All-solid-state composite positive electrode sheet and preparation method and application thereof
By introducing terpenoid compounds as additives into all-solid-state batteries, the adhesion effect of components inside the positive electrode sheet is enhanced, solving the problem of interface contact deterioration caused by volume shrinkage and expansion, and significantly improving the cycle performance and capacity retention of the battery.
Patent Information
- Application Number
- CN202411961540.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2026-05-15
- Estimated Expiration
- 2044-12-30
AI Technical Summary
During cycling, the positive electrode active material of all-solid-state batteries shrinks and expands in volume due to the intercalation and deintercalation of lithium ions, which deteriorates the interfacial contact and leads to a decrease in battery performance. In the dry process, the binder polytetrafluoroethylene cannot provide sufficient interfacial adhesion, which affects the battery's cycle performance.
Terpenoids (such as camphene) are used as additives, mixed with positive electrode active material, solid electrolyte and conductive agent at high temperature, and PTFE binder is added at low temperature. The adhesion effect of the internal components of the electrode is enhanced by fibrosis treatment to prepare an all-solid composite positive electrode.
It significantly improves the long-cycle capacity retention of all-solid-state batteries, especially under low external pressure and room temperature conditions, enhances the close contact of components inside the electrode, and improves the overall performance of the battery.
Smart Images
Figure CN119725368B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery technology, specifically relating to an all-solid-state composite positive electrode sheet, its preparation method, and its application. Background Technology
[0002] In the field of new energy vehicles, the application of lithium-ion power batteries is becoming increasingly widespread, but the driving range has become a key bottleneck restricting its development. Improving the energy density of lithium-ion batteries is an effective strategy to alleviate range anxiety. All-solid-state lithium batteries, as one of the potential ultimate forms of commercial lithium batteries, replace flammable liquid electrolytes with solid electrolytes, offering not only a safer power battery solution but also higher energy density and better cycle performance. In all-solid-state batteries, the solid-solid interface contact inside the positive electrode is a key factor determining the battery's reversible capacity and capacity retention rate; therefore, optimizing these solid-solid interfaces is crucial for improving the performance of all-solid-state batteries.
[0003] Typically, composite cathode sheets consist of a positive electrode active material, a solid electrolyte, a conductive agent, and a polymer binder. The material formulation of composite cathode sheets has a significant impact on the performance of all-solid-state batteries, with the adhesive properties of the binder playing a decisive role in maintaining good contact between the various solid components and the tightness of the solid-solid interface. Currently, the manufacturing processes for cathode sheets are mainly divided into two types: wet processes and dry processes. Dry processes eliminate the need for solvents during production, thus avoiding complex drying and solvent recovery steps. This not only effectively reduces production costs and environmental pollution but also facilitates precise control of the electrode thickness.
[0004] However, current all-solid-state batteries still face the following challenges:
[0005] 1. During the cycling process of all-solid-state batteries, the volume shrinkage and expansion of the positive electrode active material due to lithium ion insertion / extraction may deteriorate the interfacial contact, leading to a decrease in battery performance. To ensure performance, high external pressures exceeding 50 MPa are typically required, which is inconsistent with the actual needs of commercializing all-solid-state batteries.
[0006] 2. The binder polytetrafluoroethylene (PTFE) commonly used in dry process has defects. PTFE cannot provide sufficient interfacial adhesion between the positive electrode active material, solid electrolyte, and conductive agent. Therefore, it cannot effectively guarantee solid-solid contact between the positive electrode active material, solid electrolyte, and conductive agent, resulting in poor cycle performance of all-solid-state batteries.
[0007] In view of the above problems, the present invention aims to provide a composite positive electrode that significantly improves the cycle performance of all-solid-state batteries to address these issues. Summary of the Invention
[0008] The purpose of this invention is to address at least one of the aforementioned problems by providing an all-solid-state composite positive electrode sheet, its preparation method, and its application. This addresses the issues in existing all-solid-state batteries where volume shrinkage and expansion of the positive electrode active material due to lithium-ion insertion / extraction can worsen interfacial contact, leading to decreased battery performance; and the problem that polytetrafluoroethylene (PTFE) binder in dry processes cannot provide sufficient interfacial adhesion between the positive electrode active material, solid electrolyte, and conductive agent. This solution effectively enhances the interfacial contact between the components within the electrode sheet, significantly reducing the loss of solid-solid contact during battery cycling, thereby enabling all-solid-state batteries to achieve excellent long-cycle capacity retention.
