TW202308211A - High-capacity lithium-titanate battery including a metal casing, a positive electrode plate, a negative electrode plate, at least one separation film, and an electrolyte solution - Google Patents

Abstract

The present invention provides a high-capacity lithium-titanate battery, which comprises, at least, a metal casing, in which a receiving space is arranged; a positive electrode plate, which is disposed in the receiving space, the positive electrode plate being formed of a first substrate and at least one positive-electrode active material coating layer; a negative electrode plate, which is disposed in the receiving space, the negative electrode plate being formed of a second substrate and at least one negative-electrode active material coating layer; at least a separation film, which is disposed in the receiving space and located between the positive electrode plate and the negative electrode plate in order to prevent the two from directly contacting each other; and an electrolyte solution, which fills the receiving space, wherein the positive-electrode active material coating layer has a thickness of 37±2 micrometers ([mu]m); the negative-electrode active material coating layer has a thickness of 63±2 [mu]m; and the separation film has a thickness of 9±1 [mu]m.

Description

High capacity lithium titanate battery

The invention relates to a secondary lithium ion battery, in particular to a high-capacity lithium titanate rechargeable battery.

Lithium-titanate battery (Lithium-titanate battery) is a lithium-ion battery, and its positive electrode material is usually lithium-ion-rich lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ) or lithium ternary (NMC) mixed with the above three materials, and lithium ternary mixed with other materials (such as: NCA, LiNi _0.8 Co _0.15 Al _0.05 O ₂ ), etc.; the negative electrode material is lithium titanate (Li ₄ Ti ₅ O ₁₂ ).

Please refer to Figure 1, the conventional lithium titanate battery A is composed of a positive electrode sheet B, two separators C, E, and a negative electrode sheet D, wherein the positive electrode sheet B is coated on both sides of the positive electrode sheet substrate B2 The positive electrode active material coating B1 (such as: lithium cobaltate material) is formed, the negative electrode sheet D is formed by coating the negative electrode active material coating D1 (such as: lithium titanate material) on both sides of the negative electrode sheet substrate D2, the positive electrode sheet B and A separator C is provided in the middle of the negative electrode sheet D for insulation. For cylindrical batteries, the combined positive electrode sheet B and negative electrode sheet D are wound and placed in a circular container. Since the inner edge of the negative electrode sheet D wound in the first circle will ride on the outer edge of the positive electrode sheet B, the negative electrode sheet Another layer of isolation film E is required on the inner edge of D.

Continuing with the above, the general composition structure of the existing lithium titanate battery is taken as an example of a cylindrical battery model 18650 (battery diameter 18.5 mm (mm), length 65 mm), and with the auxiliary description in Figure 1, the aluminum foil of the positive plate B The thickness of the substrate (that is, the positive electrode sheet substrate B2) is 16 ± 1 micron (μm, that is, 10 ^-6 m), the thickness of the positive electrode active material coating B1 is 39 ± 2 μm, and the aluminum foil substrate of the negative electrode sheet D ( That is, the thickness of the negative electrode sheet substrate D2) is also 16 ± 1 μm, the thickness of the negative electrode active material coating D1 is 43 ± 2 μm, and the thickness of the separator C and E is 16 ± 1 μm. In this way, the positive electrode sheet B, the negative electrode sheet The thickness of the assembly of D and two layers of separators C and E is 228 ± 12 μm, and it is filled with electrolyte. The total capacity of a single battery is about 1300 milliamperes (mAh), and the volumetric energy density is 233 Wh/L (Wh/L).

Reducing the thickness of the aluminum foil substrate and the separator can reduce the invalid volume occupied by no active material; increasing the thickness of the positive and negative material coating can increase the effective volume ratio of the active material. Just like the semiconductor manufacturing process, only by breaking through the limitations of the manufacturing process and continuously improving the research and development of production control can the capacity density of the battery be continuously improved.

In the process of coating and rolling the aluminum foil substrate with positive and negative materials, in order to make the pole piece reach a certain level of flatness, the pole piece will be stretched from the feeding roller and the receiving roller. If the thickness of the aluminum foil is too thin, it is easy to cause The lateral shear stress generated by the tension causes the aluminum foil to tear, which is the bottleneck where the current lithium titanate battery positive and negative electrodes cannot use thinner aluminum foil substrates.

