Title of the invention: Anode active material for lithium secondary battery and secondary battery containing the same
Technical field
[One]
The present invention relates to a negative active material for a lithium secondary battery and a secondary battery including the same, and more specifically, to a negative active material including low expansion artificial graphite exhibiting low expansion characteristics during charge and discharge, and a lithium secondary battery including the same.
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0160091 filed on Dec. 12, 2018, and all contents disclosed in the documents of the Korean patent application are included as part of this specification.
Background
[3]
As the price of energy sources rises due to the depletion of fossil fuels and interest in environmental pollution increases, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life. In particular, technology development for mobile devices As the demand and demand increase, the demand for secondary batteries as an energy source is rapidly increasing.
[4]
Typically, in terms of the shape of the battery, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with a thin thickness. In terms of materials, lithium-ion batteries with high energy density, discharge voltage, and output stability, There is high demand for lithium secondary batteries such as lithium ion polymer batteries.
[5]
In general, secondary batteries form a positive electrode and a negative electrode by coating an electrode mixture containing an electrode active material on the surface of a current collector, and form an electrode assembly with a separator interposed therebetween. It is mounted inside the pouch-shaped case of the electrode assembly, and is manufactured by mainly injecting or impregnating a liquid electrolyte into the electrode assembly or using a solid electrolyte.
[6]
[7]
Carbon-based materials such as graphite are mainly used for the negative electrode of a lithium secondary battery, but the theoretical capacity density of carbon is 372mAh/g (833mAh/cm 3 ). Therefore, in order to improve the energy density of the negative electrode, silicon (Si) and tin (Sn) alloyed with lithium, oxides and alloys thereof, and the like are being studied as negative electrode materials. Among them, silicon-based materials have attracted attention due to their low price and high capacity (4200mAh/g).
[8]
However, although the silicon-based material exhibits a much higher theoretical capacity than graphite, when silicon meets lithium ions, the volume expands more than four times. As a result, there is a problem in that the conductive network of the battery is lost and the charge/discharge capacity rapidly decreases. In addition, as the initial efficiency of the cycle decreases, the advantage of a silicon-based material capable of realizing a high energy density may disappear. In particular, in the case of a cylindrical battery, when the volume of the silicon-based material expands and the diameter of the wound cell increases, storage becomes difficult, and thus it is difficult to increase the energy density.
[9]
[10]
Accordingly, studies have been continuously made to overcome the low energy density limit of the carbon-based material negative active material and to reduce side effects due to the expansion characteristics of the silicon-based material.
[11]
Japanese Patent Laid-Open No. 2018-008405 describes a method of manufacturing a composite of carbon particles having fine irregularities and using it as a negative electrode material together with silicon oxide so that the cycle characteristics do not deteriorate even when the expansion and contraction of silicon oxide during charging and discharging. have.
[12]
On the other hand, Korean Patent Publication No. 2017-0136878 describes a method of improving lifespan characteristics and high-temperature storage characteristics by using secondary particle artificial graphite including primary particles having a specific average particle diameter as a negative electrode active material.
[13]
In addition, Korean Patent No. 1704103 discloses a method of improving life characteristics by suppressing volume expansion of the negative electrode active material and solving a short circuit problem by including porous silicon-based particles and fine and granulated carbon particles having different average particle diameters together.
[14]
In addition, in the negative electrode active material including carbon-based and silicon-based materials to realize high energy density, metal-based materials are added to reduce side effects due to volume expansion of the silicon-based material, or a new composite is prepared or particle size. Various methods are being studied, such as changing.
Detailed description of the invention
Technical challenge
[15]
The present invention relates to a negative active material for a lithium secondary battery and a secondary battery including the same, and the negative active material according to the present invention includes a carbon-based material and a silicon-based material, while achieving high energy density, and has low expansion characteristics in the carbon-based material. By including the artificial graphite having a certain amount, it is characterized in that the loss of the conductive network is prevented by suppressing the volume expansion of the electrode.
