TWI600203B - Composite lithium secondary battery - Google Patents

Description

Composite lithium secondary battery (1)

The present invention relates to a lithium secondary battery, and more particularly to a composite lithium secondary battery having a plurality of regions on the surface of the positive electrode to coat different positive active materials.

In recent years, portable electronic devices such as cameras, digital still cameras, mobile phones, and notebook computers have been widely used. In order to facilitate carrying and increasing the use time, how to reduce the size, weight and extend the service life of the aforementioned electronic devices has become a necessity. The main technical issues. Therefore, in the field of batteries, lightweight secondary batteries capable of providing high energy density have been developed as power sources for these portable electronic devices to meet the aforementioned usage requirements.

A lithium secondary battery is a secondary battery that achieves charging and discharging reactions by intercalation and deintercalation of lithium ions, and is widely used because it can provide higher energy density than lead batteries and nickel-cadmium batteries. As shown in FIG. 1A and FIG. 1B, the current lithium secondary battery A is assembled by providing a separator between the positive electrode sheet and the negative electrode sheet, and then wound into a core A1 and then placed in a common cylindrical shape (FIG. 1A). Or square (Fig. 1B) in the battery case A2. The lithium secondary battery includes an electrolyte, a positive electrode, and a negative electrode. The positive electrode is formed by coating a positive electrode active material layer including a positive electrode active material on a positive electrode current collecting plate/sheet, and the negative electrode is coated on a negative electrode current collecting plate/sheet. An anode active material layer including a negative electrode active material is disposed, and the electrolyte includes a solvent in which an electrolyte salt is dissolved. Among them, the positive electrode material and the negative electrode material have the greatest influence on improving the capacitance density and the reduction of the lithium secondary battery, and are also the most critical.

In the negative electrode material portion, since the crystal structure changes very little when the carbon material is intercalated and deintercalated with lithium ions, the current negative electrode material widely uses a carbon material such as graphite to make the lithium secondary battery stable in characteristics such as battery capacity. which performed. In the positive electrode material part, the positive electrode materials commonly used in lithium batteries are lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ , LiMnO ₂ ), lithium cobalt nickel manganese oxide. Lithium oxides such as (ternary materials, LiNiCoMnO ₂ , LNCM), nickel cobalt cobalt aluminate (ternary materials, LiNi _x Co _y Al _1-xy O ₂ , LNCA), and lithium iron phosphate (LiFePO ₄ , LFP).

It is worth noting that the current positive electrode is prepared by coating a single type of positive electrode material on both sides of all positive current collecting plates/sheets in the battery. However, various positive electrode materials have advantages and disadvantages in performance performance, for example, Lithium manganese oxide (LiMn ₂ O ₄ ) has a low thermal capacity, but it is suitable for medium and large lithium batteries or high power batteries that emphasize high power performance and safety considerations. Iron (LiFePO ₄ ) has higher thermal stability than lithium manganese oxide (LiMn ₂ O ₄ ) and does not have safety problems such as explosion or overheating. It is suitable for applications with high power and low capacity requirements. A power battery or a large battery; when a single type of positive electrode material is used, the lithium secondary battery can only produce better performance in some characteristics, and is insufficient.

In view of the above-described problem that the lithium secondary battery has limited performance performance due to the application of a single type of positive electrode material to the positive electrode, the present invention aims to pass lithium iron phosphate (LiFePO ₄ , LFP) and a lithium-containing ternary system. The different positive electrode materials of the oxide are coated on different regions of the same positive electrode surface to obtain the advantages of different positive electrode materials during charging and discharging of the lithium secondary battery, thereby providing a high voltage, high capacitance and safety. High composite lithium secondary battery.

