Nonaqueous solvent electrolyte compositions for energy storage devices

Abstract

To provide energy storage devices comprising improved electrolyte compositions, where improved performance may be realized as improved discharge rate cycling, improved capacity, improved Coulombic efficiency, or improved capacity upon cycling.SOLUTION: An energy storage device comprises: a cathode comprising a cathode active material; an anode comprising an anode active material; a separator between the cathode and the anode; and an electrolyte comprising a lithium salt and a non-aqueous electrolyte solvent composition. The non-aqueous electrolyte solvent composition comprises ethylene carbonate (EC) and dimethylcarbonate (DMC), where the volume ratio of EC to DMC is between 1:0.1 and 1:4. At least one of the cathode and the anode is substantially free from solvent residues.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 588,174, filed November 17, 2017, entitled "Non-aqueous Solvent Electrolytes for Dry Cell Electrodes and Compositions Thereof," the disclosure of which is incorporated herein in its entirety.

[0002] The present invention relates generally to energy storage devices, and more particularly to improved electrolyte compositions for use in energy storage devices. [Background technology]

[0003] Electrical energy storage batteries are widely used to power electronic, electromechanical, electrochemical, and other useful devices. Such batteries include primary chemical batteries, secondary (rechargeable) batteries, fuel cells, and various types of capacitors, including ultracapacitors. Increasing the operating voltage and temperature of energy storage devices such as capacitors is desirable to enhance energy storage performance, increase power performance, and broaden practical use cases. Summary of the Invention [Problem to be solved by the invention]

[0004] Lithium-ion batteries have been relied upon as a power source in many commercial and industrial applications, including consumer devices, productivity equipment, and battery-powered vehicles. However, the demand for energy storage devices is continually and rapidly increasing. For example, the automotive industry is developing vehicles that rely on compact and efficient energy storage, such as plug-in hybrids and pure electric vehicles. While lithium-ion batteries are well-suited to meet future demands, improvements in energy density are needed to provide longer-life batteries that can travel longer distances on a single charge.

[0005] The electrolyte is one of the key components that determine the electrochemical performance and safety of conventional lithium-ion batteries. The compatibility of the electrodes and electrolyte determines the battery performance to some extent. As electrodes become thicker and / or heavier, the electrolyte system plays a critical role in achieving high performance in batteries. [Means for solving the problem]

[0006] For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects of the invention and its advantages are described herein. Not all such objects or advantages may be achieved in any particular embodiment of the invention. Thus, for example, one skilled in the art will recognize that the invention can be embodied or practiced in a manner that achieves or optimizes one or a group of advantages taught herein without necessarily achieving other objects or advantages taught or suggested herein.

[0007] In a first aspect, an energy storage device can include the improved electrolyte compositions provided herein. In some embodiments, the energy storage device is a lithium ion battery.

[0008] One embodiment includes a cathode comprising a cathode active material, a cathode comprising an anode active material, a separator between the cathode and the anode, and an electrolyte having a lithium salt and a non-aqueous electrolyte solvent composition, the non-aqueous electrolyte solvent composition comprising ethylene carbonate (EC) and an additional solvent selected from at least one of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and propylene carbonate (PC). The volume ratio of EC to the additional solvent is 1:2 to 1:4.

[0009] Another embodiment is a method for manufacturing an energy storage device, the method comprising providing a housing, disposing in the housing an anode, a cathode, and a separator between the anode and the cathode, wherein at least one of the anode and the cathode is free of solvent residue, and disposing in the housing an electrolyte having a lithium salt and a non-aqueous electrolyte solvent composition, the non-aqueous electrolyte solvent composition including ethylene carbonate (EC) and an additional solvent selected from at least one of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and propylene carbonate (PC), wherein the volume ratio of EC to the additional solvent is 1:2 to 1:4.

[0010] All of these embodiments are intended to be within the scope of the invention disclosed herein. These and other embodiments of the invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, and it is to be understood that the invention is not limited to the specific preferred embodiments disclosed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a longitudinal cross-sectional view illustrating an exemplary embodiment of an energy storage device having an improved electrolyte composition. [Figure 2] FIG. 2 shows an embodiment of an energy storage device having an improved electrolyte composition. [Figure 3A] FIG. 3A shows the charge and discharge capacity of a natural graphite electrode in a half-cell format according to Example 1. [Figure 3B] FIG. 3B shows the coulombic efficiency of the half-cell natural graphite electrode according to Example 1. [Figure 4A] FIG. 4A shows the charge and discharge capacity of the artificial graphite electrode manufactured by the dry battery electrode process 1 with a half-cell structure according to Example 1. [Figure 4B] FIG. 4B shows the charge and discharge capacity of the artificial graphite electrode manufactured by the dry battery electrode process 2 with a half-cell structure according to Example 1. [Figure 5]FIG. 5 shows the charge and discharge capacity of the artificial graphite electrode manufactured by Process 3 of the half-cell structure according to Example 1. [Figure 6A] FIG. 6A shows the charge and discharge capacity of the half-cell type flaky artificial graphite electrode according to Example 1. [Figure 6B] FIG. 6B shows the coulombic efficiency of the half-cell type thin flake artificial graphite electrode according to Example 1. [Figure 7A] FIG. 7A shows the charge and discharge capacity of the NMC / graphite full cell according to Example 1. [Figure 7B] FIG. 7B shows the coulombic efficiency of the NMC / graphite full cell according to Example 1. [Figure 8A] FIG. 8A shows the charge and discharge capacity of NMC811 / graphite full cells of compositions 1 and 3 according to Example 2. [Figure 8B] 8B shows the charge and discharge capacity of NMC622 / graphite full cells of compositions 1 and 3 according to Example 2. [Figure 8C] FIG. 8C shows the coulombic efficiency of NMC811 / graphite and NMC622 / graphite full cells of compositions 1 and 3 according to Example 2. [Figure 9A] FIG. 9A shows the discharge capacity retention of an NMC622 / graphite full cell having an electrolyte of Composition 1 according to Example 2. [Figure 9B] FIG. 9B shows the charge capacity retention of the NMC622 / graphite full cell having the electrolyte of Composition 1 according to Example 2. [Figure 10A] FIG. 10A shows the discharge capacity retention of an NMC622 / graphite full cell having an electrolyte of composition 3 according to Example 2. [Figure 10B] FIG. 10B shows the charge capacity retention of the NMC622 / graphite full cell having the electrolyte of composition 3 according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] As used herein, the terms "battery" and "capacitor" are given their ordinary and customary meanings to those skilled in the art. The terms "battery" and "capacitor" are not mutually exclusive. A capacitor or battery is a single electrochemical cell that operates alone or as a component of a multi-cell system.

[0013] As used herein, the voltage of an energy storage device is the operating voltage of a single battery or capacitor cell, which may be above the rated voltage, below the rated voltage under load, or vary due to manufacturing tolerances.

