Coating for negative electrode and solid-state battery including same

Abstract

Disclosed is a coating made from two elements (A and B) and a carbonaceous material, where element A is capable of alloying with lithium and element B is not capable of alloying with lithium. Methods for preparing the coating and an all-solid-state battery (ASSB) comprising the same are also disclosed. In one embodiment, the ASSB comprising the coating exhibits reduced charging overpotential and improved specific capacity and cycle life.

Description

Description of Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 517,364, filed August 3, 2023, and U.S. Provisional Patent Application No. 63 / 498,545, filed April 27, 2023, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a coating made from two elements (A and B) and a carbonaceous material, where element A is capable of alloying with lithium and element B is not capable of alloying with lithium. A solid-state battery comprising the coating is also disclosed. [Background technology]

[0003] Lithium metal anodes are more promising than other types of anodes (e.g., graphite-based anodes) for high-energy-density all-solid-state batteries (ASSBs) due to their theoretical capacity (3,860 mAh / g). However, the formation of lithium dendrites can cause safety issues and shorten cycle life. It has been shown that a nanocomposite layer of Ag / C on a lithium metal anode can result in improved cycle life. Silver nanoparticles tend to form agglomerates, which can exacerbate safety issues by accelerating the growth of lithium dendrites. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, new negative electrode designs are still needed. [Means for solving the problem]

[0005] The present disclosure provides an anode coating (or layer) made from two elements (A and B) and a carbonaceous material, where element A is capable of alloying with lithium and element B is not capable of alloying with lithium. A method for preparing the anode coating and an all-solid-state battery (ASSB) comprising the same are also disclosed. [Brief explanation of the drawings]

[0006] Non-limiting embodiments of the present disclosure are described, by way of example, with reference to the accompanying drawings, which are schematic and are not intended to be drawn to scale. In the drawings, each identical or nearly identical component illustrated is typically designated by a single number. For clarity, not every component is numbered in every drawing, nor is every component of every embodiment of the present disclosure shown, unless illustration is necessary for those skilled in the art to understand the disclosure. [Figure 1] Schematic diagram showing a coating (1) comprising particles of element A (2), particles of element B (3), and a carbonaceous material (4) on an anode current collector (5) according to one embodiment of the present disclosure. [Figure 2] Schematic diagram showing a coating (1) comprising particles of element A (2), particles of element B (3), and a carbonaceous material (4) on an anode active material layer (6) comprising lithium metal, according to one embodiment of the present disclosure. [Figure 3] Graph showing the rate capabilities of batteries with coatings of Reference Example (Ref. Ex), Comparative Example 1 (Comp. Ex 1), Comparative Example 2 (Comp. Ex 2), Comparative Example 3 (Comp. Ex 3), Example 1 (Ex 1), Example 2 (Ex 2), Example 3 (Ex 3), Example 4 (Ex 4), Example 5 (Ex 5), and Example 6 (Ex 6), according to some embodiments of the present disclosure. [Figure 4] Graph showing discharge capacity cycling performance of batteries with coatings of Reference Example (Ref. Ex), Comparative Example 1 (Comp. Ex 1), Comparative Example 2 (Comp. Ex 2), Comparative Example 3 (Comp. Ex 3), Example 4 (Ex 4), and Example 5 (Ex 5), according to some embodiments of the present disclosure. [Figure 5] SEM image of Ag / C containing coating prepared according to the reference example [Figure 6] SEM image of a coating comprising Zn as element A, Cu as element B, and a carbonaceous material according to Example 4 [Figure 7] Graph showing electrochemical impedance spectroscopy (EIS) results for Reference Example (Ref. Ex) and Example 4 (Ex 4) before and after rate capability testing. [Figure 8] 1 is a graph showing half-cell testing of high discharge rate capability of Example 5 versus the reference example up to 5.5C (IC=170mAh) according to one embodiment of the present disclosure. [Figure 9] 1 is a graph showing half-cell testing of cycle performance of Example 5 vs. the reference example based on 0.33 C (1 C=170 mAh), according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0007] Disclosed herein are coatings that, when incorporated into solid-state batteries, provide desirable cycle life and safety benefits. In some embodiments, the coating (or layer) comprises at least two metal or metalloid elements (A and B) and a carbonaceous material, where element A is capable of alloying with lithium and element B is not. In some embodiments, the coatings disclosed herein are for a negative electrode, such as an anode. In some embodiments, the coating is an interfacial layer between a negative electrode and an electrolyte in an electrochemical device. In some embodiments, the coating is in direct contact with a negative electrode current collector or a negative electrode or a negative electrode active material layer. As used herein, "negative electrode" can refer to a negative electrode current collector, a negative electrode active material layer, or a combination of the two. For example, as shown in FIG. 1, the coating (1) comprises particles of element A (2) capable of alloying with lithium and particles of element B (3) not capable of alloying with lithium, dispersed in a carbonaceous material (4). Depending on the particular solid-state battery configuration, the coating (1) can be disposed on an anode current collector (5), as shown in Figure 1. In other embodiments, as shown in Figure 2, the coating (1) can be disposed on an anode active material layer (6), e.g., lithium metal, which is in turn disposed on the anode current collector (5).

[0008] In some embodiments, the carbonaceous material comprises at least one selected from the group consisting of carbon fibers, carbon nanotubes, carbon wires, natural graphite, artificial graphite, graphene, carbon black, acetylene black, and ketjen black. In some embodiments, the carbonaceous material takes the form of a material selected from the group consisting of nanoparticles, nanoplatelets, nanowires, nanotubes, and combinations thereof. In some embodiments, the nanoparticles, nanoplatelets, nanowires, and nanotubes have at least one dimension less than or equal to 100 nm. In some embodiments, the carbonaceous material comprises a volume percentage of 50% or greater in the coating.

