LITHIUM-ION BATTERY
`
`CROSS-REFERENCE TO RELATED APPLICATIONS
`
`[0001]
`
`This application is a continuation of US. Patent Application No. 14/810,314,
`
`entitled “LITHIUM-ION BATTERY” filed July 27, 2015, which claimed priority to and
`
`benefits of Chinese Patent Application Serial No. 2014105000741, entitled “LITHIUM-ION
`
`BATTERY” filed with the State Intellectual Property Office of P. R. China on September 25,
`
`2014, all of which are incorporated herein by reference.
`
`TECHNICAL FIELD
`
`[0002]
`
`The present disclosure relates to the field of battery technology, and particularly
`
`relates to a lithium-ion battery.
`
`BACKGROUND
`
`[0003]
`
`Lithium-ion battery has become an ideal power source used in mobile devices for
`
`replacing the conventional power source, due to the advantages of high energy density, high
`
`working voltage, long service life, no memory effect, non—pollution and the like. With the
`
`intellectualization and the multi—functionalization of mobile devices, the power consumption
`
`increases sharply, making a higher requirement to the energy density of lithium—ion battery.
`
`[0004]
`
`Sony has developed lithium-ion battery of graphite type since 1991, and after 20
`
`years of development, the energy density approaches to the limit. While some key problems
`
`for the development of new chemical systems are to be resolved, such as the self-
`
`pulverization brought by the expansion after silicon-based negative active material cycling,
`
`poor high temperature cycling performance of the positive active material at high voltage,
`
`poor stability of electrolyte at high voltage, gas production by the reaction of positive active
`
`material with electrolyte and the like.
`
`[0005]
`
`The promotion of the energy density has run into the bottleneck. To improve user
`
`experience, the development of lithium-ion battery with fast charge at high rate can make up
`
`for the disadvantages of energy density. But when lithium-ion battery is charged quickly at
`
`high rate, the electrode polarization of lithium-ion battery is serious, and the current per unit
`
`area increases, and the negative electrode quickly reaches to the potential of the lithium
`
`precipitation. Plenty of lithium ions diffusing from the positive electrode to the negative
`
`electrode can’t be accepted by the negative in time. The precipitation of lithium on the
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`024607-02-5014-US
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`l
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`

`

`negative electrode surface causes quick fade of the lithium-ion battery capacity. And the
`
`accumulation of lithium dendritic crystal on the electrode surface will impale the separator
`
`easly and pose a big threat to the safety performance of battery.
`
`SUMMARY
`
`[0006]
`
`In view of the problems mentioned in background, the present disclosure aims to
`
`provide a lithium—ion battery, which can be charged quickly at high rate, with excellent safety
`
`performance and cycle performance.
`
`[0007]
`
`In order to achieve above object, the present disclosure provides a lithium-ion
`
`battery, which includes:
`
`a positive electrode including a positive current collector and a positive conductive
`
`membrane which is formed on the surface of the positive current collector by coating, drying
`
`and compacting a positive mixture slurry containing a positive active material, a positive
`
`conductive additive and a positive binder; a negative electrode including a negative current
`
`collector and a negative conductive membrane which is formed on the surface of the negative
`
`current collector by coating, drying and compacting a negative mixture slurry containing a
`
`negative active material, a negative conductive additive and a negative binder; a separator; an
`
`electrolyte; and a packaging foil. The compacted density of the positive conductive
`
`membrane is at a range from 3.9g/cm3 to 4.4g/cm3; the compacted density of negative
`
`conductive membrane is at a range from 1.55g/cm3 to 1.8g/cm3; the ratio of the capacity of
`
`the negative active material to the capacity of the positive active material is at a range from 1
`
`to 1.4, the charging rate of said lithium-ion battery is at a range from 1.3C to SC, in which the
`
`capacity of negative active material / the capacity of positive active material = (negative
`
`coating weight per unit areaX the weight ratio of negative active materials X the capacity per
`
`gram of negative active material)/(positive coating weight per unit area X the weight ratio of
`
`positive active materials X the capacity per gram of positive active material).
`
`[0008]
`
`The benefits of the present disclosure include:
`
`The lithium-ion battery of the present disclosure can be charged quickly at high rate.
`
`[0009]
`
`The lithium-ion battery of the present disclosure has excellent safety performance
`
`and cycle performance.
`
`DETAILED DESCRIPTION OF EMBODIMENTS
`
`[0010]
`
`The lithium—ion battery of the present disclosure is illustrated in details, referring
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`024607-02-5014-US
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`2
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`