In order to achieve the above object, a composite lithium secondary battery according to the present invention comprises at least one positive electrode layer, at least one negative electrode layer, and a plurality of separators interposed between the positive electrode layer and the negative electrode layer. The positive electrode layer, the negative electrode layer and the separator are laminated and wound to form the composite lithium secondary battery; the positive electrode layer includes a positive electrode material capable of intercalating and deintercalating the electrode reactant, and the positive electrode layer has one side end At least one positive electrode tab, and the positive electrode material is coated on both sides of the positive electrode layer, and the positive electrode layer is defined as an inner end at one end of the center after winding, and an outer end at one end of the outer layer; And comprising a negative electrode material capable of inserting and extracting the electrode reactant, the negative electrode layer has at least one negative electrode tab at one end thereof, and the negative electrode material is coated on both sides thereof; wherein the two sides of the positive electrode layer, Correspondingly, a plurality of regions and at least one blank region are disposed, each of which is coated with a positive electrode material, and the positive electrode materials on both sides of the positive electrode layer are correspondingly coated, each region and above The positive electrode material is separated by the blank region, and the gap width D of the blank region is 0.5 mm or more (D≧0.5 mm); at least one region coated with the positive electrode material on the same side surface of the positive electrode layer The positive electrode material coated in other regions is different, and the positive electrode material is selected from the group consisting of lithium iron phosphate (LiFePO ₄ , LFP) and a lithium-containing ternary oxide.

Further, in the composite lithium secondary battery of the present invention, the positive electrode material is a combination of olivine-structured lithium iron phosphate (LFP) and lithium nickel cobalt aluminate (LNCA) or lithium cobalt nickel manganate (LNCM). Among them, the working voltage range of LFP+LNCA composite lithium secondary battery can reach 4.5V~2.7V, and the capacitance can reach 175mAh/g or more; the working voltage range of LFP+LNCM composite lithium secondary battery can reach 4.4V~ 2.6V, the capacitance can reach 185mAh / g or more.

Further, in the composite lithium secondary battery of the present invention, the gap width D of the blank region is less than or equal to 5 cm and greater than or equal to 0.5 mm (5 cm ≧ D ≧ 0.5 mm) to avoid overlapping and thickening of the coating on each region. It also shows the discharge performance of the core.

Further, in the composite lithium secondary battery of the present invention, the negative electrode material is selected from a graphite-based or coke-based carbon material.

Further, in the composite lithium secondary battery of the present invention, the positive electrode material to which the region of the positive electrode layer closest to the outer end is applied is lithium iron phosphate (LFP).

Further, in the composite lithium secondary battery of the present invention, the blank area connecting the both ends of the positive electrode layer is defined as a longitudinal blank area, and the blank area connecting the inner end and the outer end of the positive electrode layer is a horizontal blank area, obliquely a blank area connecting the two side ends or the inner side and the outer side of the positive electrode layer is an oblique blank area, such that the longitudinal blank area, the horizontal blank area and/or the oblique direction are correspondingly provided on the side surface of the positive electrode layer The blank area is separated by the plurality of areas.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings.

An embodiment of the composite lithium secondary battery of the present invention will be described with reference to FIG. 3 as shown in FIG. 3A to FIG. 6C.

The core of the composite lithium secondary battery of the present invention comprises at least one positive electrode layer 10, at least one negative electrode layer 20, and a plurality of separators 30 interposed between the positive electrode layer 10 and the negative electrode layer 20, The positive electrode layer 10, the negative electrode layer 20, and the separator 30 are laminated and wound to form a core, and the core is placed in a battery case to form the composite lithium secondary battery of the present invention. In this embodiment, as shown in FIG. 2, the core may be composed of a positive electrode layer 10, an inner isolation film 30, a negative electrode layer 20, and an outer isolation film 30 to form an electrode group, or may increase the capacitance requirement. The aforementioned electrode group.

As shown in FIG. 2, the positive electrode layer 10 has opposite side faces 11, 12, and the opposite side ends 13 and 14 along the long side and the opposite ends along the short side are defined between the two side faces 11, 12. Along the end of the short side, after the positive electrode 10 is wound, one end of the center is an inner end 15 and one end of the outer side is an outer end 16; and a side end 13 along the long side has at least one positive electrode tab. 17. The two sides 11, 12 are provided with a coating zone for coating a positive electrode material capable of intercalating and deintercalating an electrode reactant such as lithium ions, and the coating zone is provided with a plurality of regions 18 and at least one blank. a region 19, each of which is coated with a positive electrode material, and a positive electrode material on both side faces 11 and 12 of the positive electrode layer 10 is correspondingly applied to the device, and between the region 18 and the positive electrode material thereon The blank regions 19 are spaced apart; the positive electrode material coated with at least one region 18 on the same side 11/12 of the positive electrode layer 10 is different from the positive electrode material coated by the other regions 18.

