Battery module and refrigerant composition

Abstract

To provide a battery module and a refrigerant composition with good cooling / heating performance for batteries. [Solution] A battery module comprising a battery and a thermal management unit that performs thermal management of the battery, wherein the thermal management unit comprises a refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)).

Description

[Technical Field]

[0001] This disclosure relates to a battery module and a refrigerant composition. [Background technology]

[0002] Refrigerants containing 2,3,3,3-tetrafluoropropene (R-1234yf) or 1,1-difluoroethylene (R-1132a) are known to be used for cooling batteries in electric vehicles (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 2022-538483 [Patent Document 2] Special Publication No. 2023-513332 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure aims to provide a battery module and a refrigerant composition that have good cooling / heating performance for batteries. [Means for solving the problem]

[0005] (1) The present disclosure is a battery module comprising a battery and a thermal management unit for performing thermal management of the battery, wherein the thermal management unit comprises a refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)).

[0006] Disclosure (2) is a battery module according to Disclosure (1), wherein the thermal management method is a direct expansion type or a secondary loop type.

[0007] Disclosure (3) is a battery module according to Disclosure (1) or (2), wherein the R-1132(E) content is 1 to 70% by mass relative to the refrigerant composition.

[0008] Disclosure (4) is a battery module in any combination of any of Disclosures (1) to (3) wherein the R-1132(E) content is 20 to 70% by mass relative to the refrigerant composition.

[0009] Disclosure (5) is a battery module in any combination of any of Disclosures (1) to (4) wherein the refrigerant composition further includes a refrigerant whose boiling point difference with R-1132(E) is 35°C or less.

[0010] Disclosure (6) is a battery module in any combination of any of Disclosures (1) to (5) wherein the refrigerant composition further comprises at least one refrigerant selected from the group consisting of 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze), 1,1-difluoroethane (R-152a), difluoromethane (R-32), propane (R-290), and carbon dioxide (R-744).

[0011] Disclosure (7) is a battery module in any combination of any of Disclosures (1) to (6), wherein the boiling point of the refrigerant composition is -80 to -35°C.

[0012] Disclosure (8) is a battery module in any combination of any of Disclosures (1) to (7) wherein the global warming potential (GWP) of the refrigerant composition is less than 150.

[0013] Disclosure (9) is a battery module in any combination of the refrigerant composition of any of Disclosures (1) to (8), wherein the refrigerant composition is weakly flammable, slightly flammable, or non-flammable.

[0014] Disclosure (10) is a battery module in any combination of any of Disclosures (1) to (9) wherein the capacity of the battery is 10 kWh or more.

[0015] Disclosure (11) is a battery module in any combination with any of Disclosures (1) to (10), wherein the battery is a lithium-ion secondary battery.

[0016] Disclosure (12) is a battery module in any combination with any of Disclosures (1) to (11) which are for electric vehicles or hybrid vehicles.

[0017] This disclosure (13) is a refrigerant composition comprising trans-1,2-difluoroethylene (R-1132(E)) used for thermal management of batteries.

[0018] This disclosure (14) is a refrigerant composition according to this disclosure (13), wherein the R-1132(E) content is 20 to 70% by mass relative to the refrigerant composition.

[0019] The present disclosure (15) further comprises a refrigerant composition according to the present disclosure (13) or (14), wherein the battery is a lithium-ion secondary battery, and further comprises at least one refrigerant selected from the group consisting of 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze), 1,1-difluoroethane (R-152a), difluoromethane (R-32), propane (R-290), and carbon dioxide (R-744). [Effects of the Invention]

[0020] According to this disclosure, it is possible to provide a battery module and a refrigerant composition that have good cooling / heating performance for the battery. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic diagram of an experimental apparatus used to determine flammability (combustibility or non-combustibility). [Modes for carrying out the invention]

[0022] The following provides a detailed explanation of this disclosure.

[0023] This disclosure relates to a battery module comprising a battery and a thermal management unit that performs thermal management of the battery, wherein the thermal management unit comprises a refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)).

[0024] The battery module of this disclosure, by comprising a specific refrigerant composition, exhibits good cooling / heating performance (e.g., cooling / heating capacity and efficiency). Therefore, the time required for temperature control of the battery can be reduced. Note that "cooling / heating performance" refers to both cooling performance and / or heating performance.

[0025] The battery module of this disclosure can also achieve good levels of cooling / heating performance (refrigeration capacity, heating capacity, temperature glide, temperature control time) while maintaining acceptable levels of global warming potential (GWP) and flame retardancy.

[0026] The batteries described herein include batteries whose handling and performance may deteriorate at high and / or low temperatures, and secondary batteries are preferred, with alkali metal ion secondary batteries and alkaline earth metal ion secondary batteries being more preferred. Examples of the above-mentioned secondary batteries include lithium-ion secondary batteries, sodium-ion secondary batteries, potassium-ion secondary batteries, and magnesium-ion secondary batteries, with lithium-ion secondary batteries and sodium-ion secondary batteries being preferred.

[0027] The above-mentioned battery is preferably high-capacity, more preferably 10kWh or more, even more preferably 30kWh or more, and even more preferably 60kWh or more. There is no upper limit, but for example it may be 200kWh, 150kWh, or 100kWh. For high-capacity batteries, temperature control is particularly important in terms of performance and handling, and the effects of using the above-mentioned refrigerant composition can be significantly demonstrated.

[0028] Details of the battery configurations that can be used in this disclosure will be described later.

[0029] The thermal management unit in this disclosure performs the thermal management of the battery as described above. Here, thermal management of the battery means managing heat in order to maintain the battery within an appropriate temperature range, in particular, cooling or heating the battery.

[0030] The thermal management method is not limited, but is preferably a direct expansion type or a secondary loop type, and more preferably a direct expansion type. The battery module of this disclosure enables efficient temperature control of the battery even if it is a direct expansion type. Furthermore, when a secondary loop type is adopted, it may be a direct AC type or a countercurrent type, but a countercurrent type is preferred. The above-mentioned thermal management unit may include a heat exchanger.

[0031] The thermal management unit described above comprises a refrigerant composition containing R-1132(E). The above refrigerant composition may contain at least R-1132(E) as a refrigerant component. In this specification, the term "refrigerant" includes at least compounds that have been assigned a refrigerant number (ASHRAE number) beginning with R, as defined by ISO 817 (International Organization for Standardization), and also includes compounds that have equivalent refrigerant properties even if they have not yet been assigned a refrigerant number.

[0032] Containing R-1132(E) means that the R-1132(E) content in the refrigerant composition is 0.1% by mass or more. The R-1132(E) content is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and also preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. The R-1132(E) content can be set according to the combination of components contained in the refrigerant composition, as long as a disproportionation reaction does not occur.

[0033] The above refrigerant composition may further contain refrigerants other than R-1132(E), and may be a mixed refrigerant. The above refrigerant composition is preferably further comprising a refrigerant whose boiling point difference with R-1132(E) is 35°C or less, more preferably comprising a refrigerant whose boiling point difference with R-1132(E) is 30°C or less, and even more preferably comprising a refrigerant whose boiling point difference with R-1132(E) is 25°C or less, in terms of the cooling / heating performance of the battery. The above refrigerant composition is particularly preferably one that contains a refrigerant having a higher boiling point than R-1132(E) and whose boiling point difference from R-1132(E) is within the range described above. The boiling point of a refrigerant is the temperature at which its vapor pressure reaches 1 atmosphere (atm), and can be determined from the vapor pressure curve. The boiling point of R-1132(E) is -52.5°C.

[0034] Other refrigerants besides R-1132(E) include 2,3,3,3-tetrafluoropropene (R-1234yf, boiling point: -29.4℃), trans-1,3,3,3-tetrafluoropropene (R-1234ze, boiling point: -19℃), 1,1-difluoroethane (R-152a, boiling point: -24℃), difluoromethane (R-32, boiling point: -51.7℃), propane (R-290, boiling point: -42℃), carbon dioxide (R-744, boiling point: -78.5℃), 1,1-difluoroethylene (R-1132a, boiling point: -83℃), etc., and one or more of these can be used. In particular, at least one selected from the group consisting of R-1234yf, R-1234ze, R-152a, R-32, R-290 and R-744 is preferred, at least one selected from the group consisting of R-1234yf, R-1234ze, R-152a, R-32 and R-290 is more preferred, at least one selected from the group consisting of R-1234yf, R-152a, R-32 and R-290 is even more preferred, and at least one selected from the group consisting of R-1234yf, R-32 and R-290 is even more preferred.

