ELECTROLYTE COMPOSITION, AND BATTERY AND DEVICE WITH THE ELECTROLYTE COMPOSITION

Abstract

An electrolyte composition for batteries is provided. The electrolyte composition comprises a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, a lithium salt derivative thereof, or a combination thereof. Additionally, a battery and a device containing the electrolyte composition are provided.

Description

INTRODUCTION

[0001] The disclosure relates generally to an electrolyte composition for batteries.

[0002] Battery cells can contain an anode, a cathode, an electrolyte mixture, and a separator. A battery cell can operate in charging mode, absorbing electrical energy. A battery cell can also operate in discharging mode, releasing electrical energy. A battery cell can undergo charge and discharge cycles, in which the battery first absorbs and stores electrical energy and then releases electrical energy to a connected system. In vehicles that use electrical energy to generate propulsion, the vehicle's battery cells can be charged, and the vehicle can then drive for a period of time, using the stored electrical energy to generate propulsion.

[0003] A battery cell contains an electrolyte composition that provides lithium-ion pathways between the anode and the cathode. The electrolyte is an ionic conductor. Furthermore, the electrolyte is an electronically insulating material.

[0004] One of the factors that determine the economic viability of a battery cell is its capacity and cycle life. A battery cell for an electric vehicle may need to last for at least 30,000 operating hours. These demanding requirements can pose a challenge for the vehicle's battery cell(s). DESCRIPTION

[0005] An electrolyte composition for batteries according to one or more embodiments is provided. The electrolyte composition comprises a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, a lithium salt derivative thereof, or a combination thereof.

[0006] In some embodiments, the Li salt derivative thereof is lithium bis(trimethylsilyl)phosphate.

[0007] In some embodiments, the partially substituted phosphite additive is bis(trimethylsilyl)phosphite.

[0008] In some embodiments, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 wt.%, based on the total weight of the electrolyte composition.

[0009] In some embodiments, the partially substituted phosphite additive is present in an amount of about 1 to about 5 wt.%, based on the total weight of the electrolyte composition.

[0010] In some embodiments, the partially substituted phosphite additive is present in an amount of about 2 to about 4 wt.%, based on the total weight of the electrolyte composition.

[0011] In some embodiments, the electrolyte composition includes co-additives.

[0012] In some embodiments, the co-additives comprise one or more lithium-based compounds selected from LiPO2F2, LiTFSI, LiFSI, LiDFOB, LiBOB or a combination thereof.

[0013] In some embodiments, one or more lithium-based compounds are present in an amount of approximately 0.1 to approximately 2 wt.%, based on the total weight of the electrolyte composition.

[0014] In some embodiments, the co-additives comprise one or more phosphorus- and silicon-based additives selected from tris(trimethylsilyl)phosphite, tris(trimethylsilyl)phosphate or a combination thereof.

[0015] In some embodiments, one or more phosphorus- and silicon-based additives are present in an amount of approximately 0.1 to approximately 2 wt.%, based on the total weight of the electrolyte composition.

[0016] In some embodiments, the solvent is selected from fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, 2,2,2-trifluoroethyl methyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate or a combination thereof.

[0017] A battery according to one or more embodiments is provided. The battery comprises an anode and a cathode made of lithium- and manganese-rich layered oxides (LMR). An electrolyte composition is arranged between the anode and the LMR cathode. The electrolyte composition comprises a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, a lithium salt derivative thereof, or a combination thereof.

[0018] In some embodiments, the LMR cathode comprises LixMnyNiZO2, where x is from 1.1 to 1.5, y is from 0.8 to 0.6 and z is from 0.2 to 0.4.

[0019] In some embodiments, the LMR cathode also contains LFMP, LFP, NCMA, NMC, NCA, LNMO or a combination thereof.

[0020] In some embodiments, the anode comprises SiOx / graphite, graphite, Si, SiOx, lithium metal or a combination thereof, where x is a value greater than 0.

[0021] In some embodiments, the anode and the LMR cathode have a negative to positive ratio (N / P) of about 1 to about 3.

[0022] In some embodiments, the battery is configured to operate within a voltage range of approximately 2.0 to approximately 5.0 V.

[0023] In some embodiments, the battery is configured to be charged at a charging rate of approximately C / 100 to approximately 6C.