In addition, when cutting the pole piece, the cutter needs to cut the aluminum foil substrate and the double-sided active material coating coated on it. Due to the influence of the hardness of the coating, when the shear stress of the upper and lower disc knives is greater than that of the coating particles The bonding force between them will cause cracks in the coating material and the powder will be peeled off. At the same time, the base material of the pole piece will also be damaged by shear force, and sharp thorns will be produced on the cutting edge of the aluminum foil, especially the positive lithium cobalt oxide material. If the degree of brittleness is particularly high, a greater cutting force is required, and the greater the cutting shear stress, the greater the puncture. If the thickness of the separator is too thin, after the positive and negative electrodes and the separator are wound, the aluminum foil burr It will pierce the separator and short circuit with the adjacent negative pole piece. This is the main reason why the current lithium titanate battery cannot reduce the thickness of the separator.

To sum up, the thickness of the positive and negative material coatings is limited by the limits of the electrode sheet coating, rolling, cutting and other processes. The existing technology often uses various means to improve, including: adding adhesives to increase the coating thickness , Add conductive agent to maintain the conductivity of the thickened coating; in addition, adjust the formula of the pole piece to make the pole piece soft, keep the cutting edge sharp, and use negative pressure to vacuum when winding, etc., can remove burrs or suspended particles on the pole piece However, these well-known techniques have been exhausted to the extreme. How to find the optimal ratio of coating thickness of the positive and negative electrodes so that the reaction between the positive and negative active materials can achieve the most sufficient reaction becomes the key to increasing the capacity density of the battery. Lithium titanate battery manufacturers often use trial and error to adjust the relative thickness of the positive electrode coating and the negative electrode coating, which often wastes excess materials and fails to achieve the best overall capacity density.

Compared with lithium-ion batteries such as lithium cobaltate, lithium ternary, and lithium iron phosphate, lithium titanate batteries have the advantages of high safety, fast charging, long service life, and suitable for use in low temperature environments. However, the nominal voltage of the battery It is 2.4 volts (V), resulting in the disadvantage of low battery capacity density. Therefore, how to improve the capacity density of lithium titanate batteries has become the competition of lithium titanate battery technology.

The factors that affect the overall capacity density of a battery are mainly divided into two parts: material chemical properties and physical volume. In order to increase the capacity density of the battery, most of the early lithium titanate batteries started from improving the material itself and additives in the laboratory, and gradually increased the gravimetric capacity density of the lithium titanate material to 160 milliampere hours/gram (mAh/g), which is very It is close to the theoretical value of 175mAh/g. In terms of the chemical properties of lithium titanate materials, there is very limited room for subsequent improvement.

Compared with other lithium-ion battery manufacturers, there are very few manufacturers with lithium titanate battery manufacturing practice. In addition to the theory of material characteristics, the knowledge of various characteristic data and control parameters of production is limited. Possible methods, lack of complete system research. The battery cell is composed of a positive electrode, a negative electrode, a separator, an electrolyte, a container, etc. The main volume is: the aluminum foil substrate (collector) of the positive electrode sheet (collector) and the active material coating (active material) of the positive electrode sheet, and the aluminum foil of the negative electrode sheet Substrate and negative electrode active material coating, and separator, so the capacity density of the battery is in addition to the capacity density corresponding to the chemical characteristics of the positive and negative electrode materials themselves, how to improve the coating, rolling, cutting, and rolling of battery manufacturing The winding process and making good use of the limited physical volume space become the key to determine the battery capacity density.

In view of the fact that lithium titanate battery has become a common type of battery for energy storage equipment and electric vehicle products, the inventor finally designed a high-efficiency The capacity lithium titanate battery is expected to be able to effectively provide better products and give better use experience through the advent of the present invention.

One object of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell with an accommodating space inside; material and at least one positive electrode active material coating; a negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; at least one separator is located in the In the accommodating space, and located between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not directly contact each other; and an electrolyte is filled in the The solution in the accommodation space, the electrolyte can transfer metal ion substances in the accommodation space; wherein, the thickness of the positive electrode active material coating is 37 ± 2 microns, and the thickness of the negative electrode active material coating is 63 ± 2 microns, The thickness of the isolation film is 9 ± 1 micron.

