KR101423595B1 - Secondary Battery Pack with Battery Cell Having Improved Low Temperature Property - Google Patents

Abstract

The present invention is characterized in that a plurality of battery cells are electrically connected to each other and a battery cell A having a capacity of 10% or less based on the total number of battery cells is superior in low temperature performance to the remaining battery cells B, A) is characterized in that the electrode and / or the electrolyte include a composition exhibiting low-temperature high-output characteristics.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery pack,

The present invention relates to a secondary battery pack, more specifically, a plurality of battery cells are electrically connected, and a battery cell (A) of 10% or less based on the total number of battery cells is connected to a remaining battery cell (B) Temperature performance, and the battery cell (A) includes a composition in which electrodes and / or electrolytes exhibit low-temperature high-output characteristics.

One of the biggest problems with vehicles using fossil fuels such as gasoline and diesel is that it causes air pollution. As a solution to this problem, a technique of using a power source of a vehicle as a secondary battery capable of charging and discharging has attracted attention. Accordingly, an electric vehicle (EV) that can be operated only by a battery, and a hybrid electric vehicle (HEV) that uses a battery and an existing engine have been developed, and some of them have been commercialized. BACKGROUND ART [0002] Nickel metal hydride (Ni-MH) batteries are mainly used as secondary batteries as power sources for EV, HEV and the like, but recently lithium-ion batteries have also been used.

EV, HEV, etc., a high output large capacity is required. Therefore, in general, a battery pack having a structure in which a plurality of small secondary battery cells (unit cells) are connected in series and / or in parallel is used.

A general battery pack is composed of a battery module having the same characteristics such as output and capacity.

Specifically, the conventional battery pack includes a battery module including a plurality of battery cells having the same characteristics such as output and capacity, a control unit for controlling the operation thereof, and an external input / output terminal for connecting the battery module to the device.

Generally, the device must be able to satisfy all of the various driving conditions. That is, it should be able to operate properly at a temperature of minus 20 ° C or lower, and be able to operate without fail even at a temperature of 40 ° C or higher. In addition, since the initial driving condition and the intermediate driving condition of the device are generally different from each other, it is necessary to cope with such driving condition efficiently.

However, since the conventional battery pack is composed of one type of battery module (a mechanical and electrical connection body of the same type of unit cells), it has a limitation that it can not efficiently cope with the various driving conditions.

In addition, since it is substantially impossible to manufacture a battery exhibiting satisfactory performance in all situations, it is usually necessary to take measures to deteriorate other characteristics in order to improve one characteristic.

In particular, this problem is most problematic at startup of the device at low temperatures. The high temperature problem is generally due to the fact that a separate cooling system is installed even for the heat of the cell itself. This is because, even at a low temperature, it is driven in a state where the temperature is no longer a low temperature condition due to heat generation of the cell itself after startup.

In order to perform low-temperature start-up, when the battery pack is constructed by a single cell having excellent low-temperature characteristics as in the prior art, all other performance deterioration must be avoided.

Considering this point, there is an urgent need to develop a new concept battery pack which can be applied to a system requiring complex characteristics and has improved low-temperature starting performance.

Accordingly, efforts to solve such a problem have been consistently made in the related field, and the present invention has been made based on this technical background.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to provide a battery pack which can operate smoothly at a low-temperature start-up and minimize the degree of deterioration or degradation of the entire capacity and other performance by combining battery cells of different kinds.

In order to achieve the above object, the present invention provides a battery pack including a plurality of battery cells electrically connected to each other, wherein a battery cell (A) of 10% or less based on the total number of battery cells has a low temperature performance And the battery cell (A) includes a composition in which the electrode and / or the electrolyte exhibits low-temperature high-output characteristics.

The battery cell A may be 10% or less, preferably 0.5 to 10%, and more preferably 1 to 5% based on the total number of the battery cells.

In one preferred example of the present invention, the battery cell (A) may contain a sulfonyl group-containing imide lithium compound as an additive in the cell.

In another example, the battery cell (A) may contain an inorganic salt represented by the following formula (1) as an additive in the cell.

R ₄ X ⁺ YZ _n ^- (1)

In this formula,

R is C ₃ -C ₁₀ alkyl;

X is nitrogen or phosphorus;

Y is boron or phosphorus;

Z is C ₃ -C ₁₀ alkyl, C ₄ -C ₁₀ cyclo or aromatic, or halogen;

n is 4 or 6 due to the oxidation number of Y according to the selection of X and Y. [

Preferably, the battery cell (A) is made of propylene carbonate (PC) or a mixed solvent of PC and linear carbonate as an electrolyte solution in the electrolyte, and the linear carbonate is a mixture of diethyl carbonate (DEC) and dimethyl carbonate And may be one or more selected from the group consisting of

The battery cell (A) may preferably use a non-black carbon material as a negative electrode active material, and the non-black carbon material preferably contains non-graphitized carbon of 50% or more by weight.

