Negative plate of high-energy sodium ion battery and sodium ion battery
By combining a phosphorus-based composite anode with hard carbon in sodium-ion batteries, along with single-walled carbon nanotubes and conductive carbon black, and using PAANa as a binder, the problems of low energy density and poor cycle performance of sodium-ion batteries were solved, achieving high energy density and stable battery performance.
Patent Information
- Application Number
- CN202511062712.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-10-31
AI Technical Summary
Sodium-ion batteries have a low energy density, mainly due to the large atomic mass of Na, low specific capacity of the positive electrode, and disadvantageous voltage plateau. This limits the range of anode materials to be selected and also results in low specific capacity, leading to poor cycle performance.
A phosphorus-based composite anode material is combined with hard carbon, using single-walled carbon nanotubes and conductive carbon black as conductive agents, and PAANa as a binder. Through specific proportions of slurry formulation and preparation process, the viscosity and solid content of the slurry are optimized to construct a high-porosity electrode to buffer volume expansion and improve conductivity.
It improves the sodium storage capacity of the negative electrode and the energy density of the battery, enhances the cycle stability and conductivity of the battery, solves the dispersion and expansion problems of phosphorus-based composite negative electrodes, and improves the overall performance of the battery.
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Figure CN120878752A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, specifically to a high-energy sodium-ion battery negative electrode and a sodium-ion battery. Background Technology
[0002] Against the backdrop of profound changes in the global energy landscape and accelerated energy transition, sodium-ion batteries, as an emerging technology, have garnered widespread attention worldwide due to their unique advantages. Sodium-ion batteries have become a research hotspot in recent years due to their abundant raw material sources, low cost, and environmental friendliness, providing another option for the battery market.
[0003] Hard carbon, as a negative electrode material for sodium-ion batteries, has advantages such as being renewable, abundant in sources, inexpensive, and environmentally friendly, making it the most commercially mature negative electrode material currently available.
[0004] However, compared to the high energy density silicon-carbon anode in lithium batteries, hard carbon materials have a lower specific capacity, which limits the energy density of sodium-ion batteries. Although new anode materials such as Sn and Sb sodium storage metal alloy anodes have a higher specific capacity, they still cannot avoid the problem of excessively rapid cycle decay.
[0005] The underlying reasons for the low energy density of sodium-ion batteries are as follows:
[0006] For example, Na has a large atomic mass. The atomic mass of Na (23 g / mol) > that of Li (6.9 g / mol), and the mass increases by 3.3 times under the same charge transfer.
[0007] For example, the specific capacity of the positive electrode is relatively low, and the voltage plateau is inferior. (As shown in Table 1) The operating voltage of the positive electrode material in sodium-ion batteries is relatively low, and the voltage plateau matching degree with that of the negative electrode material is not as good as that of lithium-ion batteries. This makes the overall voltage window of the battery narrower, limiting the improvement of energy density.
[0008] The limitations of anode materials and their low specific capacity are significant drawbacks. The radius of Na⁺ (1.02 Å) is greater than that of Li⁺ (0.76 Å), and the interlayer spacing of graphite is insufficient for Na⁺ insertion and extraction, thus restricting the selection of anode materials for sodium-ion batteries. Hard carbon is currently the most commercially viable and promising anode material for sodium-ion batteries, but its specific capacity generally does not exceed 330 mAh / g, far lower than the theoretical specific capacity of graphite anodes (372 mAh / g). Meanwhile, while alloy and conversion-type anode materials have high theoretical specific capacities, they suffer from severe volume expansion problems. For example, tin-based alloys can expand by more than 300% during sodium storage, leading to electrode material pulverization, a sharp decline in cycle performance, and affecting the overall performance and lifespan of the battery, thus limiting their application in improving energy density. Summary of the Invention
[0009] The purpose of this invention is to provide a high-energy sodium-ion battery negative electrode and a sodium-ion battery, which have the characteristics of high sodium storage capacity of the negative electrode, high energy density of the battery and good cycle stability.
[0010] This invention can be achieved through the following technical solutions:
[0011] This invention relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. The negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of the components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.8. In this invention, the purpose of the slurry formulation is as follows: 1. To fully consider the volume expansion of the phosphorus-based composite anode during cycling, which leads to cycling degradation, a main material ratio of 1:9 or 2:8 is preferred to maintain good cycling performance; 2. Since the phosphorus-based composite anode has poor conductivity, a high-solids slurry preferably contains 0.05%-0.1% single-walled carbon nanotubes to improve the electrode conductivity; 3. Based on the differences in the performance of the main materials, 1%-1.5% CMC and 0.5%-0.8% PAANa are selected as dispersants for hard carbon and phosphorus-based composite anodes, respectively.