`

`to Examples, Comparative Examples and Testing results,
`
`[0011]
`
`First of all, the lithium-ion battery of the present disclosure includes: a positive
`
`electrode including a positive current collector and a positive conductive membrane which is
`
`formed on the surface of the positive current collector by coating, drying and compacting a
`
`positive mixture slurry containing a positive active material, a positive conductive additive
`
`and a positive binder; a negative electrode including a negative current collector and a
`
`negative conductive membrane which is formed on the surface of the negative current
`
`collector by coating, drying and compacting a negative mixture slurry containing a negative
`
`active material, a negative conductive additive and a negative binder; a separator; an
`
`electrolyte, and a packaging foil. The compacted density of the positive conductive
`
`membrane is at a range from 3.9g/cm3 to 4.4g/cm3; the compacted density of negative
`
`conductive membrane is at a range from 1.55g/cm3 to 1.8g/cm3, the ratio of the capacity of
`
`the negative active material to the capacity of the positive active material is at a range from 1
`
`to 1.4.
`
`[0012]
`
`In said lithium—ion battery of the present disclosure, on the one hand the lithium
`
`ion diffusion in negative electrode is accelerated by reducing the negative electrode
`
`polarization, on the other hand the diffusion velocity of lithium ion in positive electrode is
`
`slowed down by increasing the positive electrode polarization. Thus the charging process
`
`transforms quickly from charging with a constant current to charging with a constant voltage.
`
`The electrical current decreases gradually, and the amount of lithium ion diffusing from the
`
`positive electrode to the negative electrode per unit time is decreased. So the formation of
`
`lithium dendrite on the negative electrode surface can be effectively avoided, and the lithium-
`
`ion battery has excellent safety performance and cycle performance.
`
`[0013]
`
`To reduce the negative electrode polarization, (1) at coating process, the ratio
`
`(CB) of the capacity of the negative active material to the capacity of the positive active
`
`material is adjusted as large as possible. Because at the same SOC, if the CB of the all-battery
`
`is smaller, the lithium intercalation of the negative electrode is more sufficient, and the
`
`negative electrode potential is lower. In the charging process, it is shown as that the negative
`
`electrode reaches the precipitation potential of lithium quickly, making the precipitation of
`
`lithium easier. When the CB increases, the negative electrode potential is improved, and the
`
`lithium precipitation on the negative electrode surface can be effectively avoided, and the fast
`
`charging capability of lithium-ion battery at high rate can be improved. Meanwhile a higher
`
`CB easily leads to a lower energy density of lithium—ion battery, so the CB of the present
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`9)
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`

`

`disclosure is at a range from 1 to 1.4, (2) at cold compacting step, the porosity of the negative
`
`conductive membrane can be increased by decreasing the compacted density of negative
`
`conductive membrane. And then the polarization on negative electrode surface is decreased,
`
`making the current distribution more uniform along the thickness direction. More negative
`
`active materials accept Li+ simultaneously in fast charge at high rate to avoid the lithium
`
`precipitation on the negative electrode surface. But a lower compacted density of negative
`
`conductive membrane makes the porosity of negative conductive membrane too high and the
`
`energy density of lithium-ion battery too low. So in the present disclosure, the compacted
`
`density of negative conductive membrane is at a range from 1.55g/cm3 to 1.8g/cm3.
`
`[0014]
`
`To increase the positive electrode polarization, at cold compacting step, increase
`
`in the compacted density of positive conductive membrane and decrease in the channel for
`
`lithium ion diffusion make the charging quickly transform to a constant voltage charging and
`
`the current decrease. Thus the lithium precipitation on the negative electrode sulface can be
`
`effectively avoided. But a too high compacted density of positive conductive membrane
`
`easily leads to the fracture of positive electrode, which is harmful for the safety performance
`
`and cycle performance of lithium—ion battery. So in the present disclosure, the compacted
`
`density of positive conductive membrane is at a range from 3.9g/cm3 to 4.4g/cm3.
`
`[0015]
`
`In said lithium-ion battery of the present disclosure, the compacted density of said
`
`positive conductive membrane is at a range from 3.95g/cm3 to 4.35g/cm3.
`
`[0016]
`
`In said lithium-ion battery of the present disclosure, the compacted density of said
`
`negative conductive membrane is at a range from 1.55g/cm3 to 1.75g/cm3.
`
`[0017]
`
`In said lithium-ion battery of the present disclosure, the ratio (CB) of the capacity
`
`of the negative active material to the capacity of the positive active material is at a range from
`
`1.03 to 1.2.
`
`[0018]
`
`In said lithium—ion battery of the present disclosure, the charging rate of said
`
`lithium-ion battery is at a range from 1.3C to SC.
`
`[0019]
`
`In said lithium-ion battery of the present disclosure, in formation of the negative
`
`conductive membrane, the coating weight of solid components in the negative mixture slurry
`
`on the surface of the negative current collector is at a range from 120mg/154O.25mm2 to
`
`190mg/1540.25mm2, in formation of the positive conductive membrane, the coating weight
`
`of solid components in the positive mixture slurry on the surface of the positive current
`
`collector is at a range from 230mg/1540.25mm2 to 380mg/1540.25mm2. The coating weight
`
`of solid components in conductive membrane can be reduced in the design of lithium—ion
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`024607-02-5014-US
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`4
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`