[0009] In some embodiments, element A is selected for its ability to form an alloy with lithium atoms or ions, and therefore, element A can alloy with lithium. In some embodiments, element A and lithium can form an alloy where the lithium has a mass percentage of 4% or more, 10% or more, 15% or more, 20% or more, 25% or more, or 30% or more in the alloy. In some embodiments, element A and lithium can form an alloy where the lithium has a mass percentage of 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less in the alloy.

[0010] In some embodiments, element A is a metal or a metalloid. In some embodiments, element A is at least one selected from the group consisting of Ag, Zn, Ti, Cd, Mg, Al, Ga, Si, Ge, In, Sn, Pb, Bi, Sb, and mixtures thereof. In some embodiments, element A does not include Ag. In some embodiments, when the coating is disposed on the negative electrode, particles of element A may migrate or migrate over time within the carbonaceous material and concentrate or agglomerate in areas adjacent to the negative electrode, or even within the negative electrode, due to lithium in the negative electrode active material and / or lithium that accumulates in the negative electrode during discharge. If too many particles of element A agglomerate, lithium dendrites may form, shorting the battery cell; therefore, in some embodiments, element A comprises a mass percentage of the coating of 17.5% or less. In some embodiments, element A has a weight percentage in the coating ranging from 1% to 17.5%, 2.5% to 17.5%, 5% to 17.5%, 7.5% to 17.5%, 1% to 15%, 2% to 15%, 3% to 15%, 4% to 15%, 5% to 15%, 7.5% to 15%, 1% to 12.5%, 2% to 12.5%, 3% to 12.5%, 5% to 12.5%, 7.5% to 12.5%, 1% to 10%, 2% to 10%, 3% to 10%, 5% to 10%, 7.5% to 10%, and any and all ranges and subranges therebetween. In some embodiments, element A can be an elemental compound capable of alloying with lithium, such as a silicon compound and a tin alloy. In some embodiments, the silicon compound is SiO x where 0.5≦x≦1.5. In some embodiments, specific non-limiting tin alloys include Cu·Sn alloys, Co·Sn alloys, etc. In some embodiments, the coating is substantially free of agglomerates of element A and element B when viewed in cross section through the coating by SEM.

[0011] In some embodiments, element B is chosen for its ability to not alloy with lithium ions or atoms; therefore, element B cannot alloy with lithium. Without being bound by theory, it is believed that because element B cannot alloy with lithium, particles of element B do not migrate or agglomerate within the carbonaceous material as do element A. In some embodiments, element B has a higher electrical conductivity than the electrical conductivity of the carbonaceous material and / or element A, thereby increasing the electrical conductivity of the coating.

[0012] In some embodiments, the element B is at least one selected from the group consisting of Cu, Mo, Ir, W, Co, Ni, Ru, Fe, Se, Ta, Nb, V, Zr, and mixtures thereof. In some embodiments, the element B has a mass percentage in the coating ranging from 3% to 15%. In some embodiments, element B has a weight percentage in the coating ranging from 1% to 17.5%, 2.5% to 17.5%, 5% to 17.5%, 7.5% to 17.5%, 1% to 15%, 2% to 15%, 3% to 15%, 4% to 15%, 5% to 15%, 7.5% to 15%, 1% to 12.5%, 2% to 12.5%, 3% to 12.5%, 5% to 12.5%, 7.5% to 12.5%, 1% to 10%, 2% to 10%, 3% to 10%, 5% to 10%, 7.5% to 10%, and any and all ranges and sub-ranges therebetween.

[0013] In some embodiments, the electrical conductivity of element B is higher than that of element A to increase the electrical conductivity of the coating. In some embodiments, the ratio of the electrical conductivity of element B to the electrical conductivity of element A is in the range of 1 to 30, 2.5 to 30, 5 to 30, 10 to 30, 1 to 25, 2.5 to 25, 5 to 25, 10 to 25, 1 to 20, 2.5 to 20, 5 to 20, 10 to 20, 1 to 15, 2.5 to 15, 5 to 15, 10 to 15, 1 to 10, 2.5 to 10, 5 to 10, and any and all ranges and sub-ranges therebetween. In some embodiments, the ratio of the electrical conductivity of element B to the electrical conductivity of element A is less than 1. In some embodiments, the ratio of the electrical conductivity of element B to the electrical conductivity of element A is in the range of 0.2 to 1.0, 0.5 to 1.0, or 0.75 to 1.0.

[0014] In some embodiments, the mass ratio of element A to element B is in the range of 1:99 to 50:50. In some embodiments, the mass ratio of element A to element B is in the range of 1:99 to 50:50, 2:98 to 50:50, 3:97 to 50:50, 4:96 to 50:50, 5:99 to 50:50, 7.5:92.5 to 50:50, 10:90 to 50:50, 15:85 to 50:50, 20:80 to 50:50, 1:99 to 55:45, 2:98 to 55:45, 3:97 to 55:45, 4:96 to 55:45, 5:95 to 55:4 5, 7.5:92.5 to 55:45, 10:90 to 55:45, 15:85 to 55:45, 20:80 to 55:45, 1:99 to 60:40, 2:98 to 60:40, 3:97 to 60:40, 4:96 to 60:40, 5:95 to 60:40, 7.5:92.5 to 60:40, 10:90 to 60:40, 15:85 to 60:40, 20:80 to 60:40, and any and all ranges and sub-ranges therebetween.

