Oriented structure negative electrode and preparation method thereof, and electrochemical device

Abstract

The application discloses a directional structure anode-free electrode, a preparation method thereof and an electrochemical device. The directional structure anode-free electrode comprises a current collector, a composite interface layer covering at least one side surface of the current collector, and the composite interface layer comprises a lithium-containing inorganic interface layer arranged on at least one side surface of the current collector and an organic interface layer arranged on the side of the lithium-containing inorganic interface layer away from the current collector. The organic interface layer is provided with a plurality of concave parts in a dispersed or continuous mode, and the concave parts extend from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer. The lithium-containing inorganic interface layer can accelerate the transport of lithium ions in the direction parallel to the surface of the electrode, improve the nucleation and growth behavior of lithium, promote the formation of regular pile-shaped lithium deposition, and improve the environment of the lithium deposition interface. The concave parts can limit the morphology of lithium growth, effectively ensure the uniform growth of lithium in the concave parts, guarantee the interface stability of the anode electrode, and prolong the cycle life of the anode-free battery.

Description

Technical Field

[0001] This application belongs to the field of negative electrode technology, and particularly relates to a directional structure negative electrode, its preparation method, and an electrochemical device. Background Technology

[0002] Lithium-ion batteries have been widely used in various fields such as consumer electronics, electric vehicles, large-scale energy storage, and drones due to their numerous advantages, including high operating voltage, high specific energy, long cycle life, low self-discharge rate, and no memory effect. However, the theoretical specific capacity of the negative electrode is relatively low (for example, graphite has a theoretical specific capacity of 372 mAh·cm³). -2 This limits the further improvement of the energy density of lithium-ion batteries. Electrodeless batteries combine the high theoretical specific capacity and low redox potential of lithium metal batteries. Furthermore, because the negative electrode only contains a current collector, electrodeless batteries have significant advantages in both mass energy density and volumetric energy density. In actual battery manufacturing, electrodeless batteries eliminate conventional electrode preparation steps such as coating and rolling on the negative electrode side, and since no metallic lithium is involved, they have high compatibility with existing lithium-ion battery assembly equipment, ensuring strong safety.

[0003] However, electrodeless batteries still face significant challenges during cycling. Low cycle life is a key factor limiting their application. After the initial charge and discharge, electrodeless batteries operate as lithium metal batteries, and their cycle life is limited by the coulombic efficiency and deposition morphology of lithium metal. Negative electrode dendritic deposition not only consumes a large amount of electrolyte, but incomplete removal also leads to the continuous accumulation of inactive lithium at the interface between the negative electrode current collector and the electrolyte, resulting in increasing electrode polarization and reduced cycle life during cycling. Summary of the Invention

[0004] This application provides a directional structure electrode without a negative electrode, which can improve the lithium deposition interface environment, regulate the lithium deposition morphology, and effectively extend the cycle life of the electrodeless battery.

[0005] In a first aspect, this application provides a directional structure negative electrode, comprising: a current collector; and a composite interface layer covering at least one surface of the current collector; the composite interface layer comprising: a lithium-containing inorganic interface layer disposed at least on one surface of the current collector; and an organic interface layer disposed on the side of the lithium-containing inorganic interface layer away from the current collector, wherein the organic interface layer has a plurality of recesses disposed dispersedly or continuously, and the recesses extend from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer.

[0006] According to an embodiment of the first aspect of this application, the current collector is a copper current collector.

[0007] According to an embodiment of the first aspect of this application, the copper current collector is selected from at least one of smooth copper foil, matte copper foil, mesh copper foil, foamed copper foil, and polymer composite copper foil.

[0008] According to an embodiment of the first aspect of this application, the lithium-containing inorganic interface layer includes one or more lithium-containing inorganic materials selected from lithium fluoride, lithium oxide, lithium nitride, lithium carbonate, and lithium nitrate.

[0009] According to an embodiment of the first aspect of this application, the thickness of the lithium-containing inorganic interface layer is 1 nm to 100 nm.

[0010] According to an embodiment of the first aspect of this application, the material of the organic interface layer is selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyacrylonitrile, or a combination thereof.

[0011] According to an embodiment of the first aspect of this application, the thickness of the organic interface layer is 400 nm to 1000 nm.

[0012] According to an embodiment of the first aspect of this application, the recesses are arranged in an array within a first predetermined region of the organic interface layer.

[0013] According to an embodiment of the first aspect of this application, the cross-section of the concave portion along the thickness direction of the organic interface layer is T-shaped, I-shaped, Y-shaped, C-shaped, U-shaped, O-shaped, H-shaped, or cross-shaped.

[0014] According to an embodiment of the first aspect of this application, the recess is an oriented hole extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer.

[0015] According to an embodiment of the first aspect of this application, the aperture of the directional aperture is 50 nm to 500 nm.

[0016] According to an embodiment of the first aspect of this application, the spacing of the directional apertures is 10 nm to 2000 nm.

[0017] According to an embodiment of the first aspect of this application, the aperture d of the directional hole and the depth h of the directional hole satisfy: d / h = 0.05~1.

[0018] According to an embodiment of the first aspect of this application, the directional holes are arranged in an array.

[0019] According to an embodiment of the first aspect of this application, the shape of the cross-section of the directional hole along the thickness direction of the organic interface layer is circular, elliptical, triangular, square, or a regular polygon with more than five sides.

[0020] According to an embodiment of the first aspect of this application, from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer, the pore size of the directional holes is gradually reduced from large to small.

[0021] Secondly, this application provides a method for preparing a directional structure electrode without a negative electrode, comprising: providing a current collector; depositing a lithium-containing inorganic material on at least one side surface of the current collector by vacuum thermal evaporation or atomic layer deposition to form a lithium-containing inorganic interface layer; forming an organic interface layer on the side of the lithium-containing inorganic interface layer away from the current collector, and forming a concave portion on the organic interface layer extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the inner portion of the lithium-containing inorganic interface layer; and forming a composite interface layer by the lithium-containing inorganic interface layer and the organic interface layer.

