Electrolyte blends for lowering resistance and enhancing cycle life

Abstract

Electrolyte blends for lowering resistance and enhancing charge-discharge cycle life in lithium-ion batteries (LiB) containing silicon include a lithium additive in a solvent. The solvent may include diethyl carbonate (DEC) and / or lithium difluorooxalatoborate (LiDFOB).

Description

ELECTROLYTE BLENDS FOR LOWERING RESISTANCE AND ENHANCING CYCLE LIFECROSS-REFERENCE WITH RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 710,141 filed October 22, 2024, entitled “Electrolyte Blends For Lowering Resistance And Enhancing Cycle Life,” the disclosure of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to electrolyte blends. More particularly, the disclosure is related to electrolyte blends for lowering resistance and enhancing chargedischarge cycle life in lithium-ion batteries (LiB) containing silicon.BACKGROUND

[0003] Electrolytes play a crucial role in the performance of LiB from lithium transport across the cell (resistance), solid electrolyte interface (SEI) formation, stability, flexibility and self-healing characteristics. Electrolytes also need to be chemically stable in a range of temperatures and at different potentials, resistant to positive and negatively charged materials, and not corrode such materials. Viscosity control is also an important feature affecting the electrolyte’s ability to fully wet the cell and to maintain mobility of the Li ions.BRIEF DESCRIPTION OF DRAWINGS

[0004] Embodiments of the subject matter are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The subject matter is not limited in its application to the details of construction or the arrangement of the components illustrated in the drawings. Like reference numerals are used to indicate like components, unless otherwise indicated.

[0005] FIG. 1 is a graph depicting cycle life data of the examples.

[0006] FIG. 2 is a graph depicting cycle life data of the examples.

[0007] FIG. 3 is a graph depicting resistance data of the examples.

[0008] FIG. 4 is a graph depicting resistance data of the examples.

[0009] FIG. 5 is a graph depicting cycle life data of the examples.

[0010] FIG. 6 is a graph depicting cycle life data of the examples.

[0011] FIG. 7 is a graph depicting resistance data of the examples.

[0012] FIG. 8 is a graph depicting resistance data of the examples.DETAILED DESCRIPTION

[0013] The following descriptions are provided to explain and illustrate embodiments of the present disclosure. The described examples and embodiments should not be construed to limit the present disclosure.

[0014] Novel advanced silicon anode material has been developed that has the ability to significantly increase the capacity of LiB, enabling smaller energy storage devices in electrical goods, increase the power of these goods or increase the charge life of these materials so devices last longer between each charge. Cell design is critical to fully unlock the potential of advanced silicon anode materials. The present disclosure is related to electrolytes that provide surprising advantages in silicon containing LiB.

[0015] According to embodiments of the present disclosure, the LiB includes an anode comprising silicon. Suitable anode compositions include silicon materials disclosed in U.S. Patent No. 11,069,885 and WO 2023 / 034947 Al, the disclosures of which are hereby incorporated by reference in their entireties. In some embodiments, the anode comprises a porous fiber formed of silicon and carbon. The anode may further include a carbon material such as graphite, carbon nanotubes (CNT), graphene, activated carbon, and the like.

[0016] In some embodiments, the anode comprises silicon in an amount of at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 45 wt%, at least 50 wt%, at least 55 wt%, at least 60 wt%, at least 70 wt%, 5 to 70 wt%, 10 to 65 wt%, 10 to 60 wt%, 20 to 60 wt%, 20 to 50 wt%, 25 to 65 wt%, 25 to 55 wt%, or 30 to 60 wt%.

[0017] The cathode composition is not particularly limited and may, for example, include a metal oxide or mixed metal oxide.

[0018] Additional components and configurations of the batteries disclosed herein are not particularly limited. For example, those of ordinary skill in the art would understand and readily be able to employ various separators, current collectors, leads, housings, wirings, andthe like as well as various battery constructions, such as coin cells, pouch cells, jelly rolls, stacked batteries, and the like.

[0019] In some embodiments, the electrolyte blend includes a lithium additive dissolved in a solvent. In some embodiments, the lithium additive is lithium hexafluorophosphate (LiPFe), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or combinations thereof. In some embodiments, the additive is only LiPFe. In some embodiments, the additive comprises at least 50% LiPFe by mass based on a total mass of the additives. In some embodiments, the additive comprises LiPFe and LiFSI. In some embodiments, the additive may include additional non-lithium-containing components, such as tris(trimethylsilyl) phosphite (TMSP), tris(trimethylsilyl) borate (TMSB), vinyl ethylene carbonate (VEC), or combinations thereof. In some embodiments, the additive consists of or consists essentially of the components and amounts shown in Table 1.