`

`battery, because when the coating weight of solid components in conductive membrane is
`
`reduced, the current per unit area is decreased, and the concentration polarization along the
`
`thickness direction of electrode is alleviated. Thus the precipitation of lithium on the negative
`
`electrode surface in fast charging can be effectively avoided.
`
`[0020]
`
`In said lithium-ion battery of the present disclosure, said positive active material is
`
`at least one selected from the group consisting of cobalt acid lithium (LiCoOz), manganic
`
`acid lithium (LiMn204), lithium iron phosphate (LiFePO4) and ternary compound (NCM).
`
`Wherein, the ternary compound is at least one selected from the group consisting of the
`
`lithium nickel manganese cobalt oxides.
`
`[0021]
`
`In said lithium-ion battery of the present disclosure, said negative active material
`
`is carbon material which is at least one selected from the group consisting of soft carbon,
`
`hard carbon, artificial graphite, natural graphite and mesocarbon microbead.
`
`[0022]
`
`In said lithium-ion battery of the present disclosure, said separator is at least one
`
`selected from the group consisting of polyethylene (PE) membrane and polypropylene (PP)
`
`membrane. The thickness of said separator is from Sum to 30um.
`
`[0023]
`
`In said lithium—ion battery of the present disclosure, said electrolyte is a non—water
`
`electrolyte containing a non-water organic solvent and a lithium salt.
`
`[0024]
`
`In said lithium-ion battery of the present disclosure, said non-water organic
`
`solvent is a mixture of chain ester and cyclic ester, said chain ester is at least one selected
`
`from the group consisting of dimethyl carbonate DMC, diethyl carbonate DEC, ethyl methyl
`
`carbonate EMC, methyl propyl carbonate MPC, dipropyl carbonate DPC, fluorine-containing
`
`chain ester, sulphur-containing chain ester and unsaturated carbon-carbon bond-containing
`
`chain ester; said cyclic ester is at least one selected from the group consisting of ethylene
`
`carbonate EC, propylene carbonate PC, vinylene carbonate VC, y—butyrolactone y—BL,
`
`trimethylene sulf1te, fluorine—containing cyclic ester, other sulphur—containing cyclic ester and
`
`other unsaturated carbon-carbon bond-containing cyclic ester.
`
`[0025]
`
`In said lithium-ion battery of the present disclosure, said lithium salt is at least one
`
`selected from the group consisting of LiPFs, LiBF4, LiClO4, LiCF3SO3, LiN(SOzCF3)2 and
`
`LiN(SOzC2F5)2. Preferably, the lithium salt is LiPFs.
`
`[0026]
`
`The Examples using the lithium-ion battery and the electrolyte of the present
`
`disclosure are shown below.
`
`[0027]
`
`(1) Preparation of positive electrode
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`024607-02-5014-US
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`5
`
`Example 1
`
`

