Graphite compositions and uses in battery technology

Abstract

The present disclosure relates to a composition comprising at least one 2 The carbonaceous particulate material is composed of synthetic graphite particles having a BET specific surface area (SSA) of 0.0447 Å / g and further comprising about 5% to about 75% (w / w) of at least one carbonaceous material coated with non-graphite carbon and having a surface area equal to or less than 8 m 2 Carbonaceous particulate materials composed of natural graphite particles with a BET SSA of 0.1% / g. Given the generally favorable electrochemical properties of such compositions, particularly for automotive and energy storage applications, they are particularly suitable for use as active materials for negative electrodes in, for example, lithium-ion batteries. The present disclosure also relates to the use of the non-graphitic carbon-coated natural graphite particles for preparing compositions suitable for use as active materials in, for example, negative electrodes of lithium-ion batteries. The non-graphitic carbon-coated natural graphite particles described herein are also suitable for use as carbonaceous additives to improve the energy density and charge rate performance of, for example, lithium-ion batteries while maintaining the power density of the battery, compared to batteries using negative electrodes without carbonaceous additives.

Description

Technical Field

[0001] The present disclosure relates to a composition comprising at least one 2 / g of a carbonaceous particulate material composed of synthetic graphite particles having a BET specific surface area (SSA) of about 1000 nm and further comprising about 5% to about 75% (w / w) of at least one carbonaceous material coated with non-graphite carbon and having a surface area equal to or less than 8 m 2 The carbonaceous particulate material is composed of natural graphite particles with a BET SSA of 0.05 wt % to 0.01 wt % of 10 ...

[0002] The present disclosure also relates to the use of the non-graphitic carbon-coated natural graphite particles for preparing a composition suitable for use as an active material in, for example, a negative electrode of a lithium-ion battery. The non-graphitic carbon-coated natural graphite particles described herein are also suitable for use as a carbonaceous additive to improve the energy density and charge rate performance of, for example, a lithium-ion battery while maintaining the battery power density compared to a battery using a negative electrode without a carbonaceous additive. Background Art

[0003] Lithium-ion batteries have become the battery technology of choice for consumer electronics such as laptop computers, smartphones, camcorders, and digital cameras. Among the advantages of lithium-ion battery systems compared to other battery chemistries are high energy density and specific energy, as well as high power performance due to an average cell voltage of approximately 3.5V and light overall electrode materials. The energy density of lithium-ion batteries has increased significantly over the past 25 years, since Sony introduced the first lithium-ion battery in 1991. This development has been driven in particular by the trend toward miniaturization of electronic devices, which has led to increased energy consumption and the need to reduce the size of accumulators and increase the capacity of electrochemical cells.

[0004] In recent years, lithium-ion batteries have also been considered for use in automotive applications such as hybrid, plug-in and all-electric vehicles, and for use in energy storage systems when integrated into power grids, for example, to buffer peak power consumption in the grid and to integrate often variable renewable energy generation such as wind and solar power.

[0005] Because batteries used in energy storage applications are mostly stationary, battery size and weight are less important than in other applications, such as mobile ones. On the other hand, battery durability and the number of charge and discharge cycles with a given capacity retention are important parameters in these applications. This, coupled with ensuring the highest level of battery safety, is a crucial prerequisite for the expansion of lithium-ion battery technology into all desired applications.

[0006] For automotive applications, the energy per unit volume of the battery (battery capacity or energy density) and the energy per unit weight of the battery (specific energy) play an important role in improving the limited driving range, which remains a major obstacle for electric vehicles. At the same time, for reasons of convenience and the possibility of reducing battery capacity, especially since the automotive industry, electricity suppliers and end users of such batteries require significantly longer service lives, the battery's charging speed as well as cycling stability and durability are more important for such applications than for consumer electronics batteries.

[0007] A key component influencing the electrochemical performance of lithium-ion batteries is the negative electrode (anode). In many lithium-ion batteries, the anode contains a carbonaceous material, such as graphite, as the electrochemically active material. Since carbon materials participate in the electrochemical redox processes occurring at the electrode by lithium intercalation and deintercalation during charging and discharging, respectively, the properties of the carbonaceous material are expected to play a significant role in the battery's performance characteristics. It is generally accepted in the art that graphite anodes have limitations in charge acceptance, which is the primary reason for the limited charging speed, a crucial requirement, particularly for automotive lithium-ion batteries.

[0008] In practice, lithium-ion batteries for automotive applications should offer high energy density, enabling a long driving range of at least 300 km (or more). Furthermore, these batteries should be highly durable, requiring manufacturers to offer a lifetime guarantee of up to 10 years (which the industry considers to correspond to the lifespan of the vehicle).

[0009] For example, battery power density should ideally be high enough to achieve 80% capacity retention after 20 min of discharge and a charging speed of about 20 min to reach 80% state of charge.

[0010] At the cell level, these desired properties translate into the following requirements for the anode: a high reversible capacity greater than about 350 mAh / g and a first-cycle Coulombic efficiency greater than about 92%. In addition, a suitable anode should exhibit high cycling stability, with a capacity retention of at least about 80% after 3000 cycles, as well as high charge acceptance and discharge capabilities at high C rates.

[0011] In recent years, specialty synthetic graphites have become active materials for electrode manufacturing, replacing natural graphite-based products because they generally have better cycling performance and low swelling during electrochemical lithium insertion, resulting in better cycling performance compared to natural graphite-based electrodes. However, achieving good battery durability while maximizing power and energy is quite difficult. Even graphites with high reversible capacity and high first-cycle efficiency often do not cycle well and often have low charge acceptance and discharge performance.

[0012] Therefore, while concurrent improvements in all major battery parameters such as energy density, power density, durability, and safety would be desirable, improvements in one parameter often negatively impact other battery parameters. For example, energy density cannot usually be increased without sacrificing power density, safety, or durability, and vice versa. Consequently, in the design and engineering of lithium-ion batteries, technicians often must accept trade-offs between various battery parameters.

[0013] Attempts to solve the problems observed with given graphite active electrode materials have been described in the art, including the use of mixtures of different graphite materials to provide graphite compositions that exhibit overall advantageous properties as electrode active materials. For example, WO 2014 / 024473 A1 (Showa Denko KK) describes a graphite mixture as a negative electrode active material comprising a combination of spherical synthetic graphite and spherical natural graphite. US 8,728,668 (Nippon Carbon Co., Ltd.) also describes a graphite mixture comprising three different graphites, the different graphites including synthetic graphite and natural graphite, differing in hardness and shape. EP 2 602 851 B1 similarly describes the use of a graphite mixture comprising artificial (synthetic) and natural graphite for preparing a negative electrode for a lithium ion battery.

[0014] Therefore, one object is to provide improved graphite compositions suitable for use as active materials, for example, in negative electrodes of lithium-ion batteries. Specifically, there is an ongoing need in the art for carbonaceous materials having beneficial properties when used as active materials in negative electrodes of lithium-ion batteries for automotive applications (e.g., electric vehicles) or energy storage applications. In particular, in such applications, it is desirable to increase charging speed, energy density, and charge retention without compromising cycling stability and durability. Summary of the Invention

[0015] The present inventors have surprisingly discovered that the addition of non-graphitic (e.g., amorphous) carbon-coated natural graphite particulate material to a composition comprising synthetic graphite particles (which are typically used as active material in negative electrodes, particularly for lithium-ion batteries) results in unexpected improvements in the fast charging performance of the battery without negatively impacting other relevant functional characteristics of the battery.

