Free particles and methods of preparation for use in electrochemical cells - Patent Application 20070122997

Abstract

Convenient methods for producing free particles (e.g., containing LiFePO4 or NMC) that may be particularly useful as electrode materials in lithium batteries and other applications are disclosed. Some methods involve dry mechanofusion of suitable feedstock particles and template particles, where the feedstock particles coat the template particles to form a coating; impact milling the coated template particles to detach particles of the coating from the template particles; and separating the detached free particles from the template particles. The novel free particles produced by these methods can be characterized by an intergranular layered structure that is distinguishable by its preferential orientation characteristics. Such free particles have uniquely low surface areas, and electrodes made with them have uniquely low porosity yet high loadings, and can exhibit excellent performance in electrochemical cells.

Description

[Technical Field]

[0001] [Citation by reference to any priority application] This application claims priority to U.S. Provisional Application No. 63 / 423,275, filed November 7, 2022, and U.S. Provisional Application No. 63 / 580,294, filed September 1, 2023, which are incorporated by reference herein in their entireties.

[0002] The present disclosure relates to convenient methods for making free particles that are particularly useful as electrode materials in lithium batteries and other applications. The present disclosure also relates to free particles and particulate materials that can be made by these methods, having uniquely low surface areas, and to electrodes made therewith that have uniquely low porosity but high loadings. [Background technology]

[0003] The development of rechargeable high-energy density batteries, such as Li-ion batteries, is of great technological importance. Typically, commercially available rechargeable Li-ion batteries use lithium transition metal oxide or lithium iron phosphate cathodes and graphite anodes. Although batteries based on such materials are approaching their theoretical energy density limits, significant research and development efforts continue to improve other important characteristics, such as cycle life, efficiency, and cost.

[0004] To manufacture a Li-ion battery cathode, a wet process can be used in which Li-ion battery cathode material is mixed with carbon black and a binder dissolved in a solvent to form a slurry. The slurry is then cast onto an electrode current collector. The cast cathode is heated to evaporate the solvent, resulting in the formation of a coating of Li-ion battery cathode material powder, carbon black, and binder (cathode coating) on ​​the surface of the electrode current collector. Typically, both sides of the current collector are coated. The cathode typically has a capacity of 2-4 mAh / cm per side, depending on the application. 2The cathode is coated with a coating amount (loading amount) per side corresponding to the practical capacity range of 1000 MPa. The dried cathode coating can have a porosity of approximately 50%. Li-ion battery cathodes can be calendered to increase energy density. Achieving a porosity of even 25-35% requires high calendering pressure (e.g., 200-300 MPa) that can crush the cathode particles, resulting in increased electrolyte reactivity, poor electrical contact, and reduced battery capacity.

[0005] LFP cathode materials have lower electronic conductivity and lower Li than oxide-based or spinel-based cathode materials with an intragranular layered crystal structure. + To overcome this drawback, LFP is made into small particles (e.g., 0.2-0.5 μm) and Li + The use of such LFP particles can reduce the diffusion length of the Li + Although it improves ionic conductivity, the large surface area of ​​small particles also increases electrolyte reactivity and reduces packing efficiency.

[0006] To increase the energy density of LFP electrodes, high calendering pressures have been employed. However, as explained by [Xin Ren, Zhenfei Li, Yi Zheng, Weichao Tian, ​​Kaicheng Zhang, Jingrui Cao, Shiyu Tian, ​​Jianling Guo, Lizhi Wen, Guangchuan Liang, “High Volumetric Energy Density of LiFePO4 Battery Based on Ultrasonic Vibration Combined with Thermal Drying Process”, Journal of the Electrochemical Society, 2020, 167, p.130523], “However, blindly increasing the pressure from the roller press or the number of rolls during the calendering process will reduce the porosity of the pole pieces and promote fragmentation of the active particles. Low porosity will cause insufficient wetting of the electrolyte, affecting the cycle performance of the LIB, and fragmentation of the active particles will also result in deterioration of the electrochemical performance of the LIB.” This can lead to particle fracture and a decrease in electrode porosity, which will result in poor electrolyte penetration and ultimately Li in the electrolyte. + The diffusion of

[0007] Various methods have been attempted to increase the energy density of Li-ion batteries. In Particuology, 2015, 22, p. 24, Lei Wen et al. reported that LFP-carbon composite spheres were used to achieve a 2.6 g / cm 3 reported a cathode coating density of 2.73 g / cm3, but to obtain acceptable performance, the LFP-GC spheres were highly porous. 3 reported achieving an LFP cathode coating density of 1 mg LFP / cm. 2 (or about 0.16mAh / cm 2 ) and is useful in practical cells (approximately 2–4 mAh / cm 2 ) is far below.

[0008] One method for producing particles is by ball milling. For example, U.S. Patent No. 8,999,054, by Keita Nagano et al. and Peter Wissling et al., "Metallic Effect Pigments: Fundamentals and Applications," Vincentz Network (April 1, 2006), describes the production of Al powder pigments by ball milling Al powder. In the ball milling process, the powder is reduced in size and flattened. A wet processing aid (e.g., stearic acid) is added to control the amount of cold welding that occurs so that large agglomerates do not form. In this process, the starting Al powder becomes larger than the final flake particles. Pee-Yew Lee et al., Journal of Materials Science, 1998, 33, p. 235, and Simeng Cao et al., Journal of the Electrochemical Society, 2022, 169, p. 060540 (hereinafter "Pee-Yew et al."), describe the synthesis of alloy flakes by ball milling. Ball milling powders that are ductile and can be bonded together by cold welding can produce flakes larger than the starting powder particles. Prolonging the ball milling process for an excessive period of time can embrittle the alloy used for milling, resulting in the fracture and breakage of the flakes. The ball milling process is also limited by the size of the balls that can be used practically. According to Pee-Yew Lee et al., "When the majority of grinding media have a diameter of more than 1.0 mm, fine aluminum powder is trapped between the grinding media, and this aluminum powder is difficult to grind and is not efficiently flaked. On the other hand, when the majority of grinding media have a diameter of less than 0.3 mm, the weight of the steel ball grinding media is too small, so the grinding force is reduced and the grinding time is too long, making it impossible to substantially grind the aluminum powder."Pee-Yew Lee et al. state that ball milling has limitations: "In other words, in the manufacturing method of the present invention, it is important to flake aluminum powder using a milling medium containing milling media having a diameter of 0.3 to 1.0 mm." Therefore, the ball milling method cannot impart a radius of curvature of less than 150 μm to the flakes. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 8,999,054 [Non-patent literature]

[0010] [Non-Patent Document 1] Xin Ren, Zhenfei Li, Yi Zheng, Weichao Tian, ​​Kaicheng Zhang, Jingrui Cao, Shiyu Tian, ​​Jianling Guo, Lizhi Wen, Guangchuan Liang, “High Volumetric Energy Density of LiFePO4 Battery Based on Ultrasonic Vibration Combined with Thermal Drying Process”, Journal of the Electrochemical Society,2020,167,p.130523 [Non-patent document 2] Lei Wen et al., “Particuology”, 2015, 22, p.24 [Non-patent document 3] Yong Wang et al., “Ionics”, 2021, 27, p.4687 [Non-patent document 4] Peter Wissling et al., "Metallic Effect Pigments: Fundamentals and Applications," Vincentz Network, April 1, 2006 [Non-patent document 5] Pee-Yew Lee et al., "Journal of Materials Science", 1998, 33, p.235 [Non-patent document 6] Simeng Cao et al., Journal of the Electrochemical Society, 2022, 169, p.060540 [Non-Patent Document 7] Robert Pfeffer, Rajesh N. Dave, Dongguang Wei, Michelle Ramlakhan, “Synthesis of engineered particulates with tailored properties using dry particle coating”, Powder Technology, 2001, 117, p. 40-67 [Non-patent document 8] WADollase, “J.Appl.Cryst.”, 1986, 19, p.267-272 [Non-Patent Document 9] ACLarson and RBVon Dreele, “General Structure Analysis System (GSAS)”, Los Alamos National Laboratory Report LAUR, 2004, p.86-748 [Non-Patent Document 10] Emil Zolotoyabko, “Basic Concepts of X-Ray Diffraction”, John Wiley & Sons, February 2014 Summary of the Invention [Problem to be solved by the invention]

[0011] In light of the above, there is a need for a method that can compact brittle powders into flakes with diameters between 5 and 25 μm. Additionally, if such curved flakes are desired, the ability to impart a radius of curvature of less than 150 μm is desirable.

[0012] There is a need to increase electrode coating density beyond current practice while maintaining or decreasing electrode surface area to reduce reactivity with electrolytes or electrolyte additives, while maintaining or exceeding electrode performance (i.e., high capacity retention and low polarization). The present disclosure addresses these needs and provides additional advantages as disclosed below. [Means for solving the problem]

[0013] In some aspects, the technology described herein relates to a method of making free particles, the method including the steps of obtaining a quantity of feedstock particles and a quantity of template particles; dry mechano-fusing the quantities of feedstock particles and template particles to form coated template particles comprising a feedstock particle coating on the template particles; impact milling the coated template particles to cause the feedstock particle coating to detach from the template particles and form free particles; and separating the free particles from the template particles.

[0014] In some embodiments, the technology described herein relates to methods in which the template particles are spherical and less than 200 μm in diameter.

[0015] In some embodiments, the technology described herein relates to methods in which the template particles are ZrO2.

[0016] In some aspects, the technology described herein relates to methods in which the feedstock particles comprise a transition metal oxide or a transition metal phosphate.

[0017] In some embodiments, the techniques described herein may be used to prepare raw material particles of A x T y M z O2 or A x T y M zPO4, where x≧0, y≧0.5, z≧0, A is one or more intercalable alkali metals, T is one or more first row transition metals, and M is selected from the group consisting of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, and Ta.

[0018] In some aspects, the technology described herein relates to methods where the raw particles comprise LiFePO4 and graphite, and the free particles comprise a blend of LiFePO4 and graphite.

[0019] In some aspects, the technology described herein relates to methods where the feed particles comprise NMC and the free particles comprise NMC.

[0020] In some embodiments, the techniques described herein relate to methods in which the amounts of the raw material particles and the template particles obtained are such that the ratio of the true volume of the raw material particles to the surface area of ​​the template particles corresponds to a coating thickness of 0.1 μm to 50 μm.

[0021] In some aspects, the technology described herein relates to methods where the impact milling is centrifugal impact milling.

[0022] In some embodiments, the technology described herein relates to methods in which the mechanofusion time ranges from 30 seconds to 5 hours.

[0023] In some embodiments, the technology described herein relates to methods in which the impact milling time ranges from 5 seconds to 1 minute.

[0024] In some embodiments, the technology described herein relates to methods further comprising heating the free particles separated from the template particles at a temperature greater than 200° C. to produce an electroactive positive electrode material.

[0025] In some aspects, the technology described herein relates to a free particulate material, including free particles made by a method including obtaining a quantity of feedstock particles and a quantity of template particles; dry mechano-fusing the quantities of feedstock particles and template particles to form coated template particles including a feedstock particle coating on the template particles; impact milling the coated template particles to cause the feedstock particle coating to detach from the template particles and form free particles; and separating the free particles from the template particles.

[0026] In some aspects, the technology described herein relates to an electrode for an electrochemical cell comprising a porous electroactive coating on a current collector, the electroactive coating comprising loose particulate matter made by a method comprising: obtaining a quantity of feedstock particles and a quantity of template particles; dry mechano-fusing the quantities of feedstock particles and template particles to form coated template particles comprising a feedstock particle coating on the template particles; impact milling the coated template particles to cause the feedstock particle coating to detach from the template particles and form loose particles; and separating the loose particles from the template particles.

[0027] In some aspects, the technology described herein provides a method for producing a free particulate material comprising free particles of an electroactive material comprising greater than 80 wt. % metal oxide or metal phosphate electroactive phase, having a density greater than 3 g / ml, and an average particle size in the range of 1 μm to 30 μm, wherein the metal oxide or metal phosphate electroactive phase consists essentially of crystalline grains with a size between 20 nm and 300 nm, the metal oxide and metal phosphate grains in the free particles have a preferential orientation with respect to a major plane of the particle having a preferential orientation parameter greater than 1.02 or less than 0.98, the free particles having an average internal porosity less than 20%, and a volumetric surface area of ​​the free particles of 30 m 2 / ml and the average aspect ratio of said free particles is greater than 1.5.

[0028] In some embodiments, the technology described herein relates to free particulate matter, wherein said free particles have an average aspect ratio of at least 5.

[0029] In some embodiments, the technology described herein relates to free particulate matter, wherein the free particles have an average aspect ratio of 1.5 or greater and less than 5.

[0030] In some aspects, the technology described herein relates to loose particulate matter that further comprises a conductive additive.

[0031] In some aspects, the technology described herein relates to a free particulate material in which the conductive additive comprises carbon.

[0032] In some aspects, the technology described herein relates to a loose particulate material wherein the carbon is graphite.

[0033] In some embodiments, the technology described herein relates to loose particulate material, wherein the grains have a crystallographic strain of less than 1%.

[0034] In some embodiments, the technology described herein relates to loose particulate matter, the grains of which are smaller than 200 nm.

[0035] In some embodiments, the technology described herein provides a method for producing flakes in which the free particles are greater than 80 wt. % LiFePO4, with an average flake diameter ranging from 5 μm to 50 μm, an average flake thickness ranging from 0.1 μm to 10 μm, an average aspect ratio of at least 5, and an average particle size of at least 8 μm. 2 / g.

[0036] In some embodiments, the technology described herein relates to free particulate matter wherein the average flake diameter is in the range of 5 μm to 25 μm and the average flake thickness is in the range of 0.1 μm to 5 μm.

[0037] In some embodiments, the technology described herein relates to a loose particulate matter in which the LiFePO4 consists of grains having an average size of less than 0.3 μm.

[0038] In some embodiments, the technology described herein relates to free particulate matter, wherein the free particles have curvature with a radius of curvature in the range of 10 μm to 100 μm.