[0009] The objective of this invention is achieved through the following technical solution:
[0010] The first aspect of this invention discloses a method for preparing an all-solid-state composite positive electrode, comprising the following steps:
[0011] S1: Mix the positive electrode active material, solid electrolyte and conductive agent to obtain the first mixture;
[0012] S2: Under high temperature conditions, the additive terpenoid compound is mixed with the first mixture to obtain the second mixture;
[0013] S3: Under low temperature conditions, the adhesive is mixed with the second mixture to obtain the third mixture;
[0014] S4: The third mixture is fiberized and shaped to obtain the composite positive electrode sheet.
[0015] Preferably, in step S1, the positive electrode active material includes lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based oxide, sulfur, selenium, sulfides, selenides, and halides; the mass fraction of the positive electrode active material in the first mixture is 68-78%.
[0016] Preferably, in step S1, the solid electrolyte includes an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte; the mass fraction of the solid electrolyte in the first mixture is 19-29%.
[0017] Preferably, in step S1, the conductive agent includes carbon black, conductive graphite, carbon fiber, carbon nanofiber, carbon nanotube, and graphene; the mass fraction of the conductive agent in the first mixture is 3%.
[0018] Preferably, in step S2, the additive terpenoid compounds include monoterpenoid compounds, sesquiterpenoid compounds, and diterpenoid compounds; the mass fraction of the additive terpenoid compounds in the second mixture is 3-8%.
[0019] More preferably, in step S2, the additive terpene compound is camphene.
[0020] Preferably, in step S3, the adhesive comprises PTFE; the mass fraction of the adhesive in the third mixture is 0.5% to 2%.
[0021] Preferably, in step S2, the high temperature condition is the temperature condition that makes the additive liquid (melt); in step S3, the low temperature condition is the temperature condition that makes the additive solid.
[0022] More preferably, in step S2, the high temperature condition is 60-80°C; and in step S3, the low temperature condition is 10-30°C.
[0023] Preferably, in step S4, the fiberization involves applying shear force to the third mixture, and the molding includes hot rolling.
[0024] More preferably, in step S4, the fiberization includes ball milling, mechanical stirring, air jet milling and grinding, and the forming includes multi-stage hot rolling.
[0025] The second aspect of this invention discloses an all-solid-state composite positive electrode sheet, which is obtained by any of the preparation methods described above.
[0026] The third aspect of this invention discloses the application of the all-solid-state composite positive electrode sheet as described above in an all-solid-state battery.
[0027] Preferably, in the all-solid-state battery, the negative electrode sheet used can be a lithium indium alloy negative electrode sheet or a lithium titanate composite negative electrode sheet; it can also be a silicon material, graphite material, hard carbon material, soft carbon material, doped carbon material, composite material composed of silicon and graphite, hard carbon, soft carbon or doped carbon, tin-based material or alloy negative electrode composed of indium, lithium, aluminum and at least two of the above metals.
[0028] Preferably, the all-solid-state battery includes all-solid-state lithium batteries and all-solid-state sodium batteries.
[0029] Compared with the prior art, the present invention has the following beneficial effects:
[0030] The composite positive electrode provided by this invention significantly enhances the adhesion between the components within the electrode by utilizing terpenoid compounds as additives. This enhanced adhesion ensures that the components remain in close contact even after long-term cycling, effectively strengthening the interfacial contact between the components within the electrode and significantly reducing the loss of solid-solid contact within the positive electrode. This results in excellent long-cycle capacity retention for the all-solid-state battery. Consequently, the capacity retention of the positive electrode is significantly improved. The performance enhancement effect brought about by the introduction of terpenoid compounds is particularly evident under conditions of room temperature and low external pressure, further enhancing the overall performance of practical all-solid-state batteries. Attached Figure Description
[0031] Figure 1 This is a schematic flowchart of the composite positive electrode preparation process of the present invention;
[0032] Figure 2 This is an external photograph of the self-supporting all-solid-state composite positive electrode sheet prepared in Example 1 of the present invention;
[0033] Figure 3 The results of charge-discharge cycle tests of the composite positive electrode sheets of Example 3 and Comparative Example 2 are shown.
[0034] Figure 4 The images show SEM images of the composite positive electrode sheets of Example 1 and Comparative Example 1. Detailed Implementation
[0035] To further understand the present invention, it will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0036] Unless otherwise specified, the reagents used in the following description are commercially available products in the field, and the methods used are well-known in the field.
