Silicon-based composite anode active material for secondary battery and anode including the same

Abstract

The present invention provides a silicon-based composite anode active material for a secondary battery and an anode including the silicon-based composite anode active material. The anode active material of the secondary battery may be a silicon-based composite anode active material, which may include a graphite and a silicon component, and the silicon component includes two or more selected from Si, Si-M, SiOx, and SiC. Si-M may be a silicon alloy, and M may include at least one selected from transition metals, alkaline earth metals, Group 13 elements, Group 14 elements, and rare earth elements.

Description

Technical Field

[0001] The present invention relates to an anode active material for a secondary battery (e.g., a silicon-based composite anode active material) and an anode including the anode active material. Background Art

[0002] To reduce environmental pollution, in addition to using fossil fuels, the automotive industry has diversified by using electric energy. For example, lithium secondary batteries have been most commonly used as a source of electric energy in vehicles. In recent years, battery energy densification has been the most important issue for increasing the vehicle mileage. Therefore, to achieve this purpose, it is necessary to increase the energy density of the materials used.

[0003] Although batteries using Ni-Co-Mn-based or Ni-Co-Al-based cathode materials and graphite anodes have been developed, due to limitations in energy density, materials capable of replacing these materials have been developed. For example, silicon can provide an energy density much greater than that of conventional graphite (360 mAh / g), e.g., a capacity exceeding 4000 mAh / g.

[0004] However, when using a silicon anode, volume expansion may occur during the charge / discharge process, resulting in a volume expansion of about four times that of the conventional case when charged to Li4.4Si. Therefore, electrode tearing and cracks may occur, which is not conducive to the life and safety of the electrode. In addition, a large irreversible capacity may be generated when lithium ions are consumed during the initial charge. Summary of the Invention

[0005] In a preferred aspect, there is provided an anode active material for a secondary battery (e.g., a silicon-based composite anode active material) and an anode including the anode active material. Compared with conventional silicon anode materials, by controlling the composition (e.g., silicon component) of silicon anode materials having different characteristics, the anode active material can have excellent life characteristics and volume expansion suppression ability while maintaining a high energy density.

[0006] In one aspect, there is provided an anode active material for a secondary battery (e.g., a silicon-based composite anode active material). The anode active material (e.g., a silicon-based composite anode active material) may include graphite and a silicon component.

[0007] As used herein, the silicon component refers to a compound or material including silicon (Si) as a main component, and the silicon may exist in the form of elemental Si, silicon metal (Si-M, e.g., silicon alloy), silicon oxide (SiO x ) or silicon carbide (SiC). The silicon component may suitably include those selected from Si, Si-M, SiO xand two or more of SiC. Si-M can be a silicon alloy, and M can suitably include one or more selected from transition metals, alkaline earth metals, Group 13 elements, Group 14 elements, and rare earth elements.

[0008] The anode active material can suitably include: a silicon component and the remaining graphite, the silicon component including two selected from an amount of Si-M greater than 0 wt% and about 5 wt% or less, an amount of SiO greater than 0 wt% and about 11 wt% or less x and an amount of SiC greater than 0 wt% and 20 wt% or less. All wt% herein are based on the total weight of the anode active material.

[0009] The term "wt%" can be used equivalently with "% by weight", and both "wt%" and "% by weight" should be based on the total weight of the composition, such as the total weight of the anode active material.

[0010] In addition, the anode active material can suitably include: a silicon component and the remaining graphite, the silicon component including two selected from an amount of Si-M greater than 0 wt% and about 9 wt% or less, an amount of SiO greater than 0 wt% and about 11 wt% or less x and an amount of SiC greater than 0 wt% and about 35 wt% or less.

[0011] Alternatively, the anode active material can suitably include: a silicon component and the remaining graphite, the silicon component including an amount of Si-M greater than 0 wt% and about 11 wt% or less and an amount of SiC greater than 0 wt% and about 35 wt% or less.

[0012] In addition, the anode active material can suitably include: a silicon component and the remaining graphite, the silicon component including two selected from an amount of Si-M greater than 0 wt% and about 20 wt% or less, an amount of SiO greater than 0 wt% and about 20 wt% or less x and an amount of SiC greater than 0 wt% and about 60 wt% or less.