In this embodiment, the blank region 19 on the positive electrode layer 10 is mainly formed as an elongated region between the regions 18 for avoiding overlap of the positive electrode material coating and increasing the thickness of the overlap, thereby further inter-electrode spacing. It is difficult to laminate the laminates, resulting in problems affecting the discharge performance of the battery. The gap width D of the blank region 19 is 0.5 mm or more (D ≧ 0.5 mm), and the interval width D can be adjusted to be less than or equal to 5 cm and greater than or equal to 0.5 mm depending on the shape and size of the applied lithium secondary battery. 5cm≧D≧0.5mm) to meet the actual battery design and use requirements.

The positive electrode material of the composite lithium secondary battery of the present invention is selected from the group consisting of lithium iron phosphate (LiM _x PO ₄ , hereinafter abbreviated as LFP) and a lithium-containing ternary oxide. The lithium-containing ternary oxide is preferably selected from lithium nickel cobalt aluminate (LiNi _x Co _y Al _1-xy O ₂ , hereinafter referred to as LNCA) or lithium cobalt nickel manganese oxide (LiNiCoMnO ₂ , hereinafter referred to as LNCM) to form A combination of lithium iron phosphate and nickel cobalt cobalt aluminate (LFP+LNCA) or lithium iron phosphate with lithium cobalt nickel manganese oxide (LFP+LNCM).

Further, the positive electrode layer 10 of the present invention is composed of a positive electrode material coated on a surface of a piece of aluminum substrate (for example, an aluminum foil), and the positive electrode material may further include a conductive agent and a binder for using the lithium as described above. The active material of the oxide composition is coated on the surface of the aluminum substrate. The adhesive may be a resin adhesive, but is not limited thereto.

The negative electrode layer 20 has two opposite side faces 21, 22 having opposite sides 23, 24 along the long sides and opposite ends along the short sides, defining the ends of the short sides. After the negative electrode layer 20 is wound, one end of the center is an inner end 25, and one end of the outer side is an outer end 26; and a side end 23 along the long side has at least one negative electrode tab 27, the two sides 21, 22 is provided with a coating zone for coating a negative electrode material capable of intercalating and deintercalating electrode reactants such as lithium ions.

The negative electrode material of the composite lithium secondary battery of the present invention may be selected from a graphite or coke-based carbon material; further, the negative electrode layer 20 of the present invention is coated on the surface of a piece of copper substrate (for example, copper foil) by a negative electrode material. The anode material may further include a conductive agent and a binder for coating the carbon material on the surface of the aluminum substrate; the binder may be a resin binder, but is not limited thereto. In addition, the separator 30 of the present invention is a microporous and porous film, and the material may be selected from PP or PE materials, but is not limited thereto, for closing or blocking the channels to surely isolate the positive electrode layer 10 and the negative electrode layer 20 .

The above is the structure and material description of the positive electrode layer 10, the negative electrode layer 20, and the separator 30 of the composite lithium secondary battery of the present invention; the coating of the positive electrode layer 10 of the present invention will be described one by one with reference to FIGS. 3A to 6C. A specific embodiment of the area. Wherein, the partition coated positive electrode material of the present invention is preferably an olivine-structured lithium iron phosphate (LFP) or a lithium-containing ternary oxidation selected from lithium cobalt cobalt aluminate (LNCA) or lithium cobalt manganese oxide (LNCM). Further, the positive electrode material applied to the region 18 of the positive electrode layer 10 of the present invention which is closest to the outer end 16 is preferably lithium iron phosphate.