Optionally, the first substrate and the second substrate are made of aluminum foil.

Optionally, the thickness of the first substrate and the second substrate is 10±1 micron.

Optionally, the thickness of the pole piece of the high-capacity lithium titanate battery is 238 ± 12 microns.

Optionally, the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is above 310 Wh/L.

Optionally, the positive electrode sheet and the negative electrode sheet are respectively applied by a rolling machine with a tension of 6.7 ± 0.3 million Pascals, and the inclination of the horizontal tension angle is formed within ± 1.5 degrees.

Optionally, the first substrate and the second substrate are made of copper foil.

Optionally, the thickness of the first base material and the second base material is 6±1 micron.

Optionally, the pole piece composition thickness of the high-capacity lithium titanate battery is 230 ± 12 microns.

Optionally, the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is above 320 Wh/L.

Another object of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell, which is provided with an accommodating space; material and at least one positive electrode active material coating; a negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; at least one separator is located in the In the accommodating space, and located between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not directly contact each other; and an electrolyte is filled in the The solution in the accommodation space, the electrolyte can transfer metal ion substances in the accommodation space; wherein, the product of the compact density, coating thickness, capacity density and active material ratio of the positive electrode active material coating is equivalent to It is the product of the compacted density, coating thickness, capacity density and active material ratio of the negative electrode active material coating.

Optionally, the ratio of the coating thickness of the positive electrode active material coating to the coating thickness of the negative electrode active material coating is 5.7:10 to 6.1:10.

Yet another object of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell with an accommodating space inside; The substrate is composed of at least one positive electrode active material coating; a negative electrode sheet is located in the containing space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; at least one separator is located in the In the accommodating space, and located between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two do not directly contact each other; and an electrolyte is filled in The solution in the accommodation space, the electrolyte can transfer metal ion substances in the accommodation space; wherein, the thickness of the positive active material coating is 37 ± 2 microns, and the thickness of the negative active material coating is 63 ± 2 microns , the thickness of the separator is 9 ± 1 micron, and the product of the compacted density, coating thickness, capacity density and active material ratio of the positive active material coating is equivalent to the compaction of the negative active material coating The product of solid density, coating thickness, capacity density and active material ratio.

In order to facilitate your review committee to further understand and understand the purpose, technical features and effects of the present invention, the embodiments are hereby combined with the drawings, and the details are as follows:

In order to make the purpose, technical content and advantages of the present invention more clear, the following will further describe the disclosed embodiments of the present invention in detail with reference to the specific embodiments and with reference to the accompanying drawings. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification, and the present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications , various modifications and changes can be made without departing from the concept of the present invention. In addition, it is stated in advance that the drawings of the present invention are only simple schematic illustrations, and are not drawn according to actual dimensions.

It should be understood that the examples used anywhere in the description of the present invention, including the use of any term, are only illustrative and in no way limit the scope and meaning of the present invention or any term. Likewise, the present invention is not limited to various embodiments disclosed in the specification. Although the terms first, second or third, etc. may be used herein to describe various elements, each element should not be limited by the aforementioned terms, which are mainly used to distinguish one element from another element and should not be used for any purpose. The elements impose no substantive limitations and should not limit the order in which the various elements can be assembled or arranged in a practical application.

The present invention is a high-capacity lithium titanate battery. Please refer to Figures 2 to 6. In the first embodiment, the lithium titanate battery 1 at least includes a metal shell 2, which is provided with an accommodating space 20 A positive electrode sheet 3 is located in the accommodation space 20, the positive electrode sheet 3 is composed of a first substrate 32 and at least one positive electrode active material coating 31; a negative electrode sheet 4 is located in the accommodation space 20, the negative electrode The sheet 4 is composed of a second substrate 42 and at least one negative electrode active material coating 41; at least one separator 5 is located in the accommodation space 20, and between the positive electrode sheet 3 and the negative electrode sheet 4, the isolation Membrane 5 can separate the positive electrode sheet 3 and the negative electrode sheet 4, so that the two can not directly contact each other; Metal ion substances are transferred in the space 20; wherein, the thickness of the positive electrode active material coating 31 is 37 ± 2 μm, the thickness of the negative electrode active material coating 41 is 63 ± 2 μm, and the thickness of the separator 5 is 9 ± 1 μm. μm.