[0022] According to an embodiment of the second aspect of this application, providing a current collector includes: soaking the current collector in a cleaning solution; rinsing the soaked current collector with anhydrous ethanol; and drying the rinsed current collector to remove the anhydrous ethanol and dry the surface of the current collector.

[0023] According to an embodiment of the second aspect of this application, the cleaning solution is acetone. The current collector after rinsing can be dried in an environment of 75°C to 90°C.

[0024] According to an embodiment of the second aspect of this application, forming an organic interface layer on the side of the lithium-containing inorganic interface layer away from the current collector includes: preparing a precursor treatment solution using an organic material and a first organic solvent; coating the precursor treatment solution onto the surface of the lithium-containing inorganic interface layer away from the current collector to form a first electrode containing a precursor coating; drying the first electrode at 30°C to 60°C for 2 to 4 hours to obtain a first electrode containing an organic interface layer; and drying the first electrode containing the organic interface layer at 40°C to 60°C for 12 to 36 hours to obtain a directional structure negative electrode containing an organic interface layer.

[0025] According to an embodiment of the second aspect of this application, forming an organic interface layer on the side of the lithium-containing inorganic interface layer away from the current collector includes: preparing a precursor treatment solution using an organic material and a first organic solvent; covering the surface of the lithium-containing inorganic interface layer away from the current collector with a mask; coating the precursor treatment solution onto the mask in a drying chamber to form a first electrode containing a precursor coating; drying the first electrode at 30°C to 60°C for 2 to 4 hours to obtain a first electrode containing an organic interface layer; drying the first electrode containing the organic interface layer at 40°C to 60°C for 12 to 36 hours; and removing the mask with a second organic solvent to obtain a oriented structure negative electrode containing an organic interface layer.

[0026] According to an embodiment of the second aspect of this application, the first organic solvent is one or a combination of several of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and acetonitrile (AN).

[0027] According to an embodiment of the second aspect of this application, an organic material and a first organic solvent are formulated into a precursor treatment solution at a mass ratio of (1-10):(1-10).

[0028] Thirdly, this application provides an electrochemical device comprising: the above-described oriented structure without a negative electrode.

[0029] The directional electrode structure without a negative electrode of this application includes a current collector and a composite interface layer covering at least one side of the current collector. The composite interface layer includes a lithium-containing inorganic interface layer disposed on one side of the current collector and an organic interface layer disposed on the side of the lithium-containing inorganic interface layer away from the current collector. The lithium-containing inorganic interface layer accelerates the transport of lithium ions in the direction parallel to the electrode surface, effectively improving lithium nucleation and growth behavior, promoting the formation of well-ordered stacked lithium deposits, and improving the environment of the lithium deposition interface. Furthermore, multiple portions of the organic interface layer dispersed or continuously disposed on the surface away from the lithium-containing inorganic interface layer and extending to the concave portion of the lithium-containing inorganic interface layer restrict the morphology of lithium growth, effectively ensuring uniform lithium growth within the concave portion, thus guaranteeing the interface stability of the directional electrode structure without a negative electrode and extending the cycle life of the electrodeless battery. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the directional structure without a negative electrode provided in the embodiments of this application.

[0032] Figure 2 This is a cross-sectional thickness diagram of the lithium fluoride inorganic interface layer provided in one embodiment of this application, obtained by atomic force microscopy.

[0033] Figure 3 This is a surface morphology image of the lithium fluoride inorganic interface layer provided in one embodiment of this application, obtained by atomic force microscopy.

[0034] Figure 4 This is a surface morphology image of the organic interface layer on the surface of the composite interface layer provided in one embodiment of this application, obtained by scanning electron microscopy.

[0035] Figure 5 This is a cross-sectional thickness diagram of the lithium nitride inorganic interface layer obtained by atomic force microscopy, provided in another embodiment of this application.

[0036] Figure 6This is a surface morphology image of the lithium nitride inorganic interface layer provided in another embodiment of this application, obtained by atomic force microscopy.

[0037] Figure 7 This is a discharge capacity diagram of the oriented structure negative electrode without electrode prepared in the embodiments and comparative examples of this application after being applied to a lithium metal battery.

[0038] Figure 8 This is a coulombic efficiency diagram of the oriented structure negative electrode without electrode prepared in the embodiments and comparative examples of this application after being applied to lithium metal batteries.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Current collector; 2. Composite interface layer; 201. Lithium-containing inorganic interface layer; 202. Organic interface layer; 2021. Concave portion. Detailed Implementation

[0041] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0043] To address the problems of the prior art, this application provides a directional structure negative electrode, its preparation method, and an electrochemical device. The directional structure negative electrode provided in this application is described below.

[0044] Figure 1 A schematic diagram of the directional structure without a negative electrode provided in an embodiment of this application is shown. Figure 1As shown, the directional structure negative electrode provided in this application includes: a current collector 1; a composite interface layer 2 covering at least one side surface of the current collector 1; the composite interface layer 2 includes: a lithium-containing inorganic interface layer 201, which is disposed at least on one side surface of the current collector 1; an organic interface layer 202, which is disposed on the side of the lithium-containing inorganic interface layer 201 away from the current collector 1, wherein the organic interface layer 202 has a plurality of recesses 2021 disposed dispersedly or continuously, and the recesses 2021 extend from the surface of the organic interface layer 202 away from the lithium-containing inorganic interface layer 202 to the lithium-containing inorganic interface layer 201.