[0013] The graphite can suitably include natural graphite, artificial graphite, or a combination thereof.

[0014] M can suitably include one or more selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, and Po.

[0015] In one aspect, an anode (e.g., a silicon-based composite anode) of a secondary battery is provided. The anode (e.g., a silicon-based composite anode) may include an anode active material (e.g., a silicon-based composite anode active material) and a conductive material, the anode active material including graphite and a silicon component, the silicon component including two or more selected from Si, Si-M, SiO x and SiC. Si-M may be a silicon alloy, and M may suitably include one or more selected from transition metals, alkaline earth metals, group 13 elements, group 14 elements, and rare earth elements.

[0016] The conductive material may suitably include one or more selected from graphite, carbon black, CNT (carbon nanotube), graphene, and graphene oxide.

[0017] As described above, the anode active material may suitably include: a silicon component and the remaining graphite, the silicon component including two of Si-M in an amount greater than 0 wt% and about 5 wt% or less, SiO in an amount greater than 0 wt% and about 11 wt% or less, x and SiC in an amount greater than 0 wt% and about 20 wt% or less, all wt% being based on the total weight of the anode active material.

[0018] In addition, the anode active material may suitably include: a silicon component and the remaining graphite, the silicon component including two of Si-M in an amount greater than 0 wt% and about 9 wt% or less, SiO in an amount greater than 0 wt% and about 11 wt% or less, x and SiC in an amount greater than 0 wt% and 35 wt% or less, all wt% being based on the total weight of the anode active material.

[0019] Alternatively, the anode active material may suitably include: a silicon component and the remaining graphite, the silicon component including Si-M in an amount greater than 0 wt% and about 11 wt% or less and SiC in an amount greater than 0 wt% and about 35 wt% or less, all wt% being based on the total weight of the anode active material.

[0020] In addition, the anode active material may suitably include: a silicon component and the remaining graphite, the silicon component including two of Si-M in an amount greater than 0 wt% and about 20 wt% or less, SiO in an amount greater than 0 wt% and about 20 wt% or less, x and SiC in an amount greater than 0 wt% and about 60 wt% or less, all wt% being based on the total weight of the anode active material.

[0021] The graphite may suitably include natural graphite, artificial graphite, or a combination thereof.

[0022] M may suitably include one or more selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, and Po.

[0023] A secondary battery including the anode described herein is further provided.

[0024] A vehicle including the secondary battery as described herein is also provided.

[0025] Compared with a conventional silicon anode, according to various exemplary embodiments of the present invention, excellent life characteristics and volume expansion suppression ability can be ensured while having a high energy density. Moreover, compared with compositions of the same capacity, as the amount of graphite used as a base material increases, the durability is improved and the price can be reduced.

[0026] Other aspects of the present invention are disclosed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a graph comparing the life characteristics of Example 1 and 2 and Comparative Examples 1 to 5 according to an exemplary embodiment of the present invention.

[0028] Figure 2 It is a graph comparing the life characteristics of Examples 3 to 5 and Comparative Examples 1, 6, and 7 according to an exemplary embodiment of the present invention.

[0029] Figure 3 It is a graph comparing the life characteristics of Example 6 and Comparative Examples 1 and 8 according to an exemplary embodiment of the present invention.

[0030] Figure 4 It is a graph comparing the life characteristics of Examples 7 to 9 and Comparative Examples 1, 9, and 10 according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0031] The anode active material (e.g., a silicon-based composite anode active material) of a secondary battery according to an embodiment of the present invention may include i) graphite and ii) a silicon component including two or more selected from Si, Si-M, SiO x and SiC. Si-M may preferably be a silicon alloy, and M may suitably include one or more selected from transition metals, alkaline earth metals, Group 13 elements, Group 14 elements, and rare earth elements.

[0032] Exemplary embodiments of the present invention will be described below. However, the embodiments of the present invention can be modified into various other forms, and the technical concept of the present invention is not limited to the embodiments described below. Moreover, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

[0033] The terms used in the present invention are only for explaining specific embodiments. Therefore, for example, unless the context clearly indicates otherwise, singular expressions include plural expressions. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are also intended to include the plural forms.