[0039] In some embodiments, the technology described herein relates to a free particulate material, wherein the free particles are greater than 80 wt% LiFePO4, the LiFePO4 consisting essentially of crystalline grains, the LiFePO4 crystalline grains having a preferred orientation in the 0101 direction relative to a major plane of the free particles with a preferred orientation parameter of less than 0.98, and the free particles include carbon domains present between the LiFePO4 grains, the carbon domains ranging between 0.1 wt% and 10 wt%.

[0040] In some embodiments, the technology described herein relates to free particulate matter wherein the carbon domains have an average size of less than 100 nm.

[0041] In some embodiments, the technology described herein relates to a free particulate material, wherein the free particles are greater than 80 wt. % NMC, the NMC consisting essentially of crystalline grains, and the crystalline grains of the NMC have a preferential orientation in the

[0110] direction relative to the major planes of the free particles, the preferential orientation parameter being greater than 1.02.

[0042] In some embodiments, the technology described herein provides an electrode for an electrochemical cell comprising a porous electroactive coating on a current collector, the electroactive coating comprising greater than 80% by weight of free particulate matter and a binder, wherein the free particulate matter comprises free particles described herein, the electrode coating has an electrode porosity of less than 20%, and the loading of the electrode coating on the current collector is greater than 100 mAh / cm 2 In some aspects, the technology described herein relates to a lithium-ion rechargeable battery comprising the electrode.

[0043] In some aspects, the technology described herein relates to electrodes in which the free particulate matter comprises carbon.

[0044] In some aspects, the technology described herein relates to electrodes where the electrode coating has an electrode porosity of less than 15%.

[0045] In some embodiments, the technology described herein provides a current collector with a loading of 3 mAh / cm of the electrode coating on the current collector. 2 Regarding electrodes that are super.

[0046] In some aspects, the technology described herein relates to an electrode for a lithium-ion electrochemical cell comprising a porous electroactive coating on a current collector, the electroactive coating comprising greater than 10 wt. % free particles, the free particles being greater than 80 wt. % LiFePO4 grains, the free particles being flakes having an aspect ratio of at least 5, a flake diameter in the range of 5 μm to 50 μm, and a flake thickness in the range of 0.1 μm to 10 μm, the free particles comprising carbon domains between the LiFePO4 grains in the range of 0.1 wt. % to 10 wt. %, the free particles having an internal porosity of less than 20%, and the carbon domains having an average size of less than 100 nm.

[0047] In some embodiments, the technology described herein relates to an electrode in which the free particles are greater than 80 wt. % LiFePO4, and the LiFePO4 grains have a preferential orientation in the

[0101] direction with respect to the major planes of the free particles, with a preferential orientation parameter of less than 0.98. [Brief explanation of the drawings]

[0048] [Figure 1a] 1 shows a schematic diagram of method steps according to some embodiments. [Figure 1b] 1 illustrates a schematic representation of a Mechanofusion system suitable for use in improved microgranulation methods according to some embodiments. [Figure 2] 1 shows an SEM image of ZrO2 template particles used in the examples. [Figure 3] 1 shows an SEM image of a comparative particulate material in an example. [Figure 4] FIG. 3 shows the X-ray diffraction pattern of the comparative particulate matter. [Figure 5] Figure 3 shows an SEM image of a cross section of an electrode coating made using a comparative particulate material. [Figure 6] FIG. 3 shows the voltage curves for the first two cycles of a lithium cell fabricated using an electrode containing comparative particulate matter. [Figure 7] 19 shows the polarization of the lithium cell of FIG. 6 plotted as a function of cycle number. For comparison, the polarization of the lithium cell of FIG. 19 containing particulate matter of some embodiments is also shown. [Figure 8] 8 shows the capacity and coulombic efficiency of the cell of FIG. 7 plotted as a function of cycle number. [Figure 9] 1 shows an SEM image of ZrO2 template particles with a uniform coating of unheated LFP / carbon composite after 20 minutes of mechanofusion processing, according to some embodiments. [Figure 10] 9 shows an SEM image of the coated ZrO2 template particles from FIG. 9 after impact milling. [Figure 11]1 shows an SEM image of unheated LFP / carbon composite flake free particulate matter. [Figure 12] FIG. 11 shows the X-ray diffraction pattern of unheated LFP / carbon composite flake free particulate matter. [Figure 13] 13 shows the SEM image of the LFP / carbon composite flake free particulate matter after heating from FIG. [Figure 14] 1 shows an X-ray diffraction pattern of particulate matter IE1 produced in an example. [Figure 15] 1 shows an SEM image of a single IE1 particle whose surface was etched using a focused gallium ion beam. [Figure 16] 1 shows an SEM image of a single IE1 particle cross-sectioned with a broad argon ion beam, the cross-section being perpendicular to the basal plane of the flake. [Figure 17] The same image as in Figure 16 is shown, except that the void lines are highlighted with black lines. [Figure 18] 1 shows an SEM image of a cross section of an electrode coating made with IE1 particulate matter. [Figure 19] 1 shows the voltage curves for the first two cycles of a lithium cell made with an electrode containing IE1 particulate matter. [Figure 20] The capacities of lithium half-cells made with electrodes containing particulate material IE1 and comparative particulate material CE1 are compared at various charge and discharge rates. [Figure 21] An SEM image of particulate matter IE2 is shown. [Figure 22] 1 shows an XRD pattern of the particulate material of Example IE2. [Figure 23] 1 shows a cross-sectional image of an electrode fabricated using particulate matter IE2 as the active material. [Figure 24] 1 shows the discharge capacity versus cycle number of cells with particulate material IE2 and comparative particulate material CE1 cycled at different discharge rates as indicated. [Figure 25] 1 shows an SEM image of NMC622 particulate matter. [Figure 26]1 shows an SEM image of NMC622 particulate matter coated onto a ZrO2 sphere. [Figure 27] 1 shows an SEM image of liberated NMC622 flake particulate matter. [Figure 28] 28 shows the XRD pattern of the liberated NMC622 flake particulate material of FIG. 27. [Figure 29] 1 shows an SEM image of liberated NMC622 flake particulate material of Example IE3. [Figure 30] 1 shows the XRD pattern of the liberated NMC622 flake particulate material of Example IE3. [Figure 31] 1 shows an SEM image of the BIB cross section of the electrode coating of IE3. [Figure 32] 1 shows the voltage curves of coin cells made with loose NMC622 flake particulate matter of Example IE3 as the active material of the working electrode. [Figure 33] 3 shows the capacity of the same cell shown in FIG. 31 plotted as a function of cycle number. DETAILED DESCRIPTION OF THE INVENTION

[0049] A desirable free particulate material consisting essentially of free particles (e.g., a compound of the general formula A for use in lithium batteries and other applications) is x T y M z O2 or A x T y It has been discovered that electroactive materials having the general formula A (including those having PO4) can be easily and quickly prepared by a method involving mechanofusion followed by impact milling. x T y M z O2 or A x T yIn the formula (I), x≧0, y≧0.5, and 0.2≧z≧0, A comprises one or more intercalable alkali metals (such as lithium in the case of lithium-ion batteries), T comprises one or more first-row transition metal elements, and M comprises one or more metal elements other than alkali metals or first-row transition metal elements. In the mechanofusion process, suitable feedstock particles and template particles are dry-mechanofused, with the feedstock particles coating the template particles to form a coating. For example, mechanofusion can involve coating the template particles with the feedstock particles using mechanical forces such as high shear and / or high pressure, and can be a dry process that does not use solvents. The latter impact milling process is then used to detach the coating from the template particles, forming a free-particulate material comprising free particles, or free particles (i.e., particles "liberated" from the template particles). Surprisingly, the free particles produced by these methods can be structurally distinct from prior art particles in that they may have an intergranular layered structure. Such structures are evidenced by the atypical preferential orientation of the grains that the free particles comprise. Such free particles can have significantly lower surface areas than those produced by conventional techniques. Furthermore, electrodes can be fabricated using such free particles with significantly lower porosity but higher loadings, further providing surprisingly improved performance in electrochemical cells.

[0050] Also described are unique free particles made by the methods and embodiments herein that are useful in electrochemical cells, such as lithium-ion batteries. In some embodiments, the free particles include LFP, NMC, and / or graphite. Such materials enable extremely high electrode densities to be achieved with conventional calendering pressures. At the same time, and unexpectedly, they can reduce reactivity with the electrolyte, improving cycle life and rate capability. The free particles may have an average particle size ranging from 1 to 30 μm. In some embodiments, the free particles are flakes and may have an average particle thickness ranging from 0.1 to 10 μm and an average aspect ratio of at least 5 (e.g., ranging from 5 to 100). In some applications, the free particles may have an average particle width ranging from 5 μm to 25 μm, an average particle thickness ranging from 0.1 to 5 μm, and an average aspect ratio ranging from 10 to 100. Additionally, unique electrodes for electrochemical cells, such as Li-ion (also referred to herein as "lithium-ion" or "lithium ion") batteries, are described that incorporate the free particles and methods described above. Such electrodes may have very high densities while maintaining very high gravimetric capacity and low polarization.

[0051] [Method of producing free particles] Some embodiments include methods for producing high density free particles from smaller feedstock particles. In some embodiments, the methods utilize a combination of mechanofusion with template particles, impact milling, and particle separation (classification) processes.

[0052] One aspect of the present disclosure involves a method for producing loose particles, referred to herein as improved microgranulation or "MM." The MM method is shown in Figure 1a and includes combining appropriate feedstock particles and template particles into a mixture, mechano-fusion-processing the mixture until the feedstock powders form a coating on the template particles, recovering the coated template particles and subjecting them to impact milling to detach some or all of the coating layer from the template particles in the form of loose particles (e.g., flakes) to form a mixture of loose particles and template particles, and then subjecting the mixture of loose particles and template particles to a separation process to collect the loose particles separated from the template particles.

[0053] In some embodiments, the loose particles or loose particulate matter can be produced by a method including the following steps: providing feedstock particles and template particles; dry mechanofusion of the feedstock particles and the template particles to coat the template particles with the feedstock particles and form coated template particles; and impact milling of the coated template particles to cause the feedstock coating on the template particles to detach from the template particles and form detached loose particles (e.g., flakes). In some embodiments, the feedstock coating can detach from the template particles to form a detached loose particulate matter comprising the loose particles. Optionally, the method can further include separating the detached loose particles from the template particles, thereby obtaining the loose particles. The loose particulate matter can comprise two or more loose particles and is free or substantially free of template particles.

[0054] Preferred template particles include those that are spherical, monodisperse, composed of a hard material, and chemically inert to the raw material particles, the mechanofusion vessel, and the processing atmosphere. Preferred template particles are those less than 200 μm in size. For example, the template particles may be less than 200 μm, less than 150 μm, less than 100 μm, less than 75 μm, less than 60 μm, less than 50 μm, or any range consisting of any of the foregoing values. Generally, template particles should be greater than 5 μm in size, more preferably greater than 10 μm in size. In some embodiments, the template particles used can be spherical and less than 200 μm in diameter, i.e., significantly smaller than the balls used in ball milling. Exemplary template particles include those composed of ZrO. In some embodiments, the template particles may have an average particle size of 50 μm.

[0055] Preferred feedstock particles are smaller than the average template particle size. Preferred feedstock particles have an average particle size less than 1 / 10 of the average template particle size, less than 1 / 50 of the average template particle size, less than 1 / 100 of the average template particle size, or even smaller. In some embodiments, exemplary feedstock particles have an average particle size of 1 μm and are used with template particles having an average particle size of 50 μm. In some embodiments, exemplary feedstock particles have an average particle size of 0.5 μm and are used with template particles having an average particle size of 50 μm. In some embodiments, the feedstock particles may be more than 1 / 10 of the average template particle size, but are reduced to less than 1 / 10 of the average template particle size early in the MM process.

[0056] The feedstock particles can include electroactive materials for rechargeable batteries, such as Li-ion batteries. The electroactive material feedstock composition for use in rechargeable batteries can be represented by the general formula A x T y M z O2 or A x T y Mz PO4, where x, y, and z are numbers with x≧0, y≧0.5, z≧0, and y+z=1; A is one or more intercalable alkali metals; T is one or more first row transition metals; and M is a dopant consisting of one or more metallic elements that are not alkali metals or first row transition metals. In some embodiments, x, y, and z are numbers with 1.2≧x≧0.9, 1≧y≧0.9, and 0.1≧z≧0. For Li-ion batteries, A is lithium. In some embodiments, the formula A x T y M z The O2-containing electroactive material has an α-NaFeO2-type structure. In some embodiments, the O2-containing electroactive material has a structure of formula A x T y M z The electroactive material having PO4 has an olivine structure. In some embodiments, the raw material particles can further include graphite. In some embodiments, the raw material is compositionally similar to the electroactive positive electrode material produced by the processes herein.

[0057] The above-mentioned general formula A x T y M z In the electroactive material represented by O2, T can be comprised of one or more first-row transition metals, and M is a dopant comprised of one or more metallic elements that are not alkali metals or first-row transition metals. In some embodiments, air-stable versions of transition metal oxides can be employed for ease of fabrication. In these embodiments, x is typically equal to about 1, y + z is about 1, and z is 0 or greater. In some embodiments, x is equal to 1, y + z is 1, and z is 0 or greater. In some embodiments, x is about 1, y + z is about 1, and z is less than about 0.1. In some embodiments, x is 1, y + z is 1, and z is less than 0.1. Optionally, z can be 0 when no dopant is present.

[0058] The above-mentioned general formula A xT y M z In some embodiments using an electroactive material represented by O2, T consists of one or more first row transition metals including cobalt (Co), nickel (Ni), or manganese (Mn). In some embodiments, T is selected from the group consisting of Co, Ni, and Mn. In some embodiments, T is selected from the group consisting of Ni and Mn. In other embodiments, T consists solely of Co. In some embodiments, when z is greater than 0, M is selected from the group consisting of one or more of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, and Ta.