[0035] The above refrigerant composition preferably includes, for example, R-1132(E) and R-1234yf. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E) and R-1234yf is preferably 12 to 70% by mass, more preferably 20% or more by mass, more preferably 50% or less by mass, and even more preferably 35% or less by mass. In the above combinations, it is particularly preferable that the proportion of R-1132(E) is 23±2 mass% and the proportion of R-1234yf is 77±2 mass% relative to the total mass of R-1132(E) and R-1234yf, and it is also preferable that the proportion of R-1132(E) is 31.5±2 mass% and the proportion of R-1234yf is 68.5±2 mass%.

[0036] The above refrigerant composition may also preferably contain R-1132(E), R-32, and R-1234yf. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E), R-32, and R-1234yf is preferably 10 to 30% by mass, and more preferably 20% by mass or more. Furthermore, the proportion of R-32 to the total mass of R-1132(E), R-32, and R-1234yf is preferably 15 to 50% by mass, more preferably 18% by mass or more, and even more preferably 48% by mass or less. Furthermore, the proportion of R-1234yf to the total mass of R-1132(E), R-32, and R-1234yf is preferably 20 to 60% by mass, more preferably 25% or more by mass, and even more preferably 55% or less by mass. In the above combinations, it is particularly preferable that the proportion of R-1132(E) is 28±2 mass%, the proportion of R-32 is 21.5±2 mass%, and the proportion of R-1234yf is 50.5±2 mass%, relative to the total mass of R-1132(E), R-32, and R-1234yf. It is also preferable that the proportion of R-1132(E) is 25±2 mass%, the proportion of R-32 is 44±2 mass%, and the proportion of R-1234yf is 31±2 mass%.

[0037] The above refrigerant composition may also preferably contain R-1132(E) and R-152a. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E) and R-152a is preferably 12 to 70% by mass, more preferably 20% by mass or more, even more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 50% by mass or less, and even more preferably 40% by mass or less. In the above combination, it is particularly preferable that the proportion of R-1132(E) is 35±2 mass% and the proportion of R-152a is 65±2 mass% relative to the total mass of R-1132(E) and R-152a.

[0038] The above refrigerant composition may also preferably contain R-1132(E) and R-290. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E) and R-290 is preferably 12 to 70% by mass, more preferably 35% by mass or more, even more preferably 45% by mass or more, even more preferably 55% by mass or more, and particularly preferably 60% by mass or more.

[0039] The above refrigerant composition may also preferably contain R-1132(E) and R-744. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E) and R-744 is preferably 12 to 70% by mass, more preferably 20% or more by mass, even more preferably 25% or more by mass, even more preferably 60% or less by mass, and even more preferably 50% or less by mass.

[0040] The above refrigerant composition may also preferably contain R-1132(E) and R-1234ze. In the above combination, the proportion of R-1132(E) to the total mass of R-1132(E) and R-1234ze is preferably 12 to 70% by mass, more preferably 15% by mass or more, more preferably 50% by mass or less, and even more preferably 35% by mass or less.

[0041] The above refrigerant composition may further contain components other than the refrigerant component, but it is preferable that it consists substantially only of the refrigerant component. "Substantially consisting only of the refrigerant component" means that the content of the refrigerant component in the refrigerant composition is 95% by mass or more. The content of the refrigerant component is preferably 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.5% by mass or more. There is no upper limit, and it may be 100% by mass.

[0042] The above refrigerant composition preferably has a boiling point of -80 to -35°C in terms of the cooling / heating performance of the battery. The boiling point of the above refrigerant composition may be -75°C or higher, -70°C or higher, -65°C or higher, or -60°C or higher, but a lower boiling point is preferable in terms of the cooling / heating performance of the battery.

[0043] The above refrigerant composition may have a global warming potential (GWP) of less than 300, preferably less than 150, more preferably less than 100, even more preferably less than 50, even more preferably less than 10, particularly preferably less than 5, and may also be 1 or more. The GWP is determined based on the values in the 4th report of the IPCC (Intergovernmental Panel on Climate Change). For refrigerants not reported by the IPCC, it is determined based on Notification No. 54 of the Ministry of Economy, Trade and Industry in 2015.

[0044] The above refrigerant composition preferably has excellent flame retardancy. Specifically, it is preferably weakly flammable, slightly flammable or non-flammable, may be weakly flammable or slightly flammable, and may also be slightly flammable. In this specification, when the refrigerant composition is "non-flammable", it means that it is judged as Class 1 in the flammability class according to the standard of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), "weakly flammable" means that it is judged as Class 2, and "slightly flammable" means that it is judged as Class 2L.

[0045] In terms of cooling performance, the refrigerating capacity in the cooling operation of the above refrigerant composition is preferably 2000 kJ / m 3 or more, more preferably 2500 kJ / m 3 or more, still more preferably 3000 kJ / m 3 or more, and may be 7000 kJ / m 3 or less, may also be 6000 kJ / m 3 or less, and may also be 4500 kJ / m 3 or less. The refrigerating capacity in the cooling operation is measured by the method described in the examples below.

[0046] In terms of heating performance, the refrigerating capacity in the heating operation of the above refrigerant composition is preferably 350 kJ / m 3 or more, more preferably 400 kJ / m 3 or more, still more preferably 500 kJ / m 3 or more, and may be 1500 kJ / m 3 or less, may also be 1000 kJ / m 3 or less, and may also be 800 kJ / m 3 or less. The refrigeration capacity during heating operation is measured by the method described in the examples below.

[0047] In terms of cooling performance, the above refrigerant composition preferably has a condensation glide of 8.5K or less during cooling operation, more preferably 7.5K or less, even more preferably 6.5K or less, even more preferably 5.5K or less, and particularly preferably 4.5K or less. It may also be 0.0K or higher, 0.5K or higher, 1.0K or higher, or 2.0K or higher.

[0048] In terms of heating performance, the above refrigerant composition preferably has a condensation glide of 7.0K or less during heating operation, more preferably 6.0K or less, even more preferably 5.0K or less, even more preferably 4.5K or less, and particularly preferably 4.0K or less. It may also be 0.0K or higher, 0.5K or higher, 1.0K or higher, or 2.0K or higher.

[0049] In terms of cooling performance, the above refrigerant composition preferably has an evaporative glide of 8.0K or less during cooling operation, more preferably 7.0K or less, even more preferably 6.0K or less, even more preferably 5.0K or less, and particularly preferably 4.0K or less. It may also be 0.0K or higher, 0.5K or higher, 1.0K or higher, or 2.0K or higher.

[0050] In terms of heating performance, the above refrigerant composition preferably has an evaporative glide of 4.0K or less during heating operation, more preferably 3.5K or less, even more preferably 2.5K or less, and may also be 0.0K or higher, 0.5K or higher, or 1.0K or higher.

[0051] In terms of cooling performance, the above refrigerant composition preferably has an average value of condensation glide and evaporation glide in cooling operation of 7.5K or less, more preferably 7.0K or less, even more preferably 6.5K or less, even more preferably 6.0K or less, even more preferably 5.5K or less, and particularly preferably 5.0K or less. It may also be 0.0K or higher, 0.5K or higher, 1.0K or higher, or 2.0K or higher.

[0052] In terms of heating performance, the above refrigerant composition preferably has an average value of condensation glide and evaporation glide in heating operation of 6.0K or less, more preferably 5.5K or less, even more preferably 5.0K or less, even more preferably 4.5K or less, and particularly preferably 4.0K or less. It may also be 0.0K or higher, 0.5K or higher, 1.0K or higher, or 2.0K or higher.

[0053] Condensation glide and evaporation glide during cooling and heating operations are measured by the method described in the examples below.

[0054] In this specification, evaporation ( / condensation) glide refers to the temperature glide during evaporation ( / condensation), and can be rephrased as the absolute value of the difference between the start temperature and the end temperature of the evaporation ( / condensation) process of the refrigerant composition within the components of a thermal cycle system.