[0045] The directional electrode structure without a negative electrode of this application includes a current collector and a composite interface layer covering at least one side of the current collector. The composite interface layer includes a lithium-containing inorganic interface layer disposed on one side of the current collector and an organic interface layer disposed on the side of the lithium-containing inorganic interface layer opposite to the current collector. The lithium-containing inorganic interface layer accelerates the transport of lithium ions in the direction parallel to the electrode surface, effectively improving lithium nucleation and growth behavior, promoting the formation of well-ordered stacked lithium deposits, and improving the environment of the lithium deposition interface. Furthermore, the multiple recesses dispersed or continuously disposed in the organic interface layer, extending from the surface of the organic interface layer opposite to the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer, restrict the morphology of lithium growth, effectively ensuring uniform lithium growth within the recesses, thus guaranteeing the interface stability of the directional electrode structure without a negative electrode and extending the cycle life of the electrodeless battery.

[0046] In some embodiments of this application, the current collector is a copper current collector.

[0047] In some embodiments of this application, the copper current collector is selected from at least one of smooth copper foil, matte copper foil, mesh copper foil, foamed copper foil, and polymer composite copper foil. For example, the polymer composite copper foil can be PET copper foil, which is a three-layer structure with a PET polymer layer in the middle and copper foil on both sides.

[0048] In some embodiments of this application, the lithium-containing inorganic interface layer includes one or more lithium-containing inorganic materials selected from lithium fluoride, lithium oxide, lithium nitride, lithium carbonate, and lithium nitrate.

[0049] In the embodiments of this application, a dense, nanoscale lithium-containing inorganic material is formed on the surface of the current collector, and the lithium-containing inorganic material interface layer can accelerate the transport of lithium ions in the direction parallel to the electrode surface.

[0050] In some embodiments of this application, the thickness of the lithium-containing inorganic interface layer is 1 nm to 100 nm. Exemplarily, the thickness of the lithium-containing inorganic interface layer is 2, 3, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 31, 33, 34, 35, 37, 39, 40, 42, 44, 45, 47, 49, 50, 52, 54, 55, 57, 58, 60, 61, 62, 64, 65, 66, 68, 69, 70, 71, 73, 74, 76, 78, 79, 80, 82, 83, 84, 86, 87, 89, 90, 91, 93, 95, 96, 98, or 100 nm.

[0051] In some embodiments of this application, the material of the organic interface layer is selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyacrylonitrile, or combinations thereof.

[0052] In some embodiments of this application, the thickness of the organic interface layer is 400 nm to 1000 nm. Exemplarily, the thickness of the organic interface layer is 405, 408, 410, 411, 413, 420, 425, 431, 436, 440, 443, 449, 450, 455, 458, 460, 470, 473, 478, 480, 485, 487, 490, 491, 495, 500, 504, 507, 510, 514, etc. 518, 520, 526, 530, 534, 539, 540, 543, 548, 550, 552, 555, 560, 565, 567, 571, 576, 580, 584, 589, 595, 597, 600, 605, 610, 614, 620, 622, 627, 631, 636, 640, 645, 647 650, 653, 656, 660, 663, 666, 670, 673, 678, 680, 681, 685, 690, 693, 695, 697, 700, 703, 705, 710, 714, 720, 722, 726, 731, 735, 740, 745, 747, 750, 754, 757, 770, 773 ,777,770,773,778,780,781,785,790,794,795,798,800,810,825,830,840,850 , 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 995, 1000nm.

[0053] In some embodiments of this application, the recessed portions are arranged in an array within a first preset region of the organic interface layer. In these embodiments, the recessed portions are arranged in an array within the first preset region of the organic interface layer, uniformly distributed, and have the function of inducing uniform lithium growth. Simultaneously, the overall thickness of the composite interface layer is controllable, the structure is highly designable, and the structure and shape of the directional structure without a negative electrode can be adjusted according to the matching positive electrode and charge / discharge conditions, resulting in high adaptability to practical application scenarios. Exemplarily, the first preset region is rectangular, circular, fan-shaped, elliptical, or triangular. Two or three recessed portions are arranged in a minimum array to form a rectangular or triangular or rectangular array, and multiple arrays are distributed within the first preset region of the organic interface layer.

[0054] In the embodiments of this application, the recesses arranged in an array in the first preset region can induce uniform lithium growth. In particular, for locations where lithium deposition is relatively uneven, multiple recesses arranged in an array can be specifically provided to prevent excessive lithium deposition in specific areas.

[0055] In the embodiments of this application, the array of concave portions can regulate the behavior of lithium deposition / extraction, effectively induce uniform lithium growth within the concave portions, suppress the growth of lithium dendrites, and form a stack-like deposition morphology within the concave portions. This results in low loss of active lithium, improved lithium utilization, and ensures the interfacial stability of the actual fluid and electrolyte, thereby effectively extending the cycle life of the electrodeless battery.

[0056] In some embodiments of this application, the cross-section of the recessed portion along the thickness direction of the organic interface layer is T-shaped, I-shaped, Y-shaped, C-shaped, U-shaped, O-shaped, H-shaped, or cross-shaped. The recessed portions of the above shapes can be obtained by controlling the organic solvent removal conditions or by fabricating using a photomask. The O-shape refers to the formation of a circular solid organic interface layer within the organic interface layer, with an "O"-shaped recessed portion forming around the periphery of this circular organic solid interface layer, extending from the organic interface layer into the lithium-containing inorganic interface layer. The C-shaped recessed portion can be configured similarly to the "O"-shaped recessed portion, except that the C-shaped recessed portion only contains a portion of the O-shape and does not form a completely closed "O"-shaped recessed portion.

[0057] In some embodiments of this application, the recess is an oriented hole extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer.

[0058] In the embodiments of this application, the oriented pores extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer can restrict the morphology of lithium growth. The porous structure of the oriented pores can effectively guide the deposition of lithium metal within the oriented pores, depositing lithium metal in a stacked morphology, and avoiding the formation of lithium dendrites between the current collector and the electrolyte in the oriented structure without a negative electrode.