[0012] Furthermore, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0013] Furthermore, PAANa is sodium polyacrylate. PAANa can achieve strong nanoscale dispersion through ultra-high density carboxyl groups, and effectively solves the dispersion and expansion problems of phosphorus-based composite anodes by buffering volume stress with flexible chains and dynamic hydrogen bond networks.
[0014] Furthermore, the preparation method of this negative electrode includes the following steps:
[0015] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0016] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0017] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0018] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution.
[0019] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to the PAANa adhesive obtained in S4 in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry.
[0020] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry;
[0021] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR and vacuum slowly stir (10-15HZ revolution, 10-15HZ rotation, stirring for 25-35min). After sieving, proceed with the coating process to obtain the negative electrode sheet.
[0022] Furthermore, in the mixed slurry, the mass ratio of phosphorus-based composite anode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.8. The purpose of this slurry formulation is: 1. To fully consider the volume expansion of the phosphorus-based composite anode during cycling, which leads to cycling degradation, a main material ratio of 1:9 or 2:8 is preferred to maintain good cycling performance; 2. Due to the poor conductivity of the phosphorus-based composite anode, a high-solids slurry preferably includes 0.05%-0.1% single-walled carbon nanotubes to improve electrode conductivity; 3. Based on the differences in the performance of the main materials, 1%-1.5% CMC and 0.5%-0.8% PAANa are selected as dispersants for the hard carbon and phosphorus-based composite anodes, respectively.
[0023] Furthermore, in step S7, the discharge viscosity is 2000-4000 CP and the slurry solid content is 54-55%.
[0024] This viscosity range can suppress sedimentation and optimize rheological properties, simultaneously achieving good slurry uniformity, excellent leveling, and long cycle life. If the viscosity is too high, the overall dispersion uniformity of the slurry will be poor, the hard carbon and phosphorus-based composite negative electrode slurry will not be fully mixed, the active material contained in the electrode will have poor consistency, and the battery cycle life will be poor. If the viscosity is too low, the leveling of the current collector during slurry coating will be poor, the surface density of the electrode will be uneven, and there will be a risk of sodium precipitation in the later stage.
[0025] Furthermore, the mass content of the dispersion solution is 1.8%-2.5%; the mass content of the PAANa solution is 2%-3.5%.
[0026] Further, in step S3, the solid content of the hard carbon slurry is 52-54%, and the viscosity is 1500-2500 CP. Further, in step S5, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000 CP. Another aspect of the present invention is to protect a sodium-ion battery obtained by winding or laminating the above-described negative electrode sheet.
[0027] This invention provides a high-energy sodium-ion battery negative electrode and a sodium-ion battery, which have the following beneficial effects:
[0028] First, the negative electrode has a high sodium storage capacity. The negative electrode of this invention uses a phosphorus-based composite negative electrode and hard carbon as the main active material in its slurry composition. The theoretical capacity of the phosphorus-based material is more than eight times that of hard carbon. Phosphorus stores sodium through a multi-step alloying reaction: P + xNa + +xe − →NaxP (x≤3, final product Na3P), meaning each phosphorus atom can combine with 3 sodium atoms (Na3P), increasing the sodium storage capacity of the negative electrode.
[0029] Secondly, the battery has high energy density. This invention fully leverages the advantage of phosphorus-based composite anodes having a higher specific capacity than hard carbon anodes. When assembling the same cathode sheet, it can reduce the surface density of the anode coating, thereby increasing the energy density of sodium-ion batteries (e.g., ...). Figure 1 (as shown)
[0030] Third, it exhibits good cycle stability and conductivity. During the homogenization process with phosphorus-based composite materials, PAANa, acting as a dispersant, can construct a high-porosity electrode, providing a buffer space for phosphorus expansion. Simultaneously, the polymer chains of PAANa allow Na+ to absorb the volume stress of phosphorus particles through viscoelastic deformation during the insertion / extraction process, suppressing electrode volume expansion and improving battery cycle life. Adding single-walled carbon nanotubes to the slurry improves the conductivity of the phosphorus-based composite material. Single-walled carbon nanotubes have a stable structure, and the connections between internal carbon atoms are very flexible. When external force is applied, the carbon atom faces bend and deform, allowing the carbon atoms to maintain structural stability without rearranging to adapt to the force. This effectively alleviates the volume effect of phosphorus-based composite materials during charge and discharge, maintaining a good structure and conductive network. (e.g.) Figure 2 (As shown). Attached Figure Description
[0031] Figure 1 A comparison of the gravimetric energy density of sodium-ion batteries made with high-energy negative electrode + polyanion positive electrode and sodium-ion batteries made with hard carbon negative electrode + polyanion positive electrode.