[0034] Terms such as "comprising" or "having" used in the present invention are specifically used to indicate the presence of the described features, steps, functions, elements, or combinations thereof, etc., and cannot be used to pre-exclude the presence of elements, steps, functions, components, or combinations thereof.

[0035] Unless otherwise defined, all terms used herein should be interpreted as having the same meaning as commonly understood by those skilled in the art to which the present invention pertains. Therefore, unless clearly stated herein, certain terms should not be interpreted as having overly imaginative or formal meanings.

[0036] It should also be understood that terms such as "about" and "substantially" used in this specification when used in or near numerical values are mentioned when expressing the errors allowed by inherent manufacturing and materials, and are used to prevent unscrupulous people from unreasonably using the exact numbers or absolute numbers disclosed in the present invention to help understand the present invention. Unless specifically stated or obvious from the context, the term "about" used herein is understood to be within the normal tolerances in the art, for example within 2 average standard deviations. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the specified value. Unless obvious from the context, all numerical values provided herein are modified by the term "about".

[0037] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally include motor vehicles, such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, vessels including various boats and ships, and aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum energy sources). As mentioned herein, a hybrid vehicle is a vehicle having two or more power sources, such as a vehicle having both gasoline power and electric power.

[0038] In the related art, conventional silicon anodes may cause a huge problem of volume expansion during charging / discharging, resulting in a volume expansion of about 4 times that of the conventional case when charged to Li4.4Si. Therefore, electrode tearing and cracks may occur, which is not conducive to electrode life and safety factors. In addition, when consuming lithium ions during initial charging, a large irreversible capacity may be generated.

[0039] To solve the above problems, the present invention provides an anode active material for a secondary battery (for example, a silicon-based composite anode active material) and an anode including the anode active material. Compared with conventional silicon anodes, by controlling the composition of silicon anode materials with different characteristics, the anode active material or the silicon-based composite anode active material can provide excellent life characteristics and volume expansion suppression ability while maintaining a high energy density.

[0040] The silicon-based composite anode active material of the secondary battery according to an exemplary embodiment of the present invention may include graphite and at least two selected from Si, Si-M, SiO x and SiC, where Si-M is a silicon alloy, and M includes at least one selected from transition metals, alkaline earth metals, group 13 elements, group 14 elements, and rare earth elements. Hereinafter, the silicon alloy will be simply referred to as Si-M.

[0041] In addition, in one embodiment, M may include at least one selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0042] The present invention may include graphite and more than two selected from Si, Si-M, SiO x and SiC having different characteristics. Thus, it is possible to ensure a silicon-based composite anode active material for a secondary battery having a high energy density, excellent life characteristics, and volume expansion suppression ability and an anode including the silicon-based composite anode active material.

[0043] In addition, according to the present invention, the respective composition ratios of graphite and Si, Si-M, SiO x and SiC having different characteristics can be controlled. In addition, when including more than two selected from Si, Si-M, SiO x and SiC, only the respective advantages of Si, Si-M, SiO x and SiC can be exhibited.

[0044] For example, when Si-M is added to the anode active material or the anode active material contains Si-M, the discharge efficiency can be improved, but the life characteristics may be reduced.

[0045] For example, when SiO is added to the anode active material x or the anode active material contains SiO x the life characteristics can be improved, but the discharge efficiency may be reduced.

[0046] For example, when SiC is added to the anode active material or the anode active material contains SiC, the volume expansion suppression ability can be ensured, and the discharge efficiency can be improved. However, compared with the case of adding Si-M, the life characteristics may not be sufficiently improved.

[0047] For example, when graphite is added, the durability can be improved.

[0048] In addition, when listing each of the above components in order from the silicon component with the highest energy density, it can be listed as Si-M, SiO x , SiC, and graphite. In addition, as the silicon content decreases, the price can be reduced, and the volume expansion suppression ability can be improved, thereby obtaining excellent battery life characteristics.

[0049] According to various exemplary embodiments of the present invention, desired battery characteristics can be obtained by controlling the respective composition ratios of the above components.