[0059] In some embodiments of this application, the aperture of the directional aperture is 50 nm to 500 nm. Exemplarily, the aperture of the directional aperture may be selected from 55, 58, 60, 63, 65, 67, 69, 70, 72, 75, 77, 80, 83, 85, 90, 93, 96, 98, 100, 120, 125, 130, 140, 150, 160, 170, 180, 190, 195, 200, 205, 207, 210, 213, 217, 220, 224, 228, 230, 235, 238, 240, 242, 245, 249, 250, 253, 256, 260 nm. 262, 267, 270, 273, 277, 280, 283, 285, 288, 290, 293, 295, 297, 300, 305, 310, 312, 315, 320, 325, 330, 340, 350, 360, 3 70, 380, 390, 395, 400, 410, 420, 430, 440, 442, 450, 455, 460, 463, 470, 471, 476, 480, 484, 488, 490, 492, 496, 500nm.

[0060] In some embodiments of this application, the spacing of the orientation apertures is 10 nm to 2000 nm. Optionally, the spacing of the orientation apertures is 15, 20, 24, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 180, 190, 200, 215, 220, 235, 240, 245, 255, 260, 270, 280, 285, 290, 295, 300, 305, 320, 335, 340, 350, 360, 370, 385, 390, 400, 410, 420, 430, 445 nm. 460, 473, 480, 486, 490, 494, 500, 516, 520, 532, 540, 544, 550, 556, 560, 575, 580, 584, 595, 597, 598, 600, 602, 608, 610, 614, 620, 622, 625, 630, 631, 637, 640, 642, 646, 650, 654, 659, 660, 664, 669, 670, 672, 678, 680, 684, 687 690, 694, 697, 700, 703, 707, 710, 715, 720, 724, 728, 730, 732, 736, 740, 741, 745, 750, 753, 758, 760, 762, 767, 770, 772, 778, 780, 784, 787, 790, 794, 797, 800, 801, 806, 810, 812, 820, 822, 825, 830, 831, 837, 840, 842, 848, 850 ,854,859,860,864,867,870,872,878,880,884,885,890,893,896,900,901,905,910,911,914,920,922,926,9 30, 933, 938, 940, 942, 945, 948, 950, 954, 957, 960, 964, 968, 970, 972, 976, 980, 984, 988, 990, 994, 996, 1000nm.

[0061] In some other embodiments of this application, the spacing of the directional holes may optionally be 1006, 1010, 1012, 1015, 1020, 1024, 1030, 1033, 1040, 1045, 1050, 1056, 1064, 1070, 1073, 1080, 1088, 1090, 1092, 1096, 1100, 1107, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, 1195, 1198, 1199, 1200, 1207, 1210, 1220, 1222, 1226, 1230, 1235, 1238, 1240, 1243, 1 246, 1250, 1254, 1258, 1260, 1264, 1268, 1270, 1271, 1276, 1280, 1282, 1286, 1290, 1292, 1294, 1295, 1298, 1299, 1300, 1305, 1310, 1316, 1320, 1324, 1 330, 1335, 1340, 1344, 1350, 1357, 1360, 1363, 1370, 1378, 1380, 1385, 1387, 1390, 1392, 1395, 1398, 1399, 1400, 1404, 1410, 1416, 1420, 1426, 1430, 1 433, 1440, 1446, 1450, 1452, 1460, 1463, 1467, 1470, 1476, 1480, 1487, 1490, 1493, 1498, 1499, 1500, 1503, 1510, 1512, 1520, 1524, 1530, 1533, 1540 1544, 1550, 1556, 1560, 1566, 1570, 1573, 1580, 1583, 1590, 1595, 1598, 1599, 1600, 1608, 1610, 1614, 1620, 1623, 1630, 1635, 1640, 1647, 1650, 1654, 1660, 1664, 1670, 1676, 1680, 1684, 1690, 1694, 1696, 1699, 1700, 1702, 1710, 1713, 1720, 1723, 1730, 1736, 1740, 1742, 1750, 1753, 1760, 1762, 1770, 1774, 1780, 1788, 1790, 1796, 1795, 1798, 1799, 1800, 1802, 1810, 1812, 1820, 1822, 1830, 1832, 1840, 1842, 1850, 1855, 1860, 1864, 1870, 1878, 18801882, 1890, 1893, 1895, 1897, 1899, 1900, 1910, 1924, 1929, 1935, 1950, 1958, 1964, 1972, 1977, 1980, 1985, 1900, 1995, 2000 nm. Alternatively, the spacing of the directional apertures can be within the range of the above values.

[0062] In some embodiments of this application, the directional holes are arranged in an array. In these embodiments, the directional holes are arranged in an array on the organic interface layer, with uniformly distributed channels, which induces uniform lithium growth. Simultaneously, the overall thickness of the composite interface layer is controllable, the structure is highly designable, and the structure of the directional structure without a negative electrode can be adjusted according to the matching positive electrode and charge / discharge conditions, making it highly adaptable to practical application scenarios.

[0063] In some embodiments of this application, the shape of the cross-section of the directional hole along the thickness direction of the organic interface layer is circular, elliptical, triangular, square, or a regular polygon with more than five sides.

[0064] In some embodiments of this application, the pore diameter d and the pore depth h of the oriented pores satisfy the condition: d / h = 0.05~1. The pore depth h is equal to the thickness of the organic interface layer. The pore diameter d and pore depth satisfying the above relationship make it easier for lithium to deposit within the oriented pores. Specifically, the larger the value of d / h, the easier it is for lithium to deposit in the oriented pores. Optionally, the value of d / h is 0.08, 0.1, 0.25, 0.3, 0.45, 0.5, 0.6, 0.7, 0.75, 0.8, 0.83, 0.9, 0.95, 0.98, or 1.