[0016] Specifically, it was found that adding the non-graphite carbon-coated natural graphite to the active material composition for the negative electrode improved the capacity retention of the electrode during the charging process. In addition to the higher charging speeds observed, the compositions described herein produce high energy density electrodes characterized by increased reversible capacity without significantly reducing cycling stability. It was also found that at the same binder content in the electrode, the mechanical stability ("peel strength") of the electrode was also improved, resulting in better processability during the electrode manufacturing process.

[0017] Thus, in a first aspect, the present disclosure relates to a composition comprising at least one 2 A carbonaceous particulate material consisting of synthetic graphite particles ("SG") having a BET SSA of 8 m / g and at least one carbonaceous particulate material consisting of particles coated with non-graphite carbon ("cNG") having a BET SSA of 8 m / g or less. 2 The carbonaceous particulate material is composed of natural graphite particles with a BET SSA of 0.1% / g. The content of the CNG particles in such a composition is generally about 5 wt% to about 75 wt%, or about 10 wt% to about 70 wt%, or about 15 wt% to about 65 wt%, based on the total weight of the composition.

[0018] In some cases, the composition may also include further additives, such as other carbonaceous materials and / or polymeric binders.

[0019] Another aspect of the present disclosure relates to a slurry in which particles of the composition are dispersed in a liquid, such as water.Such a slurry is typically used when preparing, for example, a (negative) electrode of a lithium-ion battery.

[0020] Yet another aspect of the present disclosure relates to a process for preparing the composition described herein, wherein the process comprises mixing synthetic graphite ("SG") as defined herein with natural graphite particles coated with non-graphitic carbon ("cNG") as described herein. This mixing can optionally be carried out in the presence of a liquid / solvent such as water or a water-based solvent composition (e.g., a water / alcohol mixture).

[0021] The use of natural graphite coated with non-graphitic carbon ("cNG") as described herein to prepare a composition suitable for use as an active material in a negative electrode represents another aspect of the present disclosure.

[0022] In a related aspect, the present disclosure also relates to the use of natural graphite coated with non-graphitic carbon ("cNG") as described herein as a carbonaceous additive to improve the energy density and charge rate performance of lithium-ion batteries while maintaining the battery power density compared to batteries employing anodes without carbonaceous additives.

[0023] A further aspect relates to the use of a composition as described herein for preparing a negative electrode for a lithium-ion battery. Such a lithium-ion battery can be suitable for use in, for example, electric vehicles, hybrid electric vehicles (HEVs), or energy storage batteries.

[0024] Electrodes comprising the compositions described herein as active material therefore represent another aspect of the present disclosure.

[0025] Finally, the present disclosure relates to lithium-ion batteries comprising the composition as described herein as the active material in the negative electrode of the battery, and to electric vehicles, hybrid electric vehicles or energy storage batteries comprising such lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 SEM images of a representative coated natural graphite reinforcement material used in the present disclosure are shown at two different magnifications.

[0027] Figure 2 Depicted are the charge retention values ​​at 2C in a button cell test, depending on the cNG / SG ratio in the composition used as active material in the negative electrode.

[0028] Figure 3 The charge retention values ​​at 2C of different synthetic graphites with a fixed 10 wt% addition of cNG enhancer-1 in coin cell tests are plotted.

[0029] Figure 4 Plotted are the CC charge rates of 3C, 5C, and 7C in pouch cell tests for two different synthetic graphites with a fixed 10 wt% addition of cNG reinforcer-1 (A: SG2 + 10% cNG reinforcer-1, B: SG4 + 10% cNG reinforcer-1).

[0030] Figure 5 The electrode peel strength of electrodes made from compositions with different cNG contents ranging from 0, 20%, 30%, 40% and 100% cNG Enhancer-3 is shown. DETAILED DESCRIPTION

[0031] The present inventors have discovered that adding carefully selected, typically spherical, highly crystalline natural graphites coated with a layer of non-graphitic (e.g., amorphous) carbon (hereinafter referred to as "cNG") to compositions containing synthetic graphite, commonly used as an active material in negative electrodes (anode) of lithium-ion batteries, can surprisingly improve the performance characteristics of the battery. Specifically, it has been found that batteries containing such compositions including cNG as the active anode material can achieve higher charging rates and increased electrode reversible capacity without significantly reducing the cycling stability of the battery. In addition, such compositions also generally improve the mechanical stability of the electrode.

[0032] Accordingly, a first aspect of the present disclosure relates to a composition comprising:

[0033] At least one of which has a diameter equal to or less than 4m 2 a carbonaceous particulate material composed of synthetic graphite particles ("SG") having a BET SSA of 0.0543 W / g; and

[0034] At least one of the following materials is coated with non-graphite carbon ("cNG") and has a thickness equal to or less than 8 m 2 / g of carbonaceous particulate material composed of natural graphite particles having a BET SSA;

[0035] The content of the cNG particles is about 5% to about 75% (w / w, i.e., cNG weight / total composition weight). In some embodiments, the content of the cNG particles is about 10% to about 70% (w / w).

[0036] The term "about," when used herein in the context of a parameter or value, encompasses a deviation of + / - 10% of the given value unless otherwise stated.

[0037] The synthetic graphite present in the composition can be any synthetic graphite suitable for use as an active material in a negative electrode. Thus, in some cases, the synthetic graphite particles in the composition have, in addition to having a particle size of about 4 μm or less, 2 In addition to the BET SSA of 100 g / g, further characterization may be performed by one or more of the following parameters (ie, alternatively or additionally).

[0038] In certain embodiments, the synthetic graphite particles may also be characterized as having a D 50 In some embodiments, the PSD D 50 The value is about 10 μm to about 25 μm, or about 10 μm to about 20 μm. 90 Values ​​are typically in the range of about 20 μm to about 40 μm.

[0039] In some embodiments, the synthetic graphite particles are further characterized by an interlayer distance c / 2 of about 0.3354 nm to about 0.3370 nm.

[0040] In certain embodiments, the synthetic graphite particles may have a particle size of about 0.5 μm. 2 / g-about 4m 2 / g, or about 1m 2 / g-about 3m 2 / g, or about 1m 2 / g-about 2m 2 / g of BET SSA.

[0041] Alternatively or additionally, in certain embodiments, the synthetic graphite particles may be characterized by a particle size of at least about 2.22 g / cm 3 , or at least about 2.23 g / cm 3 , or at least about 2.24 g / cm 3 Density of xylene.

[0042] In some embodiments, the synthetic graphite particles have a particle size of at least about 0.8 g / cm 3 ; or at least about 0.9 g / cm 3 , or at least about 0.95 g / cm 3 The tap density (tap density) of 1.5 % (after 400 taps).

[0043] In certain embodiments, the synthetic graphite particles may also be characterized by a ratio of the crystalline

[004] to

[110] reflection intensities ("OI") for a pressed electrode sheet comprising the graphite particles of less than about 50, or less than about 45, or less than about 40, or less than about 35, or less than about 30.

[0044] In some embodiments, the synthetic graphite particles may also be characterized as having a modified surface. Surface modification of graphite particles is generally known in the art and includes, but is not limited to, surface oxidation (generally making the particles more hydrophilic), or more commonly, non-graphitic coatings such as amorphous carbon, as described in more detail below with respect to the coating of the second component of the composition (i.e., the coated natural graphite).

[0045] Thus, in certain embodiments, the synthetic graphite particles comprise a non-graphitic, optionally amorphous carbon coating, preferably comprising less than about 5 wt%, or less than about 2%, or less than about 1% by weight of the total weight of the synthetic graphite particles.