[0014] As described herein, a "self-supporting" electrode film or active layer is one that incorporates a binder matrix structure sufficient to support the film or layer and maintain its shape so that the electrode film or layer is self-supporting. When incorporated into an energy storage device, a self-supporting electrode film or active layer is one that incorporates such a binder matrix structure. Typically, and depending on the method used, such an electrode film or active layer has sufficient strength to be used in the energy storage device manufacturing process without the use of external support elements such as current collectors or other films. For example, a "self-supporting" electrode film can have sufficient strength to be wound, handled, and unwound during the electrode manufacturing process without other support elements.

[0015] As described herein, a "solvent-free" electrode film is one that does not contain detectable process solvents, process solvent residues, or process solvent impurities. Process solvents or conventional solvents include organic solvents. Dry electrode films, such as cathode or anode electrode films, can be solvent-free.

[0016] A "wet" or "wet process" electrode is an electrode manufactured by at least one process that includes a slurry of active material, binder, and processing solvent, processing solvent residues, and / or processing solvent impurities. Wet electrodes may optionally contain additives.

[0017] Various embodiments of the present invention relate to electrolyte compositions for energy storage devices with improved performance. The energy storage device may, in one embodiment, be a lithium-ion based battery.

[0018] One embodiment is an energy storage device having an improved non-aqueous electrolyte solvent blend. The improved electrolyte can improve the physical and chemical properties of the electrolyte, such as viscosity, wettability, and conductivity. The electrolyte's performance effects can be attributed in part to physical properties such as viscosity and wettability, and chemical or electrochemical properties such as the reactivity of the solvent on the electrode surface, e.g., the graphite surface. The shape of the active material particles can also play a role. For example, the graphite material particles can be spherical graphite (also known as potato graphite) or flake graphite.

[0019] In one embodiment, the electrolyte compositions enhance the electrochemical performance of electrodes, particularly dry-processed battery electrodes. The present disclosure provides electrolyte compositions for use with relatively thick or highly loaded battery electrodes. The discharge rate performance of the improved electrolyte compositions provided herein can be compared to typical lithium-ion battery electrolytes.

[0020] In one embodiment, the improved electrolyte composition can include a lithium salt, an electrolyte solvent such as a non-aqueous or organic solvent mixture, and, optionally, one or more additives. For example, the improved electrolyte can include one or more carbonates, such as ethylene carbonate (EC), propylene carbonate (PC), vinyl ethylene carbonate (VEC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and combinations thereof. The electrolyte can also include one or more acyclic carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof.

[0021] Generally, the lithium salt can include a redox-stable anion. In some embodiments, the anion can be monovalent. In some embodiments, the lithium salt can be selected from hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium bis(trifluoromethanesulfonyl)imide (LiN(SOCF)), lithium trifluoromethanesulfonate (LiSOCF), and combinations thereof. In some embodiments, the electrolyte can include an anion selected from the group consisting of hexafluorophosphate, tetrafluoroborate, and iodide. In some embodiments, the salt concentration can be from about 0.1 mol / L (M) to about 5 M, from about 0.2 M to about 3 M, or from about 0.3 M to about 2 M. In further embodiments, the salt concentration of the electrolyte can be from about 0.7 M to about 1 M. In certain embodiments, the salt concentration of the electrolyte may be about 0.2M, about 0.3M, about 0.4M, about 0.5M, about 0.6M, about 0.7M, about 0.8M, about 0.9M, about 1M, about 1.1M, about 1.2M, or any range of values ​​therebetween.

[0022] In some embodiments, the electrolyte of the energy storage device provided herein can include a liquid solvent. The solvent provided herein need not dissolve all components of the electrolyte, nor need to completely dissolve any component. In further embodiments, the solvent can be an organic solvent. In some embodiments, the solvent can include one or more functional groups selected from a carbonate group, an ether group, and / or an ester group. In some embodiments, the solvent can include a carbonate described herein. In further embodiments, the carbonate can be selected from cyclic carbonates such as, for example, ethylene carbonate (EC), propylene carbonate (PC), vinyl ethylene carbonate (VEC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), or a combination thereof, or can be selected from acyclic carbonates such as, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or a combination thereof. In certain embodiments, the electrolyte can include LiPF6 and one or more carbonates.

[0023] The electrolyte compositions provided herein can be further optimized by adjusting the ratio of individual solvents in a given composition. For example, an energy storage device can include a non-aqueous electrolyte solvent composition comprising ethylene carbonate (EC) and at least one additional solvent. In one embodiment, the additional solvent can include ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or propylene carbonate (PC). In some embodiments, the volume ratio of EC to the additional solvent is from about 1:2 to about 1:4, although other ranges are contemplated.

[0024] The electrolyte compositions provided herein may further include one or more additives. The additive may be, for example, a lithium salt or a liquid additive. Examples of lithium salts include LiClO, LiBF, CF, SO, N, LiSO, CF, and CF. 10 L iNO4S2 and combinations thereof, at various salt concentration ratios. The additives are selected to improve the SEI composition and increase wetting speed, and include, for example, vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, cyclohexane, and the like. In some embodiments, the electrolyte composition can include about 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 3%, 4%, 5%, or any range of values ​​therebetween.

[0025] In some embodiments, the electrolyte solvent can include an EC / EMC / DMC / PC solvent in a volume ratio of 1:2:0.1:0.02. In some embodiments, the electrolyte solvent can include an EC / DMC in a volume ratio of 1:3. In some embodiments, the electrolyte solvent can include an EC / EMC in a volume ratio of 1:3. In some embodiments, the electrolyte solvent can include an EC / EMC in a volume ratio of 1:2.4. In some embodiments, the electrolyte solvent can include an EC / EMC / DMC in a volume ratio of 1:0.5:3. In some embodiments, the electrolyte solvent can include an EC / EMC / DMC in a volume ratio of 1:1:1. In some embodiments, the electrolyte solvent can include an EC / EMC in a volume ratio of 1:4. In some embodiments, the electrolyte solvent can include an EC / DMC in a volume ratio of 1:4. In still other embodiments, the lithium salt can be present in the electrolyte at a concentration of about 0.1 M to about 2 M. For example, the lithium salt can be present in the electrolyte at a concentration of about 1 M to 1.3 M. In still other embodiments, the lithium salt is LiPF6.

[0026] In some embodiments, energy storage devices including electrolyte compositions as provided herein can exhibit higher discharge rate performance compared to energy storage devices without the improved electrolyte compositions. Such higher discharge rate performance is suitable for high-energy, high-power applications, such as electric vehicle propulsion. In conventional lithium-ion batteries, discharge rates below about C / 5 are typically managed with high-energy electrode designs, where C / 5 is the discharge current relative to the cell capacity that drains the cell in 5 hours. However, as electrodes become thicker (correlated with higher cell energy), electrolyte composition becomes more important to address discharge performance at higher C rates (1 C and above). In some embodiments, the disclosed electrolyte compositions exhibit discharge performance advantages, exhibiting higher energy retention at higher discharge currents. In some embodiments, the electrolyte compositions as provided herein exhibit high discharge rate performance.

