Title of the invention: Battery system, method of using same, and battery pack comprising same technical field [One] Cross Citation with Related Applications [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0117068 dated September 23, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification. [3] technical field [4] The present invention relates to a battery system, a method of using the same, and a battery pack including the same. background [5] Batteries are widely used in various fields such as electric vehicles (EVs, HEVs, PHEVs) and large-capacity power storage devices (ESSs) as well as mobile devices such as cell phones, laptop computers, smart phones, and smart pads. [6] A battery may be mounted in a device or device, typically as one or more battery modules or battery packs. One or more secondary batteries are provided in such a battery, and in addition to the secondary battery, an electronic device such as a battery management system (BMS) or a case may be further provided. The secondary battery means a battery capable of charging and discharging, unlike a primary battery that cannot be charged. In particular, among various secondary batteries, a lithium secondary battery has been in the spotlight as a driving power source for portable devices because it is lightweight and has a high energy density. Accordingly, research and development efforts for improving the performance of lithium secondary batteries are being actively conducted. [7] In general, a lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte, an organic solvent, and the like. In addition, the positive electrode and the negative electrode may have an active material layer including a positive electrode active material or a negative electrode active material on a current collector. Lithium-containing metal oxides such as LiCoO 2 and LiMn 2 O 4 are generally used for the positive electrode as a positive electrode active material. Accordingly, a carbon-based active material and a silicon-based active material that do not contain lithium are used as the negative electrode active material for the negative electrode. [8] In particular, among the negative active materials, silicon-based active materials are attracting attention in that they have a capacity that is about 10 times higher than that of carbon-based active materials, and due to their high capacity, a high energy density can be realized even with a thin electrode. However, the silicone-based active material is not widely used due to the problem of volume expansion due to charging and discharging, and deterioration of lifespan characteristics by this. [9] Accordingly, there is a need to develop a secondary battery capable of improving the lifespan characteristics while realizing a high capacity and energy density of the silicon-based active material. [10] Korean Patent Laid-Open No. 10-2017-0074030 relates to a negative active material for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery including the same, and discloses a negative active material including a porous silicon-carbon composite. There is a limit to solving it. [11] [Prior art literature] [12] [Patent Literature] [13] Korean Patent Publication No. 10-2017-0074030 DETAILED DESCRIPTION OF THE INVENTION technical challenge [14] It is an object of the present invention to provide a battery system exhibiting improved capacity, energy density, and lifespan characteristics by adjusting a driving voltage range of a secondary battery. [15] Another object of the present invention is to provide a method of using a battery system exhibiting improved capacity, energy density, and lifespan characteristics by adjusting the driving voltage range of a secondary battery. [16] Another object of the present invention is to provide a battery pack including the battery system. means of solving the problem [17] The present invention relates to at least one secondary battery comprising a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte; and a control unit configured to set a driving voltage range during charging and discharging of the secondary battery, wherein the maximum driving voltage of the secondary battery set by the control unit is 4.00V to 4.08V, and the minimum driving of the secondary battery The voltage provides a cell system between 2.98V and 3.07V. [18] In addition, the present invention comprises the steps of manufacturing a battery system including one or more secondary batteries, and a control unit for setting a driving voltage range during charging and discharging of the secondary batteries; and by setting a driving voltage range such that the maximum driving voltage of the secondary battery is 4.00V to 4.08V and the minimum driving voltage 2.98V to 3.07V through the control unit, charging and discharging the secondary battery in at least one cycle It provides a method of using a battery system including a; wherein the secondary battery includes a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte. [19] In addition, the present invention provides a battery pack including the above-described battery system. Effects of the Invention [20] The battery system of the present invention includes a secondary battery including a silicon-based active material, a control unit capable of setting a driving voltage range of the secondary battery to a specific range, and charging and discharging the secondary battery in the driving voltage range set by the control unit can do it Accordingly, the