Continuing from the above, please refer to Figures 2 to 3 again. In the first embodiment, the positive electrode material of the present invention is represented by lithium cobalt oxide, and its chemical reaction formula is: Positive electrode: LiCoO ₂ ⇌Li _1-x CoO ₂ + _x Li ⁺ + _x e ^- ; Negative electrode: Li ₄ Ti ₅ O ₁₂ + _x Li ⁺ + _x e ^- ⇌Li ₄ + _x Ti ₅ O ₁₂ .

As mentioned above, the material of the first substrate 32 and the second substrate 42 is aluminum foil, and the thickness of the first substrate 32 and the second substrate 42 is 10 ± 1 μm, so that the high-capacity lithium titanate battery The pole piece composition thickness of the pool is 238 ± 12 μm, wherein, the pole piece composition thickness consists of a first substrate 32, two layers of positive electrode active material coatings 31, a second substrate 42, two layers of negative electrode active material coatings 41 and two separators 5, and the effective volumetric energy density of the positive electrode sheet 3 and the negative electrode sheet 4 is above 310 Wh/L.

Referring back to Figures 2 and 3, in the second embodiment, the first base material 32 and the second base material 42 are made of copper foil, and the first base material 32 and the second base material The thickness of 42 is 6 ± 1 μm, and the thickness of the pole piece composition of the high-capacity lithium titanate battery is 230 ± 12 μm, wherein, the thickness of the pole piece composition is composed of a first substrate 32, two layers of positive electrode active material coating 31. A piece of second substrate 42, two layers of negative electrode active material coating 41 and two separator films 5 are summed up, and the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is 320 watt-hours/liter (WH/ L) above.

Please refer to Figures 3 to 6, the first base material 32 and the second base material 42 in this embodiment are in the coating and rolling process of positive and negative electrode materials. The tensile force of the aluminum foil will make the aluminum foil stretch, but it is not the cause of the tearing of the aluminum foil, but when the surface of the aluminum foil is not parallel to the tensile force, the lateral shear stress generated by the tensile force exceeds the shear stress that the aluminum foil can withstand. According to the mechanical calculation and the comparison of the shear stress of the material, it is concluded that the angle between the plane of the aluminum foil and the tensile force of 6.7 ± 0.3 million Pascals (MPa) applied by the machine must be controlled within ± 1.5 degrees, and the thinnest can be 10 ± 1 μm Aluminum foil, still maintains the foil from cracking.

Please refer to Figures 4 to 6, the battery pole pieces coated with active materials are sent to the roller press 8 from the end of the unwinding shaft 7, and are recovered into rolls at the end of the rewinding shaft 9 after being compacted by the rollers. When the unwinding shaft 7 before rolling or the receiving shaft 9 after rolling is tilted, the tensile normal stress F _X will generate a lateral vertical component force F _Y , when the component shear stress S _{S is} too large , will cause tearing and damage to the pole piece substrate. In order to make the pole piece have a certain flatness during rolling, after many practical research experiments by the inventor, the calculation method is as follows: vertical component force (F _Y ) = total tensile tension (F) × sin a; shear stress (S _S ) = F _Y / (total width of the pole piece (w) × thickness of the assembly (t)); tension (S _N ) = F / (w × t).

On the bearing, the feed roller must have a tensile tension (S _N ) of at least 6 ± 0.3 MPa, and the aluminum foil shear stress ( _SS ) strength is 0.18 ± 0.01 MPa, so the horizontal inclination angle of the feed roller must not exceed sin ^-1 (0.18/6) = 1.72 degrees. When applied to an aluminum foil substrate with a thickness of 10 μm and a total width (w) of the pole piece of 450 mm, the total tensile force (F) applied by the roller is calculated as follows: F= S _N × w × t = 6 MPa × 0.45 m × 10 μm = 27 ± 1.5 Newtons (N).