[0027] Energy storage devices comprising the electrolyte compositions provided herein are characterized by improved capacity retention over the life of the device. Improved capacity retention can provide improved power density to the device over the life of the device. In further embodiments, energy storage devices comprising the electrolyte compositions provided herein can exhibit improved energy delivery at high C-rates. For example, improved energy delivery can be achieved at C-rates greater than 1. In some embodiments, energy storage devices can be provided that exhibit improved coulombic efficiency compared to energy storage devices comprising typical electrolytes. Further improvements achieved in various embodiments include improved storage stability during cycling and improved cycling performance, including reduced capacity degradation.

[0028] The electrolyte solvent and / or electrolyte additive can promote the formation of a solid electrolyte interlayer (SEI) on the surface of the electrolyte. One of the factors that causes the SEI to form is believed to be the decomposition of one or more components of the electrolyte. For example, the SEI can form at the interface between the anode and the electrolyte through a single-step or multi-step decomposition reaction that transfers electrons to one or more electrolyte components that form the SEI. An electrode with an SEI layer can be used for energy storage devices at lower anode potentials and / or at higher anode potentials. It is possible to indicate the potential at which operation is possible.

[0029] It is understood that the electrolyte compositions provided herein can be used in a variety of embodiments with many energy storage systems or devices, such as, for example, one or more batteries, capacitors, capacitor-battery hybrids, fuel cells, other energy storage systems or devices, or combinations thereof. In some embodiments, the electrolyte additives or electrolytes including the additives described herein may be implemented in lithium-ion batteries.

[0030] The energy storage devices provided herein may be of any suitable shape, such as, for example, flat, spirally wound, button-shaped, or pouch-shaped. The energy storage devices provided herein may be components of systems such as, for example, power generation systems, uninterruptible power supply systems (UPS), solar power generation systems, energy recovery systems, for example, for use in industrial machinery and / or transportation. The energy storage devices provided herein may be used to power various electronic devices and / or automobiles, including hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and / or electric vehicles (EVs).

[0031] FIG. 1 shows a longitudinal cross-section of one exemplary embodiment. The device includes a wound electrode unit 10, including first and second current collector sheets, impregnated with the improved electrolyte provided herein, and disposed in a case 30. The upper end of the case 30 facing the rubber cap 40 may be beaded or curled, thereby connecting them. A first terminal 21 extends through the upper surface 53 to the inner portion 41 and is connected to the wound electrode unit 10, which serves as a positive current collector. The first terminal 21 functions as a positive terminal. A second terminal 22 extends through the upper surface 53 to the second inner portion 42 and is connected to the negative current collector, which serves as a negative terminal. The rubber cap 40 is disposed inside the upper portion of the case 30 to prevent electrolyte leakage from the interior of the case 30 to the outside of the device.

[0032] 2 is a cross-sectional schematic diagram illustrating an exemplary energy storage device 100 including the improved electrolyte compositions provided herein. The energy storage device 100 may be classified as, for example, a capacitor, a battery, a capacitor-battery hybrid, or a fuel cell. In a preferred embodiment, the device 100 is a lithium-ion battery.

[0033] The device includes a first electrode 102, a second electrode 104, and a separator 106 disposed between the first electrode 102 and the second electrode 104. The first electrode 102 and the second electrode 104 are adjacent to opposite surfaces of the separator 106. The energy storage device 100 includes an improved electrolyte composition 118 to facilitate ionic transfer between the electrodes 102, 104 of the energy storage device 100. For example, the improved electrolyte composition 118 can be in contact with the first electrode 102, the second electrode 104, and the separator 106. The improved electrolyte composition 118, the first electrode 102, the second electrode 104, and the separator 106 are contained within an energy storage device housing 120.

[0034] The first electrode 102, the second electrode 104, and the separator 106, or one or more of their components, may comprise a porous material. The pores of the porous material can provide a containment structure for contacting the improved electrolyte composition 118 and / or increasing the surface area within the housing 120. The energy storage device housing 120 can be sealed around the first electrode 102, the second electrode 104, and the separator 106 and can be physically sealed from the external environment.

[0035] In some embodiments, the first electrode 102 is an anode (cathode) and the second electrode 104 The separator 106 may be a cathode (positive electrode). The separator 106 may be configured to electrically insulate two adjacent electrodes, such as the first electrode 102 and the second electrode 104, on opposite sides of the separator 106 while allowing ionic communication between the two adjacent electrodes. The separator 106 may comprise a suitable porous, electrically insulating material. In some embodiments, the separator 106 may comprise a polymeric material. For example, the separator 106 is a cellulosic material (e.g., paper), a polyethylene (PE) material, a polypropylene (PP) material, and / or a polyethylene and polypropylene material.

[0036] Generally, the first electrode 102 and the second electrode 104 each comprise a current collector and an electrode film. The electrodes 102, 104 each have a dense electrode film 112, 114. The dense electrode films 112, 114 may be of any suitable shape, size, and thickness. For example, the thickness of the electrode film may be The thickness may be about 30 microns (μm) to about 250 microns, e.g., about 50 microns, about 100 microns, about 150 microns, about 200 microns, about 250 microns, about 300 microns, about 400 microns, about 500 microns, about 750 microns, about 1000 microns, about 2000 microns, or any range of values ​​therebetween. Generally, the electrode film includes one or more active materials, such as the anode active material or cathode active material provided herein. The electrode films 112, 114 may be dry and / or free-standing electrode films provided herein and may have advantageous properties, such as thickness, energy density, specific energy density, areal energy, or areal capacity, as provided herein. The first electrode film 112 and / or the second electrode film 114 may include one or more binders, as provided herein. The electrode films 112, 114 are prepared by the methods provided herein. The electrode films 112 and / or 114 may be wet or self-supporting dry electrodes as provided herein.

[0037] As shown in FIG. 2 , the first electrode 102 and the second electrode 104 each include a first current collector 108 in contact with the dense first electrode film 112 and a second current collector 110 in contact with the dense second electrode film 114. The first current collector 108 and the second current collector 110 facilitate electrical coupling between the corresponding electrode film and an external electrical circuit (not shown). The first current collector 108 and / or the second current collector 110 can comprise one or more conductive materials and have any suitable shape and size selected to facilitate charge transfer between the corresponding electrode and the external electrical circuit. The current collectors may comprise metallic materials, including metals such as aluminum, nickel, copper, rhenium, niobium, tantalum, and precious metals, alloys, and combinations thereof, such as silver, gold, platinum, palladium, rhodium, osmium, and iridium. For example, the first current collector 108 and / or the second current collector can comprise aluminum foil or copper foil. The first current collector 108 and / or the second current collector 110 may be rectangular or approximately rectangular in shape sized to provide for the transfer of charge between the corresponding electrode and an external circuit.

