Ex-situ rGO-ferroelectric composite material, composite current collector and preparation and application of composite current collector

Abstract

The invention belongs to the field of battery materials, and particularly relates to an ex-situ rGO-ferroelectric composite material which comprises an rGO nanosheet and a ferroelectric material physically compounded on the surface of the rGO nanosheet. The rGO nanosheet is obtained by freeze-drying a GO aqueous solution in advance and then performing two-stage gradient roasting treatment; the two-stage gradient roasting treatment comprises a low-temperature roasting process at the temperature of 500-700 DEG C and a high-temperature roasting process at the temperature of 750-1500 DEG C; the weight ratio of the rGO nanosheet to the ferroelectric material is 1: (0.3-10). The invention also comprises preparation of the material and application of the material in a battery and a current collector thereof. The freezing-two-stage gradient roasting mode and the condition combination are innovatively adopted, the rGO nanosheet with special physicochemical characteristics is obtained, the rGO nanosheet can accidentally adapt to the physicochemical characteristics of a ferroelectric material, uniform compounding of the ferroelectric material on the surface of the rGO nanosheet can be induced on the basis of a pure physical ex-situ mode, and the preparation method is simple and convenient. The problems of in-situ degradation, difficulty in reasonable control of physical and chemical properties and the like in in-situ preparation are not needed.

Description

Technical Field

[0001] This invention belongs to the field of preparation of electrode materials for secondary alkali metal batteries, specifically relating to a composite current collector and its preparation method. Background Technology

[0002] Secondary alkali metal batteries offer significant energy density advantages; for example, lithium metal batteries are considered the most ideal high-energy-density rechargeable batteries due to their attractive high specific capacity and lowest reduction potential. However, lithium dendrite behavior greatly reduces battery life and poses a serious challenge to the safety of secondary batteries, severely restricting the practical application of lithium metal batteries.

[0003] Studies have shown that the composition and properties of the SEI (Sediment Interlayer) significantly affect the deposition kinetics of lithium metal. SEIs derived from anion decomposition and rich in inorganic components such as LiF exhibit faster lithium-ion migration rates and superior mechanical properties, which is beneficial for constructing a more stable interface layer. Therefore, regulating the composition and properties of the SEI is of great significance for suppressing lithium dendrites and dead lithium, and improving the lifespan of lithium metal batteries.

[0004] The defective graphene structure of rGO can promote the adsorption and aggregation of anions in the electrolyte, thereby facilitating the formation of anion-derived, inorganic-rich SEI, which in turn promotes the transport of lithium ions at the interface and prevents the formation of lithium dendrites. Utilizing the spontaneous polarization characteristics of ferroelectric materials, it is expected that anions in the electrolyte can be continuously accumulated on the anode surface to compensate for the continuous consumption of SEI during battery operation.

[0005] Existing technologies have also reported a limited number of rGO / ferroelectric materials. For example, Indian patent publication number IN202321010042A provides a technique for in-situ synthesis of BATIO3 / P-RGO anode materials to enhance the electrochemical performance of recycled graphite in lithium-sulfur batteries. Chinese patent publication number CN106532016A also discloses a composite cathode material for lithium-sulfur batteries and its preparation method, specifically describing a scheme that uses graphene oxide as the matrix of the battery cathode material, and combines graphene oxide with ferroelectric materials through hydrothermal preparation (i.e., in-situ) to obtain a graphene / ferroelectric composite material.

[0006] In summary, all existing rGO ferroelectric composite materials are in-situ composite materials. However, during the in-situ composite process, rGO and ferroelectric materials are prone to mutual degradation, and the physicochemical properties of the materials are difficult to control precisely. This results in relatively random quality of in-situ composite materials, and it is difficult to guarantee their electrochemical performance and quality stability. Summary of the Invention

[0007] To address the problems existing in the prior art, the primary objective of this invention is to provide a non-in-situ rGO-ferroelectric composite material, aiming to provide a physical composite material with the same rGO-ferroelectric properties.

[0008] The second objective of this invention is to provide the preparation and application of the aforementioned non-in-situ rGO-ferroelectric composite material.

[0009] A third objective of this invention is to provide a composite current collector comprising the aforementioned non-in-situ rGO-ferroelectric composite material, and its preparation and application.

[0010] A fourth objective of the present invention is to provide a battery comprising the aforementioned composite current collector.