[0046] In addition, in some embodiments, the synthetic graphite particles can be formed from aggregated smaller particles. In some embodiments, the aggregated particles can be additionally coated, for example, by one of the coating methods described below for coating natural graphite particles. Graphite made from aggregated particles is generally characterized by high isotropy.

[0047] Synthetic graphite particles having such properties can be prepared by methods known in the art or can even be obtained commercially. Suitable synthetic graphite particles, for example, are often sold specifically for use as negative electrode active materials.

[0048] The second component of the compositions described herein, namely the non-graphitic carbon-coated natural graphite particles, serves as an "enhancer" or "charge accelerator" for certain performance properties of electrodes in, for example, lithium-ion batteries, particularly higher charge rates, higher energy density, and increased reversible capacity without negatively impacting cycling stability.

[0049] The non-graphite natural graphite (cNG) of the composition may optionally be further characterized by one or more of the following parameters.

[0050] In certain embodiments, the non-graphite natural graphite particles are further characterized by having a D 50 In some embodiments, the PSD D 50 The value is from about 7 μm to about 15 μm, or from about 10 μm to about 15 μm.

[0051] Alternatively or additionally, the D of the cNG particles 90 The value may be less than about 40 μm, or less than about 35 μm, or less than about 30 μm. In some embodiments, the D 90 The value is about 20 μm to about 40 μm, or about 25 μm to about 35 μm, or about 25 μm to about 30 μm. It is generally believed that since even a small amount of large CNG particles of the composition is detrimental to the performance characteristics of the negative electrode, in a preferred embodiment, the D value of the CNG particles is about 20 μm to about 40 μm, or about 25 μm to about 35 μm, or about 25 μm to about 30 μm. 99 The value is less than about 45 μm, or less than about 40 μm.

[0052] As mentioned above, the BET SSA of the CNG particles in the composition is generally below 8 m 2 However, it is preferred that the BET SSA of the cNG particles be about 1.5 m 2 / g-about 6m 2 / g, or about 2.5m 2 / g-about 6m 2 / g, or about 3.5m 2 / g-about 5.5m 2 / g.

[0053] The natural graphite particles of the coating preferably have a high degree of crystallinity.Thus, in certain embodiments, alternatively or additionally, the cNG particles may be further characterized by an interlayer distance c / 2 of less than about 0.3357 nm, or less than about 0.3356 nm, or less than about 0.3355 nm.

[0054] In some embodiments, the cNG particles may be further characterized by a crystalline L of at least about 90 nm, or at least about 100 nm, or at least about 105 nm. cValue (this is measured by XRD). Preferably the crystallization L of the cNG particles c The value is from about 90 nm to about 200 nm, or from about 100 nm to about 180 nm, or from about 100 nm to about 150 nm.

[0055] Furthermore, the cNG particles should preferably have a spherical or nearly spherical shape, which can be achieved, for example, by grinding and / or autogenous surface treatment as is generally known in the art, see, for example, the autogenous grinding method described in WO 01 / 38220 (Timcal AG). Thus, alternatively or additionally, the cNG particles can be further characterized by a high sphericity (S), expressed as a Q3 (S=0.8) value of about 30% or less, or less than about 25%, less than about 30%, less than about 20% by weight, or less than about 15%, or less than about 10%. Sphericity (S) is obtained as the ratio of the circumference of the equivalent circle to the actual circumference (see the Methods section below for details on how to determine this parameter).

[0056] The coating on natural graphite particles is composed of non-graphitic carbon. Non-graphitic carbon is characterized by a two-dimensional, long-range order of carbon atoms in a planar hexagonal network, but lacks any measurable crystalline order in a third direction (the c-direction), other than more or less parallel stacking. Carbon deposited on the particle surface by pyrolysis is an example of non-graphitic carbon. Because there is no long-range order in any dimension, this type of carbon is also commonly referred to as amorphous carbon.

[0057] Graphite particles coated with non-graphitic / amorphous carbon therefore exhibit lower crystallinity on the particle surface compared to the crystallinity of the core. Since the laser used for Raman spectroscopy can only penetrate the upper surface layer of the particle, Raman spectroscopy represents a useful method for distinguishing coated or otherwise surface-modified carbon particles from uncoated / unmodified carbon particles.

[0058] Thus, in certain embodiments, alternatively or additionally, the natural graphite particles of the non-graphitic carbon coating may be further characterized by an I of at least about 0.2, or at least about 0.3, or at least about 0.4, or at least about 0.5, or at least about 0.6, and typically from about 0.3 to about 1.5, or from about 0.4 to about 1.3, or from about 0.5 to about 1.2, when measured using a laser having an excitation wavelength of 632.8 nm. D / I G Ratio (R(I D / I G )).

[0059] Generally speaking, Raman R(I D / I GThe value of R(I) depends on the nature (and thus the ratio) of the starting natural graphite material before coating on the one hand, and on the nature and thickness of the coating with non-graphitic carbon on the other hand, since amorphous carbon on the surface increases the intensity of the D band over the G band (compared to graphitic carbon). For example, the R(I) of the CVD-coated natural graphite particles used in the working examples is D / I G ) values ​​of 0.7-1.1, while uncoated crystalline graphite (whether natural or synthetic) is usually characterized by R(I D / I G ) values ​​are much lower than 0.2, and are usually lower than 0.15. Resin or pitch-coated graphite usually has R(I D / I G ) values ​​below 0.5 or 0.4 are generally preferred because such coatings tend to have fewer defects than CVD-applied coatings.

[0060] In some embodiments, the cNG particles, alone or in combination, can be further characterized by a particle size of at least about 0.8 g / cm 3 , or at least about 0.85 g / cm 3 , or at least about 0.9 g / cm 3 , or at least about 0.95 g / cm 3 The tap density after 400 taps.

[0061] The natural graphite particles used in the coatings for batteries are typically of high purity. Thus, in many embodiments, the cNG particles can be further characterized by a moisture content of less than about 0.05 wt%, or less than 0.03 wt%. Similarly, the cNG particles can have an ash content of less than about 0.05 wt%, or less than 0.03 wt%. The iron (Fe) content is preferably less than about 50 ppm, or less than 40 ppm, or less than 35 ppm (by XRF).

[0062] With respect to the non-graphite coating, in some embodiments, the cNG particles may alternatively or additionally be further characterized by the thickness of the coating, which may be expressed as a weight percentage of the total weight of each particle. Thus, in certain embodiments, the non-graphite carbon coating of the cNG particles of the compositions described herein comprises from about 0.5% to about 20% (w / w), or from about 0.5% to about 10% (w / w), or from about 1% to about 5% (w / w), of the total weight of the cNG particles.

[0063] The coating of natural graphite particles can generally be applied by any suitable means known in the art. Coating techniques can be divided into two categories: one in which non-graphitic / amorphous carbon is deposited directly onto the surface of graphite (or other carbonaceous particles of such material), and the other in which the particles are first coated with a carbon-containing precursor (typically an organic compound having a high carbon content) and then converted to non-graphitic carbon by heating the carbon precursor-coated particles to a temperature of at least about 500 to about 1200° C. in an inert atmosphere ("carbonization" or "calcination").

