Anode electrode having anode active material layer comprising lithium silicon oxide or silicon oxide and styrene butadiene rubber

Abstract

The invention provides an anode electrode. The anode electrode comprises an anode current collector. The anode active material layer includes an anode active material including lithium silicon oxide, silicon oxide, lithium silicon oxide, and graphite, and at least one of silicon oxide and graphite. The anode active material layer further comprises a binder comprising a mixture of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (NaCMC), and sodium polyacrylate (NaPAA), where the SBR accounts for more than 60% by weight of the binder.

Description

Technical Field

[0001] The present disclosure relates to battery cells, and more particularly to anode electrodes comprising lithium silicon oxide for battery cells. Background Art

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that work currently named as inventors is described in this section, and aspects of the specification that may not have been otherwise identified as prior art at the time of filing, are not admitted, either explicitly or implicitly, as prior art to the present disclosure.

[0003] The present disclosure relates to battery cells, and more particularly to anode electrodes comprising lithium silicon oxide for battery cells.

[0004] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, include one or more motors and a battery system including one or more battery cells, modules, and / or battery packs. A battery control module is used to control the charging and / or discharging of the battery system during charging and / or driving. EV manufacturers are seeking increased power density to increase the range of EVs. Summary of the invention

[0005] The anode electrode includes an anode current collector. The anode active material layer includes an anode active material, and the anode active material includes at least one of lithium silicon oxide, silicon oxide, lithium silicon oxide and graphite, and silicon oxide and graphite. The anode active material layer also includes a binder, and the binder includes a mixture of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylate (NaPAA), wherein SBR accounts for more than 60% by weight of the binder.

[0006] In other features, the anode active material layer further comprises a conductive filler. The conductive filler comprises first particles having an aspect ratio of less than 2 and second particles having an aspect ratio of greater than 20. The first particles account for 0.1 wt % to 3 wt % of the anode active material layer. The first particles account for 0.2 wt % to 1 wt % of the anode active material layer.

[0007] In other features, the first particles are selected from carbon black (CB) and acetylene black. The second particles are selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes, and single-walled carbon nanotubes. The second particles account for 0.05 wt % to 2 wt % of the anode active material layer.

[0008] In other features, the anode active material comprises at least one of lithium silicon oxide and silicon oxide, and wherein at least one of lithium silicon oxide and silicon oxide accounts for more than 18 weight percent of the anode active material layer. The anode active material accounts for 83 weight percent to 97 weight percent of the anode active material layer. The anode active material accounts for 93 weight percent to 96 weight percent of the anode active material layer.

[0009] In other features, SBR accounts for 1% to 6% by weight of the anode active material layer. SBR accounts for 1.2% to 3% by weight of the anode active material layer. NaCMC accounts for 0.2% to 2% by weight of the anode active material layer. NaCMC accounts for 0.3% to 1% by weight of the anode active material layer. NaPAA accounts for 0.2% to 4% by weight of the anode active material layer.

[0010] The battery cell includes C cathode electrodes, A anode electrodes, S separators, and a battery cell housing, wherein C, A, and S are integers greater than 1. The C cathode electrodes, A anode electrodes, and S separators are arranged in a predetermined order in the battery cell housing.

[0011] The anode electrode includes an anode current collector. The anode active material layer includes an anode active material, and the anode active material includes at least one of lithium silicon oxide, silicon oxide, lithium silicon oxide and graphite, and silicon oxide and graphite. The anode active material layer includes a binder, and the binder includes a mixture of styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (NaCMC). SBR accounts for more than 60% by weight of the binder. The conductive filler includes a first particle with an aspect ratio of less than 2 and a second particle with an aspect ratio of greater than 20.

[0012] In other features, the first particles account for 0.1 wt % to 3 wt % of the anode active material layer, the first particles are selected from carbon black (CB) and acetylene black, the second particles account for 0.05 wt % to 2 wt % of the anode active material layer, and the second particles are selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes and single-walled carbon nanotubes.

[0013] In other features, the anode active material comprises 83 wt % to 97 wt % of the anode active material layer, SBR comprises 1 wt % to 6 wt % of the anode active material layer, and NaCMC comprises 0.2 wt % to 2 wt % of the anode active material layer.

[0014] In other features, the anode active material comprises at least one of lithium silicon oxide and silicon oxide. The at least one of lithium silicon oxide and silicon oxide comprises greater than 18 weight percent of the anode active material layer.