[0055] In terms of cooling performance, the above refrigerant composition is preferably such that the ratio of R-1234yf temperature control time to R-1234yf temperature control time in cooling operation is 90% or less, more preferably 85% or less, even more preferably 75% or less, even more preferably 60% or less, and particularly preferably 55% or less. It may also be 10% or more, 20% or more, or 30% or more.

[0056] In terms of heating performance, the above refrigerant composition is preferably such that the ratio of R-1234yf temperature control time to heating operation is 90% or less, more preferably 75% or less, even more preferably 70% or less, even more preferably 60% or less, and particularly preferably 50% or less. It may also be 10% or more, 20% or more, or 30% or more.

[0057] The temperature control time during cooling and heating operations is measured by the method described in the examples below.

[0058] The battery module of this disclosure is preferably for use in a vehicle, more preferably for use in an automobile, and even more preferably for use in an electric vehicle or a hybrid vehicle. Surprisingly, it has been found that using the battery module of this disclosure in an automobile may reduce the battery load or extend the driving range. Since the battery module of this disclosure has good temperature control capabilities, it is thought that the capacity of the backup power supply for battery temperature control can be reduced, thereby reducing the overall battery load. Furthermore, by reducing the capacity of the backup power supply, the system can be miniaturized, which in turn allows for a reduction in the amount of refrigerant to be charged, thus reducing the vehicle weight (battery, chassis, brakes) and extending the driving range. The battery module of this disclosure is particularly preferably used in the drive battery of the automobile described above.

[0059] This disclosure also relates to a refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)) used in thermal management of batteries. The refrigerant composition of this disclosure contains a specific refrigerant, resulting in good cooling / heating performance of the battery (e.g., cooling / heating capacity and efficiency). Therefore, the time required for temperature control of the battery can be reduced. The refrigerant compositions of this disclosure can also provide good levels of cooling / heating performance (refrigeration capacity, heating capacity, temperature glide, temperature control time) while maintaining acceptable levels of GWP and flame retardancy.

[0060] The refrigerant composition used in this disclosure can be the same as the refrigerant composition used in the battery module of this disclosure as described above.

[0061] The batteries, thermal management systems, and applications to which the refrigerant compositions of this disclosure can be applied are similar to those of the battery modules described above.

[0062] The following describes the battery module and the batteries that can be used in the refrigerant composition of this disclosure, particularly alkali metal ion secondary batteries.

[0063] The battery in this disclosure can take a known structure and typically comprises a positive electrode and a negative electrode capable of intercepting and releasing ions (e.g., lithium ions), and an electrolyte.

[0064] The positive electrode consists of a positive electrode active material layer containing positive electrode active material and a current collector.

[0065] The positive electrode active material is not particularly limited as long as it is electrochemically capable of intercalating and releasing alkali metal ions and alkaline earth metal ions, but for example, a material containing an alkali metal and at least one transition metal is preferred. Specific examples include alkali metal-containing transition metal composite oxides, alkali metal-containing transition metal phosphate compounds, sulfur-based materials, and conductive polymers. Among these, alkali metal-containing transition metal composite oxides that produce high voltage are particularly preferred as the positive electrode active material. Examples of the alkali metal ions and alkaline earth metal ions include lithium ions, sodium ions, potassium ions, and magnesium ions. In a preferred embodiment, the alkali metal ions may be lithium ions or sodium ions. That is, in this embodiment, the alkali metal ion secondary battery is a lithium-ion secondary battery or a sodium-ion secondary battery.

[0066] Examples of the alkali metal-containing transition metal composite oxides mentioned above include: Formula: Ma Mn 2-b M 1 b O4 (wherein M is at least one metal selected from the group consisting of Li, Na, and K; 0.9 ≤ a; 0 ≤ b ≤ 1.5; M) 1 Alkali metal-manganese spinel composite oxides (such as lithium-manganese spinel composite oxides) are represented by at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge. Formula:MNi 1-c M 2 c O2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K; 0 ≤ c ≤ 0.5; M 2 (This refers to an alkali metal-nickel composite oxide (such as a lithium-nickel composite oxide) represented by at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), or Formula:MCo 1-d M 3 d O2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K; 0 ≤ d ≤ 0.5; M 3 Examples include alkali metal-cobalt composite oxides (such as lithium-cobalt composite oxides) represented by at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li.

[0067] In particular, MCoO2, MMnO2, MNiO2, MMn2O4, and MNi are used because they offer high energy density and can provide high-output secondary batteries. 0.8 Co 0.15 Al 0.05 O2, or MNi1 / 3 Co 1 / 3 Mn 1 / 3 O2 is preferred, and it is preferable that the compound is represented by the following general formula (3). MNi h Co i Mn j M 5 k O2(3) (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, M 5 (where represents at least one element selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h+i+j+k)=1.0, 0≦h≦1.0, 0≦i≦1.0, 0≦j≦1.5, and 0≦k≦0.2.)

[0068] Examples of the alkali metal-containing transition metal phosphate compounds mentioned above include the following general formula (4): M e M 4 f (PO4) g (4) (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, M 4 A compound represented by ( ) is at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni, and Cu, and satisfies 0.5 ≤ e ≤ 3, 1 ≤ f ≤ 2, and 1 ≤ g ≤ 3. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li. That is, lithium-containing transition metal phosphate compounds are preferred as the alkali metal-containing transition metal phosphate compounds.

[0069] The transition metals used in the lithium-containing transition metal phosphate compounds are preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, cobalt phosphates such as LiCoPO4, and those in which some of the transition metal atoms that make up the main body of these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si. The lithium-containing transition metal phosphate compounds are preferably those having an olivine-type structure.

[0070] Other positive electrode active materials include lithium-nickel composite oxides. The lithium-nickel composite oxide is defined by the following general formula (5): Li y Ni 1-x M x O2(5) A positive electrode active material represented by the formula (wherein x is 0.01 ≤ x ≤ 0.7, y is 0.9 ≤ y ≤ 2.0, and M represents a metal atom (excluding Li and Ni)) is preferred.

[0071] Other cathode active materials include MFePO4 and MNi 0.8 Co 0.2 O2, M 1.2 Fe 0.4 Mn 0.4 O2, MNi 0.5 Mn 1.5 Other examples include O2, MV3O6, and M2MnO3. In particular, M2MnO3 and MNi 0.5 Mn 1.5 Positive electrode active materials such as O2 are preferable because their crystalline structure does not collapse even when the secondary battery is operated at a voltage exceeding 4.4V or a voltage of 4.6V or higher. Therefore, electrochemical devices such as secondary batteries using positive electrode materials containing the positive electrode active materials exemplified above are preferable because, even when stored at high temperatures, the remaining capacity does not decrease easily, the rate of resistance increase does not change easily, and the battery performance does not deteriorate even when operated at high voltages.

[0072] Other positive electrode active materials include M2MnO3 and MM6 O2 (where M is at least one metal selected from the group consisting of Li, Na, and K, and M 6 is a transition metal such as Co, Ni, Mn, Fe, etc.). Examples also include solid solution materials with

[0073] As the above solid solution material, for example, the general formula Mx[Mn (1-y) M 7 y O z is an alkali metal manganese oxide represented by. Here, M in the formula is at least one metal selected from the group consisting of Li, Na, and K, and M 7 consists of at least one metal element other than M and Mn. For example, it contains one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr, and Sn. Also, the values of x, y, and z in the formula are in the ranges of 1 < x < 2, 0 ≤ y < 1, and 1.5 < z < 3. Among them, Li 1.2 Mn 0.5 Co 0.14 Ni 0.14 A manganese-containing solid solution material in which LiNiO2 or LiCoO2 is solid-dissolved based on Li2MnO3 such as O2 is preferable because it can provide an alkali metal ion secondary battery having a high energy density.

[0074] As the above sulfur-based material, materials containing sulfur atoms can be exemplified. At least one selected from the group consisting of elemental sulfur, metal sulfides, and organic sulfur compounds is preferable, and elemental sulfur is more preferable. The above metal sulfide may be a metal polysulfide. The above organic sulfur compound may be an organic polysulfide.

[0075] As the above metal sulfide, compounds represented by LiS x (0 < x ≤ 8); compounds represented by Li2S x (0 < x ≤ 8); compounds having a two-dimensional layered structure such as TiS2 and MoS2; compounds having a strong three-dimensional skeleton structure represented by the general formula Me x Mo6S8 (Me is various transition metals including Pb, Ag, and Cu), such as the Chevrel compound, etc.