[0064] Examples of direct coatings include firstly chemical vapor deposition (CVD), but also physical vapor deposition (PVD) or plasma spraying, all of which are generally known to those skilled in the art. The second category includes pitch-coatings (wherein the carbon-containing precursor is petroleum-based pitch or coal tar pitch), as well as coatings with other organic precursor molecules, for example, amphiphilic surfactants such as PEO-PPO-PEO block copolymers, polyethylene glycol ethers, alkyl-aryl polyethylene glycol ethers, aryl-ethyl-phenyl polyethylene glycol ethers, aryl polyethylene glycol ethers, carboxylic acid polyethylene glycol ester nonionic surfactants, alkyl polyoxyethylene ethers, aryl polyoxyethylene ethers, phenolic varnish-based resins such as nonylphenol phenolic varnish ethoxylates, polystyrene methacrylate copolymers, polyacrylates, polyacrylate copolymers; alkyl-, phenyl- or polyalkylphenyl sulfonates, sulfated lignin, lignin sulfonates or mixtures thereof, as, for example, described in WO 2015 / 158741.

[0065] Thus, in some embodiments, the non-graphitic carbon coating of the cNG particles is obtainable by a method selected from CVD coating, PVD coating, plasma coating, pitch-coating, or amphiphilic surfactant coating, e.g., using one of the surfactants listed above.

[0066] Preferably, the non-graphite carbon coating of the cNG particles can be obtained by chemical vapor deposition (CVD). As mentioned above, such CVD-coated natural graphite particles will exhibit an R(I) of at least about 0.4, or at least about 0.5, or at least about 0.6. D / I G )value.

[0067] For example, the non-graphite carbon coating can be obtained by chemical vapor deposition of a natural graphite particle starting material using a hydrocarbon gas such as acetylene or propylene, typically mixed with an inert carrier gas such as nitrogen or argon, at a temperature of 500-1200° C., for a treatment time typically of 3-120 minutes, for example, in a rotary kiln or fluidized bed. Again, it will be understood that certain modifications to the process may be necessary (e.g., length of exposure to the hydrocarbon gas, choice of hydrocarbon gas and starting material, etc.) in order to obtain a material exhibiting the desired parameters described above.

[0068] Thus, in certain embodiments, the non-graphite carbon coating of the cNG particles can be obtained by chemical vapor deposition (CVD), optionally by subjecting a natural graphite particle starting material to a CVD treatment using a hydrocarbon gas at a temperature of 500-1200° C., typically with a treatment time of about 3 to about 120 minutes.

[0069] In certain embodiments, the cNG particles of the composition may be characterized by having a hydrophilic non-graphite, such as an amorphous carbon coating. Such a hydrophilic non-graphite carbon coating can be, for example, obtained by first coating natural graphite particles with a non-graphite carbon layer (e.g., by CVD) and then exposing the coated particles to an oxygen-containing gas atmosphere under controlled conditions, as described in PCT / EP2015 / 066212, which is incorporated herein by reference in its entirety. Exposure to an oxygen-containing atmosphere will increase the hydrophilicity of the graphite particles and, for convenience, is sometimes referred to herein as "activation" or "surface oxidation." Therefore, the carbon coating of the hydrophilic surface-modified carbonaceous particulate material is, in certain embodiments, composed of (partially) oxidized amorphous carbon.

[0070] In some of these embodiments, the at least one hydrophilic surface-modified carbonaceous particulate material can be further characterized by increased wettability compared to non-oxidized (ie, non-activated) coated particles.

[0071] Suitable methods and the resulting hydrophilic surface-modified (coated) carbonaceous particles are, for example, described in detail in WO 2016 / 008951 A1, as previously mentioned herein, the disclosure of which is incorporated herein by reference in its entirety.

[0072] In certain embodiments, the coated natural graphite particles are further characterized by a ratio of the crystalline

[004] to

[110] reflectance intensities ("OI") for a pressed electrode sheet comprising said graphite particles of greater than about 40, or greater than about 45, or greater than about 50, or greater than about 55, or greater than about 60, or greater than about 65, or greater than about 70, or greater than about 75, or greater than about 80, or greater than about 90, or greater than about 100. Details regarding the preparation of the electrode sheets used to determine this parameter are described in the Methods section below (see "Coin Cell Test Methods," "Electrode Preparation" section).

[0073] As noted above, the weight content of the cNG particles in the composition can vary significantly depending on the desired properties of the composition and the specifics of the graphite type selected, but improvements resulting from the addition of coated natural graphite particles have been observed when the cNG particles are present in an amount from about 5% to about 75%, or from about 5% to about 70%, by weight, based on the total weight of the composition (see Examples, Table 4).

[0074] In some embodiments, the weight content of the cNG particles is about 5% to about 65%, or preferably about 5% to about 60%, of the total weight of the composition.

[0075] In addition to the two graphite materials (coated natural graphite and synthetic graphite), the composition described in detail above herein may optionally further comprise at least one additional carbonaceous material as an additive. When present in the composition, the at least one carbonaceous additive is typically present in an amount of at most 20%, or at most 10%, or at most 7%, or at most 5% (w / w) of the total composition.

[0076] Suitable carbonaceous additives include, but are not limited to, conductive materials such as natural or synthetic graphite (in addition to the two main components of the composition), coke, flake graphite, graphene, few-layer graphene, graphite fiber, nanographite, graphitized coke fines, non-graphitic carbon (including hard carbon, carbon black, petroleum- or coal-based coke, glassy carbon, carbon nanotubes (including single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs)), fullerenes, carbon fibers, or mixtures of any of these materials. For example, in some embodiments, the composition may further comprise at least one carbonaceous additive selected from carbon black, carbon nanotubes, graphene, or a combination thereof.

[0077] It should be understood that the compositions described herein may, in some embodiments, also include more than one synthetic graphite (SG) component and / or coated natural graphite (cNG) component. Thus, it is possible to use, for example, two or three different coated natural graphite materials (i.e., differing in parameters within the limits defined herein), or to use two or three different types of synthetic graphite (within the limits defined herein) having different properties, or both.

[0078] In addition, since the composition is particularly suitable for preparing the negative electrode of a lithium-ion battery, in certain embodiments, the composition may further include a polymer binder material. Suitable polymer binder materials include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), carboxymethyl cellulose (CMC), polyacrylic acid and its derivatives, polyvinylidene fluoride (PVDF) or mixtures thereof, typically used in an amount of 1 wt% to 5 wt%.

[0079] The compositions can be further defined by their functional properties when used as active materials in lithium-ion battery anodes.

[0080] Thus, in certain embodiments, the composition can be further characterized by an electrode capacity of at least about 350 mAh / g, or at least about 352 mAh / g, or at least about 353 mAh / g, or at least about 354 mAh / g. Alternatively or additionally, when used as an active material in a negative electrode of a lithium-ion battery, the composition has a capacity retention at 2C (expressed as the ratio of the constant current charge capacity at 2C to the constant current charge capacity at 0.1C) of at least about 20%, or at least about 21%; or at least about 22%. Details on the measurement of this property are provided in the Methods section below ("Coin Cell Test Protocol").

[0081] In other embodiments, the composition, when used as an active material in a negative electrode of a lithium-ion battery, achieves a constant current (CC) charge rate at 3C of at least about 75% or at least about 80%; and / or a CC charge rate at 5C of at least about 60% or at least about 65%; and / or a CC charge rate at 7C of at least about 45% or at least about 50%. Details of the measurement of this property are also provided in the Methods section below (see "Pouch Cell Testing Protocol").

[0082] Alternatively or additionally, the compositions described herein may also be characterized in that they improve the electrochemical parameters of a battery comprising the composition as the active material in the negative electrode, compared to a battery in which the negative electrode is made solely of the synthetic graphite component of the composition (i.e., in the case of uncoated natural graphite particles).

