Patent Publication Number: US-2022223923-A1

Title: Battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase entry of International Application No. PCT/CN2020/077640, filed on Mar. 3, 2020 and entitled “BATTERY”, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates to the electrochemical field, and in particular, to a battery. 
     BACKGROUND 
     A lithium battery is widely applied in portable electronic devices by virtue of advantages such as a high voltage, a high specific energy, and a long cycle life. Rapid development of the portable electronic devices imposes higher requirements on the battery. However, currently, most of jelly-roll battery cells have a problem of poor interface flatness, thereby affecting a current density distribution inside the battery cells. In addition, 1,3-propanesultone (1,3-propanesultone, PS) serving as a film-forming additive in an electrolytic solution is a carcinogen. If such additive is fully removed from the electrolytic solution, film formation on negative positive electrodes will be affected, and therefore, performance of the battery such as cycle performance and high-temperature storage performance will be affected. If a new film-forming additive is developed to replace the 1,3-propanesultone, manufacturing costs of the battery will increase significantly. 
     SUMMARY 
     In view of the foregoing situation, it is necessary to provide a battery to solve the foregoing problems. 
     A battery is disclosed, including an electrode assembly, a package accommodating the electrode assembly, an electrolytic solution contained in the package, a first tab, and a second tab. The electrode assembly is formed by winding a first electrode plate and a second electrode plate that are stacked. The first electrode plate includes a first current collector and a first active material layer disposed on both sides of the first current collector. 
     The electrolytic solution includes a lithium salt, an organic ester solvent, and a film-forming additive. The film-forming additive includes 1,3-propanesultone. A weight percent of the 1,3-propanesultone in the electrolytic solution is 0%-1%. 
     The first current collector includes a first blank region, a first single-surface-coated region, and a first double-surface-coated region disposed sequentially. The first blank region includes a first planar region extending from a winding initiation end of the first electrode plate to a first bend of the first electrode plate, and a first bent region connected to the first planar region. The first single-surface-coated region includes a second bent region and a second planar region connected between the first bent region and the second bent region; the second planar region is opposite to the first planar region. The second bent region is opposite to the first bent region. 
     The first tab is disposed in the first planar region. The second tab is disposed on the second electrode plate. 
     The battery further includes a first filler. The first filler is disposed in the first planar region or the second planar region. Projections of the first filler, the first tab, and the second tab in a thickness direction of the electrode assembly do not overlap. 
     Optionally, the second electrode plate includes a second current collector and a second active material layer disposed on both sides of the second current collector. The second current collector includes a second blank region and a second double-surface-coated region disposed sequentially. The second blank region includes a third planar region extending from a winding initiation end of the second electrode plate to a first bend of the second electrode plate, and a third bent region connected to the third planar region. The third planar region is opposite to the first planar region. The third bent region is opposite to the second bent region. The second tab is disposed on the third planar region. 
     Optionally, the first filler includes a first filler portion, a second filler portion, and a third filler portion. The first filler portion is disposed in the first bent region. The second filler portion is disposed in the second planar region. The third filler portion is disposed in the second bent region. 
     Optionally, the first tab includes a first end towards the first bent region and a second end facing opposite from the first end. The second tab includes a third end towards the first bent region and a fourth end facing opposite from the third end. In a width direction of the electrode assembly, a vertical distance from an end of the first filler portion to the third end is 0 mm-4 mm, the end of the first filler portion is towards the second bent region, and a vertical distance from an end of the second filler portion to the fourth end is 0 mm-4 mm, the end of the second filler portion is towards the first bent region, and a vertical distance from an end of the second filler portion to the first end is 0 mm-4 mm, the end of the second filler portion is towards the second bent region, and a vertical distance from an end of the third filler portion to the second end is 0 mm-4 mm, the end of the third filler portion is towards the first bent region. 
     Optionally, the second current collector further includes a second single-surface-coated region connected to the second double-surface-coated region and a third blank region connected to the second single-surface-coated region. The second single-surface-coated region and the third blank region are located on an outermost coil of the electrode assembly. The second single-surface-coated region includes a fourth bent region opposite to the second bent region; and the third blank region includes a fifth bent region opposite to the first bent region. 
     Optionally, the battery further includes a second filler. The second filler includes a fourth filler portion and a fifth filler portion. The fourth filler portion is disposed in the fourth bent region. The fifth filler portion is disposed in the fifth bent region. Projections of the fourth filler portion, the fifth filler portion, the first tab, and the second tab in the thickness direction of the electrode assembly do not overlap. 
     Optionally, the first tab includes a first end towards the first bent region and a second end facing opposite from the first end. The second tab includes a third end towards the first bent region and a fourth end facing opposite from the third end. In a width direction of the electrode assembly, a vertical distance from an end of the fourth filler portion to the third end is 0 mm-4 mm, the end of the fourth filler portion is towards the second bent region, and a vertical distance from an end of the fifth filler portion to the second end is 0 mm-4 mm, the end of the fifth filler portion is towards the first bent region. 
     Optionally, the battery further includes a second filler. The first filler includes a first portion, a second portion, and a third portion. The second filler includes a fourth portion connected between the first portion and the second portion and a fifth portion connected between the second portion and the third portion. The fourth portion is disposed on a surface facing opposite from the first tab in the first planar region. The fifth portion is disposed on a surface facing opposite from the second tab in the first planar region. The first portion and the second portion are disposed in the first planar region. The third portion is disposed in the first bent region. 