[0015] In some embodiments, the total weight percentage of elements A and B in the coating (weight % of element A + weight % of element B) ranges from 5% to 20% of the coating. In some embodiments, the total weight percentage of elements A and B is in the range from 1% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 12.5%, 1% to 10%, 2.5% to 30%, 2.5% to 20%, 2.5% to 15%, 2.5% to 10%, 5% to 30%, 5% to 25%, 5% to 20%, 5% to 15%, 5% to 10%, 7.5% to 30%, 7.5% to 25%, 7.5% to 20%, 7.5% to 15%, 7.5% to 10%, 10% to 30%, 10% to 25%, 10% to 20%, 10% to 15%, and any and all ranges and sub-ranges therebetween.

[0016] In some embodiments, the total volume percentage of elements A and B (volume % of element A + volume % of element B) in the coating is in the range of 1% to 15%. In some embodiments, the total volume percentage of elements A and B in the coating is in the range of 1% to 25%, 1% to 20%, 1% to 15%, 1% to 12.5%, 1% to 10%, 2.5% to 20%, 2.5% to 15%, 2.5% to 10%, 5% to 25%, 5% to 20%, 5% to 15%, 5% to 10%, 7.5% to 25%, 7.5% to 20%, 7.5% to 15%, 7.5% to 10%, 10% to 25%, 10% to 20%, 10% to 15%, and any and all ranges and sub-ranges therebetween.

[0017] In some embodiments, element A, element B, or both may be in the form of nanoparticles in the coating. In such embodiments, the nanoparticles may have an average particle size (D50) ranging from 20 nm to 80 nm. In some embodiments, the average particle size is 10 nm to 200 nm, 10 nm to 175 nm, 10 nm to 150 nm, 10 nm to 125 nm, 10 nm to 100 nm, 10 nm to 80 nm, 10 nm to 60 nm, 10 nm to 50 nm, 15 nm to 200 nm, 15 nm to 175 nm, 15 nm to 150 nm, 15 nm to 125 nm, 15 nm to 100 nm, 15 nm to 80 nm, 15 nm to 60 nm, 15 nm to 50 nm, In the ranges of 20nm to 200nm, 20nm to 175nm, 20nm to 150nm, 20nm to 125nm, 20nm to 100nm, 20nm to 80nm, 20nm to 60nm, 20nm to 50nm, 25nm to 200nm, 25nm to 175nm, 25nm to 150nm, 25nm to 125nm, 25nm to 100nm, 25nm to 80nm, 25nm to 60nm, and any and all ranges and sub-ranges therebetween.

[0018] In some embodiments, the coating has a thickness ranging from 0.1 μm to 50 μm, 0.05 μm to 100 μm, 0.1 μm to 100 μm, 0.25 μm to 100 μm, 0.5 μm to 100 μm, 1 μm to 100 μm, 2.5 μm to 100 μm, 5 μm to 100 μm, 10 μm to 100 μm, 0.05 μm to 75 μm, 0.1 μm to 75μm, 0.25μm to 75μm, 0.5μm to 75μm, 1μm to 75μm, 2.5μm to 75μm, 5μm to 75μm, 10μm to 75μm, 0.1μm to 50μm, 0.25μm to 50μm, 0.5μm to 50μm, 1μm to 50μm, 2.5μm to 50μm, 5μm to 50μm, 10μ m to 50μm, 0.05μm to 25μm, 0.1μm to 25μm, 0.25μm to 25μm, 0.5μm to 25μm, 1μm to 25μm, 2.5μm to 25μm, 5μm to 25μm, 10μm to 25μm, 0.05μm to 20μm, 0.1μm to 20μm, 0.25μm to 20μm, 0.5μm to 20 μm, 1 μm to 20 μm, 2.5 μm to 20 μm, 5 μm to 20 μm, 10 μm to 20 μm, 0.05 μm to 10 μm, 0.1 μm to 10 μm, 0.25 μm to 10 μm, 0.5 μm to 10 μm, 1 μm to 10 μm, 2.5 μm to 10 μm, or 5 μm to 10 μm.

[0019] In some embodiments, the coating may also include a binder. The binder may be a polymer. In some embodiments, the binder may be at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride / hexafluoropropylene copolymer, polyimide, polyethylene, polyester, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose / styrene-butadiene rubber (CMC / SBR) copolymer, styrene-butadiene rubber (SBR), and mixtures thereof. In some embodiments, the binder has a weight percentage in the coating ranging from 1% to 20%. In some embodiments, the binder has a weight percentage in the coating ranging from 1% to 15%, 1% to 10%, 1% to 7.5%, 1% to 5%, 2% to 15%, 2% to 10%, 2% to 7.5%, 2% to 5%, 2.5% to 15%, 2.5% to 10%, 1.5% to 7.5%, 2.5% to 5%, and any and all ranges and sub-ranges therebetween.