[0083] For example, in some embodiments, the compositions described herein, when used as the active material in a negative electrode of a lithium-ion battery, can produce a relative increase in capacity retention at 2C of at least about 20%, or at least about 25%, or at least about 30%, compared to an electrode made with a corresponding composition of uncoated natural graphite particles (cNG).

[0084] Alternatively or additionally, the compositions described herein, when used as active material in a negative electrode of a lithium-ion battery, can produce the following relative increases in CC charge rate compared to electrodes made with corresponding compositions of uncoated natural graphite particles (cNG):

[0085] i) at least about 2% at 3C; and / or

[0086] ii) at least about 3% at 5°C; and / or

[0087] iii) at least about 10% at 7°C.

[0088] When the graphite compositions described herein are used to prepare negative electrodes, they are typically dispersed in a suitable (inert) liquid medium, such as water or a water / lower alcohol (e.g., ethanol) mixture. Therefore, another aspect of the present invention relates to a slurry or dispersion of the compositions described herein in a liquid. The liquid (or solvent, although the graphite does not dissolve in the "solvent" but is dispersed therein) is typically water or a water / alcohol mixture. Optionally, the slurry or dispersion may further comprise a surfactant to improve the stability of the dispersion.

[0089] Process for preparing the composition of the present disclosure

[0090] Yet another aspect of the present disclosure relates to a process for preparing a composition according to the present disclosure, comprising mixing synthetic graphite ("SG") as defined herein with natural graphite coated with non-graphitic carbon ("cNG") as defined herein, optionally in the presence of a liquid such as water or a water / alcohol mixture.

[0091] This process may also include the addition of one or more additives as described above, for example, a carbonaceous additive or a polymer binder. Optionally, a surfactant may also be added. When a solvent is used during the mixing process, the solvent may be optionally removed from the composition after the mixing step.

[0092] Uses of the composition

[0093] Because the compositions of the present disclosure provide a beneficial combination of properties as active materials in negative electrodes (e.g., lithium-ion batteries), the use of the compositions defined herein for preparing negative electrodes (e.g., for lithium-ion batteries) represents another aspect of the present invention. Such lithium-ion batteries are suitable, in some embodiments, for use in electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, or energy storage batteries.

[0094] Downstream products using the disclosed compositions

[0095] Electrodes, such as negative electrodes, comprising a composition as defined herein as an active material represent another aspect of the present disclosure. This includes electrodes wherein the negative electrode comprises less than 100% of the carbonaceous particulate material according to the present disclosure as the active material. In other words, negative electrodes comprising a mixture with other materials (graphite or other materials) are also considered an aspect of the present disclosure.

[0096] In another aspect, the present disclosure also relates to a lithium ion battery comprising a composition as defined herein as the active material in the negative electrode of the battery. Likewise, batteries wherein the negative electrode comprises a mixture with other carbonaceous particulate materials are also included in this aspect of the present disclosure.

[0097] Yet another aspect of the present disclosure relates to an electric vehicle, hybrid electric vehicle or plug-in hybrid electric vehicle or an energy storage battery comprising a lithium ion battery, wherein the lithium ion battery comprises a composition as defined herein as the active material in the negative electrode of the battery.

[0098] Other Uses

[0099] In another aspect, the present disclosure further relates to the use of natural graphite (cNG) coated with non-graphitic carbon as defined herein for preparing a carbonaceous composition suitable for use as an active material in a negative electrode. As mentioned above, such active material compositions typically comprise low surface area synthetic graphite, such as the synthetic graphite described in the present disclosure.

[0100] It has been discovered that coated natural graphite particles, as defined herein, act as "enhancers" / "charge accelerators" of certain electrochemical properties, such as increasing the energy density and charge rate performance of lithium-ion batteries while maintaining the battery's power density and durability. Good results have been achieved when the coated natural graphite particles comprise from about 5% to about 75%, or from about 10% to about 70%, or from about 15% to about 65%, of the total weight of the active material composition.

[0101] Thus, the use of natural graphite coated with non-graphitic carbon (cNG) as defined herein as a carbonaceous additive to improve the energy density and charge rate performance of lithium-ion batteries while maintaining the power density of the battery, compared to batteries without carbonaceous additives in the negative electrode, represents another aspect of the present disclosure.

[0102] Measurement method

[0103] Suitable methods for determining the various properties and parameters used to define the compositions and carbonaceous materials described herein are described in detail below.

[0104] Unless otherwise indicated, percentage (%) values ​​specified herein are by weight.

[0105] BET specific surface area, DFT micropore and mesopore volume and area

[0106] The method is based on the recording of adsorption isotherms of liquid nitrogen at 77 K in the range of p / p0 = 0.04-0.26. Nitrogen adsorption is carried out on a Quantachrome Autosorb-1. According to the protocol proposed by Brunauer, Emmet and Teller (Adsorption of Gases in Multimolecular Layers, J.Am.Chem.Soc., 1938, 60, 309-319), the monolayer capacity can be determined. Based on the cross-sectional area of ​​the nitrogen molecule, the monolayer capacity and the sample weight, the specific surface area can be calculated. The isotherms measured in the pressure range of p / p0 0.01-1 at 77 K can be processed by DFT calculations to evaluate the pore size distribution, micropore and mesopore volume and area.

[0107] References: Ravikovitch, P., Vishnyakov, A., Russo, R., Neimark, A., Langmuir 16 (2000) 2311-2320; Jagiello, J., Thommes, M., Carbon 42 (2004) 1227-1232.

[0108] Particle size distribution by laser diffraction

[0109] The presence of particles in a coherent light beam causes diffraction. The size of the diffraction pattern is related to the particle size. A parallel beam from a low-power laser illuminates a cell containing a sample suspended in water. The beam leaving the cell is focused by an optical system. The distribution of the light energy in the focal plane of this system is then analyzed. The electrical signal provided by the optical detector is converted into a particle size distribution by a computer. This method produces the ratio of the total volume of particles to the discrete number of size classes that make up the volume particle size distribution (PSD). This particle size distribution is usually represented by the value D 10 、D 50 and D 90 Definition, where 10% (by volume) of the particle population has a particle size below D 10 The size of the particle population is such that 50% (by volume) of the particle population has a particle size below D 50 The size of the particle size is less than D 90 The size of the value.

[0110] The particle size distribution data by laser diffraction cited herein were measured using a MALVERN Mastersizer S. To determine the PSD, a small sample of the carbon material was mixed with a few drops of a wetting agent, such as the nonionic surfactant Imbentin PAP / 6200, and a small amount of water. The sample prepared in this manner was introduced into the storage container of the device (MALVERN Mastersizer S) and subjected to ultrasonic treatment for 5 minutes at 100% intensity and a pump and stirrer speed set at 40%, before the measurement.

[0111] Reference: ISO 13320(2009) / ISO 14887

[0112] X-ray diffraction

[0113] XRD data were collected using a PANalytical X'PertPRO diffractometer coupled to a PANalytical X'Celerator detector. The diffractometer had the following characteristics, as shown in Table 1:

[0114] Table 1: Instrument data and measurement parameters

[0115]

[0116]

[0117] Data were analyzed using PANalytical X'Pert HighScore Plus software.