[0065] In some embodiments of this application, the aperture of the directional holes gradually decreases from large to small along the direction from the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer. This facilitates more efficient deposition of metallic lithium in the direction from the organic interface layer to the lithium-containing inorganic interface layer, forming a stacked lithium metal deposition morphology and extending the lifespan of the lithium metal battery. Optionally, the longitudinal section of the directional holes along their central axis is tapered in a trumpet shape, trapezoidal shape, or stepped shape, or approximately both of these shapes, along the direction from the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer, to form a stacked lithium deposition morphology.

[0066] Secondly, this application provides a method for preparing a directional structured negative electrode, comprising:

[0067] S1, Provides a current collector;

[0068] S2. Lithium-containing inorganic materials are deposited on at least one side of the current collector using vacuum thermal evaporation or atomic layer deposition to form a lithium-containing inorganic interface layer.

[0069] S3. An organic interface layer is formed on the side of the lithium-containing inorganic interface layer away from the current collector, and a concave portion is formed on the organic interface layer extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the inner part of the lithium-containing inorganic interface layer; a composite interface layer is formed by the lithium-containing inorganic interface layer and the organic interface layer.

[0070] In some embodiments of this application, the current collector includes:

[0071] S101. The data collector is soaked in a cleaning solution to facilitate rinsing.

[0072] S102. Rinse the soaked current collector with anhydrous ethanol.

[0073] S103. The current collector that has been rinsed is dried to remove anhydrous ethanol.

[0074] In the embodiments of this application, surface treatment of the current collector can improve the lithium deposition interface environment and regulate the lithium deposition morphology, which is an effective measure to achieve stacked lithium metal deposition.

[0075] In some embodiments of this application, the cleaning solution is acetone. The current collector after rinsing can be dried in an environment of 75°C to 90°C.

[0076] In some embodiments of this application, forming a lithium-containing inorganic interface layer on the surface of the current collector includes: depositing lithium-containing inorganic materials onto the surface of the current collector using vacuum thermal evaporation or atomic layer deposition (ALD) to form the lithium-containing inorganic interface layer. Vacuum thermal evaporation refers to a process in which lithium-containing inorganic materials are vaporized under vacuum conditions, and the lithium-containing inorganic particles are deposited onto the surface of the current collector, which is pre-placed above them, to condense into a film layer (i.e., the lithium-containing inorganic interface layer). Atomic layer deposition (ALD) is a surface treatment method that deposits lithium-containing inorganic materials layer by layer onto the surface of the current collector in the form of a single atomic film. Specifically, this can be achieved by alternately introducing inorganic material sources such as lithium and fluorine sources into the cavity to obtain the lithium-containing inorganic interface layer on the surface of the current collector. When forming the lithium-containing inorganic interface layer using ALD, the thickness of the film can be controlled by controlling the number of deposition cycles.

[0077] In some embodiments of this application, forming an organic interface layer on the side of the lithium-containing inorganic interface layer away from the current collector includes:

[0078] S2021. A precursor treatment solution is prepared using organic materials and a first organic solvent;

[0079] S2022. The precursor treatment liquid is coated on the surface of the lithium-containing inorganic interface layer away from the current collector to form a first electrode containing the precursor coating.

[0080] S2023. The first electrode is dried at 30℃~60℃ for 2 hours to 4 hours to obtain a first electrode containing an organic layer.

[0081] S2024. The first electrode containing the organic layer is dried at 40℃~60℃ for 12 hours~36 hours to form an oriented structure without a negative electrode containing an organic interface layer.

[0082] In the embodiments of this application, by coating the surface of the lithium-containing inorganic interface layer away from the current collector with a precursor treatment liquid and drying to form an organic interface layer, an organic interface layer with oriented pores of 200 nm to 300 nm in diameter and 500 nm to 700 nm in spacing can be prepared.

[0083] In some embodiments of this application, forming an organic interface layer on the side of the lithium-containing inorganic interface layer away from the current collector includes:

[0084] S2021. A precursor treatment solution is prepared using organic materials and a first organic solvent;

[0085] S2022. A mask is placed on the surface of the lithium-containing inorganic interface layer away from the current collector, and the precursor treatment liquid is coated onto the mask in a dry chamber to form a first electrode containing a precursor coating.

[0086] S2023. The first electrode is dried at 30℃~60℃ for 2 hours to 4 hours to obtain a first electrode containing an organic layer.

[0087] S2024. Dry the first electrode containing the organic layer at 40°C to 60°C for 12 to 36 hours.

[0088] S2025. Remove the mask with a second organic solvent to obtain a directional structured electrode without a negative electrode containing an organic interface layer.

[0089] In the embodiments of this application, by using a mask and coating with a precursor treatment solution on the side of the lithium-containing inorganic interface layer facing away from the current collector, and then drying to form an organic interface layer, an organic interface layer with oriented pores of various shapes, pore sizes ranging from 100 nm to 500 nm, and pore spacings ranging from 400 nm to 800 nm, can be prepared. A dry room refers to an indoor environment with relatively low humidity and a dew point of -40°C.

[0090] In embodiments of this application, oriented holes of different apertures can be obtained by controlling the drying temperature and drying time of the first electrode and the first electrode containing the organic layer. Furthermore, concave portions with different cross-sectional shapes along the thickness direction of the organic interface layer can be obtained by combining a photomask.

[0091] In some embodiments of this application, the first organic solvent is one or a combination of several of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and acetonitrile (AN).

[0092] In some embodiments of this application, organic materials and a first organic solvent are formulated into a precursor treatment solution at a mass ratio of (1-10):(1-10).