[0015] The present invention provides the following solutions:

[0016] Solution 1. An anode electrode, comprising:

[0017] an anode current collector; and

[0018] An anode active material layer comprising:

[0019] An anode active material comprising a material selected from the group consisting of:

[0020] Lithium silicon oxide;

[0021] Silicon oxide;

[0022] Lithium silicon oxide and graphite; and

[0023] Silicon oxide and graphite; and

[0024] An adhesive comprising a mixture of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylate (NaPAA), wherein SBR accounts for more than 60% by weight of the adhesive.

[0025] Option 2. The anode electrode according to Option 1, wherein the anode active material layer further comprises a conductive filler.

[0026] Option 3. An anode electrode according to Option 2, wherein the conductive filler comprises first particles having an aspect ratio less than 2 and second particles having an aspect ratio greater than 20.

[0027] Option 4. The anode electrode according to Option 3, wherein the first particles account for 0.1 wt % to 3 wt % of the anode active material layer.

[0028] Embodiment 5. The anode electrode according to Embodiment 3, wherein the first particles account for 0.2 wt % to 1 wt % of the anode active material layer.

[0029] Option 6. The anode electrode according to Option 3, wherein:

[0030] The first particles are selected from carbon black (CB) and acetylene black, and

[0031] The second particles are selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes and single-walled carbon nanotubes.

[0032] Embodiment 7. The anode electrode according to Embodiment 3, wherein the second particles account for 0.05 wt % to 2 wt % of the anode active material layer.

[0033] Option 8. An anode electrode according to Option 1, wherein the anode active material comprises at least one of the lithium silicon oxide and the silicon oxide, and wherein the at least one of the lithium silicon oxide and the silicon oxide accounts for greater than 18 weight % of the anode active material layer.

[0034] Option 9. The anode electrode according to Option 1, wherein the anode active material accounts for 83 wt % to 97 wt % of the anode active material layer.

[0035] Embodiment 10. The anode electrode according to Embodiment 1, wherein the anode active material accounts for 93 wt % to 96 wt % of the anode active material layer.

[0036] Embodiment 11. The anode electrode according to Embodiment 1, wherein the SBR accounts for 1 wt % to 6 wt % of the anode active material layer.

[0037] Embodiment 12. The anode electrode according to Embodiment 1, wherein the SBR accounts for 1.2 wt % to 3 wt % of the anode active material layer.

[0038] Embodiment 13. The anode electrode according to Embodiment 1, wherein the NaCMC accounts for 0.2 wt % to 2 wt % of the anode active material layer.

[0039] Embodiment 14. The anode electrode according to Embodiment 1, wherein the NaCMC accounts for 0.3 wt % to 1 wt % of the anode active material layer.

[0040] Embodiment 15. The anode electrode according to Embodiment 1, wherein the NaPAA accounts for 0.2 wt % to 4 wt % of the anode active material layer.

[0041] Solution 16. A battery cell comprising:

[0042] C cathode electrodes;

[0043] A anode electrode according to Scheme 1;

[0044] S spacers; and

[0045] Battery pack battery housing,

[0046] Where C, A and S are integers greater than 1, and

[0047] The C cathode electrodes, the A anode electrodes and the S separators are arranged in a predetermined order in the battery cell housing.

[0048] Solution 17. An anode electrode, comprising:

[0049] Anode current collector;

[0050] An anode active material layer comprising:

[0051] An anode active material comprising a material selected from the group consisting of:

[0052] Lithium silicon oxide;

[0053] Silicon oxide;

[0054] Lithium silicon oxide and graphite; and

[0055] Silicon oxide and graphite;

[0056] An adhesive comprising a mixture of styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (NaCMC), wherein the SBR comprises greater than 60% by weight of the adhesive; and

[0057] The conductive filler comprises first particles with an aspect ratio less than 2 and second particles with an aspect ratio greater than 20.

[0058] Option 18. The anode electrode according to Option 17, wherein:

[0059] The first particles account for 0.1 wt % to 3 wt % of the anode active material layer.

[0060] The first particles are selected from carbon black (CB) and acetylene black,

[0061] The second particles account for 0.05 wt % to 2 wt % of the anode active material layer, and

[0062] The second particles are selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes and single-walled carbon nanotubes.

[0063] Option 19. The anode electrode according to Option 17, wherein:

[0064] The anode active material accounts for 83 wt % to 97 wt % of the anode active material layer;

[0065] The SBR accounts for 1 wt % to 6 wt % of the anode active material layer; and

[0066] The NaCMC accounts for 0.2 wt % to 2 wt % of the anode active material layer.