[0118] Interlayer distance c / 2

[0119] The interlayer distance c / 2 is determined by X-ray diffraction. The angular position of the peak maximum of the

[002] reflection curve is determined and the interlayer distance is calculated by applying the Bragg equation (Klug and Alexander, X-ray diffraction Procedures, John Wiley & Sons Inc., New York, London (1967)). To avoid problems such as the low absorption coefficient of carbon, instrument calibration and sample non-planarity, internal standard silicon powder is added to the sample and the graphite peak position is recalculated based on the position of the silicon peak. The graphite sample is mixed with silicon standard powder by adding a mixture of polyethylene glycol and ethanol. The obtained slurry is then applied to a glass plate by a blade with a spacing of 150 μm and dried.

[0120] Crystallite size L c

[0121] The crystallite size is determined by analyzing the

[002] diffraction curve and determining the half-peak width of the peak curve. As Scherrer (P.Scherrer, Nachrichten 2, 98 (1918) suggested that the broadening of the peak should be affected by the crystallite size. However, the broadening is also affected by other factors such as X-ray absorption, Lorentz polarization, and atomic scattering factors. Several methods have been proposed to account for these effects by using internal standard silicon and applying a correction function to the Scherrer equation. For the present disclosure, the method recommended by Iwashita (N. Iwashita, C. Rae Park, H. Fujimoto, M. Shiraishi and M. Inagaki, Carbon 42, 701-714 (2004)) was used. The sample preparation was the same as that for the c / 2 determination described above.

[0122] Crystal diffraction peak intensity ratio ("OI")

[0123] The OI values ​​represent the diffraction peak intensity ratios of the (004) and (110) reflections of a pressed electrode comprising the graphite composition as described herein as an active material (“I (004) / I (110) Pressed electrodes were prepared in the same manner as described below ("Button Cell Test Procedure").

[0124] Density of xylene

[0125] This analysis is based on the liquid exclusion principle defined in DIN 51 901. Approximately 2.5 g (accuracy 0.1 mg) of powder are weighed in a 25 mL pycnometer. Xylene is added under vacuum (15 Torr). After a few hours at atmospheric pressure, the pycnometer is adjusted and weighed. Density represents the ratio of mass to volume. The mass is given by the weight of the sample, while the volume is calculated by the weight difference of the xylene-filled pycnometer with and without the sample powder.

[0126] Reference: DIN 51 901

[0127] Tap density

[0128] Carefully pour 100g of dry graphite powder into a graduated cylinder. Then, secure the cylinder to an off-centre shaft-based tapping machine and tap 400 times. Read the volume and calculate the resulting density.

[0129] Reference: DIN-ISO 787-11

[0130] Dynamic image analysis

[0131] The sphericity and aspect ratio of the material particles can be obtained by an image analysis sensor, which is a combination of particle size and shape analysis. The experiments were carried out using a Sympatec QICPIC sensor and a MIXCEL dispersion unit. The material was made into a paste using water and a surfactant (liquid detergent). The instrument uses a high-speed camera (up to 500 fps) and a pulsed light source to capture clear back-illuminated images of the entrained particles. For an average of more than 500,000 measured particles, the measurement time typically varies from 30 to 60 seconds. To reproduce the measurement results, each sample was repeated 3 times. The software program determines all parameters of the particles.

[0132] Sphericity

[0133] Sphericity S is the circumference P of the equivalent circle (assuming the particle is a circle with a diameter such that it has the same area as the projected area of ​​the particle) EQPC and the actual perimeter P 实际 The value Q3(S=0.8) corresponds to the percentage of particles (by cumulative volume) whose sphericity is lower than S=0.8. Therefore, a small percentage indicates that the sample has highly spherical particles, because most of the particles in the sample have a sphericity greater than 0.8.

[0134] Raman spectroscopy

[0135] Raman analysis was performed using a LabRAM-ARAMIS Micro-Raman Spectrometer with a 632.8 nm HeNe LASER from HORIBA Scientific.

[0136] I D / I G The ratio ("R value") is based on the ratio of the intensities of the so-called D-band and G-band. These peaks are at 1350 cm -1 and 1580cm -1 It is measured at , and is a characteristic peak of carbon materials.

[0137] Fe content

[0138] The analysis was performed using a SDAR OES simultaneous emission spectrometer. Graphite powder was ground to a maximum particle size of 80 μm using a vibrating mill and then pressed into pellets. The sample was placed on the spectrometer's excitation stage under an argon atmosphere. The fully automated analysis then began.

[0139] Ash content

[0140] Ignite a low-walled ceramic crucible in a muffle furnace at 800°C and dry in a desiccator. Weigh 10 g of the dry powder sample (accuracy 0.1 mg) into the low-walled ceramic crucible. Combust the powder at 815°C to constant weight (at least 8 hours). The residue corresponds to the ash content. It is expressed as a percentage of the initial sample weight.

[0141] References: DIN 51903 and DIN 51701 (dividing process), ASTM C 561-91

[0142] Moisture content

[0143] Moisture content is tested according to Japanese standard JIS M8511. Briefly, a 10g ± 0.25g sample is weighed and dried at 107°C for two hours. The sample is then cooled in a desiccator. The weight difference is recorded to calculate the moisture content.

[0144] Peel strength test

[0145] The peel strength test was performed using an Instron. The test was performed as follows. A pressed electrode (1.6 g / cm 3 Place a 150 mm long x 35 mm wide double-sided tape on the test panel. Use a metal roller to ensure good adhesion of the tape to the panel.

[0146] Use the same method to fix the right end of the electrode to the tape. Then place the metal plate on 3343 Series device and attach the left end of the electrode to the test clip.

[0147] After aligning the electrode strip and the test clamp in the vertical direction, a 180° peeling was performed at a peeling speed of 100 mm / min to obtain the peel strength.

[0148] Electrochemical measurements:

[0149] Electrochemical measurements

[0150] A) Button Battery Test Solution

[0151] Electrode preparation

[0152] The electrode containing the coating natural graphite reinforcement can be prepared according to the following steps. The obtained electrode is used for button cell testing.

[0153] The synthetic graphite and reinforcing agent are weighed and placed in a closed container. The powders are then mixed at a low mixing speed for 5 minutes. The mixing process can be accomplished using various mixers used to produce electrode slurries for coating. For example, using a THINKY Mixer, mixing speed is 500 rpm.

[0154] A 1 wt% aqueous solution of carboxymethyl cellulose (CMC, or conductive carbon dispersion) was then added to the container. The container was then mixed at 2000 rpm for 5 minutes. Deionized water was added to the container. The container was then mixed again at 2000 rpm for 5 minutes. Finally, a 48.5 wt% styrene-butadiene rubber (SBR) suspension was added to the container. The container was subjected to a final mixing at 2000 rpm for 5 minutes, followed by degassing at 2200 rpm for 2 minutes.

[0155] The resulting slurry had a solids content of 46%. The weight ratio of the different components was graphite (SG + cNG reinforcement): CMC: binder = 97.5:1.5:1.5. The slurry was then applied to a 20 μm copper foil and subsequently dried at 80°C. The typical graphite loading was 8 mg / cm 2 For the button cell test, the electrode was pressed to 1.6 g / cm 3 density.

[0156] Button battery assembly

[0157] CR2032 coin cells were assembled to test their charge rate performance. A piece of lithium metal served as the counter and reference electrodes. The electrolyte consisted of 200 μl of 1 M LiPF6 EC / ECM / DMC (weight ratio 3 / 5 / 2). A Celgard 2500 separator was used.

[0158] Charging rate performance test

[0159] The coin cell was charged to 1.5 V at 2.0 C and then charged at a constant voltage until the current dropped to 0.01 C. The cell was then discharged at 0.1 C. The capacity retention at 2 C is the ratio of the constant current charge capacity at 2 C to that at 0.1 C.