[0076] Examples of the above-mentioned organic sulfur compounds include carbon sulfide compounds.

[0077] The above-mentioned organic sulfur compounds may be supported on a porous material such as carbon and used as a carbon composite material. The sulfur content in the carbon composite material is preferably 10 to 99% by mass, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 85% by mass or less, as this further improves cycle performance and reduces overpotential. If the positive electrode active material is elemental sulfur, the amount of sulfur contained in the positive electrode active material is equal to the amount of elemental sulfur.

[0078] Examples of conductive polymers include p-doped and n-doped conductive polymers. Other examples of conductive polymers include polyacetylene-based polymers, polyphenylene-based polymers, heterocyclic polymers, ionic polymers, ladder and network polymers, etc.

[0079] Furthermore, including lithium phosphate in the positive electrode active material is preferable because it improves continuous charging characteristics. There are no restrictions on the use of lithium phosphate, but it is preferable to use a mixture of the positive electrode active material and lithium phosphate. The amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, relative to the total amount of the positive electrode active material and lithium phosphate, with an upper limit of preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0080] Furthermore, a positive electrode active material may be used in which a substance of a different composition is attached to its surface. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0081] These surface-adhering substances can be attached to the surface of the positive electrode active material by, for example, dissolving or suspending them in a solvent and impregnating them into the positive electrode active material, followed by drying; dissolving or suspending a surface-adhering substance precursor in a solvent and impregnating it into the positive electrode active material, then reacting it by heating or other means; or adding it to the positive electrode active material precursor and simultaneously firing it. When attaching carbon, a method of mechanically attaching carbonaceous material afterwards, such as activated carbon, can also be used.

[0082] The amount of surface-adhered material is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, relative to the positive electrode active material by mass, with a lower limit of preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. The surface-adhered material can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material, thereby improving battery life. However, if the amount of adhesion is too small, the effect will not be fully realized, and if it is too large, it may hinder the movement of lithium ions in and out, potentially increasing resistance.

[0083] The particle shapes of the positive electrode active material can include conventionally used shapes such as lumpy, polyhedral, spherical, ellipsoidal, plate-like, needle-like, and columnar. Furthermore, primary particles may aggregate to form secondary particles.

[0084] The tap density of the positive electrode active material is preferably 0.5 g / cm³. 3 More preferably 0.8 g / cm³ 3 More preferably 1.0 g / cm³ 3The above is the case. If the tap density of the positive electrode active material falls below the above lower limit, the amount of dispersion medium required during the formation of the positive electrode active material layer increases, as does the amount of conductive material and binder required, which may restrict the filling rate of the positive electrode active material into the positive electrode active material layer and thus limit the battery capacity. By using a composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, a higher tap density is preferable, and there is no particular upper limit, but if it is too high, the diffusion of lithium ions using the electrolyte as a medium within the positive electrode active material layer becomes the rate-limiting step, which may lead to a decrease in load characteristics. Therefore, the upper limit is preferably 4.0 g / cm³. 3 More preferably, 3.7 g / cm³ 3 More preferably, 3.5 g / cm³ 3 The following applies: The tap density mentioned above is the powder packing density (tap density) g / cm³ obtained when 5-10 g of positive electrode active material powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of approximately 20 mm. 3 We will seek it as follows.

[0085] The median diameter d50 of the positive electrode active material particles (or secondary particle diameter if primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more. It is also preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it falls below the lower limit, it may not be possible to obtain a high-tap density product, and if it exceeds the upper limit, the diffusion of lithium within the particles will take time, which may lead to problems such as a decrease in battery performance. Here, by mixing two or more of the above positive electrode active materials having different median diameters d50, the packing performance during positive electrode fabrication can be further improved.

[0086] The median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using the HORIBA LA-920 as the particle size distribution analyzer, a 0.1% by mass aqueous solution of sodium hexametaphosphate is used as the dispersion medium, and the measurement is performed after ultrasonic dispersion for 5 minutes with the measurement refractive index set to 1.24.

[0087] When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and most preferably 2 μm or less. Exceeding the upper limit makes it difficult to form spherical secondary particles, which can adversely affect powder packing properties and significantly reduce the specific surface area, potentially leading to a decrease in battery performance such as output characteristics. Conversely, below the lower limit usually results in problems such as poor reversibility of charge and discharge due to underdeveloped crystals. The average primary particle diameter mentioned above is measured by observation using a scanning electron microscope (SEM). Specifically, it is determined by taking a 10,000x magnification photograph, finding the longest value of the intercept between the left and right boundaries of the primary particle relative to a horizontal line for any 50 primary particles, and then taking the average value.

[0088] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m². 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 The value is 1 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2 It is less than / g. If the BET specific surface area is smaller than this range, battery performance tends to decrease, and if it is larger, it becomes difficult to increase the tap density, which can cause problems with processability when forming the positive electrode active material layer. The above BET specific surface area is defined as the value measured by a single-point nitrogen adsorption BET method using a gas flow method, after pre-drying the sample at 150°C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.), and then using a nitrogen-helium mixed gas that has been precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0089] When the secondary battery of this disclosure is used as a large lithium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required, so it is preferable that the particles of the positive electrode active material consist mainly of secondary particles. Preferably, the particles of the positive electrode active material contain 0.5 to 7.0 volume percent of fine particles with an average particle diameter of 40 μm or less and an average primary particle diameter of 1 μm or less. By including fine particles with an average primary particle diameter of 1 μm or less, the contact area with the electrolyte is increased, and the diffusion of lithium ions between the electrode mixture and the electrolyte can be accelerated, thereby improving the output performance of the battery.

[0090] For the production of positive electrode active materials, general methods for producing inorganic compounds are used. In particular, various methods can be considered for producing spherical or ellipsoidal active materials. For example, a method can be used in which transition metal raw materials are dissolved or pulverized and dispersed in a solvent such as water, the pH is adjusted while stirring to produce and recover spherical precursors, these are dried as needed, and then a Li source such as LiOH, Li2CO3, or LiNO3 is added and calcined at a high temperature to obtain the active material.

[0091] For the manufacture of the positive electrode, the positive electrode active material may be used alone, or two or more materials with different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 Examples include combinations with ternary systems such as O2, combinations of LiCoO2 and LiMn2O4 or a combination in which part of the Mn is substituted with other transition metals, or combinations of LiFePO4 and LiCoO2 or a combination in which part of the Co is substituted with other transition metals.

[0092] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, and more preferably 80 to 99% by mass, in order to achieve high battery capacity. Furthermore, the content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is too low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0093] The positive electrode active material layer is preferably formed from a positive electrode mixture containing the positive electrode active material.

[0094] The above positive electrode mixture may further contain a binder, a thickener, a conductive material, etc.

[0095] As the binder mentioned above, any material can be used as long as it is safe for the components used in electrode manufacturing, for example, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, nitrocellulose; rubbery polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or its hydrogenated additive; EPDM (ethylene Examples include thermoplastic elastomer polymers such as propylene-diene terpolymer, styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, or hydrogenated versions thereof; soft resin-like polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymer, and tetrafluoroethylene-ethylene copolymer; and polymer compositions having ionic conductivity for alkali metal ions (especially lithium ions). These may be used individually or in any combination and ratio of two or more types.

[0096] The binder content is typically 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, as a percentage of the binder in the positive electrode active material layer, and is typically 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and most preferably 10% by mass or less. If the binder content is too low, the positive electrode active material cannot be sufficiently held, resulting in insufficient mechanical strength of the positive electrode and potentially degrading battery performance such as cycle characteristics. On the other hand, if it is too high, it may lead to a decrease in battery capacity and conductivity.

[0097] Examples of the thickening agents mentioned above include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, starch oxide, phosphated starch, casein, polyvinylpyrrolidone, and salts thereof. One of these may be used alone, or two or more may be used in any combination and ratio.

[0098] The ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and usually within the range of 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If it is below this range, the coating properties may be significantly reduced. If it is above this range, the proportion of active material in the positive electrode active material layer will decrease, which may lead to problems such as a decrease in battery capacity or an increase in resistance between positive electrode active materials.