[0093] In some embodiments of this application, the photomask is made of PMMA material, and correspondingly, acetone is used as a second organic solvent to impregnate the photomask and to rinse and remove the photomask.

[0094] In some embodiments of this application, the precursor treatment liquid is coated onto a photomask by spin coating, spraying, or scraping.

[0095] In the embodiments of this application, the composite interface layer can be prepared using semiconductor equipment, which can give full play to the advantages of semiconductor equipment, has a wide range of applications, has little impact on battery energy density, and is highly adaptable to practical scenarios. It is an effective preparation method for oriented structure negative electrode-free electrodes.

[0096] Thirdly, this application provides an electrochemical device comprising: the above-described oriented structure without a negative electrode.

[0097] In the embodiments of this application, the electrochemical device is a rechargeable secondary battery or an energy storage device. Optionally, in a coin cell, the composite interface layer may be disposed only on one side of the current collector to form an oriented structure without a negative electrode, thus enabling its application in a coin cell. In a stacked pouch cell, the composite interface layer needs to be disposed on both sides of the current collector to form an oriented structure without a negative electrode, thus enabling its application in a stacked pouch cell.

[0098] In the embodiments of this application, any raw materials or reagents not specifically described in the specification can be obtained through commercial channels.

[0099] Test section

[0100] I. Preparation of Directional Structured Negative Electrode

[0101] Example 1

[0102] A method for preparing a directional, negative electrode-free structure, comprising:

[0103] S1. Provide current collectors, including:

[0104] S101. Cut copper foil to 6cm×7cm and soak the copper foil, which is used as the current collector, in acetone as a cleaning solution to facilitate rinsing of the current collector.

[0105] S102. The current collector that has been soaked is rinsed multiple times with anhydrous ethanol.

[0106] S103. The rinsed current collector is dried at 80°C to remove anhydrous ethanol for later use. S2. A composite interface layer is formed on at least one surface of the current collector, comprising:

[0107] S201. A lithium-containing inorganic interface layer is formed on the surface of the current collector treated in step S1 by vacuum thermal evaporation of lithium fluoride powder. The voltage and current of the evaporation power supply are 0.8V and 58A, respectively, the working distance is 320nm, and the pressure is 8×10⁻⁶. -4 Pa, evaporation rate is The thickness of the lithium fluoride inorganic interface layer is 5 nm.

[0108] S202. An organic interface layer is formed on the side of the lithium fluoride inorganic interface layer away from the current collector, including:

[0109] S2021. A precursor treatment solution was prepared using 1g of polyvinylidene fluoride (PVDF) as the organic material and 3.8g of N,N-dimethylformamide as the first organic solvent.

[0110] S2022. The precursor treatment liquid is added to the surface of the lithium fluoride inorganic interface layer away from the current collector, and then spin-coated sequentially at 300 r / min for 30 s, 1000 r / min for 10 s, 3000 r / min for 20 s, and 5000 r / min for 20 s to form a first electrode containing a precursor coating.

[0111] S2023. The first electrode containing the precursor coating is transferred to an oven and dried at 40°C for 2 hours to obtain the first electrode containing an organic layer.

[0112] S2024. The first electrode containing the organic layer is transferred to a vacuum oven and further dried at 60°C for 12 hours to remove excess first organic solvent, resulting in a directional structure negative electrode containing an organic interface layer. The organic interface layer has a thickness of 400 nm and is continuously distributed with directional pores of 300 nm in diameter and a spacing of 500 nm to 800 nm.

[0113] like Figure 2 As shown, the thickness of the lithium fluoride inorganic interface layer is approximately 5 nm; Figure 3 As shown, the morphology of the lithium fluoride inorganic interface layer has a surface roughness of 1.7 nm. Figure 4 The image shows the surface morphology of the PVDF organic interface layer, which has oriented pores with a diameter of 300 nm distributed on its surface.

[0114] Example 2

[0115] A method for preparing a directional, negative electrode-free structure, comprising:

[0116] S1. Provide current collectors, including:

[0117] S101. Cut copper foil to 3cm×4cm and soak the copper foil, which is used as the current collector, in acetone as a cleaning solution to facilitate rinsing of the current collector.

[0118] S102. The current collector that has been soaked is rinsed multiple times with anhydrous ethanol.

[0119] S103. The rinsed current collector is dried at 80°C to remove anhydrous ethanol for later use. S2. A composite interface layer is formed on at least one surface of the current collector, comprising:

[0120] S201. A lithium-containing inorganic interface layer is formed on the surface of the current collector treated in step S1 by vacuum thermal evaporation of lithium nitride powder. The voltage and current of the evaporation power supply are 0.1V and 60A, respectively, the working distance is 320nm, and the pressure is 8×10⁻⁶. -4 Pa, evaporation rate is The thickness of the lithium nitride inorganic interface layer is 5 nm.

[0121] S202. An organic interface layer is formed on the side of the lithium nitride inorganic interface layer away from the current collector, including:

[0122] S2021, A precursor treatment solution was prepared using 0.9g of polyvinylidene fluoride (PVDF) and 0.1g of polyacrylonitrile (PAN) as organic materials and 3.8g of N,N-dimethylformamide as the first organic solvent.

[0123] S2022. A mask is placed over the surface of the lithium nitride inorganic interface layer away from the current collector. In a dry chamber, a dropper is used to add the precursor treatment solution onto the mask. The solution is then spin-coated sequentially at 300 r / min for 30 s, 1000 r / min for 10 s, 3000 r / min for 20 s, and 5000 r / min for 20 s to form the first electrode containing the precursor coating.

[0124] S2023. The first electrode containing the precursor coating is transferred to an oven and dried at 30°C for 2 hours to obtain the first electrode containing an organic layer.

[0125] S2024. Transfer the first electrode containing the organic layer to a vacuum oven and dry it further at 60°C for 12 hours to remove excess first organic solvent.