     Optionally, in the thickness direction of the electrode assembly, A1—B—C≤20 μm, A2—B—C≤20 μm, A3—B—D≤20 μm; wherein A1 is a thickness of the first portion, A2 is a thickness of the second portion, A3 is a thickness of the third portion, B is a thickness of the first tab, C is a thickness of the fourth portion, and D is a thickness of the fifth portion. 
     Optionally, the battery further includes a third filler. The third filler includes a first blank current collector opposite to the first bent region and a second blank current collector opposite to the first bent region. The first blank current collector is disposed at an end of the first planar region, the end of the first planar region is away from the first bent region, and is bent against the first planar region. The second blank current collector is disposed at an end of the first double-surface-coated region, the end of the first double-surface-coated region is away from the first blank region, and is bent against the first double-surface-coated region. Projections of the first blank current collector, the second blank current collector, the first tab, and the second tab in the thickness direction of the electrode assembly do not overlap. 
     Optionally, the first tab includes a first end towards the first bent region and a second end facing opposite from the first end. The second tab includes a third end towards the first bent region and a fourth end facing opposite from the third end. In a width direction of the electrode assembly, a vertical distance from an end of the first blank current collector to the second end is 0 mm-4 mm, the end of the first blank current collector is towards the first bent region, and a vertical distance from an end of the second blank current collector to the second end is 0 mm-4 mm, the end of the second blank current collector is towards the first bent region. 
     Optionally, the first filler includes a first coating, a second coating, a third coating, and a fourth coating. The first coating is disposed in the first planar region. The second coating is disposed in the first bent region. The third coating is disposed in the second planar region. The fourth coating is disposed in the second bent region. 
     Optionally, the first tab includes a first end towards the first bent region and a second end facing opposite from the first end. The second tab includes a third end towards the first bent region and a fourth end facing opposite from the third end. In a width direction of the electrode assembly, a vertical distance from an end of the first coating to the fourth end is 0 mm-4 mm, the end of the first coating is towards the first bent region, and a vertical distance from an end of the first coating to the first end is 0 mm-4 mm, the end is away from the first bent region, and a vertical distance from an end of the second coating to the third end is 0 mm-4 mm, the end of the second coating is towards the second bent region, and a vertical distance from an end of the third coating to the fourth end is 0 mm-4 mm, the end of the third coating is towards the first bent region, and a vertical distance from an end of the third coating to the first end is 0 mm-4 mm, the end of the third coating is away from the first bent region, and a vertical distance from an end of the fourth coating to the second end is 0 mm-4 mm, the end of the fourth coating is towards the first bent region. 
     Optionally, the organic ester solvent includes ethylene carbonate, propylene carbonate, ethyl methyl carbonate, and diethyl carbonate. A weight percent of the ethylene carbonate in the electrolytic solution is 5%-23%. A weight percent of the propylene carbonate in the electrolytic solution is 0%-30%. A weight percent of the ethyl methyl carbonate in the electrolytic solution is 0%-60%. A weight percent of the diethyl carbonate in the electrolytic solution is 0%-60%. 
     Optionally, the film-forming additive further includes vinylene carbonate, halogenated carbonate, and lithium difluorophosphate. A weight percent of the vinylene carbonate in the electrolytic solution is 0%-2%. A weight percent of the halogenated carbonate in the electrolytic solution is 0%-4%. A weight percent of the lithium difluorophosphate in the electrolytic solution is 0%-2%. 
     In conclusion, PS is a carcinogenic substance and is included in a candidate list of Substances of Very High Concern (SVHC) by the EU Reach regulations. Toys and other products that come into direct contact with children are particularly sensitive to the content of PS. Demand for environmentally friendly lithium-ion batteries with a low PS content is urgent. However, PS is an excellent film-forming additive. Insufficiency of PS will affect film formation of a solid electrolyte interface (Solid electrolyte interface, SEI), and affect battery performance such as cycle performance and high-temperature storage performance. By using the film-forming additives such as vinylene carbonate, halogenated carbonate, and lithium difluorophosphate, this application strengthens film formation on negative and positive electrodes, makes up for insufficient formation of the SEI film due to a lower content of PS. In addition, a current density is critical to the formation of the SEI film. The formation of the SEI film includes two processes: crystal nuclei formation, and crystal nuclei growth. When the current density is relatively high, the crystal nuclei are formed at a high speed, thereby leading to a loose structure of the SEI film and weak adhesion to a surface of the negative electrode. When an internal structure of the electrode assembly is unevenly distributed, different internal positions receive different forces during chemical formation, the current density is distributed unevenly, and the current density is too high in some local positions. Consequently, the formed SEI film is loose, unstable and poorly consistent. The disposed first filler compensates for a thickness difference between a tab part and a non-tab part arising from the disposed first tab and second tab, thereby improving flatness of the internal structure of the electrode assembly, facilitating even distribution of the current density inside the electrode assembly, and helping to form a consistent and stable SEI film. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic structural diagram of a battery according to an embodiment of this application; 
         FIG. 2  is a schematic structural diagram of the electrode assembly shown in  FIG. 1 ; 
         FIG. 3  is schematic structural diagram of a first electrode plate shown in  FIG. 2 ; 
         FIG. 4  is schematic structural diagram of a second electrode plate shown in  FIG. 2 ; 
         FIG. 5  is a schematic structural diagram of an electrode assembly according to an embodiment of this application; 
         FIG. 6  is schematic structural diagram of a first electrode plate shown in  FIG. 5 ; 
         FIG. 7  is a schematic structural diagram of an electrode assembly according to another embodiment of this application; 
         FIG. 8  is a schematic structural diagram of an electrode assembly according to still another embodiment of this application; 
         FIG. 9  is schematic structural diagram of a first electrode plate shown in  FIG. 8 ; and 
         FIG. 10  is a schematic structural diagram of a battery according to another embodiment of this application; 
     