[0059] The above-mentioned general formula A x T y M z In some embodiments using an electroactive material represented by O, T can include Ni, Mn, and Co (such as the material known as "NMC"). NMC is a LiFePO4 alloy with an α-NaFeO structure. x Ni f Mn g Co h O2, where x is about 1, f, g, and h are all greater than 0, and f+g+h=about 1. Examples include LiNi 0.6 Mn 0.2 Co 0.2 In some embodiments, the NMC may further include a small amount of a dopant element M, such as Li. x Ni f Mn g Co h M z In O2, M is selected from the group consisting of one or more of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, and Ta, and z is greater than 0 but less than 0.1.

[0060] The above-mentioned general formula A x T y M z In some embodiments using an electroactive material represented by α-NaFeO, the raw material particles may be LiFeO having an α-NaFeO structure. xNi j Mn k M z The raw material particles may include so-called "Co-free NMC" materials having a composition of LiMnO, where x is about 1, j+k+z=about 1, z<0.1, and M includes one or more dopant elements (e.g., Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, or Ta). In some embodiments, x is 1, j+k+z=1, and z<0.1. In some embodiments, the raw material particles may have a composition of LiMnO.

[0061] The above-mentioned general formula A x T y M z In some embodiments using an electroactive material represented by O2, T includes Ni and Co and M is one or more of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, or Ta. In some embodiments, M is aluminum (e.g., the material known as "NCA"). In some embodiments, T can include only Co, such as LiCoO2 (LCO). In some embodiments, LCO can further include one or more dopants M.

[0062] The above-mentioned general formula A x T y M zIn the electroactive material feedstock composition represented by PO4, A may be Li, T comprises one or more first row transition metals, x is equal to about 1, y is about 1, and z is less than 0.1. In some embodiments, T is Fe. In some embodiments, T is Mn. In some embodiments, T comprises Mn and Fe. In some embodiments, when z is greater than 0, M can comprise one or more of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, and Ta. In some embodiments, the feedstock particles can comprise LiFePO4 ("LFP"). In some embodiments, the feedstock particles can comprise LiFePO4 and graphite, where the free particles produced comprise a blend of LiFePO4 and graphite. In some embodiments, the feedstock particles can comprise lithium manganese phosphate (LMP) or lithium iron manganese phosphate (LMFP).

[0063] The amounts of feedstock particles and template particles employed in the present method may be selected to achieve an approximate desired feedstock coating thickness on the template particles. For example, these amounts may be selected so that the ratio of the true volume of the feedstock particles to the surface area of ​​the template particles corresponds to a feedstock coating thickness of 0.1 μm to 50 μm, 0.1 μm to 40 μm, 0.1 μm to 20 μm, or 0.1 μm to 10 μm. For example, the feedstock coating thickness may be 0.1 μm, 1 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or a range consisting of any of the foregoing values. The true volume of the feedstock particles may be determined from their true density, which can be obtained from X-ray diffraction or pycnometry measurements.

[0064] When the free particles produced are flakes, the flakes may be non-planar and curvature-imparted. This curvature may be imparted to the flake particles by the surface curvature of the template particles. Therefore, if it is desired to reduce the curvature of the flakes, it may be desirable to use larger template particles. However, using template particles that are too large may impede the flow of particles through the press head gap during the mechanofusion process. Template particle radii that are less than 200 μm in size are generally preferred.

[0065] In some embodiments, mechanofusion (also referred to as "MF") is a dry process that generates a high shear and / or high pressure field. Mechanofusion can have the advantage of being relatively simple and inexpensive. For example, in embodiments involving dry processes, no solvents are required, making it potentially attractive for environmentally friendly commercial manufacturing. Figure 1b schematically illustrates an MF system 1 suitable for use in some embodiment methods. It includes a rotating cylindrical chamber 2 in which a fixed circular press head 3 and a fixed scraper 4 are disposed. The radius of the press head 3 is smaller than that of the chamber 2, and the clearance space between the press head 3 and the chamber wall 5 typically ranges from 1 to 5 mm. The clearance between the scraper 4 and the chamber wall 5 is smaller, typically about 0.5 mm. Preferably, these clearances are adjustable to optimize the process depending on factors such as chamber size, particle size, and powder hardness.

[0066] The operation of the MF system 1 is simple. During use, a particle mixture 6 is loaded into the chamber 2, which is then sealed. As the chamber rotates, the particle mixture 6 is forced against the chamber wall 5 by centrifugal force. This forces the particle mixture through the converging space between the fixed press head 3 and the rotating chamber wall 5, creating a high-shear, high-pressure field. As the particles emerge from the diverging space in the press head region, they adhere to each other and the chamber wall. A scraper 4 scrapes off the particle mixture 6 adhering to the chamber wall 5. The sheared particle mixture is then redispersed within the chamber and moves again toward the press head region. Appropriate operating parameters for the MF system can be expected to vary depending on the type and amount of particles employed and the final desired properties of the loose particulate material produced. Those skilled in the art will be able to readily determine appropriate operating parameters for their particular situation based on guidance from this disclosure. Therefore, typical mechanofusion times can range from 30 seconds to 5 hours. For example, the mechanofusion time may be 10 seconds, 30 seconds, 1 minute, 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or a range consisting of any of the foregoing values.

[0067] In other embodiments, mechanofusion can include other processes known to fuse small particles onto larger particles. For example, in some embodiments, the mechanofusion process can be achieved using a hybridizer (e.g., manufactured by Nara Machinery Manufacturing Co., Ltd., Japan), magnetically assisted impaction coating, or a Theta Composer. In some embodiments, the mechanofusion process can be achieved using the method described in [Robert Pfeffer, Rajesh N. Dave, Dongguang Wei, Michelle Ramlakhan, "Synthesis of engineered particulates with tailored properties using dry particle coating," Powder Technology, vol. 117, 2001, pp. 40-67].

[0068] In some instances, feedstock particles may have poor adhesion to each other and to the template particles, making the MM process difficult to achieve. To improve adhesion between the feedstock particles and the template particles, an adhesion promoter in the form of a solvent and / or binder can be included in the mixture of feedstock powder and template particles prior to the mechanofusion process. Suitable solvents include mineral oil, poly(vinyl alcohol) (PVA), n-methyl-2-pyrrolidone (NMP), propylene glycol, and water. Suitable binders include polymers such as polyvinylidene difluoride (PVDF), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polytetrafluoroethylene (PTFE), polyethylene (PE), and polypropylene (PP). Other suitable binders include pitch, phenolic resin, and polyacrylonitrile.

[0069] In some instances, only a solvent can be used as the adhesion promoter. In some instances, only a binder can be used as the adhesion promoter. For example, a powdered binder can be used as the adhesion promoter. In some instances, a binder dissolved in a solvent, such as a solution of PVDF in NMP, CMC in water, or PAA in water, can be used as the adhesion promoter. In some embodiments, a method can be employed to combine the adhesion promoter with the raw material particles prior to the MM mechanofusion step. Such a method can include subjecting a mixture of the adhesion promoter and the raw material particles to ball milling, vibratory milling, planetary milling, or other communication or blending methods. In some embodiments, the use of an adhesion promoter is effective in enabling the raw material particles to adhere to each other and to the template particles, thereby enabling the production of free particles by the MM process. In some embodiments, the free particles produced can include only the raw material particles (e.g., if the adhesion promoter evaporates during the MM process), and the MM process can be a substantially dry process. However, more commonly, the free particles produced include the raw material particles and the adhesion promoter, which may be desirable in the final product. In some instances, the adhesion promoter can be removed from the product loose particles by additional processing (e.g., heating). In some embodiments, using an excessive amount of adhesion promoter can cause the raw material particles to form a paste or cause undesirable agglomeration. Therefore, it is often desirable to use the minimum amount of adhesion promoter that allows for the production of loose particles by the MM process. In some embodiments, the use of an amount of adhesion promoter that is no greater than 20 wt. %, 10 wt. %, 5 wt. %, or 2 wt. % (or a range consisting of any of the foregoing values) of the amount of raw material particulate material can be effective to allow for the production of loose particles by the MM process.

[0070] Impact milling involves subjecting coated template particles to impacts or collisions to affect the detachment of the template particle coating in the form of loose particles (e.g., flakes) without excessively damaging the resulting loose particles (or template particles). Damage to the loose particles in this process can cause them to break down into fine particles, resulting in loose particulate matter with high surface area or low packing efficiency, which is undesirable in some embodiments. Some preferred impact milling methods include jet milling, pin milling, and centrifugal impact milling, as well as variations thereof. Impact milling processes that include a classification (separation) step to remove and collect the loose particles produced are particularly advantageous. On a small laboratory scale, impact milling can be performed using a kitchen blender or coffee grinder. Typical impact milling times can range from 5 seconds to 1 minute. For example, impact milling times can be 2 seconds, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 1 minute, 1 minute 30 seconds, 2 minutes, or a range consisting of any of the foregoing values. Some of the embodiments disclosed herein may employ various impact milling techniques known to those skilled in the art, such as centrifugal impact milling.

[0071] It is desirable that the product free particulate matter be free of template particles. Therefore, a separation process can be used to recover the free particles that have detached from the template particles. Separation processes include particle classification processes. Particularly useful methods for separation processes are cyclone air classification and sieving.

[0072] In some embodiments, it may be useful to perform additional processing steps on the free particles of the product of the MM process. For example, in some instances, the MM process may introduce crystalline defects. In some instances, it may be desirable to perform a final heating step under a controlled atmosphere to improve the crystallinity of the free particles of the product. In other instances, it may be desirable to chemically react the free particles of the product with other reagents. For example, in the synthesis of free-particle NMC by the MM method, it is expected that the MM treatment of mixed transition metal hydroxides will produce mixed metal hydroxide free particles, which can then be milled with an appropriate amount of a lithium source (e.g., Li2CO3) and heated in an oxygen-containing atmosphere (e.g., air or pure oxygen) to produce free NMC particles. In some embodiments, a final heating step may also be used to react the free particles and free particulate material with a lithium source (e.g., Li2CO3 or LiOH).

[0073] In some embodiments, the free particulate matter is subjected to a final heating step to produce an electroactive material. In some embodiments, the final heating step may involve heating the free particulate matter under an inert gas atmosphere, such as N or Ar. In some embodiments, the final heating step may involve heating the free particulate matter under an oxygen-containing atmosphere, such as O or air. In some embodiments, the final heating step may involve heating the free particulate matter under a reducing atmosphere, such as H or a H / N mixture. In some embodiments, the final heating step may involve heating the free particulate matter under a vacuum. Typically, the temperature used in the final heating step is greater than 200°C. In some embodiments, particularly for cathode materials, the temperature used in the final heating step can range from 500°C to 1200°C. The duration of the final heating step typically ranges from 30 minutes to one week, more typically from one hour to 24 hours. In some embodiments, the final heating step may include multiple individual heating steps in which the free particulate matter is heated under different atmospheres, at different temperatures, and for different lengths of time. Final heating of the free particles for the cathode material can convert the free particles into electroactive cathode material.

[0074] In some embodiments, the feedstock particles comprise compounds capable of forming electroactive materials for rechargeable batteries, such as Li-ion batteries, upon heating. The free particulate matter (free or substantially free of template particles) formed after MF, impact milling, and separation can then be heated in a final heating step to form electroactive material free particulate matter. As an example, the feedstock particles can comprise Ni-Mn-Co hydroxide, resulting in the formation of free particulate matter comprising Ni-Mn-Co hydroxide. The free particulate matter comprising Ni-Mn-Co hydroxide can be heated with a lithium source (e.g., Li2CO3 or Li(OH)) in a final heating step (e.g., in air or oxygen at 700°C to 900°C for 1 hour to 24 hours) to form free NMC particulate matter. In other embodiments, the feedstock particles can comprise a mixture of Ni, Mn, or Co oxides, producing free particulate matter comprising Ni-Mn-Co oxide, which can be combined with a lithium source and heated in a final heating step to form free NMC particulate matter in a similar manner. In other embodiments, the raw particles can include metal phosphates, and free particulate matter comprising metal phosphates can be produced. In some embodiments, the free particulate matter comprising metal phosphates can be heated in a final heating step to produce free LFP or free LMFP particulate matter.

[0075] Using the methods disclosed herein, loose particulate or loose particulate materials can be rapidly prepared. In the following examples, a batch process can be employed, and successful mechanofusion and impact milling times can be on the order of minutes. However, continuous processes may be considered for either or both steps, and these times may vary accordingly.

[0076] The methods disclosed herein can be used to produce novel free particles / free particulate materials and resulting electrodes that may have unexpectedly advantageous properties. Furthermore, the methods disclosed herein are environmentally friendly and advantageous for industrial applications because they do not require the use of solvents and for many other reasons.

[0077] Those skilled in the art will be able to easily prepare, for example, LiNi using the methods disclosed herein. f Mn g Co h It will be further understood that it is anticipated that many other related free particulate materials can be produced, such as O2 (where f, g, and h are all greater than 0 and f+g+h=1) (or NMC) free particulate material, flake NMC free particulate material, LCO free particulate material, NCA free particulate material, NMC / carbon free particulate material, and similar such materials.

[0078] In further embodiments, the methods disclosed herein can be utilized to make free particulate electroactive materials for battery chemistries such as Na-ion, K-ion, Mg, and rechargeable battery chemistries. By way of example, in the synthesis of electroactive materials for rechargeable Na-ion and K-ion batteries, the free particulate material can be represented by the general formula A x T y M z O2 or A x T y M z PO4, where x, y, and z are numbers with x≧0, y≧0.5, and z≧0; x, y, and z are numbers with 0≦x≦1.2, 0.5≦y≦1, and 0≦z≦0.2, and y+z=1; A is one or more intercalable alkali metals; T is one or more first-row transition metals; and M is a dopant consisting of one or more metallic elements that are not alkali metals or first-row transition metals. For Na-ion batteries, A is sodium. For K-ion batteries, A is potassium. In some embodiments, the formula A x T y M zThe O2-containing electroactive material has an α-NaFeO2-type structure. In some embodiments, the O2-containing electroactive material has a structure of formula A x T y M z The PO4-containing electroactive material has an olivine structure. In some embodiments, the raw material particles can further include amorphous graphite.

