Modified self-supporting array current collector, method for preparing same, use thereof, and negative electrode-free battery

Abstract

This invention belongs to the field of batteries, specifically relating to a modified self-supporting array current collector, its preparation method, applications, and a negative electrode-free battery. The modified self-supporting array current collector includes a planar metal current collector, a functional material array composited on the surface of the planar metal current collector, and a polymer electrolyte in situ composited in the gaps and surface of the functional material array. The functional material array comprises one-dimensional functional materials arrayed along the height direction of the planar metal current collector; these functional materials are ferroelectric materials. This invention innovatively forms the functional array on the current collector and innovatively forms the polymer electrolyte in situ within the functional array. Research has found that this special modified electrolyte can adapt to the charge and discharge characteristics of a negative electrode-free battery, simplifying the battery structure and improving energy density and performance.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, specifically relating to the field of negative electrode-free battery technology. Background Technology

[0002] With the rapid development of new energy, electric transportation, and large-scale energy storage technologies, the demand for high-energy-density, high-safety, and long-cycle-life secondary battery systems is increasing. Alkali metal secondary batteries, especially those using lithium, sodium, or potassium metals as anodes, are considered an important development direction for achieving high-energy-density batteries due to their high theoretical specific capacity and low electrode potential. However, in practical applications, alkali metal anodes are prone to problems such as uneven metal deposition, severe interface polarization, and significant volume changes during repeated charge-discharge cycles, leading to a series of adverse effects such as interface contact failure, dendrite growth, and decreased cycle stability. Especially in anode-free secondary battery systems, since there is no pre-placed anode active material matrix in the initial state, the initial nucleation and subsequent deposition / stripping behavior of alkali metals depend entirely on the exposed current collector surface. This leads to a more extreme "infinite" volume change rate for anode-free batteries. Once dendrite piercing or dead metal (such as dead lithium / dead sodium) falls off, it will not only cause an irreversible reduction in capacity, but also cause serious safety hazards. This makes interface instability the biggest bottleneck restricting the commercialization of anode-free batteries.

[0003] To alleviate the aforementioned problems, existing technologies mainly focus on current collector structure design, electrolyte material modification, and interface control. For example, constructing three-dimensional porous, foam-like, or array-type current collector structures can reduce local current density to some extent and provide a physical confinement space for metal deposition; introducing solid or gel-like electrolytes can improve battery safety and interface stability. However, the aforementioned three-dimensional structures in existing technologies often exhibit random stacking or disordered distribution characteristics, making it difficult to precisely control their pore size, spatial connectivity, and ion transport paths, resulting in strong randomness in metal deposition behavior. Furthermore, existing technologies typically cover the surface of the three-dimensional current collector with solid or semi-solid electrolytes through physical pressing, coating, or casting. Due to the geometric complexity within the three-dimensional structure, the electrolyte cannot deeply wet to the bottom of the pores, leading to the generation of numerous microscopic "dead zones" (air gap structures). This simple "split-type" physical contact results in extremely high interfacial impedance, and during long-term cycling, the drastic volume expansion and contraction associated with alkali metal deposition / stripping easily leads to interfacial debonding or contact degradation between the electrolyte and the current collector, making it difficult to maintain a stable coupling relationship over a long period. Furthermore, existing three-dimensional structural designs often focus on geometric confinement, primarily mitigating dendrite growth by reducing local current density. However, they lack effective means to control the distribution of local electric fields at the interface and the direction of ion flux, which may still lead to uneven alkali metal deposition under high-rate or long-cycle conditions.

[0004] Furthermore, ferroelectric materials, due to their spontaneous polarization properties, can form built-in electric fields within the material or at the interface, and are considered to have potential advantages in regulating ion migration behavior. However, existing studies mostly treat ferroelectric materials as zero-dimensional particle fillers, randomly dispersed in electrode / electrolyte systems, or as two-dimensional thin layers coated at the interface. The built-in electric field of zero-dimensional particles is randomly distributed, and there is a phenomenon of mutual polarization cancellation, making it difficult to guide the macroscopic ion flux in a long-range, ordered manner; two-dimensional thin layers lack sufficient physical space to accommodate the huge volume changes of anode-less batteries, making it difficult to fully utilize their advantages in alkali metal deposition regulation. Therefore, there is an urgent need to propose a new anode structure design approach that, while achieving the advantages of ordered array confined structures, introduces a tunable polarization environment, and achieves integrated construction of the anode and electrolyte through synergistic design of structure and materials. This would allow for synergistic regulation of alkali metal deposition and stripping behavior at the microscale, improving the cycle stability and safety of the battery. Summary of the Invention

[0005] To address the problems existing in current collectors for electrodeless batteries, the primary objective of this invention is to provide a modified self-supporting array current collector adapted to the characteristics of electrodeless batteries, aiming to improve the energy density, metal deposition reversibility, long-cycle stability, and high safety performance of electrodeless batteries, and fundamentally suppress the serious dendrite growth and interface failure problems in electrodeless systems.

[0006] The second objective of this invention is to provide the modified self-supporting array current collector and its application in a negative electrode-free battery.

[0007] A third objective of this invention is to provide a negative electrode-free battery comprising the modified self-supporting array current collector.

[0008] Anode-free batteries, compared to traditional lithium / sodium-ion batteries, are characterized by the fact that, in the assembled state, the negative electrode side is merely an exposed current collector, containing no pre-placed active negative electrode substrate material (such as graphite, silicon, or alkali metal foil). All alkali metals participating in the electrochemical reaction originate from the extraction of the positive electrode material during the first charge. While this unique system significantly improves the battery's energy density, it also presents extremely stringent and specific processing challenges.