In order to facilitate the explanation of the following coating examples, it is defined that the coating of the lithium-containing ternary oxide (LNCA or LNCM) is the region 18A, and the coating of the lithium iron phosphate (LFP) is the region 18B. The blank region 19 is mainly formed into an elongated strip region and may be disposed in a longitudinal direction, a lateral direction, or an oblique direction to sandwich the positive electrode layer 10 The coating region is divided into a plurality of regions 18; wherein, the blank region defined as the side ends 13 and 14 of the positive electrode layer 10 vertically connected to each other as shown in FIG. 3A is defined as a longitudinal blank region 19A, which is vertically connected to the positive electrode layer 10 as shown in FIG. 5B. The blank area of the outer ends 15, 16 is in the form of a lateral blank area 19B, and the blank area of the side ends 13, 14 obliquely connected to the positive electrode layer 10 as shown in Fig. 4C is an oblique blank area 19C.

It should be understood that the above-mentioned "vertical" refers to a state of being nearly vertical or completely vertical; "vertical connection" and "connection" refer to a case where a blank area is extended and connected, as shown in FIG. 6A; the foregoing term is only used for Explain the setting status of the blank area, but the setting form of the blank area is not limited to this. In addition, the size and thickness of the positive electrode layer 10 drawn by the embodiment of the present invention are used to indicate and facilitate the explanation of the coating form. The layer structure size and thickness drawn by the drawing should not be used to explain or limit the case. Technology.

Embodiment 1:

As shown in FIG. 3A and FIG. 3B, the coating region of the positive electrode layer 10 is sequentially provided with an area 18A, a longitudinal blank area 19A and an area 18B from the inner end 15 toward the outer end 16, and the two areas are sequentially provided. A lithium ternary oxide and lithium iron phosphate are provided, and the side faces 11 and 12 of the positive electrode layer 10 are provided with a region 18A corresponding to the position of the positive electrode material, a longitudinal blank region 19A, and a region 18B. In this embodiment, the ratio of the area occupied by the area 18A and the area 18B may be adjusted according to the battery design requirements on the premise that the positions of the two sides 11 and 12 correspond to each other, or may be transmitted through the two sides 11 and 12 The same or different positive electrode materials may be coated in the corresponding regions 18 for the purpose of adjusting the area ratio.

Thereby, the composite lithium secondary battery of the present invention exhibits the characteristics of the lithium-containing ternary oxide at the initial discharge voltage through the arrangement of the coating region and the positive electrode material, that is, has a high operating voltage, and In the later stage of discharge, it also exhibits the characteristics of lithium-containing ternary oxides and lithium iron phosphate, which have high capacitance, safety and deep discharge resistance, and provide a combination of lithium iron phosphate and lithium-containing ternary oxides. Advantages of lithium secondary batteries.

Embodiment 2 :

As shown in FIG. 4A and FIG. 4B, the side faces 11, 12 of the positive electrode layer 10 are sequentially provided with two longitudinal blank regions 19A from the inner end 15 toward the outer end 16, and three coated regions separated therefrom, and A corresponding region on the side surface 11 and the side surface 12 of the positive electrode layer 10 is provided with a non-corresponding positive electrode material. As shown in FIG. 4B, a side region 18B, a region 18A and a region 18B are sequentially disposed on the side surface 11, that is, the three regions are sequentially provided with lithium iron phosphate, lithium-containing ternary oxide and lithium iron phosphate, and the side 12 is A region 18A, a region 18B and a region 18A are sequentially disposed, that is, the three regions are sequentially provided with a lithium-containing ternary oxide, lithium iron phosphate and a lithium-containing ternary oxide. In this embodiment, the proportion of the area occupied by the three regions can be adjusted according to the design requirements of the battery, and the coating position of the positive electrode material can also be adjusted according to requirements.

As shown in Fig. 4C, the form in which the vertical blank area 19A of Fig. 4A is changed to the oblique blank area 19C is shown. The arrangement of the oblique blank area 19C is not limited thereto, and the inner and outer ends 15 and 16 of the positive electrode layer 10 may be connected according to actual needs.