[0079] [Free particulate matter] Another aspect of the present disclosure is a unique free particulate material for use in the positive or negative electrodes of electrochemical cells, such as Li-ion batteries. Such free particulate material and electrodes made therefrom can have unexpectedly advantageous properties. For example, the free particulate material has a surprisingly low surface area (e.g., less than 8 m 2 / g or even less than 6m 2 The LFP graphite composite flake particulate material can include flake free particles having a densitometric value of less than 1 / g. As demonstrated in the examples below, it has been found that positive electrodes incorporating the LFP graphite composite flake particulate material can be fabricated at desirable loadings and exhibit excellent electrochemical performance while achieving excellent coating density at low calendaring pressures. It has been found that the microstructure of such novel free particles is unique, and that the free particulate material may be particularly useful as an active material in Li-ion batteries.

[0080] In some embodiments, the free particulate material comprises free particles comprising greater than 80% by weight of a metal oxide or metal phosphate electroactive phase. For example, in some embodiments, the free particles are greater than 80% by weight of LiFePO4. For example, in other embodiments, the free particles in the free particulate material may be greater than 80% by weight of NMC. In some embodiments, the free particles comprise greater than 80%, 85%, 90%, or 95% by weight of a metal oxide or metal phosphate electroactive phase (e.g., comprising grains of the metal oxide or metal phosphate electroactive phase). In some embodiments, the free particles consist of 100% by weight of a metal oxide or metal phosphate electroactive phase. In some embodiments, the electroactive phase is for use in a rechargeable battery, such as a Li-ion battery. In some embodiments, the electroactive layer comprises a compound represented by the general formula A x T y M z O2 or A x T y M z PO4, where x, y, and z are numbers with x≧0, y≧0.5, and z≧0, and x, y, and z are numbers with 0≦x≦1.2, 0.5≦y≦1, and 0≦z≦0.2, and y+z=1, A is one or more intercalable alkali metals, T is one or more first row transition metals, and M is a dopant consisting of one or more metallic elements that are not alkali metals or first row transition metals. In the case of a Li-ion battery, A is lithium. In some embodiments, the formula A x T y M z The O2-containing electroactive phase has an α-NaFeO2-type structure. In some embodiments, the O2-containing electroactive phase has a structure of formula A x T y M z The electroactive phase with PO4 has an olivine structure.

[0081] In some embodiments, the free particulate matter comprises free particles having a density greater than 3 g / ml, hi some embodiments, the free particles have a density greater than 3 g / ml, greater than 4 g / ml, greater than 5 g / ml, greater than 6 g / ml, or even greater.

[0082] In some embodiments, the free particulate matter comprises free particles having an average particle size in the range of 1 to 30 μm. In some embodiments, the free particulate matter comprises free particles having an average size in the range of 5 μm to 30 μm. In embodiments, the free particles may have an average size ranging from 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, or a range consisting of any of the foregoing values.

[0083] In some embodiments, the free particles have an average internal porosity of less than 20%. In some embodiments, the free particles have an internal porosity of less than 10%, less than 5%, or even less than 2%. For example, the free particulate matter can include constituent free particles having an average internal porosity of less than 20%, e.g., 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, substantially 0%, or a range consisting of any of the foregoing values.

[0084] In some embodiments, the volumetric surface area of ​​the free particles is greater than 30 m 2 In some embodiments, the volumetric surface area is less than 30 m / ml. 2 / ml or less, 29m 2 / ml, less than 28m 2 / ml, less than 27m 2 / ml or less, 26m 2 / ml or less, 25m 2 / ml or less, 24m 2 / ml or less, 23m 2 / ml or less, 22m 2 / ml or less, 21m 2 / ml, less than 20m 2 / ml or less, 19m 2 / ml or less, 18m 2 / ml or less, 17m 2 / ml or less, 16m 2 / ml or less, 15m 2 / ml or less, 14m 2 / ml or less, 13m 2 / ml or less, 12m 2 / ml or less, 11m 2 / ml, less than 10m 2 / ml or less, 9m 2 / ml or less, 8m 2 / ml, less than 7m 2 / ml or less, 6m 2 / ml, less than 5m 2 / ml, less than 4m 2 / ml or less, 3m 2 / ml or less than 2m 2 In some embodiments, the free particles are less than 8 m / ml, or a range consisting of any of the preceding values. 2 In some embodiments, the free particles preferably have a surface area of ​​less than 6 m 2 In some embodiments, the free particles have a low specific surface area, i.e., less than 20 m / g. 2 / g, less than 10m 2 / g or less, 8m 2 / g, or even less. In some embodiments, such free particles have a lower volumetric surface area, i.e., less than 20 m 2 / ml or less, 15m 2 / ml or less, 8m 2 / ml or even smaller volumetric surface area.

[0085] In some embodiments, the free particles have a flake morphology. In some embodiments, the free particulate material has an average flake diameter in the range of 5 to 50 μm. In some embodiments, the average flake diameter is in the range of 5 to 25 μm. In some embodiments, the average flake diameter is 5 to 50 μm, e.g., 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or a range consisting of any of the foregoing values. In some embodiments, the free particles have an average flake thickness in the range of 0.1 to 10 μm. In some embodiments, the average flake thickness is in the range of 0.1 to 5 μm. In some embodiments, the average flake thickness is 0.1 to 10 μm, e.g., 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range consisting of any of the foregoing values.

[0086] In some embodiments, the average aspect ratio of the free particles is greater than 1.5. In some embodiments, the free particles may have an average aspect ratio of at least 5. In some alternative embodiments, the average aspect ratio is in the range of 1.5 or more and less than 5. In some embodiments, the average aspect ratio of the free particles is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or more, or a range consisting of any of the foregoing values. In some embodiments, the free particulate material comprises free particles having a flake morphology with an aspect ratio of at least 5. In some embodiments, the free particulate material comprises free particles having a substantially oblong or potato-like morphology with an aspect ratio of 1.5 or more and less than 5.

[0087] In some embodiments, the free particles have a curvature. In some embodiments, the radius of curvature is in the range of 10 to 100 μm. In some embodiments, the radius of curvature is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm, or a range consisting of any of the foregoing values.

[0088] In some embodiments, the free particulate matter comprises free particles having a size of 20 nm to 300 nm and comprising greater than 80% by weight of grains. In some embodiments, the free particles of the free particulate matter comprise metal oxide grains or metal phosphate grains. In some embodiments, the grains in the free particles have a crystallographic strain of less than 1%, e.g., less than 0.8%, less than 0.5%, less than 0.3%, less than 0.1%, less than 0.01%, or even lower, or a range consisting of any of the foregoing values.

[0089] In some embodiments, the grains are less than 200 nm in size. In some embodiments, the free particles have an internal microstructure comprising more than 80 wt. % grains that are sized 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, about 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, or a range consisting of any of the foregoing values. In some embodiments, the grains have an average size of less than 0.3 μm. In some embodiments, the grains are comprised of LiFePO4.

[0090] In some embodiments, the free particles include intergranular layers, and the electroactive phase therein has a preferred crystalline orientation relative to these intergranular layers. In some embodiments, the crystalline grains are further arranged in intergranular layers that are generally parallel to one another. In some embodiments, layered arrangements of grains, voids, or cracks in the free particles may also be observed, for example, in SEM images of the free particle cross-sections (e.g., repeat distances of less than 600 nm). The average distance between these layered arrangements in the free particles may also be referred to as the intergranular layer thickness. The presence of such intergranular layers can be detected and confirmed by the presence of preferred orientation in a sample of the free particulate material as measured by X-ray diffraction. In some embodiments, a preferred orientation parameter greater than 1.02 or less than 0.98 can indicate that the grains comprising the free particles are preferentially aligned with the plane of the particle's largest dimension, indicating that the grains are arranged in intergranular layers.

[0091] In some embodiments, the metal oxide and / or metal phosphate grains in the free particles have a preferred orientation relative to the major planes of the particles, with a preferred orientation parameter greater than 1.02 or less than 0.98. For example, in some embodiments, crystalline grains (e.g., of LiFePO4) have a preferred orientation relative to the major planes of the free particles in the

[0101] direction with a preferred orientation parameter less than 0.98, less than 0.97, less than 0.96, less than 0.95, less than 0.94, less than 0.93, or even less (or a range consisting of any of the foregoing values). For another example, in other embodiments, crystalline grains (e.g., of NMC) have a preferred orientation relative to the major planes of the free particles in the

[0110] direction with a preferred orientation parameter greater than 1.02, greater than 1.03, greater than 1.04, or greater (or a range consisting of any of the foregoing values).

[0092] In some embodiments, the free particles can further include a conductive additive such as carbon (e.g., graphite). The conductive additive can be amorphous or non-crystalline, such as graphite. For example, in some embodiments, the conductive additive is located between intergranular layers. In some embodiments, the conductive additive is an inert phase. For example, in some embodiments, the free particles include carbon domains in the range of 0.1 to 10 wt.% present between crystalline grains (e.g., LiFePO4 grains). For example, the conductive additive (e.g., carbon domains) can include 0.1 wt.%, 0.2 wt.%, 0.5 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, or a range consisting of any of the foregoing values. In some embodiments, these carbon domains have an average size of less than 100 nm. In some embodiments, the domains of the conductive additive (such as carbon domains) have an average size of less than 100 nm, e.g., 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 40 nm, 30 nm, 20 nm, 10 nm, or smaller, or a range consisting of any of the foregoing values.

[0093] The free particles may have any combination of the characteristics described herein. For example, some embodiments relate to free particulate materials comprising free particles comprising greater than 80% by weight of grains of a metal oxide or metal phosphate electroactive phase, having a density greater than 3 g / ml, and an average particle size in the range of 1 to 30 μm. In some embodiments, the free particles have a unique internal microstructure comprising greater than 80% by weight of grains ranging from 20 nm to 300 nm in size.

[0094] In some embodiments, the novel free particulate matter of some embodiments herein comprises free particles of electroactive material, each free particle comprising greater than 80% by weight of a metal oxide electroactive phase or a metal phosphate electroactive phase, having a density greater than 3 g / ml and an average particle size in the range of 1-30 μm, the free particles comprising greater than 80% by weight of grains 20 nm to 300 nm in size. In some embodiments, the free particulate matter comprises metal oxide or metal phosphate grains in the free particles having a preferred orientation with respect to a major plane of the particle, the preferred orientation parameter being greater than 1.02 or less than 0.98, the free particles having an average internal porosity less than 20%, and the volumetric surface area of ​​the free particles being greater than 30 m. 2 / ml and the average aspect ratio of the free particles is greater than 1.5.

[0095] In some embodiments, the constituent particles of the free particulate matter can comprise an electroactive phase suitable for use in battery applications. For electroactive phases suitable for use in cathode materials, particularly exemplary cathode electroactive phases include LFP or other transition metal phosphates, including lithium manganese phosphate (LMP) or lithium iron manganese phosphate (LMFP). Furthermore, particularly exemplary cathode active phases include disordered rock-salt lithium transition metal oxides. Without being bound by theory, one reason the aforementioned cathode active phases are particularly exemplary is that they are resistant to reduction, especially when heated in an inert or reducing atmosphere and combined with a conductive additive such as graphite or other carbonaceous materials. Other exemplary cathode active phases include lithium transition metal oxides such as LCO, NMC, NCA, or LiMn2O4. In some useful embodiments, the constituent particles of the free particulate matter further comprise a conductive additive.

[0096] Further examples of specific embodiments of electroactive free particulate material include those consisting essentially of composite free particles comprising an electroactive phase and a conductive additive, wherein the electroactive phase grains are less than 200 nm in size and the active phase grains are preferentially arranged in active phase intergranular layers each having a thickness less than 500 nm. In embodiments where the free particles have a flake shape, the active phase intergranular layers are parallel to the basal plane of the flake. In some embodiments, the conductive additive is present between the electroactive phase intergranular layers, forming thin conductive additive layers between the electroactive phase intergranular layers having a thickness less than 100 nm. In some embodiments, the conductive additive can be present between the electroactive phase intergranular layers, forming small conductive additive domains between the electroactive phase intergranular layers having a size less than 100 nm. In some embodiments, the small conductive additive domains can be approximately spherical in shape.

[0097] In particularly advantageous embodiments of electroactive free particulate matter, LFP is the electroactive phase and a carbonaceous material, such as graphite, is the conductive additive. In such embodiments, weight ratios of LFP / carbonaceous material between 99.5:0.5 and 95:5 are particularly useful. A particularly useful embodiment of electroactive free particulate matter is a free particulate matter consisting essentially of LFP / carbonaceous material composite free particles, where the LFP consists of crystalline grains between 50 nm and 200 nm in size that are preferentially arranged in LFP intergranular layers that are less than 500 nm thick. In some embodiments of electroactive free particulate matter, the conductive additive is graphite and is present between the LFP intergranular layers. In some embodiments of electroactive free particulate matter, the LFP grains may be preferentially oriented relative to the LFP intergranular layers in the

[0101] direction and have a preferential orientation parameter of less than 0.98, less than 0.97, less than 0.96, less than 0.95, less than 0.94, less than 0.93, or even smaller. In some embodiments of the electroactive free particulate material, the LFP may have low lattice strain, less than 1%, less than 0.5%, less than 0.1%, or even less. It is believed that such low lattice strain values ​​indicate high crystallinity and allow for greater lithium diffusion within the LFP grains. Without being bound by theory, it is further believed that the preferential orientation of the LFP allows for rapid diffusion from the interior of the LFP grains to the grain boundaries, and that the presence of carbon between the LFP intergranular layers allows for rapid lithium diffusion and electrical conduction between the intergranular layers. In such embodiments of the electroactive free particulate material, the free particles comprising the particulate material may have a flake shape, an ellipsoidal shape, an oval shape, a potato shape, or a roughly spherical shape. An example of this embodiment is an LFP / carbon free particulate material in which the LFP / carbon weight ratio is 98:2 and the free particulate material BET surface area is 8 m 2 / g, the internal porosity of the free particles comprising the free particulate material is less than 2%, the average LFP grain size is 50 nm to 200 nm, the LFP crystallographic distortion is less than 0.1%, the LFP grains are preferentially arranged in LFP intergranular layers that are less than 500 nm in thickness, carbon is present between the LFP intergranular layers, the LFP grains have a preferred orientation in the

[0101] direction relative to the LFP intergranular layers and relative to the major planes of the free particles, the LFP grains have a preferential orientation parameter that is less than 0.98, and the free particles comprising the free particulate material have a characteristic flake morphology with a flake width of 10 μm to 20 μm and a flake thickness of 2 μm to 5 μm. As an example of another embodiment, all of the above aspects of the LFP / carbon free particulate material are the same, except that the free particles have a substantially oblong or potato shape with an average particle size of 5 μm to 30 μm.