    
    
     REFERENCE NUMERALS 
     Battery  100   
     Electrode assembly  10   
     First electrode plate  11   
     First current collector  111   
     First active material layer  112   
     First blank region  113   
     First planar region  1131   
     First bent region  1132   
     First single-surface-coated region  114   
     Second bent region  1141   
     Second planar region  1142   
     First double-surface-coated region  115   
     Second electrode plate  12   
     Second current collector  121   
     Second active material layer  122   
     Second blank region  123   
     Third planar region  1231   
     Third bent region  1232   
     Second double-surface-coated region  124   
     Second single-surface-coated region  125   
     Fourth bent region  1251   
     Third blank region  126   
     Fifth bent region  1261   
     Separator  13   
     Package  20   
     Electrolytic solution  30   
     First tab  40   
     First end  401   
     Second end  402   
     Second tab  50   
     Third end  501   
     Fourth end  502   
     First filler  60   
     First filler portion  601   a    
     Second filler portion  602   a    
     Third filler portion  603   a    
     First portion  601   b    
     Second portion  602   b    
     Third portion  603   b    
     First coating  601   c    
     Second coating  602   c    
     Third coating  603   c    
     Fourth coating  604   c    
     Second filler  70   
     Fourth filler portion  701   a    
     Fifth filler portion  702   a    
     Fourth portion  701   b    
     Fifth portion  702   b    
     Third filler  80   
     First blank current collector  801   
     Second blank current collector  802   
     First bonding portion  901   
     Second bonding portion  902   
     Third bonding portion  903   
     Fourth bonding portion  904   
     Fifth bonding portion  905   
     This application is further described below with reference to the following specific embodiments and the foregoing drawings. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The following clearly and fully describes the technical solutions in the embodiments of this application with reference to the drawings hereof. Apparently, the described embodiments are merely a part of but not all of the embodiments of this application. All other embodiments derived by a person of ordinary skill in the art based on the embodiments of this application without making any creative efforts shall fall within the protection scope of this application. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meanings as usually understood by a person skilled in the technical field of this application. The terms used in the specification of this application herein are merely intended for describing specific embodiments but are not intended to limit this application. 
     The following describes some embodiments of this application in detail with reference to drawings. To the extent that no conflict occurs, the following embodiments and the features in the embodiments may be combined with each other. 
     Referring to  FIG. 1  and  FIG. 10 , an embodiment of this application provides a battery  100 . The battery  100  includes an electrode assembly  10 , a package  20  accommodating the electrode assembly  10 , an electrolytic solution  30  contained in the package  20 , a first tab  40 , a second tab  50 , and a first filler  60 . 
     The electrolytic solution  30  includes a lithium salt, an organic ester solvent, and a film-forming additive. The film-forming additive includes 1,3-propanesultone (PS). In the electrolytic solution  30 , a weight percent of the 1,3-propanesultone is 0%-1%. 
     In an embodiment, the organic ester solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). In the electrolytic solution  30 , a weight percent of the ethylene carbonate is 5%-23%, a weight percent of the propylene carbonate is 0%-30%, a weight percent of the ethyl methyl carbonate is 0%-60%, and a weight percent of the diethyl carbonate is 0%-60%. 
     Further, the film-forming additive further includes vinylene carbonate (VC), halogenated carbonate, and lithium difluorophosphate (LiPO 2 F 2 ). In the electrolytic solution  30 , a weight percent of the vinylene carbonate is 0%-2%, a weight percent of the halogenated carbonate is 0%-4%, and a weight percent of the lithium difluorophosphate is 0%-2%. 
     Referring to  FIG. 1  and  FIG. 2 , the electrode assembly  10  is formed by winding a first electrode plate  11  and a second electrode plate  12  that are stacked. The first tab  40  is disposed on the first electrode plate  11 . The second tab  50  is disposed on the second electrode plate  12 . 
     Referring to  FIG. 3 , the first electrode plate  11  includes a first current collector  111  and a first active material layer  112  disposed on both sides of the first current collector  111 . 
     Referring to  FIG. 3 , the first current collector  111  includes a first blank region  113 , a first single-surface-coated region  114 , and a first double-surface-coated region  115  that are disposed sequentially. The first active material layer  112  is disposed on neither side of the first blank region  113 . The first active material layer  112  is not disposed on a surface that, in the first single-surface-coated region  114 , faces a center of the electrode assembly  10  (referring to  FIG. 3 ). The first active material layer  112  is disposed on both sides of the first double-surface-coated region  115 . 
     Referring to  FIG. 2 , the first blank region  113  includes a first planar region  1131  extending from a winding initiation end of the first electrode plate  11  to a first bend of the first electrode plate  11 , and a first bent region  1132  connected to the first planar region  1131 . The first single-surface-coated region  114  includes a second bent region  1141  and a second planar region  1142  connected between the first bent region  1132  and the second bent region  1141 . The second planar region  1142  is opposite to the first planar region  1131 . The second bent region  1141  is opposite to the first bent region  1132 . The first tab  40  is disposed on the first planar region  1131 . 
     In an embodiment, the first tab  40  is disposed on a surface facing opposite from the center of the electrode assembly  10  in the first planar region  1131 . 
     Alternatively, the first tab  40  is disposed on a surface facing the center of the electrode assembly  10  in the first planar region  1131 . 
     Referring to  FIG. 4 , the second electrode plate  12  includes a second current collector  121  and a second active material layer  122  disposed on both sides of the second current collector  121 . 
     The second current collector  121  includes a second blank region  123  and a second double-surface-coated region  124  disposed sequentially. The second active material layer  122  is disposed on neither side of the second blank region  123 . The second active material layer  122  is disposed on both sides of the second double-surface-coated region  124 . 
     Referring to  FIG. 2 , the second blank region  123  includes a third planar region  1231  extending from a winding initiation end of the second electrode plate  12  to a first bend of the second electrode plate  12 , and a third bent region  1232  connected to the third planar region  1231 . The third planar region  1231  is opposite to the first planar region  1131 . The third bent region  1232  is opposite to the second bent region  1141 . The second tab  50  is disposed on the third planar region  1231 . 
     In an embodiment, the second tab  50  is disposed on a surface facing opposite from the center of the electrode assembly  10  in the third planar region  1231 . 
     Alternatively, the second tab  50  is disposed on a surface facing the center of the electrode assembly  10  in the third planar region  1231 . 