[0024] A device according to one or more embodiments is provided. The device comprises an output component and a battery configured to supply electrical energy to the output component. The battery includes an anode and a cathode made of lithium- and manganese-rich layered oxides (LMRs). An electrolyte composition is arranged between the anode and the LMR cathode. The electrolyte composition comprises a solvent selected from fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, 2,2,2-trifluoromethyl methyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate, or a combination thereof. The electrolyte composition further comprises a partially substituted phosphite additive selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, a lithium salt derivative thereof, or a combination thereof.The partially substituted phosphite additive is present in an amount of approximately 0.1 to approximately 5 wt%, based on the total weight of the electrolyte composition.

[0025] The aforementioned features and advantages, as well as further features and advantages of the present disclosure, are readily apparent from the following detailed description of the best embodiments of the disclosure in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 schematically shows an exemplary battery cell with an anode, a cathode, a separator and an electrolyte composition according to the present disclosure; Fig. Figure 2 schematically shows an exemplary device with a battery pack containing a plurality of battery cells, according to the present disclosure; Fig. Figure 3 is a diagram showing exemplary test results comparing the capacity retention of a battery cell with a number of charge / discharge cycles through which the battery cell is operated at 4.4 volts (V), with a variety of different electrolyte compositions according to the present disclosure; and Fig. Figure 4 is a diagram showing exemplary test results comparing the capacity retention of a battery cell with a number of charge / discharge cycles through which the battery cell is operated at 4.6 V, with a variety of different electrolyte compositions according to the present disclosure. DETAILED DESCRIPTION

[0026] As required, detailed embodiments of the present disclosure are disclosed here; however, it should be understood that the disclosed embodiments are merely exemplary of the disclosure, which can be embodied in various and alternative forms. The illustrations are not necessarily to scale; some features may be exaggerated or reduced in size to show details of certain components. Therefore, specific structural and functional details disclosed here are not to be understood as limiting, but merely as a representative basis to show a person skilled in the art how to apply the present disclosure in various ways.

[0027] Unless explicitly stated otherwise in the context as used herein, the term "approximately" is understood here to mean within a normal tolerance range, e.g., within two standard deviations of the mean. "Approximately" can be understood as within 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value.

[0028] "Approximately" can also be understood to mean that the exact value is given. Unless the context indicates otherwise, the numerical values ​​given here are modified by the term "approximately".

[0029] Lithium (Li)- and manganese (n)-rich (LMR) layered oxide cathode materials with high capacity and power are useful for a lithium-ion energy storage system that powers a battery-electric vehicle. Such an energy storage system can be described as a high-energy-density battery. The battery cells can contain a silicon and / or graphite-containing anode and an LMR cathode.

[0030] The capacity and cycle life of the battery cells can vary depending on the operating conditions. The performance of the battery cells can also vary depending on the choice of cathode and anode materials. An electrolyte composition disclosed herein provides excellent cycle life for the battery cells. In one embodiment, the electrolyte composition comprises a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, a lithium salt derivative thereof, or a combination thereof. In one or more embodiments of the disclosure, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5% by weight, based on the total weight of the electrolyte composition.

[0031] Testing has shown that the addition of the partially substituted phosphite additive in the described weight proportions improves the formation of a solid electrolyte interface (SEI) on the electrode(s), e.g., the LMR cathode, and forms an excellent protective layer on both the LMR cathode and the anode. An SEI can form on the surface of the LMR cathode. An SEI arises from a chemical reaction between the LMR cathode and a liquid or gel electrolyte interacting with the cathode. The SEI forms as a film on the LMR cathode and improves the cycle life of the battery cell.

[0032] Referring to the drawings, in which the same reference numbers refer to the same features in the different views, shows Fig. Figure 1 schematically shows an exemplary battery cell 100 with an anode 110, a cathode 120, a separator 130, and an electrolyte composition 140. The battery cell 100 enables the conversion of electrical energy into stored chemical energy in a charge cycle, and the battery cell 100 enables the conversion of stored chemical energy into electrical energy in a discharge cycle. A negative current collector 112 is connected to the anode 110, and a positive current collector 122 is connected to the cathode 120. The separator 130 can be operated to separate the anode 110 from the cathode 120 and allow ion transfer through the separator 130. The electrolyte composition 140 is a liquid or gel that forms a lithium-ion conduction path between the anode 110 and the cathode 120.