A means to solve the task
[16]
The present invention relates to a negative active material for a lithium secondary battery and a secondary battery including the same, wherein the negative active material according to the present invention is a negative active material for a lithium secondary battery including a carbon-based material and a silicon-based material, and the carbon-based material is a low-expansion artificial It characterized in that it contains graphite. At this time, the low-expansion artificial graphite exhibits low expansion characteristics during battery charging and discharging, and the volume expands to less than 25%, more preferably less than 23% from the initial state even if the charging/discharging cycle is repeated.
[17]
If the carbon-based material includes artificial graphite whose volume expands by 25% or more compared to the initial state, or is a natural graphite or other carbon-based material having high expansion characteristics, the cycle characteristics may rapidly deteriorate.
[18]
[19]
In addition, the low-expansion artificial graphite may preferably be included in 65 to 95% by weight, more preferably 75 to 85% by weight based on the total weight of the negative active material. If less than 65% of the low-expansion artificial graphite is contained relative to the total weight of the carbon-based material, the energy density may be lowered due to a decrease in initial efficiency during the repetition of charge/discharge cycles when manufacturing a secondary battery. On the other hand, even if the content of the artificial graphite exceeds 95% by weight, no apparent increase in the effect does not appear, and it is not preferable because the economical efficiency is inferior when considering the manufacturing cost of the low-expansion artificial graphite.
[20]
[21]
Meanwhile, the carbon-based material may further include a known carbon-based material used for a negative electrode for a lithium secondary battery in addition to the low-expansion artificial graphite, and natural graphite, which is generally widely used, may be selected. Therefore, in the case of including the low-expansion artificial graphite in the above weight% range, it is economically preferable to use natural graphite as the remaining carbon-based material.
[22]
[23]
The negative electrode active material according to the present invention includes a silicon-based material, and the content of the silicon-based material based on the total weight of the negative electrode active material may be preferably 1 to 10% by weight, more preferably 3 to 7% by weight. Silicon-based materials are included in order to maximize energy density characteristics, and when added in less than 1% by weight, the energy density improvement effect does not appear, and when less than 10% by weight, energy density is rather low due to the volume expansion characteristics of the silicon-based material Losing has an adverse effect.
[24]
[25]
In this case, the silicon-based material may include one or two or more silicon oxide-based materials, and specifically, silicon dioxide (SiO 2 ) may be used.
[26]
[27]
A negative electrode for a lithium secondary battery can be manufactured by applying the above-described negative active material to one or both sides of a negative electrode current collector, and when such a negative electrode for a lithium secondary battery is applied, a lithium secondary battery whose energy density is maximized according to the characteristics of the silicon-based negative material Can be manufactured. In particular, the negative active material for a lithium secondary battery of the present invention and the negative electrode using the same are most effective when applied to a cylindrical secondary battery mainly using a silicon-based negative electrode material.
Effects of the Invention
[28]
The present invention relates to an anode active material comprising a carbon-based material and a silicon-based material, containing a certain amount or more of low-expansion artificial graphite, and energy density and cycle due to volume expansion that may appear in the anode active material comprising a silicon-based material. This is an improvement over the disadvantages of deteriorating properties. In particular, the present invention does not need to reduce the volume expansion rate of the silicon-based material itself, or change or process the shape, particle diameter, structure, etc. of the carbon-based material, as in the prior art, so that the manufacturing process is simple and economical is excellent.
Brief description of the drawing
[29]
FIG. 1 shows the expansion characteristics of natural graphite, low-expansion artificial graphite (artificial graphite A), and conventional artificial graphite (artificial graphite B) according to charge and discharge cycles.
[30]
FIG. 2 shows a comparison of cycle characteristics according to types of carbon-based materials used for negative electrode active materials in secondary batteries manufactured according to Examples and Comparative Examples of the present invention.
[31]
FIG. 3 is a diagram showing a comparison of cycle characteristics according to the content of a silicon-based material used in a negative electrode active material in a secondary battery manufactured according to Examples and Comparative Examples of the present invention.
[32]
4 is a diagram showing a comparison of cycle characteristics according to the content of low-expansion artificial graphite used in a negative electrode active material in a secondary battery manufactured according to Examples and Comparative Examples of the present invention.
[33]
5 is a diagram showing a comparison of cycle characteristics according to a low-expansion artificial graphite content in a secondary battery manufactured according to Examples and Comparative Examples of the present invention.