[0098] The flake particulate material is greater than 80% by weight LiFePO4, has a density greater than 3 g / ml, an average flake diameter in the range of 5-25 μm, an average thickness in the range of 0.1-5 μm, an average aspect ratio of at least 5, and surprisingly, has a particle size of 8 m. 2 / g or even less than 6m 2 The flake free particles may also have a surface area of ​​less than 1 / g. Furthermore, in embodiments of such flake free particulate materials, the LiFePO4 may be comprised of grains having an average size of less than 0.3 μm. Furthermore, such particulate materials may include carbon, such as graphite. In some embodiments, the presence of graphite in the flake free particulate material may be detected by the presence of one or more XRD peaks characteristic of graphite, particularly the graphite (002) peak, in the XRD pattern. Furthermore, such flake free particles may have curvatures with radii of curvature ranging from 10 μm to 100 μm. As demonstrated in the examples below, positive electrodes incorporating LFP-graphite composite flake free particulate materials can be fabricated at desired loadings and have been found to achieve excellent coating densities at low calendering pressures while also exhibiting excellent electrochemical performance.

[0099] Those skilled in the art will appreciate that the methods of some embodiments herein can be used to produce other similarly unique and useful materials, particularly cathode and anode free particulate matter comprising an anode or cathode electroactive phase. Exemplary electroactive anode phases for use in Li-ion batteries include graphite, LiTiO, and LiTiO. 12 , silicon, silicon-carbon composites, silicon alloys, silicon suboxides, and combinations thereof. Exemplary electroactive positive electrode phases for use in Li-ion batteries include LCO, NMC, LFP, and LiMn2O4, and combinations thereof. Anode and cathode electroactive phases for use in Na-ion batteries may also be employed. Particularly useful embodiments of cathode and anode free particulate matter include those in which the anode or cathode electroactive phase or phases comprise greater than 80%, greater than 90%, greater than 95%, greater than 98%, greater than 99%, or even 100% of the free particulate matter composition, or any range between the aforementioned values.

[0100] In other particularly useful embodiments of electroactive free particulate matter, NMC is the active phase, and the free particulate matter composition does not include conductive additives. In some embodiments, the NMC grains may be preferentially oriented in the

[0110] direction relative to the major planes of the NMC free particles, with a preferred orientation parameter greater than 1.02, greater than 1.03, or even greater. In some embodiments, the NMC may have low lattice distortion, less than 1%, less than 0.5%, less than 0.1%, or preferably even less.

[0101] Further embodiments include positive and negative flake free particulate materials consisting of flake free particles comprising anode or cathode electroactive phase in the form of grains. Some embodiments include anode or cathode electroactive phases having an average grain size of less than 300 nm, less than 150 nm, or less than 100 nm. In some embodiments, the crystallographic direction of the grains is preferentially oriented relative to the flake orientation.

[0102] Some embodiments include positive and negative electrode free particulate matter, in which the free particles comprise a negative or positive electrode electroactive phase and a conductive additive. Exemplary conductive additives include carbon and titanium nitride. The carbon conductive additive may be graphitic or non-graphitic. Exemplary carbon conductive additives include graphite, carbon black, and carbon nanotubes. The conductive additive can be utilized directly as a raw particulate matter component or as a conductive precursor raw particulate matter component. In the latter case, the product particles of the MM process can include a conductive precursor, which can be further processed (e.g., by heating) to form the conductive additive. For example, conductive precursors of carbon conductive additives can include pitch, glucose, polyacrylonitrile, phenolic resins, and other materials that decompose to form carbon when heated in an inert atmosphere. The conductive additive incorporated into the free particles can aid in electrical and ionic conductivity during operation of the Li-ion battery. However, excessive carbon additives can reduce the specific capacity of the free particulate matter. Some preferred embodiments are those in which the content of the conductive additive in the free particles is between 1% and 10% by weight, between 1% and 5% by weight, between 1% and 2% by weight, or between 0.5% and 1% by weight.

[0103] Some embodiments advantageously include free particulate material having low internal porosity, which can be determined from the difference between the theoretical true density of the free particulate material and the density of the free particulate material as measured by helium pycnometry. Some preferred embodiments include free particulate material with an internal porosity of less than 5%, less than 2%, less than 1%, or even less.

[0104] Some embodiments advantageously allow for free particulate matter with a low surface area, which reduces surface reactivity with the electrolyte, thereby improving capacity retention. 2 / ml or less, 25m 2 / ml, less than 20m 2 / ml, less than 10m 2 / ml or even lower flake free particulate matter is advantageously possible with the methods disclosed herein.

[0105] In some embodiments, the loose particulate material consists essentially of flake loose particles having a flake diameter of 5 μm to 50 μm, a thickness of 0.1 μm to 10 μm, and an aspect ratio of at least 5. Desired embodiments include flake loose particulate material consisting essentially of flake loose particles having a flake diameter of 5 μm to 25 μm, a thickness of 0.1 μm to 5 μm, and an aspect ratio of at least 5. Flake loose particles having a flake diameter of 10 μm to 20 μm, a thickness of 1 μm to 2 μm, and an aspect ratio of at least 10 are particularly desirable. Furthermore, such flake loose particles may have a radius of curvature. In some preferred embodiments, the flake loose particles have a radius of curvature of less than 150 μm, less than 50 μm, or even less. Without being bound by theory, it is believed that such particles have improved flowability, allowing for easier handling and easier formation of high-density arrays during the calendering process. However, a flake radius of curvature that is too small may result in lower packing density. In some preferred embodiments, the flake radius of curvature is greater than half the flake diameter. In particular, some embodiments include flake free particulate matter having an average flake diameter of 10 μm to 20 μm and a flake radius of curvature of about 25 μm.

[0106] [Electrodes for electrochemical cells] Another aspect of the present disclosure is a unique electrode for use in electrochemical cells, such as Li-ion batteries. Such electrodes can contain the aforementioned free particulate material at practical loadings, but with unexpectedly low porosity, and can exhibit competitive or superior electrochemical performance.

[0107] In the prior art, too low a porosity of free particles can hinder electrolyte penetration into the positive electrode coating, resulting in poor battery rate performance, while too high a porosity can result in low energy density, poor electrical conductivity, and increased reactivity with the electrolyte. However, in some embodiments of the present disclosure, very dense coatings made with flake particles surprisingly do not follow these rules. Instead, high rate performance can be achieved with high-density, low-porosity coatings that typically do not perform well with conventional particles. In some embodiments, electrodes comprising flake particles with near-zero porosity and high loadings exhibit improved performance in electrochemical cells.

[0108] In some embodiments, novel electrodes for electrochemical cells can include a porous electroactive coating on a current collector, the electroactive coating comprising greater than 80% by weight of free particulate material and a binder. For example, in some embodiments, the electroactive coating comprises greater than 80%, 85%, 90%, 95%, or more by weight (or a range consisting of any of the foregoing values) of free particulate material. The free particulate material can include free particles described herein. For example, in some embodiments, the free particulate material comprises free particles, each free particle comprising greater than 80% by weight of an electroactive phase (e.g., LFP), having an average particle size in the range of 5 μm to 30 μm, and an average aspect ratio of at least 1.5.

[0109] In some embodiments, the loading of the electrode coating on the current collector is 2 mAh / cm 2 , 3mAh / cm 2 , 4mAh / cm 2 , 5mAh / cm 2 , 6mAh / cm 2, or greater, or a range consisting of any of the foregoing values. In some embodiments, the electrode coating has an electrode porosity of less than 20%, e.g., 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or a range consisting of any of the foregoing values. In some embodiments, the electrode coating may be uniquely less than 20% porous and the loading on the current collector is less than 2 mAh / cm. 2 In some embodiments, the electrode coating may further be less than 15% porous and / or the loading of the electrode coating on the current collector is greater than 3 mAh / cm 2 It may be super.

[0110] The novel free particulate matter and electrodes described above may be particularly useful in lithium-ion rechargeable batteries. For example, a lithium-ion battery may desirably include a negative electrode, a positive electrode, and an electrolyte, where the positive electrode may include one of the electroactive free particulate matter positive electrode materials described above and the negative electrode may include one of the electroactive free particulate matter negative electrode materials described above. Or, for example, a lithium-ion rechargeable battery may desirably include the low-porosity electrode described above.

[0111] In some embodiments, the positive electrode material may have a spinel structure. In some embodiments, the positive electrode material may have an olivine structure.

[0112] In some embodiments, the cathode material may have an α-NaFeO 2 structure or a similar structure with orthorhombic or monoclinic distortions.

[0113] In such electrode embodiments, the free particles therein can consist of grains having an average size of less than 300 nm. Furthermore, the free particles can include additional components such as solid conductive diluents (e.g., graphite, carbon black, carbon nanotubes), binders, or other adhesion promoters.

[0114] [Definition] Unless the context requires otherwise, throughout this specification and claims, the terms "comprise", "comprising", and the like are to be interpreted in an open and inclusive sense. The terms "a", "an", and the like are to be interpreted as meaning at least one and are not to be limited to one.

[0115] With respect to a given article, the transitional phrase "consisting essentially of" should be interpreted to limit the materials or processes specified and "not materially affect the basic and novel characteristics of the given article." For example, the phrase "NMC consists essentially of crystalline grains" should be interpreted to allow for the presence of small amounts of amorphous grains, provided that their presence does not materially affect the novel characteristics of the free particles.

[0116] As used herein, language of degree, such as the terms "approximately," "about," "generally," and "substantially," refers to a value, amount, or characteristic that approximates a stated value, amount, or characteristic that still performs a desired function or achieves a desired result. In quantitative contexts, the term "about" should be interpreted as within +5% to -5% of the stated value.

[0117] Additionally, the following definitions shall apply throughout this specification:

[0118] As used herein, the term "particulate matter" refers to a plurality of particles or agglomerates of particles.

[0119] The term "loose particles" refers to particles that are not attached or supported by template particles, and similarly, the term "loose particulate matter" refers to particulate matter that consists essentially of loose particles.

[0120] The term "template particle" refers to the nominally spherical media used during the mechanofusion step of the MM process in the preparation of free particles.

[0121] As used herein, the terms "electrochemically active phase" or "electroactive phase" or "active phase" should be interpreted as understood by those skilled in the art, but generally refer to the phase of material that undergoes electrochemical redox reactions during charging or discharging of the cell and is directly utilized to store and supply electrical energy. In the case of lithium-ion batteries, the positive electrode electroactive phase may be Li / Li, such as LiCoO, NMC, LFP, NCA, Co-free NMC, and LiMnO. + During normal cell operation at potentials above 2.5 V relative to Li + In lithium-ion batteries, the negative electrode electroactive phase is graphite, hard carbon, and Li4Ti5O 12 etc., Li / Li + During normal cell operation at potentials less than 2 V relative to Li + It is capable of reversibly electrochemically reacting with ions.

[0122] The term "inactive phase" should be interpreted as understood by those skilled in the art, but generally refers to a phase of material that does not undergo oxidation-reduction reactions during charging or discharging of the cell.

[0123] The terms "electroactive material", "active material", "electroactive particulate matter", or "active particulate matter" refer to particulate matter whose constituent particles comprise at least 80% by weight of an active phase.

[0124] The terms "electroactive free particulate matter" or "active free particulate matter" refer to free particulate matter in which the constituent free particles comprise at least 80% by weight of an active phase.

[0125] The terms "electroactive positive electrode material" or "positive electrode material" refer to an electroactive material that comprises at least 80% by weight of a positive electrode electroactive phase.

[0126] The terms "electroactive negative electrode material" or "negative electrode material" refer to an electroactive material that comprises at least 80% by weight of a negative electrode electroactive phase.

[0127] The term "grain" refers to a region within a material that is single crystal. Grains are also referred to as "crystallites" by those skilled in the art, and these terms are used interchangeably herein. The presence of grains within a material can be determined from an X-ray diffraction pattern obtained using a conventional laboratory X-ray diffractometer with Cu-Kα radiation in the 10°-80° (2θ) range. The presence of grains within a material is indicated by the presence of X-ray diffraction peaks in the material's X-ray diffraction pattern that are characteristic of crystalline materials (e.g., peaks with a half-width less than about 3° (2θ)). A material having an X-ray diffraction pattern consisting essentially of X-ray diffraction peaks characteristic of crystalline materials is indicative of a material that is essentially composed of grains. A material having an X-ray diffraction pattern in which peaks corresponding to a particular phase or component of a material consisting essentially of X-ray diffraction peaks characteristic of crystalline materials is indicative of a phase or component within a material that is essentially composed of grains.

[0128] The term "intragrain layering" refers to layering that occurs inside the grain due to the crystallographic arrangement of atoms within the grain.

[0129] The terms "intergranular layered" or "intergranularly arranged" refer to an arrangement of grains within a free grain such that the grains are statistically arranged in a layered pattern parallel to the major planes of the free grain. Intergranular layered ordering is indicated by a preferential orientation of grains within the grain having a preferred orientation parameter greater than 1.02 or less than 0.98.

[0130] The "major plane" of a free particle corresponds to the plane within the free particle that is parallel to its largest cross-sectional area.

[0131] The term "particle diameter" or "particle size" refers to the diameter of a sphere having the same volume as the particle in question. The term "average particle diameter" or "average particle size" refers to the average particle diameter of the particles comprising the particulate material.