Bearing in mind, in order to optimize the various qualities of pole piece rolling and the control of the roller level, the tension of the discharge shaft 7 is increased to 30 ± 1.5 N, that is, the total tension (F) is increased to 6.7 ± 0.3 MPa, In order to ensure that the shear stress (S _S ) is less than 0.18 ± 0.01 MPa, that is, the horizontal inclination angle of the discharge shaft 7 must be controlled within ± 1.5 degrees (∘), the calculation method is as follows: S _N = F / (w × t) = 30 N / (0.45m × 10 μm) = 6.7 MPa; a = sin ^-1 (0.18 / 6.7) = 1.54∘.

In addition, replacing aluminum foil with copper foil with higher shear stress ( _SS ) can further reduce the thickness of the pole piece base material, and also apply a tensile force of 30 ± 1.5 N to the discharge shaft 7, that is, the total width of the pole piece ( w) The 450 mm copper foil base material bears a total tensile tension (F) of 6.7 ± 0.3 MPa, and controls the horizontal inclination angle of the feed roller within ± 1.5 degrees to ensure that the shear stress is less than 0.18 ± 0.01 MPa, the thinnest available 6 ± 1 μm copper foil is used as the pole piece substrate.

The positive electrode active material coating 31 and the negative electrode active material coating 41 are bordered by the separator 5. For each corresponding unit area, under the limitation of the limit thickness of the coating, it is necessary to prepare the two materials. content ratio, so that the positive and negative active materials can achieve the most sufficient chemical reaction, please refer to the 2 to 3 shown in Figure 3, in the third embodiment, the inventors have studied the positive active material coating 31 and the negative active material The optimal thickness ratio of the coating 41, and after careful analysis of various factors affecting the capacity through the experimental results, it is known that: the compacted density A _P of the positive electrode active material coating 31 (grams/cubic centimeter (g/cm ³ )) , positive electrode coating thickness d _P (centimeter (cm)), capacity density E _P (milliampere hours/gram (mAh/g)) and active material ratio R _P (percentage (%)) of the four products, which is equivalent to The negative electrode active material coating has a compacted density A _N (gram/cubic centimeter (g/cm ³ )), a negative electrode coating thickness d _N (centimeter (cm)), a capacity density E _N (milliampere hour/gram (mAh /g)) and the active substance ratio R _N (percentage (%)) of the four products, namely: A _P × d _P × E _P × R _P = A _N × d _N × E _N × R _N .

As above, in this embodiment, the A _P value is 3.66 g/cm ³ , the E _P value is 145mAh/g, the R _P value is 96%, the A _N value is 2.0 g/cm ³ , and the E _N value is 160mAh/g g. The value of R _N is 94%. Therefore, calculated from the above calculation, d _P / d _N = 300.8 / 509.5 = 59%, but it is not limited to this. In actual production, tolerance problems may also occur, so that the positive electrode The ratio of the coating thickness d _P to the negative electrode coating thickness d _N can be 59 ± 2% (ie, 5.7:10 to 6.1:10). Next, under the condition that the capacitance of the positive and negative electrodes is equal, the thickness d _N of the negative electrode coating will be greater than the thickness d _P of the positive electrode coating. Therefore, in the manufacturing process of lithium titanate battery 1, the thickness d _N of the negative electrode coating will meet Regarding the problem of adhesion and cutting powder, it can be said that the capacitance of the lithium titanate battery 1 is determined by the thickness d _N of the negative electrode coating. Restricted by the negative electrode coating production process, the negative electrode coating thickness _dN of the negative electrode coating 41 with lithium titanate as the negative electrode active material coating 41 with stable quality can be achieved at present, and then according to the above-mentioned positive electrode coating thickness _dP and The ratio of the negative electrode coating thickness d _N is calculated from 5.7:10 to 6.1:10, and the positive electrode coating thickness d _P is 37 ± 2 μm. In this way, the thinnest electrode substrate and the best The thickness of the positive electrode coating d _P and the negative electrode coating thickness d _N , with regard to the existing pole piece roll cutting process, a separator 5 with a thickness of 9 ± 1 μm can be used to control the burrs from piercing the separator 5 so that the positive electrode piece 3 Short circuit with negative electrode sheet 4.

