The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery including the same, which enable the provision of an all-solid-state battery that exhibits excellent contact characteristics between the negative electrode and the solid electrolyte, along with improved lifespan characteristics.
background art
[4]
Secondary batteries have been mainly applied to small fields such as mobile devices and notebook computers, but recently, their application direction has been expanded to medium and large fields, mainly energy storage systems (ESS) or electric vehicles (EVs). ), etc., it is expanding into fields requiring high energy and high output. In the case of such a medium-large secondary battery, unlike a small-sized secondary battery, it is necessary to ensure safety with excellent performance and appropriate price because not only harsh operating environments such as temperature and shock, but also the use of more batteries. Since most of the currently commercialized secondary batteries use a liquid electrolyte in which lithium salt is dissolved in an organic solvent, they have potential risks of leakage, ignition, and explosion.
[5]
Therefore, in recent years, an all-solid-state battery has been developed. The all-solid-state battery is a battery using a solid electrolyte instead of the liquid electrolyte, and has a thermal energy compared to a conventional lithium secondary battery using a liquid electrolyte. It has the advantage of high stability. In addition, the all-solid-state battery is advantageous over conventional lithium secondary batteries in terms of high energy density and output characteristics, simplification of the manufacturing process and enlargement / compaction of the battery, so research and interest have been focused on this in recent years. there is.
[6]
On the other hand, in the case of conventional all-solid-state batteries, graphite negative electrodes were mainly used as in conventional lithium secondary batteries, but recently, in order to further improve the capacity characteristics of batteries, the use of lithium metal negative electrodes or negative electrodes using silicon-based active materials has been reviewed. and are being studied. As these lithium metal anodes and silicon-based anodes both have high theoretical capacities, high capacities and high energy densities can be realized.
[7]
However, when the lithium metal negative electrode is used, during the initial charging and discharging process of the battery, lithium moving from the positive electrode to the negative electrode is deposited on the surface of the negative electrode in the form of dendrites to form lithium dendrites, thereby improving the lifespan characteristics and stability of the battery. has the downside of lowering it. In addition, the silicon-based negative electrode also has a disadvantage in that a large volume change occurs during charging and discharging processes, and thus the lifespan characteristics of the battery are greatly deteriorated. Therefore, development of an anode and/or an all-solid-state battery with improved lifespan characteristics, etc., while enabling higher capacity and energy density, has been continuously requested.
[8]
In addition, since the all-solid-state battery includes a solid electrolyte, it is required to ensure sufficient contact characteristics between each electrode and the solid electrolyte to achieve high ionic conductivity in order to fully express the performance of the all-solid-state battery. However, due to the nature of the solid electrolyte, it is difficult to permeate into each electrode and it is not easy to secure a sufficient contact area, so all-solid-state batteries that have sufficient contact characteristics between the electrode and the solid electrolyte, low interfacial resistance, and high ionic conductivity are not yet available. Until now, it has not been properly developed.
[9]
Due to the problems of the prior art described above, there is a continuous demand for development of an all-solid-state battery-related technology that exhibits excellent contact characteristics between an electrode and a solid electrolyte as well as improved lifespan characteristics.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[10]
Accordingly, the present invention provides an all-solid-state battery negative electrode that enables the provision of an all-solid-state battery that exhibits improved lifespan characteristics and excellent contact characteristics between the negative electrode and the solid electrolyte while exhibiting high energy density.
[11]
The present invention also provides an all-solid-state battery exhibiting high energy density, improved lifespan characteristics, excellent contact characteristics between the negative electrode and the solid electrolyte, and low interfacial resistance, including the negative electrode.
means of solving the problem
[12]
Accordingly, the present invention is a crystalline carbon layer;
[13]
an amorphous carbon layer formed on the crystalline carbon layer, including a carbon defect structure formed of carbon atoms in an electron deficient state, and having nanoscale pores formed at the formation part of the carbon defect structure; and
[14]
It provides a negative electrode for an all-solid-state battery comprising a solid electrolyte material formed in the pores of the amorphous carbon layer.
[15]
The present invention also provides a positive electrode including a positive electrode current collector and a lithium composite oxide-based positive electrode active material layer formed on the positive electrode current collector;
[16]
The negative electrode of the present invention described above; and
[17]
An all-solid-state battery including an additional solid electrolyte layer interposed between a positive electrode and a negative electrode is provided.
Effects of the Invention
[18]
The negative electrode of the present invention excludes or minimally includes a separate active material layer formed three-dimensionally, such as a separate lithium metal thin film, and chemically treats the crystalline carbon layer to form carbon atoms in an electron deficient state. It includes a carbon defect structure and an amorphous carbon layer including a plurality of nanopores.