Mode for carrying out the invention
[34]
Terms used in the present specification and claims are not limited to their usual or dictionary meanings and should not be interpreted, and that the inventor can appropriately define the concept of terms in order to describe his own invention in the best way. Based on the principle, it should be interpreted as a meaning and concept consistent with the technical idea of ​​the invention. Therefore, the configuration shown in the embodiments described in the present specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of the present application And it should be understood that there may be variations.
[35]
Throughout the specification of the present application, the term "low-expansion artificial graphite" refers to artificial graphite having low expansion characteristics during a charge/discharge cycle. Specifically, when an active material layer in which artificial graphite is applied as a negative electrode material is formed on a negative electrode current collector to prepare a negative electrode, and a secondary battery having such a negative electrode is manufactured, the active material layer is repeated even when the charge/discharge cycle of the secondary battery is repeated. When the expansion characteristic of is low, such artificial graphite is referred to as "low expansion artificial graphite" in the present specification.
[36]
In the entire specification of the present application, the "expanding characteristic of low-expansion artificial graphite" is represented by the change in the thickness of the active material layer of the low-expansion artificial graphite according to the charge/discharge cycle. Specifically, after manufacturing a negative electrode using low-expansion artificial graphite as an active material and a secondary battery including the negative electrode, the charge/discharge cycle is repeated until there is no change in the thickness of the negative electrode active material layer. Thereafter, the thickness of the negative electrode active material layer before charging and discharging cycles is compared with the thickness of the active material layer after charging and discharging cycles.
[37]
In the entire specification of the present application, when a certain part "includes" a certain constituent element, it means that other constituent elements may be further included rather than excluding other constituent elements unless otherwise stated.
[38]
The terms "about", "substantially" and the like used throughout this specification are used as a meaning at or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are accurate to aid the understanding of the present application. Or absolute figures are used to prevent unreasonable use of the stated disclosure by unconscionable infringers.
[39]
In the entire specification of the present application, the term "combination(s) thereof" included in the expression of the Makushi form means one or more mixtures or combinations selected from the group consisting of the constituent elements described in the expression of the Makushi form, It means to include at least one selected from the group consisting of the above constituent elements.
[40]
The present invention relates to a cathode for an electrochemical device and an electrochemical device including the same. In the present invention, the electrochemical device includes all devices that undergo an electrochemical reaction, and specific examples include all types of primary and secondary batteries, fuel cells, solar cells, or capacitors. Particularly, among the secondary batteries, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery is preferred.
[41]
In the entire specification of the present application, the description of "A and/or B" means "A or B or both".
[42]
[43]
Hereinafter, the present invention will be described in more detail.
[44]
[45]
The present invention relates to a negative active material for a lithium secondary battery and a secondary battery including the same, wherein the negative active material according to the present invention is a negative active material for a lithium secondary battery including a carbon-based material and a silicon-based material, and the carbon-based material is a low-expansion artificial It characterized in that it contains graphite. As described above, in the negative active material, when only a carbon-based material is used as the negative active material, the energy density is low, so there is a limit to the design of the battery capacity. In order to overcome this limitation, when lithium and silicon-based materials are included in the negative electrode active material, energy density is increased, and a high-capacity battery can be implemented. However, since the silicon-based material has high expansion characteristics, it may cause disconnection of the conductive network as the charge/discharge cycle is repeated, so when it is included in a high content, there is a side effect of lowering the energy density or lowering the life characteristics. .
[46]
As described above, various studies have been conducted to improve the cycle characteristics of the negative electrode active material including carbon-based materials and silicon-based materials.As described above, in the prior art, a method of modifying carbon-based particles or silicon-based particles or adding additional materials Are presented.
[47]
Specifically, in the case of carbon-based materials, a method of preventing disconnection due to volume expansion of the silicon-based material and prolonging the life characteristics is preceded by a method such as changing the particle surface shape, adjusting the particle size, manufacturing secondary particles, and manufacturing a composite. Disclosed in the inventions.
[48]
For example, in Japanese Patent Application Laid-Open No. 2018-008405, a carbon composite is manufactured in order to modify the shape of carbon particles to have fine irregularities. It is described that when the carbon composite and silicon oxide are used together as a negative electrode material, the effect of not deteriorating the cycle characteristics despite the volume expansion of the silicon-based material silicon oxide.
