Lithium ion battery positive pole lithium supplement material, preparation method thereof, positive pole piece and battery
By generating a lithium-rich phase of Li5AlO4 and employing a three-stage gradient sintering process, the problem of irreversible lithium loss during the first charge and discharge of lithium-ion batteries was solved, achieving high energy density and long-term cycle stability. This simplifies the preparation process and reduces energy consumption, making it suitable for the large-scale production of lithium replenishment agents for lithium-ion battery cathodes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2026-03-27
AI Technical Summary
During the first charge and discharge process, existing lithium-ion batteries irreversibly consume a large amount of active lithium due to the formation of a solid electrolyte interface film on the negative electrode surface, resulting in a decrease in the first coulombic efficiency and affecting the battery's energy density and cycle life. Existing positive electrode lithium replenishing agents have problems such as limited lithium replenishing capacity, poor structural stability, complex preparation process, and difficulty in large-scale production.
A lithium-rich phase, Li5AlO4, is generated by reacting transition metal oxides with an excess lithium source. A dense and uniform crystal framework is formed through three-level gradient sintering, which simultaneously provides active lithium and locks the crystal framework, suppressing lattice oxygen release and transition metal dissolution. Spray freezing and vacuum freeze-drying technologies are used to shorten the preparation time, reduce energy consumption, and ensure good compatibility between the material and the cathode material.
It significantly improves the energy density and cycle life of lithium-ion batteries, reduces the first irreversible lithium loss, enhances battery performance consistency and stability, and has a simple process that is easy to scale up for production.
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Figure CN121748583A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a lithium-ion battery positive electrode lithium replenishment agent material, its preparation method, positive electrode sheet and battery. Background Technology
[0002] With the rapid development of electric vehicles, energy storage systems, and portable electronic devices, increasingly higher demands are being placed on the energy density, cycle life, and safety performance of lithium-ion batteries. During the first charge and discharge process of a lithium-ion battery, a solid electrolyte interface film forms on the surface of the negative electrode. This process irreversibly consumes a large amount of active lithium, leading to a decrease in the initial coulombic efficiency, which in turn affects the battery's energy density and cycle life.
[0003] To address the aforementioned issues, existing technologies primarily employ two strategies for lithium replenishment: negative electrode replenishment (e.g., lithium metal foil, lithium powder) and positive electrode replenishment (e.g., lithium-rich materials). However, negative electrode replenishment processes are complex, costly, and pose significant safety risks. While existing positive electrode replenishing agents (such as Li₂MoO₃ and Li₅FeO₄) can compensate for lithium loss during the initial charge-discharge cycle to some extent, they still have the following shortcomings: limited replenishment capacity, making it difficult to meet the demands of high-energy-density batteries; poor structural stability, prone to side reactions leading to gas generation and increased interfacial impedance; complex preparation processes, high sintering temperatures, and high energy consumption, hindering large-scale industrial production; and uneven particle size distribution, resulting in poor compatibility with positive electrode materials and inconsistent battery performance. Furthermore, existing replenishing agent preparation processes using solid-state sintering methods produce materials with large particle sizes, which can affect the stability of the material during cycling when added to the positive electrode material.
[0004] To address the aforementioned shortcomings of existing technologies, this invention aims to provide a high-capacity, high-stability, simple-process, and easily scalable cathode lithium replenishment agent material and its preparation method. By optimizing the preparation process of the lithium replenishment agent, its lithium replenishment capacity and stability are significantly improved, and the initial irreversible capacity loss is reduced, thereby enhancing the energy density and cycle life of lithium-ion batteries. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a lithium-ion battery cathode lithium replenishment material, its preparation method, cathode sheet, and battery. The method involves reacting a transition metal oxide with an excess lithium source to generate a lithium-rich phase, represented by Li5AlO4, with a theoretical lithium replenishment capacity far exceeding that of traditional Li2MoO3. A dense and uniform crystal framework is formed through three-stage gradient sintering, suppressing lattice oxygen release and transition metal dissolution during cycling and reducing side reaction gas generation. By simultaneously amplifying the active lithium supply and locking the crystal framework, the present invention significantly suppresses irreversible lithium loss in the first cycle, thereby simultaneously enhancing the battery's energy density and long-term cycle stability.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing a lithium-ion battery cathode lithium replenishment agent material.
[0008] include:
[0009] The transition metal source and lithium source were mixed according to the molar ratio, a dispersant was added, and the mixture was wet ball milled and dried to obtain material A.