battery system of the present invention can prevent the volume expansion of the silicon-based active material to a desirable level, thereby improving the lifespan performance and at the same time having a high energy density. [21] In addition, according to the method of using the battery system of the present invention, by adjusting the driving voltage range during charging and discharging of the secondary battery including the silicon-based active material to a specific level, the degree of volume expansion of the silicon-based active material is reduced to an appropriate level, thereby improving the lifespan performance. It is possible to drive the battery system so that it can be significantly improved and exhibit a high energy density at the same time. Brief description of the drawing [22] 1 is a graph evaluating the capacity retention rate of secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 7; Modes for carrying out the invention [23] The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention. [24] The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. [25] In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the presence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, elements, or combinations thereof. [26] In the present specification, the average particle diameter (D 50 ) may be defined as a particle diameter corresponding to 50% of the cumulative volume in the particle size distribution curve of the particles. The average particle diameter (D 50 ) may be measured using, for example, a laser diffraction method. In general, the laser diffraction method can measure a particle diameter of several mm from a submicron region, and can obtain results of high reproducibility and high resolution. [27] Hereinafter, the present invention will be specifically described. [28] [29] [30] The present invention relates to a battery system, and specifically to a battery system for a lithium secondary battery. [31] Specifically, the battery system of the present invention includes at least one secondary battery including a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte; and a control unit configured to set a driving voltage range during charging and discharging of the secondary battery, wherein the maximum driving voltage of the secondary battery set by the control unit is 4.00V to 4.08V, and the minimum driving of the secondary battery The voltage is 2.98V to 3.07V. [32] In general, the secondary battery can be operated by charging and discharging in a voltage range of 4.3 ~ 2.5V. However, in the use of a negative electrode and a secondary battery including a silicon-based active material, when charging and discharging are performed within the above range, the degree of volume expansion/contraction of the silicon-based active material is excessive, which may lead to a rapid deterioration in life performance. In order to prevent this, when the voltage range during charging and discharging of the secondary battery is narrowed, the required energy density cannot be satisfied. [33] Accordingly, according to the present invention, by setting the driving voltage range during charging and discharging of the secondary battery to a specific range, volume expansion/contraction of the silicon-based active material is prevented to an appropriate level, thereby significantly improving the life performance of the battery and high energy density can be achieved [34] [35] The secondary battery includes a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte. [36] The negative electrode includes a silicon-based active material, and by controlling a driving voltage range during charging and discharging, which will be described later, prevents volume expansion/contraction of the silicon-based active material while preferably exhibiting high capacity and energy density of the silicon-based active material. [37] The negative electrode may include a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer may include the silicon-based active material. [38] The anode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Specifically, as the negative electrode current collector, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, a surface treatment of copper or stainless steel with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. may be used. can [39] The thickness of the negative electrode current collector may be 3 to 500 μm, preferably 5 to 50 μm, preferably 7 to 20 μm for the thin film implementation of a silicon-based active material-containing negative electrode. [40] The negative electrode current collector may form fine concavities and convexities on the surface to strengthen the bonding strength of the negative electrode active material. For example, the negative electrode current collector may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like. [41] The silicon-based active material may include a compound represented by SiO x (0≤x<2). In the case of SiO 2 , since lithium cannot be stored because it does not react with lithium ions, x is preferably within the above range. [42] Specifically, the silicon-based active material may be Si. Conventionally, Si is advantageous in that its capacity is about 2.5 to 3 times higher than that of silicon oxide (for example, SiO x (0 [107] The present invention provides a method of using a battery system, and more specifically, a method of using the battery system described above. Specifically, the method of using the battery system