[49]
In addition, Korean Patent Publication No. 2017-0136878 discloses that a similar effect was obtained by preparing a negative electrode active material including primary particles having a particle diameter adjusted as a carbon-based material and secondary particles including the same.
[50]
On the other hand, with respect to a method of directly suppressing the volume expansion of silicon-based particles, Korean Patent No. 1704103 provides porous silicon-based particles, and these porous silicon particles and fine and granulated carbon particles having different average particle diameters are mixed together. It provides a negative active material containing
[51]
[52]
The present invention has solved the problems of the prior art by approaching and solving the problems of the prior art in a manner different from the above-described prior literature, and provides a negative active material comprising a certain amount of low-expansion artificial graphite relative to the total weight of the carbon-based material.
[53]
[54]
In the case of carbon-based materials, unlike silicon-based materials, the expandability of carbon-based materials is not high, so there has not been an in-depth study on the volume expansion of carbon-based materials. However, according to an experiment conducted by the present applicant, when a negative electrode active material is prepared by including a low-expansion artificial graphite having a relatively low expansion characteristic in a certain amount, even if a silicon-based material having a large volume expansion characteristic is included, the initial cycle efficiency decreases. The unexpected effect of this improvement appeared. Accordingly, in the case of a negative electrode to which the negative electrode active material of the present invention is applied and a secondary battery having such a negative electrode, it is possible to realize high capacity without modification or additional processing of the carbon-based material while using the existing known silicon-based material as it is without processing Do.
[55]
[56]
Specifically, the negative active material according to the present invention is a negative active material for a lithium secondary battery including a carbon-based material and a silicon-based material, and the carbon-based material includes low-expansion artificial graphite. In this case, the low-expansion artificial graphite is used that exhibits low expansion characteristics during charging and discharging of the battery. According to an embodiment of the present invention, the low-expansion artificial graphite may be used in which the volume expands to less than 25%, more preferably less than 23% from the initial state even when the charge/discharge cycle is repeated. As shown in Examples and Comparative Examples to be described later, when graphite or natural graphite that expands by 25% or more is used, the energy density of the battery, which is a characteristic of a negative electrode active material including a silicon-based material, decreases.
[57]
In addition, the low-expansion artificial graphite may be included preferably 65 to 95% by weight, more preferably 75 to 85% by weight based on the total weight of the carbon-based material. If less than 65% of the low-expansion artificial graphite is contained relative to the total weight of the carbon-based material, the energy density may be lowered due to a decrease in initial efficiency during the repetition of charge/discharge cycles when manufacturing a secondary battery. On the other hand, even if the content of the artificial graphite exceeds 95% by weight, no apparent increase in the effect does not appear, and it is not preferable because the economical efficiency is inferior when considering the manufacturing cost of the low-expansion artificial graphite.
[58]
[59]
Meanwhile, the carbon-based material may further include a known carbon-based material used for a negative electrode for a lithium secondary battery in addition to the low-expansion artificial graphite, and natural graphite, which is generally widely used, may be selected. Therefore, in the case of including the low-expansion artificial graphite in the above weight% range, it is economically preferable to use natural graphite that is inexpensive and easy to obtain as the remaining carbon-based material.
[60]
[61]
The negative electrode active material according to the present invention includes a silicon-based material, and the content of the silicon-based material based on the total weight of the negative electrode active material may be preferably 1 to 10% by weight, more preferably 3 to 7% by weight. Silicon-based materials are included in order to maximize energy density characteristics, and when added in less than 1% by weight, the energy density improvement effect does not appear, and when less than 10% by weight, energy density is rather low due to the volume expansion characteristics of the silicon-based material Losing has an adverse effect. Therefore, in order to obtain excellent energy density characteristics, it is preferable to adjust the content within the above range in which the advantages of the silicon-based material can be utilized.
[62]
[63]
In this case, the silicon-based material may include one or more silicon oxide-based materials, and silicon and/or silicon oxide may be used. According to an embodiment of the present invention, silicon dioxide (SiO 2 ) may be preferably used, and when it is included according to the composition ratio, a desirable effect was exhibited.