[0032] Figure 2 Comparison of cycle stability of high-energy sodium-ion batteries with and without PAANa during long-term cycling. Detailed Implementation
[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to embodiments.
[0034] This invention relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. The negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of the components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.8.
[0035] Furthermore, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0036] Furthermore, PAANa is sodium polyacrylate. PAANa can achieve strong nanoscale dispersion through ultra-high density carboxyl groups, and effectively solves the dispersion and expansion problems of phosphorus-based composite anodes by buffering volume stress with flexible chains and dynamic hydrogen bond networks.
[0037] Furthermore, the preparation method of this negative electrode includes the following steps:
[0038] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0039] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0040] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0041] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution.
[0042] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to the PAANa adhesive obtained in S4 in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry.
[0043] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry;
[0044] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR and vacuum slowly stir (10-15Hz revolution, 10-15Hz rotation, stirring for 25-35 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet.
[0045] Furthermore, in the mixed slurry, the mass ratio of phosphorus-based composite anode: hard carbon: single-walled carbon nanotube: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.8.
[0046] Furthermore, in step S7, the discharge viscosity is 2000-4000 CP and the slurry solid content is 54-55%.
[0047] Furthermore, the mass content of the dispersion solution is 1.8-2.5%; the mass content of the PAANa solution is 2-3.5%.
[0048] Further, in step S3, the solid content of the hard carbon slurry is 52-54%, and the viscosity is 1500-2500 CP. Further, in step S5, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000 CP. Example 1
[0049] This embodiment relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. Its characteristics are: the negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 19.2:82:0.05:1:1.25:0.82:0.8. Specifically, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0050] In this embodiment, the method for preparing the negative electrode includes the following steps:
[0051] S1. Preparation of dispersion solution: CMC is added to pure water and stirred to obtain dispersion solution; specifically, the mass content of dispersion solution is 2.5%.
[0052] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0053] S3. Preparation of hard carbon slurry: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon slurry; specifically, the solid content of hard carbon slurry is 52-54% and the viscosity is 1500-2500CP.
[0054] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in the pure water to obtain PAANa adhesive solution; specifically, the mass content of PAANa adhesive solution is 3.5%.
[0055] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added in batches to the PAANa adhesive obtained in S4, and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry; specifically, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000CP.
[0056] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir. Add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry.
[0057] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry with pure water, add SBR and perform vacuum slow stirring (15Hz revolution, 13Hz rotation, stirring for 25 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet. Specifically, the output viscosity is 2000-4000 CP, and the slurry solid content is 54-55%.
[0058] Example 2
[0059] This embodiment relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. Its characteristics are: the negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 14.2:76.7:0.1:0.75:1:1.2:0.65. Specifically, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0060] In this embodiment, the method for preparing the negative electrode includes the following steps:
[0061] S1. Preparation of dispersion solution: CMC is added to pure water and stirred to obtain dispersion solution; specifically, the mass content of dispersion solution is 2.1%.
[0062] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0063] S3. Preparation of hard carbon slurry: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon slurry; specifically, the solid content of hard carbon slurry is 52-54% and the viscosity is 1500-2500CP.
[0064] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution; specifically, the mass content of PAANa adhesive solution is 2.7%.
[0065] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added in batches to the PAANa adhesive obtained in S4, and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry; specifically, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000CP.
[0066] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir. Add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry.
[0067] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry with pure water, add SBR and perform vacuum slow stirring (13Hz revolution, 10Hz rotation, stirring for 35 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet. Specifically, the output viscosity is 2000-4000 CP, and the slurry solid content is 54-55%.
[0068] Example 3
[0069] This embodiment relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. Its characteristics are: the negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 9.6: 86.3: 0.075: 0.5: 1.5: 1.0: 0.5. Specifically, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0070] In this embodiment, the method for preparing the negative electrode includes the following steps:
[0071] S1. Preparation of dispersion solution: CMC is added to pure water and stirred to obtain dispersion solution; specifically, the mass content of dispersion solution is 1.8%.