may be a method of using a battery system for a lithium secondary battery. [108] Specifically, the method of using the battery system of the present invention comprises the steps of: manufacturing a battery system including one or more secondary batteries and a control unit for setting a driving voltage range during charging and discharging of the secondary batteries; and by setting a driving voltage range such that the maximum driving voltage of the secondary battery is 4.00V to 4.08V and the minimum driving voltage 2.98V to 3.07V through the control unit, charging and discharging the secondary battery in at least one cycle performing; including, wherein the secondary battery includes a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte. [109] The method of using the battery system of the present invention sets the maximum driving voltage and the minimum driving voltage to the above-described levels through the control unit, and operates the battery system by charging and discharging the secondary battery from the set maximum driving voltage to the minimum driving voltage. . The secondary battery in which the charging and discharging is performed by adjusting the driving voltage range to the above-described level minimizes volume expansion/contraction of the silicon-based active material, thereby improving lifespan performance and achieving high energy density. [110] The secondary battery and the control unit may be the same as the secondary battery and the control unit described above. [111] [112] [113] In addition, the present invention provides a battery pack including the above-described battery system. [114] The battery pack may further include components known in the art, for example, a battery management system (BMS), a cooling system, and the like, in addition to the secondary battery and the control unit described above. [115] [116] The battery system or battery pack according to the present invention is useful in the field of portable devices such as mobile phones, notebook computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs). The battery system or battery pack may be preferably applied to a power source requiring high output and large capacity, such as an electric vehicle, a hybrid electric vehicle, and a power storage device. [117] [118] Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. [119] [120] [121] Preparation Example 1: Preparation of secondary battery [122] [123] Silicon-based active material Si (average particle diameter (D 50 ): 3.5㎛) as a negative active material , carbon black (product name: Super C65, manufacturer: Timcal) as a conductive material, polyvinyl alcohol and polyacrylic acid as a binder in a weight ratio of 66:34 A negative electrode slurry was prepared by adding the mixture (weight average molecular weight: about 360,000 g/mol) to distilled water as a solvent for forming negative electrode slurry in a weight ratio of 75:10:15 (solid content concentration of 25% by weight). [124] As a negative electrode current collector, the negative electrode slurry was coated on one side of a copper current collector (thickness: 8 μm) in a loading amount of 68.4 mg/25 cm 2 , rolled, and dried in a vacuum oven at 130° C. for 10 hours. A negative electrode active material layer (thickness: 44 μm) was formed to prepare a negative electrode (thickness of the negative electrode: 52 μm). [125] [126] LiNi 0.6 Co 0.2 Mn 0.2 O 2 (average particle size (D 50 ): 10 μm) as a cathode active material, carbon black (product name: Super C65, manufacturer: Timcal) as a conductive material, and polyvinylidene fluoride (PVdF) as a binder A positive electrode slurry was prepared by adding N-methyl-2-pyrrolidone (NMP) as a solvent for forming the positive electrode slurry in a weight ratio of 97:1.5:1.5 (solids concentration of 72% by weight). [127] As a positive electrode current collector, the positive electrode slurry was coated on one side of an aluminum current collector (thickness: 12 μm) in a loading amount of 459.4 mg/25 cm 2 , rolled, and dried in a vacuum oven at 130° C. for 10 hours. A positive electrode active material layer (thickness: 110 μm) was formed to prepare a positive electrode (anode thickness: 122 μm). [128] [129] A polyethylene/polypropylene/polyethylene separator was interposed between the negative electrode and the positive electrode prepared above, and electrolyte was injected to prepare a secondary battery of Preparation Example 1. The electrolyte is an organic solvent in which fluoroethylene carbonate (FEC) and diethyl carbonate (DMC) are mixed in a volume ratio of 30:70, vinylene carbonate is added in an amount of 3% by weight based on the total weight of the electrolyte, and LiPF 6 as a lithium salt was added at a concentration of 1M. [130] [131] A negative electrode sample was prepared by cutting the prepared negative electrode to a predetermined size. A lithium metal electrode having the same size as that of the negative electrode sample was prepared, and it was opposed to the negative electrode sample. After interposing a polyethylene separator between the negative electrode sample and the lithium metal electrode, an electrolyte was injected to prepare a coin-type half-cell. As the electrolyte, an organic solvent in which ethylene carbonate and ethylmethyl carbonate were mixed in a volume ratio of 50:50 was used as a lithium salt in which LiPF 6 was added at a concentration of 1M. The discharge capacity obtained by charging/discharging