[0020] In some embodiments, the coating may also include a dispersing agent. In some embodiments, the dispersing agent may be at least one selected from the group consisting of polyvinylpyrrolidone (PVP), ethyl cellulose, polyethylene glycol, and mixtures thereof. In some embodiments, the dispersing agent has a weight percentage in the coating ranging from 0.01% to 5%. In some embodiments, the dispersing agent may be present in the coating at a weight percentage of 0.01% to 10%, 0.01% to 7.5%, 0.01% to 5%, 0.01% to 2.5%, 0.01% to 1%, 0.01% to 0.5%, 0.01% to 0.25%, 0.02% to 10%, 0.02% to 7.5%, 0.02% to 5%, 0.02% to 2.5%, 0.02% to 1%, 0.02% to 0.5%, 0.02% to 0.2 ... 0.05% to 10%, 0.05% to 7.5%, 0.05% to 5%, 0.05% to 2.5%, 0.05% to 1%, 0.05% to 0.5%, 0.05% to 0.25%, 0.1% to 10%, 0.1% to 7.5%, 0.1% to 5%, 0.1% to 2.5%, 0.1% to 1%, 0.1% to 0.5%, 0.1% to 0.25%, and any and all ranges and sub-ranges therebetween.

[0021] The present disclosure also provides compositions for preparing the coatings. The compositions may include a plurality of particles of element A, a plurality of particles of element B, a carbonaceous material, and a binder. In some embodiments, the compositions may also include a solvent and / or a dispersant. In some embodiments, the first and second plurality of particles of elements A and B, and the carbonaceous material are dispersed in a mixture including a solvent, a dispersant, and a binder.

[0022] In some embodiments, a coating can be prepared from the composition / mixture. The method can include (i) combining a plurality of particles of element A, a plurality of particles of element B, a carbonaceous material, a binder, a solvent, and a dispersant into a mixture, (ii) coating the mixture onto a substrate, and (iii) drying the mixture coated on the substrate to form a coating having particles of element A and element B distributed therein. In some embodiments, the method further includes calendering the coated substrate during or after drying the mixture coated on the substrate to smooth the surface of the coating.

[0023] In some embodiments, the mass ratio of solvent and dispersant to element A, element B, and binder in the mixture (ratio of (solvent + dispersant):(element A + element B + binder)) is in the range of 1:9 to 1:10.

[0024] In some embodiments, the mixture coated on the substrate is dried in air or an inert gas.

[0025] In some embodiments, the mixture coated on the substrate is dried at a temperature ranging from 80° C. to 130° C. for a period of 8 to 48 hours.

[0026] In some embodiments, the mixture coated on the substrate is further dried under vacuum at a temperature ranging from 60° C. to 120° C. for a period of 8 hours to 48 hours.

[0027] In one aspect, the present disclosure provides an electrochemical device, such as an all-solid-state battery, comprising a negative electrode having a coating described herein. The electrochemical device may comprise a positive electrode, a solid electrolyte, a coating, and a negative electrode, where the coating can function as an interfacial layer between the solid electrolyte and the negative electrode. In some embodiments, the negative electrode comprises a negative electrode current collector. In some embodiments, the negative electrode comprises a negative electrode active material layer comprising lithium metal and a negative electrode current collector.

[0028] In some embodiments, the solid electrolyte comprises an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or both.

[0029] In some embodiments, the oxide-based solid electrolyte is Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2、0≦y<3)、BaTiO3、Pb(Zr x Ti 1-x )O3(PZT, 0≦a≦1), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≦x<1, 0≦Y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2、0<y<3)、Li x Al y Ti z (PO4)3(0 <x<2、0<y<1、0<z<3)、Li 1+x+y (Al a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 (0≦x≦1, 0≦y≦1, 0≦a≦1, and 0≦b≦1), Li x La y TiO3(0 <x<2、0<y<3)、Li2O、LiOH、Li2CO3、LiAlO2、Li2O-Al2O3-Si2O-P2O5-TiO2-GeO2、Li 3+x La3M2O 12(M is at least one selected from the group consisting of Te, Nb, and Zr, and x is an integer from 1 to 10), and Li 3+x La3Zr 2-a M a O 12 (M is at least one selected from the group consisting of Ga, W, Nb, Ta, and Al, 0 < a < 2, and x is an integer from 1 to 10).

[0030] In some embodiments, the sulfide-based solid electrolyte is P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (each of m and n is a positive number, and Z is one selected from Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (each of p and q is a positive number, and M is one selected from P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (0 ≤ x ≤ 2) and is at least one selected therefrom.

[0031] In some embodiments, the positive electrode is LiFePO4, Li x MO2, Li x Ni 1-y-z Co y M1 z O2, and Li x Ni 1-y-z Mny M2 z O2, wherein M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements; and M1 is Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and 0.95≦x≦1.1, 1-yz>0, 0 <y≦0.5、0≦z≦0.5である。

[0032] In some embodiments, the electrochemical device exhibits at least 94% capacity retention after 20 cycles at a discharge rate of 0.33C.

[0033] In some embodiments, the electrochemical device exhibits a specific capacity of at least 160 mAh / g after 20 cycles at a discharge rate of 0.33C.

[0034] In some embodiments, the electrochemical device is a battery or a battery cell, hi some embodiments, the electrochemical device is an all-solid-state battery.

[0035] In some embodiments, cells with the anode coatings described herein can reduce the total cell resistance by 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, or 65% or more compared to that of a cell with Ag / C as the anode coating.

[0036] In some embodiments, cells with a negative electrode coating described herein can reduce charging overpotential by 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, or 70% or more compared to that of a cell with Ag / C as the negative electrode coating or protective layer at the same C-rate. In some embodiments, the C-rate is in the range of 5.5C to 6C, 5.5C to 7C, 5.5C to 8C, 5.5C to 9C, or 5.5C to 10C.

[0037] In some embodiments, the coating comprises Cu as element A and Zn as element B, with a Cu to Zn mass ratio of 3:7 and a Cu to Zn mass ratio relative to the carbonaceous material of 5:95, and the coating has a thickness of about 15-25 μm.