Embodiment 3 :

As shown in FIG. 5A and FIG. 5B, the side surfaces 11 and 12 of the positive electrode layer 10 are provided with a lateral blanking region 19B and two coating regions spaced apart therefrom, and are disposed on the side surface 11 and the side surface 12 of the positive electrode layer 10. The corresponding region does not correspond to the positive electrode material. As shown in FIG. 5B, a region 18A and a region 18B are sequentially disposed from the side end 13 toward the side end 14 on the side surface 11, that is, the two regions are sequentially provided with a lithium-containing ternary oxide and lithium iron phosphate, and the side 12 is provided. A region 18B and a region 18B are sequentially disposed, that is, lithium phosphate is disposed in the two regions. In this embodiment, the proportion of the area occupied by the two regions can be adjusted according to the design requirements of the battery, and the coating position of the positive electrode material can also be adjusted according to requirements. Wherein, since the positive electrode materials of the two regions on the side surface 12 are the same, the lateral blank region 19B on the side surface 12 can be eliminated in a visual manner to simplify the coating process.

Embodiment 4 :

As shown in FIG. 6A, FIG. 6B, and FIG. 6C, the side surfaces 11, 12 of the positive electrode layer 10 are provided with a lateral blank area 19B, and two longitudinal blank areas 19A connected between the lateral blank area 19B and the side end 14, and The coating zone is divided into four coating regions in a top three-down arrangement, and a portion of the positive electrode material that does not correspond to the corresponding region on the side surface 11 and the side surface 12 of the positive electrode layer 10 is provided. As shown in FIG. 6B and FIG. 6C, a region 18A is disposed on the side surface 11 adjacent to the positive electrode tab 17, and the lower three regions are surrounded by a region 18B, a region 18A and a region 18B, and the side surface 12 is adjacent to the positive electrode. An area 18A is provided at the ear 17, and the lower three areas are surrounded by an area 18A, an area 18B and an area 18A. In this embodiment, the proportion of the area occupied by the four regions can be adjusted according to the design requirements of the battery, and the coating position of the positive electrode material can also be adjusted according to requirements.

It should be understood that the coating form of the positive electrode material proposed by the present invention is not limited to the foregoing, and may be adjusted according to actual conditions, as long as the configuration of the coating region and the positive electrode material can achieve coating for improving the working efficiency of the lithium secondary battery. Forms are all within the scope of the invention.

Please refer to FIG. 7 and FIG. 8 to show the characteristic curves of the lithium secondary battery of the composite lithium secondary battery of the present invention and other positive electrode coated single positive electrode materials.

As shown in the LNCA curve of FIG. 7 and the LNCM curve of FIG. 8, the discharge characteristics of the two ternary positive electrode materials of nickel cobalt aluminum aluminate and lithium cobalt nickel manganate are sequentially shown. Among them, the ternary cathode material has the advantages of high working voltage and high energy density, and its working voltage range is about 3.2V~4.5V (normal state is about 3.7), and the capacitance is about 175~190 mAh/g; however, The discharge cut-off voltage of the ternary positive electrode material is relatively high, about 3V~2.7V. When over-discharged (discharge when the voltage is less than 3.0V), the excessively embedded lithium ions are permanently fixed in the crystal lattice and cannot be released any more. This leads to a shortened battery life and the disadvantage of not being able to discharge deeply.

As shown in the LFP curves of Figs. 7 and 8, the discharge characteristics of the lithium iron phosphate positive electrode material are shown. Among them, lithium iron phosphate does not perform as well as the above-mentioned ternary cathode material, and its working voltage range is about 2.5V~3.8V (normally about 3.2), and the capacitance is about 130~150 mAh. /g; However, the discharge cut-off voltage of lithium iron phosphate is significantly lower than that of the ternary cathode material, which can reach 2V, and has the advantage of being resistant to deep discharge and being charged immediately after overdischarge.

Therefore, the present invention differs in the combination of the combination of lithium iron phosphate and lithium nickel cobalt aluminate (curve LFP+LNCA of FIG. 7), lithium iron phosphate and lithium cobalt nickel manganate (curve LFP+LNCM of FIG. 8). The positive electrode material is coated on different regions of the same positive electrode surface to form a composite lithium secondary battery, and after the combination of the foregoing positive electrode materials is measured, the LFP+LNCA curve as shown in FIG. 7 and the LFP+LNCM curve as shown in FIG. 8 are measured. They are used to indicate the discharge characteristics of the LFP+LNCM hybrid lithium secondary battery and the LFP+LNCA composite lithium secondary battery, respectively.