[0160] Description of the Laminated Cell Test Protocol

[0161] Electrode preparation

[0162] In a typical run, electrodes containing a reinforcing agent were prepared according to the following steps. These electrodes were used for lamination testing.

[0163] For the negative electrode:

[0164] The synthetic graphite and reinforcing agent are weighed and placed in a mixer container. The powders are then mixed at a low mixing speed for 5 minutes. The mixing process can be accomplished using various mixers used to produce electrode slurries for coating. For example, a Primix 2P-03 mixer can be used at a mixing speed of 20 rpm.

[0165] A dispersion of 1 wt% CMC and 0.5 wt% carbon black (Imerys Cnergy C65) was added and mixed at 50 rpm for 30 minutes. Deionized water was added to adjust the solids content. The slurry was then mixed at 80 rpm for 30 minutes. Finally, a styrene-butadiene rubber (SBR, 48.5 wt%) suspension was added to the container. The slurry was stirred at 80 rpm for 30 minutes and then degassed at 20 rpm for 10 minutes. The final solids content was 49%.

[0166] The weight ratio of different components is graphite (SG+reinforcement agent): conductive carbon: CMC: binder = 97.5:0.5:1.0:1.5.

[0167] The resulting slurry was applied to copper foil using a roll-roll coater while drying at 80°C. The material loading was 5 mg / cm 2 The electrode material was pressed to 1.6 g / cm 3 density.

[0168] For the positive electrode

[0169] The positive electrode was prepared using the same mixer as the negative electrode. The final positive electrode slurry composition was lithium nickel cobalt manganese oxide: carbon black: binder = 96:1:3, with a solid content of 70%. The solvent used in the positive electrode preparation was N-methyl-2-pyrrolidone (NMP).

[0170] The slurry was then applied to aluminum foil using a roll-to-roll coater. The drying temperature was 120°C. The loading of the material was 10 mg / cm 2 The electrode material is pressed to 3.0g / cm 3 density.

[0171] Pouch battery charging performance test

[0172] The 30 mAh pouch cells were assembled in a dry room with a dew point below -40°C. The electrolyte was 1 M LiPF6 EC / EMC / DMC (each accounting for 1 / 3 by volume) and 1 wt% vinylene carbonate (VC).

[0173] The charging rate performance test is carried out as follows:

[0174] The battery was charged to 4.2V in constant current-constant voltage (CC-CV) mode. The battery was charged to 4.2V at nC constant current (0.2C, 0.5C, 1.0C, 2.0C, 3.0C, 5.0C, 7.0C), and then charged at 4.2V until the current dropped to 0.01C. The battery was discharged to 2.5V at 0.5C. The CC charge capacity ratio was calculated based on the following equation:

[0175]

[0176] Although various aspects of the disclosure have been generally described, it will be apparent to those skilled in the art that many modifications and variations are possible without departing from the spirit and scope of the disclosure.

[0177] Example

[0178] Example 1

[0179] Various compositions comprising synthetic graphite as defined herein and coated natural graphite were prepared and then used to prepare electrodes.

[0180] The physicochemical properties of the synthetic graphite used in the working examples are summarized in Table 2 below.

[0181] Table 2: Physicochemical properties of synthetic graphite (SG)

[0182] synthetic graphite BET SSA <![CDATA[PSD D 10 ]]> <![CDATA[PSD D 50 ]]> <![CDATA[PSD D 90 ]]> Tap density c / 2(nm) OI value of negative electrode SG1 1.7 8 17 34 0.94 0.3363 6.2 SG2 1.2 5 13 25 0.92 0.3359 40 SG3 1.3 7 15 28 1.09 0.3360 36 SG4 1.4 9 15 23 1.00 0.3358 7.1

[0183] The physicochemical properties of the coated natural graphite used in the working examples are summarized in Tables 3a and 3b below:

[0184] Table 3a: Physicochemical properties of coated natural graphite (cNG)

[0185]

[0186] *Parameters exceed the specifications of the cNG used in this disclosure

[0187] Table 3b: Other properties of coated natural graphite (cNG)

[0188]

[0189] The graphite compositions were mixed together as described above in the methods section. The slurry comprising the composition having SG and cNG was then used to prepare a negative electrode as described in more detail in Example 2.

[0190] Example 2

[0191] Electrodes containing synthetic graphite and coated natural graphite reinforcement were prepared according to the following steps.

[0192] Weigh X g of synthetic graphite and Y g of cNG reinforcement into a sealed container (X + Y = 35 g). The powders are then mixed at a low speed for 5 minutes. The mixing process can be accomplished with any mixer commonly used to produce copper foil coating slurries. In this case, a THINKY ARE-310 was used at a mixing speed of 500 rpm.

[0193] Then 35.9g of carboxymethyl cellulose (CMC, 1wt%) aqueous solution was added to the container. The container was then subjected to a mixing step at 2000rpm for 5 minutes. Then 6g of deionized water was added to the container and the mixture was again subjected to a mixing step at 2000rpm for 5 minutes.

[0194] Finally, 1.44 g of styrene butadiene rubber (SBR, 48.5 wt %) suspension was added to the container, and the resulting mixture was then subjected to a mixing step at 2000 rpm for 5 minutes and a degassing step at 2200 rpm for 2 minutes.

[0195] The resulting slurry had a solid content of 46 wt%. The slurry obtained by the described procedure was then applied to a 20 μm copper foil and dried at 80° C. The typical loading of graphite was 8 mg / cm 2 For the coin cell test, the electrodes were pressed to 1.6 g / cm 3 density.

[0196] Electrodes prepared in this manner were used for coin cell testing, as described in more detail below.

[0197] Example 3

[0198] The electrodes prepared according to Example 2 were used in button cell tests to determine the capacity retention at 2C (the ratio of the constant current charge capacity at 2C to the constant current charge capacity at 0.1C), as described in detail in the Methods section above (see Button Cell Test Method). The capacity retention experimental results for different synthetic graphites and different cNG enhancers / concentrations are shown in Figure 2. Figure 2 The results are shown in Table 4 below.

[0199] Table 4: Capacity retention at 2C of synthetic graphite electrodes with different concentrations of coated natural graphite reinforcement components

[0200] wt% of synthetic graphite (SG1) cNG enhancer Capacity retention rate at 2C (%) Electrode capacity (mAh / g) 100 - 15.5 342.1 95 Enhancer-1 21.7 345.0 90 Enhancer-1 22.6 346.2 80 Enhancer-1 23.8 346.7 80 Enhancer-2 25.9 353.7 80 Enhancer-3 27.3 353.2 80 Enhancer-4 30.6 354.6 80 Compare CNG 14.1 354.0 60 Enhancer-1 24.4 352.2 40 Enhancer-1 23.0 354.4 20 Enhancer-1 20.2 358.0 0 Enhancer-1 11.9 360.0 0 Compare CNG 10.1 356.7

[0201] Example 4

[0202] Different synthetic graphite materials were also investigated to evaluate the dependence of these results on the type and properties of the synthetic graphite in the composition. Figure 3 The results are shown in Table 5 below.