Furthermore, the total capacity Q of the battery pole piece is known by the product of the capacitance per unit area and the total area of the pole piece, that is, the compacted density, coating thickness, capacity density, active material ratio, pole piece width H (such as As shown in Figure 2, that is, the product of the internal height of the shell 2) and the lateral length L of the pole piece, it is known that taking the known cylindrical battery 18650 as an example, the inner space of the metal can can accommodate the pole piece to be wound into a diameter of 17.6 mm and a height of 55mm (ie, 5.5 cm), the volume of the cylinder is 13380 mm ³ . However, about 3% of the invalid accommodation space in the center (such as the space occupied by the reel) must be deducted when the pole piece is wound. Therefore, the effective accommodation space inside the metal can is 12979 mm ³ ; the stretched volume of the pole piece and insulating sheet before winding is {(positive electrode coating thickness × 2 + positive electrode plate substrate thickness) + (negative electrode coating thickness × 2 + Negative pole piece base material thickness) + (separator film thickness × 2)} × H × L, and due to the material deformation in the thickness direction when the pole piece is wound, it cannot be completely tightly fitted, and there is still a gap between each layer of pole piece A 10% allowable deformation volume is required. Using the existing technology, the thickness (t) of the assembly of positive and negative electrodes plus two layers of separator is 228 μm. Considering the possible tolerance problems during production, it can be wound in the accommodation space 20 The horizontal length L of the pole piece is derived from the following calculation formula based on the average value of each thickness, {(39 × 2 + 16) + (43 × 2 + 16) + (16 × 2)} × 1.1 / 1000 × 55 × L =12979 mm ³ ; The transverse length L of the pole piece is 941 mm.

Continuing from the above, the capacity of the pole piece is calculated as the capacitance per unit area multiplied by the total area, that is, the total positive electrode capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0039 × 2 × 145 × 0.96) × 5.5 × 94.1 = 2057 mAh; The total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H × L = (2.0 × 0.0043 × 2 × 160 × 0.94) × 5.5 × 94.1 = 1339mAh.

Continuing from the above, since the effective capacity of the battery is determined by the capacitance of one of the positive electrode or the negative electrode with a smaller amount of material, the positive electrode material used in the prior art is 718mAh more than the negative electrode material, that is, 35% of the positive electrode material , not only does not contribute to the capacity of the battery, but also occupies more invalid space, so that the effective volume energy density of the battery pole piece is: 1339mAh × 2.4V / 13380 mm ³ = 240 ± 12 WH/L.

However, the present invention adopts an optimized design, wherein, when the first substrate 32 and the second substrate 42 are made of aluminum foil, a substrate with a thickness of 10 ± 1 μm is used, and the thickness of the positive electrode active material coating 31 is 37 μm. ± 2 μm, the thickness of the negative electrode active material coating 41 is 63 ± 2 μm, the thickness of the separator 5 is 9 ± 1 μm, and the thickness of the pole piece is 238 ± 12 μm. Considering the tolerance problem that may be derived during production, the tolerance The horizontal length L of the aluminum foil pole piece that can be wound in the space of the tank is derived from the following calculation formula based on the average value of each thickness: {(37 × 2 + 10) + (63 × 2 + 10) + (9 × 2)} × 1.1 / 1000 × 55 × pole piece transverse length L = 12979 mm ³ ; pole piece transverse length L is 901 mm.

Based on the above, the total positive electrode capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0037 × 2 × 145 × 0.96) × 5.5 × 90.1 = 1868mAh;

The total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H ×L = (2.0 × 0.0063 × 2 × 160 × 0.94) × 5.5 × 90.1 = 1878mAh;

The effective volumetric energy density of the battery pole piece is 1868mAh × 2.4V / 13380 mm ³ = 335 WH/L, but it is not limited to this. Considering the tolerance of the tank and the validity of the internal space during production, the effective capacity of the battery pole piece The volumetric energy density can also be 335 ± 5% WH/L.

Based on the above, the capacity ratio of the present invention relative to the prior art is 1868 / 1339 = 1.395, and the capacity is increased by 39.5%. The experimental results prove that the capacity of the battery of the present invention applied to the 18650 model can reach more than 1750mAh. Compared with the capacity of the prior art of 1300mAh, the battery Capacity increased by 34.6%.