`

`N—methyl pyrrolidone (NMP) was used as a solvent to dissolve the positive binder
`
`polyvinylidene fluoride (PVDF). And a binder solution with mass fraction of 8% was
`
`obtained. Then LiCoOz (capacity per gram was 160mAh/g) used as a positive active material
`
`and carbon black used as positive conductive additive were added into the binder solution
`
`under stirring. The homogeneous positive mixture slurry was obtained by further stirring. In
`
`the positive mixture slurry, the weight ratio of LiCoOz, PVDF and carbon black was
`
`97: 1.5: 1.5. Then the positive mixture slurry was coated evenly on the aluminum foil used as
`
`the positive current collector and the coating weight was 334mg/1540.25mm2. After drying at
`
`120°C, the positive conductive membrane was obtained. The positive conductive membrane
`
`was cold compacted and adjusted the thickness, making its compacted density become
`
`3.95g/cm3. After being cut, the positive electrode of 72mm>< 1024mm was obtained.
`
`[0028]
`
`(2) Preparation of the negative electrode
`
`Artificial graphite (capacity per gram was 360mAh/g) used as negative active materials,
`
`sodium carboxymethyl cellulose (CMC) used as thickener, styrene butadiene rubber (SBR)
`
`used as positive binder and carbon black used as positive conductive additive were mixed
`
`with the solvent deionized water according to the weight ratio of 96: 1.5: 1.5: 1, and then the
`
`homogeneous negative mixture slurry was obtained by stirring. Then the negative mixture
`
`slurry was coated evenly on the copper foil used as the negative current collector and the
`
`coating weight was 155mg/154O25mm2. After drying at 90°C, the negative conductive
`
`membrane was obtained. Then the negative conductive membrane was cold compacted and
`
`adjusted the thickness, making its compacted density become 1.75g/cm3. After being cut, the
`
`negative electrode of 73.5mmX 1036mm was obtained.
`
`[0029]
`
`(3) Preparation of the electrolyte
`
`In electrolyte, LiPFc was used as lithium salt with the concentration of 1mol/L. A mixture of
`
`ethylene carbonate (EC) and dimethyl carbonate (DMC) (the mass ratio was 1:1) was used as
`
`a non-water organic solvent.
`
`[0030]
`
`(4) Preparation of the lithium-ion battery
`
`The positive electrode, the negative electrode and PE separator with l6um thickness were
`
`coiled to form a square naked-cell. Then the naked-cell was put into aluminum-plastic outer
`
`packing film. After being filled with electrolyte, being sealed and formation, the lithium-ion
`
`battery with a CB of 1.03 was obtained.
`
`Specifically:
`
`CB= the capacity of negative active material / the capacity of positive active material
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`6
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`=(negative coating weight per unit areaX the weight ratio of negative active materials >< the
`
`capacity per gram of negative active material)/(positive coating weight per unit area X the
`
`weight ratio of positive active materials X the capacity per gram of positive active
`
`material).
`
`Example 2
`
`[0031]
`
`The lithium—ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0032]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`314mg/154O.25mm2,
`
`(4) The CB was 1.1.
`
`Example 3
`
`[0033]
`
`The lithium-ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0034]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`288mg/1540.25mm2;
`
`(4) The CB was 1.2.
`
`Example 4
`
`[0035]
`
`The lithium-ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0036]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`265mg/1540.25mm2;
`
`[0037]
`
`(4) The CB was 1.3.
`
`Example 5
`
`[0038]
`
`The lithium-ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0039]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`325mg/1540.25mm2, the compacted density of positive conductive membrane was 4g/cm3,
`
`[0040]
`
`(4) The CB was 1.06.
`
`Example 6
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`024607-02-5014-US
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`7
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`