     Further, referring to  FIG. 4 , the second current collector  121  further includes a second single-surface-coated region  125  connected to the second double-surface-coated region  124 , and a third blank region  126  connected to the second single-surface-coated region  125 . The second single-surface-coated region  125  and the third blank region  126  are located on an outermost coil of the electrode assembly  10 . The second active material layer  122  is not disposed on a surface thatfacing opposite from the center of the electrode assembly  10  in the second single-surface-coated region  125 . The second active material layer  122  is disposed on neither side of the third blank region  126 . 
     Referring to  FIG. 2  and  FIG. 4 , the second single-surface-coated region  125  includes a fourth bent region  1251  opposite to the second bent region  1141 . The third blank region  126  includes a fifth bent region  1261  opposite to the first bent region  1132 . 
     Referring to  FIG. 2 , the first tab  40  includes a first end  401  towards the first bent region  1132  and a second end  402  facing opposite from the first end  401 . The second tab  50  includes a third end  501  towards the first bent region  1132  and a fourth end  502  facing opposite from the third end  501 . 
     Referring to  FIG. 2 ,  FIG. 5 ,  FIG. 7 , and  FIG. 8 , the first filler  60  is disposed in the first planar region  1131  or the second planar region  1142 . Projections of the first filler  60 , the first tab  40 , and the second tab  50  in the thickness direction (that is, an X-axis direction) of the electrode assembly  10  do not overlap. In this way, the disposed first filler  60  compensates for a thickness difference between a tab part and a non-tab part arising from the disposed first tab  40  and second tab  50 , thereby improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . The first filler  60  may be a green adhesive or a hot-melt adhesive. 
     In this embodiment, referring to  FIG. 1  and  FIG. 2 , the first filler  60  includes a first filler portion  601   a , a second filler portion  602   a , and a third filler portion  603   a . The first filler portion  601   a  is disposed in the first bent region  1132 . The second filler portion  602   a  is disposed in the second planar region  1142 . The third filler portion  603   a  is disposed in the second bent region  1141 . In this way, the disposed second filler portion  602   a  compensates for a thickness difference between a tab part and a non-tab part arising from the disposed first tab  40  and second tab  50 , thereby improving flatness of the internal structure of the electrode assembly  10 , and facilitating even distribution of the current density inside the electrode assembly  10 . In addition, the disposed first filler portion  601   a  and the third filler portion  603   a  compensates for a thickness difference in the bent region arising from the winding of the electrode plate, thereby effectively improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . 
     Referring to  FIG. 2 , in the width direction (that is, a Y-axis direction) of the electrode assembly  10 , a vertical distance d 1  from an end of the first filler portion  601   a  to the third end  501  is 0 mm-4 mm, the end of the first filler portion  601   a  is towards the second bent region  1141 , and a vertical distance d 2  from an end of the second filler portion  602   a  to the fourth end  502  is 0 mm-4 mm, the end of the second filler portion  602   a  is towards the first bent region  1132 , and a vertical distance d 3  from an end of the second filler portion  602   a  to the first end  401  is 0 mm-4 mm, the end of the second filler portion  602   a  is towards the second bent region  1141 , and a vertical distance d 4  from an end of the third filler portion  603   a  to the second end  402  is 0 mm-4 mm, the end of the third filler portion  603   a  is towards the first bent region  1132 . 
     Further, referring to  FIG. 2 , a separator  13  is further disposed between the first electrode plate  11  and the second electrode plate  12 . Also referring to  FIG. 3 , the battery  100  further includes a first bonding portion  901  and a second bonding portion  902 . The first bonding portion  901  wraps the first tab  40 . The second bonding portion  902  is disposed in the first single-surface-coated region  114 , and located on a side of the third filler portion  603   a , the side is away from the second filler portion  602   a . The disposed first bonding portion  901  and second bonding portion  902  are configured to protect the separator  13 , and prevent burrs on the first tab  40  and the first current collector  111  from piercing the separator  13 . 
     In an embodiment, referring to  FIG. 1 , the battery  100  further includes a second filler  70 . The second filler  70  includes a fourth filler portion  701   a  and a fifth filler portion  702   a . The fourth filler portion  701   a  is disposed in the fourth bent region  1251 , and the fifth filler portion  702   a  is disposed in the fifth bent region  1261 . Projections of the fourth filler portion  701   a , the fifth filler portion  702   a , the first tab  40 , and the second tab  50  on the electrode assembly  10  do not overlap. In this way, the disposed second filler  70  compensates for a thickness difference in the bent region arising from the winding of the electrode plate, thereby effectively improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . The second filler  70  may be a green adhesive or a hot-melt adhesive. 
     Referring to  FIG. 2 , in the width direction of the electrode assembly  10 , the vertical distance d 1  from an end of the fourth filler portion  701   a  to the third end  501  is 0 mm-4 mm, the end of the fourth filler portion  701   a  is towards the second bent region  1141 , and the vertical distance d 4  from an end of the fifth filler portion  702   a  to the second end  402  is 0 mm-4 mm, the end of the fifth filler portion  702   a  is towards the first bent region  1132 . 
     Further, referring to  FIG. 4 , the battery  100  further includes a third bonding portion  903 , a fourth bonding portion  904 , and a fifth bonding portion  905 . The third bonding portion  903  wraps the second tab  50 . The fourth bonding portion  904  is disposed in the second single-surface-coated region  125 , and located on a side of the fourth filler portion  701   a , the side is away from the fifth filler portion  702   a . The fifth bonding portion  905  is disposed on a surface facing opposite from the fifth filler portion  702   a  in the third blank region  126 . The disposed third bonding portion  903 , fourth bonding portion  904 , and fifth bonding portion  905  are configured to protect the separator  13 , and prevent burrs on the second tab  50  and the second current collector  121  from piercing the separator  13 . 
     In another embodiment, referring to  FIG. 5  and  FIG. 6 , the first filler  60  includes a first portion  601   b , a second portion  602   b , and a third portion  603   b . The battery  100  further includes a second filler  70 . The second filler  70  includes a fourth portion  701   b  connected between the first portion  601   b  and the second portion  602   b , and a fifth portion  702   b  connected between the second portion  602   b  and the third portion  603   b . The fourth portion  701   b  is disposed on a surface facing opposite from the first tab  40  in the first planar region  1131 . The fifth portion  702   b  is disposed on a surface facing opposite from the second tab  50  in the first planar region  1131 . The first portion  601   b  and the second portion  602   b  are disposed in the first planar region  1131 . The third portion  603   b  is disposed in the first bent region  1132 . In this way, the disposed first portion  601   b , second portion  602   b , fourth portion  701   b , and fifth portion  702   b  compensate for the thickness difference between the tab part and the non-tab part arising from the disposed first tab  40  and second tab  50 , thereby improving the flatness of the internal structure of the electrode assembly  10 , and facilitating even distribution of the current density inside the electrode assembly  10 . In addition, the disposed third portion  603   b  compensates for the thickness difference in the bent region arising from the winding of the electrode plate, thereby effectively improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . 
     In the thickness direction of the electrode assembly  10 , 
       A 1 −B−C≤20 μm;
 