[0072] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0073] S3. Preparation of hard carbon slurry: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon slurry; specifically, the solid content of hard carbon slurry is 52-54% and the viscosity is 1500-2500CP.
[0074] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution; specifically, the mass content of PAANa adhesive solution is 2%.
[0075] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added in batches to the PAANa adhesive obtained in S4, and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry; specifically, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000CP.
[0076] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir. Add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry.
[0077] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry with pure water, add SBR and perform vacuum slow stirring (10Hz revolution, 15Hz rotation, stirring for 30 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet. Specifically, the output viscosity is 2000-4000 CP, and the slurry solid content is 54-55%.
[0078] Example 4
[0079] This embodiment relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. Its characteristics are: the negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 12.2:84.1:0.08:0.6:1.2:0.9:0.7. Specifically, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0080] In this embodiment, the method for preparing the negative electrode includes the following steps:
[0081] S1. Preparation of dispersion solution: CMC is added to pure water and stirred to obtain dispersion solution; specifically, the mass content of dispersion solution is 1.9%.
[0082] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0083] S3. Preparation of hard carbon slurry: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon slurry; specifically, the solid content of hard carbon slurry is 52-54% and the viscosity is 1500-2500CP.
[0084] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution; specifically, the mass content of PAANa adhesive solution is 3.2%.
[0085] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added in batches to the PAANa adhesive obtained in S4, and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry; specifically, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000CP.
[0086] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir. Add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry.
[0087] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry with pure water, add SBR and perform vacuum slow stirring (14Hz revolution, 13Hz rotation, stirring for 29 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet. Specifically, the output viscosity is 2000-4000 CP, and the slurry solid content is 54-55%.
[0088] Example 5
[0089] This embodiment relates to a high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder. Its characteristics are: the negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 16.2:78.6:0.08:0.7:1.1:0.9:0.7. Specifically, this phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
[0090] In this embodiment, the method for preparing the negative electrode includes the following steps:
[0091] S1. Preparation of dispersion solution: CMC is added to pure water and stirred to obtain dispersion solution; specifically, the mass content of dispersion solution is 2.2%.
[0092] S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution.
[0093] S3. Preparation of hard carbon slurry: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon slurry; specifically, the solid content of hard carbon slurry is 52-54% and the viscosity is 1500-2500CP.
[0094] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution; specifically, the mass content of PAANa adhesive solution is 2.5%.
[0095] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added in batches to the PAANa adhesive obtained in S4, and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry; specifically, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000CP.
[0096] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir. Add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry.
[0097] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry with pure water, add SBR and perform vacuum slow stirring (14Hz revolution, 11Hz rotation, stirring for 32 minutes). After sieving, proceed with the coating process to obtain the negative electrode sheet. Specifically, the output viscosity is 2000-4000 CP, and the slurry solid content is 54-55%.
[0098] Application Example 1
[0099] This embodiment relates to a high-energy-density sodium-ion battery negative electrode sheet, wherein the mass ratio of different components of the negative electrode sheet is: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa = 19.2: 76.7: 0.1: 1: 1.2: 1: 0.8.
[0100] The preparation steps of this negative electrode include:
[0101] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0102] S2. Preparation of conductive adhesive solution: Add conductive carbon black to S1 adhesive solution and stir to completely disperse the conductive carbon black in the adhesive solution to obtain conductive adhesive solution.
[0103] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0104] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution.
[0105] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to S4 PAANa adhesive in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry.
[0106] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion.
[0107] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR, vacuum and slowly stir for 30 minutes. The output viscosity is 2000CP-4000CP and the solid content of the slurry is 54%-55%. After sieving and coating, perform post-processing.
[0108] The negative electrode sheet prepared by the above coating is assembled with a polyanion positive electrode sheet, a separator, an electrolyte, etc. to form a sodium-ion battery.
[0109] Application Example 2
[0110] This embodiment relates to a high-energy-density sodium-ion battery negative electrode sheet, the mass ratio of different components of the negative electrode sheet is: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa = 9.6: 86.3: 0.1: 1: 1.4: 1: 0.6.
[0111] The preparation steps of this negative electrode include:
[0112] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0113] S2. Preparation of conductive adhesive solution: Add conductive carbon black to S1 adhesive solution and stir to completely disperse the conductive carbon black in the adhesive solution to obtain conductive adhesive solution.
[0114] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0115] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution.
[0116] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to S4 PAANa adhesive in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry.
[0117] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion.