[0050] For example, the composition ratio for obtaining a discharge capacity of about 410 mAh / g may include: a silicon component and the remaining graphite, the silicon component including two selected from an amount of Si-M greater than 0 wt% and about 5 wt% or less, an amount of SiO greater than 0 wt% and about 11 wt% or less x and an amount of SiC greater than 0 wt% and about 20 wt% or less. All weight percentages are based on the total weight of the anode active material. In the above composition, a discharge efficiency of about 92.0% or higher, a life characteristic of about 93.5% or higher (0.5C, 30th cycle), and an expansion rate of about 28.0% or lower (after the first cycle charge) can be ensured.

[0051] For example, the composition for obtaining a discharge capacity of about 430 mAh / g may include: a silicon component and the remaining graphite, the silicon component including an amount of Si-M greater than 0 wt% and about 9 wt% or less, an amount of SiO greater than 0 wt% and about 11 wt% or less xTwo of SiC in an amount greater than 0 wt% and about 35 wt% or less. All wt% are based on the total weight of the anode active material. In the above composition, a discharge efficiency of about 88.0% or higher, a life characteristic of about 93.5% or higher (0.5C, 30th cycle), and a swelling rate of about 28.0% or lower (after the first cycle charge) can be ensured.

[0052] For example, a composition that obtains a discharge capacity of about 450 mAh / g may include: a silicon component and the remaining graphite, the silicon component including Si-M in an amount greater than 0 wt% and about 11 wt% or less and SiC in an amount greater than 0 wt% and about 35 wt% or less. All wt% are based on the total weight of the anode active material. In the above composition, a discharge efficiency of about 91.0% or higher, a life characteristic of about 95.8% or higher (0.5C, 30th cycle), and a swelling rate of about 28.0% or lower (after the first cycle charge) can be ensured.

[0053] For example, a composition that obtains a discharge capacity of about 550 mAh / g may include: a silicon component and the remaining graphite, the silicon component including two selected from Si-M in an amount greater than 0 wt% and about 20 wt% or less, SiO x and SiC in an amount greater than 0 wt% and about 60 wt% or less. All wt% are based on the total weight of the anode active material. In the above composition, a discharge efficiency of about 80.3% or higher, a life characteristic of about 87.3% or higher (0.5C, 30th cycle), and a swelling rate of about 41.7% or lower (after the first cycle charge) can be ensured.

[0054] Although embodiments of the present invention have been described above, the concept of the present invention is not limited to the above embodiments and can be changed in various ways within the scope understandable by those skilled in the art.

[0055] In the silicon-based composite anode active material according to an exemplary embodiment of the present invention, the graphite may suitably include natural graphite, artificial graphite, or a combination thereof.

[0056] The anode (e.g., a silicon-based composite anode) of a secondary battery according to an exemplary embodiment of the present invention may suitably include a silicon-based composite anode active material and a conductive material, the silicon-based composite anode active material including graphite and a silicon component, the silicon component including two or more selected from Si, Si-M, SiO x and SiC. Si-M may be a silicon alloy, and M suitably includes one or more selected from transition metals, alkaline earth metals, group 13 elements, group 14 elements, and rare earth elements.

[0057] In the following, descriptions of the silicon-based composite anode active material that are the same as those described above will be omitted.

[0058] According to an exemplary embodiment of the present invention, the conductive material may suitably include one selected from graphite, carbon black, CNT (carbon nanotube), graphene, and graphene oxide.

[0059] Compared with a conventional silicon anode, the anode active material (e.g., silicon-based composite anode active material) of a secondary battery according to various exemplary embodiments of the present invention and an anode (e.g., silicon-based composite anode) including the anode active material may have a high energy density, excellent life characteristics, and volume expansion suppression ability.

[0060] In addition, compared with a composition of the same capacity, as the amount of graphite used as a base material increases, the durability is improved and the price can be reduced.

[0061] The present invention will be described more specifically below by way of examples. However, it should be noted that the following examples are intended to illustrate the present invention in more detail and do not limit the scope of the present invention. The scope of the present invention is determined by the matters listed in the claims and matters reasonably inferred therefrom.