[19]
Due to the formation of the amorphous carbon layer including the carbon defect structure, an active material layer such as a lithium metal thin film formed in the form of an additional three-dimensional thin film in a battery to which an existing lithium metal anode is applied can be eliminated or reduced. Therefore, growth of lithium dendrites or the like from such a lithium metal thin film or the like can be fundamentally suppressed.
[20]
In addition, in the amorphous carbon layer, since a plurality of carbon atoms in an electron deficient state are included in the carbon defect structure, a plurality of lithium ions and/or a lithium compound containing the same may be inserted while donating electrons to the carbon atoms. there is. In addition, lithium metal may be uniformly electrodeposited around these lithium ions as nuclei. Accordingly, the amorphous carbon layer can induce uniform electrodeposition of lithium formed two-dimensionally on the same plane, and the electrodeposited lithium metal can act as an active material layer having a lithium ion source. Therefore, the negative electrode of the present invention can realize a high energy density corresponding to the case of applying a conventional lithium metal negative electrode.
[21]
In addition, since a solid electrolyte material can be filled in the nanopores formed in a large number of the amorphous carbon layer, a sufficient contact area between lithium metal serving as an anode and, furthermore, an active material layer, and the solid electrolyte filled in the nanopores is ensured. As a result, excellent contact properties between the negative electrode and the solid electrolyte, low interfacial resistance, and high ionic conductivity can be achieved.
[22]
As a result, when the negative electrode of the present invention is used, the formation of lithium dendrites is suppressed to show improved life characteristics, while having a high energy density comparable to the case of applying a lithium metal negative electrode, and sufficient contact characteristics between the negative electrode and the solid electrolyte. It becomes possible to provide a secured all-solid-state battery.
[23]
Such an all-solid-state battery can exhibit excellent cell performance and lifespan characteristics, and can be very preferably used as a next-generation battery applied to electric vehicles and the like.
Brief description of the drawing
[24]
1A and 1B show the results of analyzing the surface of each carbon layer by SEM and TEM, respectively, in the process of preparing the negative electrode of Comparative Example 1 and Example 1, before forming the solid electrolyte material.
[25]
2a to 2c show elemental analysis of carbon paper and a negative electrode by EDS in each manufacturing step of Example 1, and the analysis results are shown together with corresponding SEM pictures.
[26]
3 is a view showing the results of analyzing each carbon layer by XPS in a step before forming the solid electrolyte material during the manufacturing process of the negative electrode of Comparative Example 1 and Example 1.
[27]
4 is a view showing the results of Raman spectral analysis of each carbon layer in the step before forming the solid electrolyte material during the manufacturing process of the negative electrode of Comparative Example 1 and Example 1.
[28]
5 is a view showing the results of BET analysis of the surface of each carbon layer in a step before forming the solid electrolyte material during the manufacturing process of the negative electrode of Comparative Example 1 and Example 1.
[29]
6A to 6D show the results of analyzing the surface of the anode (front and back) after forming the solid electrolyte material in Example 1 and Comparative Example 1 by SEM, respectively.
[30]
7 is a graph showing the results of comparative evaluation of life characteristics of batteries of Comparative Examples 2 and 3 and Example 3.
Mode for Carrying Out the Invention
[31]
In the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated. As used throughout this specification, the terms "about," "substantially," and the like are used at or approximating that value when manufacturing and material tolerances inherent in the stated meaning are given, and do not convey the understanding of this application. Accurate or absolute figures are used to help prevent exploitation by unscrupulous infringers of the disclosed disclosure. The term "step of (doing)" or "step of" as used throughout the present specification does not mean "step for".
[32]
In this specification, the term "combination of these" included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of.
[33]
[34]
Based on the above definition, embodiments of the present invention will be described in detail. However, these are presented as examples, and thereby the present invention is not limited and the present invention is only defined by the scope of the claims to be described later.
[35]
Cathode for all-solid-state battery
[36]
According to one embodiment of the invention, a crystalline carbon layer;
[37]
It is formed on the crystalline carbon layer, and the electron grainan amorphous carbon layer including a carbon defect structure formed of carbon atoms in an electron deficient state, and having nanoscale pores formed in the formation portion of the carbon defect structure; and
[38]
An anode for an all-solid-state battery including a solid electrolyte material formed in pores of the amorphous carbon layer is provided.
[39]
As in the manufacturing method described below, the negative electrode of this embodiment is prepared by plasma oxidation treatment of the surface of a crystalline carbon fabric providing a crystalline carbon layer, surface coating of a metal organic framework (MOF) and carbonization thereof, and the like. It is prepared by proceeding to form the amorphous carbon layer, and forming a solid electrolyte material by applying a slurry coating method or the like on the amorphous carbon layer.