[0099] Any known conductive material can be used as the conductive material mentioned above. Specific examples include metallic materials such as copper, nickel, and gold; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon materials such as needle coke, carbon nanotubes, fullerenes, and amorphous carbon such as VGCF. These materials may be used individually or in any combination and ratio of two or more materials.

[0100] The conductive material is typically contained in the positive electrode active material layer in an amount of 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and typically 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0101] When the above positive electrode mixture is made into a slurry, there are no particular restrictions on the type of solvent used to form the slurry, as long as it is capable of dissolving or dispersing the positive electrode active material, conductive material, binder, and thickener used as needed. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and a mixture of alcohol and water. Examples of organic solvents include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide.

[0102] The above positive electrode mixture may further contain a thermoplastic resin. Examples of thermoplastic resins include polyvinylidene fluoride, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and polyethylene oxide. One type may be used alone, or two or more types may be used in any combination and ratio.

[0103] The ratio of thermoplastic resin to positive electrode active material is typically 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and typically within the range of 3.0% by mass or less, preferably 2.5% by mass or less, and more preferably 2.0% by mass or less. Adding thermoplastic resin can improve the mechanical strength of the electrode. If the ratio exceeds this range, the proportion of electrode active material in the electrode mixture decreases, which may lead to problems such as a decrease in battery capacity or an increase in resistance between active materials.

[0104] Suitable materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or their alloys; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0105] Examples of current collector shapes include metal foil, metal cylinders, metal coils, metal plates, expanded metal, punched metal, and foamed metal in the case of metal materials, and carbon plates, carbon thin films, and carbon cylinders in the case of carbon materials. Of these, metal foil is preferred. The metal foil may be formed into a mesh shape as appropriate. The thickness of the metal foil is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the metal foil is thinner than this range, it may lack the necessary strength as a current collector. Conversely, if the metal foil is thicker than this range, its handling may be impaired.

[0106] Furthermore, roughening the surface of the current collector is also preferable from the viewpoint of improving the adhesion between the current collector and the positive electrode active material layer and reducing electrical contact resistance. The surface roughness of the current collector, expressed as Sa (arithmetic mean height), is preferably about 260 nm or more, more preferably about 280 nm or more, and even more preferably about 300 nm or more.

[0107] Furthermore, it is preferable that a conductive additive is applied to the surface of the current collector, as this reduces the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of conductive additives include carbon and precious metals such as gold, platinum, and silver. Carbon is particularly preferred because of its low weight.

[0108] The thickness of the positive electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer, after subtracting the thickness of the metal foil of the current collector, is preferably 10 μm or more, more preferably 20 μm or more, and preferably 500 μm or less, and more preferably 450 μm or less, as a lower limit for one side of the current collector.

[0109] The ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is preferably 20 or less, more preferably 15 or less, most preferably 10 or less, and also preferably 0.5 or more, more preferably 0.8 or more, most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heating during high current density charging and discharging. If it falls below this range, the volume ratio of the current collector to the positive electrode active material increases, which may reduce the battery capacity.

[0110] The positive electrode can be manufactured by conventional methods. For example, the positive electrode active material can be mixed with the aforementioned binder, thickener, conductive material, solvent, etc., to form a slurry-like positive electrode mixture, which can then be applied to a current collector, dried, and pressed to increase its density. This density increase can be achieved by hand pressing, roller pressing, or the like. Another method involves adding the aforementioned binder, conductive material, etc., to the positive electrode active material to prepare a positive electrode mixture sheet, laminating the positive electrode mixture sheet and the current collector via an adhesive, and then vacuum drying them.

[0111] The density of the positive electrode active material layer is preferably 1.0 g / cm³. 3 More preferably 1.3 g / cm³ 3 More preferably 1.5 g / cm³ 3 The above is true, and preferably 5 g / cm³ 3 More preferably, 3.80 g / cm³ 3 The following range applies. Exceeding this range reduces the penetration of the electrolyte near the current collector / active material interface, which can lead to decreased charge / discharge characteristics, especially at high current densities, and may prevent high output from being achieved. It can also increase the likelihood of cracking within the positive electrode active material layer. Conversely, below the above range, the conductivity between active materials decreases, increasing battery resistance and potentially preventing high output from being achieved.

[0112] From the viewpoint of enhancing high output and stability at high temperatures, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case. Specifically, it is preferable that the total electrode area of the positive electrode with respect to the surface area of the outer package of the secondary battery is 15 times or more, and more preferably 40 times or more in terms of area ratio. The outer surface area of the battery outer case refers to the total area calculated from the dimensions of the length, width, and thickness of the case portion filled with the power generation element excluding the protruding portions of the terminals in the case of a bottomed rectangular shape. In the case of a bottomed cylindrical shape, it is the geometric surface area approximated by treating the case portion filled with the power generation element excluding the protruding portions of the terminals as a cylinder. The total electrode area of the positive electrode refers to the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material. In a structure in which the positive electrode mixture layers are formed on both sides via a current collector foil, it refers to the sum of the areas calculated separately for each surface.

[0113] Also, a material with a composition different from this may be used on the surface of the positive electrode. Examples of the surface-attached substance include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0114] The negative electrode is composed of a negative electrode active material layer containing a negative electrode active material and a current collector.

[0115] The negative electrode active material is not particularly limited. For example, metal materials such as lithium metal; carbonaceous materials such as artificial graphite, graphite carbon fiber, resin-fired carbon, thermally decomposed vapor-phase grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-phase grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; alkali metal-containing metal composite oxide materials such as Li4Ti5O 12 and conductive polymers. These may be used alone or in any combination of two or more. In particular, materials containing at least a portion of carbonaceous material, or silicon-containing compounds, can be used with utmost preference.

[0116] The above-mentioned negative electrode active material preferably contains silicon as a constituent element. By including silicon as a constituent element, a high-capacity battery can be manufactured.

[0117] Preferred silicon-containing materials include silicon particles, particles having a structure in which silicon fine particles are dispersed in a silicon-based compound, silicon oxide particles represented by the general formula SiOx (0.5 ≤ x ≤ 1.6), or mixtures thereof. Using these materials makes it possible to obtain a negative electrode mixture for lithium-ion secondary batteries that has higher initial charge-discharge efficiency, higher capacity, and excellent cycle characteristics.

[0118] In this disclosure, silicon oxide refers to a general term for amorphous silicon oxides, and silicon oxide before disproportionation is represented by the general formula SiOx (0.5 ≤ x ≤ 1.6). x is preferably 0.8 ≤ x < 1.6, and more preferably 0.8 ≤ x < 1.3. This silicon oxide can be obtained, for example, by heating a mixture of silicon dioxide and metallic silicon to produce silicon monoxide gas, which is then cooled and precipitated.

[0119] Particles having a structure in which silicon nanoparticles are dispersed in a silicon-based compound can be obtained, for example, by calcining a mixture of silicon nanoparticles and a silicon-based compound, or by heat-treating silicon oxide particles before disproportionation, represented by the general formula SiOx, in an inert, non-oxidizing atmosphere such as argon at a temperature of 400°C or higher, preferably 800-1,100°C, to carry out a disproportionation reaction. The material obtained by the latter method is particularly preferable because the silicon microcrystals are uniformly dispersed. Through the disproportionation reaction described above, the size of the silicon nanoparticles can be made to 1-100 nm. It is desirable that the silicon oxide in the particles having a structure in which silicon nanoparticles are dispersed in silicon oxide is silicon dioxide. Furthermore, it can be confirmed by transmission electron microscopy that silicon nanoparticles (crystals) are dispersed in amorphous silicon oxide.

[0120] The physical properties of silicon-containing particles can be appropriately selected depending on the target composite particle. For example, the average particle size is preferably 0.1 to 50 μm, the lower limit is more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and even more preferably 20 μm or less. The above average particle size is expressed as the weight-average particle size measured by the particle size distribution method using laser diffraction.

[0121] BET specific surface area is 0.5-100m 2 / g is preferred, 1 to 20m 2 / g is more preferable. BET specific surface area is 0.5m² 2 If the value is 1 / g or higher, there is no risk of reduced adhesion when the electrodes are processed, which could lead to a decrease in battery performance. Also, 100m 2 If the value is less than / g, the proportion of silicon dioxide on the particle surface will be high, and there will be no risk of a decrease in battery capacity when used as a negative electrode material for lithium-ion secondary batteries.