[0126] S2025. The mask is impregnated with acetone as a second organic solvent and then rinsed off to obtain a directional structured negative electrode containing an organic interface layer. The organic interface layer has a thickness of 500 nm and is continuously distributed with directional holes of 300 nm in diameter and 300 nm to 900 nm in spacing.

[0127] like Figure 5 As shown, the thickness of the lithium nitride inorganic interface layer is approximately 5 nm; Figure 6 The image shows the surface morphology of the lithium nitride inorganic interface layer, with a surface roughness of 5.91 nm.

[0128] Example 3

[0129] A method for preparing a directional, negative electrode-free structure, comprising:

[0130] S1. Provide current collectors, including:

[0131] S101. Cut copper foil to 10cm×10cm, and soak the copper foil, which is used as the current collector, in acetone as a cleaning solution to facilitate rinsing of the current collector.

[0132] S102. The current collector that has been soaked is rinsed multiple times with anhydrous ethanol.

[0133] S103. The rinsed current collector is dried at 80°C to remove anhydrous ethanol for later use. S2. A composite interface layer is formed on at least one surface of the current collector, comprising:

[0134] S201. A lithium-containing inorganic interface layer is formed on the surface of the current collector treated in step S1 by vacuum thermal evaporation of lithium nitride powder. The voltage and current of the evaporation power supply are 1V and 60A, respectively, the working distance is 320nm, and the pressure is 8×10⁻⁶. -4 Pa, evaporation rate is The thickness of the lithium nitride inorganic interface layer is 5 nm.

[0135] S202. An organic interface layer is formed on the side of the lithium nitride inorganic interface layer away from the current collector, including:

[0136] S2021. A precursor treatment solution was prepared using 0.5g of polyethylene oxide (PEO) as the organic material and 3.8g of N,N-dimethylformamide as the first organic solvent.

[0137] S2022. A mask is placed over the surface of the lithium nitride inorganic interface layer away from the current collector. In a dry chamber, a dropper is used to add the precursor treatment solution onto the mask. The solution is then spin-coated sequentially at 300 r / min for 30 s, 1000 r / min for 10 s, 3000 r / min for 20 s, and 5000 r / min for 20 s to form the first electrode containing the precursor coating.

[0138] S2023. The first electrode containing the precursor coating is transferred to an oven and dried at 40°C for 2 hours to obtain the first electrode containing an organic layer.

[0139] S2024. Transfer the first electrode containing the organic layer to a vacuum oven and dry it further at 60°C for 12 hours to remove excess first organic solvent.

[0140] S2025. The mask is impregnated with acetone as a second organic solvent and then rinsed off to obtain a directional structured negative electrode containing an organic interface layer. The organic interface layer has a thickness of 300 nm and is continuously distributed with directional holes of 300 nm in diameter and 500 nm to 700 nm in spacing.

[0141] Comparative Example 1

[0142] A lithium metal battery includes a negative electrode and a positive electrode immersed in an electrolyte solution, and a PE separator separating the positive and negative electrodes. The concentration of LiFSI in the electrolyte solution is 1.67 mol / L, and the electrolyte solution includes ethylene glycol dimethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether in a volume ratio of 1:2, and 0.167 mol / L of lithium hexafluorophosphate as an additive. The positive electrode uses aluminum foil as a current collector, and NCM811 is coated on the aluminum foil as a ternary positive electrode material. The areal capacity of the positive electrode is 4.5 mAh·cm³. -2 The negative electrode uses copper foil as the current collector and contains no other substances. The copper foil undergoes the same cleaning treatment as S101-S103 in Example 1.

[0143] II. Electrochemical Performance Testing

[0144] The oriented negative electrode structures prepared in Examples 1-3 were applied to a coin cell for electrochemical performance testing. The coin cell included a positive electrode sheet, which used aluminum foil as a current collector and coated the aluminum foil with NCM811 as the ternary positive electrode material. The areal capacity of the positive electrode sheet was 4.5 mAh·cm³. -2The concentration of LiFSI in the electrolyte solution was 1.67 mol / L, and the electrolyte solution consisted of ethylene glycol dimethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether in a volume ratio of 1:2. The electrochemical cycling performance was tested under the following conditions: voltage range of 2.8–4.3 V; after two pre-cycles at 0.1C, cycling was performed under 0.2C charging and 2C discharging conditions.

[0145] (1) Coulomb efficiency test

[0146] like Figure 7 As shown, the negative-electrode-free batteries fabricated using the oriented structure negative-electrode prepared in Examples 1-3 of this application maintain a coulombic efficiency of approximately 100% from the start of cycling up to 100 cycles. This indicates that the oriented structure negative-electrode-free batteries with an interface composite layer and oriented pores in the organic interface layer prepared in the examples of this application have a high coulombic efficiency, significantly higher than the negative electrode of Comparative Example 1 without a composite interface layer and oriented pores. Overall, the oriented structure negative-electrode-free battery prepared in Example 2 exhibits the highest coulombic efficiency in a negative-electrode-free lithium metal battery, followed by the oriented structure negative-electrode-free batteries prepared in Examples 1 and 3. However, the coulombic efficiency of the oriented structure negative-electrode-free battery prepared in Example 1 is initially higher than that of the oriented structure negative-electrode-free battery prepared in Example 3.

