithium cobalt oxide positive electrode material with a chemical formula of LiCo0.97Al0.01Mg0.01Ti0.01O2.
A preparation method of a positive electrode material in Comparative Example 4 is the same as that in Comparative Example 1, except that Mg was added according to a molar ratio during coprecipitation, and Ti and Zr elements were added according to a molar ratio during sintering, to finally obtain a lithium cobalt oxide positive electrode material with a chemical formula of LiCo0.96Al0.01Mg0.01Ti0.01Zr0.01O2.
In Examples 1 to 8 and Comparative Examples 1 to 4, positive electrode plates were prepared in a same manner and assembled into lithium batteries. The lithium batteries were subjected to electrochemical tests. Electrochemical performance test results are shown below in Table 1.
It can be learned, from the table above, that a positive electrode material including LixNa1-xCo1-z MzO2 provided in the present disclosure has a higher capacity and better rate and cycling performance at a same voltage than conventional commercial high-voltage lithium cobalt oxide.
Refer to
In this step, the cobalt salt includes but is not limited to cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, and the like, and the M salt may be nitrate, sulfate, oxalate, acetate, and the like. The cobalt salt and the M salt may be added at a preset ratio to deionized water, and then a precipitant and a complexing agent accounting for a total content ranging from 0.01 mol/L to 2 mol/L (for example, is 0.01 mol/L, 0.05 mol/L, 0.1 mol/L, 0.5 mol/L, 1 mol/L, 1.5 mol/L, or 2 mol/L) may be added, where the precipitating agent may be sodium hydroxide, and the complexing agent may be ammonia water, so that a molar ratio of the complexing agent to the precipitant is 0.1:2, the pH is adjusted to 6-10, and the mixture forms a coprecipitate.
Step 502: adding a sodium-containing salt to the coprecipitate to obtain an intermediate product.
In this step, the sodium-containing salt may be sodium carbonate, and a molar ratio of Co in the coprecipitate to Na in the sodium-containing salt of n:1 (0.69<n<0.78) is used for even mixing, the mixture is sintered in an oxygen atmosphere at 700° C. to 1000° C. (for example, at 700° C., 750° C., 800° C., 850° C., 900° C., 950° C., or 1000° C.) for 24 hours to 36 hours (for example, is 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, or 36 hours) to obtain the intermediate product.
Step 503: adding a lithium-containing salt to the intermediate product to obtain a precursor.
In this step, the intermediate product is mixed with a lithium-containing salt, and then heated to melt, where it is ensured that a molar ratio of Li/Na is 2:10, and the lithium salt may be selected from one or more of lithium chloride, lithium bromide, lithium acetate, lithium carbonate, or lithium hydroxide. Finally, a precursor is obtained after heating at 100° C. to 300° C. (for example, is 100° C., 150° C., 200° C., 250° C., or 300° C.). The precursor may sodium-containing oxide with a chemical formula of LixNa1-xCo1-zMzO2.
Step 504: obtaining the positive electrode material based on the precursor.
In this step, the positive electrode material is mixed with a conductive agent, a binder, and the like to obtain a positive electrode slurry.
In the present disclosure, the sodium-containing oxide LixNa1-xCo1-zMzO2 can maintain good structural stability during a charge and discharge process, and has a plurality of reversible phase transitions, so that the sodium-containing oxide can not only achieve a high capacity but also have good cycling performance. In addition, a structure of the material has a larger interlayer electrostatic repulsion due to coplanarity of a LiO6 layer and a CoO6 layer, so as to achieve a larger transition metal interlayer spacing. Therefore, this is more conducive to rapid diffusion of Li ions between the layers, thereby achieving higher rate performance and improving a gram capacity of the positive electrode material.
In one example, a molar ratio between Co and M in the cobalt salt solution and the M salt solution is (1-z):z, and the coprecipitate includes (Co1-zMz)3O4, where 0.001<z<0.03 (for example, z is 0.0015, 0.005, 0.01, 0.015, 0.02, 0.025, or 0.029); the intermediate product includes NamCo1-zMzO2, where 0.65<m<1 (for example, x is 0.66, 0.68, 0.7, 0.71, 0.75, 0.8, 0.85, 0.9, 0.95, or 0.99); and the precursor includes LixNa1-xCo1-zMzO2, where 0.70<x<1 (for example, x is 0.71, 0.75, 0.8, 0.85, 0.9, 0.95, or 0.99).