[0122] By carbon coating the silicon-containing particles mentioned above, conductivity is imparted, resulting in improved battery characteristics. Methods for imparting conductivity include mixing the silicon-containing particles with conductive particles such as graphite, coating the surface of the silicon-containing particles with a carbon film, and combining both methods. However, coating with a carbon film is preferred, and chemical vapor deposition (CVD) is more preferred.

[0123] Materials containing alkali metals are also preferred as the negative electrode active material. In batteries using alkali metals as the negative electrode, temperature control is particularly important in terms of performance and handling, and the effects of using the refrigerant composition described above can be significantly demonstrated. The alkali metal mentioned above may be an elemental alkali metal. Preferably, the alkali metal is at least one selected from the group consisting of lithium, sodium, and potassium, more preferably at least one selected from the group consisting of lithium and sodium, and lithium is particularly preferred.

[0124] The content of the above-mentioned negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more, in order to increase the volume of the resulting electrode mixture. The upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less.

[0125] The above-mentioned negative electrode active material layer is preferably formed from a negative electrode mixture containing the negative electrode active material.

[0126] The above-mentioned negative electrode mixture may further contain a binder, a thickener, a conductive material, etc.

[0127] Examples of the binders mentioned above include those similar to the binders that can be used for the positive electrode as described above. The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less. If the ratio of the binder to the negative electrode active material exceeds the above range, the proportion of binder that does not contribute to the battery capacity increases, which may lead to a decrease in battery capacity. Also, if it falls below the above range, it may lead to a decrease in the strength of the negative electrode.

[0128] In particular, when a rubbery polymer such as SBR is included as the main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Furthermore, when a fluorine-based polymer such as polyvinylidene fluoride is included as the main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

[0129] Examples of the thickening agents mentioned above include those similar to the thickening agents that can be used in the positive electrode as described above. The ratio of the thickening agent to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If the ratio of the thickening agent to the negative electrode active material falls below the above range, the coating properties may be significantly reduced. If it exceeds the above range, the proportion of negative electrode active material in the negative electrode active material layer decreases, which may lead to problems such as a decrease in battery capacity or an increase in resistance between negative electrode active materials.

[0130] Examples of conductive materials for the negative electrode include metallic materials such as copper and nickel, and carbon materials such as graphite and carbon black.

[0131] When the above-mentioned negative electrode mixture is prepared as a slurry, there are no particular restrictions on the type of solvent used to form the slurry, as long as it is capable of dissolving or dispersing the negative electrode active material, binder, and any thickeners and conductive materials used as needed. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and alcohol, while examples of organic solvents include N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N,N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphoramide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, and hexane.

[0132] The above-mentioned negative electrode mixture may further contain a thermoplastic resin. Examples of thermoplastic resins include those similar to those that can be used for the positive electrode.

[0133] The ratio of thermoplastic resin to negative electrode active material is typically 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and typically within the range of 3.0% by mass or less, preferably 2.5% by mass or less, and more preferably 2.0% by mass or less. Adding thermoplastic resin can improve the mechanical strength of the electrode. If the ratio exceeds this range, the proportion of electrode active material in the electrode mixture decreases, which may lead to problems such as a decrease in battery capacity or an increase in resistance between active materials.

[0134] Suitable materials for the negative electrode current collector include metals such as copper, nickel, titanium, tantalum, and stainless steel, or their alloys; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly copper, nickel, or their alloys, are preferred.

[0135] Examples of current collector shapes include metal foil, metal cylinders, metal coils, metal plates, expanded metal, punched metal, and foamed metal in the case of metal materials, and carbon plates, carbon thin films, and carbon cylinders in the case of carbon materials. Of these, metal foil is preferred. The metal foil may be formed into a mesh shape as appropriate. The thickness of the metal foil is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the metal foil is thinner than this range, it may lack the necessary strength as a current collector. Conversely, if the metal foil is thicker than this range, its handling may be impaired.

[0136] Furthermore, roughening the surface of the current collector is also preferable from the viewpoint of improving the adhesion between the current collector and the negative electrode active material layer and reducing electrical contact resistance. The surface roughness of the current collector, expressed as Sa (arithmetic mean height), is preferably about 260 nm or more, more preferably about 280 nm or more, and even more preferably about 300 nm or more.

[0137] In addition, it is also preferable from the viewpoint of reducing the electrical contact resistance between the current collector and the negative electrode active material layer that a conductive assistant is applied to the surface of the current collector. Examples of the conductive assistant include carbon and noble metals such as gold, platinum, and silver. Carbon is particularly preferable in terms of its low weight.

[0138] The negative electrode can be manufactured by a conventional method. For example, a method can be adopted in which the above-mentioned negative electrode material is mixed with a binder, a thickener, a conductive material, a solvent, etc. to form a slurry, which is then applied to a current collector, dried, and pressed to increase its density. When using an alloy material, a method of forming a thin film layer (negative electrode active material layer) containing the above-mentioned negative electrode active material by means of techniques such as vapor deposition, sputtering, or plating can also be used. Further, a method can also be adopted in which a negative electrode mixture sheet is prepared by adding the above-mentioned binder, conductive material, etc. to the above-mentioned negative electrode active material, and the negative electrode mixture sheet and the current collector are laminated via an adhesive and then vacuum dried.

[0139] The density of the negative electrode mixture is preferably 1.0 g / cm 3 or more, more preferably 1.2 g / cm 3 or more, still more preferably 1.3 g / cm 3 or more, even more preferably 1.4 g / cm 3 or more, particularly preferably 1.5 g / cm 3 or more, and preferably 2.2 g / cm 3 or less, more preferably 2.1 g / cm 3 or less, still more preferably 2.0 g / cm 3 or less, even more preferably 1.9 g / cm 3 or less, particularly preferably 1.8 g / cm 3 within the following range. If it exceeds this range, the negative electrode active material particles may be destroyed, leading to an increase in the initial irreversible capacity and deterioration of the charge-discharge characteristics at high current density due to a decrease in the permeability of the electrolyte near the current collector / negative electrode active material interface in some cases. Also, cracks may easily occur within the negative electrode active material layer in some cases. If it is below the above range, the conductivity between the active materials may decrease, increasing the battery resistance and making it impossible to obtain high output in some cases.

[0140] The thickness of the negative electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer, after subtracting the thickness of the metal foil of the current collector, is preferably 10 μm or more, more preferably 20 μm or more, and preferably 500 μm or less, and more preferably 450 μm or less, as a lower limit for one side of the current collector.

[0141] Furthermore, a negative electrode with a different composition attached to its surface may also be used. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; and carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.

[0142] The battery in this disclosure may be a rechargeable battery using an electrolyte, or it may be a solid-state rechargeable battery. In this specification, a solid-state secondary battery may be any secondary battery containing a solid electrolyte, and may be a semi-solid secondary battery containing a solid electrolyte and a liquid component as the electrolyte, or an all-solid-state secondary battery containing only a solid electrolyte as the electrolyte.

[0143] The secondary battery using the above-mentioned electrolyte can use the same electrolyte, separator, etc. as those used in known secondary batteries. These will be described in detail below.

[0144] A non-aqueous electrolyte is preferably used as the electrolyte. As the non-aqueous electrolyte, a known electrolyte salt dissolved in a known organic solvent for dissolving electrolyte salts can be used.

[0145] The organic solvent for dissolving the electrolyte salt is not particularly limited, but one or more of the following can be used: known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorinated solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate.

[0146] Examples of electrolyte salts include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, and LiN(SO2C2F5)2. LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2, or combinations thereof are particularly preferred due to their good cycling properties.

[0147] The concentration of the electrolyte salt is preferably 0.8 mol / liter or higher, and more preferably 1.0 mol / liter or higher. The upper limit depends on the organic solvent used to dissolve the electrolyte salt, but is usually 1.5 mol / liter or lower.

[0148] A secondary battery using the above-mentioned electrolyte is preferably further equipped with a separator. The material and shape of the separator are not particularly limited as long as they are stable in the electrolyte and have excellent liquid retention properties, and known materials can be used. In particular, it is preferable to use a porous sheet or nonwoven fabric made of a material that is stable in the electrolyte, such as resin, glass fiber, or inorganic material, and has excellent liquid retention properties.