[0062] Examples

[0063] The manufacturing processes of each example and each comparative example are briefly described below, and then each example and each comparative example are compared and evaluated with reference to the drawings.

[0064] Preparation of Example 1

[0065] An anode active material was prepared by dry-mixing 2 wt% of Si-M, 20 wt% of SiC, and the remaining natural graphite. Then, a slurry was prepared in an aqueous solution system using 92 wt% of the silicon-based composite anode active material, 3 wt% of graphite conductive material, 3 wt% of CMC / SBR (as a binder), and 2 wt% of acrylic binder, and then an anode was prepared. Subsequently, a secondary battery using the anode prepared above was prepared.

[0066] Preparation of Example 2

[0067] A secondary battery of Invention Example 2 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 2 wt% of Si-M, 20 wt% of SiC, and the remaining artificial graphite.

[0068] Preparation of Example 3

[0069] The secondary battery of Invention Example 3 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 3 wt% of Si-M, 27 wt% of SiC, and the balance of natural graphite.

[0070] Preparation of Example 4

[0071] The secondary battery of Invention Example 4 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 3 wt% of Si-M, 27 wt% of SiC, and the balance of artificial graphite.

[0072] Preparation of Example 5

[0073] The secondary battery of Invention Example 5 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 2 wt% of Si-M, 10 wt% of SiO x and the balance of natural graphite.

[0074] Preparation of Example 6

[0075] The secondary battery of Invention Example 6 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 7 wt% of Si-M, 23 wt% of SiC, and the balance of natural graphite.

[0076] Preparation of Example 7

[0077] The secondary battery of Invention Example 7 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 12 wt% of Si-M, 60 wt% of SiC, and the balance of natural graphite.

[0078] Preparation of Example 8

[0079] The secondary battery of Invention Example 8 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 10 wt% of Si-M, 20 wt% of SiO x and the balance of natural graphite.

[0080] Preparation of Example 9

[0081] The secondary battery of Invention Example 9 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 55 wt% of SiC, 20 wt% of SiO x and the balance of natural graphite.

[0082] Preparation of Comparative Example 1

[0083] The secondary battery of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the anode active material was prepared only by dry-mixing graphite.

[0084] Preparation of Comparative Example 2

[0085] The secondary battery of Comparative Example 2 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 5 wt% of Si-M and the remaining natural graphite.

[0086] Preparation of Comparative Example 3

[0087] The secondary battery of Comparative Example 3 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 5 wt% of Si-M and the remaining artificial graphite.

[0088] Preparation of Comparative Example 4

[0089] The secondary battery of Comparative Example 4 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 5 wt% of Si-M, 28 wt% of artificial graphite, and the remaining natural graphite.

[0090] Preparation of Comparative Example 5

[0091] The secondary battery of Comparative Example 5 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 35 wt% of SiC and the remaining natural graphite.

[0092] Preparation of Comparative Example 6

[0093] The secondary battery of Comparative Example 6 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 8 wt% of Si-M and the remaining natural graphite.

[0094] Preparation of Comparative Example 7

[0095] The secondary battery of Comparative Example 7 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 11 wt% of SiO x and the remaining natural graphite.

[0096] Preparation of Comparative Example 8

[0097] The secondary battery of Comparative Example 8 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 10 wt% of Si-M and the remaining natural graphite.

[0098] Preparation of Comparative Example 9

[0099] A secondary battery of Comparative Example 9 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 20% by weight of Si-M and the remaining natural graphite.

[0100] Preparation of Comparative Example 10

[0101] A secondary battery of Comparative Example 10 was manufactured in the same manner as in Example 1, except that the anode active material was prepared by dry-mixing 85% by weight of SiC and the remaining natural graphite.

[0102] Evaluation

[0103] In this specification, anode active materials were prepared by controlling the composition based on the discharge capacity, and thus Examples and Comparative Examples were prepared. Below, the battery characteristics of each Example and each Comparative Example were evaluated based on the discharge capacity.