`[0041]
`
`The lithium-ion battery was prepared using the method same as Example 5, except
`
`the difference as follows:
`
`[0042]
`
`(2) The compacted density of negative conductive membrane was 1.65g/cm3.
`
`Example 7
`
`[0043]
`
`The lithium-ion battery was prepared using the method same as Example 5, except
`
`the difference as follows:
`
`[0044]
`
`(2) The compacted density of negative conductive membrane was 1.55g/cm3.
`
`Example 8
`
`[0045]
`
`The lithium-ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0046]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`3OOmg/1540.25mm2, the compacted density of positive conductive membrane was
`
`3.95 g/cm3;
`
`[0047]
`
`(2) The compacted density of negative conductive membrane was 1.6g/cm3;
`
`[0048]
`
`(4) The CB was 1.15.
`
`Example 9
`
`[0049]
`
`The lithium-ion battery was prepared using the method same as Example 8, except
`
`the difference as follows:
`
`[0050]
`
`(1) The compacted density of positive conductive membrane was 4.1 g/cm3 .
`
`Example 10
`
`[0051]
`
`The lithium-ion battery was prepared using the method same as Example 8, except
`
`the difference as follows:
`
`[0052]
`
`(1) The compacted density of positive conductive membrane was 4.25 g/cm3.
`
`Example 11
`
`[0053]
`
`The lithium-ion battery was prepared using the method same as Example 8, except
`
`the difference as follows:
`
`[0054]
`
`(l) The compacted density of positive conductive membrane was 4.3 5g/cm3.
`
`Example 12
`
`[0055]
`
`The lithium-ion battery was prepared using the method same as Example 1, except
`
`the differences as follows:
`
`[0056]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
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`380mg/154O25mm2, the compacted density of positive conductive membrane was 4.1g/cm3,
`
`[0057]
`
`(2) In formation of the negative conductive membrane, the coating weight of solid
`
`components in negative mixture slurry on the squace of the negative current collector was
`
`185mg/154025mm2, the compacted density of negative conductive membrane was
`
`1.65 g/cm3;
`
`[0058]
`
`(4) The CB was 1.08.
`
`Example 13
`
`[0059]
`
`The lithium-ion battery was prepared using the method same as Example 12,
`
`except the differences as follows:
`
`[0060]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`340mg/154025mm2,
`
`[0061]
`
`(2) In formation of the negative conductive membrane, the coating weight of solid
`
`components in negative mixture slurry on the surface of the negative current collector was
`
`l65mg/154O25mm2.
`
`Example 14
`
`[0062]
`
`The lithium-ion battery was prepared using the method same as Example 12,
`
`except the differences as follows:
`
`[0063]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`290mg/154025mm2,
`
`[0064]
`
`(2) In formation of the negative conductive membrane, the coating weight of solid
`
`components in negative mixture slurry on the surface of the negative current collector was
`
`l4lmg/154O25mm2.
`
`Example 15
`
`[0065]
`
`The lithium-ion battery was prepared using the method same as Example 12,
`
`except the differences as follows:
`
`[0066]
`
`(1) In formation of the positive conductive membrane, the coating weight of solid
`
`components in the positive mixture slurry on the surface of the positive current collector was
`
`250mg/154025mm2,
`
`[0067]
`
`(2) In formation of the negative conductive membrane, the coating weight of solid
`
`components in negative mixture slurry on the surface of the negative current collector was
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`9
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`

`

`l2lmg/1540.25mm2.
`
`[0068]
`
`The testing method and testing results of the lithium-ion batteries provided in the
`
`present disclosure are shown below.
`
`[0069]
`
`(1) Cycle performance test of the lithium-ion battery
`
`At 25°C, the battery was charged with constant current of 2.5C until the voltage reached
`
`4.35V, and then the battery was charged with constant voltage of 4.35V until the current
`
`reached the cut—off current of 0.05C, and then the battery was discharged with constant
`
`current of 1C until the voltage reached the cut-off voltage of 3V, which was a
`
`charge/discharge cycle. The charge/discharge cycle was repeated 350 times.
`
`[007 0]
`
`The capacity retention after 350 cycles (%) = the discharge capacity of the 350th
`
`cycle / the discharge capacity of initial cycle>< 100%.
`
`[0071]
`
`(2) Test for lithium precipitation of negative electrode
`
`At 25°C, the battery was charged with constant current of 2.5C until the voltage reached
`
`4.35V, and then the battery was charged with constant voltage of 4.35V until the current
`
`reached the cut—off current of 0.05C, and then the battery was discharged with constant
`
`current of 1C until the voltage reached the cut—off voltage of 3V, which was a
`
`charge/discharge cycle. The charge/discharge cycle was repeated 10 times. After cycles, the
`
`lithium-ion battery was full charged and took apart, and lithium precipitation on the surface
`
`of negative electrode was observed. Therein, the degree of lithium precipitation was graded
`
`into no lithium precipitation, slight lithium precipitation, medium lithium precipitation and
`
`serious lithium precipitation. No lithium precipitation meant that the area ratio of lithium
`
`precipitation region on the surface of negative electrode was 0%. Slight lithium precipitation
`
`meant that the area ratio of lithium precipitation region on the surface of negative electrode
`
`was less than 20%. Medium lithium precipitation meant that the area ratio of lithium
`
`precipitation region on the surface of negative electrode was at a range from 20% to 70%.
`
`Serious lithium precipitation meant that the area ratio of lithium precipitation region on the
`
`surface of negative electrode was more than 70%. Table 1 showed the parameters and results
`
`of performance test from Example 1 to Example 15.
`
`Table 1 The parameters and results of performance from Example 1 to Example 15
`
`Positive electrode
`
`Negative electrode
`
`Lithium
`
`Capacity
`
`Compacted
`
`.
`.
`Coating weight
`
`compacted
`
`.
`.
`Coating weight
`
`cycles
`
`density
`
`g/cm3
`
`mg/1540.25mm2
`
`density
`
`g/crn3
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`024607-02-5014-US
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`10
`
`mg/1540.25mm2
`
`precipitation
`,
`of negative
`
`retention
`
`after 3 50
`
`electrode
`
`