[64]
[65]
A negative electrode for a lithium secondary battery can be manufactured by applying the above-described negative active material to one or both sides of a negative electrode current collector, and when such a negative electrode for a lithium secondary battery is applied, a lithium secondary battery whose energy density is maximized according to the characteristics of the silicon-based negative material Can be manufactured. In particular, the negative active material for a lithium secondary battery of the present invention and the negative electrode using the same are most effective when applied to a cylindrical secondary battery mainly using a silicon-based negative electrode material. However, the negative electrode active material according to the present invention and the application of the negative electrode using the same can be applied to various types of secondary batteries, and are not limited to the above-described cylindrical secondary battery types.
[66]
[67]
Hereinafter, examples will be described in detail to aid understanding of the present invention. However, the embodiments according to the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the following examples. Embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.
[68]
[69]

[70]
[71]
Preparation of carbon-based material
[72]
[73]
Natural graphite, artificial graphite A, which is a low expansion artificial graphite with low expansion characteristics, and artificial graphite B, which are commonly used were prepared, respectively.
[74]
[75]
Manufacture of coin cell
[76]
[77]
In order to compare the expansion characteristics, each of the natural graphite, artificial graphite A, and artificial graphite B was independently prepared as a negative electrode active material.
[78]
A specific method of manufacturing a coin half battery is as follows.
[79]
94 wt% of a negative electrode active material, 2 wt% of multi-walled carbon nanotubes having an average diameter of 20 nm and an average length of 2 µm as a conductive material, and 4 wt% of polyvinylidene fluoride as a binder were mixed, and N-methyl2-pyrrolidone was mixed. After the slurry was formed by using, it was applied to a copper foil having a thickness of 20 µm to a thickness of about 100 µm, dried and pressed in a vacuum at 120°C, and then punched into a circular shape having a diameter of 13 mm to prepare a negative electrode. A coin cell was prepared using a punched negative electrode and an electrolytic solution in which a metal lithium having a thickness of 0.3 mm was used as a counter electrode, ethylene carbonate and diethyl carbonate were mixed in a ratio of 3:7 and 1 mol of LiPF 6 was dissolved .
[80]
[81]
Measurement of expansion characteristics according to charge and discharge cycles
[82]
[83]
For each of the coin cells, a charge/discharge cycle of charging to 4.25V and then discharging to 2.5V was repeated for each of the coin cells, and the thickness of the negative active material was measured for each cycle to derive the expansion ratio for each negative active material. The results are shown in FIG. 1.
[84]
As shown in Figure 1, natural graphite showed a constant volume expansion rate of 28% after 10 cycles. Artificial graphite A had a constant volume expansion rate of 22% after 6 cycles, and artificial graphite B had a constant volume expansion rate of 25% after 7 cycles.
[85]
[86]

[87]
[88]
Example 1
[89]
[90]
Artificial graphite A, natural graphite, and silicon oxide were mixed so that the weight ratio was 75:20:5, and used as a negative electrode active material. Other than that, a coin cell was manufactured in the same manner as in the measurement of the expansion characteristics of the carbon-based material, and a charge/discharge cycle of charging to 4.25V and then discharging to 2.5V was repeated 200 times.
[91]
[92]
Comparative Example 1
[93]
[94]
The experiment was carried out in the same manner as in Example 1, except that natural graphite and silicon dioxide were mixed so as to have a weight ratio of 95: 5 and used as a negative electrode active material.
[95]
[96]
Comparative Example 2
[97]
[98]
The experiment was carried out in the same manner as in Example 1, except that artificial graphite B, natural graphite, and silicon oxide were mixed so as to be 75:20:5 and used as a negative electrode active material.
[99]
[100]
Results and Discussion
[101]
[102]
The cycle characteristics according to each of the Examples and Comparative Examples are shown in FIG. 2. In the case of Example 1 containing 75% by weight of artificial graphite A having an expansion property of 22% based on the total weight of the negative active material, the cycle characteristics were excellent. On the other hand, in the case of Comparative Examples 1 and 2 in which natural graphite and artificial graphite B having 25% expansion characteristics were applied, the tendency to decrease in capacity was remarkable after only 50 cycles, and a large difference occurred in battery capacity after 200 cycles.