[0038] In some embodiments, energy storage device 100 may be a lithium ion battery. In some embodiments, the electrode film of a lithium ion battery electrode can include one or more active materials and a fibrillated binder matrix provided herein.

[0039] In some embodiments, the lithium ion battery is configured to operate at about 2.5 to 4.5 V or about 3.0 to 4.2 V. In further embodiments, the lithium ion battery is configured to have a minimum operating voltage of about 2.5 V to about 3 V, respectively. In yet further embodiments, the lithium ion battery is configured to have a maximum operating voltage of about 4.1 V to about 4.4 V.

[0040] In some embodiments, the electrode films provided herein comprise at least one active material and The at least one active material may include at least one binder. The at least one active material may be any active material known in the art. The at least one active material may be a material suitable for use in an anode or cathode of a battery.

[0041] In some embodiments, an electrode film of a lithium-ion energy storage device can include an anode active material. In some embodiments, the anode active material can include, for example, an intercalating material such as carbon, graphite, and / or graphene; an alloying or dealloying material such as silicon, silicon oxide, tin, and / or tin oxide; a metal alloy or compound such as silicon-aluminum and / or silicon-tin; and / or a conversion material such as manganese oxide, molybdenum oxide, nickel oxide, and / or copper oxide. The anode active materials can be used alone or in combination to form multiphase materials (e.g., Si—C, Sn—C, SiOx—C, SnOx—C, Si—Sn, Si—SiOx, Sn—SnOx, Si—SiOx—C, Sn—SnOx—C, Si—Sn—C, SiOx—SnOx—C, Si—SiOx—Sn, or Sn—SiOx—SnOx).

[0042] In some embodiments, the electrode film of the lithium-ion energy storage device can include a cathode active material. In some embodiments, the cathode active material can include a metal oxide, a metal sulfide, or a lithium metal oxide. The lithium metal oxide can include, for example, lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium titanate (LTO), and / or lithium nickel cobalt aluminum oxide (NCA). In some embodiments, the cathode active material can include, for example, LiCoO (LCO), Li(NiMnCo)O (NMC), and / or LiNi 0.8 Co 0.15 Al 0.05 Layered transition metal oxides such as LiMnO2 (NCA), LiMn2O4 (LMO) and / or LiMn 1.5 Ni 0.5 The cathode active material can include spinel manganese oxides such as O4 (LMNO), olivine such as LiFePO4, silicon, silicon oxide (SiOx), aluminum, tin, tin oxide (SnOx), manganese oxide (MnOx), molybdenum oxide (MoO2), molybdenum disulfide (MoS2), nickel oxide (NiOx), or copper oxide (CuOx). The cathode active material can include sulfur or a sulfur-containing material such as lithium sulfide (Li2S), or other sulfur-based materials, or mixtures thereof. In some embodiments, the cathode film includes a material containing sulfur or a material containing a sulfur active material in a concentration of at least 50% by weight. In some embodiments, the cathode film includes a material containing sulfur or a sulfur active material further including a binder. In some embodiments, the binder of the cathode membrane comprising a material containing sulfur or a sulfur active material is selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly(ethylene oxide) (PEO), polyethylene (PE), polyacrylic acid (PAA), gelatin, other thermosetting resins, or combinations thereof.

[0043] Anode active materials include common natural graphite, synthetic or artificial graphite, surface-modified graphite, spherical graphite, flake graphite, and mixtures or combinations of these types of graphite, elemental metals, and metal-C compounds for the anode.

[0044] As mentioned above, the type and shape of the anode active material and electrolyte solvent composition used in an energy storage device can affect the performance of the energy storage device. The electrochemical performance of an anode electrode utilizing a particular electrolyte composition can be attributed to physical properties such as viscosity and wettability, and chemical or electrochemical properties of the electrolyte composition, such as the reactivity of the solvent on the anode active material surface. For example, the particle shape and particle size of graphite powder affect the powder surface area available to the electrolyte. Differences in the amount of surface area can affect the magnitude of irreversible electrochemical reactions of electrolyte components on the graphite particle surface. Without being bound by theory, it is believed that solvent decomposition is the primary irreversible reaction during the initial lithiation process. It is believed to be carried out on graphite particles. Typical Li / Li + The reduction potentials are EC = 1.36 V, DMC = 1.32 V, DEC = 1.32 V, EMC < 1.32 V, and PC = 1.0-1.6 V, depending on the solvent involved.

[0045] Generally, flaky particles have a large surface area compared to that of spherical particles. Furthermore, in some embodiments, the use of a cyclic carbonate (i.e., EC) in the electrolyte composition can increase the viscosity of the solvent mixture. In some embodiments, increasing the viscosity of the electrolyte stabilizes the solid electrolyte interlayer (SEI) on the graphite particles, allowing for operation at relatively low voltages. In some embodiments, the use of a linear carbonate (i.e., DMC) in the electrolyte composition can decrease the viscosity of the solvent mixture. In some embodiments, decreasing the viscosity of the electrolyte improves the ionic conductivity of the electrolyte solvent.

[0046] In some embodiments, the use of an EC-based, EMC-rich electrolyte composition with a spherical graphite anode active material improves electrochemical performance. In some embodiments, the use of an EC-based, EMC-rich electrolyte composition with a natural graphite anode active material improves electrochemical performance. In some embodiments, the use of an EC-based, EMC-rich electrolyte composition with a surface-modified artificial graphite anode active material improves electrochemical properties. In some embodiments, the use of an EC-based, EMC-rich electrolyte composition with an exfoliated artificial graphite anode active material improves electrochemical performance. In some embodiments, the use of an EC-based, DMC-rich electrolyte composition with an exfoliated graphite anode active material improves electrochemical properties. In some embodiments, the use of an EC-based, DMC-rich electrolyte composition with an exfoliated artificial graphite anode active material improves electrochemical properties.

[0047] The at least one active material may include one or more carbon materials. The carbon materials may be selected from, for example, graphite materials, graphite, graphene-containing materials, hard carbon, soft carbon, carbon nanotubes, porous carbon, conductive carbon, or combinations thereof. The activated carbon may be obtained from a steam process or an acid / etching process. In some embodiments, the graphite material may be a surface-treated material. In some embodiments, the porous carbon may include activated carbon. In some embodiments, the porous carbon may include structured carbon nanotubes, structured carbon nanowires, and / or structured carbon nanosheets. In some embodiments, the porous carbon may include graphene sheets. In some embodiments, the porous carbon may be a surface-treated carbon.