[0104] (1) Discharge capacity of 410 mAh / g

[0105] Table 1 below shows the discharge capacity (mAh / g), discharge efficiency (%), life characteristics (0.5C, 30th cycle), and swelling rate (after the first cycle charge) of Comparative Examples 1 to 5 and Examples 1 and 2, in which the composition ratio was controlled to have a discharge capacity of about 410 mAh / g. In Table 1, the life characteristics (0.5C) were values obtained by measuring the ratio (%) of the discharge capacity at the 30th cycle to the initial discharge capacity in each Comparative Example and each Example.

[0106] Figure 1 is a graph comparing the life characteristics of Examples 1 and 2 and Comparative Examples 1 to 5, and it is a graph showing the change in discharge capacity with the number of cycles.

[0107] Table 1

[0108]

[0109] Below, each Example and each Comparative Example will be comparatively evaluated with reference to Table 1 and Figure 1 Comparatively evaluate each Example and each Comparative Example.

[0110] As shown in Table 1, the discharge capacities of Examples 1 and 2 were 408.5 mAh / g and 393.6 mAh / g, respectively, indicating a sufficient discharge capacity of about 410 mAh / g. At the same time, a discharge efficiency of 92.0% or higher, life characteristics (0.5C, 30th cycle) of 93.5% or higher, and a swelling rate (after the first cycle charge) of 28.0% or lower could be ensured.

[0111] On the other hand, in the case of Comparative Example 1 using only graphite, a discharge capacity of 410 mAh / g could not be obtained, but a low discharge capacity of 360 mAh / g was obtained.

[0112] In the case of Comparative Example 2, it can be seen that the discharge efficiency is lower than that of Examples 1 and 2.

[0113] In the case of Comparative Examples 3, 4, and 5, it can be seen that, compared with Examples 1 and 2, the discharge efficiency is lower, the life characteristics are lower, and the expansion rate is larger.

[0114] In particular, referring to Figure 1 , in the case of Examples 1 and 2, compared with the start, the discharge capacity does not change significantly with the number of cycles, and it can be seen that the discharge capacity remains stable compared with Comparative Examples 1 to 5.

[0115] As described above, it can be seen that, considering the life characteristics, expansion ratio, and discharge efficiency, the optimal composition of the silicon-based composite anode active material that ensures a discharge capacity of 410 mAh / g is as follows: a silicon component and the remaining graphite. Based on the total weight of the anode active material, the silicon component includes two selected from an amount of Si-M greater than 0 wt% and 5 wt% or less, an amount of SiO greater than 0 wt% and about 11 wt% or less, and an amount of SiC greater than 0 wt% and 20 wt% or less. x and two selected from an amount of SiC greater than 0 wt% and 20 wt% or less.

[0116] (2) Discharge capacity of 430 mAh / g

[0117] Table 2 below shows the discharge capacity (mAh / g), discharge efficiency (%), life characteristics (0.5C, 30th cycle), and expansion rate (after the first cycle charge) of Comparative Examples 1, 6, and 7 and Examples 3 to 5 that control the composition ratio to have a discharge capacity of about 430 mAh / g. In Table 2, the life characteristics (0.5C) are values obtained by measuring the ratio (%) of the discharge capacity at the 30th cycle to the initial discharge capacity in each comparative example and each example.

[0118] Figure 2 is a graph comparing the life characteristics of Examples 3 to 5 and Comparative Examples 1, 6, and 7, and it is a graph showing the change in discharge capacity with the number of cycles.

[0119] Table 2

[0120]

[0121] Each example and each comparative example will be comparatively evaluated below with reference to Table 2 and Figure 2 comparatively evaluate each example and each comparative example.

[0122] As shown in Table 2, the discharge capacities of Examples 3 to 5 were 423.1 mAh / g, 425.8 mAh / g, and 421.6 mAh / g, respectively, indicating a sufficient discharge capacity greater than about 430 mAh / g. At the same time, a discharge efficiency of 88.0% or higher, a life characteristic of 93.5% or higher (0.5C, 30th cycle), and a swelling rate of 28.0% or lower (after the first cycle charge) were obtained.

[0123] On the other hand, in the case of Comparative Example 1, a discharge capacity of 430 mAh / g could not be obtained using only graphite, but a low discharge capacity of 360 mAh / g was obtained.

[0124] In the case of Comparative Example 6, it can be seen that the life characteristic was lower and the swelling rate was larger compared to the characteristics according to Examples 3 to 5.