[0009] (1) "Infinite" volume expansion: Since the initial state of the negative electrode active material is zero, the deposition of alkali metal on the two-dimensional plane current collector during charging will cause the local volume change rate to tend to be infinite, which is very easy to destroy the fragile solid electrolyte interface (SEI) or crush the solid electrolyte layer of the conventional interface.

[0010] (2) Zero metal redundancy and extremely low coulombic efficiency: Without a negative electrode system, there is no additional active metal. Once the alkali metal forms an electrically isolated "dead metal (such as dead lithium / dead sodium)" during repeated deposition / stripping or is excessively consumed by side reactions, the battery capacity will experience a cliff-like decline.

[0011] (3) High nucleation barrier and intense dendrite growth: In the absence of the guidance of the host matrix, alkali metal ions tend to nucleate unevenly at the micro-defects on the surface of the current collector, and then rapidly evolve into sharp dendrites in the subsequent deposition, which can easily pierce the diaphragm or electrolyte and cause short circuits.

[0012] (4) Dynamic peeling of the interface: The violent volume expansion and contraction will cause physical gaps (contact deterioration) to be continuously generated between the deposited metal and the conventionally covered electrolyte, resulting in a sharp increase in interface impedance.

[0013] To address the unique challenges of the aforementioned negative electrode-free battery system, this invention provides the following solution:

[0014] Modified self-supporting array current collectors include planar metal current collectors, functional material arrays composited on the surface of planar metal current collectors, and polymer electrolytes in situ composited in the gaps (slots) and surfaces of functional material arrays.

[0015] The functional material array comprises one-dimensional functional materials arranged in an array along the height direction of the planar metal current collector; the functional material is a ferroelectric material.

[0016] In the present invention, the functional array is innovatively formed on the current collector, and the polymer electrolyte is innovatively formed in-situ in the functional array. It has been found that this special modified electrolyte can adapt to the charge-discharge characteristics of the non-anode battery, simplify the battery structure, improve the energy density, and bring the following synergistic properties and effects significantly different from the traditional system in the non-anode battery system:

[0017] First, strong physical confinement and zero-stress deposition: The vertically aligned one-dimensional array structure provides a sufficient and regular three-dimensional accommodation space for the "from scratch" deposition of alkali metals in the non-anode battery, effectively alleviating the macroscopic volume expansion stress and preventing mechanical damage to the electrolyte interface;

[0018] Second, spontaneous polarization guides uniform nucleation: Due to its spontaneous polarization characteristics, the one-dimensional ferroelectric material constructs a highly ordered and uniformly directed local built-in electric field inside the array pores. This electric field can equalize the ion flux in the pores, eliminate the electric field tip effect, and actively guide the uniform and dense nucleation and growth of alkali metal ions at the bottom and side walls of the array, completely eradicating the generation of dendrites from both the thermodynamic and kinetic dimensions;

[0019] Third, 3D continuous interface and extremely low impedance: This structure is conducive to forming a polymer electrolyte by infiltrating the precursor solution into the array pores and in-situ polymerization, facilitating the "dead-angle-free" deep embedding of the solid polymer electrolyte and the one-dimensional ferroelectric array. This integrated structure eliminates the interfacial air gaps brought by the traditional coating process, ensuring that during the剧烈 volume change process of the non-anode battery, a tight and continuous ion transport channel is always maintained between the current collector, alkali metal, and electrolyte, greatly reducing the interfacial impedance and significantly improving the Coulomb efficiency and cycle life.

[0020] In the present invention, the planar metal current collector includes a metal current collector, and its materials include but are not limited to at least one of copper, nickel, and stainless steel.

[0021] In the present invention, the ferroelectric materials include at least one of barium titanate, lead zirconate titanate, strontium titanate, sodium bismuth titanate, potassium bismuth titanate, strontium bismuth titanate, calcium bismuth titanate, lanthanum bismuth titanate, iron bismuth titanate, barium zirconate titanate, strontium zirconate titanate, bismuth titanate, lithium niobate, sodium niobate, lithium tantalate, sodium tantalate, bismuth ferrite, bismuth titanium oxide, bismuth manganese oxide; further, it can be BaTi 1-x Zr x O3, where 0 < x < 1. Preferably, BaTi 1-x Zr x O3 can be combined with the structure described in the present invention to obtain better performance.

[0022] In this invention, the functional material is a doped and modified ferroelectric material; and / or a ferroelectric material coated with a modifier. Research in this invention shows that the modified ferroelectric material, combined with the overall structure described in this invention, helps to further optimize the interfacial interaction between the array and the electrolyte, and helps to further improve the electrochemical performance of the negative electrode-free battery.

[0023] The doped ferroelectric material includes at least one doping element selected from lanthanum (La), strontium (Sr), calcium (Ca), niobium (Nb), tantalum (Ta), zirconium (Zr), iron (Fe), manganese (Mn), cobalt (Co), magnesium (Mg), aluminum (Al), yttrium (Y), neodymium (Nd), or cerium (Ce), and the content of the doping element is 0.5~8 mol%, more preferably 2~5 mol%;

[0024] In ferroelectric materials coated with a modifier, the modifier includes at least one selected from silane coupling agents, titanate coupling agents, and transition metal oxides; and the content of the modifier is 1~6 wt.%. Alternatively, the thickness of the modifier is ≤10 nm; more specifically, it can be 2~8 nm. The transition metal oxide is, for example, zinc oxide.

[0025] In this invention, the cross-section of the one-dimensional functional material is at least one of a cube, cuboid, cylinder, hexagon, etc.