`

`Example 1
`
`1.03
`
`3.95
`
`334
`
`1.75
`
`155
`
`serious
`
`lithium
`
`50%
`
`70%
`
`82%
`
`93%
`
`precipitation
`medium
`
`
`
`lithium
`
`precipitation
`
`slight lithium
`.
`.
`.
`preClpltatlon
`no lithium
`.
`.
`.
`preClpltatlon
`serious
`
`Example 2
`
`1.1
`
`3 .95
`
`314
`
`Example 3
`
`1.2
`
`3.95
`
`288
`
`1.75
`
`1.75
`
`155
`
`155
`
`Example 4
`
`1.3
`
`Exalnple 5
`
`1.06
`
`265
`
`325
`
`155
`
`155
`
`
`
`lithium
`
`56%
`
`precipitation
`medium
`
`Example 6
`
`1.06
`
`4
`
`325
`
`1.65
`
`155
`
`lithium
`
`72%
`
`Example 7
`
`1.06
`
`4
`
`325
`
`300
`
`1.55
`
`1.6
`
`155
`
`155
`
`slight lithium
`.
`.
`.
`preClpltatlon
`medium
`
`83%
`
`lithillm
`
`73%
`
`precipitation
`
`
`
`Example 8
`
`1.15
`
`3.95
`
`Example 9
`
`1.15
`
`4.1
`
`Example 10
`
`1.15
`
`4.25
`
`Example 11
`
`1.15
`
`4.35
`
`Example 12
`
`1.08
`
`4.1
`
`300
`
`300
`
`300
`
`380
`
`1.6
`
`1.6
`
`1.6
`
`1.65
`
`155
`
`155
`
`155
`
`185
`
`Example 13
`
`1.08
`
`4.1
`
`340
`
`1.65
`
`165
`
`Example 14
`
`1.08
`
`4.1
`
`290
`
`1.65
`
`141
`
`
`
`precipitation
`
`slight lithium
`'
`'
`'
`prCClpltatlon
`no lithium
`.
`.
`.
`preClpltatlon
`no lithium
`'
`'
`'
`preClpltatlon
`serious
`
`lithillm
`
`precipitation
`medium
`
`
`
`lithium
`
`precipitation
`
`slight lithium
`'
`'
`'
`preClpltatlon
`no lithium
`
`84%
`
`93%
`
`96%
`
`55%
`
`71%
`
`84%
`
`95%
`121
`1.65
`250
`4.1
`1.08
`Example 15
`
`precipitation
`
`[0072]
`
`By the contrast from Example 1 to Example 4, it was observed that the lithium
`
`precipitation on the surface of negative electrode was improved significantly and the capacity
`
`retention of the lithium-ion battery increased after 350 cycles, with the decrease of the
`
`coating weight of solid components in the positive conductive membrane and the increase of
`
`024607-02-5014-US
`
`11
`
`

`

`the CB. When the CB was too small, the capacity retention after 350 cycles was low.
`
`[0073]
`
`By the contrast from Example 5 to Example 7, it was observed that the lithium
`
`precipitation on the surface of negative electrode was improved significantly and the capacity
`
`retention of the lithium-ion battery increased after 350 cycles, with the decrease of the
`
`compacted density of negative conductive membrane. When the compacted density of
`
`negative conductive membrane was too high, the capacity retention after 350 cycles was low.
`
`[007 4]
`
`By the contrast from example 8 to example 11, it was observed that the lithium
`
`precipitation on the surface of negative electrode was improved significantly and the capacity
`
`retention of the lithium-ion battery increased after 350 cycles, with the increase of the
`
`compacted density of positive conductive membrane. When the compacted density of
`
`positive conductive membrane was too small, the capacity retention after 350 cycles was low.
`
`[0075]
`
`By the contrast from example 12 to example 15, it was observed that the lithium
`
`precipitation on the surface of negative electrode was improved significantly and the capacity
`
`retention of the lithium-ion battery increased after 350 cycles, with the simultaneous decrease
`
`of the coating weights of solid components in the positive conductive membrane and in the
`
`negative conductive membrane. When the coating weights of solid components in the
`
`positive conductive membrane and in the negative conductive membrane were too high, the
`
`capacity retention after 350 cycles was low.
`
`024607-02-5014-US
`
`12
`
`