[0048] In some embodiments, a cathode electrode film for a lithium-ion battery or hybrid energy storage device may comprise about 70 wt % to about 98 wt %, including about 70 wt % to about 92 wt %, or about 70 wt % to about 96 wt % of at least one active material. In some embodiments, a cathode electrode film may comprise about 10 wt % or less of a porous carbon material, including about 5 wt % or less, or about 1 wt % to about 5 wt %. In some embodiments, a cathode electrode film may comprise about 5 wt % or less of a conductive additive, including about 1 wt % to about 3 wt %. In some embodiments, a cathode electrode film may comprise about 20 wt % or less of a binder, such as, for example, about 1.5 wt % to 10 wt %, about 1.5 wt % to 5 wt %, or about 1.5 wt % to 3 wt %. In some embodiments, a cathode electrode film may comprise about 1.5 wt % to about 3 wt % of a binder.

[0049] In some embodiments, the anode electrode film can include at least one active material, a binder, and optionally, a conductive additive. In some embodiments, the conductive additive can include a conductive carbon additive, such as carbon black. In some embodiments, at least one of the anode active materials can include synthetic graphite, natural graphite, hard carbon, soft carbon, graphene, mesoporous carbon, silicon, silicon oxide, tin, tin oxide, germanium, lithium titanate, a mixture, or a composite of any of the foregoing. In some embodiments, the anode electrode film can include about 80% to about 98% by weight, including about 80% to about 98% by weight, or about 94% to about 97% by weight, of at least one active material. In some embodiments, the anode electrode film includes about 5% by weight or less, including about 1% to about 3% by weight, of a conductive additive. In some embodiments, the anode electrode film includes about 20% by weight or less, including about 1.5% to 10% by weight, about 1.5% to 5% by weight, or about 3% to 5% by weight, of a binder. In some embodiments, the anode electrode film includes about 4% by weight of a binder. In some embodiments, the anode electrode film does not include a conductive additive.

[0050] Some embodiments include an electrode membrane, such as an anode or cathode, having one or more active layers comprising a polymeric binder material. The binder can include polytetrafluoroethylene (PTFE), polyolefin, polyalkylene, polyether, styrene butadiene, polysiloxane and copolymers of polysiloxane, branched polyether, polyvinyl ether, copolymers thereof, and / or mixtures thereof. The binder can include cellulose, such as carboxymethyl cellulose (CMC). In some embodiments, the polyolefin can include polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), copolymers thereof, and / or mixtures thereof. For example, the binder can include polyvinylidene chloride, poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), poly(ethylene oxide) (PEO), poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), polydimethylsiloxane (PDMS), polydimethylsiloxane-coalkylmethylsiloxane, copolymers thereof, and / or mixtures thereof. In some embodiments, the binder includes a fibrillizable polymer. In certain embodiments, the binder includes, consists essentially of, or consists of PTFE.

[0051] In some embodiments, the binder comprises PTFE and, optionally, one or more additional binder components. In some embodiments, the binder comprises one or more polyolefins, and / or copolymers thereof, and PTFE. In some embodiments, the binder comprises PTFE and one or more celluloses, polyolefins, polyethers, polyether precursors, polysiloxanes, copolymers thereof, and / or mixtures thereof. The mixture of polymers can comprise an interpenetrating network of the aforementioned polymers or copolymers.

[0052] The binder can include various suitable ratios of polymer components. For example, PTFE can be present in an amount of about 100% by weight or less, such as about 20% to about 95% by weight, about 20% to about 90% by weight, about 20% to about 80% by weight, about 30% to about 70% by weight, about 30% to about 50% by weight, or about 50% to about 90% by weight. In further embodiments, the binder can include PTFE, CMC, and PVDF as binders. In certain embodiments, the electrode membrane can include 2% by weight of PTFE, 1% by weight of CMC, and 1% by weight of PVDF. For example, the binder mixture can include PTFE in an amount that is 50% of the total binder volume of the electrode membrane and 2% of the total weight of the electrode membrane.

[0053] In some embodiments, the electrode film mixture can include binder particles selected in size, such as about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1000 nm, about 1100 nm, about 1200 nm, about 1300 nm, about 1400 nm, about 1500 nm, about 1600 nm, about 1700 nm, about 1800 nm, about 1900 nm, about 2100 nm, about 2200 nm, about 2300 nm, about 2400 nm, about 2500 nm, about 2600 nm, about 2700 nm, about 2800 nm, about 2 It can be 450 nm, about 500 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 10 μm, about 50 μm, about 100 μm, and any range of values ​​therebetween.

[0054] As used herein, a dry manufacturing process can refer to a process for forming an electrode film without or substantially without the use of solvents. For example, components of an active layer or electrode film, including a carbon material and a binder, can include dry particles. The dry particles forming the active layer or electrode film can be mixed to obtain a dry particle active layer mixture. In some embodiments, the active layer and electrode film can be formed from a dry particle active layer mixture in which the weight percentages of the components of the active layer or electrode film are approximately the same as the weight percentages of the components of the dry particle active layer mixture. An active layer or electrode film formed from a dry particle active layer mixture using a dry manufacturing process is free of, or substantially free of, processing additives, such as solvents and solvent residues resulting therefrom. In some embodiments, the resulting active layer or electrode film is a self-supporting film formed from a dry particle mixture using a drying process. In some embodiments, the resulting active layer or electrode film is a free-standing film formed from a dry particle mixture using a drying process. The process for forming the active layer or electrode film can include fibrillating a fibrillizable binder component, such as a film containing a fibrillated binder. In further embodiments, a free-standing active layer or electrode film can be formed without a current collector. In yet further embodiments, the active layer or electrode film can include a fibrillated polymer matrix, such as a self-supporting film. It is believed that the formation of a matrix, lattice, or network of fibrils can provide mechanical structure to the electrode film.

[0055] In some embodiments, the electrode film of the energy storage device that is a dry film and / or a self-supporting film has a mass per unit area of ​​the electrode film or current collector of about 12 mg / cm 2 , about 13mg / cm 2 , about 14mg / cm 2 , about 15mg / cm 2 , about 16mg / cm 2 , about 17mg / cm 2 , about 18mg / cm 2 , about 19mg / cm 2 , about 20mg / cm2 , about 21mg / cm 2 , about 22mg / cm 2 , about 23mg / cm 2 , about 24mg / cm 2 , about 25mg / cm 2 , about 26mg / cm 2 , about 27mg / cm 2 , about 28mg / cm 2 , about 29mg / cm 2 , about 30mg / cm 2 , about 50mg / cm 2 , about 60mg / cm 2 , about 70mg / cm 2 , about 80mg / cm 2 , about 90mg / cm 2 , about 100mg / cm 2 or any range of values ​​therebetween, the loading or active material loading can be provided.