[0026] The one-dimensional functional material described in this invention can be a linear one-dimensional material or a non-linear one-dimensional material.

[0027] As an optional configuration, the planar dimensions of the one-dimensional functional materials in the array are 10 nm to 100 μm, preferably 200 nm to 5 μm, and more preferably 200 to 500 nm. The array height is 0.5 to 100 μm, preferably 2 to 30 μm, and more preferably 5 to 15 μm. The spacing between the one-dimensional functional materials is 10 nm to 50 μm, preferably 100 nm to 10 μm, and more preferably 150 to 300 nm.

[0028] Preferably, the surface and / or bulk phase of the one-dimensional functional material further includes a pore structure of at least one of micropores and mesopores, and the porosity is 5-60%, preferably 10-40%; more preferably 20-30%.

[0029] In this invention, constructing a certain porous structure on the array material helps to further improve its interfacial interaction with the electrolyte and further enhance the electrochemical performance of the negative electrode-free battery.

[0030] In this invention, the polymer electrolyte is obtained by in-situ polymerization of a solution containing monomers, crosslinking agents, initiators, and conductive alkali metal salts.

[0031] The present invention also provides a method for preparing the modified self-supporting array current collector, wherein the functional material array is formed on the surface of the planar metal current collector in advance to obtain a substrate@array precursor electrode, and then a precursor solution capable of forming a solid electrolyte is injected into the functional material array of the substrate@array precursor electrode, followed by in-situ polymerization to obtain the modified self-supporting array current collector.

[0032] In this invention, the array is formed by a template method: the steps are as follows: a porous template with a periodic hole structure is pre-composite on the surface of a planar metal current collector, then the one-dimensional functional material is formed in the periodic hole structure of the porous template, and then the template is etched to form the array.

[0033] Alternatively, the array can be formed by any one of the following methods: hydrothermal method, solvothermal method, photolithography-etching method, vapor deposition method, or micro / nano printing method;

[0034] Specifically:

[0035] When using hydrothermal or solvothermal methods, the steps are as follows: a seed layer of functional material is pre-deposited on the surface of the metal current collector, and then placed in a solution containing a functional material precursor. By controlling the reaction temperature, concentration and time, the one-dimensional array is formed in situ and directionally grown on the surface of the current collector.

[0036] When using the photolithography-etching method, the steps are as follows: a continuous thin film of functional material is pre-deposited or coated on the surface of the metal current collector, then the mask pattern is exposed by photolithography or electron beam exposure, and then the unmasked area is removed by dry etching or wet etching, while the masked area is retained to form the one-dimensional array.

[0037] When using vapor deposition, the steps are as follows: using physical vapor deposition, pulsed laser deposition, or chemical vapor deposition techniques, the one-dimensional array is directly and directionally grown on the surface of the metal current collector by controlling the airflow distribution or the substrate deposition angle.

[0038] When using micro-nano printing, the steps are as follows: ink containing ferroelectric material precursors is directly printed onto the surface of a metal current collector according to a preset array pattern using electrohydrodynamic printing or 3D direct writing printing technology, and then cured by heat treatment.

[0039] Further, when the one-dimensional array is prepared as a doped array, the steps are as follows: when preparing the precursor solution, target material, thin film or ink of the above-mentioned functional material, a compound containing a specific dopant element is added as a dopant source. The dopant element includes at least one of lanthanum (La), strontium (Sr), calcium (Ca), niobium (Nb), tantalum (Ta), zirconium (Zr), iron (Fe), manganese (Mn), cobalt (Co), magnesium (Mg), aluminum (Al), yttrium (Y), neodymium (Nd) or cerium (Ce), and the molar ratio of the dopant element to the functional material is controlled to be 0.5%~8%. Subsequently, during or after the forming process, heat treatment or reaction is carried out at a temperature of 200℃~800℃ (more preferably 650~750℃) for 2~24 hours, more preferably 3~5 hours, so that the dopant element enters the lattice or interstices of the functional material, thereby forming a doped modified array.

[0040] When preparing the one-dimensional array as a modified array, the steps are as follows: after forming a one-dimensional array on the surface of a metal current collector, it is immersed in a solution containing a modifier for surface chemical coating or grafting. The modifier includes at least one of silane coupling agent and titanate coupling agent; the reaction temperature is controlled at 20℃~150℃, the reaction time is 1~12 hours, and after washing and drying, the content of the modifier coated on the surface of the ferroelectric material is 1 wt.%~6 wt.%, thereby forming a modified array coated with the modifier.

[0041] When the one-dimensional array is prepared as a pore array, the steps are as follows: when preparing the precursor solution or ink of the above-mentioned functional material, an appropriate amount of pore-forming agent or micro / nano template is added; after forming an array structure on the surface of the current collector, the pore-forming agent is removed by high-temperature calcination (holding time 1 to 10 hours) in air or an inert atmosphere at 300℃ to 900℃ (more preferably 650 to 750℃), or the template is removed by etching with a chemical solvent, thereby leaving a pore structure on the surface and / or in the bulk phase of the one-dimensional functional material. The pore structure includes at least one of micropores and mesopores, and the porosity is controlled to be 5% to 60% (preferably 10% to 40%), thereby forming a pore array.

[0042] Preferably, the precursor solution is a solution containing monomer, crosslinking agent, initiator, and conductive alkali metal salt;

[0043] Preferably, the monomer includes at least one of cyclic ether monomers, carbonate monomers, and nitrile monomers, and more preferably includes, but is not limited to, at least one of dioxolane (DOL), ethylene oxide derivatives, and polyethylene glycol methacrylate (PEGMA);

[0044] Preferably, the crosslinking agent is selected from at least one of polyfunctional acrylates, polyfunctional methacrylates, or polyfunctional epoxy compounds, including but not limited to at least one of pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polyethylene glycol diglycidyl ether, or glyceryl diglycidyl ether.