[0132] The term "particle width" or "flake diameter" also refers to the diameter of a circle having the same area as the maximum cross-sectional area of ​​the particle.

[0133] The term "average flake diameter" or "average particle width" refers to the average flake diameter or particle width of the particles comprising the particulate material.

[0134] The term "particle thickness" or "flake thickness" also refers to the length of the axis of a cylinder having the same volume as the particle in question and a diameter equal to the particle width of the particle in question.

[0135] The "aspect ratio" of a grain is calculated by dividing the grain width by the grain thickness.

[0136] The "average aspect ratio" of a particulate material refers to the average of the aspect ratios of all particles, including particulate material having a particle width that is greater than 1 μm.

[0137] The term "flake particle" or "flake" refers to a thin particle (typically broken from a larger piece) defined as being of substantially uniform thickness, having a surface (face) substantially perpendicular to the thickness, and having an aspect ratio of at least 5. The faces of the flakes may also be curved, with a radius of curvature parallel to the thickness direction. As used herein, the term "substantially" refers to a set of values ​​that can be considered substantially equivalent to a nominal value if the standard deviation in their distribution is less than 10% of the mean.

[0138] The terms "potato-shaped" or "potato morphology" refer to particles having an aspect ratio of 1.5 to 5.

[0139] The term "internal porosity" refers to the void space (or pore volume) that is completely enclosed within a material. When applied to a particulate material, the term "internal porosity" refers to all of the void space (or pore volume) that is completely enclosed within the individual particles that make up the particulate material. The internal porosity of a material is often expressed as a percentage quantity that refers to the fraction of the total volume occupied by the material that is related to the porosity of the material, and can be expressed as: Internal porosity (%) = (pore volume) ÷ (total volume of material) × 100% where the total volume of the material includes the pore volume. In particulate samples, the total volume of the material does not include the void space between the particles.

[0140] The term "electrode porosity" refers to the void space within an electrode coating that corresponds to the external volume of the electrode coating, and is determined by measuring its external dimensions (e.g., with a micrometer) minus the volume of the electrode calculated from the true density of its components. Electrode porosity is often expressed as a percentage as follows: Electrode porosity (%) = ((electrode coating volume measured from its outer dimensions) - (electrode coating volume determined from the true density of its components)) / (electrode coating volume measured from its outer dimensions)

[0141] The term "preferential orientation" refers to an arrangement of crystallites with non-random alignment of their crystal axes. The preferred orientation of a particulate material sample can be quantified as a "preferential orientation parameter" determined using the Dollase and March model applied to the powder X-ray diffraction pattern of the sample measured on a flat sample holder, as described in W.A. Dollase, "J. Appl. Cryst.", 1986, 19, pp. 267-272, and A.C. Larson and R.B. Von Dreele, "General Structure Analysis System (GSAS)," Los Alamos National Laboratory Report LAUR, 2004, pp. 86-748. The preferred orientation parameter is equal to 1 in a sample without preferred orientation. In plate-shaped crystals aligned so that the plate planes are preferentially parallel to the flat sample holder, the preferred orientation parameter is less than 1. In needle-shaped crystals aligned so that the long axes of the needles are preferentially parallel to the flat sample holder, the preferred orientation parameter is greater than 1. The "preferential orientation direction" is expressed in terms of the Miller indices [hkl] of the crystallographic plane of the preferred orientation. In plate-shaped crystals arranged so that the plate faces are preferentially aligned parallel to the flat sample holder, the preferred orientation direction is the Miller indices [hkl] of the crystallographic plane parallel to the crystallographic plane corresponding to the face of the plate crystal. In needle-shaped crystals arranged so that the long axes of the needles are preferentially aligned parallel to the flat sample holder, the preferred orientation direction is the Miller indices [hkl] of the crystallographic plane perpendicular to the long axes of the needles.

[0142] "Impact milling" is a process of particle comminution by impact of particles with other particles using a milling device or milling media. Impact milling can be performed with particles in a gas or vacuum (dry impact milling), or with a gas such as air or an inert gas, including nitrogen. Impact milling can also be performed with particles in a liquid (wet impact milling). However, dry impact milling methods are generally preferred over wet impact milling methods because they avoid additional steps associated with wet impact milling, such as filtration or drying. Impact milling processes that do not use milling media are preferred because they reduce the possibility of damaging the flakes after separation from the template particles. Some impact milling methods include jet milling, pin milling, and centrifugal impact milling. On a small laboratory scale, centrifugal impact milling can be performed using a kitchen blender or coffee grinder. Impact milling methods that include a separation process to remove and collect loose flakes as they are generated are particularly desirable. In some instances, the separation process occurs after the impact milling process is complete. Suitable separation processes include cyclone air classification and sieving, in which case the free particulate matter consisting essentially of free particles can be recovered to form the product free particulate matter.

[0143] The term "primary particle" refers to a particle consisting of one domain or multiple domains that are strongly bonded together. Primary particles are not easily broken down into smaller components by dry milling.

[0144] The term "secondary particles" refers to agglomerates of weakly bound primary particles.

[0145] The term "negative electrode" refers to the electrode where oxidation reactions occur when a metal-ion cell is discharged. In a lithium-ion cell, the negative electrode is the electrode that delithiates during discharge and lithiates during charge.

[0146] The term "cathode" refers to the electrode where a reduction reaction occurs when a metal-ion cell is discharged. In a lithium-ion cell, the cathode is the electrode that is lithiated during discharge and delithiated during charge.

[0147] The term "metal-ion cell" or "metal-ion battery" refers to alkali metal-ion cells, including lithium-ion cells and sodium-ion cells.

[0148] The term "half-cell" refers to a cell having a working electrode and a metal counter / reference electrode. A lithium half-cell has a working electrode and a lithium metal counter / reference electrode.

[0149] As used herein, the terms "mechanofusion" and / or "mechano-fusing" (also referred to as "MF") refer to the mechanical fusing of small particles, such as template particles and feedstock particles, to larger particles to form a coating. For example, mechanofusion can fuse materials through the use of high shear and / or high pressure fields. For example, mechanofusion can be a dry process that does not use solvents. Mechanofusion can be used to coat template particles with feedstock particles.

[0150] The following examples illustrate aspects of some embodiments and should not be construed as limiting the disclosure in any way. Those skilled in the art will readily recognize that other variations in the methods and materials produced herein are possible. [Example]

[0151] In accordance with some embodiments herein, exemplary loose particulate materials of either LiFePO4 or NMC were prepared using dry mechanofusion and impact milling. For comparative purposes, other particulate materials were also prepared. Various properties of these particulate materials were determined and are presented below. Additionally, electrodes and electrochemical cells were fabricated using these particulate materials. Cell performance results obtained from the electrochemical cells are also presented below.

[0152] [Preparation and analysis methods used] [Mechanofusion Processing] Mechanofusion processes were performed using a modified AM-15F Mechanofusion System (Hosokawa Micron Corporation, Osaka, Japan). This machine was modified by replacing the standard stainless steel chamber, scraper, and press head with identical hardened steel components to reduce wear. Unless otherwise noted, mechanofusion processes were performed with a press head spacing of 1.4 mm and a scraper spacing of 0.5 mm. The chamber had an inner diameter of 15 cm. The gas atmosphere used during mechanofusion processes was air unless otherwise indicated. Unless otherwise indicated, mechanofusion processes were applied to a mixture of raw material particles and template particles. The template particles used were ZrO2 spheres (50 μm, Glen Mills). SEM images of these template particles are shown in Figure 2.

[0153] [Impact milling] Unless otherwise stated, impact milling was performed using a coffee grinder (CBG110S / BLACK+DECKER) as follows: 80 g of material was placed in the coffee grinder and pulse-milled for 15-20 pulses (1 second grinding time for each pulse).

[0154] [BET surface area] The specific surface area of ​​the sample materials was determined by the single-point Brunauer-Emmett-Teller (BET) method using a Nova 4200e specific surface area and pore size analyzer.

[0155] [X-ray diffraction] X-ray diffraction (XRD) pattern analysis was performed using a Rigaku Ultima IV diffractometer equipped with a Cu Kα X-ray source, a diffracted beam monochromator, and a scintillation detector. Each XRD pattern was collected from 10° to 80° (2θ) in 0.05° increments, with each step taking 3 seconds. The lattice constants, atomic positions, preferred orientation directions, preferred orientation parameters, X-ray peak positions, and full width at half maximum (FWHM) values ​​were determined by Rietveld refinement using LHPM refinement software (A Computer Program for Rietveld Analysis of X-Ray and Neutron Powder Diffraction Patterns, Australian Nuclear Science and Technology Organization, Lucas Heights Research Laboratories, February 2000). The Rietveld refinement of the LiFePO4 phase was performed using the space group Pnma, with Li occupying the 4a site and P and Fe each occupying a unique 4c site. Oxygen atoms are located in three unique sites, labeled O1, O2, and O3; O1 and O2 are 4c sites, and O3 is an 8d site. The lattice parameters and arbitrary atomic fraction coordinates were allowed to vary within the Wyckoff positions and were left variable during refinement. The average crystallite size and average lattice distortion of the different phases were determined from the X-ray peak positions and FWHM values ​​obtained from Rietveld refinements for peaks whose FWHM was greater than the instrumental broadening error (0.1°) using the Williamson-Hall method, as described in Emil Zolotoyabko, "Basic Concepts of X-Ray Diffraction," John Wiley & Sons, February 2014.

[0156] The grain size was determined by applying the Scherrer equation to the maximum X-ray diffraction peak of the particulate material.

[0157] [SEM and cross-sectional SEM] The material morphology was analyzed using a scanning electron microscope (SEM) (JEOL JSM-IT200 InTouchScope Scanning Electron Microscope, JEOL Ltd., Tokyo, Japan). Broad ion beam (BIB) cross-section preparation of the SEM samples was performed using an argon ion beam in a cross-section polisher (JEOL IB-19530 CP Cross-Section Polisher, JEOL Ltd., Tokyo, Japan). Focused ion beam (FIB) cross-section preparation of the SEM samples was performed using a Hitachi FB-2000A FIB System equipped with a liquid gallium source. Grain size, grain width, and average grain thickness were determined from the dimensions of at least 50 randomly selected grains during SEM observation. The average aspect ratio was determined from the dimensions of at least 50 randomly selected grains with a grain width greater than 1 μm during SEM observation.

[0158] [Electrode coating characteristics] The electrode coating thickness was determined by measuring the total electrode thickness (using a Mitutoyo 293-340 precision micrometer) and then subtracting the electrode current collector thickness (also measured using a Mitutoyo 293-340 precision micrometer). The electrode load was measured using a 1.3 cm2 piece cut from the electrode using a precision die. 2 The coating weight of the electrode disk was then determined by subtracting the weight of the current collector of the same area from the electrode weight. This allowed the determination of the coating weight per area, the amount of electroactive material per unit area (loading), and the coating density. The electrode porosity was determined from the electrode coating thickness (t) and the theoretical zero-porosity electrode coating thickness (t°, calculated at the same electrode loading using the true density) as follows: Electrode porosity (%)=(tt°) / t×100%

[0159] [Electrode preparation] Sample electrodes for laboratory testing were prepared from slurries consisting of particulate material, carbon black (Super C65, Imerys Graphite and Carbon), and polyvinylidene fluoride binder (PVDF) (weight ratios shown in Table 1) in 1-methyl-2-pyrrolidone (NMP, Sigma-Aldrich, 99.5% anhydrous). The slurries were mixed using a high-shear mixer for a total time of 1800 seconds (30 minutes) and then coated onto aluminum foil using a coating bar with a 0.016-inch gap. The electrodes were then dried in air at 120 °C for 1 to 1.5 hours. The electrodes were compressed using a calender (DPM Solutions, Hebbville, NS) equipped with two 6-inch diameter heated rolls and an adjustable nip. Calendering was performed at incrementally smaller nip heights until the minimum nip height before electrode delamination occurred was reached (the nip height at which electrode coating delamination occurred was determined by successively calendering sections of the electrode until electrode coating delamination occurred). The dried and calendered electrodes were cut into 1.3 cm disks and heated overnight at 120°C under vacuum before cell fabrication. The electrode loading (i.e., electroactive particulate matter mg / cm) was determined. 2 ) are listed in Table 1.

[0160] [Table 1]

[0161] [Cell fabrication and testing] To evaluate various materials as electrode materials for Li-ion cells, laboratory lithium half-cells were fabricated and tested. Sample electrodes were assembled into 2325-type coin cells. The cell contents consisted of (in order of construction): a copper spacer, a lithium foil (99.9%, Sigma-Aldrich) counter / reference electrode, one polypropylene / polyethylene / polypropylene trilayer separator (Celgard 2300, Celgard, LLC, North Carolina, USA), a polypropylene blown microfiber (BMF) membrane (3M Company), the sample electrode, and an aluminum spacer. (Note: As is known to those skilled in the art, results from these lithium test half-cells can reliably predict the performance of electrode materials in lithium-ion batteries.) During cell assembly, the sample electrode, trilayer separator, BMF membrane, and lithium foil were thoroughly wetted with an electrolyte solution of 1 M LiPF6 (BASF) in a solution of ethylene carbonate, diethyl carbonate, and fluoroethylene carbonate (all from BASF) in a volume ratio of 3:6:1. Coin cell assembly was performed in an Ar gas-filled glove box. Cells fabricated with the LFP sample electrode were galvanostatically cycled between 2.5 V and 3.65 V at 30.0 ± 0.1 °C according to three test protocols designated P1, P2, and P3. In all test protocols, the C-rate was defined as the current required to fully charge or discharge the active material in 1 hour, based on the theoretical active material capacity. For LFP, the C-rate was based on the theoretical capacity of LFP of 170 mAh / g. For NMC622, the C-rate was based on the theoretical capacity of NMC622 of 200 mAh / g. In Protocol 1 (P1), the first cycle was performed at a rate of C / 20, and subsequent cycles were performed at a constant rate of C / 10. In Protocol 2 (P2), the first cycle was performed at a rate of C / 20, and subsequent cycles were performed at cycle rates that increased from 0.1C, 0.2C, 0.5C, 1C, 2C, 5C to 10C every 5 cycles, while keeping both the charge and discharge rates equal to each other.Protocol 3 (P3) was the same as P2, except that after the first C / 20 cycle, the charge cycle maintained a constant 0.1C rate, and only the discharge rate was increased every 5 cycles from 0.1C, 0.2C, 0.5C, 1C, 2C, 5C to 10C. All cells were cycle tested using a Maccor Series 4000 Automated Test System.