[0056] In some embodiments, an energy storage device electrode film that is a dry film and / or a self-supporting film can provide a specific capacity, expressed as capacity per mass of active material, of 100 mAh / g, about 125 mAh / g, about 150 mAh / g, about 160 mAh / g, about 170 mAh / g, about 175 mAh / g, about 176 mAh / g, about 177 mAh / g, about 179 mAh / g, about 180 mAh / g, about 185 mAh / g, about 190 mAh / g, about 196 mAh / g, about 200 mAh / g, about 250 mAh / g, about 300 mAh / g, about 350 mAh / g, about 354 mAh / g, about 400 mAh / g, or any range of values ​​therebetween. In further embodiments, the electrode film of the energy storage device, which is a dry film and / or a self-supporting film, can provide a specific capacity, expressed as capacity per mass of the electrode film or current collector, of at least 100 mAh / g, or at least 150 mAh / g, or any range of values ​​therebetween. In some embodiments, the specific capacity is a charge capacity. In further embodiments, the specific capacity is a discharge capacity. In some embodiments, the electrode is an anode and / or a cathode. In some embodiments, the specific capacity is a first charge and / or discharge capacity. In some embodiments, the specific capacity is a charge and / or discharge capacity measured after a first charge and / or discharge.

[0057] In some embodiments, the self-supporting dry electrode films described herein can exhibit advantageously improved performance compared to typical electrode films, such as tensile strength, elasticity (elongation), bendability, coulombic efficiency, capacity, or conductivity. In some embodiments, the dry and / or self-supporting energy storage device electrode film can provide a first cycle coulombic efficiency of about 80%, 85%, 86%, 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, or at least any value in between, e.g., 90.1%, 90.5%, and 91.9%, or any value in between, expressed as a percentage of discharge capacity divided by charge capacity.

[0058] In some embodiments, an energy storage device electrode membrane that is a dry and / or self-supporting membrane, or an energy storage device electrode having a dry and / or self-supporting membrane, can provide a capacity retention of about or at least about 10%, about 20% or at least about 20%, about 30% or at least about 30%, about 40% or at least about 40%, about 50% or at least about 50%, about 60% or at least about 60%, about 70% or at least about 70%, about 80% or at least about 80%, about 90% or at least about 90%, about 98% or at least about 98%, about 99% or at least about 99%, about 99.9% or at least about 99.9%, about 100% or at least about 100%, or any range of values ​​therebetween, expressed as charge or discharge capacity at a predetermined ratio divided by charge or discharge capacity as measured at C / 10. In some embodiments, the charge or discharge rate for capacity retention is at least C / 10, C / 5, C / 3 (0.33C), C / 2, 1C, 1.5C, 2C, or any range therebetween. The charge or discharge rate for capacity retention can be measured at a set number of charge and discharge cycles after the first charge or discharge cycle. In some embodiments, the charge or discharge rate for capacity retention is measured at 1, 5, 10, 50, 100, 200, 300, 400, 500, 600, 700, 1000 cycles, or any number of cycles therebetween.

[0059] In some embodiments, the self-supporting dry electrode films described herein can exhibit advantageously improved performance, such as coulombic efficiency, capacity, or conductivity, compared to typical electrode films.

[0060] In the specific examples below, energy storage devices are prepared that include the electrolyte compositions described herein.

[0061] Example 1 The experiments shown in Example 1, which primarily consisted of electrolyte compositions containing EC, EMC, DMC, PC, and LiPF6 (see Table 1), evaluated the effects of electrode material, electrode composition, and dry electrode process on the electrochemical properties of half-cell as well as full-cell configurations. The proportion of EMC or DMC in each EC-based electrolyte solvent was found to determine, to some extent, the electrochemical performance of the anode electrode. For example, an EC-based, EMC-rich electrolyte solvent for a spherical graphite composition improved performance at high discharge rates. In addition, an EC-based, DMC-rich electrolyte solvent, when used with an exfoliated graphite composition, demonstrated improved performance at high discharge C rates.

[0062] The following six solvent compositions were developed and evaluated using dry-processed battery electrodes made with various active materials and electrode processing conditions to improve overall electrochemical performance. The improvements were based on the compatibility of the resulting electrolyte candidates with the designed dry-cell battery electrodes as well as the prevention of undesired reactions of the electrolyte on the dry-electrode surface.

[0063] EC-based solvent mixtures containing one or more solvents.

[0064] EC-based solvent mixtures containing one or more solvents in greater proportions than the standard EMC blend.

[0065] An EC-based solvent mixture containing one or more solvents in greater proportions than the standard DMC blend.

[0066] An EC-based solvent mixture containing one or more solvents in greater proportions than the standard DEC blend.

[0067] An EC-based solvent mixture containing one or more solvents in greater proportion than the standard PC blend.

[0068] EC-based solvent mixtures containing one or more solvents with equal blending ratios between them.

[0069] Commercially available non-aqueous solvents, including EC, EMC, DEC, DMC, PC, EA, and mixtures thereof, in various combinations, can be used without further purification. The volume ratios of the blended solvents detailed below, along with example compositions, are shown in Table 1.

[0070] [Table 1]

[0071] The resulting electrolyte compositions were evaluated in half and full cells with single-layer dry electrodes to assess the effect of solvent composition on electrode performance. The electrochemical performance of the cells was measured by a galvanostatic charge step followed by a potentiostatic step and a galvanostatic discharge step at room temperature.

[0072] To increase sensitivity to overall performance and advantages limited by wet coating techniques due to cracking, delamination, stiffness, etc., candidate electrolyte compositions were evaluated using thick dry electrodes as a benchmark. Preliminary experiments disclosed herein demonstrated a dry anode with a thickness of approximately 23 mg / cm. 2 , and about 45 mg / cm for dry cathodes. 2 An electrode load of 1000kJ / s was used.

[0073] The capacities and coulombic efficiencies of natural graphite-based anode half-cells using electrolyte compositions 1 and 3 are shown in Figure 3A and 3B, respectively. Figures 3A and 3B show composition 1 having a first charge capacity of about 360 mAh / g, a first discharge capacity of about 330 mAh / g, and an efficiency of about 91%, while composition 3 has a first charge capacity of about 380 mAh / g, a first discharge capacity of about 350 mAh / g, and an efficiency of about 92%. Figures 3A and 3B demonstrate that composition 3, which comprises an EMC-rich binary EC-EMC solvent, provides higher reversible capacity and efficiency than composition 1, which comprises an EMC-rich quaternary EC-EMC-DMC-PC solvent, in a natural graphite-based anode.

[0074] 4A and 4B show the charge and discharge capacities of surface-modified artificial graphite anode half-cells prepared using several electrolyte solvent systems and two different electrode compositions (Process 1 and Process 2). Figure 4A shows Composition 1, which has a first charge capacity of about 385 mAh / g and a first discharge capacity of about 325 mAh / g; Composition 2, which has a first charge capacity of about 310 mAh / g and a first discharge capacity of about 300 mAh / g; Composition 3, which has a first charge capacity of about 410 mAh / g and a first discharge capacity of about 350 mAh / g; Composition 4, which has a first charge capacity of about 315 mAh / g and a first discharge capacity of about 255 mAh / g; and Composition 5, which has a first charge capacity of about 365 mAh / g and a first discharge capacity of about 315 mAh / g. FIG. 4B shows Composition 1 having a first charge capacity of about 375 mAh / g and a first discharge capacity of about 335 mAh / g; Composition 2 having a first charge capacity of about 305 mAh / g and a first discharge capacity of about 350 mAh / g; Composition 3 having a first charge capacity of about 350 mAh / g and a first discharge capacity of about 395 mAh / g; Composition 3 has a first discharge capacity of about 415 mAh / g and a first charge capacity of about 31 Composition 4 shows a first discharge capacity of 5 mAh / g. The data show that EMC-rich systems such as Composition 1 and Composition 3 consistently exhibited improved charge and discharge capacity while maintaining similar coulombic efficiencies for electrodes prepared according to Processes 1 and 2. The compositions and specifications for Process 1 and Process 2 are shown in Table 2.