       A 2 −B−C≤20 μm; and
 
       A 3 −B−D≤20 μm.
 
     In the formulas above, A 1  is a thickness of the first portion, A 2  is a thickness of the second portion, A 3  is a thickness of the third portion, B is a thickness of the first tab  40 , C is a thickness of the fourth portion  701   b , and D is a thickness of the fifth portion  702   b.    
     In other embodiments, referring to  FIG. 7 , the battery  100  further includes a third filler  80 . The third filler  80  includes a first blank current collector  801  opposite to the first bent region  1132  and a second blank current collector  802  opposite to the first bent region  1132 . The first blank current collector  801  is disposed at an end of the first planar region  1131 , the end of the first planar region  1131  is away from the first bent region  1132 , and is bent against the first planar region  1131 . The second blank current collector  802  is disposed at an end of the first double-surface-coated region  115 , the end of the first double-surface-coated region  115  is away from the first blank region  113 , and is bent against the first double-surface-coated region  115 . Projections of the first blank current collector  801 , the second blank current collector  802 , the first tab  40 , and the second tab  50  in the thickness direction of the electrode assembly  10  do not overlap. In this way, the disposed third filler  80  compensates for a thickness difference in the bent region arising from the winding of the electrode plate, thereby effectively improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . 
     In the width direction of the electrode assembly  10 , a vertical distance e 1  from an end of the first blank current collector  801  to the second end  402  is 0 mm-4 mm, the end of the first blank current collector  801  is towards the first bent region  1132 , and a vertical distance e 2  from an end of the second blank current collector  802  to the second end  402  is 0 mm-4 mm, the end of the second blank current collector  802  is towards the first bent region  1132 . 
     In another embodiment, referring to  FIG. 8  and  FIG. 9 , the first filler  60  includes a first coating  601   c , a second coating  602   c , a third coating  603   c , and a fourth coating  604   c . The first coating  601   c  is disposed in the first planar region  1131 . The second coating  602   c  is disposed in the first bent region  1132 . The third coating  603   c  is disposed in the second planar region  1142 . The fourth coating  604   c  is disposed in the second bent region  1141 . In this way, the disposed first coating  601   c  and third coating  603   c  compensate for the thickness difference between the tab part and the non-tab part arising from the disposed first tab  40  and second tab  50 , thereby improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . In addition, the disposed second coating  602   c  and third coating  603   c  compensate for the thickness difference in the bent region arising from the winding of the electrode plate, thereby effectively improving flatness of the internal structure of the electrode assembly  10  and facilitating even distribution of the current density inside the electrode assembly  10 . 
     In the width direction of the electrode assembly  10 , a vertical distance f 1  from an end of the first coating  601   c  to the fourth end  502  is 0 mm-4 mm, the end of the first coating  601   c  is towards the first bent region  1132 , and a vertical distance f 2  from an end of the first coating  601   c  to the first end  401  is 0 mm-4 mm, the end of the first coating  601   c  is away from the first bent region  1132 , and a vertical distance f 3  from an end of the second coating  602   c  to the third end  501  is 0 mm-4 mm, the end of the second coating  602   c  is towards the second bent region  1141 , and a vertical distance f 1  from an end of the third coating  603   c  to the fourth end  502  is 0 mm-4 mm, the end of the third coating  603   c  is towards the first bent region  1132 , and a vertical distance f 2  from an end of the third coating  603   c  to the first end  401  is 0 mm-4 mm, the end of the third coating  603   c  is away from the first bent region  1132 , and a vertical distance f 4  from an end of the fourth coating  604   c  to the second end  402  is 0 mm-4 mm, the end of the fourth coating  604   c  is towards the first bent region  1132 . 
     The following describes the battery  100  in this application in detail with reference to embodiments. 
     Embodiment 1 
     Referring to  FIG. 9  and  FIG. 10 , the battery  100  includes an electrode assembly  10 , a package  20  accommodating the electrode assembly  10 , an electrolytic solution  30  contained in the package  20 , a first tab  40 , a second tab  50 , and a first filler  60 . 
     The electrolytic solution  30  includes a lithium salt, an organic ester solvent, and a film-forming additive. The organic ester solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). In the electrolytic solution  30 , a weight percent of the ethylene carbonate is 5%-23%, a weight percent of the propylene carbonate is 0%-30%, a weight percent of the ethyl methyl carbonate is 0%-60%, and a weight percent of the diethyl carbonate is 0%-60%. The film-forming additive includes 1,3-propanesultone (PS), vinylene carbonate (VC), halogenated carbonate (FEC), and lithium difluorophosphate (LiPO 2 F 2 ). In the electrolytic solution  30 , a weight percent of the 1,3-propanesultone is 0%-1%, a weight percent of the vinylene carbonate is 0%-2%, a weight percent of the halogenated carbonate is 0%-4%, and a weight percent of the lithium difluorophosphate is 0%-2%. 