[0033] The anode 110 can consist of silicon, a silicon alloy, or another silicon-containing material (e.g., SiOx, where x is a value greater than 0) and / or a graphite or graphite-containing material and / or lithium metal. The cathode 120 can be composed of an active cathode material made of lithium- and manganese-rich layered oxides (LMR). In one embodiment, the cathode 120 is an LMR cathode containing an active LMR cathode material with the chemical formula LixMnyNizO2, where x is between 1.1 and 1.5, y is between 0.8 and 0.6, and z is between 0.2 and 0.4. The LMR cathode can further contain other active cathode materials, such as... B. LFMP (lithium iron manganese phosphate), LFP (lithium iron phosphate, e.g., LiFePO4), NCMA (nickel manganese cobalt aluminum oxide), NMC (nickel manganese cobalt oxide), NCA (nickel cobalt aluminum oxide) and / or LNMO (e.g., spinel LiNi) 0,5 Mn 1,5O4). In an exemplary embodiment, the LMR cathode contains approximately 92 wt% or more of active cathode material with a loading per unit area of ​​approximately 10 to approximately 30 mg / cm². In an exemplary embodiment, the anode 110 and the cathode 120 have a negative to positive ratio (N / P) of approximately 1 to approximately 3.

[0034] In one or more embodiments of the disclosure, the electrolyte composition 140 comprises a solvent and a partially substituted phosphite additive selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite (BTMSPi), a Li salt derivative thereof, or a combination thereof. As described in Fig. As shown in Figure 1, the partially substituted phosphite additive in an exemplary embodiment has the chemical formula I, where, when x = hydrogen (H), formula I defines the chemical structure for bis(trimethylsilyl)phosphite, and when x = lithium (Li), formula I defines the chemical structure for lithium bis(trimethylsilyl)phosphate, which is a Li salt derivative of bis(trimethylsilyl)phosphite. In an exemplary embodiment, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 wt%, e.g., about 1 to about 5 wt%, e.g., about 2 to about 4 wt%, e.g., about 3 wt%, based on the total weight of the electrolyte composition 140.

[0035] The electrolyte composition 140 may also contain other co-additives. Non-limiting examples of different co-additives are one or more lithium-based compounds and / or one or more phosphorus- and silicon-based additives. Non-limiting examples of lithium-based compounds are LiPO₂F₂ (lithium difluorophosphate), LiTFSI (lithium bis(trifluoromethane)sulfonimide), LiFSI (lithium bis(fluorosulfonyl)imide), LiDFOB (lithium difluoro(oxalato)borate), and / or LiBOB (lithium bis(oxalato)borate). In an exemplary embodiment, the one or more lithium-based compounds are present in an amount of about 0.1 to about 2 wt%, based on the total weight of the electrolyte composition 140. Non-limiting examples of phosphorus- and silicon-based additives are tris(trimethylsilyl)phosphite and / or tris(trimethylsilyl)phosphate.In an exemplary embodiment, one or more phosphorus- and silicon-based additives are present in an amount of about 0.1 to about 2 wt.%, based on the total weight of the electrolyte composition 140.

[0036] Non-restrictive examples of solvents in electrolyte composition 140 are fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, propylene carbonate, 2,2,2-trifluoroethyl methyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, and / or 3,3,3-trifluoropropylene carbonate. In one example, the solvent comprises a cyclic carbonate, for example, ethylene carbonate (EC), and a linear carbonate, for example, dimethyl carbonate.

[0037] In one exemplary embodiment, the battery cell 100 is configured to operate within a voltage range of approximately 2.0 to approximately 5.0 V. In another exemplary embodiment, the battery cell 100 is configured to be charged at a charging rate of approximately C / 100 to approximately 6C.

[0038] The battery cell 100 can be used in a wide range of applications and powertrains. Fig. Figure 2 schematically shows an exemplary device 200, e.g., a battery-powered electric vehicle (BEV), with a battery pack 210 containing a plurality of battery cells 100. The multiple battery cells 100 can be connected to one another in various combinations, e.g., by connecting some in parallel and some in series to supply electrical energy at a desired voltage. The battery pack 210 is shown electrically connected to a motor-generator unit 220, which serves to supply the vehicle 200 with motive power. The motor-generator unit 220 can include an output component, e.g., an output shaft, which is supplied with mechanical energy to provide the motive power for the vehicle 200. A number of variants of the vehicle 200 are conceivable, and the disclosure is not intended to be limited to the examples given.