[0067] Option 20. An anode electrode according to Option 17, wherein the anode active material comprises at least one of the lithium silicon oxide and the silicon oxide, and wherein the at least one of the lithium silicon oxide and the silicon oxide accounts for greater than 18 weight % of the anode active material layer.

[0068] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present disclosure will be more fully understood through the detailed description and accompanying drawings, in which:

[0070] Figure 1 is a side cross-sectional view of an example of a battery cell including an anode electrode, a cathode electrode, and a separator according to the present disclosure;

[0071] Figure 2 The expansion of silicon particles during a first lithiation event and the shrinkage and expansion during subsequent delithiation and relithiation events are illustrated, respectively;

[0072] Figure 3 is a graph illustrating capacity retention as a function of cycle number for battery cells including anode electrodes having different SBR and NaCMC concentrations according to the present disclosure;

[0073] Figure 4 is a graph illustrating capacity retention as a function of cycle number for battery cells including anode electrodes having different SBR, NaCMC, and NaPAA concentrations according to the present disclosure;

[0074] Figure 5 is a graph illustrating the peel strength of anode electrodes having different SBR, NaCMC and / or NaPAA concentrations according to the present disclosure;

[0075] Figure 6 is a graph illustrating the viscosity of adhesives having different degree of substitution (DS) values ​​according to the present disclosure as a function of shear rate;

[0076] Figure 7 is a graph illustrating ionic resistance of battery cells including anode electrodes having different SBR, NaCMC, and / or NaPAA concentrations according to the present disclosure; and

[0077] Figure 8 is a graph illustrating capacity retention as a function of cycle number for battery cells including anode electrodes having different SBR, NaCMC, and / or NaPAA concentrations according to the present disclosure.

[0078] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0079] Although battery cells and anode electrodes according to the present disclosure are described in the context of electric vehicles, the battery cells and anode electrodes may be used in stationary applications and / or other types of applications.

[0080] The battery cell comprises an anode electrode, a cathode electrode and a separator arranged in a predetermined order in a housing. The anode electrode comprises an anode current collector and an anode active material layer arranged on one or both sides of the anode current collector. The anode active material layer comprises an anode active material, one or more binders, and / or one or more conductive fillers. The cathode electrode comprises a cathode current collector and a cathode active material layer arranged on one or both sides of the cathode current collector. The cathode active material layer comprises a cathode active material, one or more binders, one or more additives and / or one or more conductive fillers. The separator is arranged between the anode electrode and the cathode electrode.

[0081] As will be further described below, the anode active material layer of the anode electrode according to the present disclosure includes a combination of (one or more) active materials, (one or more) binders, and (one or more) conductive fillers that optimize the processability and mechanical and electrochemical properties of the anode electrode. In some examples, the anode active material comprises lithium silicon oxide (LiSiO x ), silicon oxide (SiO x ), lithium silicon oxide and graphite, and / or silicon oxide and graphite. In some examples, the silicon oxide includes silicon monoxide, silicon dioxide, or silicon oxide in which the stoichiometric ratio of x is between 1 and 2.

[0082] In some examples, the anode active material accounts for 83 wt % to 97 wt % of the anode active material layer. In some examples, the anode active material accounts for 93 wt % to 96 wt % of the anode active material layer. In some examples, LiSiO x or SiO x At least 18 wt% of the anode active material layer (when LiSiO x or SiO x When used alone or blended with graphite or other materials).

[0083] In the anode active material layer according to the present disclosure, the binder includes styrene-butadiene rubber (SBR) and / or other binder materials. In some instances, SBR accounts for more than 60 weight % of the binder. In some instances, SBR accounts for 1 weight % to 6 weight % of the anode active material layer. In some instances, SBR accounts for 1.2 weight % to 3 weight % of the anode active material layer.

[0084] In some examples, other binder materials include at least one of sodium carboxymethylcellulose (NaCMC) and sodium polyacrylate (NaPAA) to improve the mechanical and electrochemical properties of the battery cell. In some examples, NaCMC accounts for 0.2 wt % to 2 wt % of the anode active material layer. In some examples, NaCMC accounts for 0.3 wt % to 1 wt % of the anode active material layer. In some examples, NaPAA accounts for 0.2 wt % to 4 wt % of the anode active material layer. In some examples, NaPAA accounts for 0.2 wt % to 2 wt % of the anode active material layer.