[0010] Material A is diluted and dissolved with deionized water, then spray-frozen to solidify into ice beads and freeze-dried to obtain powder. The powder is then sintered for the first time in an atmosphere and cooled to obtain material B.
[0011] Material B is ground, then sintered a second time in an atmosphere, and cooled to obtain material C;
[0012] The material C is finely ground, sieved, and then sintered a third time in an atmosphere to obtain the lithium supplement Li. x B y O z B is one of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.
[0013] Preferably, the transition metal source is an oxide of one of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and the lithium source is one of lithium carbonate, anhydrous lithium hydroxide, and high-purity LiOH·H2O.
[0014] Preferably, the ice beads have a particle size of 0.001-10 mm, and the freeze-drying pressure is 0.03-300 Pa, but is not limited to the listed values; other unlisted values within this range are also applicable. This solution uses spray freeze-drying combined with vacuum freeze-drying technology to shorten the drying time from the conventional 12 h to 2 h, and directly transforms 0.5 mm ice beads into porous microspheres, avoiding secondary breakage. Furthermore, this technology allows for the formation of a precursor through initial sintering at 450 ℃ for 10 h, significantly shorter than traditional methods. By using spray freeze-drying, the particles of the lithium supplement material are refined, effectively improving the material's cycle stability. This method can also be effectively extended to other types of lithium supplement materials.
[0015] Preferably, the atmosphere is one of argon, oxygen, and nitrogen. The first sintering temperature is 300-500℃, the second sintering temperature is 500-700℃, and the third sintering temperature is 750-900℃. This scheme uses argon protection throughout the process, with no hydrogen / ammonia reduction steps, making the process inherently safe. The waste liquid is only deionized water, meeting clean production requirements.
[0016] Preferably, the first sintering time is 5-20 hours, the second sintering time is 5-20 hours, and the third sintering time is 10-90 hours, but it is not limited to the listed values; other unlisted values within this range are also applicable. This solution achieves a secondary sphericity ≥0.92, forming point-to-surface contact with the cathode material, significantly improving the compaction density.
[0017] Secondly, the present invention provides a lithium-ion battery cathode lithium replenishing agent material, which is prepared by the lithium-ion battery cathode lithium replenishing agent preparation method.
[0018] Thirdly, the present invention provides a lithium-ion battery positive electrode sheet, comprising a current collector, a lithium-based positive electrode material disposed on the current collector, and the aforementioned lithium replenishing agent, wherein the lithium-based positive electrode material is selected from at least one of lithium titanate, lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, and lithium manganese oxide.
[0019] Fourthly, the present invention provides a lithium-ion battery comprising the aforementioned positive electrode sheet. The present invention effectively suppresses the generation of gaseous byproducts such as CO2 or inert solid deposits by the lithium replenishing agent during cycling due to side reactions, thereby significantly reducing the rate of increase in battery gas production and interfacial impedance, and avoiding performance degradation caused by these factors.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] This invention aims to provide a lithium-ion battery cathode lithium replenishment agent and its supporting preparation technology, cathode sheet, and corresponding battery system. Its core strategy involves reacting transition metal oxides with excess lithium source to directionally construct a lithium-rich phase, represented by Li5AlO4, which theoretically exhibits a significantly higher specific capacity than traditional materials such as Li2MoO3.
[0022] A three-stage gradient sintering process is employed to form a dense and uniform crystal network, effectively suppressing lattice oxygen escape and transition metal dissolution, and blocking side reaction gas generation pathways. While expanding reversible lithium supply, the initial irreversible lithium consumption is minimized through lattice anchoring, thereby synergistically improving battery energy density and long-term cycle stability. Through a combination of lithium-rich phase design, low-temperature gradient sintering, and ice bead template morphology control, this method significantly outperforms existing technologies in key indicators such as lithium replenishment capacity, cycle stability, and process feasibility, providing a safe, efficient, and low-cost lithium replenishment method for high-energy-density lithium-ion batteries. Attached Figure Description
[0023] Figure 1 SEM image of LAO, the target product prepared in Example 1;
[0024] Figure 2 SEM image of the target product LAO prepared in Example 2;
[0025] Figure 3 SEM image of the target product LAO prepared in Example 3;
[0026] Figure 4 SEM image of the target product LAO prepared in Example 4;
[0027] Figure 5 A flowchart for preparing the target product;
[0028] Figure 6 The charge-discharge cycle capacity curves of batteries in Examples 1-3 are shown below.