[0149] As materials for the resin and glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters can be used. These materials, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films, may be used individually or in any combination and ratio of two or more. In particular, the separator is preferably a porous sheet or nonwoven fabric made from polyolefins such as polyethylene and polypropylene, as it has good electrolyte permeability and shut-off effect.

[0150] The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulating properties and mechanical strength may decrease. If it is too thick compared to the above range, not only may the battery performance such as rate characteristics decrease, but the energy density of the electrolyte battery as a whole may decrease.

[0151] On the other hand, inorganic materials such as oxides of alumina and silicon dioxide, nitrides of aluminum nitride and silicon nitride, and sulfates of barium sulfate and calcium sulfate are used, and these are available in particulate or fibrous form.

[0152] In terms of form, thin films such as nonwoven fabrics, woven fabrics, and microporous films are used. In the thin film form, those with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the independent thin film forms described above, separators can be used in which a composite porous layer containing the inorganic particles is formed on the surface of the positive and / or negative electrode using a resin binder. For example, a porous layer can be formed on both sides of the positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0153] The material of the outer casing is not particularly limited as long as it is a stable material for the electrolyte used. Specifically, metals such as nickel-plated steel sheets, stainless steel, aluminum or aluminum alloys, magnesium alloys, or laminated films of resin and aluminum foil can be used. From the viewpoint of weight reduction, aluminum or aluminum alloys or laminated films are preferably used.

[0154] Outer cases using metals may be sealed by welding the metals together using laser welding, resistance welding, or ultrasonic welding, or by using a crimped structure with the metals connected via a resin gasket. Outer cases using laminate film may be sealed by heat-fusing the resin layers together. To improve sealing performance, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when a sealed structure is formed by heat-fusing the resin layers via a current collector terminal, since it is a joint between metal and resin, a resin having polar groups or a modified resin with introduced polar groups is preferably used as the interposing resin.

[0155] The shape of the secondary battery using the above-mentioned electrolyte is arbitrary, and examples include cylindrical, prismatic, laminated, coin-type, and large-sized shapes. The shape and configuration of the positive electrode, negative electrode, and separator can be changed and used according to the shape of each battery.

[0156] The above-mentioned solid-state secondary battery is preferably an all-solid-state secondary battery. The above-mentioned solid-state secondary battery is preferably a lithium-ion battery, and is also preferably a sulfide-based solid-state secondary battery. The above-mentioned solid-state secondary battery preferably comprises a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode.

[0157] The solid electrolyte used in the composite material for solid-state secondary batteries may be either a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, using a sulfide-based solid electrolyte has the advantage of flexibility.

[0158] The above sulfide-based solid electrolytes are not particularly limited and include Li2S-P2S5, Li2S-P2S3, Li2S-P2S3-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, LiI-Li2S-SiS2-P2S5, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li3PS4-Li4GeS4, Li 3.4 P 0.6 Si 0.4 S4, Li 3.25 P 0.25 Ge 0.76 S4, Li 4-x Ge 1-x P x S4(X=0.6~0.8), Li 4+y Ge 1-y Ga y S4(y=0.2~0.3), LiPSCl, LiCl, Li 7-x-2y PS 6-x-y Cl x (0.8≦x≦1.7, 0 <y≦-0.25x+0.5)、Li 10 SnP2S 12 Any of the following, or a mixture of two or more, can be used.

[0159] The above sulfide-based solid electrolyte preferably contains lithium. A lithium-containing sulfide-based solid electrolyte is used in solid-state batteries that use lithium ions as carriers and is particularly preferred in that it is an electrochemical device with high energy density.

[0160] The oxide-based solid electrolyte described above is preferably a compound that contains oxygen atoms (O), has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and is also an electronically insulating compound.

[0161] Specific examples of compounds include, for example, Li xa La ya TiO3 [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li xbLa yb Zr zb M bb mb O nb (M bb (The elements are Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, and xb satisfies 5 ≤ ​​xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ ​​nb ≤ 20.) , Li xc B yc M cc zc O nc (M cc (The element is C, S, Al, Si, Ga, Ge, In, Sn, and xc satisfies 0 ≤ xc ≤ 5, yc satisfies 0 ≤ yc ≤ 1, zc satisfies 0 ≤ zc ≤ 1, and nc satisfies 0 ≤ nc ≤ 6.) Li xd (Al,Ga) yd (Ti,Ge) zd Si ad P md O nd (wherein 1≦xd≦3, 0≦yd≦2, 0≦zd≦2, 0≦ad≦2, 1≦md≦7, 3≦nd≦15), Li (3-2xe) M ee xe D ee O(xe represents a number between 0 and 0.1, M ee D represents a divalent metal atom. ee ) represents a halogen atom or a combination of two or more halogen atoms. ), Li xf Si yf O zf (1≦xf≦5, 0 <yf≦3、1≦zf≦10)、Li xg S yg O zg (1 ≤ xg ≤ 3, 0 <yg≦2、1≦zg≦10)、Li3BO3-Li2SO4、Li2O-B2O3-P2O5、Li2O-SiO2、Li6BaLa2Ta2O 12 Li3PO (4-3 / 2w) N w (where w < 1), Li has a LISICON (Lithium superionic conductor) type crystal structure. 3.5 Zn 0.25La, which has a perovskite crystal structure, is GeO4. 0.51 Li 0.34 TiO 2.94 , La 0.55 Li 0.35 LiTi2P3O has a TiO3, NASICON (Natrium superionic conductor) type crystal structure. 12 Li 1+xh+yh (Al,Ga) xh (Ti,Ge) 2-xh Si yh P 3-yh O 12 (where 0≦xh≦1, 0≦yh≦1), Li7La3Zr2O has a garnet-type crystal structure. 12 Examples include (LLZ). Furthermore, ceramic materials in which elements have been substituted into LLZ are also known. For example, Li, which is partially substituted into LLZ. 6.24 La3Zr2Al 0.24 O 11.98 Li 6.25 Al 0.25 La3Zr2O 12 or Li substituted with Ta 6.6 La3Zr 1.6 Ta 0.4 O 12 Li substituted with Nb 6.75 La3Zr 1.75 Nb 0.25 O 12 Examples include the following. Other examples include LLZ-based ceramic materials in which at least one element of LLZ is substituted with Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)). Phosphorus compounds containing Li, P, and O are also desirable. Examples include lithium phosphate (Li3PO4), LiPON and LiPOD, in which some of the oxygen in lithium phosphate is substituted with nitrogen. 1 (D 1 Examples include at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. Also, LiA 1 ON(A 1(At least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used. Specific examples include Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 and Li2O-Al2O3-SiO2-P2O5-TiO2.

[0162] The above oxide-based solid electrolyte is preferably lithium-containing. A lithium-containing oxide-based solid electrolyte is used in solid-state batteries that use lithium ions as carriers and is particularly preferred in that it is an electrochemical device with high energy density.

[0163] The above oxide-based solid electrolyte is preferably an oxide having a crystalline structure. Oxides having a crystalline structure are particularly preferred in terms of good Li ion conductivity. Examples of oxides having a crystalline structure include perovskite type (La 0.51 Li 0.34 TiO 2.94 etc.), NASICON type (Li 1.3 Al 0.3 Ti 1.7 (PO4)3, garnet type (Li7La3Zr2O 12 Examples include (LLZ, etc.). Among these, the garnet type is preferred.

[0164] The volume-average particle size of oxide-based solid electrolytes is not particularly limited, but is preferably 0.01 μm or larger, and more preferably 0.03 μm or larger. The upper limit is preferably 100 μm or smaller, and more preferably 50 μm or smaller. The average particle size of oxide-based solid electrolyte particles is measured using the following procedure: A 1% by mass dispersion of oxide-based solid electrolyte particles is prepared in a 20 ml sample bottle using water (or heptane if the substance is unstable in water). The diluted dispersion sample is irradiated with 1 kHz ultrasound for 10 minutes and used immediately afterward. Using this dispersion sample, data is acquired 50 times using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA) at a temperature of 25°C using a quartz cell to obtain the volume-average particle size. For other detailed conditions, refer to JIS Z 8828:2013 "Particle Size Analysis - Dynamic Light Scattering Method" as needed. Five samples are prepared for each level, and their average value is adopted.