[0045] Preferably, the initiator is selected from at least one of photoinitiators, thermal initiators, or Lewis acid initiators, including but not limited to at least one of benzophenone initiators, phosphate initiators, or borofluorophosphate compounds; for example, the initiator may be lithium difluorooxalate borate (LiDFOB).

[0046] Preferably, the precursor solution may also contain a solvent, including cyclic ether solvents, carbonate solvents, ether solvents or combinations thereof, preferably including but not limited to at least one of dioxolane, ethylene carbonate, propylene carbonate, dimethyl carbonate or ethylene glycol dimethyl ether; furthermore, the monomer may also be used as a solvent.

[0047] Preferably, the in-situ polymerization temperature is 20~120 ℃, more preferably 25~80 ℃, and further preferably 40~70 ℃; the in-situ polymerization time can be more than 5 hours, and further preferably 20~60 hours.

[0048] Preferably, the material is pretreated under negative pressure before in-situ polymerization.

[0049] The present invention also provides an application of the modified self-supporting array current collector described above, which is combined with the positive electrode to prepare a negative electrode-free battery; wherein the solid electrolyte side of the modified self-supporting array current collector is arranged opposite to the positive electrode.

[0050] In this invention, the negative electrode-free battery can be a negative electrode-free lithium battery, wherein the conductive salt of the polymer electrolyte is a conductive lithium salt. Alternatively, the negative electrode-free battery can be a negative electrode-free sodium battery, wherein the conductive salt of the polymer electrolyte is a conductive sodium salt. Or, the negative electrode-free battery can be a negative electrode-free potassium battery, wherein the conductive salt of the polymer electrolyte is a conductive potassium salt.

[0051] The present invention also provides a negative electrode-free battery, including a positive electrode and the modified self-supporting array current collector, wherein the solid electrolyte side of the modified self-supporting array current collector is disposed opposite to the positive electrode;

[0052] Preferably, the electrodeless battery is an electrodeless lithium metal battery, an electrodeless sodium metal battery, or an electrodeless potassium metal battery.

[0053] Beneficial effects

[0054] 1. Improved interfacial stability and reduced impedance of electrodeless batteries: By constructing a special z-axis array ferroelectric structure in situ on the current collector surface and performing in-situ infiltration and solidification of the polymer electrolyte, a deep-intercalated continuous interface is formed. This structure effectively buffers the volume expansion stress during the severe deposition / stripping of electrodeless batteries, avoids interfacial debonding during cycling, and significantly reduces interfacial charge transfer impedance.

[0055] 2. Synergistic Guidance for Uniform Deposition, Suppressing Dendrite and "Dead Metal" Formation: This invention utilizes the physical confinement of the z-axis (height direction) array to provide ample space for alkali metals, and relies on the spontaneous polarization characteristics of ferroelectric materials to construct a directional built-in electric field within the channels. The synergistic effect of these two factors actively homogenizes the ion flux under high local current density, guiding the uniform nucleation and growth of alkali metals within the array, thereby significantly suppressing dendrite penetration and the formation of "dead lithium / dead sodium".

[0056] 3. Simplify the internal battery structure and improve overall energy density: By constructing an ultra-thin integrated structure of negative electrode current collector / polarization array / electrolyte, the use of separate separators and thicker electrolyte layers is reduced. This design reduces the mass and volume ratio of inactive materials, fully releasing the high specific energy potential of negative electrode-free batteries under a minimalist architecture.

[0057] 4. Excellent process compatibility and versatility: The array fabrication and in-situ polymerization technology of this invention is compatible with conventional micro-nano fabrication and solution processing techniques. The structural parameters (morphology, porosity) and ferroelectric material composition are highly tunable, making it widely applicable to various lithium, sodium, potassium, and other electrodeless secondary batteries and multiple polymer electrolyte systems, demonstrating potential for large-scale application. Attached Figure Description

[0058] Figure 1 This is a structural diagram of the current collector in the negative electrode-free battery of Example 1; Detailed Implementation

[0059] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0060] In the following embodiments, the full-cell tests all use a negative electrode-free battery system, that is: when assembling the full cell, no metal lithium foil or active negative electrode powder material is added to the negative electrode side in advance; all active lithium ions participating in the cycle in the battery come from the extraction of positive electrode material during the first charge.

[0061] The array-type ferroelectric structure is formed in situ on the surface of the current collector and can be doped with elements, surface controlled, or modified at the interface as needed to improve its electrical properties and interface stability. The integrated negative electrode / electrolyte structure of this invention achieves synergy between structure and function by liquid-phase infiltration and in-situ polymerization of the polymer electrolyte in the presence of the array structure, allowing the polymer electrolyte to fully fill the array channels and form a stable intercalation with the array structure.

[0062] The specific performance testing method includes the following steps:

[0063] (1) Impedance test: The prepared integrated negative electrode / electrolyte electrode sheet was sandwiched between two stainless steel sheets in an inert atmosphere glove box to assemble a CR2025 button cell. The cell was tested using AC impedance spectroscopy (EIS) on a Gamry electrochemical workstation to characterize the ion transport properties of the integrated structure.