[103]
[104]

[105]
[106]
Comparative Example 3
[107]
[108]
The experiment was carried out in the same manner as in Example 1, except that artificial graphite B, natural graphite, and silicon oxide were mixed to be 75:10:15 and used as a negative electrode active material.
[109]
[110]
Results and Discussion
[111]
[112]
The cycle characteristics of Comparative Example 3 and Example 1 are also shown in FIG. 3. Comparing FIGS. 2 and 3 together, in the case of Comparative Example 3 in which the content of silicon dioxide exceeds 10% by weight with respect to the total weight of the negative active material, it appears that the cycle characteristics are further lowered than in Comparative Example 2. From this, it can be seen that when the content of silicon dioxide exceeds 10% by weight, the cycle characteristics are rather deteriorated.
[113]
[114]

[115]
[116]
Comparative Example 4
[117]
[118]
The experiment was carried out in the same manner as in Example 1, except that artificial graphite A, natural graphite, and silicon oxide were mixed so as to be 30:65:5 and used as a negative electrode active material.
[119]
[120]
Comparative Example 5
[121]
[122]
The experiment was carried out in the same manner as in Example 1, except that artificial graphite A, natural graphite, and silicon oxide were mixed so as to be 50:45:5 and used as a negative electrode active material.
[123]
[124]
Example 2
[125]
[126]
The experiment was carried out in the same manner as in Example 1, except that artificial graphite A, natural graphite, and silicon oxide were mixed to be 85:10:5 and used as a negative electrode active material.
[127]
[128]
Results and Discussion
[129]
[130]
Experimental results according to the above Examples and Comparative Examples are shown in FIGS. 4 and 5 together with Example 1. First, in the case of Comparative Examples 4 and 5 in which the artificial graphite content is 30% by weight and 50% by weight based on the total weight of the negative active material, the capacity characteristics tend to be lowered at the beginning. In addition, 85% by weight of Example 2 was found to have finely superior capacity characteristics after 200 cycles compared to Example 1. Therefore, when at least 65% by weight of low-expansion artificial graphite is included, the cycle characteristics are improved, and the higher the content, the more improved the effect, but the improvement effect was not large from 75% or more. In view of this trend, considering economics, the content range of the low-expansion artificial graphite is preferably 95% by weight or less, and more specifically 75% to 85% by weight is most preferable.
Claims
[Claim 1]
A negative active material for a lithium secondary battery comprising a carbon-based material and a silicon-based material, wherein the carbon-based material includes low-expansion artificial graphite, and the low-expansion artificial graphite expands to less than 25% in volume during battery charging and discharging. Anode active material for lithium secondary batteries.
[Claim 2]
The negative active material of claim 1, wherein the low-expansion artificial graphite is contained in an amount of 65 to 95% by weight based on the total weight of the negative active material.
[Claim 3]
The negative active material of claim 1, wherein the low-expansion artificial graphite is contained in an amount of 75 to 85% by weight based on the total weight of the negative active material.
[Claim 4]
The negative active material of claim 1, wherein the carbon-based material is made of natural graphite and artificial graphite.
[Claim 5]
The negative active material of claim 1, wherein the silicon-based material is contained in an amount of 1 to 10% by weight based on the total weight of the negative active material.
[Claim 6]
The negative active material of claim 1, wherein the silicon-based material is contained in an amount of 3 to 7% by weight based on the total weight of the negative active material.
[Claim 7]
The negative active material of claim 1, wherein the silicon-based material is silicon dioxide (SiO 2 ).
[Claim 8]
The negative active material of claim 1, wherein the low-expansion artificial graphite expands to less than 23% in volume during charging and discharging of the battery.
[Claim 9]
Current collector; And a negative active material layer formed on at least one surface of the current collector and including a negative active material, wherein the negative active material is the negative active material according to claim 1.
[Claim 10]
A lithium secondary battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the negative electrode is the negative electrode according to claim 8.
[Claim 11]
The lithium secondary battery according to claim 10, wherein the lithium secondary battery is a cylindrical secondary battery.