[0125] In the case of Comparative Example 7, a discharge capacity of 430 mAh / g could not be obtained, but a low discharge capacity of 410 mAh / g was obtained. It can be seen that both the discharge efficiency and the life characteristic were lower than those of Examples 3 to 5.

[0126] In particular, as Figure 2 shown, in the case of Examples 3 to 5, the discharge capacity did not change significantly with the number of cycles compared to the start, and it can be seen that the discharge capacity was maintained well compared to Comparative Examples 1, 6, and 7.

[0127] As described above, it can be seen that considering the life characteristic, swelling ratio, and discharge efficiency, the optimal composition of the silicon-based composite anode active material that ensures a discharge capacity of 430 mAh / g is as follows: a silicon component and the remaining graphite, based on the total weight of the anode active material, the silicon component including two selected from an amount of Si-M greater than 0 wt% and about 9 wt% or less, an amount of SiO x and an amount of SiC greater than 0 wt% and about 35 wt% or less.

[0128] (3) Discharge capacity of 450 mAh / g

[0129] Table 3 below shows the discharge capacity (mAh / g), discharge efficiency (%), life characteristic (0.5C, 30th cycle), and swelling rate (after the first cycle charge) of Comparative Examples 1 and 8 and Example 6 in which the composition ratio was controlled to have a discharge capacity of about 450 mAh / g. In Table 3, the life characteristic (0.5C) is a value obtained by measuring the ratio (%) of the discharge capacity at the 30th cycle to the initial discharge capacity in each comparative example and example.

[0130] Figure 3It is a graph comparing the life characteristics of Example 6 and Comparative Examples 1 and 8, and it is a graph showing the change in discharge capacity with the number of cycles.

[0131] Table 3

[0132]

[0133] The following will refer to Table 3 and Figure 3 evaluate the Example and each Comparative Example comparatively.

[0134] As shown in Table 3, the discharge capacity of Example 6 is 451.1 mAh / g, indicating a sufficient discharge capacity of about 450 mAh / g. At the same time, a discharge efficiency of 91.0% or higher, a life characteristic of 95.8% or higher (0.5C, 30th cycle), and a swelling rate of 28.0% or lower (after the first cycle charge) can be guaranteed.

[0135] On the other hand, in the case of Comparative Example 1 using only graphite, a discharge capacity of 450 mAh / g could not be obtained, but a low discharge capacity of 360 mAh / g was obtained.

[0136] In the case of Comparative Example 8, it can be seen that the discharge efficiency is lower than that of Example 6.

[0137] In particular, as Figure 3 shown, in the case of Example 6, the discharge capacity does not change significantly with the number of cycles compared to the start, and it can be seen that the discharge capacity remains stable compared to Comparative Examples 1 and 8.

[0138] As described above, it can be seen that considering the life characteristic, swelling ratio, and discharge efficiency, the optimal composition of the silicon-based composite anode active material for ensuring a discharge capacity of 450 mAh / g is as follows: a silicon component and the remaining graphite, based on the total weight of the anode active material, the silicon component including Si-M in an amount greater than 0 wt% and about 11 wt% or less and SiO in an amount greater than 0 wt% and about 35 wt% or less x .

[0139] (4) Discharge capacity of 550 mAh / g

[0140] The following Table 4 shows the discharge capacity (mAh / g), discharge efficiency (%), life characteristic (0.5C, 30th cycle), and swelling rate (after the first cycle charge) of Comparative Examples 1, 9, and 10 and Examples 7 to 9 in which the composition ratio is controlled to have a discharge capacity of about 550 mAh / g. In Table 4, the life characteristic (0.5C) is a value obtained by measuring the ratio (%) of the discharge capacity at the 30th cycle to the initial discharge capacity in each Comparative Example and each Example.

[0141] Figure 4 It is a graph comparing the life characteristics of Examples 7 to 9 and Comparative Examples 1, 9, and 10, and it is a graph showing the change in discharge capacity with the number of cycles.

[0142] Table 4

[0143]

[0144]

[0145] Each example and each comparative example will be evaluated comparatively below with reference to Table 4 and Figure 4 Each example and each comparative example will be evaluated comparatively.