[0011] To address the problems of degradation of rGO and ferroelectric materials during the in-situ composite stage and the difficulty in reasonably controlling the physicochemical structure, leading to unsatisfactory electrochemical performance and quality stability of the materials, this invention attempts to provide a material with direct rGO-ferroelectric physical composite. However, early research showed that rGO and ferroelectric materials are difficult to assemble in-situ due to differences in their physicochemical properties. To address this problem, this invention, after in-depth research, provides the following improvement scheme:

[0012] A non-in-situ rGO-ferroelectric composite material, comprising rGO nanosheets and ferroelectric materials physically composited on their surface;

[0013] The rGO nanosheets were obtained by pre-freezing an aqueous GO solution followed by a two-stage gradient calcination process.

[0014] The two-stage gradient roasting process includes a low-temperature roasting process of 500–700°C and a high-temperature roasting process of 750–1500°C.

[0015] The weight ratio of the rGO nanosheets to the ferroelectric material is 1:0.3 to 10.

[0016] This invention innovatively employs a combination of freezing-two-stage gradient calcination methods and conditions to obtain rGO nanosheets with unique physicochemical properties. These nanosheets unexpectedly adapt to the physicochemical characteristics of ferroelectric materials, allowing for the induction of uniform composite formation of ferroelectric materials on their surface through a purely physical, non-in-situ method. This avoids the problems of in-situ degradation and difficulty in controlling physicochemical properties encountered in in-situ preparation. Furthermore, the non-in-situ material described in this invention can optimize the physicochemical synergy between the two materials, synergistically enhancing electrochemical performance. Compared to in-situ preparation methods, our synthesized rGO-ferroelectric composite material allows for more precise control of the intrinsic properties of rGO and ferroelectric materials. For example, the morphology, specific surface area, defect rate, and conductivity of rGO, as well as the size, morphology, ferroelectricity, and surface dipoles of the ferroelectric materials, can all be individually and accurately controlled, better achieving the design expectations.

[0017] In this invention, the concentration of GO in the GO aqueous solution is 1-5 g / L.

[0018] In this invention, the GO aqueous solution is frozen into ice blocks and then subjected to subsequent freeze-drying treatment, wherein the freezing temperature is below -10°C. For example, it can be frozen in the freezer compartment of a refrigerator.

[0019] In this invention, the freezing process is a process of rapidly cooling the GO aqueous solution in a cooling medium with a boiling point below -100°C.

[0020] The present invention demonstrates that pre-cooling the GO aqueous solution followed by freeze-drying and two-stage gradient treatment can further optimize the physicochemical properties of rGO, thereby improving its compatibility with ferroelectric materials, enhancing the uniformity and integrity of the non-in-situ assembly, and further strengthening the synergistic effect of the materials.

[0021] In this invention, the cooling medium is at least one of liquid nitrogen and dry ice.

[0022] In this invention, there are no special requirements for the freeze-drying time, as long as the moisture is removed. For example, the time can be more than 5 hours, and more specifically 10 to 40 hours.

[0023] In this invention, the atmosphere during the two gradient calcination stages is a protective atmosphere.

[0024] In this invention, the protective atmosphere includes at least one of nitrogen and an inert gas.

[0025] In this invention, the protective atmosphere may also contain hydrogen.

[0026] In this invention, the low-temperature calcination temperature can be 550–600°C.

[0027] In this invention, the low-temperature calcination time t1 is 0.5 to 5 hours, and can be further 1 to 2 hours.

[0028] In this invention, the high-temperature calcination temperature can be 800–900°C.

[0029] In this invention, the high-temperature calcination time t2 is 0.5 to 5 hours, and can be further 1 to 2 hours.

[0030] In the present invention, the two-stage gradient calcination is carried out under a slightly negative pressure. The slightly negative pressure refers to a pressure of 0.01 - 0.5 atm. In the present invention, through the two-stage calcination treatment under slightly negative pressure, it can help to strengthen the physical and chemical characteristics such as ID / IG of rGO, further strengthen its non-in-situ assembly structure with ferroelectric materials, and contribute to further strengthening the combined synergy between the two.