[0029] Figure 7 The graphs show the battery charge-discharge cycle capacity curves for Example 4 and existing technical solutions. Detailed Implementation
[0030] This invention provides a method for preparing a lithium-ion battery cathode lithium replenishing agent, such as... Figure 5 As shown, the steps are as follows:
[0031] (1) Batching and ball milling: Batching is carried out according to the set molar ratio of transition metal oxide (Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and lithium source (lithium carbonate, anhydrous lithium hydroxide or high-purity LiOH·H2O). Al2O3:LiOH·H2O=1:10 is preferred. The resulting mixture is wet ball milled in the presence of dispersant and dried to obtain material A.
[0032] (2) Spray quick-freeze-freeze-drying: After diluting material A with deionized water, it is spray quick-freeze to form ice beads with an average particle size of about 0.001-10 mm. Then, it is freeze-dried under vacuum of 0.03-300 Pa for 2 h to directly obtain porous microsphere powder, which significantly shortens the traditional 12 h drying cycle and eliminates the need for secondary crushing.
[0033] (3) Three-stage gradient sintering: The obtained powder is subjected to the following processes under argon protection: First sintering: 450 ℃ for 10–12 h, and after cooling, material B is obtained; Second sintering: Material B is ground and then held at 600 ℃ for 10–12 h, and after cooling, material C is obtained; Third sintering: Material C is finely ground and sieved, and then held at 800 ℃ for 65–70 h, finally obtaining a lithium-rich lithium supplement with a sphericity ≥0.92 and uniform particle size distribution.
[0034] This process uses inert argon gas throughout, eliminating the need for hydrogen / ammonia reduction, and the waste liquid is only deionized water, meeting clean production requirements. Low-temperature short-time pre-crystallization and gradient densification work together to reduce energy consumption by about 35%, and the resulting lithium replenishment agent forms ideal point-to-surface contact with the positive electrode active material, significantly improving compaction density and electrochemical performance.
[0035] Example 1:
[0036] (1) The preparation of the lithium supplement material with the chemical formula Li5AlO4 in this embodiment includes the following steps:
[0037] Take 0.997g Al2O3 and 4.023g LiOH·H2O, add 25g of ball milling beads and ethanol covering the beads, and perform wet ball milling for 2.5-3h; dry to obtain material A;
[0038] (2) Dissolve material A in 100ml of deionized water by stirring until there is no lumps or precipitates at the bottom, resulting in a turbid solution. Continue to add 100ml of deionized water while stirring and diluting until there is no obvious precipitate at the bottom of the container. Use a gas compressor to drive a sprayer to spray the diluted solution into liquid nitrogen for rapid freezing. The solution sprayed into liquid nitrogen is frozen into solid spherical ice beads with a particle size of about 0.5mm. Place the frozen solid ice beads in a stainless steel basin into a vacuum freeze dryer and freeze-dry the above frozen material under a pressure of about 0.03-300Pa. After drying, a milky white powder is obtained.
[0039] (3) The milky white powder obtained in step (2) is placed in a tube furnace and sintered at 450°C for 10 hours under an argon protective atmosphere. The powder is then cooled with the furnace to obtain the first sintered product B.
[0040] (4) Grind the primary sintering product B obtained in step (3) in a glove box, and after grinding, place it in a tube furnace and sinter at 550°C for 10 hours in an argon protective atmosphere. Cool with the furnace to obtain the secondary sintering product C.
[0041] (5) The secondary sintering product C obtained in step (4) is finely ground in a glove box, passed through a 200-mesh sieve, placed in a tube furnace, and sintered at 800°C for 60 hours under an argon protective atmosphere. The furnace is then cooled to obtain the final target product Li5AlO4.
[0042] pass Figure 1 It can be seen that the precursor material of Example 1 has a uniform morphology, a particle size of 10-18 nm, and uniform and dense surface grain growth.