[0162] [Comparative example (CE1)] LiFePO4 (denoted as LFP) particulate material (P198-S13, BTR New Materials Group Co., Ltd., China) was used as is (denoted as "CE1 particulate material"). Figure 3 shows an SEM image of the CE1 particulate material, which consists of primary particles mainly ranging in size from 0.1 μm to 1 μm. Some of the primary particles are aggregated into secondary particles with diameters of approximately 5 μm to 7 μm. The BET surface area of ​​the CE1 particulate material is 11.69 m. 2 / g, and the density of the CE1 particulate matter was measured to be 3.507 g / ml, which corresponds to a volumetric surface area (VSA) of 41.0 m for the CE1 particulate matter. 2 / ml. Figure 4 shows the X-ray diffraction (XRD) pattern of the CE1 particulate material. It is typical of highly crystalline LiFePO4, with an ordered olivine structure indexed to the orthorhombic Pnma space group. The unit cell parameters, atomic positions, and preferred orientation values ​​obtained from the Rietveld refinement of the CE1 particulate material are listed in Table 2. No preferred orientation was detected in any crystallographic direction in this sample (i.e., the preferred orientation parameter was equal to 1). From the X-ray diffraction pattern, the average LiFePO4 grain size and strain were determined to be 206 nm and 0.04%, respectively.

[0163] [Table 2]

[0164] Electrodes in which CE1 particulates served as the electroactive particulates were formulated according to Table 1. This coating allowed for an electrode porosity of 2.164 g / cm, corresponding to 31%, before delamination of the electrode coating occurred. 3 Figure 5 shows an SEM image of the cross section of the electrode coating of CE1, which contains randomly packed LFP particles with the same particle size distribution as the original CE1 particulate material, including carbon black and porosity present in the interparticle spaces.

[0165] Lithium half-cells were fabricated using the electrode coating of CE1 as the working electrode. Figure 6 shows the voltage curve of one of these cells cycled according to Protocol P1. The voltage curve is typical of a conventional LFP-based cathode. The cell had an initial coulombic efficiency (ICE) of 98.7%. At an average discharge voltage of 3.36 V, a reversible capacity of 161.26 mAh / g was obtained. Combined with the electrode coating density listed in Table 1, this corresponds to a coating energy density of 1174 Wh / L.

[0166] Figure 7 shows the polarization of the same cell shown in Figure 6 plotted as a function of cycle number. At 50 cycles, an average polarization of 0.12 V was achieved. Figure 8 shows the capacity and coulombic efficiency (CE) of the same cell shown in Figure 6 plotted as a function of cycle number. The cell had a capacity loss of 0.97% and an average CE of 0.997 from cycles 6 to 50.

[0167] [Example (IE1)] LFP / carbon composite flake free particulate material was synthesized as follows: 10.85 g of CE1 particulate material, 0.22 g of natural graphite (Grade 230U, Asbury Graphite Mills, Kittanning, PA), and 225 g of ZrO2 spheres (50 μm, Glen Mills), which served as template particles, were mechanofused at 1000 rpm for 20 minutes. After 20 minutes of mechanofusion, a uniform coating of unheated LFP / carbon composite was achieved on the ZrO2 spheres, as shown in Figure 9. The coated ZrO2 spheres were then impact milled as described above. Figure 10 shows an SEM image of the coated ZrO2 spheres after impact milling. During the impact milling process, most of the unheated LFP / carbon composite coating on the ZrO2 spheres peeled off, resulting in the formation of a mixture of partially coated spherical ZrO2 template particles and unheated LFP / carbon composite flake free particulate matter.

[0168] The unheated LFP / carbon composite flake free particulate material was separated from the partially coated ZrO2 spheres using a 38 μm sieve. Figure 11 shows an SEM image of the unheated LFP / carbon composite flake free particulate material. More than 95% of the flake free particulate material is in the form of free particles with a characteristic flake morphology, with flake widths ranging from 10 to 20 μm and flake thicknesses ranging from 2 to 5 μm. Figure 12 shows the XRD pattern of the unheated LFP / carbon composite flake free particulate material. It contains peaks characteristic of LFP, but the peaks are broader than those of the initially received crystalline LFP particulate material, indicating a reduction in grain size and the occurrence of defect formation in the structure. In addition to the peaks from LFP, the XRD pattern of the unheated LFP / carbon composite flake free particulate material also contains a peak from the graphite (002) reflection at approximately 26.4°, reflecting the presence of graphitic carbon incorporated into the flake free particles.

[0169] The unheated LFP / carbon composite flake free particulate material was heated at 650 °C for 10 hours in a mixed gas flow of 95% Ar and 5% H2 to obtain the final LFP / carbon composite flake free particulate material. An SEM image of the resulting IE1 free particulate material is shown in Figure 13. Its constituent particles maintain the characteristic flake morphology of the unheated LFP / carbon composite flake free particulate material, with flake diameters in the range of 10–20 μm, flake thicknesses in the range of 1–2 μm, and a corresponding average aspect ratio of approximately 10. The IE1 flake free particulate material also exhibits a radius of curvature of approximately 25 μm, imparted by the 50 μm template particle. The BET surface area of ​​the IE1 flake free particulate material is 5.23 m. 2 / g, and the density of the IE1 flake free particulate matter was measured to be 3.468 g / ml. 2 / ml of IE1 flake free particulate matter VSA.

[0170] By comparing the measured density of IE1 with the theoretical true density, the internal porosity of IE1 was determined to be approximately 1.1%. Figure 14 shows the XRD pattern of IE1 flake free particulate material. Compared to the sample before heating, the XRD peaks narrowed, indicating that the heating process resulted in grain growth and the disappearance of crystalline defects. In addition to the peak from LFP, the XRD pattern of IE1 flake free particulate material contains a peak from the graphite (002) reflection at approximately 26.4°, reflecting the presence of graphitic carbon incorporated into the flake free particles.

[0171] The unit cell parameters, atomic positions, and preferred orientation values ​​obtained from the Rietveld refinement of the IE1 flake free particulate material are listed in Table 2. The XRD pattern is characteristic of highly crystalline LiFePO4, with an ordered olivine structure indexed to the orthorhombic Pnma space group and lattice parameters and atomic positions nearly identical to those of material made according to CE1. From the X-ray diffraction pattern, the average LiFePO4 grain size and strain were determined to be 160 nm and 0.05%, respectively.

[0172] The MM process and subsequent heating resulted in a reduction in grain size compared to the CE1 sample, which is believed to be beneficial for improving lithium diffusion in the LFP and resulting in increased rate performance. At the same time, lattice distortion remained very low without any obvious changes as a result of the MM process, suggesting that a native crystalline structure was achieved. Compared to the CE1 sample, the relative XRD peak intensity ratio of IE1 was significantly different. Rietveld refinement revealed that this was due to the preferential orientation of the LFP grains, with a preferred orientation direction of

[0101] and a preferred orientation parameter of 0.93. This indicates that the LFP grains constituting the IE1 flake free particle are in the form of platelets arranged in intergranular layers within the IE1 flake free particle, such that the planes of the LFP platelets are preferentially aligned with the major planes of the flake free particle.

[0173] Figure 15 shows an SEM image of a single IE1 flake-free particle whose surface was etched using a focused gallium ion beam (FIB). In this image, the flake-free particle is oriented so that its basal plane is parallel to the plane of the page. Etching this flake-free particle from above with a gallium ion beam exposes the internal intergranular layers, where the intergranular layers are parallel to the basal plane of the flake-free particle. Figure 16 shows an SEM image of a single IE1 flake-free particle cut in cross section with a broad argon ion beam, with the cross section perpendicular to the basal plane of the flake-free particle. The image in this figure is of the surface of this cross section. While the particle is mostly solid, several closed pores are visible. Many of the closed pores are very small (50 nm) voids, surrounded by bright boundaries in the secondary electron image. These small voids are believed to be formed by the evaporation of carbon in the sample during the argon ion milling process. Therefore, they reveal the location of carbon in the sample.

[0174] The arrangement of voids in the cross section shown in Figure 16 is not random, but rather suggests an intergranular layered microstructure. The void lines that penetrate the grain in this image are highlighted in Figure 17. This microstructure can be attributed to the MM process, in which the template grain is coated with LFP and graphite particles, while this coating is subjected to high shear forces, shearing and smoothing the graphite and LFP particles along the template grain surface. XRD results indicate that in this process, the LFP shears primarily along the (101) plane. This mechanism would result in continuous graphite and LFP intergranular layers that are parallel to the basal plane of the free flakes. During subsequent heating, the free LFP particles crystallize, causing grain growth and partial destruction of the intergranular layered microstructure. This grain growth is evident in the upper part of the image shown in Figure 16. This intergranular layered microstructure explains the layered appearance of the FIB-etched grain shown in Figure 15 and is due to the different erosion rates of the graphite and LFP intergranular layers during the etching process. From Figure 16, the spacing between intergranular layers in the intergranular layered microstructure varies in the range of about 100 to 350 nm.

[0175] Electrodes in which IE1 flake free particulate matter served as the electroactive positive electrode material were formulated according to Table 1. This coating allowed for an electrode porosity of 2.719 g / cm, corresponding to 14%, before delamination of the electrode coating occurred. 3 An electrode coating density of 1000 nm was achieved. FIG. 18 shows an SEM image of a cross section of the electrode coating of IE1. It contains carbon black and LFP / carbon composite flake free particulate matter, including porosity present in the spaces between the particles. The planes of the LFP / carbon composite flake free particulate matter are preferentially oriented parallel to the electrode current collector. Without being bound by theory, it is believed that this preferential orientation may be responsible for the high electrode coating density observed for this electrode.

[0176] Lithium half-cells were fabricated using the electrode coating of IE1 as the working electrode. Figure 19 shows the voltage curve of one of these cells cycled according to P1. The voltage curve is typical of an LFP-based cathode. The cell had an ICE of 99.6%. At an average discharge voltage of 3.38 V, a reversible capacity of 161.65 mAh / g was obtained. Combined with the electrode coating density listed in Table 1, this corresponds to a coating energy density of 1492 Wh / L.

[0177] Figure 7 shows the polarization of the same cell shown in Figure 19 plotted as a function of cycle number. At 50 cycles, an average polarization of 0.08 V was achieved. Figure 8 shows the capacity and CE of the same cell shown in Figure 19 plotted as a function of cycle number. The cell had a capacity loss of 0.97% and an average CE of 0.999 from cycles 9 to 50.

[0178] Table 1 lists some of the properties of the electrodes prepared according to Examples CE1 and IE1. The electrode prepared according to Example IE1 achieved a 25% higher electrode coating density than the electrode prepared according to Example CE1. This is believed to be due to the improved packing of the IE1 flake free particulate material.

[0179] Table 3 lists some electrochemical performance characteristics of the CE1 particulate material and the IE1 flake free particulate material characterized in cells cycled according to P1. Due to the increased electrode density, the electrode fabricated according to Example IE1 has a coating energy density 27% greater than the electrode fabricated according to Example CE1. Furthermore, the electrode fabricated according to Example IE1 has a significantly higher average CE than the electrode fabricated according to Example CE1. This is believed to be due to the low surface area of ​​the IE1 flake free particulate material, which is 55% lower than the surface area of ​​the CE1 particulate material. This lower surface area is believed to result in less electrolyte degradation at the surface of the IE1 flake free particulate material. Despite the low surface area of ​​the IE1 flake free particulate material, it surprisingly had a significantly lower average polarization. This is believed to be due to improved electronic conductivity of the IE1 flake free particulate matter due to the presence of incorporated carbon in these particles, improved electronic conductivity between the IE1 free particles in the electrode coating due to a larger surface contact area (due to the flake shape of the free particles and preferential orientation of the electrode), and improved lithium ion diffusion (believed to be facilitated by diffusion at the carbon / LFP grain boundaries).

[0180] [Table 3]

[0181] Lithium half-cells were also fabricated using the CE1 and IE1 electrode coatings as the working electrodes. These cells were cycled according to P2. Figure 20 shows the capacities of these cells at various rates. The first charge was performed at a rate of C / 20, resulting in a capacity of 155.9 mAh / g and an ICE of 99.9% for CE1, and a capacity of 150.97 mAh / g and an ICE of 96.4% for CE1. Subsequent cycles were performed at various rates (C / 10, C / 5, C / 2, 1C) for five cycles each, both charge and discharge without hold. Table 4 summarizes the electrochemical rate performance characteristics of the CE1 and IE1 particulate materials.

[0182] [Table 4]

[0183] [Example (IE2)] LFP / carbon free particulate material (IE2) containing potato-shaped free particles was synthesized using the same method as described for IE1, except that the template particles were reused from the previous synthesis of IE1. As a result of their use in the previous synthesis of IE1, these template particles had residual LFP / carbon material on their surfaces that was not removed by the impact milling process. This resulted in the formation of a thicker LFP / carbon coating on the template particles after mechanofusion treatment. Figure 21 shows an SEM image of the resulting IE2 free particulate material. Some of the particles have a flake-like morphology. However, most of the particles are potato-shaped. The aspect ratio of the particles ranged from approximately 1 to 5, with an overall average aspect ratio of 2.6. The particle diameter ranged from approximately 0.5 to 25 μm, with the sample having an overall average particle size of approximately 10 μm. The density of the IE2 particulate material was measured to be 3.48 g / ml. The BET surface area of ​​IE2 free particulate matter is 3.620 m 2 / g, and 12.6m 2 / ml of VSA.