[0031] In the present invention, the ferroelectric materials include LiNbO3, Na x K y NbO3 (0 < x < 1, y = 1 - x), BiFeO3, PbZr x Ti y O3 (0 < x < 0.5, y = 1 - x), Bi4Ti3O 12 , KTa x Nb y O3 (0 < x < 0.5, y = 1 - x), BaTiO3, (Ba x1 [[ID=^{19}]]Ca y1 Sr z1 )(Ti x2 Zr y2 Sn z2 )O3 (0.5 < x1 < 1, 0 < y1, 0 < z1, y1 + z1 = 1 - x1; 0.5 < x < 2, 0 < y2, 0 < z2, y2 + z2 = 1 - x2), and at least one of them. Preferably, the ferroelectric material is LiNbO3 and BiFeO3 with a weight ratio of 1:0.5 - 2. Research shows that the preferred ferroelectric material and rGO described in the present invention can obtain better synergy and further strengthen the performance of the material.

[0032] In the present invention, the weight ratio of the rGO nanosheets to the ferroelectric material is 1:0.5 - 5; further, it can be 1:2.5 - 3.5. Research shows that at the preferred ratio, the physical assembly advantage of rGO and the ferroelectric material can be further improved, and the combined synergy effect of the physical materials can be further strengthened.

[0033] The research of the present invention also shows that by jointly controlling the quality of rGO nanosheets and ferroelectric materials, the non-in-situ assembly effect of the two can be further strengthened, which helps to further strengthen their synergy performance.

[0034] The present invention also provides a preparation method for the non-in-situ rGO-ferroelectric composite material, which is prepared by slurrying the rGO and the ferroelectric material with a solvent and physically assembling them.

[0035] In this invention, the solvent can be any organic solvent, such as at least one of N-methylpyrrolidone (NMP), N,N-dimethylamide (DMF), and dimethyl sulfoxide (DMSO).

[0036] The present invention also provides a composite current collector, which includes a current collector substrate and a modified layer loaded on its surface; the modified layer includes the aforementioned non-in-situ rGO-ferroelectric composite material and also contains a binder.

[0037] The current collector substrate can be a planar metal current collector, including at least one of copper foil, carbon-coated copper foil, aluminum foil, coated aluminum foil, titanium foil, carbon-coated titanium foil, zinc foil, and carbon-coated zinc foil.

[0038] The adhesive may be a conventional component in the industry, such as at least one of PVDF, PVDF-HFP, P(VDF-TrFE-CTFE), and SBR.

[0039] In the modified layer, the weight ratio of the non-in-situ rGO-ferroelectric composite material to the binder is 5 to 20:1; more specifically, it can be 8 to 14:1.

[0040] The present invention also provides a method for preparing the composite current collector described above, wherein the non-in-situ rGO-ferroelectric composite material and the binder are slurried with a solvent and coated onto the current collector substrate, and then dried to obtain the current collector.

[0041] For example, its preparation steps can be:

[0042] An adhesive solution is prepared by stirring an adhesive such as PVDF in a solvent.

[0043] Ferroelectric material powder is placed in a solvent and ultrasonically treated to obtain a ferroelectric powder suspension.

[0044] rGO powder was placed in the above ferroelectric powder suspension and stirred continuously to obtain a mixed slurry of ferroelectric powder and rGO powder.

[0045] The prepared adhesive solution is placed in the above-mentioned mixed slurry and stirred continuously to obtain the final slurry to be coated.

[0046] The prepared slurry was coated onto copper foil and dried to obtain a composite current collector.

[0047] The present invention also provides a negative electrode-free battery comprising the aforementioned composite current collector.

[0048] Beneficial effects

[0049] This invention employs a combination of freezing-two-stage gradient calcination methods and conditions to obtain rGO nanosheets with unique physicochemical characteristics (such as defects in ferroelectric material adaptation and layered structures). These nanosheets unexpectedly adapt to the physicochemical characteristics of ferroelectric materials, allowing for the uniform assembly and composite formation of ferroelectric materials on their surface through a purely physical, non-in-situ method. The non-in-situ material described in this invention can optimize the physicochemical synergy between the two materials, synergistically enhancing electrochemical performance. Attached Figure Description

[0050] Figure 1 The image shows the XRD pattern of the rGO material prepared in Example 1.

[0051] Figure 2 An optical photograph of the composite current collector prepared in Example 1.

[0052] Figure 3 The image shows a surface SEM image of the composite current collector prepared in Example 1.

[0053] Figure 4 The image shows a cross-sectional SEM image of the composite current collector prepared in Example 1.

[0054] Figure 5 The morphology of lithium deposition when pure copper foil is used as the current collector.

[0055] Figure 6 The morphology of the deposited lithium in the composite current collector prepared in Example 1.