The electrolyte composition and the electrode configuration as described above can be said to be a particularly preferable combination for the low temperature high output characteristic of the battery cell (A).

In one preferred embodiment, the battery cell A is connected to the external input / output terminal in series and / or in parallel with the battery cell B by a single circuit, or the battery cell A is connected to the battery cells B, It may be electrically separated and connected to the external input / output terminal by a separate circuit.

The present invention also provides a device including the battery pack as a power source.

The device comprising: a power tool powered by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart, or a system for power storage.

In one preferred example, the device is an electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle, and the battery cell A is connected to the starter by a separate circuit.

As described above, since the battery cell A having excellent low-temperature performance is constituted by combining 10% or less based on the total number of the battery cells, the battery pack according to the present invention has excellent low-temperature characteristics, As much as possible.

Hereinafter, the present invention will be described in more detail.

As described above, according to the present invention, a plurality of battery cells are electrically connected to each other, and a battery cell (A) of 10% or less based on the total number of battery cells has a low temperature performance And the battery cell (A) includes a composition in which an electrode and / or an electrolyte exhibit low-temperature high-output characteristics.

When starting the device, the required output is high, but the amount of energy required is not large. That is, it is not necessary to start all the battery cells for starting. That is, since it is possible to start the battery cell A only with a part of the battery cells A, when the battery cell A is combined with the battery cells having excellent low temperature performance as compared with the remaining battery cells B, Performance and various driving conditions can be satisfied.

The battery cell A needs to be set to 10% or less as described above based on the total number of battery cells. It has been confirmed by the inventors of the present application that if the number of battery cells A exceeds the above range, the low-temperature characteristics are increased, but the reaction of reducing the capacity of the battery pack as a whole is relatively large Respectively.

The high and low temperatures of the low temperature output characteristics are not particularly limited as they are relative concepts.

Each of the secondary battery cells (unit cells) constituting the battery pack may be various, and may be preferably a lithium secondary battery. The lithium secondary battery can control the low temperature output characteristics by various factors such as the constitution of the positive electrode active material and / or the negative electrode active material, the type of the electrolyte, the presence or absence of the additive, and accordingly, the low temperature high output battery cell can be easily manufactured.

The lithium secondary battery has a structure in which a non-aqueous electrolyte solution containing a lithium salt is impregnated in an electrode assembly having a separator interposed between an anode and a cathode.

The positive electrode may be formed by applying, drying and applying a positive electrode active material on a positive electrode current collector, for example, and may further include components such as a binder, a conductive material, and the like selectively.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and may be formed of a material such as stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel Treated with carbon, nickel, titanium, silver or the like may be used. The positive electrode current collector may have fine unevenness formed on the surface thereof to increase the adhesive force of the positive electrode active material as in the case of the negative electrode current collector. Alternatively, the positive electrode current collector may have various properties such as a film, sheet, foil, net, porous body, Form is possible.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0 .4 Mn 0 .4 Co 0 .2 O 2 Li , such as _{1 + z Ni b Mn c Co} 1 - _{(b + c + d)} M _d O _(2-e) A _e B + c &lt; = 0.8, 0.1? C? 0.8, 0? D? 0.2, 0? E? 0.2, b + c + d <1, M = Al, Mg, Cr , Ti, Si or Y and A = F, P or Cl); And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

The binder may include a binder in an amount of 1 to 20% by weight, and may optionally include a conductive material in a range of 0 to 20% by weight based on the total weight of the electrode mixture applied to the current collector.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, various copolymers, high molecular weight polyolefins such as polyolefin, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, Vinyl alcohol, and the like.

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. Concrete examples of commercially available conductive materials include acetylene black series such as Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, etc.), Ketjenblack, EC (Armak Company), Vulcan XC-72 (Cabot Company), and Super P (Timcal).

In some cases, a filler may be optionally added as a component for suppressing the expansion of the electrode. Such a filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and examples thereof include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

In addition, other components such as a viscosity adjusting agent, an adhesion promoter and the like may be further included as a selective or a combination of two or more.

The viscosity adjusting agent may be added up to 30% by weight based on the total weight of the electrode mixture, so as to control the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the collector may be easy. Examples of such viscosity modifiers include carboxymethylcellulose, polyvinylidene fluoride and the like, but are not limited thereto. In some cases, the above-described solvent may play a role as a viscosity adjusting agent.