[0038] The present disclosure will be better understood by reference to the following Experimental Details; however, those skilled in the art will readily recognize that the specific experiments detailed are for illustrative purposes only and are not intended to limit the disclosure described herein, as defined by the claims that follow. [Example]

[0039] Preparation of the coated negative electrode

[0040] [Table 1]

[0041] Metal nanoparticles with particle sizes D50 of 40-60 nm and carbon black powder (D50 = 35 nm) were mixed in a mass ratio of 1:3 in N-methylpyrrolidone (NMP) (Sigma-Aldrich) containing 7% by mass of polyvinylidene fluoride (PVDF, Solef). The negative electrode slurry was prepared by slowly adding N-methylpyrrolidone to the mixture under constant stirring using a mixer (Thinky Corporation, AR-100).

[0042] The slurry was then coated onto a 10 μm-thick stainless steel foil using a bar coating method and dried in a convection oven at 80°C for 20 minutes. The resulting electrode was further dried under vacuum at 120°C for 12 hours. The average thickness of the coating layer was 15±2 μm. Anodes with coatings containing only carbon black were also prepared following the same mixing procedure, except that neither element A nor B was included. Table 1 summarizes the compositions of the various anode coatings.

[0043] Battery Assembly and Testing Batteries were assembled with the coated negative electrode, an NCA positive electrode with at least 80% positive electrode active material, and a silver germanite solid electrolyte. Cell testing was performed in two sequential steps. First, the rate capability was tested at a consistent charge rate of 0.1 C throughout the entire test, followed by sequential discharge rates of 0.33 C, 1 C, and 0.33 C. The specific capacity results are shown in Table 2 and Figure 3.

[0044] [Table 2]

[0045] Second, cycling performance was measured under continuous 0.33C / 0.33C conditions at 45°C. The voltage range given in these tests was 2.5V to 4.2V (vs. Li / Li). + ) during the entire test procedure. All of the cells were operated under 4 MPa. The specific capacity results for the Reference Example, Comparative Examples 1-3, and Examples 4 and 5 are shown in FIG. 4.

[0046] 3, Examples 1 to 3 had the same mass percentage of the carbonaceous material and the same total mass of elements A and B. Among Examples 1 to 3, Example 1 exhibited the highest specific capacity.

[0047] As shown in Figure 3, Examples 4 and 5 were comparable to the reference example (Ag / C) in terms of high-rate discharge capacity (1 C). Example 5 also matched the reference example not only in terms of capacity realization below 0.33 C, but also in capacity retention, which was well maintained up to 20 cycles. Without intending to be bound by any theory, this may be due to the uniform dispersion of Zn and Cu nanoparticles in the negative electrode, which are less likely to migrate toward the current collector compared to Ag nanoparticles. Figure 7 shows EIS results showing that Example 4 had a total cell resistance 50% lower than that of the Ag / C coating. The reduced cell resistance makes it easier for Li to migrate back and forth within the cell during cycling. In some embodiments, cells with the anode coatings described herein can reduce the total cell resistance by 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, or 65% or more compared to that of a cell with Ag / C as the anode coating.

[0048] 4, cells with the negative electrode coatings of the Reference Example, Comparative Example 3, Example 4, and Example 5 exhibit specific discharge capacities of 133, 152, 155, and 166 mAh / g, respectively, after 20 cycles at both a charge rate and a discharge rate of 0.33 C. In some embodiments, electrochemical devices with the negative electrode coatings disclosed herein exhibit higher specific capacities than electrochemical devices having an Ag / C nanocomposite as the negative electrode coating or carbon as the negative electrode coating. In some embodiments, electrochemical devices with the negative electrode coatings disclosed herein exhibit specific capacities that are 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 55% greater than the specific capacity of electrochemical devices having an Ag / C nanocomposite as the negative electrode coating. In some embodiments, electrochemical devices with the anode coatings disclosed herein exhibit a specific capacity that is 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% or 45% greater than the specific capacity of an electrochemical device having carbon as the anode coating.

[0049] As also shown in Figure 4, cells with the negative electrode coatings of the Reference Example, Comparative Example 3, Example 4, and Example 5 exhibit capacity retention of 74%, 86%, 92%, and 94%, respectively, after 20 cycles at both a 0.33C charge and discharge rate. In some embodiments, electrochemical devices with the negative electrode coatings disclosed herein exhibit higher capacity retention than electrochemical devices having an Ag / C nanocomposite as the negative electrode coating or carbon as the negative electrode coating. In some embodiments, electrochemical devices with the negative electrode coatings disclosed herein exhibit capacity retention that is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 55% greater than the capacity retention of electrochemical devices having an Ag / C nanocomposite as the negative electrode coating. In some embodiments, electrochemical devices with the negative electrode coatings disclosed herein exhibit a capacity retention that is 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% or 45% greater than the capacity retention of electrochemical devices having carbon as the negative electrode coating.

[0050] Based on the above data of Example 4, an electrochemical device can have a coating comprising Zn as element A, Cu as element B, and carbon black as the carbonaceous material in a mass ratio of 1.5:3.5:95, with a thickness ranging from 15 μm to 25 μm. In some embodiments, such an electrochemical device exhibits at least 90% capacity retention after 20 cycles at a charge / discharge rate of 0.33 C and / or exhibits a specific capacity of at least 155 mAh / g after 20 cycles at a charge / discharge rate of 0.33 C.