[0064] (2) Electrochemical stability window test: The prepared integrated negative electrode / electrolyte structure electrode sheet was sandwiched between a stainless steel sheet and a commercial lithium sheet in an inert atmosphere glove box to assemble a CR2025 coin cell. The cell was tested using linear sweep voltammetry (LSV) in a Gamry electrochemical workstation to evaluate the electrochemical stability window of the electrolyte in the integrated structure.

[0065] (3) Ion transport number test: In an inert atmosphere glove box, the prepared integrated negative electrode / electrolyte structure electrode sheet was sandwiched between two commercial lithium sheets to assemble a CR2025 coin cell. The battery was tested using AC impedance spectroscopy (EIS) combined with DC polarization (potentiostatic) method in a Gamry electrochemical workstation to obtain the current change curve under constant potential conditions and the impedance change before and after polarization, thereby calculating the ion transport number.

[0066] Example 1

[0067] A self-supporting array-type ferroelectric material-based integrated anode / electrolyte structure and its preparation method.

[0068] The ferroelectric material is niobium (Nb)-doped barium titanate (BaTiO3), with a molar content of 4 mol% for the doping element; the polymer monomer is 1,3-dioxolane (DOL); the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); the initiator is lithium difluorooxalate borate (LiDFOB); and the crosslinking agent is trimethylolpropane triglycidyl ether (TTE).

[0069] The preparation method of the integrated negative electrode / electrolyte electrode sheet includes the following steps:

[0070] (1) Using copper foil as the metal current collector substrate, a template layer and a ferroelectric material precursor layer are sequentially constructed on its surface. Specifically, a porous alumina (AAO) film with a regular pore structure is selected as the array template. The AAO template is a template with an ordered regular square grid of holes (the square grid holes are straight, parallel, and non-intersecting columnar nanopores, wherein the pore direction is perpendicular and penetrates the template surface); the pore diameter is about 300 nm, the pore depth (i.e., the array height) is 10 μm, and the spacing between adjacent holes is about 200 nm, which is then used to cover the surface of the copper foil.

[0071] Subsequently, a sol precursor solution for ferroelectric materials was prepared: titanium source (tetraethyl titanate), barium source (barium nitrate), and niobium source (niobium nitrate) were dissolved in a mixed solvent of anhydrous ethanol and deionized water according to stoichiometric ratio, and citric acid was added as a complexing agent (controlling the molar ratio of citric acid to total metal ions to be 1.5:1). The solution was stirred at a constant temperature of 60 ℃ for 2 hours to form a uniform and transparent sol precursor solution, wherein the amount of niobium source added corresponds to a niobium doping molar content of 4 mol in the ferroelectric material.

[0072] The sol precursor solution was introduced into the AAO template channels by vacuum-assisted permeation. After fully filling the template channels, it was dried in an 80 °C oven for 12 h to allow the sol to gel. Subsequently, it was transferred to a muffle furnace and heated to 700 °C at a heating rate of 2 °C / min in air atmosphere and held for 4 h to convert it into a barium titanate-based ferroelectric phase. This resulted in the in-situ formation of a vertically oriented niobium-doped barium titanate array structure with through-channels on the copper foil surface.

[0073] Subsequently, the AAO template was removed, and the structure with the template was immersed in a 3 mol / L sodium hydroxide (NaOH) solution. The structure was etched at room temperature for 4 h to completely dissolve and remove the AAO template. After repeated washing with deionized water and anhydrous ethanol and vacuum drying, a self-supporting niobium-doped barium titanate array structure was obtained.

[0074] (2) Preparation of polymer electrolyte precursor solution: Using DOL as polymer monomer, add LiTFSI to make the lithium salt concentration 1.0 mol / L, then add LiDFOB as initiator (concentration in precursor solution is 0.2 mol / L) and TTE as crosslinking agent (accounting for 2 wt% of monomer mass), and stir at room temperature until the system is homogeneous.

[0075] (3) The polymer electrolyte precursor solution obtained in step (2) is introduced into the niobium-doped barium titanate array structure obtained in step (1) so that the precursor solution fully wets the array channels and its surface under normal pressure (the surface is just covered). Then, in-situ polymerization and curing are carried out at 50 °C for 48 h, so that the polymer electrolyte is formed in-situ in the array channels, and finally a self-supporting array-type ferroelectric material-based anode / electrolyte integrated structure electrode sheet is obtained.

[0076] Assembly and electrochemical performance testing of electrodeless batteries:

[0077] Assembly conditions: In a high-purity glove box filled with argon, the integrated negative electrode / electrolyte structure electrode sheet prepared in Example 1 was used as the negative electrode side (without pre-placed active lithium metal), and a commercial lithium iron phosphate (LiFePO4) electrode sheet was used as the positive electrode (including aluminum foil and positive electrode materials composited on its surface, the positive electrode sub-materials including LFP, PVDF and conductive carbon black in a weight ratio of 8:1:1). The CR2032 type negative electrode-free coin cell (relying on the in-situ polymer electrolyte in the integrated structure to conduct ions) was directly assembled.

[0078] Test conditions and results:

[0079] ① Basic electrochemical performance testing: The electrochemical impedance spectroscopy was used for testing. The ionic conductivity of the integrated structure prepared in Example 1 at room temperature was 1.0 × 10⁻⁶. -4 S cm -1 The electrochemical stability window reached 4.6 V (vs. Li / Li) when measured by linear sweep voltammetry. + The lithium-ion transference number was approximately 0.55, as measured using a method combining DC polarization and AC impedance.

[0080] ② Cycle performance test of the electrodeless battery: At 25 ℃, the charge / discharge voltage range was set to 2.5 V ~ 4.0 V, and constant current charge / discharge tests were conducted at a rate of 0.5 C. The results show that, due to the strong physical confinement and polarization induction effect of the ferroelectric array, the electrodeless battery still retains more than 88.5% of its capacity after 100 charge / discharge cycles. No obvious dendrite puncture was found during battery disassembly after the test.