[0118] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR, vacuum and slowly stir for 30 minutes. The output viscosity is 2000CP-4000CP and the solid content of the slurry is 54%-55%. Sieve the material, coat it and perform post-processing.
[0119] The negative electrode sheet prepared by the above coating is assembled with a polyanion positive electrode sheet, a separator, an electrolyte, etc. to form a sodium-ion battery.
[0120] Application Example 3
[0121] This embodiment relates to a high-energy-density sodium-ion battery anode sheet, the mass ratio of different components of the anode sheet is: phosphorus-based composite anode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa=14.4:81.5:0.08:1.22:1.2:0.8:0.8.
[0122] The preparation method of this negative electrode includes the following steps:
[0123] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0124] S2. Preparation of conductive alkaline solution: Add conductive carbon black to S1 adhesive solution and stir to completely disperse the conductive carbon black in the adhesive solution to obtain conductive adhesive solution.
[0125] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0126] S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution.
[0127] S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to S4 PAANa adhesive in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry.
[0128] S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion.
[0129] S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR, vacuum and slowly stir for 30 minutes. The output viscosity is 2000CP-4000CP and the solid content of the slurry is 54%-55%. Sieve the material, coat it, and then perform post-processing.
[0130] The negative electrode sheet prepared by the above coating is assembled with a polyanion positive electrode sheet, a separator, an electrolyte, etc. to form a sodium-ion battery.
[0131] Comparative Example 1
[0132] This embodiment relates to a sodium-ion battery negative electrode sheet, wherein the mass ratio of different components of the negative electrode sheet is: hard carbon: conductive carbon black: CMC: SBR = 94: 1.5: 2: 2.5.
[0133] The preparation method of this negative electrode includes the following steps:
[0134] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0135] S2. Preparation of conductive adhesive solution: Add conductive carbon black to S1 adhesive solution and stir to completely disperse the conductive carbon black in the adhesive solution to obtain conductive adhesive solution.
[0136] S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste.
[0137] S4. Post-processing: After adjusting the viscosity of S3 slurry by adding pure water, add SBR, vacuum and slowly stir for 30 minutes. The output viscosity is 2000CP-4000CP and the solid content of the slurry is 54%-55%. Sieve the material, coat it, and then perform post-processing.
[0138] The negative electrode sheet prepared after the above coating is assembled with a polyanion positive electrode sheet, a separator, an electrolyte, etc., to form a sodium-ion battery. The main difference between Comparative Example 1 and Application Example 1 is that no phosphorus-based composite material is added.
[0139] Comparative Example 2
[0140] This embodiment relates to a sodium-ion battery negative electrode sheet, wherein the mass ratio of different components of the negative electrode sheet is: phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR = 19.2: 76.7: 0.1: 1: 2: 1.
[0141] The preparation method of this negative electrode includes the following steps:
[0142] S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution;
[0143] S2. Preparation of conductive adhesive solution: Add conductive carbon black to S1 adhesive solution and stir to completely disperse the conductive carbon black in the adhesive solution to obtain conductive adhesive solution.
[0144] S3. Preparation of slurry: After mixing the hard carbon + phosphorus-based composite negative electrode, add it to the S2 conductive adhesive in batches and stir to disperse it completely to obtain the slurry.
[0145] S4. Dispersion treatment: Add S3 slurry to single-walled carbon nanotubes for high-speed dispersion;
[0146] S5. Post-processing: Add pure water to S4 slurry to adjust viscosity, then add SBR, vacuum and slowly stir for 30 minutes. The output viscosity is 2000CP-4000CP and the slurry solid content is 54%-55%. Sieve and coat.
[0147] The negative electrode sheet prepared after the above coating is assembled with a polyanion positive electrode sheet, a separator, an electrolyte, etc., to form a sodium-ion battery. The main difference between Comparative Example 2 and Application Example 1 is that PAANa was not used to disperse the phosphorus-based composite negative electrode, and PAANa was not present in the slurry.
[0148] The negative electrode, polyanion-type positive electrode, separator, and electrolyte stack prepared in Application Examples 1-3 and Comparative Examples 1-2 were used to fabricate a 1Ah soft-pack sodium-ion battery for testing. The test results are shown below:
[0149]
[0150] The test results show that:
[0151] In Application Example 1, the active material is a phosphorus-based composite anode: hard carbon in a ratio of 2:8. In Comparative Example 1, the active material is hard carbon. The anode coating density in Application Example 1 is only 1 / 3 of that in Comparative Example 1, and the gravimetric energy density is increased by 36.5% compared to Comparative Example 1 (e.g., ...). Figure 1 The high specific capacity of the phosphorus-based composite anode in slurry fusion allows for a reduction in anode coating density, thus reducing battery weight and increasing the energy density of sodium-ion batteries when manufacturing batteries of the same capacity.