The adhesion promoter may be added in an amount of 10% by weight or less based on the binder, for example, oxalic acid, adipic acid, Formic acid, acrylic acid derivatives, itaconic acid derivatives, and the like.

The negative electrode is manufactured by coating a negative electrode material on a negative electrode collector and drying the same, and if necessary, may further include components such as a conductive material and a binder as described above.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

Examples of the negative electrode active material include carbon and graphite materials such as natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene and activated carbon; Metals such as Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt and Ti which can be alloyed with lithium and compounds containing these elements; Complexes of metals and their compounds and carbon and graphite materials; Lithium-containing nitrides, and the like. Among them, a carbon-based active material, a silicon-based active material, a tin-based active material, or a silicon-carbon based active material is more preferable, and these may be used singly or in combination of two or more.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous electrolytic solution include n-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, Nitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives , Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. are added It is possible. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene carbonate, PRS (propene sultone), FPC (fluoro-propylene carbonate), and the like.

In the present invention, the battery cells (A) may further include additives in the cells to exhibit low-temperature characteristics. The additives are not limited as long as they improve the low-temperature performance.

One example of the additive is a lithium mixed salt composed of a lithium salt for a lithium secondary battery and a sulfonyl group-containing imide lithium compound.

LiPF ₆ used as a lithium salt for a non-aqueous electrolyte conventionally has a problem that the degree of low-temperature dissociation is lowered. That is, there is a problem that the dissociation degree of lithium ions and PF ₆ anions is lowered at a low temperature and the battery resistance is rapidly increased. On the other hand, when the sulfonyl group-containing imide lithium compound is added to the electrolytic solution together with the sulfonium group-containing imide lithium compound, the association with the lithium ion is low even at a low temperature due to its large anion size, so that lithium ions are easily dissociated from the anion, It is possible to smoothly move between the anode and the cathode. Therefore, the low-temperature resistance of the lithium ion secondary battery is reduced, thereby improving the low-temperature output characteristics.

As described above, the "sulfonyl group-containing imide lithium compound" is not particularly limited as long as it is a compound having a structure in which small lithium ions are coordinated to an anion group having a large size. Lithium bis (Trifluoromethanesulfonyl) (perfluoroethylsulfonyl) imide (BETI), lithium bis [(perfluoroalkyl) sulfonyl] imide, lithiumpoly [4,4'- (hexafluoroisopropylidene) diphenoxy] sulfonylimide (LiPHFIPSI) Or a combination thereof. Among them, Lithium bis (Trifluoromethanesulfonyl) imide ('LiTFSI') salt having a stable high-temperature storage and cycle characteristics as well as low-temperature performance is particularly preferable.

The content of the compound is preferably 10% to 60%, more preferably 30% to 40%, based on the total weight of the electrolytic solution. If the content is less than the above range, it is difficult to expect the effect of the addition, that is, the improvement of the low-temperature characteristics. On the contrary, if it is more than the above range, the viscosity of the electrolytic solution becomes high and the electric conductivity becomes low.

According to the present invention, other lithium salts constituting the lithium mixed salt together with the sulfonyl group-containing imide lithium compound may be lithium salts known in the art. Examples thereof include LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi , Chloroborane lithium, lower aliphatic carboxylate lithium, lithium 4-phenylborate, and the like, among which LiPF ₆ is particularly preferable.

Another example of the additive is an inorganic salt represented by the following general formula (1).

R ₄ X ⁺ YZ _n ^- (1)

Wherein, R is C ₃ -C ₁₀ alkyl; X is nitrogen or phosphorus; Y is boron or phosphorus; Z is C ₃ -C ₁₀ alkyl, C ₄ -C ₁₀ cyclo or aromatic, or halogen; n is 4 or 6 due to the oxidation number of Y according to the selection of X and Y. [

The inorganic salt of Formula 1 has a high degree of dissociation in the electrolyte solvent, and dissociated cations and anions do not react with the positive and negative electrodes in the lithium battery, and form a charge double layer at the interface between the positive and negative electrodes. That is, the compound of formula (I) may generate a charge double layer at the interface between the positive electrode and the negative electrode during charging / discharging at a low temperature to improve the reactivity between the Li ion and the electrode, thereby reducing the resistance of the electrode interface and thereby improving the output performance . According to the experiment, it was confirmed that a resistance reduction of about 40% or more and an output increase of 40% or more were obtained at a low temperature of -20 to -30 占 폚 as compared with the conventional lithium secondary battery.