[0037] This invention provides a composite cathode sheet that can significantly improve the cycle performance of all-solid-state batteries. The proposed all-solid-state composite cathode sheet incorporates solid additives, terpenoid compounds (preferably camphene), which have minimal impact on charge and discharge and act as a binder in the cathode, resulting in better adhesion between active materials. This mitigates solid-solid contact loss during cycling and significantly improves the cathode capacity retention. A schematic diagram of the process for preparing the all-solid-state composite cathode sheet according to this invention is shown below. Figure 1 As shown, it includes the following steps:
[0038] S1. The positive electrode active material, solid electrolyte and conductive agent are mixed to obtain the first mixture;
[0039] S2. Under high temperature conditions, the additive (terpene compound) and the first mixture are mixed to obtain the second mixture;
[0040] S3. At room temperature, the PTFE binder and the second mixture are mixed to obtain the third mixture;
[0041] S4. The third mixture is fiberized and then shaped to obtain a self-supporting all-solid-state composite positive electrode sheet.
[0042] In the preparation of the above mixture, after obtaining the first mixture, additives are added and mixed at high temperature to melt and liquidate the additives, which helps to distribute the additives evenly and ensure sufficient contact with the components in the composite positive electrode. Direct mixing of the positive electrode active material, solid electrolyte, conductive agent, additives, and PTFE binder may result in fibrous agglomeration of the PTFE binder, which is detrimental to the uniform distribution of the components. Therefore, in this preparation process, the raw materials are added sequentially and mixed gradually as needed. Thus, as a preferred embodiment, the above-mentioned raw materials are added sequentially in the manner described above.
[0043] In this application:
[0044] The positive electrode active material is selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based oxide, sulfur, selenium, sulfides, selenides, and halide positive electrode materials; based on the first mixture, the content of the electrode active material is 68-78 wt%; more specifically, the positive electrode active material is selected from LiNi 0.8 Co 0.1 Mn 0.1 O2.
[0045] The solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; based on the first mixture, the content of the electrolyte powder is 19-29 wt%; more specifically, the solid electrolyte is selected from Li 5.5 PS 4.5 Cl 1.5 .
[0046] The conductive agent is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanofiber, carbon nanotube and graphene; based on the first mixture, the content of the conductive agent is 3 wt%; more specifically, the conductive agent is selected from carbon nanofiber.
[0047] The additive is selected from monoterpenes (C 10 H 16 ), sesquiterpenes (C15 H 24 ), diterpenes (C 20 H 32 The additive is selected from one or more terpenes, such as camphene; more specifically, the additive camphene is selected from bicyclic monoterpenes, and the content of the additive camphene is 3 wt% of the second mixture.
[0048] The PTFE binder is based on a third mixture and has a content of 0.5-2 wt%; more specifically, the content of the PTFE binder is 1 wt%.
[0049] This application fiberizes the third mixture to obtain a fibrous mixture; the fiberization method specifically involves applying shear force to the third mixture, and the device for applying shear force includes, but is not limited to, at least one of mixing equipment such as a ball mill, a mechanical mixer, and an air jet mill; in this application, manual grinding is used to apply the shear force; according to the present invention, the above-mentioned fibrous mixture is finally shaped to obtain a self-supporting positive electrode sheet. The shaping method described in this application is specifically multi-stage hot rolling.
[0050] As a preferred embodiment, the preparation method of the self-supporting composite positive electrode sheet of the present invention specifically comprises: using the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, solid electrolyte Li 5.5 PS 4.5 Cl 1.5 Conductive carbon nanofibers were mixed at room temperature for 20 minutes at a mass ratio of 68-78:19-29:3. Then, 3 wt% of molten camphene additive was added at 60°C and mixed evenly. After cooling to room temperature of 25°C, 1 wt% of PTFE binder was added to initially disperse it evenly. The PTFE binder was pre-fiberized by manual grinding for 25-35 minutes. After initial fiberization, the PTFE binder was formed into a self-supporting composite positive electrode film by multi-stage hot rolling at 120°C.
[0051] This application also provides an all-solid-state battery that achieves excellent long-cycle capacity retention, comprising a lithium indium alloy anode or a lithium titanate composite anode, a solid electrolyte membrane, and the aforementioned all-solid-state composite cathode.
[0052] It should be noted that the negative electrode of the battery prepared in this application may also be selected from silicon materials, graphite materials, hard carbon materials, soft carbon materials, doped carbon materials, composite materials composed of silicon and graphite, hard carbon, soft carbon or doped carbon, tin-based materials or alloy negative electrodes composed of indium, lithium, aluminum and at least two of the above metals; the battery prepared in this application may also be an all-solid-state sodium battery.