     Referring to  FIG. 3  and  FIG. 4 , the electrode assembly  10  is formed by winding a first electrode plate  11  and a second electrode plate  12  that are stacked. 
     The first electrode plate  11  includes a first current collector  111  and a first active material layer  112  disposed on both sides of the first current collector  111 . 
     The first current collector  111  includes a first blank region  113 , a first single-surface-coated region  114 , and a first double-surface-coated region  115  that are disposed sequentially. 
     Referring to  FIG. 10 , the first blank region  113  includes a first planar region  1131  extending from a winding initiation end of the first electrode plate  11  to a first bend of the first electrode plate  11 , and a first bent region  1132  connected to the first planar region  1131 . The first single-surface-coated region  114  includes a second bent region  1141  and a second planar region  1142  connected between the first bent region  1132  and the second bent region  1141 . The second planar region  1142  is opposite to the first planar region  1131 . The second bent region  1141  is opposite to the first bent region  1132 . 
     The first tab  40  is disposed on a surface facing opposite from a center of the electrode assembly  10  in the first planar region  1131 . The second tab  50  is disposed on the second electrode plate  12 . 
     Referring to  FIG. 9  and  FIG. 10 , the first filler  60  includes a first coating  601   c , a second coating  602   c , a third coating  603   c , and a fourth coating  604   c . The first coating  601   c  is disposed in the first planar region  1131 . The second coating  602   c  is disposed in the first bent region  1132 . The third coating  603   c  is disposed in the second planar region  1142 . The fourth coating  604   c  is disposed in the second bent region  1141 . Projections of the first filler  60 , the first tab  40 , and the second tab  50  in the thickness direction of the electrode assembly  10  do not overlap. 
     In Embodiment 1, the first tab  40  includes a first end  401  towards the first bent region  1132  and a second end  402  facing opposite from the first end  401 . The second tab  50  includes a third end  501  towards the first bent region  1132  and a fourth end  502  facing opposite from the third end  501 . 
     Referring to  FIG. 8 , in the width direction of the electrode assembly, a vertical distance from an end of the first coating  601   c  to the fourth end  502  is 0 mm-4 mm, the end of the first coating  601   c  is towards the first bent region  1132 , and a vertical distance from an end of the first coating  601   c  to the first end  401  is 0 mm-4 mm, the end of the first coating  601   c  is away from the first bent region  1132 , and a vertical distance from an end of the second coating  602   c  to the third end  501  is 0 mm-4 mm, the end of the second coating  602   c  is towards the second bent region  1141 , and a vertical distance from an end of the third coating  603   c  to the fourth end  502  is 0 mm-4 mm, the end of the third coating  603   c  is towards the first bent region  1132 , and a vertical distance from an end of the third coating  603   c  to the first end  401  is 0 mm-4 mm, the end of the third coating  603   c  is away from the first bent region  1132 , and a vertical distance from an end of the fourth coating  604   c  to the second end  402  is 0 mm-4 mm, the end of the fourth coating  604   c  is towards the first bent region  1132 . 
     Embodiment 2 
     Embodiment 2 differs from Embodiment 1 in the first filler  60  in Embodiment 2, and differs in that the battery  100  in Embodiment 2 further includes a second filler  70 . 
     In Embodiment 2, referring to  FIG. 5  and  FIG. 6 , the first filler  60  includes a first portion  601   b , a second portion  602   b , and a third portion  603   b . The second filler  70  includes a fourth portion  701   b  connected between the first portion  601   b  and the second portion  602   b , and a fifth portion connected between the second portion  602   b  and the third portion  603   b . The fourth portion  701   b  is disposed on a surface that, in the first planar region  1131 , faces opposite from the first tab  40 . The fifth portion  702   b  is disposed on a surface facing opposite from the second tab  50  in the first planar region  1131 . The first portion  601   b  and the second portion  602   b  are disposed in the first planar region  1131 . The third portion  603   b  is disposed in the first bent region  1132 . 
     In Embodiment 2, in the thickness direction of the electrode assembly  10 , A 1 −B−C≤20 μm, A 2 −B−C≤20 μm, and A 3 −B−D≤20 μm. 
     In the formulas above, A 1  is a thickness of the first portion  601   b , A 2  is a thickness of the second portion  602   b , A 3  is a thickness of the third portion  603   b , B is a thickness of the first tab  40 , C is a thickness of the fourth portion  701   b , and D is a thickness of the fifth portion  702   b.    
     Embodiment 3 
     Embodiment 3 differs from Embodiment 1 in the first filler  60  in Embodiment 3, and differs in that the battery  100  in Embodiment 3 further includes a second filler  70 . 
     In Embodiment 3, referring to  FIG. 4 , the second electrode plate  12  includes a second current collector  121  and a second active material layer  122  disposed on both sides of the second current collector  121 . 
     The second current collector  121  includes a second blank region  123 , a second double-surface-coated region  124 , a second single-surface-coated region  125 , and a third blank region  126  disposed sequentially. The second single-surface-coated region  125  and the third blank region  126  are located on an outermost coil of the electrode assembly. 