In the above formula (1), R is preferably an alkyl having 3 to 10 carbon atoms, more preferably butyl.

Especially preferred examples of the inorganic salt of the formula (1) _{(C 4 H 9) 4 NB} (C 4 H 9) 4, (C 4 H 9) 4 NBF 4, (C 4 H 9) 4 NB (C 6 H 5 ) ₄ , (C ₄ H ₉ ) ₄ NPF _6, and (C ₄ H ₉ ) ₄ PBF ₄ .

The inorganic salt of Formula 1 is preferably added in an amount of 0.1 to 20% by weight based on the total weight of the electrolytic solution. If the addition amount is too small, it is difficult to obtain the effect of the addition. On the other hand, if it is too much, the viscosity of the electrolytic solution increases and the internal resistance increases.

In one preferred embodiment, the battery cells (A) use a mixed solvent containing linear carbonates such as diethyl carbonate (DEC) and dimethyl carbonate (DMC) in addition to propylene carbonate (PC) .

The PC is preferable to a material of a battery which requires operation at a low temperature since it has characteristics of low freezing point compared to ethylene carbonate (EC).

In another preferred example, the battery cells (A) can use a non-black carbon material as the negative electrode active material. The term "non-black carbon material" as used herein refers to a case where at least 50% of the non-black carbon material is contained and can not be regarded as a graphite carbon material.

As a more preferable example, the graphite carbon material may be a negative electrode material comprising 50% or more of non-graphitized carbon in a weight ratio.

Graphite and graphitized carbon mainly use ethylene carbonate (EC) as an electrolyte solvent due to the characteristics of the material in a lithium secondary battery, whereas non-graphitized carbon can use propylene carbonate (PC) as an electrolyte solvent, The characteristics can be improved.

In the present invention, the battery cells A may be connected to the external input / output terminals by a single circuit in series and / or in parallel with the battery cells B.

On the other hand, the battery cells A may be electrically separated from the battery cells B and connected to the external input / output terminals through separate circuits. In this case, the battery cells A may be connected to the external input / output terminals at the time of initial startup, and the battery cells B may be connected to the external input / output terminals after the startup. To this end, a separate switch may be required and the switch may be included in the circuit system.

The present invention also provides a device including the battery pack as a power source.

Preferred examples of such devices include: a power tool powered by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system.

In one preferred embodiment, the device may be an electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle, and the battery cells A may be connected to the starter device as a separate circuit.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (14)

A plurality of battery cells are electrically connected,
The battery cell A having a capacity of 10% or less based on the total number of battery cells is superior in low temperature performance to the remaining battery cells B,
The battery cell (A) comprises a sulfonyl group-containing imide lithium compound or an inorganic salt represented by the following formula (1) as an additive in the cell so that the electrode and / or the electrolyte exhibit low-temperature high-
Wherein the battery cell (A) uses propylene carbonate (PC) or a mixed solvent of PC and linear carbonate as an electrolyte solution in the electrolyte .
R ₄ X ⁺ YZ _n ^- (1)
In this formula,
R is C ₃ -C ₁₀ alkyl;
X is nitrogen or phosphorus;
Y is boron or phosphorus;
Z is C ₃ -C ₁₀ alkyl, C ₄ -C ₁₀ cyclo or aromatic, or halogen;
N is 4 or 6 due to the oxidation number of Y according to the selection of X and Y. [ The battery pack according to claim 1, wherein the battery cell (A) comprises 0.5 to 10% based on the total number of battery cells. The battery pack according to claim 1, wherein the battery cell (A) comprises 1 to 5% based on the total number of battery cells. delete delete delete The battery pack according to claim 1, wherein the linear carbonate is at least one selected from the group consisting of diethyl carbonate (DEC) and dimethyl carbonate (DMC). The battery pack according to claim 1, wherein the battery cell (A) uses a non-black carbon material as the negative electrode active material. The battery pack according to claim 8, wherein the graphite carbon material comprises at least 50% by weight of non-graphitized carbon. The battery pack according to claim 1, wherein the battery cell (A) is connected to the external input / output terminal in series and / or in parallel with the battery cell (B) by a single circuit. The battery pack according to claim 1, wherein the battery cell (A) is electrically separated from the battery cell (B) and connected to an external input / output terminal by a separate circuit. 10. A device comprising the battery pack according to claim 1 as a power source. 13. The apparatus of claim 12, wherein the device comprises: a power tool powered by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart, or a system for power storage. 14. The device according to claim 13, wherein the device is an electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle, and the battery cell (A) is connected to the starting device as a separate circuit.