[0085] In some instances, the anode active material and the binder are combined with one or more conductive fillers. In some instances, the one or more conductive fillers include first particles and second particles. In some instances, the first particles include one or more materials selected from carbon black (CB) and / or acetylene black. In some instances, the second particles include one or more materials selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes and / or single-walled carbon nanotubes.

[0086] In some examples, the aspect ratio of the first particles is less than 2 (e.g., ˜1), and the aspect ratio of the second particles is greater than or equal to 20 (e.g., 30, 40, 60, etc.). In some examples, the first particles account for 0.1 to 3 weight percent of the anode active material layer. In some examples, the first particles account for 0.2 to 1 weight percent of the anode active material layer. In some examples, the second particles account for 0.05 to 2 weight percent of the anode active material layer.

[0087] Reference now Figure 1 , the battery cell 10 includes A anode electrodes, C cathode electrodes, and S separators, where A, C, and S are integers greater than 1. The battery cell 10 includes C cathode electrodes 20-1, 20-2, ..., and 20-C. The C cathode electrodes 20 include a cathode active material layer 24 arranged on one side or both sides of a cathode current collector 26. The battery cell 10 includes A anode electrodes 40-1, 40-2, ..., and 40-A. The A anode electrode 40 includes an anode active material layer 42 arranged on one side or both sides of an anode current collector 46. The C cathode electrodes 20, the A anode electrodes 40, and the S separators 32 are arranged in a predetermined order in the housing 50. For example, the S separators 32 are arranged between the C cathode electrodes 20 and the A anode electrodes 40.

[0088] Reference now Figure 2, the anode active material includes silicon particles that expand and contract during cycling. During the first lithiation event, the silicon particle 60 expands to up to 3 times its original diameter, as shown at 62 (lithiated silicon particle). For subsequent delithiation (at 64) and relithiation (at 62) events, the particle contracts and expands between 2 and 3 times the diameter of the silicon particle 60, respectively. The expansion and / or contraction induces stress in the active material layer of the anode electrode.

[0089] Reference now Figure 3 and Figure 4 , for anode electrodes containing different concentrations of SBR, NaCMC and / or NaPAA, the capacity retention is shown as a function of cycle number. Figure 3 The test samples included SBR and NaCMC. The first sample contained 1.3 wt% NaCMC and 2.6 wt% SBR. The second sample contained 1.6 wt% NaCMC and 2.3 wt% SBR. The third sample contained 1.95 wt% NaCMC and 1.95 wt% SBR. The anode active material layer in the sample contained 57 wt% graphite, 38 wt% LiSiO x , 3.9 wt% binder, 1 wt% CB, and 0.1 wt% SW-CNT. In this example, all samples contained 3.9 wt% binder, but other binder concentrations can also be used. Figure 3 It can be seen that the capacity retention rate increases with the increase of SBR concentration.

[0090] exist Figure 4 In the examples, the binder contained different concentrations of SBR, NaCMC and / or NaPAA. In this example, all samples contained 3.9 wt% binder, but other binder concentrations can also be used. The first sample contained 0.6 wt% NaPAA, 0.6 wt% NaCMC and 2.7 wt% SBR. The second sample contained 1.35 wt% NaPAA, 0.6 wt% NaCMC and 1.95 wt% SBR. The third sample contained 1.95 wt% NaPAA, 0.6 wt% NaCMC and 1.35 wt% SBR. The fourth sample contained 2.7 wt% NaPAA, 0.6 wt% NaCMC and 0.6 wt% SBR. Figure 4 It can be seen that the capacity retention rate increases with the increase of SBR concentration.

[0091] Reference now Figure 5 , showing the peel strength of anode electrodes containing different SBR, NaCMC and / or NaPAA concentrations. SBR improves the adhesion strength of the anode current collector and / or the cohesion between particles. In some examples, SBR is used in combination with NaCMC or both NaCMC and NaPAA. Figure 5In the example in , all the anode active material layers contain 3.9 wt % of binder in the anode active material layer. Generally, a peel strength greater than 20 N / m is considered sufficient for roll-to-roll production. Figure 5 It can be seen that samples containing 1.95 wt % SBR with both NaCMC and NaPAA, 2.3 wt % SBR with NaCMC (or NaCMC and NaPAA (not shown)), or 1.95 wt % SBR with NaCMC or both NaCMC and NaPAA have peel strength sufficient for roll-to-roll production.