[0184] Figure 22 shows the XRD pattern of the IE2 free particulate material. The unit cell parameters, atomic positions, and preferred orientation values ​​obtained from Rietveld refinement of the IE2 free particulate material are listed in Table 2. The XRD pattern is characteristic of highly crystalline LiFePO4, which has an ordered olivine structure indexed to the orthorhombic Pnma space group. Rietveld refinement revealed that the LFP grains of the IE2 free particulate material had a preferred orientation with a preferred orientation direction of

[0101] and a preferred orientation parameter of 0.93. This indicates that the LFP grains constituting the IE2 free particles are in the form of platelets arranged in intergranular layers within the IE2 free particles, such that the planes of the LFP platelets are preferentially aligned with the major planes of the IE2 free particles. Rietveld refinement also revealed that the LFP grains had an average grain size of 145 nm, and the sample had a crystallographic strain of 0.04%.

[0185] An electrode was fabricated in a similar manner to Example IE1, except that IE2 was used as the electroactive positive electrode material. The electrode coating was subjected to calendering, resulting in 30% electrode porosity. Figure 23 shows a cross-sectional image of this electrode. From this cross-section, it can be seen that the majority of the particles have a substantially oblong or potato-like shape. Intergranular layering is also evident in these particles. In fact, the particles are nearly identical to IE2 in all respects, except for the different external dimensions, resulting in a potato-like shape instead of a flake-like shape and a lower VSA. Because the majority of the particles in IE2 are not flake-like, the preferential particle alignment is significantly reduced in this electrode compared to the electrode fabricated from IE1. This likely explains why the IE2 electrode had a higher electrode porosity than the IE1 electrode.

[0186] Cells were constructed with the IE2 electrode and cycled according to P3. For comparison, additional cells using the CE1 electrode were also cycled according to P3. Figure 24 shows the capacity of these cells versus cycle number. The first cycle discharge capacity and average discharge capacity obtained at each test discharge rate are listed in Table 5. IE2 has nearly the same rate capability as CE1, despite the particle size being much larger and most particles being substantially oblong or potato-shaped. This example demonstrates that the unique microstructure achieved by the MM process can produce LFP / graphite free-particulate materials that contain mostly large (10 μm average size), potato-shaped free particles, but have electrochemical properties that are superior in many respects to conventional LFPs, which consist mostly of submicron particles.

[0187] [Table 5]

[0188] [Example (IE3)] 25g Li[Ni 0.6 Mn 0.2 Co 0.2 ]O2 (the formula is designated as NMC622) particulate material (ShanShan T61 (#854)) was ground in an automatic grinder (RMO mortar grinder, Restch) for 30 minutes, resulting in the formation of submicron particulate material NMC, as shown in the SEM image in Figure 25. This raw particulate material was mixed with 225 g of ZrO2 spheres (50 μm, Glen Mills), which served as template particles, and the mixture was mechanofused at 1510 rpm for 30 minutes. After 30 minutes of mechanofusion, a uniform and smooth coating of NMC622 was achieved on the ZrO2 spheres, as shown in Figure 26.

[0189] The coated ZrO2 spheres were then impact milled, and much of the NMC622 was removed during the impact milling process. The flake-free particles were then separated from the partially coated ZrO2 spheres using a 38 μm sieve. Figure 27 shows an SEM image of the recovered flake-free particulate material. The flake-free particles have a characteristic flake morphology, with flake widths of 10–15 μm and flake thicknesses of 1–2 μm. Figure 28 shows the XRD pattern of the recovered flake-free particulate material. The characteristic peaks of NMC622 are evident, but the peak widths are broader. This indicates a reduction in grain size and the formation of defects in the structure after MM processing.

[0190] To remove the formed defects, the flake-free particulate material was heated in a flow of O2 gas at 800°C for 8 hours to obtain the final NMC622 flake-free particulate material. Figure 29 shows an SEM image of the resulting IE3 flake-free particulate material. It retains the characteristic flake morphology of the flake-free particulate material shown in Figure 27. Furthermore, it is evident that some flake particles peeled off during the heating process, and the NMC622 grains were arranged in intergranular layers parallel to the basal plane of the flakes, with each intergranular layer being up to approximately 200 nm thick. The IE3 flake-free particulate material had a flake diameter of 10-15 μm, a flake thickness of 1-2 μm, and a thickness of 0.4261 μm. 2 The density of the IE3 flake free particulate material was measured to be 4.874 g / ml. Combined with the BET surface area, this gives a BET surface area of ​​2.07 m 2 This corresponds to a VSA of 1 / ml. Figure 30 shows the XRD pattern of the IE3 flake free particulate material. Compared to the XRD pattern shown in Figure 28, it was observed that the XRD peaks were much narrower. This indicates that the heating step after the MM treatment resulted in grain growth and the disappearance of crystalline defects that occurred after the mechanofusion treatment.

[0191] From the IE3 XRD pattern, the average grain size and strain of NMC622 were determined to be 161 nm and 0.24%, respectively. Rietveld refinement of this XRD pattern revealed that the NMC lattice constants were a = 2.87261 Å and c = 14.2179 Å, and that the NMC grains were preferentially oriented in the

[0110] direction with a preferential orientation parameter of 1.308. This indicates that the NMC622 grains constituting the IE3 free particles are in the form of needle-like crystals arranged in intergranular layers within the IE3 free particles, with the long axes of the NMC622 needle-like crystals preferentially aligned with the major planes of the IE2 free particles.

[0192] Since the measured density is slightly higher than the theoretical density determined from the NMC lattice constants, the internal porosity of the IE3 flake free particulate material was determined to be 0%.

[0193] Electrodes in which IE3 flake free particulate matter served as the electroactive material were formulated according to Table 2. 3.531 g / cm, corresponding to an electrode porosity of 15%. 3 Electrode coating densities of 1000 .0001 .0001 .0001 .0002 .0003 .0004 .0005 .0006 .0007 .0008 .0009 ...

[0194] Lithium half-cells using the IE3 electrode coating as the working electrode were fabricated and cycled according to P1. Figure 32 shows the voltage curve for one of these cells. The voltage curve is typical of NMC622. The cell had an ICE of 94.8%, a reversible capacity of 189.78 mAh / g, and an average discharge voltage of 3.79 V. Using the electrode coating densities listed in Table 3, a coating energy density of 2473 Wh / L was obtained. Figure 33 shows the capacity of the same cell shown in Figure 32 plotted as a function of cycle number. The cell had a capacity loss of 12.8% and an average CE of 99.5% by 65 cycles.

[0195] The above examples demonstrate that dry processing methods according to embodiments of the present invention can be used to easily and quickly produce free particulate materials useful for battery applications. Furthermore, the particulate materials and electrodes made therefrom may have unique properties that are particularly desirable for battery applications.

[0196] All of the above U.S. patents, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications referenced herein are hereby incorporated by reference in their entirety.

[0197] While particular elements, embodiments, and applications of the present invention have been shown and described, it should be understood that the present invention is not limited thereto, as modifications may be made by those skilled in the art, particularly in light of the foregoing teachings, without departing from the spirit and scope of the present disclosure. For example, it is expected that other particulate materials and electrodes similar to the LiFePO4 and electrodes previously made can be made to have similarly unique properties. Such modifications are to be considered within the scope of the claims appended hereto. [Explanation of symbols]

[0198] 1 MF System 2 Cylindrical chambers 3 Press Head 4 scraper 5 Chamber wall 6 particle mixture

Claims

1. 1. A method of making free particles, comprising: obtaining a quantity of raw material particles and a quantity of template particles; dry mechano-fusion the quantity of feedstock particles and the quantity of template particles to form coated template particles comprising a feedstock particle coating on the template particles; impact milling the coated template particles to cause the feedstock particle coating to detach from the template particles and form free particles; Separating the free particles from the template particles; A method comprising:

2. The method of claim 1 , wherein the template particles are spherical and have a diameter of less than 200 μm.

3. The template particles are ZrO ２ The method of claim 1, wherein

4. The method of claim 1 , wherein the feedstock particles comprise a transition metal oxide or a transition metal phosphate.

5. Preface raw material particlesがA ｘ T ｙ M ｚ O ２ Also はA ｘ T ｙ M ｚ PO ４ (Wherein, x≧0, y≧0.5, z≧0, A is one or more intercalable alkali metals; T is one or more first row transition metals; M is selected from the group consisting of Mg, Al, Ti, Zr, W, Zn, Mo, K, Na, Si, Nb, and Ta. The method of claim 1 , comprising:

6. The raw material particles are LiFePO ４ and graphite, and the free particles are LiFePO ４ and graphite.

7. The method of claim 1 , wherein the feed particles comprise NMC and the loose particles comprise NMC.

8. 2. The method of claim 1, wherein the amount of the raw material particles and the amount of the template particles obtained are such that the ratio of the real volume of the raw material particles to the surface area of ​​the template particles corresponds to a coating thickness of 0.1 μm to 50 μm.

9. The method of claim 1 , wherein the impact milling is centrifugal impact milling.

10. 10. The method of claim 1, wherein the mechanofusion time is in the range of 30 seconds to 5 hours.

11. 2. The method of claim 1, wherein the impact milling time is in the range of 5 seconds to 1 minute.

12. 10. The method of claim 1, further comprising heating the free particles separated from the template particles at a temperature greater than 200°C to produce an electroactive positive electrode material.

13. 10. A loose particulate material comprising loose particles made by the method of claim 1.

14. 10. An electrode for an electrochemical cell comprising a porous electroactive coating on a current collector, said electroactive coating comprising free particulate matter produced by the method of claim 1.

15. 1. A free particulate matter comprising free particles of an electroactive material comprising more than 80% by weight of a metal oxide or metal phosphate electroactive phase, having a density greater than 3 g / ml and an average particle size in the range of 1 μm to 30 μm; the metal oxide or metal phosphate electroactive phase consists essentially of crystalline grains of size between 20 nm and 300 nm; the metal oxide and metal phosphate grains in the free particles have a preferred orientation with respect to a major plane of the particle, the preferred orientation parameter being greater than 1.02 or less than 0.98; the free particles have an average internal porosity of less than 20%; The volumetric surface area of ​​the free particles is 30 m ２ / ml or less, A free particulate material, wherein the free particles have an average aspect ratio of greater than 1.

5.

16. 16. The loose particulate matter of claim 15, wherein the loose particles have an average aspect ratio of at least 5.

17. 16. The loose particulate matter of claim 15, wherein the loose particles have an average aspect ratio of 1.5 or greater and less than 5.

18. 16. The loose particulate matter of claim 15, further comprising a conductive additive.

19. 20. The loose particulate matter of claim 18, wherein the conductive additive comprises carbon.

20. 20. The loose particulate matter of claim 19, wherein the carbon is graphite.

21. 16. The loose particulate matter of claim 15, wherein the grains have a crystallographic strain of less than 1%.

22. 16. The loose particulate matter of claim 15, wherein the grains are smaller than 200 nm.

23. The free particles are more than 80% by weight of LiFePO ４ are flakes in which an average flake diameter in the range of 5 μm to 50 μm; an average flake thickness in the range of 0.1 μm to 10 μm; an average aspect ratio of at least 5; 8m ２ / g or less; and 16. The free particulate matter of claim 15, having:

24. the average flake diameter is in the range of 5 μm to 25 μm; 24. The loose particulate matter of claim 23, wherein the average flake thickness is in the range of 0.1 μm to 5 μm.

25. The LiFePO ４ 24. The free particulate matter of claim 23, wherein the free particulate matter consists of grains having an average size of less than 0.3 μm.

26. 24. The loose particulate matter of claim 23, wherein the loose particles have a curvature with a radius of curvature in the range of 10 μm to 100 μm.

27. The free particles are more than 80% by weight of LiFePO ４ and The LiFePO ４ consists essentially of grains, LiFePO ４ the grains have a preferred orientation in the [101] direction with respect to the major plane of the free grains, the preferred orientation parameter being less than 0.98; The free particles are LiFePO ４ 16. The loose particulate matter of claim 15, comprising intergranular carbon domains, said carbon domains being in the range of between 0.1% and 10% by weight.

28. 28. The loose particulate matter of claim 27, wherein the carbon domains have an average size of less than 100 nm.

29. the free particles are greater than 80% by weight NMC; the NMC consists essentially of grains; 16. The free particulate matter of claim 15, wherein the grains of the NMC have a preferred orientation in the [110] direction with respect to the major planes of the free grains, with a preferred orientation parameter greater than 1.

02.

30. 1. An electrode for an electrochemical cell comprising a porous electroactive coating on a current collector, the electroactive coating comprising greater than 80% by weight of free particulate matter and a binder, The loose particulate matter comprises the loose particles of claim 15; the electrode coating has an electrode porosity of less than 20%; The loading of the electrode coating on the current collector is 2 mAh / cm ２ Super, electrode.

31. 31. The electrode of claim 30, wherein the free particulate matter comprises carbon.

32. 31. The electrode of claim 30, wherein the electrode coating has an electrode porosity that is less than 15%.

33. The electrode coating on the current collector has a loading of 3 mAh / cm ２ 31. The electrode of claim 30, wherein the

34. 31. A lithium-ion rechargeable battery comprising the electrode of claim 30.

35. 1. An electrode for a lithium-ion electrochemical cell comprising a porous electroactive coating on a current collector, said electroactive coating comprising greater than 10 wt. % free particles, LiFePO with more than 80% by weight of free particles ４ are crystal grains of the free particles are flakes having an aspect ratio of at least 5, a flake diameter in the range of 5 μm to 50 μm, and a flake thickness in the range of 0.1 μm to 10 μm; The free particles are ４ and carbon regions present between the grains in a range of between 0.1 wt. % and 10 wt. % of the carbon. the free particles have an internal porosity of less than 20%; The electrode, wherein the carbon domains have an average size of less than 100 nm.

36. The LiFePO ４ 36. The electrode of claim 35, wherein the grains have a preferred orientation in the [101] direction relative to the major planes of the free grains with a preferred orientation parameter that is less than 0.98.

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