Furthermore, the present invention uses a thinner 6 ± 1 μm copper foil substrate to replace 10 ± 1 μm aluminum foil, and the thickness (t) of the assembly of the positive and negative electrodes plus two layers of separator is 230 ± 12 μm, considering the possibility of Derived from the tolerance problem, the horizontal length L of the copper foil pole piece that can be wound in the space of the container is derived from the following calculation formula based on the average value of each thickness: {(37 × 2 + 6) + (63 × 2 + 6) + (9 × 2)} × 1.1 / 1000 × 55 × L = 12979 mm ³ ; the transverse length L of the copper foil pole piece is 933mm.

Based on the above, the total positive electrode capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0037 × 2 × 145 × 0.96) × 5.5 × 93.3 = 1935mAh;

The total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H × L = (2.0 × 0.0063 × 2 × 160 × 0.94) × 5.5 × 93.3 = 1945mAh;

The effective volumetric energy density of the battery pole piece is 1935mAh × 2.4V / 13380 mm ³ = 347 WH/L, but it is not limited to this. Considering the tolerance of the tank and the validity of the internal space during production, the effective capacity of the battery pole piece The volumetric energy density can also be 347 ± 5% WH/L.

Based on the above, the capacity ratio of the 6 μm copper foil substrate used in the present invention compared to the prior art is 1935 / 1339 = 1.445, and the capacitance can be increased by up to 44.5%.

In addition to being cylindrical, the outer shape of the housing 2 of the present invention can also be rectangular. Please refer to FIG. Flatten and put it into the casing 2 to form a rectangular (prismatic) battery; and the material of the casing 2 can be aluminum foil, please refer to the positive electrode sheet 3 and the negative electrode sheet 4 after rolling as shown in Figure 8, After being separated by the separator 5, it is cut and stacked into the casing 2, so that the positive electrode sheet 3, the negative electrode sheet 4 and the separator 5 are stacked in a sheet shape, and the top surface 21 of the casing 2 and the bottom surface of the casing 22 will cover the positive electrode sheet 3, negative electrode sheet 4 and separator 5 to form a pouch battery, so that the space in the casing 2 can be fully utilized and the invalid space in the casing 2 can be reduced . Furthermore, the number of the positive electrode sheet 3, the negative electrode sheet 4 and the isolation film 5 is not limited to the number drawn in Figure 8, and the industry can match the corresponding number of positive electrode sheet 3, negative electrode sheet 4 and isolation film according to its product requirements. Film 5.

According to, the above description is only a preferred embodiment of the present invention, but the scope of rights claimed by the present invention is not limited thereto. According to those who are familiar with the art, according to the technical content disclosed in the present invention, they can The easily conceivable equivalent changes shall all fall within the scope of protection of the present invention.

[Conventional knowledge] A: Lithium titanate battery B: Positive electrode sheet B1: Positive electrode active material coating B2: Positive electrode sheet substrate C, E: separator D: Negative electrode sheet D1: Negative electrode active material coating D2: Negative electrode sheet substrate [Invention] 1: Lithium titanate battery 2: Housing 20: Accommodating space 21: Housing top surface 22: Housing bottom surface 3: Positive electrode sheet 31: Positive electrode active material coating 32: First base material 4: Negative electrode sheet 41: Negative electrode active material coating 42: Second substrate 5: Separator film 6: Electrolyte 7: Unwinding shaft 8: Roller press 9: Receiving shaft a: Angle d _N : Negative electrode coating thickness d _P : Positive electrode Coating thickness F: total tension F _X : normal stress F _Y : vertical component force H: pole piece width t: assembly thickness w: total pole piece width

[Fig. 1] is a cross-sectional view of the pole piece composition of a conventional lithium titanate battery; [Fig. 2] is a schematic diagram of the internal structure of the lithium titanate battery of the present invention; [Fig. 3] is a sectional view of the pole piece composition of the lithium titanate battery of the present invention; [Fig. 4] is a schematic diagram of the roll-pressing of the pole piece of the lithium titanate battery of the present invention; [Fig. 5] is a schematic diagram of tensile force and shear stress analysis of the pole piece roll pressure of the lithium titanate battery of the present invention; [Fig. 6] is a schematic diagram of the pressure analysis of the pole piece roll of the lithium titanate battery of the present invention; [Fig. 7] is a schematic diagram of the internal structure of the rectangular battery of the lithium titanate battery of the present invention; and [Fig. 8] is a schematic diagram of the internal structure of the pouch battery of the lithium titanate battery of the present invention.