[0053] The following example uses all-solid-state lithium batteries:
[0054] All-solid composite positive electrode sheet
[0055] The all-solid-state composite positive electrode sheet in the all-solid-state battery provided in this application includes a positive electrode active material, a solid electrolyte, a conductive agent, a PTFE binder, and camphene as an additive. The positive electrode active material can be one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based oxide, sulfur, selenium, sulfides, selenides, and halide positive electrode materials. Specifically, the positive electrode active material is LiNi. 0.8 Co 0.1 Mn 0.1 O2. The solid electrolyte can be one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; specifically, the solid electrolyte is Li. 5.5 PS 4.5 Cl 1.5 The conductive agent can be one or more of carbon black, conductive graphite, carbon fiber, carbon nanofibers, carbon nanotubes, and graphene; specifically, the conductive agent is carbon nanofibers. The additive can be monoterpenes (C... 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 It contains one or more terpenes such as camphene; specifically, the additive is camphene, and the melting point of the additive camphene is between 48 and 52 °C.
[0056] Negative electrode sheet
[0057] The negative electrode includes a current collector and a negative electrode material disposed on the current collector. The negative electrode active material can be silicon, graphite, hard carbon, soft carbon, doped carbon, composite materials composed of silicon and graphite, hard carbon, soft carbon, or doped carbon, or tin-based materials. Graphite can include, but is not limited to, natural graphite (bulk graphite, flake graphite, amorphous graphite), artificial graphite (monocrystalline graphite, polycrystalline graphite, pyrolytic graphite, graphite fiber, etc.); silicon can include, but is not limited to, crystalline silicon, amorphous silicon, and organosilicon. The negative electrode can also be a self-supporting lithium titanate composite negative electrode, an alloy negative electrode composed of indium, lithium, aluminum, or at least two of the above metals. Furthermore, the negative electrode current collector can be copper foil, stainless steel foil, or other negative electrode current collectors commonly used in the art.
[0058] The specific preparation method of lithium titanate composite anode is as follows: lithium titanate (Li4Ti5O3) is used as the anode active material. 12 Solid electrolyte Li 5.5 PS 4.5 Cl 1.5Conductive carbon nanofibers were mixed at room temperature for 20 minutes in a mass ratio of 64:31:5. 1 wt% PTFE binder was added to initially disperse them evenly. The PTFE binder was pre-fiberized by manual grinding for 25 to 35 minutes. After initial fiberization, the mixture was formed into a self-supporting lithium titanate composite negative electrode film by multi-stage hot rolling at 120°C.
[0059] solid electrolyte layer
[0060] The solid electrolyte layer consists of a solid electrolyte and a binder. The solid electrolyte is one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; specifically, the solid electrolyte is Li. 5.5 PS 4.5 Cl 1.5 The binder is one or more of nitrile rubber, styrene-butadiene rubber, linear triblock copolymer, polyvinylidene fluoride, or polytetrafluoroethylene (PTFE), specifically, the binder is PTFE. The mass ratio of solid electrolyte to binder in the solid electrolyte layer is 90–99.5:0.5–10, specifically, Li… 5.5 PS 4.5 Cl 1.5 The mass ratio of PTFE to PTFE is 99.5:0.5.
[0061] All-solid-state batteries
[0062] The all-solid-state composite positive electrode, solid electrolyte layer, and negative electrode are sequentially placed into a mold for assembly. After assembly, pressure is applied and the nut at the top of the column is tightened to maintain a constant pressure, thus obtaining the all-solid-state battery. The assembly process is completed in a glove box under an argon atmosphere.
[0063] It should be noted that the all-solid-state battery prepared by the above method is an all-solid-state lithium battery. However, the battery prepared in this application can also be an all-solid-state sodium battery.
[0064] Those skilled in the art will understand that the battery preparation methods described above are merely embodiments. Other methods commonly used in the art can be employed without departing from the disclosure of this application.
[0065] The reagents and raw materials used in this invention are all commercially available.
[0066] This invention does not impose any special requirements on the assembly method of the aforementioned battery; any assembly method well-known to those skilled in the art can be used. Furthermore, the above-described technical solution is applicable not only to commonly used all-solid-state lithium batteries but also to various types of dynamic batteries such as all-solid-state sodium batteries.
[0067] The following are some specific embodiments and comparative examples to better illustrate this application.