[0147] (2) Cyclic performance test

[0148] like Figure 8 As shown, when the oriented structure electrode without negative electrode prepared in Examples 1-3 of this application is applied to an electrodeless battery, after 100 cycles, the capacity of the oriented structure electrode without negative electrode prepared in Example 1 applied to a lithium metal battery still remains at 2.8 mAh·cm⁻¹. -2 The capacity retention rate was 62.22%; the capacity of the oriented structure without a negative electrode in Example 2, after being applied to a lithium metal battery, remained at 2.95 mAh·cm⁻¹. -2 The capacity retention rate was 65.55%; the capacity of the oriented structure without a negative electrode in Example 3, after being applied to a lithium metal battery, remained at 2.75 mAh·cm⁻¹. -2 The capacity retention rate was 61.11%. However, this is higher than that of the 1mAh·cm³ lithium metal battery without a negative electrode in Comparative Example 1, which uses copper foil itself as the negative electrode. -2The electrode exhibits a high capacity retention rate of 22.22%. The oriented structure electrode with oriented pores, comprising a composite interface layer and an organic interface layer, prepared in Examples 1-3, still maintains a high capacity retention rate after 100 cycles in an electrodeless battery. This demonstrates that the oriented structure electrode of this application ensures interface stability, thereby effectively extending the cycle life of the electrodeless battery and maintaining a relatively high capacity retention rate.

[0149] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A directional structure without a negative electrode, characterized in that, include: Current collector (1), wherein the current collector is a copper current collector; A composite interface layer (2) that covers at least one side surface of the current collector (1); The composite interface layer (2) includes: a lithium-containing inorganic interface layer (201), which is disposed on at least one side surface of the current collector (1), the thickness of the lithium-containing inorganic interface layer is 1 nm to 100 nm, and the lithium-containing inorganic interface layer includes one or more lithium-containing inorganic materials selected from lithium fluoride, lithium oxide, lithium nitride, lithium carbonate, and lithium nitrate; and an organic interface layer (202), which is disposed on the side of the lithium-containing inorganic interface layer (201) away from the current collector (1), the organic interface layer (202) is provided with a plurality of recesses (2021) dispersed or continuously, the recesses (2021) extending from the surface of the organic interface layer (202) away from the lithium-containing inorganic interface layer (201) to the lithium-containing inorganic interface layer (201), the thickness of the organic interface layer is 400 nm to 1000 nm, and the material of the organic interface layer is selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polyacrylonitrile, or combinations thereof.

2. The directional structure without a negative electrode according to claim 1, characterized in that, The recessed portion (2021) is arranged in an array within the first preset area of ​​the organic interface layer.

3. The directional structure without a negative electrode according to claim 1, characterized in that, The concave portion has a cross-section along the thickness direction of the organic interface layer that is T-shaped, I-shaped, Y-shaped, C-shaped, U-shaped, O-shaped, H-shaped, or cross-shaped.

4. The directional structure without a negative electrode according to claim 1, characterized in that, The recessed portion is an oriented hole extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the lithium-containing inorganic interface layer.

5. The directional structure without a negative electrode according to claim 4, characterized in that, The orientation hole must meet at least one of the following requirements: The aperture of the directional aperture is 50nm to 500nm; The spacing of the directional apertures is 10nm to 2000nm; The directional holes are arranged in an array; The shape of the cross-section of the directional hole along the thickness direction of the organic interface layer is circular, elliptical, triangular, square, or a regular polygon with more than five sides.

6. The directional structure without a negative electrode according to claim 4, characterized in that, The diameter d and the depth h of the directional hole satisfy the following condition: d / h = 0.05~1.

7. The directional structure without a negative electrode according to claim 1, characterized in that, The copper current collector is selected from at least one of smooth copper foil, matte copper foil, mesh copper foil, foam copper foil, and polymer composite copper foil.

8. The method for preparing the oriented structure without a negative electrode according to any one of claims 1-7, characterized in that, include: Provide current collectors; Lithium-containing inorganic materials are deposited on at least one side surface of the current collector using vacuum thermal evaporation or atomic layer deposition to form a lithium-containing inorganic interface layer; An organic interface layer is formed on the side of the lithium-containing inorganic interface layer away from the current collector, and a recess is formed on the organic interface layer extending from the surface of the organic interface layer away from the lithium-containing inorganic interface layer to the inner portion of the lithium-containing inorganic interface layer; a composite interface layer is formed by the lithium-containing inorganic interface layer and the organic interface layer.

9. The method for preparing a directional structure without a negative electrode according to claim 8, characterized in that, The formation of an organic interface layer on the side of the lithium-containing inorganic interface layer opposite to the current collector includes: A precursor treatment solution was prepared using organic materials and a first organic solvent; The precursor treatment liquid is coated onto the surface of the lithium-containing inorganic interface layer away from the current collector to form a first electrode containing a precursor coating. The first electrode is dried at 30°C to 60°C for 2 to 4 hours to obtain a first electrode containing an organic interface layer. The first electrode containing the organic interface layer is dried at 40°C to 60°C for 12 to 36 hours to obtain a directional structured negative electrode containing the organic interface layer; or The formation of the organic interface layer on the side of the lithium-containing inorganic interface layer opposite to the current collector includes: A precursor treatment solution was prepared using organic materials and a first organic solvent; A mask is placed over the surface of the lithium-containing inorganic interface layer away from the current collector, and the precursor treatment liquid is coated onto the mask in a dry chamber to form a first electrode containing a precursor coating. The first electrode is dried at 30°C to 60°C for 2 to 4 hours to obtain a first electrode containing an organic layer. The first electrode containing the organic layer is dried at 40°C to 60°C for 12 to 36 hours. The mask is removed using a second organic solvent to obtain a oriented structured electrode without a negative electrode containing an organic interface layer.

10. The method for preparing a directional structure without a negative electrode according to claim 9, characterized in that, The first organic solvent is one or a combination of N,N-dimethylformamide, N-methylpyrrolidone, and acetonitrile; and / or The organic material and the first organic solvent are mixed in a mass ratio of (1-10): (1-10) to form a precursor treatment solution.

11. An electrochemical device, characterized in that, include: The directional structure according to any one of claims 1-7 has no negative electrode.

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