[0152] The phosphorus-based composite anode + PAANa slurry in Example 1 and the phosphorus-based composite anode + CMC slurry (without PAANa in the slurry) in Comparative Example 2 showed that the capacity retention rates of Example 1 and Comparative Example 2 after 200 cycles at 1C were 95.15% and 91.77%, respectively (e.g., ...). Figure 2 PAANa can construct high-porosity electrodes, and its flexible chains and dynamic hydrogen bond network buffer volume stress, effectively solving the problem of expansion of phosphorus-based composite anodes. During cycling, the polymer chains of PAANa enable Na+ to absorb the volume stress of phosphorus particles through viscoelastic deformation during the insertion and extraction process, effectively suppressing battery volume expansion and ensuring long-term battery cycling.
[0153] The above embodiments are merely specific examples of the present invention, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.
Claims
1. A high-energy sodium-ion battery negative electrode sheet, comprising a negative electrode active material, a conductive agent, and a binder, characterized in that: The negative electrode active material is a phosphorus-based composite negative electrode and hard carbon; the conductive agent is single-walled carbon nanotubes and conductive carbon black; the binder is CMC, SBR, and PAANa; the mass ratio of several components is as follows: the mass ratio of phosphorus-based composite negative electrode: hard carbon: single-walled carbon nanotubes: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.
8.
2. The high-energy sodium-ion battery negative electrode sheet according to claim 1, characterized in that: The phosphorus-based composite negative electrode is a red phosphorus porous carbon composite material.
3. The high-energy sodium-ion battery negative electrode sheet according to claim 1, characterized in that: The preparation method of this negative electrode includes the following steps: S1. Preparation of dispersion solution: Add CMC to pure water and stir to obtain dispersion solution; S2. Preparation of conductive adhesive solution: Add conductive carbon black to the dispersion solution obtained in S1, stir to completely disperse the conductive carbon black in the solution, and obtain conductive adhesive solution. S3. Preparation of hard carbon paste: Add hard carbon to S2 conductive adhesive in batches and stir to completely disperse the hard carbon to obtain hard carbon paste. S4. Preparation of PAANa adhesive solution: PAANa is added to pure water in batches and stirred until PAANa is completely dissolved in pure water to obtain PAANa adhesive solution. S5. Preparation of phosphorus-based slurry: The phosphorus-based composite material is added to the PAANa adhesive obtained in S4 in batches and stirred thoroughly to disperse it completely, thus obtaining the phosphorus-based slurry. S6. Preparation of mixed slurry: Mix S3 hard carbon slurry and S5 phosphorus-based slurry and stir, then add single-walled carbon nanotubes for high-speed dispersion to obtain mixed slurry; S7. Post-processing: After adjusting the viscosity of the S6 mixed slurry by adding pure water, add SBR, vacuum and slowly stir, sieve and discharge the material, and then perform coating and subsequent processing to obtain the negative electrode sheet.
4. The high-energy sodium-ion battery negative electrode sheet according to claim 3, characterized in that: In the mixed slurry, the mass ratio of phosphorus-based composite anode: hard carbon: single-walled carbon nanotube: conductive carbon black: CMC: SBR: PAANa is 9.6-19.2: 76.7-86.3: 0.05-0.1: 0.5-1: 1-1.5: 0.8-1.2: 0.5-0.
8.
5. The high-energy sodium-ion battery negative electrode sheet according to claim 3, characterized in that: In step S7, the discharge viscosity is 2000-4000 CP and the slurry solid content is 54-55%.
6. The high-energy sodium-ion battery negative electrode sheet according to claim 3, characterized in that: The mass content of the dispersion solution is 1.8-2.5%; the mass content of the PAANa solution is 2-3.5%.
7. The high-energy sodium-ion battery negative electrode sheet according to claim 3, characterized in that: In step S3, the solid content of the hard carbon slurry is 52-54%, and the viscosity is 1500-2500 CP.
8. The high-energy sodium-ion battery negative electrode sheet according to claim 7, characterized in that: In step S5, the solid content of the phosphorus-based slurry is 53-54%, and the viscosity is 3000-4000 CP.
9. A sodium-ion battery, characterized in that: Obtained by winding or stacking the negative electrode sheet according to any one of claims 1-8.