[0043] Example 2:
[0044] (1) The preparation of the lithium supplement material with the chemical formula Li5AlO4 in this embodiment includes the following steps:
[0045] Take 0.997g Al2O3 and 4.224g LiOH·H2O, add 25g of ball milling beads and ethanol covering the beads, and perform wet ball milling for 2.5-3h; dry to obtain material A;
[0046] (2) Dissolve material A in 100ml of deionized water by stirring until there is no lumps or precipitates at the bottom, resulting in a turbid solution. Continue to add 100ml of deionized water while stirring and diluting until there is no obvious precipitate at the bottom of the container. Use a gas compressor to drive a sprayer to spray the diluted solution into liquid nitrogen for rapid freezing. The solution sprayed into liquid nitrogen is frozen into solid spherical ice beads with a particle size of about 0.5mm. Place the frozen solid ice beads in a stainless steel basin into a vacuum freeze dryer and freeze-dry the above frozen material under a pressure of about 0.03-300Pa. After drying, a milky white powder is obtained.
[0047] (3) The milky white powder obtained in step (2) is placed in a tube furnace and sintered at 450°C for 12 hours under an argon protective atmosphere. The powder is then cooled with the furnace to obtain the first sintered product B.
[0048] (4) Grind the primary sintering product B obtained in step (3) in a glove box, and after grinding, place it in a tube furnace and sinter at 600°C for 12 hours under an argon protective atmosphere. Cool with the furnace to obtain the secondary sintering product C.
[0049] (5) The secondary sintering product C obtained in step (4) is finely ground in a glove box, passed through a 200-mesh sieve, placed in a tube furnace, and sintered at 800°C for 70 hours under an argon protective atmosphere. The furnace is then cooled to obtain the final target product Li5AlO4.
[0050] pass Figure 2 It can be seen that the precursor material of the product in Example 2 has a relatively uniform morphology, with a particle size of 8-25 nm and relatively uniform surface grain growth.
[0051] Example 3:
[0052] (1) The preparation of the lithium supplement material with the chemical formula Li5AlO4 in this embodiment includes the following steps:
[0053] Take 0.997g Al2O3 and 4.023g LiOH·H2O, add 25g of ball milling beads and ethanol covering the beads, and perform wet ball milling for 2.5-3h; dry to obtain material A;
[0054] (2) Dissolve material A in 100ml of deionized water by stirring until there is no lumps or precipitates at the bottom, resulting in a turbid solution. Continue to add 100ml of deionized water while stirring and diluting until there is no obvious precipitate at the bottom of the container. Use a gas compressor to drive a sprayer to spray the diluted solution into liquid nitrogen for rapid freezing. The solution sprayed into liquid nitrogen is frozen into solid spherical ice beads with a particle size of about 0.5mm. Place the frozen solid ice beads in a stainless steel basin into a vacuum freeze dryer and freeze-dry the above frozen material under a pressure of about 0.03-300Pa. After drying, a milky white powder is obtained.
[0055] (3) The milky white powder obtained in step (2) is placed in a tube furnace and sintered at 480°C for 14 hours under an argon protective atmosphere. The powder is then cooled with the furnace to obtain the first sintered product B.
[0056] (4) Grind the primary sintering product B obtained in step (3) in a glove box, and after grinding, place it in a tube furnace and sinter at 600°C for 14 hours under an argon protective atmosphere. Cool with the furnace to obtain the secondary sintering product C.
[0057] (5) The secondary sintering product C obtained in step (4) is finely ground in a glove box, passed through a 200-mesh sieve, placed in a tube furnace, and sintered at 850°C for 70 hours under an argon protective atmosphere. The furnace is then cooled to obtain the final target product Li5AlO4.
[0058] pass Figure 3 It can be seen that the particle size of the product in Example 3 is 20-50 nm, which is larger and coarser than that in Example 1, and the uniformity is also poor.
[0059] Example 4:
[0060] (1) The preparation of the lithium supplement material with the chemical formula LiNiO2 in this embodiment includes the following steps:
[0061] Take 3.7345g Ni2O3 and 4.226g LiOH·H2O, add 30g of ball milling beads and ethanol covering the beads, and perform wet ball milling for 2.5-3h; dry to obtain material A;
[0062] (2) Dissolve material A in 100ml of deionized water by stirring until there is no lumps or precipitates at the bottom, resulting in a turbid solution. Continue to add 100ml of deionized water while stirring and diluting until there is no obvious precipitate at the bottom of the container. Use a gas compressor to drive a sprayer to spray the diluted solution into liquid nitrogen for rapid freezing. The solution sprayed into liquid nitrogen is frozen into solid spherical ice beads with a particle size of about 0.7mm. Place the frozen solid ice beads in a stainless steel basin into a vacuum freeze dryer and freeze-dry the frozen material under a pressure of about 30Pa. After drying, a milky white powder is obtained.