The cobalt salt and the M salt may be at a molar ratio of Co to M (1-z):z, and are added to deionized water, and then a precipitant and a complexing agent accounting for a total content ranging from 0.01 mol/L to 2 mol/L are added to obtain a coprecipitate. The coprecipitate is sintered in an air atmosphere at 300° C. to 900° C. for 10 hours to 20 hours, and the product is processed by grinding and sieving to obtain a (Co1-z Mz)3O4 material, where 0.001<z<0.03, and a median particle size of the (Co1-zMz)3O4 ranges from 3 m to 30 m. Then, the (Co1-zMz)3O4 and Na2CO3 are evenly mixed at a molar ratio of Na to Co of n:1 (0.69<n<0.78), and sintered in an oxygen atmosphere at 700° C. to 1000° C. for 24 hours to 36 hours to obtain NamCo1-zMzO2, where 0.65<m<1. The NamCo1-zMzO2 and the lithium salt are mixed and heated to melt, so as to obtain LixNa1-xCo1-zMzO2. The gram capacity of the positive electrode material is improved by adding the sodium-containing oxide LixNa1-xCo1-zMzO2.
The present disclosure further provides a positive electrode plate, including a current collector and a coating layer disposed on the current collector, where the coating layer includes the positive electrode material in the present disclosure and/or a positive electrode material prepared by using the preparation method of a positive electrode material in the present disclosure.
In one example, the current collector is made of a metal foil.
In one example, the curren collector is made of an aluminum foil.
In one example, a thickness of the aluminum foil ranges from 6 m to 10 m (for example, is 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm).
In one example, the coating layer includes the positive electrode material, and a positive electrode active material in the positive electrode material may include LixNa1-x Co1-z MzO2.
In one example, a press density of the positive electrode plate may range from 3 g/cm3 to 4.5 g/cm3 (for example, is 3 g/cm3, 3.2 g/cm3, 3.5 g/cm3, 3.8 g/cm3, 4 g/cm3, 4.2 g/cm3, or 4.5 g/cm3).
In one example, the coating layer further includes a conductive agent and a binder. The binder may include one or more of polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), water-based acrylic resin, polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), or polyvinyl alcohol (PVA). The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.
In one example, based on a total weight of the coating layer, a weight content of the positive electrode material ranges from 90 wt % to 99 wt %, a weight content of the conductive agent ranges from 0.5 wt % to 5 wt %, and a weight content of the binder ranges from 0.5 wt % to 5 wt %.
Specifically, the positive electrode material, the conductive agent, and the binder are dispersed in a solvent (such as N-methylpyrrolidone, NMP for short) to form a uniform coating layer, and the coating layer is coated on a positive electrode current collector. After drying and rolling processes, the positive electrode plate is obtained. During the charge and discharge process from an initial voltage to a cut-off voltage, the positive electrode material has a plurality of reversible phase transitions. These phase transitions are not only reversible, but also achieve a higher capacity at a lower voltage, thereby increasing a capacity of the positive electrode plate at a same charge cut-off voltage.
The present disclosure further provides a battery, including a positive electrode plate and a negative electrode plate, where the positive electrode plate includes the positive electrode material in the present disclosure and/or a positive electrode material prepared by using the preparation method of a positive electrode material in the present disclosure.
The battery may be a lithium-ion battery.
The battery may be a lithium-ion secondary battery.
It should be noted that the implementations of the embodiment of the positive electrode material described above is also applicable to the embodiment of the battery and a same technical effect can be achieved. Details are not described herein again.
It should be noted that in this specification, the terms “include” and “comprise”, or any of their variants are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements not only includes those elements but also includes other elements that are not expressly listed, or further includes elements inherent to such process, method, article, or apparatus. In absence of more constraints, an element preceded by “includes a . . . ” does not preclude the existence of other identical elements in the process, method, article, or apparatus that includes the element. Furthermore, it should be noted that the scope of the methods and apparatuses in embodiments of the present disclosure is not limited to performing the functions in the order discussed, but may also include performing the functions in a substantially simultaneous manner or in a reverse order depending on the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to some examples may be combined in other examples.
The foregoing describes embodiments of the present disclosure with reference to the accompanying drawings. However, the present disclosure is not limited to these specific embodiments. The specific embodiments are merely illustrative rather than restrictive. Inspired by the present disclosure, persons of ordinary skill in the art may develop many other manners without departing from the principle of the present disclosure and the protection scope of the claims, and all such manners fall within the protection scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211045711.1 | Aug 2022 | CN | national |
The present disclosure is a continuation-in-part of International Application No. PCT/CN2023/110604, filed on Aug. 1, 2023, which claims priority to Chinese Patent Application No. CN202211045711.1, filed on Aug. 30, 2022. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/110604 | Aug 2023 | WO |
| Child | 18974272 | US |