[0051] Also based on the above data of Example 5, an electrochemical device can have a coating comprising Zn as element A, Cu as element B, and carbon black as the carbonaceous material in a mass ratio of 3:7:90, with a thickness ranging from 15 μm to 25 μm. In some embodiments, such an electrochemical device exhibits at least 90% capacity retention after 20 cycles at a charge / discharge rate of 0.33 C and / or exhibits a specific capacity of at least 160 mAh / g after 20 cycles at a charge rate of 0.33 C.

[0052] These examples also demonstrate that agglomeration of element A in the coating, which can degrade the electrochemical performance of the battery, can be avoided. Figure 5 is a cross-sectional SEM image of the coating of the reference example, showing that some of the Ag nanoparticles (element A) are present as agglomerates. In contrast, Figure 6 is a cross-sectional SEM image of the coating of Example 4, which includes Zn as element A, Cu as element B, and a carbonaceous material, showing that the Zn and Cu nanoparticles have average particle sizes ranging from 20 nm to 80 nm and are uniformly distributed throughout the carbonaceous material. There are no agglomerates.

[0053] [Table 3]

[0054] As shown in Table 3, the cells with the Zn / Cu anode coating according to Example 5 exhibit significantly reduced overpotentials upon charging. Also shown in Figure 8, the cells with the anode coating according to Example 5 exhibit overpotentials of about -64 mV, about -127 mV, about -189 mV, about -310 mV, and about -334 mV for C-rates of 1 C, 2 C, 3 C, 5 C, and 5.5 C, respectively. However, the cells with the anode coating of the reference example exhibit overpotentials of about -160 mV, about -225 mV, about -330 mV, about -490 mV, and about -493 mV for C-rates of 1 C, 2 C, 3 C, 5 C, and 5.5 C, respectively. Compared to the reference example, the absolute values ​​of the charging overpotential of Example 5 are reduced by 60%, 46.7%, 42.7%, 36.7%, and 32.4% for C-rates of 1C, 2C, 3C, 5C, and 5.5C, respectively.

[0055] While the Ag / C reference example exhibited frequent micro-short circuit behavior, which can be indicated by a sudden increase in charge capacity followed by a decrease in coulombic efficiency, the cell with the Zn / Cu anode coating was very stable with cycling under 1 / 3C. This phenomenon is potentially due to the agglomeration and migration of Ag nanoparticles. In the case of the Zn / Cu anode, the active material content was optimized to minimize agglomeration, and the inactive material was uniformly dispersed without migration, which did not result in micro-short circuit behavior like the reference example.

[0056] Aspects In a first aspect, the present disclosure provides a coating comprising: ·Element A, which can be alloyed with lithium; Element B, which cannot be alloyed with lithium, and ·Carbonaceous materials, Including, The coating is provided wherein the carbonaceous material has a volume percentage of at least 50% in the coating.

[0057] In a second embodiment according to the first embodiment, the element A is a metal or a metalloid.

[0058] In a third embodiment according to the first or second embodiment, element A is capable of forming an alloy with lithium, the element lithium having a mass percentage of 4% or more in the alloy.

[0059] In a fourth embodiment according to any previous embodiment, the element A is at least one selected from the group consisting of Ag, Zn, Ti, Cd, Mg, Al, Ga, Si, Ge, In, Sn, Pb, Bi, and Sb.

[0060] In a fifth embodiment according to any previous embodiment, element A has a mass percentage in the coating ranging from 1% to 10%.

[0061] In a sixth embodiment according to any previous embodiment, element B has an electrical conductivity greater than the electrical conductivity of the carbonaceous material.

[0062] In a seventh embodiment according to any previous embodiment, the element B is at least one selected from the group consisting of Cu, Mo, Ir, W, Co, Ni, Ru, Fe, Se, Ta, Nb, V, and Zr.

[0063] In an eighth embodiment according to any previous embodiment, element B has a mass percentage in the coating ranging from 3% to 15%.

[0064] In a ninth embodiment according to any previous embodiment, the electrical conductivity of element B is greater than the electrical conductivity of element A.

[0065] In a tenth embodiment according to any previous embodiment, the mass ratio of element A to element B is in the range of 1:99 to 50:50.

[0066] In an eleventh embodiment according to any previous embodiment, the total mass percentage of element A and element B in the coating is in the range of 5% to 20%.

[0067] In a twelfth embodiment according to any previous embodiment, element A, element B or both are in the form of nanoparticles, nanoplatelets, nanowires or nanotubes in the coating.

[0068] In a thirteenth embodiment according to any previous embodiment, the nanoparticles have an average particle size (D50) in the range of 20 nm to 80 nm.

[0069] In a fourteenth embodiment according to the thirteenth embodiment, the nanoparticles do not include agglomerates in the cross section of the coating.

[0070] In a fifteenth embodiment according to any previous embodiment, the coating has a thickness in the range of 0.1 μm to 50 μm.

[0071] In a sixteenth embodiment according to any previous embodiment, the coating further comprises a binder.

[0072] In a seventeenth embodiment according to any previous embodiment, the coating further comprises a dispersant.

[0073] In an eighteenth aspect, the present disclosure provides a composition for preparing a coating according to the first aspect, the composition comprising: a first plurality of particles of element A; a second plurality of particles of element B, carbonaceous materials, and Binders, Includes.

[0074] In a nineteenth embodiment according to the eighteenth embodiment, the composition further comprises a solvent.

[0075] In a twentieth embodiment according to the eighteenth or nineteenth embodiment, the composition further comprises a dispersant.