the coin-shaped half-cell at 0.1 C was divided by the weight of the negative active material contained in the negative electrode sample to obtain the discharge capacity of the negative electrode sample per unit weight of the negative electrode active material. [132] In addition, the positive electrode prepared above was cut to a predetermined size to prepare a positive electrode sample. A lithium metal electrode having the same size as the positive electrode sample was prepared, and it was opposed to the positive electrode sample. After interposing a polyethylene separator between the positive electrode sample and the lithium metal electrode, an electrolyte was injected to prepare a coin-type half-cell. As the electrolyte, an organic solvent in which ethylene carbonate and ethylmethyl carbonate were mixed in a volume ratio of 50:50 was used as a lithium salt in which LiPF 6 was added at a concentration of 1M. The discharge capacity obtained by charging/discharging the coin-type half-cell at 0.1 C was divided by the weight of the positive active material contained in the positive electrode sample to obtain the discharge capacity of the positive electrode sample per unit weight of the positive electrode active material. [133] The discharge capacity of the negative electrode sample per unit weight of the negative electrode active material measured above is multiplied by the weight of the negative electrode active material of the secondary battery prepared in Preparation Example 1, and divided by the area of ​​the negative electrode to obtain the discharge capacity per unit area of ​​the negative electrode of Preparation Example 1 did In addition, the discharge capacity of the positive electrode sample per unit weight of the positive electrode active material was multiplied by the weight of the positive electrode active material of the secondary battery prepared in Preparation Example 1 and divided by the area of ​​the positive electrode to obtain the discharge capacity per unit area of ​​the positive electrode of Preparation Example 1. [134] An N/P ratio of 2.0 was obtained by dividing the discharge capacity per unit area of ​​the negative electrode by the discharge capacity per unit area of ​​the positive electrode. [135] [136] Preparation Example 2: Preparation of secondary battery [137] [138] The negative electrode slurry in Preparation Example 1 was coated with a loading amount of 88.8 mg/25 cm 2 on one surface of a copper current collector (thickness: 8 μm) as a negative electrode current collector , rolled, and 10 in a vacuum oven at 130° C. By drying for a period of time to form a negative electrode active material layer (thickness: 57㎛), a negative electrode was prepared (thickness of the negative electrode: 65㎛). [139] [140] The positive electrode prepared in Preparation Example 1 was used. [141] [142] A secondary battery of Preparation Example 2 was prepared in the same manner as in Preparation Example 1 except that the negative electrode and positive electrode prepared above were used. [143] [144] In the same manner as in Preparation Example 1, the N/P ratio (=2.6) of the secondary battery of Preparation Example 2 was measured. [145] [146] [147] Examples 1-3 and Comparative Examples 1-7 [148] [149] The secondary batteries of Preparation Examples 1 and 2 prepared above were connected to an electrochemical charger/discharger. [150] As shown in Table 1 below, the battery systems of Examples 1 to 3 and Comparative Examples 1 to 7 were prepared by adjusting the type of secondary battery and the maximum driving voltage and the minimum driving voltage set in the control unit as follows. [151] [152] [Table 1] [153] [154] Experimental example [155] Experimental Example 1: Thickness expansion rate when fully charged [156] Examples 1 to 3 and Comparative Examples 1 to 7 were charged in CC / CV mode to the maximum voltage of Table 1 at 0.5C (maximum voltage in Table 1, current cut-off at 0.05C), The negative electrode thickness expansion rate when fully charged according to Equation 2 was measured. [157] [Equation 2] [158] Anode thickness expansion rate when fully charged (%) = {(d a2 -d a1 )/d a1 } × 100 [159] In Equation 2, d a2 is the thickness of the negative active material layer when fully charged, and d a1 is the thickness of the negative active material layer before charging. The results are shown in Table 2 below. [160] [161] Experimental Example 2: Difference in thickness change between full charge/full discharge [162] The battery systems prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were charged and discharged under the following conditions to calculate the difference (%) in thickness change between full charge/full discharge according to Equation 3 below. [163] [164] Charging: Charging in CC/CV mode up to the maximum voltage in Table 1 at 0.5C (maximum voltage in Table 1, current cut-off at 0.05C) [165] Discharge: Discharge in CC mode up to the minimum voltage in Table 1 at 0.5C (cut-off at the minimum voltage in Table 1) [166] [Equation 3] [167] Difference in thickness change between full charge/full discharge (%) = {(d b2 -d b1 )/d b1 } × 100 [168] In Equation 3, d b2 is the thickness of the negative active material layer when fully charged, and d b1 is the thickness of the negative active material layer when fully discharged. The results are shown in Table 2 below. [169] [170] Experimental Example 3: Capacity retention rate [171] The capacity retention rates of the