[0203] Table 5: Capacity retention at 2C for different synthetic graphites

[0204] Capacity retention rate at 2C (%) SG1 SG2 SG3 SG4 No additives 15.5 14.1 17.2 18.6 cNG enhancer-1 10wt% in electrode 22.6 17.8 21.6 23.2

[0205] Example 5

[0206] As described in more detail in the Methods section, the effect of cNG reinforcement materials on the charge rate performance of lithium-ion batteries was tested in pouch cells. Two synthetic graphites (SG1 and SG4) were used to prepare pouch cell electrodes and compared to a composition that also included 10 wt% cNG reinforcement material (Reinforcer-1).

[0207] After the pouch cells were prepared as described in the methods section above, the charge rate performance was tested by charging the cells to 4.2 V in constant current-constant voltage (CC-CV) mode. The cells were then discharged to 2.5 V at 0.5 C. The CC charge capacity ratio was calculated based on the following equation:

[0208]

[0209] The results for the four different compositions are summarized in Table 6 below and illustrated in Figure 6. Figure 4 (A compares SG1 with SG1+10 wt% cNG enhancer-1, B compares SG4 with SG4+10 wt% cNG enhancer-1).

[0210] Table 6: CC charge ratio improvement at high charge rates

[0211]

[0212] Example 6

[0213] Different amounts of cNG enhancer-3 (20 wt%-100 wt%) were added to SG1, and the electrodes were pressed to 1.6 g / cm under the same pressure of 9 kN. 3 density.

[0214] according to Figure 5 It can be seen that the addition of cNG-reinforcement agent-3 at a ratio of 20 wt % to 40 wt % significantly improves the peel strength of the electrode compared to that of the electrode made of SG1 alone.

Claims

1. A composition comprising: At least one of which has a diameter equal to or less than 4 m 2 / g BET SSA of synthetic graphite particles; and At least one of a plurality of carbon sheets coated with non-graphite carbon and having a 4 m 2 / g to 6 m 2 / g of carbonaceous particulate material composed of natural graphite particles having a BET SSA, and the particle size distribution D of the natural graphite particles coated with non-graphitic carbon 50 between 10 µm and 15 µm; wherein the content of natural graphite particles coated with non-graphite carbon is 10 wt% to 40 wt% of the total weight of the composition; When measured using a laser with an excitation wavelength of 632.8 nm, the I D / I G The ratio is 0.5 to 1.

2.

2. The composition of claim 1, wherein the synthetic graphite particles are further characterized by: i) D 50 has a particle size distribution of 10 µm to 30 µm; and / or ii) a c / 2 distance of 0.3354 nm to 0.3370 nm; and / or iii) 0.5 m 2 / g-4 m 2 / g of BET SSA; and / or iv) at least 2.22 g / cm 3 xylene density; and / or v) At least 0.8 g / cm after 400 taps 3 The tap density of vi) a crystal [004] to [110] reflection intensity ratio of less than 40; and / or vii) having a non-graphite carbon coating.

3. The composition of claim 1 or 2, wherein the natural graphite particles are further characterized by: i) D 90 Particle size distribution equal to or less than 40 µm; and / or ii) I of 0.7-1.1 when measured with a laser excitation wavelength of 632.8 nm D / I G ratio; and / or iii) a c / 2 distance of less than 0.3356 nm; and / or iv) a crystalline L of at least 90 nm as measured by XRD c value.

4. The composition of claim 1 or 2, wherein the natural graphite particles are further characterized by v) At least 0.8 g / cm after 400 taps 3 The tap density of vi) Crystal L of 100 nm-180 nm measured by XRD c value; and / or vii) a crystal [004] to [110] reflection intensity ratio greater than 45; and / or viii) Equal to or less than 30 wt% is represented as Q3 (S＝0.8) sphericity.

5. The composition according to claim 1 or 2, wherein the non-graphite carbon coating of the natural graphite particles coated with non-graphite carbon accounts for 0.5 wt% to 20 wt% of the total weight of the coated natural graphite particles.

6. The composition according to claim 1 or 2, wherein the non-graphite carbon coating of the natural graphite particles coated with non-graphite carbon is obtained by a method selected from chemical vapor deposition coating, physical vapor deposition coating, plasma coating, asphalt coating or amphiphilic surfactant coating.

7. The composition according to claim 6, wherein the non-graphite carbon coating is obtained by chemical vapor deposition.

8. The composition of claim 1 or 2, wherein the composition comprises one or more additives.

9. The composition according to claim 1 or 2, when used as a negative electrode active material, i) an electrode capacity of at least 350 mAh / g; and / or ii) a capacity retention at 2C of at least 20%; and / or iii) a relative increase in capacity retention at 2C of at least 20 wt% compared to an electrode made without the natural graphite particles coated with non-graphite carbon; and / or iv) at least 75% of the 3C constant current charge rate; and / or v) at least 60% of the 5C constant current charge rate; and / or vi) a constant current charge rate of at least 45% at 7C; and / or vi) a relative increase in constant current charge rate at 3C of at least 2% compared to an electrode made without the natural graphite particles coated with non-graphite carbon; and / or vii) a relative increase in constant current charge rate at 5C of at least 3% compared to an electrode made without the natural graphite particles coated with non-graphite carbon; and / or viii) a relative increase in constant current charge rate at 7C of at least 10% compared to an electrode made without the natural graphite particles coated with non-graphitic carbon.

10. The composition of claim 2, wherein the non-graphite carbon coating comprises less than 2 wt% of the total weight of the synthetic graphite particles.

11. The composition of claim 7, wherein the non-graphite carbon coating is obtained by chemical vapor deposition by treating a carbonaceous particulate starting material with a hydrocarbon gas at a temperature of 500-1200°C for a treatment time ranging from 3 to 120 minutes.

12. The composition according to claim 8, wherein the additive is selected from i) other carbonaceous particles, the weight range of the other carbonaceous particles being equal to or less than 10 wt%; and / or ii) Polymer binders.

13. The composition of claim 12, wherein the carbonaceous particulates are conductive carbon.

14. The composition according to claim 12, wherein the polymer binder is selected from styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxymethyl cellulose, polyacrylic acid or its derivatives, polyvinylidene fluoride or mixtures thereof.

15. A slurry in a liquid comprising the composition of any one of claims 1 to 14.

16. The slurry of claim 15, wherein the liquid is water or a water / alcohol mixture.

17. A method for preparing the composition according to any one of claims 1 to 14, comprising: The synthetic graphite as defined in claim 1, 2 or 10 is mixed with the natural graphite coated with non-graphitic carbon as defined in any one of claims 1, 3 to 7 or 11.

18. The method according to claim 17, which is carried out in the presence of a liquid.

19. The method according to claim 17, further comprising adding one or more additives as defined in claims 8 or 12-14.

20. Use of the composition defined in any one of claims 1 to 14 for preparing a negative electrode for a lithium ion battery.

21. The use according to claim 20, wherein the lithium-ion battery is used in electric vehicles, hybrid vehicles or energy storage batteries.

22. Use of natural graphite coated with non-graphite carbon as defined in any one of claims 1, 3 to 7 or 11 for the preparation of a composition suitable for use as an active material in a negative electrode.

23. Use of natural graphite coated with non-graphitic carbon as defined in any one of claims 1, 3 to 7 or 11 as a carbonaceous additive for improving the energy density and charge rate performance of a lithium ion battery while maintaining the power density of the battery compared to a battery using a negative electrode without the carbonaceous additive.

24. An electrode comprising the composition according to any one of claims 1 to 14 as an active material.

25. A lithium ion battery comprising the composition according to any one of claims 1 to 14 as an active material in a negative electrode of the battery.

26. An electric vehicle, hybrid vehicle or energy storage battery comprising the lithium ion battery according to claim 25.

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