[0081] Example 2

[0082] Compared with Example 1, the only difference is that the ferroelectric material used is different, and niobium-doped barium titanate is replaced by niobium (Nb)-doped bismuth ferrite (BiFeO3). All other operations and parameters are the same as in Example 1.

[0083] Specifically, in this embodiment, when preparing the ferroelectric material sol precursor solution, the metal sources used are bismuth source (bismuth nitrate), iron source (ferric nitrate), and niobium source (niobium nitrate), wherein the molar content of niobium doping is still 3 mol%. The resulting self-supporting array structure is a niobium-doped bismuth ferrite array structure.

[0084] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0085] Example 3

[0086] Compared with Example 1, the only difference is that the ferroelectric material used is different, and niobium-doped barium titanate is replaced by barium titanate-zirconium barium titanate ferroelectric solid solution (which can be represented as BaTi). 1-x Zr x O3, where x is 0.5). Other operations and parameters are the same as in Example 1.

[0087] Specifically, in this embodiment, when preparing the ferroelectric material sol precursor solution, the metal sources used are barium (barium nitrate), titanium (tetraethyl titanate), and zirconium (zirconium nitrate). No niobium doping source was introduced. A solid solution structure was formed by adjusting the molar ratio of the titanium and zirconium sources. The resulting self-supporting array structure is a barium titanate–zirconate barium titanate ferroelectric solid solution array structure.

[0088] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0089] Example 4

[0090] Compared to Example 1, the only difference is that the ferroelectric material is not doped (i.e., undoped barium titanate, BaTiO3 is used). All other operations and parameters are the same as in Example 1.

[0091] Specifically, in this embodiment, when preparing the ferroelectric material sol precursor solution, the solution contains only titanium and barium sources, without introducing any doping elements. The resulting self-supporting array structure is an undoped barium titanate array structure.

[0092] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0093] Example 5

[0094] Compared with Example 1, the only difference is that in step (1), a pore-forming agent was added when preparing the ferroelectric material sol precursor solution, thereby introducing a mesoporous structure into the array. Other operations, material parameters (niobium-doped barium titanate), and polymer electrolyte composition are the same as in Example 1.

[0095] Specifically, in the preparation method of the integrated negative electrode / electrolyte structure electrode sheet in this embodiment:

[0096] In step (1), when preparing the niobium-doped barium titanate sol precursor solution, a block copolymer (Pluronic F127) was added to the solution as a pore-forming agent (5% of the total metal source weight). The precursor solution containing the pore-forming agent was introduced into the AAO template and then subjected to controlled drying and high-temperature heat treatment. During the heat treatment, the block copolymer decomposed and volatilized upon heating, generating a large number of mesoporous structures with a size of 10–30 nm (porosity approximately 25%) in situ on both the bulk and surface of the niobium-doped barium titanate ferroelectric phase. Subsequently, the AAO template was removed, yielding a self-supporting porous niobium-doped barium titanate array structure.

[0097] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0098] Example 6

[0099] Compared with Example 1, the only difference is that after step (1), the obtained ferroelectric array was modified by surface lithiumophilic coating. Other operations, material parameters (niobium-doped barium titanate) and polymer electrolyte composition are the same as in Example 1.

[0100] Specifically, in the preparation method of the integrated negative electrode / electrolyte structure electrode sheet in this embodiment: after completely dissolving and removing the AAO template in step (1) and obtaining a self-supporting niobium-doped barium titanate array structure, a surface modification step is added: using atomic layer deposition (ALD) technology, a zinc oxide (ZnO) nanoparticle coating layer with a thickness of about 5 nm is uniformly deposited on the surface of the above array framework, thereby obtaining a modified array coated with ZnO. Subsequent steps (2) and (3) are the same as in Example 1.

[0101] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0102] Example 7

[0103] Compared with Example 1, the only difference is that in step (3), a negative pressure in-situ permeation scheme was used when introducing the polymer electrolyte precursor solution. The other preliminary array preparation steps, material parameters (niobium-doped barium titanate), and polymer electrolyte composition are the same as in Example 1.

[0104] Specifically, in the preparation method of the integrated negative electrode / electrolyte structure electrode sheet in this embodiment:

[0105] Step (3) is changed to: uniformly drop the electrolyte precursor solution obtained in step (2) onto the surface of the niobium-doped barium titanate array obtained in step (1), and then quickly place it in a vacuum chamber, evacuate it to a negative pressure state with an absolute pressure of 10 kPa ~ 20 kPa (or a gauge pressure of about -0.08 MPa ~ -0.09 MPa), and maintain the pressure for 2~5 min to extract the microbubbles inside the channels; then slowly restore it to normal pressure. During the restoration of normal pressure, under the dual drive of atmospheric pressure difference and capillary force, the precursor liquid is deeply pressed into the micron-level array gaps (this operation of evacuating negative pressure and restoring normal pressure can be repeated 2~3 times to ensure no dead-angle wetting); finally, in-situ polymerization and curing is carried out at 50 ℃ for 48 h, so that the polymer electrolyte is formed in-situ in the array channels, forming a deeper mechanical bonding interface.

[0106] The test was conducted using the method described in Example 1, and the results are shown in Table 1.