[0039] Fig. Figure 3 is a diagram 300 showing exemplary test results of a relationship between the maintenance of a battery cell's discharge capacity and the number of charge / discharge cycles to which the battery cell is operated. A vertical axis 304 describes the discharge capacity in units of mAh / cm², and the vertical axis 305 describes the maintenance of the discharge capacity as a percentage (%). A horizontal axis 302 describes the number of charge / discharge cycles. As shown in the figure, line 310 represents the base electrolyte composition, line 312 represents the base electrolyte composition modified with 1% TTMSPi, and line 314 represents the base electrolyte composition modified with 1% BTMSPi, each at the higher initial discharge capacity.Similarly, line 320 represents the base electrolyte composition, line 322 the base electrolyte composition modified with 1% TTMSPi, and line 324 the base electrolyte composition modified with 1% BTMSPi, all at the lower initial discharge capacity. As shown in diagram 300, the electrolyte containing the bisphosphite additive (BTMSPi) exhibits a better cycle life during cyclic operation at an upper cutoff voltage of 4.4 V than the base system or conventional systems with trimethylsilylphosphite additive (TTMSPi).

[0040] Fig.Figure 4 is a diagram 400 that presents exemplary test results for the relationship between the capacity retention of a battery cell and the number of charge / discharge cycles to which the battery cell is operated. A vertical axis 404 describes the discharge capacity in units of mAh / cm², and the vertical axis 405 describes the retention of the discharge capacity as a percentage (%). A horizontal axis 402 describes the number of charge / discharge cycles. As shown in the figure, line 410 represents the base electrolyte composition, line 412 represents the base electrolyte composition modified with 1% BTMSPi, and line 414 represents the base electrolyte composition modified with 3% BTMSPi, in each case at the higher initial discharge capacity.Similarly, line 420 represents the base electrolyte composition, line 422 the base electrolyte composition modified with 1% BTMSPi, and line 424 the base electrolyte composition modified with 3% BTMSPi, all at the lower initial discharge capacity. As shown in diagram 400, the bisphosphite additive (BTMSPi) exhibits a significantly better cycle life than the base electrolyte (without any additive), even at the higher cutoff voltage of 4.6 V. Furthermore, the high-voltage performance depends on the actual concentration of the bisphosphite additive (BTMSPi). Increasing the concentration from 1% to 3% significantly improves the cycle performance at 4.6 V.

[0041] While the best modes for carrying out the disclosure have been described in detail, those who are familiar with the prior art to which this disclosure relates will recognize various alternative designs and embodiments for carrying out the disclosure within the scope of the attached claims.

Claims

[1] An electrolyte composition for batteries, wherein the electrolyte composition comprises: a solvent; and a partially substituted phosphite additive selected from mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, a Li salt derivative thereof, or a combination thereof. [2] Electrolyte composition according to claim 1, wherein the Li salt derivative thereof is lithium bis(trimethylsilyl)phosphate. [3] The electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is bis(trimethylsilyl)phosphite. [4] Electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 wt.%, based on the total weight of the electrolyte composition. [5] Electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 1 to about 5 wt%, based on the total weight of the electrolyte composition. [6] Electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 2 to about 4 wt%, based on the total weight of the electrolyte composition. [7] Electrolyte composition according to claim 1, further comprising co-additives. [8] Electrolyte composition according to claim 7, wherein the co-additives comprise one or more lithium-based compounds selected from LiPO2F2, LiTFSI, LiFSI, LiDFOB, LiBOB or a combination thereof. [9] Electrolyte composition according to claim 8, wherein the one or more lithium-based compounds are present in an amount of about 0.1 to about 2 wt%, based on the total weight of the electrolyte composition. [10] Electrolyte composition according to claim 7, wherein the co-additives comprise one or more phosphorus- and silicon-based additives selected from tris(trimethylsilyl)phosphite, tris(trimethylsilyl)phosphate or a combination thereof.

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