[0068] Example 1
[0069] All-solid composite positive electrode sheet
[0070] The positive electrode active material LiNi was weighed according to a mass ratio of 68:29:3. 0.8 Co 0.1 Mn 0.1 O2, solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The conductive agent carbon nanofibers were manually ground and mixed at room temperature for 20 minutes. Then, 3 wt% molten camphene was added at 60°C and mixed evenly. After cooling to room temperature (25°C), 1 wt% PTFE binder was added to initially disperse the mixture evenly. The mixture was then manually ground for 25-35 minutes to pre-fiberize the PTFE binder. After initial fiberization, the mixture was subjected to multi-stage hot rolling at 120°C to form a self-supporting composite positive electrode membrane. The areal loading of the positive active material in this composite positive electrode is 27.5 mg / cm³. 2 .
[0071] like Figure 2 As shown, the composite positive electrode sheet prepared in this application does not require any other substrate for support or attachment and can achieve self-support.
[0072] Negative electrode sheet
[0073] The negative electrode is a lithium-indium alloy sheet (10mm in diameter).
[0074] solid electrolyte layer
[0075] Solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 It consists of a binder (PTFE) and an adhesive; the mass ratio of the two is 99.5:0.5.
[0076] All-solid-state lithium batteries
[0077] This all-solid-state lithium-ion battery consists of the aforementioned all-solid-state composite positive electrode, negative electrode, and solid electrolyte layer. The preparation steps are as follows:
[0078] The all-solid-state composite positive electrode, solid electrolyte layer, and lithium-indium alloy sheet are sequentially placed into a mold for assembly. After assembly, the pressure is increased to 50 MPa and the nut at the top of the column is tightened to maintain a constant pressure, thus obtaining the all-solid-state lithium battery. It should be noted that the assembly process is completed in a glove box under an argon atmosphere, and the diameters of the all-solid-state composite positive electrode, solid electrolyte layer, and lithium-indium alloy sheet are all 10 mm.
[0079] The assembled all-solid-state battery was subjected to cyclic testing under operating pressure of 50 MPa, temperature of 55 °C, and rate of 0.5 C.
[0080] Example 2
[0081] The preparation method is the same as in Example 1, except that the areal loading of the positive electrode active material in Example 2 is 32.6 mg / cm³. 2 The assembled all-solid-state battery was subjected to cycle testing under an operating pressure of 6 MPa, a temperature of 55°C, and a rate of 0.5C.
[0082] Example 3
[0083] The preparation method is the same as in Example 1, except that the areal loading of the positive electrode active material in Example 3 is 10.8 mg / cm³. 2 The assembled all-solid-state battery was subjected to cycle testing under an operating pressure of 6 MPa, a temperature of 30°C, and a rate of 0.5C.
[0084] Example 4
[0085] The preparation method is the same as in Example 1, except that the positive electrode active material in Example 4 is LiNi. 0.8 Co 0.1 Mn 0.1 O2, solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of carbon nanofibers to conductive agent is 78:19:3. The areal loading of the positive electrode active material is 24.7 mg / cm³. 2 .
[0086] In addition, the negative electrode is a lithium titanate composite negative electrode.
[0087] Lithium titanate (Li4Ti5O) is used as the negative electrode active material. 12 Solid electrolyte Li 5.5 PS 4.5 Cl 1.5 Conductive carbon nanofibers were mixed at room temperature for 20 minutes in a mass ratio of 64:31:5. 1 wt% PTFE binder was added to initially disperse them evenly. The PTFE binder was pre-fiberized by manual grinding for 25 to 35 minutes. After initial fiberization, the mixture was formed into a self-supporting lithium titanate composite negative electrode film by multi-stage hot rolling at 120°C.
[0088] The assembled all-solid-state battery was subjected to cycle testing under operating pressure of 2MPa, temperature of 30℃, and rate of 0.5C.
[0089] Example 5
[0090] The preparation method is the same as in Example 4, except that the areal loading of the positive electrode active material in Example 5 is 25.4 mg / cm³. 2 .
[0091] Example 6
[0092] The preparation method is the same as in Example 4, except that the areal loading of the positive electrode active material in Example 6 is 28.8 mg / cm³. 2 .
[0093] Compare with Example 1
[0094] The preparation method is consistent with that of Example 1, except that the all-solid-state composite positive electrode in Example 1 does not contain camphene (no additives are added during preparation), and the areal loading of the positive electrode active material is 39.4 mg / cm³. 2 .