[0165] The above-mentioned solid-state secondary battery may include a separator between the positive electrode and the negative electrode. Examples of the separator include porous membranes such as polyethylene and polypropylene; and nonwoven fabrics such as resin nonwoven fabrics such as polypropylene and glass fiber nonwoven fabrics.

[0166] The above-mentioned solid-state secondary battery may further include a battery case. The shape of the battery case is not particularly limited as long as it can accommodate the positive electrode, negative electrode, solid electrolyte layer, etc., as described above, but specific examples include cylindrical, prismatic, coin-shaped, laminated, etc.

[0167] The above-mentioned solid-state secondary battery can be manufactured, for example, by sequentially stacking a positive electrode, a solid electrolyte layer sheet, and a negative electrode, and then pressing them together.

[0168] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Examples]

[0169] The present disclosure will now be explained with reference to examples, but the present disclosure is not limited to such examples.

[0170] Examples 1-11 and Comparative Examples 1-4 The physical properties of a battery module comprising a lithium-ion secondary battery and a direct-expansion type thermal management unit (heat exchanger) containing a refrigerant composition with the component composition shown in Tables 1-3 were measured and evaluated during cooling operation using the following method. The results are shown in Tables 1-3. Furthermore, the physical properties of the same battery module during heating operation were measured and evaluated using the following method. The results are shown in Tables 4-6.

[0171] <Boiling point after mixing> For the refrigerant composition after mixing the refrigerant components, the temperature at which the vapor pressure reaches 1 atmosphere (atm) was determined from the vapor pressure curve and was defined as the boiling point after mixing.

[0172] <Global Warming Potential (GWP)> The values ​​were determined based on those in the IPCC's Fourth Assessment Report. For refrigerants not reported in the IPCC, the values ​​were determined based on Ministry of Economy, Trade and Industry Notification No. 54 of 2015.

[0173] <Flammable Class> The composition of the refrigerant was determined by setting the WCF (Worst case of formulation for flammability) concentration, which is the most flammable composition among the permissible concentrations of refrigerants according to the US ANSI / ASHRAE 34-2013 standard, and measuring the minimum flammability concentration (LFL) and burning velocity (BV) in accordance with the ANSI / ASHRAE 34-2013 standard. Materials that do not exhibit flame propagation are classified as "Class 1 (non-combustible)," with an LFL (Luminous Fluid Level) of 0.10 kg / m³. 3 For materials with a BV of 10 cm / s or less, it is classified as "Class 2L (slightly flammable)" and has an LFL of 0.10 kg / m³. 3 For fuels with a BV (Burning Voltage) exceeding 10 cm / s, the class is "Class 2 (Low Combustion)," and the LFL (Limited Flux) is 0.10 kg / m³. 3The following were classified as "Class 3 (Highly Flammable)". In the table, "Flammable Class" refers to the result based on this classification criterion.

[0174] The combustion rate test was conducted as follows. First, the mixed refrigerant used was made 99.5% or higher in purity and degassed by repeating a cycle of freezing, pumping, and thawing until no trace of air was visible on the vacuum gauge. The combustion rate was measured using the closed method. The initial temperature was the ambient temperature. Ignition was performed by generating an electrical spark between electrodes at the center of the sample cell. The discharge duration was 1.0 to 9.9 ms, and the ignition energy was typically about 0.1 to 1.0 J. The spread of the flame was visualized using Schlieren photography. A cylindrical container (inner diameter: 155 mm, length: 198 mm) with two light-transmitting acrylic windows was used as the sample cell, and a xenon lamp was used as the light source. Schlieren images of the flame were recorded with a high-speed digital video camera at a framing speed of 600 fps and saved to a PC.

[0175] The flammability range of the refrigerant mixture was measured using a measuring device based on ASTM E681-09 (see Figure 1).

[0176] Specifically, a 12-liter spherical glass flask was used so that the combustion state could be visually observed and recorded on video. The glass flask was designed so that gas could be released from the top lid if excessive pressure was generated due to combustion. Ignition was achieved by discharge from an electrode held at a height of 1 / 3 from the bottom.

[0177] <Test Conditions> Test container: 280mm diameter spherical shape (internal volume: 12 liters) Test temperature: 60℃±3℃ Pressure: 101.3 kPa ± 0.7 kPa Moisture content: 0.0088g ± 0.0005g per gram of dry air (moisture content at 50% relative humidity at 23°C) Refrigerant composition / air mixing ratio: ±0.2 vol.% in 1 vol.% increments Refrigerant composition mixture: ±0.1% by mass Ignition method: AC discharge, voltage 15kV, current 30mA, neon transformer Electrode spacing: 6.4mm (1 / 4inch) Spark: 0.4 seconds ± 0.05 seconds Judgment criteria: • If the flame spreads more than 90 degrees from the point of ignition, it indicates flame propagation (flammability). • If the flame spreads within a 90-degree radius from the ignition point, there is no flame propagation (non-combustible).

[0178] <Refrigeration capacity, condensation glide, evaporation glide, temperature control time> The cooling capacity, condensation glide, evaporation glide, and temperature control time for both cooling and heating operations were determined by performing theoretical calculations of the refrigeration cycle for the mixed refrigerant using Refprop 10.0 (manufactured by the National Institute of Science and Technology (NIST)) under the following conditions. (Air conditioning operation) Evaporation temperature (Te): 5℃ Condensation temperature (Tc): 60℃ Superheating temperature (SH) 5℃ Supercooling temperature (SC) 5℃ Compression work (E Comp.) 0.7kWh Compressor capacity (Comp.): 25cc Compressor rotation speed: 9000 rpm Battery heat capacity: 400kJ / K (Heating operation) Evaporation temperature (Te): -30℃ Condensation temperature (Tc): 70℃ Superheating temperature (SH) 5℃ Supercooling temperature (SC) 5℃ Compression work (E Comp.) 0.7kWh Compressor capacity (Comp.): 25cc Compressor rotation speed: 9000 rpm Battery Heat Capacity 400 kJ / K

[0179] [Table 1]

[0180] [Table 2]

[0181] [Table 3]

[0182] [Table 4]

[0183] [Table 5]

[0184] [Table 6] [Explanation of Symbols]

[0185] 1: Charge Line 2: Sampling Line 3: Thermometer 4: Pressure Gauge 5: Electrode 6: Stirring Blade (made of PTFE)

Claims

1. A battery module comprising a battery and a thermal management unit for performing thermal management of the battery, wherein the thermal management unit comprises a refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)).

2. The battery module according to claim 1, wherein the thermal management method is a direct expansion type or a secondary loop type.

3. The battery module according to claim 1 or 2, wherein the R-1132(E) content is 1 to 70% by mass relative to the refrigerant composition.

4. The battery module according to claim 1 or 2, wherein the R-1132(E) content is 20 to 70% by mass relative to the refrigerant composition.

5. The battery module according to claim 1 or 2, wherein the refrigerant composition further comprises a refrigerant whose boiling point difference with R-1132(E) is 35°C or less.

6. The battery module according to claim 1 or 2, wherein the refrigerant composition further comprises at least one refrigerant selected from the group consisting of 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze), 1,1-difluoroethane (R-152a), difluoromethane (R-32), propane (R-290), and carbon dioxide (R-744).

7. The battery module according to claim 1 or 2, wherein the boiling point of the refrigerant composition is -80 to -35°C.

8. The battery module according to claim 1 or 2, wherein the global warming potential (GWP) of the refrigerant composition is less than 150.

9. The battery module according to claim 1 or 2, wherein the refrigerant composition is weakly flammable, slightly flammable, or non-flammable.

10. The battery module according to claim 1 or 2, wherein the capacity of the battery is 10 kWh or more.

11. The battery module according to claim 1 or 2, wherein the battery is a lithium-ion secondary battery.

12. A battery module according to claim 1 or 2, which is for use in electric vehicles or hybrid vehicles.

13. A refrigerant composition containing trans-1,2-difluoroethylene (R-1132(E)) used for thermal management of batteries.

14. The refrigerant composition according to claim 13, wherein the R-1132(E) content is 20 to 70% by mass relative to the refrigerant composition.

15. Furthermore, the refrigerant composition according to claim 13 or 14 further comprises at least one refrigerant selected from the group consisting of 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze), 1,1-difluoroethane (R-152a), difluoromethane (R-32), propane (R-290), and carbon dioxide (R-744), wherein the battery is a lithium-ion secondary battery.

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