[0092] Reference now Figure 6 The viscosity (in Pascal-seconds (Pa-s)) is shown as a function of shear rate for NaCMC with different degrees of substitution (DS). 2 3 wt% of acetylene black and polymer (e.g., 0.75 wt%) per gram of surface area were mixed. NaCMC with low DS was the most effective carbon dispersant. Samples included NaCMC with DS=0.7, DS=0.9, and DS=1.2.

[0093] Lower viscosity corresponds to higher carbon dispersion, thereby avoiding carbon agglomeration. Due to the combination of hydrophobic and hydrophilic segments of carboxymethyl cellulose (CMC), CMC is a good dispersant of hydrophobic carbon in water. This effect is amplified when the degree of substitution (DS) is lower when the polymer has more hydrophobic segments. In some instances, the DS of NaCMC is less than or equal to 1.0. In some instances, the DS of NaCMC is less than or equal to 0.8.

[0094] Reference now Figure 7 and Figure 8 , shows the ionic resistance of the anode electrode with different SBR, NaCMC and / or NaPAA concentrations. Increasing the SBR concentration increases the ionic resistance, as Figure 7 As shown in Figure 8 , the charge retention of battery cells containing different concentrations of SBR, NaCMC and / or NaPAA is shown. Replacing part of NaCMC with NaPAA reduces the ionic resistance and improves the rate capability without significantly affecting the cycle life.

[0095] The foregoing description is essentially only exemplary and is absolutely not intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be limited thereto, because after studying the drawings, the specification and the following claims, other modifications will become apparent. It should be understood that one or more steps in the method may be implemented in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more features described with respect to any embodiment of the present disclosure may be implemented in any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and the mutual replacement of one or more embodiments is still within the scope of the present disclosure.

[0096] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "on," "under," and "disposed." Unless explicitly described as "directly," when describing the relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship in which no other intervening elements exist between the first element and the second element, or an indirect relationship in which one or more intervening elements exist between the first element and the second element (spatially or functionally). The phrase "at least one of A, B, and C" as used herein should be interpreted to mean a logical (A or B or C) using a non-exclusive logical OR, and should not be interpreted to mean "at least one A, at least one B, and at least one C."

[0097] In the drawings, the direction of the arrows, as shown by arrows, generally demonstrates the flow of information (such as data or instructions) related to the diagram. For example, when component A and component B exchange various information but the information transmitted from component A to component B is related to the diagram, the arrow may point from component A to component B. Such a unidirectional arrow does not mean that no other information is transmitted from component B to component A. In addition, for the information transmitted from component A to component B, component B may send a request for the information to component A or a receipt of the information.

Claims

1. An anode electrode, comprising: Anode current collector; and An anode active material layer comprising: An anode active material comprising a material selected from the group consisting of: Lithium silicon oxide; Silicon oxide; Lithium silicon oxide and graphite; and Silicon oxide and graphite; and An adhesive comprising a mixture of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylate (NaPAA), wherein SBR accounts for more than 60% by weight of the adhesive. 2 . The anode electrode according to claim 1 , wherein the anode active material layer further comprises a conductive filler. 3 . The anode electrode according to claim 2 , wherein the conductive filler comprises first particles having an aspect ratio of less than 2 and second particles having an aspect ratio of greater than 20. 4 . The anode electrode according to claim 3 , wherein the first particles account for 0.1 wt % to 3 wt % of the anode active material layer. 5 . The anode electrode according to claim 3 , wherein the first particles account for 0.2 wt % to 1 wt % of the anode active material layer.

6. The anode electrode according to claim 3, wherein: The first particles are selected from carbon black (CB) and acetylene black, and The second particles are selected from graphene nanosheets, carbon nanofibers, multi-walled carbon nanotubes and single-walled carbon nanotubes. 7 . The anode electrode according to claim 3 , wherein the second particles account for 0.05 wt % to 2 wt % of the anode active material layer.

8. The anode electrode of claim 1, wherein the anode active material comprises at least one of the lithium silicon oxide and the silicon oxide, and wherein the at least one of the lithium silicon oxide and the silicon oxide accounts for greater than 18 wt% of the anode active material layer. 9 . The anode electrode according to claim 1 , wherein the anode active material accounts for 83 wt % to 97 wt % of the anode active material layer. 10 . The anode electrode according to claim 1 , wherein the anode active material accounts for 93 wt % to 96 wt % of the anode active material layer.

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