[0095] Compare with Example 2
[0096] The preparation method is consistent with that of Example 1, except that the all-solid-state composite positive electrode in Comparative Example 2 does not contain camphene additive, and the areal loading of the positive electrode active material is 10.8 mg / cm³. 2 The assembled all-solid-state battery was subjected to cycle testing under an operating pressure of 6 MPa, a temperature of 30°C, and a rate of 0.5C.
[0097] Figure 3 The comparison of the charge-discharge performance of the composite positive electrode sheets prepared in Example 3 and Comparative Example 2 at a rate of 0.1C shows that introducing camphene into the composite positive electrode sheet does not reduce the charge-discharge specific capacity of the positive electrode.
[0098] Figure 4 The images show SEM images of the composite positive electrode sheets prepared in Example 1 and Comparative Example 1, respectively. The comparison shows that the addition of camphene can alleviate the solid-solid contact loss of the positive electrode active material and play a certain role in bonding.
[0099] Table 1 compares the cycle performance of the dry-prepared composite positive electrode sheets of Examples 1, 2, 3, 4, 5, 6, and Control Example 1 and Control Example 2. As can be seen from Examples 1 and 1, under the same conditions of 50 MPa, 55 °C, and 0.5 °C, the addition of camphene with an areal loading of 27.5 mg / cm³... 2 At that time, the capacity retention rate was 99.8% after 100 cycles, and the areal loading without camphene was 39.4 mg / cm³. 2 At that time, the capacity retention rate was 86.1% after 100 cycles, indicating that adding camphene to the composite cathode can improve the capacity retention rate; in addition, comparing Example 3 and Control Example 2, it can be seen that at an areal loading of 10.8 mg / cm³, 2When cycled at 6 MPa, 30°C and 0.5°C, Example 3 still achieved a capacity retention of 89.4% after 500 cycles, while Control Example 2 only achieved a capacity retention of 72.3% after 200 cycles. This indicates that the introduction of camphene at room temperature and low external pressure has a more significant effect. In addition, Examples 4 to 6 all show that even under a lower external pressure of 2 MPa, the introduction of camphene can also enable the all-solid-state battery to have a good capacity retention.
[0100] Table 1 Comparison of cycle performance of Examples 1-6 and Comparative Examples 1-2
[0101]
[0102]
[0103] In summary, the camphene-containing composite cathode electrode formulation and preparation process provided in this application enable the components within the all-solid-state composite cathode electrode to maintain close contact even after long-term cycling, thereby significantly improving the long-cycle performance of all-solid-state batteries operating at lower operating pressures.
[0104] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for preparing an all-solid-state composite positive electrode, characterized in that, Includes the following steps: S1: Mix the positive electrode active material, solid electrolyte and conductive agent to obtain the first mixture; S2: Under high temperature conditions, the additive terpenoid compound is mixed with the first mixture to obtain the second mixture; S3: Under low temperature conditions, the adhesive is mixed with the second mixture to obtain the third mixture; S4: The third mixture is fiberized and shaped to obtain the composite positive electrode sheet; In step S2, the high temperature condition is the temperature condition that makes the additive liquid; in step S3, the low temperature condition is the temperature condition that makes the additive solid. The additive terpenoid compounds act as binders in the positive electrode.
2. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S1, the positive electrode active material includes lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based oxide, sulfur, selenium, sulfides, selenides and halides; the mass fraction of the positive electrode active material in the first mixture is 68~78%.
3. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S1, the solid electrolyte includes oxide solid electrolyte, sulfide solid electrolyte and halide solid electrolyte; the mass fraction of the solid electrolyte in the first mixture is 19~29%.
4. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S1, the conductive agent includes carbon black, conductive graphite, carbon fiber, carbon nanofiber, carbon nanotube, and graphene; the mass fraction of the conductive agent in the first mixture is 3%.
5. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S2, the additive terpenoid compounds include monoterpenoid compounds, sesquiterpenoid compounds, and diterpenoid compounds; the mass fraction of the additive terpenoid compounds in the second mixture is 3-8%.
6. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S3, the adhesive includes PTFE; the mass fraction of the adhesive in the third mixture is 0.5~2%.
7. The method for preparing an all-solid-state composite positive electrode sheet according to claim 1, characterized in that, In step S4, the fiberization involves applying shear force to the third mixture, and the molding includes hot rolling.
8. A fully solid-state composite positive electrode, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 7.
9. The application of the all-solid-state composite positive electrode sheet as described in claim 8 in an all-solid-state battery.