[0076] In a twenty-first embodiment according to the nineteenth embodiment, the solvent is selected from the group consisting of N-methylpyrrolidone (NMP), tetrahydrofuran (THF), ethanol, distilled water, and mixtures thereof.

[0077] In a twenty-second embodiment according to the twentieth embodiment, the dispersant is at least one selected from the group consisting of polyvinylpyrrolidone (PVP), ethyl cellulose, polyethylene glycol, and mixtures thereof, and the dispersant has a mass percentage in the composition ranging from 0.01% to 5%.

[0078] In a 23rd embodiment according to any of the 18th to 22nd embodiments, the binder is at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride / hexafluoropropylene copolymer, polyimide, polyethylene, polyester, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose / styrene-butadiene rubber (CMC / SBR) copolymer, styrene butadiene rubber (SBR), and mixtures thereof, and the binder has a mass percentage in the composition ranging from 1% to 20%.

[0079] In a 24th aspect according to any of the 18th to 23rd aspects, the carbonaceous material is at least one selected from the group consisting of carbon fiber, carbon nanotube, carbon wire, natural graphite, artificial graphite, graphene, carbon black, acetylene black, ketjen black, and mixtures thereof.

[0080] In a twenty-fifth aspect, the present disclosure provides a method of preparing a coating, comprising: a) mixing a plurality of particles of element A, a plurality of particles of element B, a carbonaceous material, a binder, a solvent, and a dispersant into a mixture; b) coating the mixture onto a substrate; and c) drying the mixture coated on the substrate, thereby forming a coating having particles of element A and element B distributed therein; Including, A method is provided in which element A is capable of alloying with lithium and element B is not capable of alloying with lithium.

[0081] In a twenty-sixth embodiment according to the twenty-fifth embodiment, the method further comprises the step of calendering the coated substrate during or after drying the mixture coated on the substrate.

[0082] In a 27th embodiment according to the 25th or 26th embodiment, the mass ratio of the solvent and dispersant to the element A, element B and binder is in the range of 1:9 to 1:10.

[0083] In a twenty-eighth embodiment according to any of the twenty-fifth to twenty-seventh embodiments, the mixture coated on the substrate is dried in an inert gas.

[0084] In a twenty-ninth aspect, the present disclosure provides an electrochemical device comprising a coating according to any of the first to seventeenth aspects disposed on a negative electrode.

[0085] In a thirtieth embodiment according to the twenty-ninth embodiment, the negative electrode includes a negative electrode current collector.

[0086] In a thirty-first embodiment according to the twenty-ninth or thirtieth embodiment, the negative electrode comprises a layer of negative electrode active material comprising lithium metal.

[0087] In a thirty-second embodiment according to any of the twenty-ninth to thirty-first embodiments, the electrochemical device further comprises a solid electrolyte.

[0088] In a thirty-third aspect according to the thirty-second aspect, the solid electrolyte includes an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or both.

[0089] In the thirty-fourth aspect according to the thirty-second aspect, the oxide-based solid electrolyte is Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2、0≦y<3)、BaTiO3、Pb(Zr x Ti 1-x )O3(PZT, 0≦a≦1), Pb 1-x La xZr 1-y Ti y O3(PLZT)(0≦x<1, 0≦Y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3 - PbTiO3(PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0<x<2, 0<y<3), Li x Al y Ti z (PO4)3(0<x<2, 0<y<1, 0<z<3), Li 1+x+y (Al[[ID=2l]] a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 (0≦x≦1, 0≦y≦1, 0≦a≦l, and 0≦b≦1), Li x La y [[ID=A2]]TiO3(0<x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - Si2O - P2O5 - TiO2 - GeO2, Li 3+x La3M2O 12 (M is at least one selected from the group consisting of Te, Nb, and Zr, and x is an integer from 1 to 10), Li 3+x La3Zr[[ID=I49]] 2-a M a O 12 (M is at least one selected from Ga, W, Nb, Ta, and Al, 0<a<2, and x is an integer from 1 to 10), and is at least one selected from the group consisting of its mixtures.

[0090] It should be noted that there might be some tags that are not recognized in a common sense. If this is a specific format in a particular system, please provide more context for a more accurate translation. Also, some chemical formulas and notations are kept as they are as they are specific to the technical content and may not have a direct equivalent in a simple word - by - word translation.In a thirty-fifth aspect according to the thirty-third aspect, the sulfide-based solid electrolyte is P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (wherein m and n are each a positive number, and Z is one selected from Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (each of p and q is a positive number, and M is one selected from P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), Li 7-x PS 6-x I x At least one selected from (0≦x≦2).

[0091] In a thirty-sixth embodiment according to any of the twenty-ninth to thirty-fifth embodiments, the electrochemical device further comprises a positive electrode.

[0092] In a thirty-seventh embodiment according to the thirty-sixth embodiment, the positive electrode is LiFePO4, Li x MO2, Li x Ni 1-y-z Co y M1 z O2, and Li x Ni 1-y-z Mn y M2 zO2, wherein M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements; and M1 is Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and 0.95≦x≦1.1, 1-yz>0, 0 <y≦0.5、0≦z≦0.5である。

[0093] In a thirty-eighth embodiment according to any of the twenty-ninth to thirty-seventh embodiments, the electrochemical device exhibits at least 90% capacity retention after 20 cycles at a discharge rate of 0.33C.

[0094] In a thirty-ninth embodiment according to any of the twenty-ninth to thirty-eighth embodiments, the electrochemical device exhibits a specific capacity of at least 155 mAh / g after 20 cycles at a discharge rate of 0.33C.