[0107]

[0108] As demonstrated in Examples 1-4, forming the Z-axis array described in this invention, combined with the in-situ preparation method, can yield superior performance. Furthermore, as demonstrated in Examples 1, 5, and 6, constructing a porous structure or forming a modified layer within the array can achieve even better electrochemical performance. As demonstrated in Examples 1 and 7, coating with a precursor solution followed by negative pressure treatment, and then coating again, can yield superior electrochemical performance.

[0109] Comparative Example 1

[0110] This comparative example, based on Example 1, uses a conventional physical coating method to prepare the negative electrode interface. Specifically, niobium-doped barium titanate (Nb-BaTiO3) one-dimensional nanowires with the same composition as in Example 1, polyvinylidene fluoride (PVDF) binder, and conductive carbon black are mixed to form a slurry, which is then coated onto the surface of a copper foil current collector. After drying, a randomly distributed, non-self-supporting one-dimensional ferroelectric composite coating (i.e., the vertically arrayed pore structure is lost) is formed on the copper foil surface. Subsequently, the same electrolyte precursor solution as in Example 1 is dropped onto the coating surface and in-situ polymerization is carried out. All other components and steps remain unchanged, and an integrated negative electrode / electrolyte structure and a negative electrode-less battery are assembled.

[0111] Using the exact same test conditions as in Example 1, the tests showed that the ionic conductivity of this integrated structure at room temperature is 8 × 10⁻⁶. -5 S cm -1 The lithium-ion transference number is only 0.42. The capacity retention of the electrodeless full cell after 100 cycles is 45.2%, and the average coulombic efficiency is only 96.50%.

[0112] Comparative Example 2

[0113] Based on Example 1, this comparative example uses a traditional non-in-situ coating method to form the electrolyte interface, without employing an in-situ polymerization liquid phase infiltration process.

[0114] Specifically, after constructing the same niobium-doped barium titanate array structure as in Example 1 on the surface of the copper foil current collector, a viscous adhesive solution formed by mixing pre-synthesized polyethylene oxide (PEO), lithium salt, and solvent was cast and coated onto the array surface and then dried and cured. Other components and assembly steps remained unchanged, thus preparing an integrated negative electrode / electrolyte structure and a negative electrode-free battery.

[0115] Using the exact same test conditions as in Example 1, the tests showed that the ionic conductivity of this integrated structure at room temperature is 1.5 × 10⁻⁶. -5 S cm -1 The lithium-ion transference number is only 0.35. The capacity retention of the electrodeless full cell after 100 cycles is 25.5%, and the average coulombic efficiency is only 92.10%.

[0116] Comparative Example 3

[0117] This comparative example differs from Example 1 in that the array structure does not use ferroelectric materials, but instead uses conventional non-ferroelectric materials (i.e., porous alumina arrays). Other components (polymer electrolyte) and assembly steps remain unchanged.

[0118] Specifically, to prepare a non-ferroelectric alumina (Al2O3) array with structural parameters similar to those in Example 1: a copper foil was used as the metal current collector substrate, and a pyrolytic polycarbonate (PC) microporous membrane with the same regular pore structure was selected as the array template and covered on the surface (this replaced the AAO template to avoid subsequent etching solvent conflicts); then, an aluminum source (such as aluminum nitrate) sol precursor solution was prepared and introduced into the template pores. After it was fully filled, it was dried under controlled conditions and then calcined at 600 °C in air atmosphere. During the calcination process, the PC template was completely pyrolyzed and vaporized, and the sol was transformed into the alumina phase, thereby forming a non-ferroelectric porous alumina (Al2O3) array in situ on the copper foil surface. Subsequently, an electrolyte precursor solution exactly the same as that in Example 1 was introduced into the array and in-situ polymerized and cured at 50 °C.

[0119] The integrated structure has an ionic conductivity of 9 × 10⁻⁶ at room temperature. -5 S cm -1 The lithium-ion transference number is only 0.38. At room temperature, the assembled electrodeless battery retains 62.3% of its capacity after 100 cycles, with an average coulombic efficiency of 98.15%.

[0120] Comparative Example 4

[0121] This comparative example, based on Example 1, does not employ any array-confined framework structure, but only uses a pure in-situ polymer electrolyte.

[0122] Specifically, the steps of preparing the ferroelectric material array using the template method in Example 1 were omitted. Instead, the same polymer electrolyte precursor solution as in Example 1 was directly dropped onto the surface of the bare copper foil current collector, followed by in-situ polymerization and curing at 50 °C. Other components and assembly steps remained unchanged, and a pure polymer electrolyte coating and a negative electrode-free battery were prepared.

[0123] The integrated structure has an ionic conductivity of 9.5 × 10⁻⁶ at room temperature. -5 S cm -1 The lithium-ion transference number is only 0.32. At room temperature, the assembled electrodeless battery retains 18.6% of its capacity after 100 cycles, with an average coulombic efficiency of 90.20%.

[0124] Comparative Example 5

[0125] Compared with Example 1, the only difference is that the one-dimensional ferroelectric material of Example 1 is dispersed in the precursor solution of Example 1, mixed and coated on copper foil for polymerization. All other operations and parameters are the same as in Example 1.

[0126] The integrated structure has an ionic conductivity of 1.05 × 10⁻⁶ at room temperature. -4 S cm -1 The lithium-ion transference number is only 0.44. At room temperature, the assembled electrodeless battery retains 54.5% of its capacity after 100 cycles, with an average coulombic efficiency of 97.25%.

Claims

1. A modified self-supporting array current collector, characterized in that, This includes planar metal current collectors, functional material arrays composited on the surface of planar metal current collectors, and polymer electrolytes in situ composited in the gaps and surfaces of functional material arrays; The functional material array includes one-dimensional functional materials arranged in an array along the height direction of the planar metal current collector; The functional material is a ferroelectric material.