[0075] [Table 2]

[0076] Figure 5 shows the charge and discharge capacities of surface-modified artificial graphite anode half-cells prepared using the third electrode composition (Process 3) with several electrolyte solvent systems. Figure 5 shows Composition 1 having a first charge capacity of about 380 mAh / g and a first discharge capacity of about 335 mA / g, Composition 2 having a first charge capacity of about 320 Ah / g and a first discharge capacity of about 290 Ah / g, Composition 3 having a first charge capacity of about 385 Ah / g and a first discharge capacity of about 340 Ah / g, Composition 4 having a first charge capacity of about 310 Ah / g and a first discharge capacity of about 240 Ah / g, Composition 5 having a first charge capacity of about 375 Ah / g and a first discharge capacity of about 335 Ah / g, Composition 6 having a first charge capacity of about 390 Ah / g and a first discharge capacity of about 350 Ah / g, and Composition 7 having a first charge capacity of about 320 mAh / g and a first discharge capacity of about 290 mAh / g. The data show that relatively EMC-rich electrolyte solvent systems, such as Compositions 1, 3, and 6, were prepared according to Process 3. This demonstrates that the anode containing surface-modified artificial graphite provided high capacity. The composition and specifications of Process 3 are shown in Table 3 below.

[0077] [Table 3]

[0078] The capacities of exfoliated artificial graphite anode half-cells using electrolyte compositions 2 and 3 are shown in Figure 6A and Figure 6B, respectively. Figures 6A and 6B show composition 2 having a first charge capacity of about 330 mAh / g, a first discharge capacity of about 290 mAh / g, and an efficiency of about 85%, while composition 3 has a first charge capacity of about 350 mAh / g, a first discharge capacity of about 255 mAh / g, and an efficiency of about 70%. Figures 6A and 6B clearly show that, for exfoliated artificial graphite anodes, the DMC-rich composition 3 exhibits a higher charge capacity, but the efficiency of composition 3 is lower than that of the DMC-rich composition 2. Without being bound by theory, the improved coulombic efficiency of the relatively DMC-rich electrolyte system suggests that DMC can suppress irreversible reactions that occur during the use of the exfoliated artificial dry battery electrode.

[0079] The capacities of Compositions 1–5 used in full cells consisting of layered lithium nickel manganese cobalt oxide (NMC) as a dry cathode and surface-modified artificial graphite as a dry anode are shown in Figure 7A and Figure 7B, respectively. Figures 7A and 7B show that Composition 1 has a first charge capacity of about 175 mAh / g, a first discharge capacity of about 135 mAh / g, and an efficiency of about 78%; Composition 3 has a first charge capacity of about 185 mAh / g, a first discharge capacity of about 150 mAh / g, and an efficiency of about 80%; Composition 4 has a first charge capacity of about 165 mAh / g, a first discharge capacity of about 120 mAh / g, and an efficiency of about 74%; and Composition 5 has a first charge capacity of about 175 mAh / g, a first discharge capacity of about 140 mAh / g, and an efficiency of about 79%. 7A and 7B clearly demonstrate that composition 3 with a relatively EMC-rich electrolyte system significantly improves both the charge / discharge capacity and coulombic efficiency of NMC / graphite full cells.

[0080] Example 2 In Example 2, the electrochemical performance of full cells (NMC / Gr) incorporating an NMC cathode and a surface-modified artificial graphite (SMG-A5) anode incorporating electrolyte compositions 1 and 3 was investigated. The specifications of the cathode and anode electrodes and the electrolyte used in the full cells are shown in Table 4.

[0081] FIG. 8A shows the capacity of the NMC811 / Gr full cell, FIG. 8B shows the capacity of the NMC622 / Gr full cell, and FIG. 8C shows the capacity of the NMC811 / Gr and NMC622 / Gr full cells. Figures 8A and 8C show the efficiency of NMC811 / Gr full cells filled with the electrolytes of Composition 1 and Composition 3, respectively. The first cycle capacity and efficiency of the cells were calculated based on cycling the cells at a rate of 0.05 C and a cutoff voltage of 4.2 V for charge and 2.7 V for discharge. Figures 8A and 8C show the NMC811 / Gr full cells using the electrolyte of Composition 1 with a first charge capacity of about 217 mAh / g, a first discharge capacity of about 184 mAh / g, and an efficiency of about 84.7%, and the electrolyte of Composition 3 with a first charge capacity of about 218 mAh / g, a first discharge capacity of about 184 mAh / g, and an efficiency of about 84.6%. Figures 8B and 8C show NMC8622 / Gr full cells using the electrolyte of Formulation 1, which has a first charge capacity of about 193 mAh / g, a first discharge capacity of about 161 mAh / g, and an efficiency of about 83.6%, and the electrolyte of Composition 3, which has a first charge capacity of about 195 mAh / g, a first discharge capacity of about 162 mAh / g, and an efficiency of about 83.1%. Figures 8A-8C demonstrate that Compositions 1 and 3 exhibit similar first cycle capacities and efficiencies in both NMC611 / Gr and NMC811 / Gr full cells.

[0082] [Table 4]

[0083] The performance of NMC811 / Gr full cells using Compositions 1 and 3 was evaluated after conditioning cycles and the first formation cycle, as shown in Figures 8A-8C. The full cells were cycled at a rate of 0.33, with voltage windows of 4.2 V and 2.7 V for charge and discharge, respectively. The cells using the Composition 1 electrolyte were found to exhibit improved capacity retention values ​​after 500 cycles compared to the cells using the Composition 3 electrolyte, with the capacity retention at that time being approximately 88.5% for the Composition 1 electrolyte and 84.7% for the Composition 3 electrolyte.

[0084] The discharge capacity retention rate of the NMC622 / Gr full cell using the electrolyte of Composition 1 after the conditioning cycle and the first formation cycle is shown in Figure 9A, and the charge capacity retention rate is shown in Figure 9B. The charge capacity retention rates of Figures 9A and 9B are shown in Table 5.