1: Lithium titanate battery

3: Positive plate

31: Positive electrode active material coating

32: First substrate

4: Negative plate

41: Negative electrode active material coating

42: Second substrate

5: Isolation film

d _N : negative electrode coating thickness

d _P : positive coating thickness

t: Assembly thickness

Claims (14)

A high-capacity lithium titanate battery comprising at least: A metal shell, which is provided with an accommodating space; A positive electrode sheet is located in the accommodating space, and the positive electrode sheet is composed of a first substrate and at least one positive electrode active material coating; A negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; At least one separator is located in the containing space and between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not directly contact each other; and An electrolyte, which is a solution filled in the holding space, and the electrolyte can transfer metal ion substances in the holding space; Wherein, the thickness of the positive electrode active material coating is 37 ± 2 microns, the thickness of the negative electrode active material coating is 63 ± 2 microns, and the thickness of the separator is 9 ± 1 microns. The high-capacity lithium titanate battery according to claim 1, wherein the first substrate and the second substrate are made of aluminum foil. The high-capacity lithium titanate battery according to claim 2, wherein the thickness of the first substrate and the second substrate is 10 ± 1 micron. The high-capacity lithium titanate battery as described in claim 3, wherein the thickness of the pole pieces of the high-capacity lithium titanate battery is 238 ± 12 microns. The high-capacity lithium titanate battery according to claim 4, wherein the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is above 310 Wh/L. The high-capacity lithium titanate battery as described in claim 5, wherein, the positive electrode sheet and the negative electrode sheet are respectively applied to the positive electrode sheet through a rolling machine, and the tensile force is 6.7 ± 0.3 million Pascals, and the tension horizontal angle The inclination is formed within ± 1.5 degrees. The high-capacity lithium titanate battery as claimed in claim 1, wherein the material of the first base material and the second base material is copper foil. The high-capacity lithium titanate battery as claimed in item 7, wherein the thickness of the first substrate and the second substrate is 6 ± 1 micron. The high-capacity lithium titanate battery as described in claim 8, wherein the thickness of the pole pieces of the high-capacity lithium titanate battery is 230 ± 12 microns. The high-capacity lithium titanate battery according to claim 9, wherein the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is above 320 Wh/L. The high-capacity lithium titanate battery as described in claim 10, wherein, the positive electrode sheet and the negative electrode sheet are applied to the positive electrode sheet and the negative electrode sheet through a rolling machine, respectively, with a tension of 6.7 ± 0.3 million Pascals, and the tension level The inclination of the angle is formed within ± 1.5 degrees. A high-capacity lithium titanate battery comprising at least: A metal shell, which is provided with an accommodating space; A positive electrode sheet is located in the accommodating space, and the positive electrode sheet is composed of a first substrate and at least one positive electrode active material coating; A negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; At least one separator is located in the containing space and between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two do not directly contact each other; and An electrolyte, which is a solution filled in the holding space, and the electrolyte can transfer metal ion substances in the holding space; Wherein, the product of compaction density, coating thickness, capacity density and active material ratio of the positive electrode active material coating is equivalent to the compaction density, coating thickness, capacity density and active material ratio of the negative active material coating. The product of the four ratios of matter. The high-capacity lithium titanate battery as claimed in claim 12, wherein the ratio of the coating thickness of the positive electrode active material coating to the coating thickness of the negative electrode active material coating is 5.7:10 to 6.1:10. A high-capacity lithium titanate battery comprising at least: A metal shell, which is provided with an accommodating space; A positive electrode sheet is located in the accommodating space, and the positive electrode sheet is composed of a first substrate and at least one positive electrode active material coating; A negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; At least one separator is located in the containing space and between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two do not directly contact each other; and An electrolyte, which is a solution filled in the holding space, and the electrolyte can transfer metal ion substances in the holding space; Wherein, the thickness of the positive electrode active material coating is 37 ± 2 microns, the thickness of the negative electrode active material coating is 63 ± 2 microns, the thickness of the separator is 9 ± 1 microns, and the pressure of the positive electrode active material coating is The product of solid density, coating thickness, capacity density and active material ratio is equivalent to the product of compact density, coating thickness, capacity density and active material ratio of the negative electrode active material coating.

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