2. The modified self-supporting array current collector as described in claim 1, characterized in that, Planar metal current collectors include metal current collectors, whose materials include, but are not limited to, at least one of copper, nickel, and stainless steel.

3. The modified self-supporting array current collector as described in claim 1, characterized in that, The ferroelectric material includes at least one of barium titanate, lead zirconate titanate, strontium titanate, sodium bismuth titanate, potassium bismuth titanate, strontium bismuth titanate, calcium bismuth titanate, lanthanum bismuth titanate, iron bismuth titanate, barium zirconate titanate, strontium zirconate titanate, bismuth titanate, lithium niobate, sodium niobate, lithium tantalate, sodium tantalate, bismuth ferrite, bismuth titanite, and bismuth manganese ferrite.

4. The modified self-supporting array current collector as described in claim 3, characterized in that, The functional material is a doped and modified ferroelectric material; and / or a ferroelectric material coated with a modifier; The doped ferroelectric material includes at least one doping element selected from lanthanum (La), strontium (Sr), calcium (Ca), niobium (Nb), tantalum (Ta), zirconium (Zr), iron (Fe), manganese (Mn), cobalt (Co), magnesium (Mg), aluminum (Al), yttrium (Y), neodymium (Nd), or cerium (Ce), and the content of the doping element is 0.5~8 mol% In the ferroelectric material coated with a modifier, the modifier includes at least one of silane coupling agent, titanate coupling agent, and transition metal oxide; and the content of the modifier is 1~6 wt.%; or, the thickness of the modifier is ≤10 nm; further, it can be 2~8 nm.

5. The modified self-supporting array current collector as described in claim 1, characterized in that, The cross-section of the one-dimensional functional material is at least one of a cube, cuboid, cylinder, and hexagon; Preferably, in the array, the planar size of the one-dimensional functional material is 10 nm to 100 μm, more preferably 200 nm to 5 μm, and the array height is 0.5 to 100 μm, more preferably 2 to 30 μm; the spacing between the one-dimensional functional materials is 10 nm to 50 μm, more preferably 100 nm to 10 μm. Preferably, the surface and / or bulk phase of the one-dimensional functional material further includes a pore structure of at least one of micropores and mesopores, and the porosity is 5-60%, preferably 10-40%.

6. The modified self-supporting array current collector as described in claim 1, characterized in that, Polymer electrolytes are obtained by in-situ polymerization of a solution containing monomers, crosslinking agents, initiators, and conductive alkali metal salts.

7. A method for preparing the modified self-supporting array current collector according to any one of claims 1 to 6, characterized in that, The functional material array is pre-formed on the surface of the planar metal current collector to obtain a substrate@array precursor electrode. Then, a precursor solution capable of forming a solid electrolyte is injected into the functional material array of the substrate@array precursor electrode, followed by in-situ polymerization to obtain the modified self-supporting array current collector.

8. The method for preparing the modified self-supporting array current collector as described in claim 7, characterized in that, The array is formed using the template method, and its steps are as follows: A porous template with a periodic hole structure is pre-coated on the surface of a planar metal current collector. Then, the one-dimensional functional material is formed within the periodic hole structure of the porous template. The template is then etched to form the array. Alternatively, the array can be formed by any one of the following methods: hydrothermal method, solvothermal method, photolithography-etching method, vapor deposition method, or micro / nano printing method; Preferably, the precursor solution is a solution containing monomer, crosslinking agent, initiator, and conductive alkali metal salt; Preferably, the monomer includes at least one of cyclic ether monomers, carbonate monomers, and nitrile monomers, and more preferably includes, but is not limited to, at least one of dioxolane (DOL), ethylene oxide derivatives, and polyethylene glycol methacrylate (PEGMA); Preferably, the crosslinking agent is selected from at least one of polyfunctional acrylates, polyfunctional methacrylates, or polyfunctional epoxy compounds, including but not limited to at least one of pentaerythritol tetraacrylate, trimethylolpropane triacrylate, polyethylene glycol diglycidyl ether, or glyceryl diglycidyl ether. Preferably, the initiator is selected from at least one of photoinitiators, thermal initiators, or Lewis acid initiators, including but not limited to at least one of benzophenone initiators, phosphate initiators, or borofluorophosphate compounds; Preferably, the precursor solution further comprises a solvent, which includes cyclic ether solvents, carbonate solvents, ether solvents or combinations thereof, preferably including but not limited to at least one of dioxolane, ethylene carbonate, propylene carbonate, dimethyl carbonate or ethylene glycol dimethyl ether; Preferably, the in-situ polymerization temperature is 20~120 ℃, more preferably 25~80 ℃; Preferably, the material is pretreated under negative pressure before in-situ polymerization.

9. The application of the modified self-supporting array current collector according to any one of claims 1 to 6 or the modified self-supporting array current collector prepared by the preparation method according to any one of claims 7 to 8, characterized in that, The modified self-supporting array current collector is combined with the positive electrode to prepare a negative electrode-free battery; wherein the solid electrolyte side of the modified self-supporting array current collector is arranged opposite to the positive electrode.

10. A negative electrode-free battery, characterized in that, The device includes a positive electrode and a modified self-supporting array current collector as described in any one of claims 1 to 6 or a modified self-supporting array current collector prepared by any one of claims 7 to 8; wherein the solid electrolyte side of the modified self-supporting array current collector is disposed opposite to the positive electrode. Preferably, the electrodeless battery is an electrodeless lithium metal battery, an electrodeless sodium metal battery, or an electrodeless potassium metal battery.

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