[0056] Figure 7 Coulombic efficiency test of Li-Cu battery assembled with pure copper foil as current collector.

[0057] Figure 8 Coulombic efficiency test of Li-Cu@rGO-BTO battery assembled with composite current collector prepared in Example 1.

[0058] Figure 9 The time-voltage curves of the prepared Cu@Li / / Cu@Li cells are shown.

[0059] Figure 10 The time-voltage curves are shown for the Cu@rGO-BTO@Li / / and Cu@rGO-BTO@Li batteries prepared in Example 1. Detailed Implementation

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0061] Example 1

[0062] Step 1: Preparation of rGO

[0063] Step 1a: Freeze a 2 g / L GO aqueous solution in a refrigerator at -10 to -20°C for 10 to 12 hours, and then freeze-dry it for 30 hours to obtain flocculent GO;

[0064] Step 1b: The flocculent GO was first heated to a low temperature of 600℃ for 1 hour under a high-purity Ar atmosphere, and then heated to a high temperature of 800℃ for 1 hour at a rate of 2℃ / min. Finally, it was cooled in the furnace to obtain the rGO product.

[0065] Step 2: In-situ assembly and current collector preparation

[0066] PVDF powder was dissolved in NMP solvent at a 5% solution concentration and mechanically stirred for 24 hours to obtain an adhesive solution. BaTiO3 (ferroelectric powder) was placed in NMP and ultrasonically treated for 3 hours to obtain a ferroelectric suspension, wherein m(ferroelectric powder):m(NMP) = 1 / 5. The rGO powder obtained in step 1 was placed in the above ferroelectric suspension at a mass ratio of m(rGO):m(ferroelectric powder) = 1 / 3, and ball-milled and mechanically stirred for 15 minutes to obtain rGO. A slurry of PVDF and ferroelectric powder was prepared. An appropriate amount of PVDF binder solution was added to the slurry at a ratio of m(PVDF):m(rGO + ferroelectric powder) = 1 / 12, and the mixture was further stirred by ball milling to obtain the final slurry to be coated. A wet film thickness of 30 micrometers was selected, and the obtained slurry was coated onto copper foil using a doctor blade. The foil was then placed in an 80°C forced-air oven for 1 hour for rapid drying. The product was then placed in a 65°C vacuum oven for 12 hours to obtain the final composite current collector.

[0067] test:

[0068] The obtained composite current collector and lithium foil were assembled into a 2016 coin cell (labeled as Li-Cu@rGO-BTO cell), wherein the separator was a PP (2500 type) separator and the electrolyte was a 1M concentration of LiTFSI lithium salt + (DOL:DME = 1:1 volume ratio solvent).

[0069] Alternatively, as a reference, the Cu@rGO-BTO was replaced with copper foil (the copper foil described in step 2), and the coin cell (labeled as Li-Cu cell) was assembled in the same manner.

[0070] Lithium with a capacity of 10 mAh / cm² was deposited on Cu foil and Cu@rGO-BTO, respectively, to obtain Cu@Li and Cu@rGO-BTO@Li electrodes.

[0071] The obtained Cu@Li and Cu@rGO-BTO@Li electrodes were assembled into 2016 coin-type symmetric cells (labeled Cu@Li / / Cu@Li and Cu@rGO-BTO@Li / / Cu@rGO-BTO@Li cells, respectively). The separator was a PP (2500 type) membrane, and the electrolyte was a 1M concentration of LiTFSI lithium salt + (DOL:DME = 1:1 volume ratio solvent). The cells operated at 1 mA / cm². 2 -1mAh / cm 2 The testing system is in operation.

[0072] Figure 2 An optical photograph of the composite current collector after it has been cut into pieces; Figure 3 The surface morphology of the prepared composite current collector shows that BaTiO3 ferroelectric powder is uniformly distributed on the rGO surface; Figure 4 Based on the cross-sectional morphology of the corresponding composite current collector, the thickness of the composite coating is approximately 5 micrometers. (Based on 1 mA / cm²) 2 The current density was 4 mA / cm² for deposition on pure copper foil and composite current collector, respectively. 2 Lithium plating, Figure 6 The morphology of the deposited lithium in the prepared composite current collector shows that the deposited lithium surface is smooth and dense, without dendrites, while the deposited lithium when pure copper foil is used as the current collector has a dendritic morphology, and the surface is rough and loose. Figure 5 Furthermore, the Li-Cu battery assembled using pure copper foil as the current collector has low coulombic efficiency and can only achieve stable cycling (stable cycling refers to a coulombic efficiency greater than 98%; the same applies below) for approximately 160 cycles. Figure 7 The Li-Cu@rGO-BTO battery assembled with the prepared composite current collector exhibits higher coulombic efficiency and can be stably cycled (stable cycling refers to a coulombic efficiency greater than 98%; the same below) for more than 300 cycles. Figure 8 The prepared Cu@rGO-BTO@Li / / and Cu@rGO-BTO@Li batteries can be stably cycled (at a voltage less than 50mV) for 2000 hours. Figure 10 The Cu@Li / / Cu@Li battery only operates stably for 1000 hours. Figure 9 ).