     Referring to  FIG. 1  and  FIG. 2 , the second blank region  123  includes a third planar region  1231  extending from a winding initiation end of the second electrode plate  12  to a first bend of the second electrode plate  12 , and a third bent region  1232  connected to the third planar region  1231 . The third planar region  1231  is opposite to the first planar region  1131 . The third bent region  1232  is opposite to the first bent region  1132 . The second tab  50  is disposed on a surface facing opposite from the center of the electrode assembly  10  in the third planar region  1231 . 
     The second single-surface-coated region  125  includes a fourth bent region  1251  opposite to the second bent region  1141 . 
     The third blank region  126  includes a fifth bent region  1261  opposite to the first bent region  1132 . 
     Referring to  FIG. 1  and  FIG. 2 , the first filler  60  includes a first filler portion  601   a , a second filler portion  602   a , and a third filler portion  603   a . The first filler portion  601   a  is disposed in the first bent region  1132 . The second filler portion  602   a  is disposed in the second planar region  1142 . The third filler portion  603   a  is disposed in the second bent region  1141 . 
     In the width direction of the electrode assembly, a vertical distance from an end of the first filler portion  601   a  to the third end  501  is 0 mm-4 mm, the end of the first filler portion  601   a  is towards the second bent region  1141 , and a vertical distance from an end of the second filler portion  602   a  to the fourth end  502  is 0 mm-4 mm, the end of the second filler portion  602   a  is towards the first bent region  1132 , and a vertical distance from an end of the second filler portion  602   a  to the first end  401  is 0 mm-4 mm, the end of the second filler portion  602   a  is towards the second bent region  1141 , and a vertical distance from an end of the third filler portion  603   a  to the second end  402  is 0 mm-4 mm, the end of the third filler portion  603   a  is towards the first bent region  1132 . 
     Referring to  FIG. 1  and  FIG. 2 , the second filler  70  includes a fourth filler portion  701   a  and a fifth filler portion  702   a . The fourth filler portion  701   a  is disposed in the fourth bent region  1251 , and the fifth filler portion  702   a  is disposed in the fifth bent region  1261 . Projections of the fourth filler portion  701   a , the fifth filler portion  702   a , the first tab  40 , and the second tab  50  on the electrode assembly  10  do not overlap. 
     In the width direction of the electrode assembly  10 , the vertical distance from an end of the fourth filler portion  701   a  to the third end  501  is 0 mm-4 mm, the end of the fourth filler portion  701   a  is towards the second bent region  1141 , and the vertical distance from an end of the fifth filler portion  702   a  to the second end  402  is 0 mm-4 mm, the end of the fifth filler portion  702   a  is towards the first bent region  1132 . 
     Embodiment 4 
     Embodiment 4 differs from Embodiment 1 in the first filler  60  in Embodiment 4, and differs in that the battery  100  in Embodiment 4 further includes a third filler  80 . 
     Referring to  FIG. 7 , the first filler  60  is disposed in the first planar region  1131  or the second planar region  1142 . 
     The third filler  80  includes a first blank current collector  801  opposite to the first bent region  1132  and a second blank current collector  802  opposite to the first bent region  1132 . The first blank current collector  801  is disposed at an end of the first planar region  1131 , the end of the first planar region  1131  is away from the first bent region  1132 , and is bent against the first planar region  1131 . The second blank current collector  802  is disposed at an end of the first double-surface-coated region  115 , the end of the first double-surface-coated region  115  is away from the first blank region  113 , and is bent against the first double-surface-coated region  115 . Projections of the first blank current collector  801 , the second blank current collector  802 , the first tab  40 , and the second tab  50  in the thickness direction of the electrode assembly  10  do not overlap. 
     In the width direction of the electrode assembly  10 , a vertical distance from an end of the first blank current collector  801  to the second end  402  is 0 mm-4 mm, the end of the first blank current collector  801  is towards the first bent region  1132 , and a vertical distance from an end of the second blank current collector  802  to the second end  402  is 0 mm-4 mm, the end of the second blank current collector  802  is towards the first bent region  1132 . 
     The following describes the electrolytic solution  30  in this application in detail with reference to embodiments. 
     The electrolytic solution  30  includes a lithium salt, an organic ester solvent, and a film-forming additive. The organic ester solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). The film-forming additive includes 1,3-propanesultone (PS), vinylene carbonate (VC), halogenated carbonate (FEC), and lithium difluorophosphate (LiPO 2 F 2 ). 
     Ingredients and content thereof in Comparative Embodiment 1 and Embodiments 1-17 are listed in Table 1, and test conditions and test results of the battery  100  that uses the electrolytic solution  30  prepared in Comparative Embodiment 1 and Embodiments 1-17 are listed in Table 2. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Ingredient of 
                 Molar 
                   