battery systems prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were evaluated. [172] The secondary battery was charged and discharged up to the 200th cycle under the following charging and discharging conditions. The capacity retention rate was evaluated by Equation 4 below. The results are shown in Figs. 1 and 2 below. [173] [174] Charging: Charging in CC/CV mode up to the maximum voltage in Table 1 at 0.5C (maximum voltage in Table 1, current cut-off at 0.05C) [175] Discharge: Discharge in CC mode up to the minimum voltage in Table 1 at 0.5C (cut-off at the minimum voltage in Table 1) [176] [Equation 4] [177] Capacity retention rate (%) = {(discharge capacity in 200th cycle)/(discharge capacity in 1st cycle)} × 100 [178] [179] Experimental Example 4: Energy Density [180] The battery systems prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were charged and discharged once under the following charging and discharging conditions. [181] [182] Charging: Charging in CC/CV mode up to the maximum voltage in Table 1 at 0.5C (maximum voltage in Table 1, current cut-off at 0.05C) [183] Discharge: Discharge in CC mode up to the minimum voltage in Table 1 at 0.5C (cut-off at the minimum voltage in Table 1) [184] [185] Then, the energy density of the negative electrode in the battery systems of Examples 1 to 3 and Comparative Examples 1 to 7 was measured and calculated by Equation 5 below. [186] [Equation 5] [187] Energy density (Wh/L) = {discharge capacity (Ah) in first cycle × average voltage (V)}/(volume of cathode at completion of charge in first cycle (L)) [188] In Equation 5, the average voltage is obtained by multiplying the voltage, the current, and the discharge execution time at the time when the minimum voltage is reached and the discharge is completed to obtain Wh (Watt-hour), which is obtained by dividing it by the discharge capacity in the first cycle. [189] [190] [Table 2] [191] [192] Referring to Table 2, it can be seen that in Examples 1 to 3 using the battery system according to the present invention, the lifespan characteristics and the energy density are simultaneously improved. [193] On the other hand, in the case of Comparative Examples 1 to 7 in which charging and discharging were not performed at the maximum and minimum driving voltages of the present invention, it is difficult to exert sufficient capacity of the silicon-based active material, so that the energy density is too low, or it is difficult to control the volume expansion of the silicon-based active material. It can be seen that the characteristics are too low. Claims [Claim 1] One or more secondary batteries including a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte; and a control unit configured to set a driving voltage range during charging and discharging of the secondary battery, wherein the maximum driving voltage of the secondary battery set by the control unit is 4.00V to 4.08V, and the minimum driving of the secondary battery A battery system in which the voltage is 2.98V to 3.07V. [Claim 2] The battery system according to claim 1, wherein the silicon-based active material is Si. [Claim 3] The battery system of claim 1 , wherein the negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer includes the silicon-based active material, a binder, and a conductive material. [Claim 4] The method according to claim 3, wherein the binder is styrene butadiene rubber, acrylonitrile butadiene rubber, acrylic rubber, butyl rubber, fluoro rubber, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol, poly A battery system comprising at least one selected from the group consisting of acrylic acid, polyethylene glycol, polyacrylonitrile, and polyacrylamide. [Claim 5] The method according to claim 3, wherein the silicon-based active material is included in the anode active material layer in an amount of 60 wt% to 90 wt%, the binder is included in an amount of 5 wt% to 30 wt% in the anode active material layer, and the conductive material is the anode active material A cell system included in the layer in an amount of 5% to 20% by weight. [Claim 6] The battery system according to claim 3, wherein the negative active material layer has a thickness of 35 μm to 50 μm. [Claim 7] The battery system according to claim 1, wherein the N/P ratio calculated by Equation 1 below of the secondary battery is 1.5 to 3.5: [Equation 1] N/P ratio = Discharge capacity per unit area of ​​negative electrode / Discharge per unit area of ​​positive electrode Volume. [Claim 8] The battery system according to claim 1, wherein the positive active material includes a lithium transition metal composite oxide, and the lithium transition metal composite oxide includes lithium and at least one transition metal consisting of nickel, cobalt, manganese, and aluminum. [Claim 9] manufacturing a battery system including at least one secondary battery and a control unit for setting a driving voltage range during charging and discharging of the secondary battery; and by setting a driving voltage range such that the maximum driving voltage of the secondary battery is 4.00V to 4.08V and the minimum driving voltage 2.98V to 3.07V through the control unit, charging and discharging the secondary battery in at least one cycle A method of using a battery system, including:, wherein the secondary battery includes a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte. [Claim 10] A battery pack comprising the battery system according to claim 1 .