[0095] In a 40th embodiment according to any of the 29th to 39th embodiments, the electrochemical device exhibits a charge overvoltage at a C-rate ranging from 1 C to 5.5 C that is at least 30% lower than the charge overvoltage of an electrochemical device comprising a negative electrode coating having an Ag / C layer at the same C-rate.

[0096] Various embodiments of features of the present disclosure are described herein. However, it should be understood that such embodiments are given by way of example only, and that numerous variations, modifications, and substitutions may occur to those skilled in the art without departing from the scope of the present disclosure. It should also be understood that various alternatives to the specific embodiments described herein are within the scope of the present disclosure. [Explanation of symbols]

[0097] 1. Coating 2 Particles of element A 3 Particles of element B 4 Carbonaceous materials 5 Negative electrode current collector 6 Negative electrode active material layer

Claims

1. A coating comprising: - an element A that can be alloyed with lithium, an element B that cannot be alloyed with lithium, and ・Carbonaceous materials, Including, A coating, wherein the carbonaceous material has a volume percentage of at least 50% in the coating, and the element A is a metal or a metalloid.

2. The coating of claim 1 , wherein said element A is capable of forming an alloy with lithium, and wherein elemental lithium has a mass percentage of 4% or greater in said alloy.

3. 2. The coating of claim 1, wherein the element A is at least one selected from the group consisting of Ag, Zn, Ti, Cd, Mg, Al, Ga, Si, Ge, In, Sn, Pb, Bi, and Sb.

4. 2. The coating of claim 1, wherein the element B has an electrical conductivity greater than that of the carbonaceous material and is at least one selected from the group consisting of Cu, Mo, Ir, W, Co, Ni, Ru, Fe, Se, Ta, Nb, V, and Zr.

5. 10. The coating of claim 1, wherein the element A has a weight percentage in the coating ranging from 1% to 10% and the element B has a weight percentage in the coating ranging from 3% to 15%.

6. The coating of claim 1 , wherein the total mass percentage of element A and element B in the coating ranges from 5% to 20%.

7. The coating of claim 1 , wherein the electrical conductivity of element B is greater than the electrical conductivity of element A.

8. The coating of claim 1 , wherein the mass ratio of element A to element B ranges from 1:99 to 50:

50.

9. 10. The coating of claim 1, wherein the element A, the element B, or both are in the form of nanoparticles, nanoplatelets, nanowires, or nanotubes in the coating.

10. 10. The coating of claim 9, wherein the nanoparticles are free of agglomerates in a cross section of the coating and have an average particle size (D50) in the range of 20 nm to 80 nm.

11. The coating of claim 1 , wherein the coating has a thickness in the range of 0.1 μm to 50 μm.

12. 1. A method for preparing a coating, comprising: a) mixing a plurality of particles of element A, a plurality of particles of element B, a carbonaceous material, a binder, a solvent, and a dispersant into a mixture; b) coating the mixture onto a substrate; c) calendering the coated substrate during or after drying the mixture coated on the substrate; and d) drying the mixture coated on the substrate, thereby forming a coating having particles of element A and element B distributed therein; Including, The method, wherein element A is capable of alloying with lithium and element B is not capable of alloying with lithium, and element A is a metal or a metalloid.

13. 13. The method of claim 12, wherein the dispersing agent comprises at least one selected from the group consisting of polyvinylpyrrolidone (PVP), ethyl cellulose, polyethylene glycol, and mixtures thereof, and the dispersing agent has a mass percentage in the mixture ranging from 0.01% to 5%.

14. 13. The method of claim 12, wherein the mass ratio of the solvent and the dispersant to the element A, the element B, and the binder is in the range of 1:9 to 1:

10.

15. 10. An electrochemical device comprising the coating of claim 1 disposed on a negative electrode.

16. 16. The electrochemical device of claim 15, wherein the negative electrode comprises a layer of negative electrode active material comprising lithium metal.

17. P ２ S ５ , Li ２ S-P ２ S ５ -LiX (X is a halogen element), Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ , Li ２ S-SiS ２ - LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ - LiI, Li ２ S-SiS ２ -P ２ S ５ - LiI, Li ２ S-B ２ S ３ , Li ２ S-P ２ S ５ -Z ｍ S ｎ (wherein m and n are each a positive number, and Z is one selected from Ge, Zn, and Ga), Li ２ S-GeS ２ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ２ S-SiS ２ -Li ｐ MO ｑ (each of p and q is a positive number, and M is one selected from P, Si, Ge, B, Al, Ga, and In), Li ７－ｘ P.S. ６－ｘ Cl ｘ (0≦x≦2), Li ７－ｘ P.S. ６－ｘ Br ｘ (0≦x≦2), Li ７－ｘ P.S. ６－ｘ I ｘ 16. The electrochemical device of claim 15, further comprising a sulfide-based solid electrolyte comprising at least one selected from the group consisting of: (0≦x≦2), and mixtures thereof.

18. 16. The electrochemical device of claim 15, wherein the electrochemical device exhibits at least 90% capacity retention after 20 cycles at a discharge rate of 0.33C.

19. 16. The electrochemical device of claim 15, wherein the electrochemical device exhibits a specific capacity of at least 155 mAh / g after 20 cycles at a discharge rate of 0.33 C.

20. 16. The electrochemical device of claim 15, wherein the electrochemical device exhibits a charging overvoltage at a C-rate ranging from 1 C to 5.5 C that is at least 30% lower than the charging overvoltage of an electrochemical device comprising a negative electrode coating having an Ag / C layer at the same C-rate.

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