[0085] [Table 5]

[0086] Conditioning cycle and first formation of NMC622 / Gr full cell using electrolyte of composition 3 The discharge capacity retention rate after the cycle is shown in Figure 10A, and the charge capacity retention rate is shown in Figure 10B. The charge capacity retention rates of Figures 10A and 10B are shown in Table 6.

[0087] [Table 6]

[0088] 9A to 10B and Tables 5 and 6 clearly show that electrolyte compositions 1 and 3 of NMC622 / Gr full cells exhibit similar behaviors in charge and discharge capacity retention as a function of various C-rates, such that the retention decreases with increasing C-rate, and composition 3 exhibits improved charge capacity retention than composition 1 at C-rates above 1C.

[0089] While specific embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications may be made in the systems and methods described herein without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or improvements as fall within the scope and spirit of the present disclosure. Accordingly, the scope of the present invention is defined solely by reference to the appended claims.

[0090] It should be understood that features, materials, properties, or groups described in connection with a particular aspect, embodiment, or example may also be applied to any other aspect, embodiment, or example described in this section or elsewhere in this specification, unless incompatible. All features disclosed herein (including the accompanying claims, abstract, and drawings), and / or all steps of methods or processes so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. Protection is not limited to the details of the foregoing embodiments. Protection extends to any new or novel combination of features disclosed herein (including the accompanying claims, abstract, and drawings), or any new or novel combination of method or process steps.

[0091] Furthermore, certain features that are described in this disclosure in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation may also be implemented separately in multiple implementations or in any suitable subcombination. Furthermore, although features are described above as acting in a particular combination, one or more features from a claimed combination may, in some cases, be deleted from the combination, and the combination may be claimed as a subcombination or a variation of the subcombination.

[0092] Furthermore, although operations may be illustrated in the figures or described in the specification in a particular order, such operations need not be performed in the particular order or sequential order shown, or even all of the operations, to achieve desirable results. can be incorporated into the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously with, or between any of the described operations. Furthermore, in other implementations, operations can be rearranged or reordered. Those skilled in the art will understand that in some embodiments, the actual steps performed in the illustrated and / or disclosed processes may differ from those shown in the figures. Depending on the embodiment, certain steps described above may be eliminated, and other steps may be added. Furthermore, the features and attributes of the specific embodiments disclosed above can be combined in different ways to form additional embodiments, all of which are within the scope of the present disclosure. Also, the separation of various system components in the above implementations should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated into a single product or packaged into multiple products. For example, any of the components of the energy storage systems described herein can be provided separately or integrated together (e.g., packaged or attached together) to form an energy storage system.

[0093] For purposes of this disclosure, certain aspects, advantages, and novel features have been described herein. Not necessarily all such advantages are achieved in accordance with a particular embodiment. Thus, for example, one skilled in the art will recognize that the present disclosure may be embodied or carried out in a manner that achieves one advantage or group of advantages taught herein, without necessarily achieving other advantages that may be taught or suggested herein.

[0094] Conditional language such as "can," "could," "could," and "might" is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not, unless otherwise specified or understood within the context in which it is used. Thus, such conditional language generally does not imply that the features, elements, and / or steps are required in one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or steps are included in or performed in a particular embodiment, with or without user input or direction.

[0095] Conjunctions such as "at least one of X, Y, and Z," unless otherwise specified, are understood apart from the context in which they are commonly used to convey items, terms, etc., and any of X, Y, or Z is the same. Thus, such conjunctions are not generally intended to suggest that a particular embodiment requires the presence of at least one X, at least one Y, and at least one Z.

[0096] As used herein, terms indicating degree, such as "approximately," "about," "roughly," and "substantially," refer to a value, amount, or characteristic that is close to a stated value, amount, or characteristic, yet performs a desired function or achieves a desired result. For example, the terms "approximately," "about," "roughly," and "substantially" can indicate less than 10%, less than 5%, less than 1%, and less than 0.1% of the stated amount, depending on the expected function or result.

[0097] The scope of the present disclosure is not intended to be limited by the specific disclosure of preferred embodiments in this section or elsewhere in this specification, but may be defined by the claims presented in this section or elsewhere in this specification, or presented in the future. Claim language should be interpreted broadly based on the language used in the claims, and not limited to the examples set forth herein, or that examples should be construed as non-limiting during prosecution of an application.

Claims

1. a cathode having a cathode active material; an anode having an anode active material; a separator between the cathode and the anode; an electrolyte having a composition of a lithium salt and a non-aqueous electrolyte solvent; The non-aqueous electrolyte solvent composition includes ethylene carbonate (EC) and dimethyl carbonate (DMC), The volume ratio of EC to DMC is 1:2 to 1:4, at least one of the cathode and the anode is substantially free of solvent residue; The energy storage device, wherein the cathode active material comprises a lithium transition metal oxide.

2. 2. The energy storage device of claim 1, wherein the non-aqueous electrolyte solvent composition comprises EC and DMC in a volume ratio of 1:

3.

3. 2. The energy storage device of claim 1, wherein the non-aqueous electrolyte solvent composition comprises EC and DMC in a volume ratio of 1:

4.

4. 10. The energy storage device of claim 1, wherein the non-aqueous electrolyte solvent composition includes an additional solvent selected from at least one of ethyl methyl carbonate (EMC) and propylene carbonate (PC).

5. 5. The energy storage device according to claim 4, wherein the non-aqueous electrolyte solvent composition has a volume ratio of EC to EMC of 1:0.5 to 1:

2.

6. 5. The energy storage device of claim 4, wherein the non-aqueous electrolyte solvent has a composition of EC, EMC, and DMC in a volume ratio of 1:0.5:

3.

7. 5. The energy storage device of claim 4, wherein the non-aqueous electrolyte solvent composition comprises EC and PC in a volume ratio of 1:0.

02.

8. 5. The energy storage device according to claim 4, wherein the non-aqueous electrolyte solvent composition has a volume ratio of EC to EMC of 1:2 to 1:

4.

9. 5. The energy storage device of claim 4, wherein the non-aqueous electrolyte solvent composition has a volume ratio of EC to EMC of 1:2.

4.

10. 5. The energy storage device of claim 4, wherein the non-aqueous electrolyte solvent composition has a volume ratio of EC to EMC of 1:

4.

11. The energy storage device of claim 1 , wherein the anode active material comprises natural graphite.

12. The energy storage device according to any one of claims 1 to 10, wherein the anode active material comprises surface-modified artificial graphite.

13. The energy storage device according to any one of claims 1 to 10, wherein the anode active material includes flaky artificial graphite.

14. 10. The energy storage device of claim 1, wherein the cathode active material comprises layered lithium nickel manganese cobalt oxide (NMC).

15. 2. The energy storage device of claim 1, wherein the lithium salt is LiPF.

16. A method for manufacturing the energy storage device according to any one of claims 1 to 15, comprising the steps of: the cathode, the anode, the separator, and the electrolyte are disposed within a housing; The method for manufacturing an energy storage device, wherein the separator is disposed between the cathode and the anode.

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