                   
                   
                   
                   
               
               
                 electrolytic 
                 concentration 
                 Organic ester 
               
               
                 solution 30 
                 of lithium salt 
                 solvent 
                 PS 
                 VC 
                 FEC 
                 LiPO 2 F 2   
               
               
                   
               
             
            
               
                 Comparative 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 0% 
                 0% 
                 0% 
               
               
                 Embodiment 1 
               
               
                 Embodiment 1 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0.5%     
                 0% 
                 0% 
                 0% 
               
               
                 Embodiment 2 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 1% 
                 0% 
                 0% 
                 0% 
               
               
                 Embodiment 3 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 0% 
                 0% 
                 0% 
               
               
                 Embodiment 4 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 3% 
                 0% 
                 0% 
                 0% 
               
               
                 Embodiment 5 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 0.5%     
                 0% 
                 0% 
               
               
                 Embodiment 6 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 1% 
                 0% 
                 0% 
               
               
                 Embodiment 7 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 1.5%     
                 0% 
                 0% 
               
               
                 Embodiment 8 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 0% 
                 2% 
                 0% 
               
               
                 Embodiment 9 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 0% 
                 0% 
                 0.5%     
               
               
                 Embodiment 10 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 2% 
                 1% 
                 2% 
                 0.5%     
               
               
                 Embodiment 11 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 1% 
                 1% 
                 2% 
                 0.5%     
               
               
                 Embodiment 12 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0.5%     
                 1% 
                 2% 
                 0.5%     
               
               
                 Embodiment 13 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 1% 
                 2% 
                 0.5%     
               
               
                 Embodiment 14 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 1% 
                 2% 
                 0% 
               
               
                 Embodiment 15 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 1.5%     
                 2% 
                 0% 
               
               
                 Embodiment 16 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 1% 
                 3% 
                 0% 
               
               
                 Embodiment 17 
                 1.0 mol/L 
                 EC/PC/EMC/DEC 
                 0% 
                 1% 
                 2% 
                 1% 
               
               
                   
               
            
           
         
       
     
     The percentages shown in Table 1 are the weight percent of PS, VC, FEC, and LiPO 2 F 2  in the electrolytic solution  30 . In the electrolytic solution  30 , a weight percent of the ethylene carbonate is 5%-23%, a weight percent of the propylene carbonate is 0%-30%, a weight percent of the ethyl methyl carbonate is 0%-60%, and a weight percent of the diethyl carbonate is 0%-60%. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                 Expansion rate 
               
               
                   
                   
                   
                 Expansion rate 
                 of the battery 
               
               
                   
                 Quantity of 
                 Quantity of 
                 of the battery 
                 100 after 3 
               
               
                   
                 cycles of the 
                 cycles of the 
                 100 after 30- 
                 cycles after 
               
               
                   
                 battery 100 
                 battery 100 
                 day storage 
                 30-day storage 
               
               
                 Test condition 
                 under 25° C. 
                 under 45° C. 
                 under 60° C. 
                 under 60° C. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Comparative 
                 101 
                 43 
                 90%  
                 120%  
               
               
                 Embodiment 1 
               
               
                 Embodiment 1 
                 155 
                 89 
                 60%  
                 90%  
               
               
                 Embodiment 2 
                 224 
                 156 
                 30%  
                 35%  
               
               
                 Embodiment 3 
                 287 
                 205 
                 15%  
                 17%  
               
               
                 Embodiment 4 
                 291 
                 218 
                 13%  
                 15%  
               
               
                 Embodiment 5 
                 368 
                 284 
                 10%  
                 11%  
               
               
                 Embodiment 6 
                 509 
                 412 
                 8% 
                 9% 
               
               
                 Embodiment 7 
                 549 
                 467 
                 6% 
                 6% 
               
               
                 Embodiment 8 
                 501 
                 405 
                 8% 
                 9% 
               
               
                 Embodiment 9 
                 489 
                 401 
                 7% 
                 8% 
               
               
                 Embodiment 10 
                 1050 
                 859 
                 4% 
                 4% 
               
               
                 Embodiment 11 
                 998 
                 847 
                 5% 
                 5% 
               
               
                 Embodiment 12 
                 969 
                 825 
                 6% 
                 6% 
               
               
                 Embodiment 13 
                 824 
                 791 
                 7% 
                 7% 
               
               
                 Embodiment 14 
                 678 
                 577 
                 8% 
                 8% 
               
               
                 Embodiment 15 
                 1008 
                 919 
                 5% 
                 5% 
               
               
                 Embodiment 16 
                 980 
                 824 
                 6% 
                 6% 
               
               
                 Embodiment 17 
                 991 
                 851 
                 4% 
                 4% 
               
               
                   
               
            
           
         
       
     
     In Table 2, after a capacity of the battery  100  is reduced to 80%, cycle performance and the expansion rate of the battery  100  are tested under different test conditions. 
     As can be learned from Table 1 and Table 2, the content of PS, VC, FEC, and LiPO 2 F 2  is adjusted in this application. Therefore, the weight percent of PS in the electrolytic solution  30  is effectively controlled to be 0%-1% while excellent cycle performance and high-temperature storage performance of the battery  100  are ensured, thereby reducing hazards of PS to a human body. 
     The foregoing embodiments are merely intended for describing the technical solutions of this application but not intended as a limitation. Although this application is described in detail with reference to the foregoing optional embodiments, a person of ordinary skill in the art understands that modifications or equivalent substitutions may be made to the technical solutions of this application without departing from the spirit and conception of the technical solutions of this application.