[0073] Example 2:

[0074] Compared with Example 1, the only difference is that in step 1a, the GO aqueous solution is pre-mixed with liquid nitrogen and subjected to rapid cooling, followed by freeze drying to obtain the flocculent GO. All other operations and parameters are the same as in Example 1.

[0075] Example 3:

[0076] Compared with Example 1, the only difference is that in step 1b, the low-temperature calcination temperature is 550°C and the time is 2 hours, while the high-temperature calcination temperature is 900°C and the time is 1 hour. All other operations and parameters are the same as in Example 1.

[0077] Example 4:

[0078] Compared with Example 1, the only difference is that in step 1b, the system pressure during the heating process and the heat preservation process of low-temperature calcination and high-temperature calcination is controlled at 0.1 to 0.3 atm (atm refers to standard atmospheric pressure). All other operations and parameters are the same as in Example 1.

[0079] Example 5:

[0080] Compared to Example 1, the only difference is that the type of ferroelectric material was changed; the experimental groups were as follows:

[0081] Group A: The ferroelectric material is LiNbO3;

[0082] Group B: The ferroelectric material is BiFeO3;

[0083] Group C: Ferroelectric materials are LiNbO3 and BiFeO3 in a weight ratio of 1:1;

[0084] All other operations and parameters are the same as in Example 1.

[0085] Example 6:

[0086] Compared to Example 1, the only difference is that the ratio of ferroelectric material to rGO was changed (the total amount of both remained the same). The experimental groups were as follows:

[0087] Group A: The weight ratio of rGO and ferroelectric materials is 1:5, and the weight ratio of PVDF to (ferroelectric materials + rGO) is 1:10.

[0088] Group B: The weight ratio of rGO to ferroelectric materials is 1:0.5;

[0089] All other operations and parameters are the same as in Example 1.

[0090] Comparative Example 1:

[0091] Compared with Example 1, the only difference is that GO is not subjected to the freeze-freeze drying process described above, but is directly used as raw material for step 1b. All other operations and parameters are the same as in Example 1.

[0092] Comparative Example 2:

[0093] Compared with Example 1, the only difference is that in step 1b, the high-temperature roasting temperature and the low-temperature roasting temperature are the same, both being 600°C, while other operations and parameters are the same as in Example 1.

[0094] Comparative Example 3:

[0095] Compared with Example 1, the only difference is that in step 1b, the high-temperature roasting temperature and the low-temperature roasting temperature are the same, both being 800°C, while other operations and parameters are the same as in Example 1.

[0096] Comparative Example 4:

[0097] Compared with Example 1, the only difference is that the weight ratio of rGO to ferroelectric material is 1:12 (the total amount of both remains unchanged), and all other operations and parameters are the same as in Example 1.

[0098] Comparative Example 5:

[0099] Compared to Example 1, the only difference is that the rGO product obtained in step 1 was dispersed in water with barium nitrate and ethyl titanate (Ba / Ti molar ratio of 1:1, and the weights of rGO and the designed barium titanate were the same as in Example 1), and then hydrothermally heated at 160°C for 5 hours to obtain the composite material. This composite material was then used to replace the BaTiO3 and rGO physical composite in Example 1, and combined with PVDF to obtain the composite current collector. All other operations and parameters were the same as in Example 1.

[0100] Table 1:

[0101]

[0102]

[0103] Table 2

[0104]

[0105] As can be seen from Tables 1 and 2, the preparation method of rGO described in this invention can facilitate the uniform physical assembly of ferroelectric materials, solve the degradation problem encountered in the in-situ preparation process, and achieve more ideal results.