It can be seen from the LFP+LNCA curve of FIG. 7 that the composite lithium secondary battery of the present invention passes through its LNCA positive electrode material, and the working voltage in the pre-discharge period is significantly higher than that in the lithium secondary battery coated only with LFP, and the working voltage is gently lowered. Non-instantaneous reduction, the performance of the previous working voltage and capacitance is similar to the LFP+LNCA curve. In the late stage of discharge, the LFP cathode material makes the working voltage of the composite lithium secondary battery of the present invention approach the LFP curve, but has the discharge cut-off voltage of the composite lithium secondary battery of the present invention down to about 2.6V, which is obvious. Below and beyond the discharge cut-off voltage range of the LNCA curve. As can be seen from the figure, the LFP+LNCA composite lithium secondary battery of the present invention has an operating voltage range of 4.5V to 2.7V, a capacitance greater than 175 mAh/g, and has a high operating voltage, high capacitance, and resistance to deep discharge and overdischarge. The technical effect of recovery can be restored immediately after charging.

It can be seen from the LFP+LNCM curve of FIG. 8 that the composite lithium secondary battery of the present invention passes through its LNCM positive electrode material, and the working voltage in the pre-discharge period is significantly higher than that in the lithium secondary battery coated only with LFP, and the working voltage is gently lowered. Non-instantaneous reduction, the performance of the previous working voltage and capacitance is similar to the LFP+LNCM curve. In the late stage of discharge, the LFP positive electrode material makes the working voltage of the composite lithium secondary battery of the present invention approach the LFP curve, but has the discharge cutoff voltage of the composite lithium secondary battery of the present invention down to about 2.5V, which is obvious. Below and beyond the discharge cut-off voltage range of the LNCM curve. As can be seen from the figure, the LFP+LNCM composite lithium secondary battery of the invention has an operating voltage range of 4.4V~2.6V, a capacitance greater than 185mAh/g, and has a high working voltage, high capacitance and resistance to deep discharge and overdischarge. The technical effect of recovery can be restored immediately after charging.

In summary, the present invention can achieve the above-mentioned various effects through the description of the above-mentioned composite lithium secondary battery, and has already met the patent application requirements, and has filed a patent application according to law, praying for review and early granting of patents. Real sense of virtue.

[prior art]
A‧‧‧Lithium secondary battery
A1‧‧‧core
A2‧‧‧ battery case (present invention)
10‧‧‧ positive layer
11, 12‧‧‧ side
13, 14‧‧‧ side
15‧‧‧Inside
16‧‧‧Outside
17‧‧‧ positive pole
18‧‧‧Area
18A‧‧‧Area
18B‧‧‧Area
18C‧‧‧Area
19‧‧‧Blank area
19A‧‧‧ Vertical blank area
19B‧‧‧Horizontal blank area
19C‧‧‧ oblique blank area
D‧‧‧ spaced wide
20‧‧‧negative layer
21, 22‧‧‧ side
23, 24‧‧‧ side
25‧‧‧Inside
26‧‧‧Outside
27‧‧‧Negative pole
28‧‧‧ Coating area
30‧‧‧Separator

Fig. 1A is a schematic perspective view showing a winding core of a conventional lithium secondary battery wound around a cylindrical battery case.

1B is a schematic perspective view showing a winding core of a conventional lithium secondary battery wound around a square battery case.

Fig. 2 is a perspective view showing the core of the composite lithium secondary battery of the present invention before winding.

Fig. 3A is a front elevational view showing a first embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 3B is a bottom plan view showing a first embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 4A is a front elevational view showing a second embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 4B is a bottom view showing a second embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 4C is a side elevational view showing a second embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 5A is a front elevational view showing a third embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 5B is a side elevational view showing a third embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 6A is a front elevational view showing a fourth embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 6B is a side elevational view showing a fourth embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 6C is a bottom view showing a second embodiment of a positive electrode coating form of the composite lithium secondary battery of the present invention.