[40]
As a result of the chemical treatment of the crystalline carbon layer, a large number of carbon atoms in an electron deficient state are formed on the crystalline carbon layer, and a carbon defect structure including the carbon atoms in the electron deficient state is included. An amorphous carbon layer of a network structure may be formed.
[41]
In addition, in the amorphous carbon layer, as the metal organic framework is carbonized and decomposed, a plurality of nanopores having a size of 0.5 to 2 nm, 0.8 to 1.5 nm, or 1.0 to 1.2 nm may be formed in the formation part of the carbon defect structure. .
[42]
For reference, the amorphous nature of the amorphous carbon layer, the formation of a carbon defect structure (formation of carbon atoms in an electron deficient state), and the formation of a plurality of nanopores are determined by TEM analysis, XPS analysis, Raman spectrum analysis, BET analysis, etc. can be verified through
[43]
In the amorphous carbon layer, a plurality of carbon atoms in an electron deficient state are included, and a plurality of nanopores having a diameter of 0.5 to 2 nm, more specifically, 1.0 to 1.2 nm are formed. Therefore, electrons are donated from the conduction band of lithium, which serves to donate electrons to the carbon atoms, to the valence band of the carbon defect structure, resulting in a plurality of lithium ions and / or a lithium compound containing them (eg, Li Lithium in the form of a lithium carbide compound such as 3C 8 may be adsorbed, bonded, and intercalated to the electron-deficient carbon atoms. In addition, lithium ions inserted in this way act as a kind of nucleus, and lithium metal can be uniformly electrodeposited around the carbon defect structure centered on these lithium ions.
[44]
The lithium ions and the like and lithium metal electrodeposited around them may be intercalated and formed two-dimensionally in the plurality of nanopores, and may serve as a source of lithium ions for the anode. Accordingly, in the negative electrode of one embodiment, a lithium ion source may be included two-dimensionally on the same plane as (or inside) the amorphous carbon layer. Therefore, this amorphous carbon layer can act as an active material layer having a lithium ion source (lithium metal electrodeposited on the amorphous carbon layer) included in a two-dimensional plane by itself, and as a result, formed in the form of an additional three-dimensional thin film. Even if a lithium metal thin film or the like is not substantially added, a high energy density corresponding to the case of applying a conventional lithium metal anode can be implemented.
[45]
In addition, since a lithium ion source can be formed two-dimensionally in the carbon defect structure of the amorphous carbon layer without substantially adding a three-dimensional additional thin film of lithium metal, etc., a separate lithium metal additionally formed on the negative electrode Growth of lithium dendrites or the like from the thin film or the like can be fundamentally suppressed. As a result, the all-solid-state battery including the negative electrode of one embodiment can exhibit greatly improved lifespan characteristics and safety.
[46]
In addition, since a solid electrolyte material can be filled in the nanopores formed in the amorphous carbon layer, there is sufficient contact between the electrodeposited lithium metal serving as the negative electrode and, furthermore, the active material layer, and the solid electrolyte filled in the nanopores. area can be secured. Therefore, excellent contact properties between the negative electrode and the solid electrolyte, low interfacial resistance and high ionic conductivity can be achieved.
[47]
As a result, when the negative electrode of one embodiment is used, the formation of lithium dendrites is suppressed to exhibit improved life characteristics, while having a high energy density comparable to the case of applying a lithium metal negative electrode, and sufficient contact characteristics between the negative electrode and the solid electrolyte Provision of this secured all-solid-state battery becomes possible.
[48]
On the other hand, various characteristics of the amorphous carbon layer described above, for example, amorphousness, formation of a carbon defect structure (formation of carbon atoms in an electron deficient state), and formation of a plurality of nanopores, the cathode surface, for example, amorphous For the carbon layer, it can be confirmed by performing TEM analysis, XPS analysis, Raman spectrum analysis, BET analysis, and the like.
[49]
First, it can be confirmed that the amorphous carbon layer is formed of disordered and amorphous carbon atoms through a result of TEM analysis. In addition, through these TEM images, it can be confirmed that it is formed in the form of a plurality of graphene layers having a thickness of about 1 to 100 nm, or about 2 to 70 nm, and formed in the form of a layer having a plurality of defects (defective layer) can confirm that it has been done.
[50]
In addition, when the amorphous carbon layer was analyzed by XPS, it was confirmed that a large number of nanopores were formed due to the carbonization and decomposition process after the formation of the metal organic framework in the manufacturing process. In addition, the XPS analysis From the results, a separate peak originating from the carbon defect structure including the electron-deficient carbon atoms, eg, the nanopores, can be identified. In particular, the ratio of separate peaks derived from such a carbon defect structure/peaks derived from carbon having an sp 2 orbital hybridization structure (normal carbon having no electron deficient state) is 0.3 or more, or 0.35 to 0.50, or 0.4 to 0.45 , it can be confirmed that a significant proportion of carbon atoms in an electron-deficient state and carbon defect structures including them were formed at a high density.