[0020] In some embodiments, the solvent includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), lithium difluorooxalatoborate (LiDFOB), or combinations thereof. In some embodiments, based on a total weight of the solvent or a total weight of the electrolyte, the solvent comprises 15-35 wt% or 20-30 wt% of EC, 40-70 wt% or 44-66 wt% of EMC and / or DMC, 5-25 wt% or 10-20 wt% FEC, and 2-6 wt% VC, PS, and / or LiDFOB. In some embodiments, the solvent comprises only one of EMC or DMC. In some embodiments, the solvent comprises at least two of VC, PS, or LiDFOB. In some embodiments, the solvent comprises at least one of DEC or LiDFOB. In some embodiments, the solvent consists of or consists essentially of the components and amounts shown in Table 1.EXAMPLES

[0021] Coin cells were prepared with a silicon and graphite composite anode having a capacity of 1,000 mAh / g, an NMC622 (LiNio6Mno.2Coo.2O2) cathode, and electrolyte compositions as shown in Table 1 below.TABLE 1Additive SolventSampleLiPFe LiFSI EC EMC DEC FEC VC PS LiDFOB 0 1 0 30 56 0 10 2 2 0 8 1 0 20 0 60 20 0 0 0 8a 1 0 20 0 58 20 0 0 2 8b 1 0 20 0 54 20 2 2 2 8c 1 0 30 0 50 20 0 0 0 8d 1 0 30 0 60 10 0 0 0 8e 1 0 30 0 54 10 2 2 2 10 0.7 0.3 30 56 0 10 2 0 2 10a 0.7 0.3 30 46 0 20 2 0 2 10b 0.7 0.3 30 54 0 10 2 2 2 10c 0.7 0.3 30 44 0 20 2 2 2 lOd 0.7 0.3 20 66 0 10 2 0 2 10c 0.7 0.3 20 56 0 20 2 0 2

[0022] In Table 1, the values for lithium hexafluorophosphate (LiPFe) and lithium bis(fluorosulfonyl)imide (LiFSI) are shown as molar concentrations in the solvent. The solvent materials, ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), and lithium difluorooxalatoborate (LiDFOB), are shown in weight percentage.

[0023] The coin cells were cycled at 25 °C between 3.0 V and 4.15 V at a cycling rate of 25C / 0.5C. FIG. 1 and FIG. 2 demonstrate capacity retention (%) and coulombic efficiency (%) of reference Sample 0 and Samples 8-8e. FIG. 3 and FIG. 4 demonstrate resistance values for reference Sample 0 and Samples 8a-8d. FIG. 5 and FIG. 6 demonstrate capacity retention (%) and coulombic efficiency (%) of reference Sample 0 and Samples 10-10e. FIG. 7 and FIG. 8 demonstrate resistance values for reference Sample 0 and Samples 10-10e.

[0024] Reference Sample 0 provided poor capacity retention and coulombic efficiency as compared with Samples 8-8e and 10-10e.

[0025] Although the present disclosure has been described using certain embodiments and optional features, modification and variation of the embodiments herein disclosed can beforeseen by those of ordinary skill in the art, and such modifications and variations are considered to be within the scope of the present disclosure. It is also to be understood that the above description is intended to be illustrative and not restrictive. For instance, it is noted that the weight percentage values described above are illustrative only and can be readily adjusted by one of ordinary skill in the art to fit a wide range of potential electrolyte compositions, batteries and processes. Many alternative embodiments will be apparent to those of ordinary skill in the art upon reviewing the above description. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the future shown and described or any portion thereof, and it is recognized that various modifications are possible within the scope of the disclosure.

Claims

CLAIMSWhat is claimed is:

1. A lithium-ion battery comprising:an anode comprising silicon;a cathode; andan electrolyte comprising an additive comprising lithium in a solvent comprising a carbonate.

2. The lithium-ion battery of claim 1, wherein the solvent comprises diethyl carbonate (DEC) and / or lithium difluorooxalatoborate (LiDFOB).

3. The lithium ion battery of claim 1, wherein the anode comprises silicon in an amount of at least 5 wt%.

4. The lithium ion battery of claim 3, wherein the anode comprises silicon in an amount of 5 to 70 wt%.

5. The lithium ion battery of claim 1, wherein the electrolyte comprises a lithium additive is selected from lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and combinations thereof.

6. The lithium ion battery of claim 1, wherein the solvent is selected from ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sultone (PS), lithium difluorooxalatoborate (LiDFOB), and combinations thereof.

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