[0146] As shown in Table 4, the discharge capacities of Examples 7 to 9 are 545.3 mAh / g, 550.8 mAh / g, and 547.8 mAh / g, respectively, indicating a sufficient discharge capacity of about 550 mAh / g. At the same time, a discharge efficiency of 80.3% or higher, a life characteristic of 87.3% or higher (0.5C, 30th cycle), and a swelling rate of 41.7% or lower (after the first cycle charge) can be ensured.

[0147] On the other hand, in the case of Comparative Example 1 using only graphite, a discharge capacity of 550 mAh / g could not be obtained, but a low discharge capacity of 360 mAh / g was obtained.

[0148] In the case of Comparative Examples 9 and 10, it can be seen that the life characteristics are lower and the swelling rate is larger compared to Examples 7 to 9.

[0149] In particular, as Figure 4 shown, in the case of Examples 7 to 9, the discharge capacity does not change significantly with the number of cycles compared to the start, and it can be seen that the discharge capacity is maintained well compared to Comparative Examples 1, 9, and 10.

[0150] As described above, it can be seen that considering the life characteristics, swelling ratio, and discharge efficiency, the optimal composition of the silicon-based composite anode active material for ensuring a discharge capacity of 550 mAh / g is as follows: a silicon component and the remaining graphite, based on the total weight of the anode active material, the silicon component including two of Si-M in an amount of more than 0 wt% and 20 wt% or less, SiO x in an amount of more than 0 wt% and about 20 wt% or less, and SiC in an amount of more than 0 wt% and about 60 wt% or less.

[0151] From this, it can be known that compared with the conventional silicon anode, each exemplary embodiment of the present invention can ensure excellent life characteristics and volume expansion suppression ability while ensuring a high energy density.

[0152] Furthermore, it can be seen that, compared with a composition of the same capacity, as the amount of graphite used as a base material increases, durability can be improved and the price can be reduced.

[0153] Exemplary embodiments disclosed with reference to the accompanying drawings and tables have been described above. Those skilled in the art should understand that various changes can be made to the form and details without departing from the spirit and scope of the invention defined by the following claims. The exemplary embodiments are illustrative and should not be construed as restrictive.

Claims

1. An anode active material for a secondary battery, comprising: Graphite; And A silicon component comprising Si-M and SiC, where Si-M is a silicon alloy and M comprises one or more selected from transition metals, alkaline earth metals, Group 13 elements, Group 14 elements, and rare earth elements; Wherein, the anode active material comprises: A silicon component comprising Si-M in an amount greater than 0 wt% and 20 wt% or less and SiC in an amount greater than 0 wt% and 60 wt% or less, and The remaining graphite, All weight percentages are based on the total weight of the anode active material.

2. The anode active material of the secondary battery according to claim 1, wherein The graphite comprises natural graphite, artificial graphite, or a combination thereof.

3. The anode active material of the secondary battery according to claim 1, wherein, M comprises one or more selected from Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Pb, Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, and Te.

4. An anode of a secondary battery, comprising: An anode active material, the anode active material comprising graphite and a silicon component, the silicon component comprising Si-M and SiC, where Si-M is a silicon alloy and M comprises at least one selected from transition metals, alkaline earth metals, Group 13 elements, Group 14 elements, rare earth elements, or a combination thereof; And A conductive material; Wherein, the anode active material comprises: A silicon component comprising Si-M in an amount greater than 0 wt% and 20 wt% or less and SiC in an amount greater than 0 wt% and 60 wt% or less, and The remaining graphite, All weight percentages are based on the total weight of the anode active material.

5. The anode of the secondary battery according to claim 4, wherein, The conductive material comprises one or more selected from graphite, carbon black, CNT, graphene, and graphene oxide.

6. The anode of the secondary battery according to claim 4, wherein, The graphite comprises natural graphite, artificial graphite, or a combination thereof.

7. The anode of the secondary battery according to claim 4, wherein, M comprises one or more selected from Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Pb, Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, and Te.

8. A secondary battery comprising the anode according to claim 4.

9. A vehicle comprising the secondary battery according to claim 8.

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