[51]
In addition, through the results of Raman spectrum analysis of the amorphous carbon layer, the peak (D band; electron deficient state of the carbon defect structure) of 1500 cm -1 or less, or 1100 to 1500 cm -1 derived from the carbon defect structure It can be confirmed that the peak (G band; peak derived from normal carbon having a Graphitic structure) exhibits an intensity greater than 1500 cm -1 and less than or equal to 2000 cm -1 . More specifically, the intensity ratio defined by the peak of the D band / the peak of the P band is 1 or more, or 1 to 1.5. or 1.1 to 1.3.
[52]
Even through these Raman spectral analysis results, it can be confirmed that carbon atoms in an electron-deficient state and carbon defect structures including them are formed at a high density on the amorphous carbon layer included in the negative electrode of one embodiment at a considerable rate.
[53]
In addition, in the Raman spectrum of the amorphous carbon layer, additional broad peaks may be identified in the range of 2500 cm -1 or more, or 2500 to 2900 cm -1 , or 2600 to 2800 cm -1 . From this, it can be confirmed that the amorphous carbon layer may have a form including a plurality of carbon layers.
[54]
In addition, the formation of a plurality of nanopores included in the amorphous carbon layer can also be confirmed through BET surface analysis using nitrogen adsorption, and specific analysis results thereof are also described in test examples to be described later.
[55]
As described above, since the carbon defect structure including a plurality of nanopores and carbon atoms in an electron deficient state is formed at a high density in the amorphous carbon layer, lithium ions and/or A lithium compound may be two-dimensionally intercalated, and lithium metal electrodeposited around such lithium ions may be two-dimensionally included on the amorphous carbon layer. The lithium ion and the like, and lithium metal may act as a lithium ion source for the negative electrode.
[56]
As a result, without substantially applying a lithium metal thin film additionally formed in the form of a three-dimensional thin film on the anode, the amorphous carbon layer is formed by itself, including a high-density lithium ion source formed two-dimensionally therein. It can act as an active material layer. Therefore, the all-solid-state battery including the negative electrode of one embodiment may exhibit high capacity and high energy characteristics that are comparable to or higher than those of conventional lithium metal negative electrode batteries. Furthermore, since problems such as three-dimensional growth of lithium dendrites to the outside of the electrode from the lithium metal thin film formed in the form of a separate thin film can also be fundamentally suppressed, the all-solid-state battery including the negative electrode of one embodiment has a greatly improved lifespan characteristics and safety.
[57]
Meanwhile, in the negative electrode of the above-described embodiment, a solid electrolyte material is included in the nanopores of the amorphous carbon layer. As such a solid electrolyte material is included in a plurality of nanopores on the negative electrode, the solid electrolyte may have a large contact area with the negative electrode and lithium metal acting as an active material layer. Accordingly, an all-solid-state battery including the negative electrode of one embodiment may exhibit sufficient contact characteristics between the negative electrode and the solid electrolyte, low interfacial resistance, and high ionic conductivity.
[58]
Such a solid electrolyte material may be formed, for example, by coating and drying a slurry composition including a solid electrolyte, a binder, and a solvent on the amorphous carbon layer, and as a result, it may be impregnated into the nanopores. there is. In addition, in the negative electrode finally formed by this method, the solid electrolyte material present in the nanopores may include a solid electrolyte and a binder.
[59]
The type of the solid electrolyte is not particularly limited, and any solid electrolyte previously known to be usable in an all-solid-state battery, for example, an oxideAny of a sulfide-based, polymer-based, or the like solid electrolyte may be used without particular limitation. However, a sulfide-based solid electrolyte may be appropriately used in consideration of the slurry coating processability and high ionic conductivity of the solid electrolyte material.

WE CLAIM:

[Claim 1]
crystalline carbon layer; an amorphous carbon layer formed on the crystalline carbon layer, including a carbon defect structure formed of carbon atoms in an electron deficient state, and having nanoscale pores formed in the formation portion of the carbon defect structure; and a solid electrolyte material formed in the pores of the amorphous carbon layer.
[Claim 2]
The negative electrode for an all-solid-state battery according to claim 1, wherein the solid electrolyte material includes a sulfide solid electrolyte and a binder.
[Claim 3]
The negative electrode for an all-solid-state battery according to claim 2, wherein the sulfide solid electrolyte comprises a sulfide-based compound of Formula 1: [Formula 1] M 1 aM 2 bS cX 1 d In Formula 1, M 1 is an alkali metal and an alkali At least one selected from earth metals, M 2 is Sb, Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Bi, Ti, V, Cr, Mn, Fe , Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W or La, and X 1 is F, Cl, Br, I, Se, Te or O , and 0