Fig. 7 is a graph showing the battery characteristics of the composite lithium secondary battery (LFP+LNCA) of the present invention and a single positive electrode material (LFP, LNCA).

Fig. 8 is a graph showing the battery characteristics of the composite lithium secondary battery (LFP+LNCM) of the present invention and a single positive electrode material (LFP, LNCM).

10‧‧‧ positive layer

13, 14‧‧‧ side

15‧‧‧Inside

16‧‧‧Outside

17‧‧‧ positive pole

18A‧‧‧Area

18B‧‧‧Area

19A‧‧‧ Vertical blank area

Claims (10)

A composite lithium secondary battery having a core comprising at least one positive electrode layer, at least one negative electrode layer and a plurality of separators interposed between the positive electrode layer and the negative electrode layer, such that the positive electrode layer, the negative electrode layer and the The separator is laminated and wound to form the core; the positive electrode layer comprises a positive electrode material capable of intercalating and deintercalating the electrode reactant, the positive electrode layer has at least one positive electrode tab on one end thereof, and both sides of the positive electrode layer The positive electrode material is coated, and the positive electrode layer is defined as an inner end at one end of the center after being wound, and an outer end at one end of the outer side; the negative electrode layer includes a negative electrode material capable of inserting and extracting the electrode reactant, The negative electrode layer has at least one negative electrode tab on one side of the negative electrode layer, and the negative electrode material is coated on both sides thereof; the two sides of the positive electrode layer are correspondingly provided with a plurality of regions and at least one blank a region, each of which is coated with a positive electrode material, and a positive electrode material on both sides of the positive electrode layer is correspondingly disposed, and each of the regions and the positive electrode material thereon is separated by the blank region. blank The interval width is not less than 0.5mm; the positive electrode material having a coating of at least a region on the same side of the positive electrode layer and the positive electrode material different from the coating in other regions, the cathode material is selected from lithium iron phosphate (LiFePO ₄ , LFP) combined with lithium-containing ternary oxides. The composite lithium secondary battery according to claim 1, wherein the lithium-containing ternary oxide is selected from lithium nickel cobalt aluminate (LiNi _x Co _y Al _1-xy O ₂ ) or cobalt nickel Lithium manganate (LiNiCoMnO ₂ ). The composite lithium secondary battery according to claim 1 or 2, wherein the positive electrode material is an olivine-structured lithium iron phosphate (LFP) and a nickel-cobalt lithium aluminate (LiNi _x Co _y Al _1-xy). A combination of O ₂ ). The composite lithium secondary battery according to claim 3, which has an operating voltage range of 4.5V to 2.7V and a capacitance greater than 175 mAh/g. The composite lithium secondary battery according to claim 1 or 2, wherein the positive electrode material is a combination of lithium iron phosphate (LFP) and lithium cobalt nickel manganese oxide (LiNiCoMnO ₂ ) having an olivine structure. The composite lithium secondary battery according to claim 5, which has an operating voltage range of 4.4V to 2.6V and a capacitance of more than 185mAh/g. The composite lithium secondary battery according to claim 1, wherein the gap portion has a width of 5 cm or less and 0.5 mm or more. The composite lithium secondary battery according to claim 1, wherein the negative electrode material is selected from a graphite-based or coke-based carbon material. The composite lithium secondary battery according to claim 1, wherein the positive electrode material applied to the region of the positive electrode layer closest to the outer end is lithium iron phosphate (LFP). The composite lithium secondary battery according to claim 1, wherein the blank area defining the both ends of the positive electrode layer is a longitudinal blank area, and the blank area connecting the inner end and the outer end of the positive electrode layer is one a horizontal blank area, the blank area obliquely connecting the two side ends or the inner side and the outer side of the positive electrode layer is an oblique blank area, and the longitudinal blank area and the horizontal blank area are correspondingly disposed on the side surface of the positive electrode layer And/or the oblique blank area separates the plurality of areas.