[0106] Furthermore, as shown in Examples 1 and 2, rGO obtained using a rapid quenching process is more conducive to the physical composite assembly of ferroelectric materials, resulting in superior performance. Additionally, as shown in Examples 1 and 4, rGO obtained by calcination under slight negative pressure is also beneficial to the physical composite assembly of ferroelectric materials. As shown in Examples 1 and 5, the ferroelectric materials using the combination described in this invention unexpectedly exhibit superior physical assembly synergy.

Claims

1. A non-in-situ rGO-ferroelectric composite material, characterized in that, This includes rGO nanosheets and ferroelectric materials physically composited on their surface; The rGO nanosheets were obtained by pre-freezing an aqueous GO solution followed by a two-stage gradient calcination process. The two-stage gradient roasting process includes a low-temperature roasting process of 500–700°C and a high-temperature roasting process of 750–1500°C. The weight ratio of the rGO nanosheets to the ferroelectric material is 1:0.3 to 10.

2. The non-in-situ rGO-ferroelectric composite material as described in claim 1, characterized in that, In the GO aqueous solution, the concentration of GO is 1-5 g / L; Preferably, the GO aqueous solution is frozen into ice blocks and then subjected to subsequent freeze-drying treatment, wherein the freezing temperature is below -10°C.

3. The non-in-situ rGO-ferroelectric composite material as described in claim 2, characterized in that, The freezing process is a process of rapidly cooling the GO aqueous solution in a cooling medium with a boiling point below -100°C; Preferably, the cooling medium is at least one of liquid nitrogen and dry ice; Preferably, the freeze-drying time is more than 5 hours.

4. The non-in-situ rGO-ferroelectric composite material as described in claim 1, characterized in that, The atmosphere during the two-stage gradient roasting process is a protective atmosphere; Preferably, the protective atmosphere includes at least one of nitrogen and an inert gas; Preferably, the protective atmosphere may also contain hydrogen; Preferably, the low-temperature calcination time t1 is 0.5 to 5 hours; Preferably, the high-temperature calcination time t2 is 0.5 to 5 hours.

5. The non-in-situ rGO-ferroelectric composite material as described in claim 1, characterized in that, The two-stage gradient calcination process was carried out under slight negative pressure. Preferably, the micro-negative pressure refers to a pressure of 0.01 to 0.5 atm.

6. The non-in-situ rGO-ferroelectric composite material as described in claim 1, characterized in that, The ferroelectric materials mentioned include LiNbO3 and Na. x K y NbO3(0 <x<1,y=1-x)、BiFeO3、PbZr x Ti y O3(0 <x<0.5,y=1-x)、Bi4Ti3O 12 KTa x Nb y O3(0 <x<0.5,y=1-x)、BaTiO3、 (Ba x1 Ca y1 Sr z1 )(Ti x2 Zr y2 Sn z2 )O3 (where 0.5 < x1 < 1, 0 < y1, 0 < z1, y1 + z1 = 1 - x1; 0.5 < x2 < 1, 0 < y2, 0 < z2, y2 + z2 = 1 - x2); preferably LiNbO3 and BiFeO3 with a weight ratio of 1:0.5 to 2.

7. A method for preparing the non-in-situ rGO-ferroelectric composite material according to any one of claims 1 to 6, characterized in that, The rGO and ferroelectric materials were prepared by solvent slurrying and physical assembly.

8. A composite current collector, characterized in that, It includes a current collector substrate and a modified layer on its surface; the modified layer includes the non-in-situ rGO-ferroelectric composite material according to any one of claims 1 to 6, and further includes a binder; Preferably, the current collector substrate is a planar metal current collector, including at least one of copper foil, carbon-coated copper foil, aluminum foil, coated aluminum foil, titanium foil, carbon-coated titanium foil, zinc foil, and carbon-coated zinc foil; Preferably, the adhesive comprises at least one of PVDF, PVDF-HFP, P(VDF-TrFE-CTFE), and SBR; Preferably, in the modified layer, the weight ratio of the non-in-situ rGO-ferroelectric composite material to the binder is 5 to 20:1; more preferably, it can be 8 to 14:

1.

9. A method for preparing the composite current collector according to claim 8, characterized in that, The non-in-situ rGO-ferroelectric composite material and binder are slurried with solvent and then coated onto the current collector substrate, followed by drying to obtain the final product.

10. A negative electrode-free battery, characterized in that, It includes the composite current collector as described in claim 9.

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