[0063] (3) The milky white powder obtained in step (2) is placed in a tube furnace and sintered at 450°C for 10 hours under an argon protective atmosphere. The powder is then cooled with the furnace to obtain the first sintered product B.
[0064] (4) Grind the primary sintering product B obtained in step (3) in a glove box, and after grinding, place it in a tube furnace and sinter at 550°C for 10 hours in an argon protective atmosphere. Cool with the furnace to obtain the secondary sintering product C.
[0065] (5) The secondary sintering product C obtained in step (4) is finely ground in a glove box, passed through a 200-mesh sieve, placed in a tube furnace, and sintered at 800°C for 60 hours under an argon protective atmosphere. The furnace is then cooled to obtain the final target product LiNiO2.
[0066] pass Figure 4 It can be seen that the particle size of the product in Example 4 is 10-20 nm, the precursor material has a uniform morphology, and the surface grains grow uniformly and densely, indicating that the method in this invention is also very applicable to the other raw materials mentioned.
[0067] pass Figure 6 As can be seen, compared with existing processes, Examples 1, 2, and 3 prepared using the method of this patent all have advantages in cycle stability. Example 2 has a higher initial capacity, presumably because the sintering time is shorter and the loss of Li is less. However, due to insufficient sintering time, the formed crystal is not thermodynamically stable enough, thus resulting in insufficient cycle stability. Furthermore, in Example 3, we increased the lithium ratio in the raw materials and reduced the sintering time to compensate for the loss of Li during the long sintering process. However, judging from the electrochemical data of Example 3, Example 1 still has better cycle stability.
[0068] pass Figure 7As can be seen, compared with existing processes, the preparation of Example 4 using the method of this patent has advantages in cycle stability. The initial capacity is low, which is presumably due to lithium loss during long-term sintering. However, the cycle stability is still better than existing processes, indicating that the lithium replenishing agents for other transition metal elements prepared by the method of this invention also have advantages.
[0069] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a lithium-ion battery cathode lithium replenishing agent material, characterized in that, include: The transition metal source and lithium source were mixed according to the molar ratio, a dispersant was added, and the mixture was wet ball milled and dried to obtain material A. Material A is diluted and dissolved with deionized water, then spray-frozen to solidify into ice beads and freeze-dried to obtain powder. The powder is then sintered for the first time in an atmosphere and cooled to obtain material B. Material B is ground, then sintered a second time in an atmosphere, and cooled to obtain material C; The material C is finely ground, sieved, and then sintered a third time in an atmosphere to obtain the lithium supplement Li. x B y O z .
2. The method for preparing a lithium-ion battery cathode lithium replenishing agent material according to claim 1, characterized in that, The transition metal source is one or more of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn oxides, and the lithium source is one or more of lithium carbonate, anhydrous lithium hydroxide, and high-purity LiOH·H2O.
3. The method for preparing a lithium-ion battery cathode lithium replenishing agent material according to claim 2, characterized in that, The molar ratio of the transition metal source and the lithium source MO and Li is 1:6 to 1:
10.
4. The method for preparing a lithium-ion battery cathode lithium replenishing agent material according to claim 1, characterized in that, The ice beads have a particle size of 0.001-10 mm, and the freeze-drying pressure is 0.03-300 Pa.
5. The method for preparing a lithium-ion battery cathode lithium replenishing agent material according to claim 1, characterized in that, The atmosphere is one of argon, oxygen, and nitrogen. The first sintering temperature is 300-500℃, the second sintering temperature is 500-700℃, and the third sintering temperature is 750-900℃.
6. The method for preparing a lithium-ion battery cathode lithium replenishing agent material according to claim 1, characterized in that, The first sintering time is 5-20 hours, the second sintering time is 5-20 hours, and the third sintering time is 10-90 hours.
7. A lithium-ion battery positive electrode lithium replenishing agent material, characterized in that, The lithium supplement material is prepared by the preparation method according to any one of claims 1-6.
8. A positive electrode sheet for a lithium-ion battery, characterized in that, It includes a current collector, a lithium-based cathode material disposed on the current collector, and a lithium replenishing agent as described in claim 7.
9. The positive electrode sheet according to claim 8, characterized in that, The lithium-based cathode material is selected from at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, and lithium manganese oxide.
10. A lithium-ion battery, characterized in that, The lithium-ion battery comprises the positive electrode sheet as described in claim 8 or 9.