Coated lto LRMO cathode and synthesis

Abstract

A method of forming a high energy density composite cathode material is disclosed. The method comprises: providing a lithium rich manganese layered oxide (LRMO); coating the LRMO with a TiO2 precursor; and ball milling the TiO2 coated LRMO with LiH to form a LixTiO2 coated LRMO composite, wherein x is less than or equal to 1 and greater than zero.

Description

[0001] This application is a divisional application of the invention patent application filed on October 12, 2018, with application number 201811188662.0 and entitled "LRMO cathode coated with LTO and its synthesis". Technical Field

[0002] This disclosure relates to a lithium-ion battery cathode material and a method for producing the lithium-ion cathode material. Background Technology

[0003] Lithium-ion batteries have become a key technology for rechargeable electrochemical energy storage. Due to the electrochemical potential and theoretical capacity offered by lithium-ion batteries, this technology shows promise in large-scale energy storage systems, such as those related to the electrification of powertrains in automotive applications, and in providing stationary energy storage solutions for the efficient use of renewable energy. The energy density of conventional lithium-ion batteries may not be sufficient to meet the demands of next-generation applications.

[0004] Coating the surface of cathode materials with electrochemically inert oxides has been considered an effective method to improve the electrochemical performance of lithium-ion batteries; however, in some cases, cycle stability has not been improved. Lithium-rich manganese layered oxides or LRMO exhibit high specific capacity (i.e., >280 mAh g⁻¹). -1 LRMO cathode materials have the potential to meet the high energy demands of mobile electronic devices and electric vehicles, but they exhibit poor cycling performance, suboptimal rate performance, and voltage decay. Summary of the Invention

[0005] According to one embodiment, a method for forming a high energy density composite cathode material is disclosed. The method includes: providing a lithium-rich manganese layered oxide (LRMO); coating the LRMO with a TiO2 precursor; and ball milling the TiO2-coated LRMO with LiH to form a Li-coated composite cathode. x TiO2 LRMO composites, where x is less than or equal to 1 and greater than zero.

[0006] According to one or more embodiments, coating LRMO with a TiO2 precursor may include reacting LRMO with a titanium salt, deionized water, and an alcohol. The reaction may be performed in a hydrothermal reactor. The reaction may be carried out at a temperature of about 100°C to about 300°C for about 1 to about 12 hours. In one or more embodiments, the coating may include calcination to form TiO2 coating LRMO after the LRMO reaction. The calcination may be performed at about 300°C to about 500°C for about 30 minutes to about 8 hours. The calcination may be performed at a heating rate of about 1°C / min to about 10°C / min. In one or more embodiments, the TiO2 may be about 0.1 wt% to about 9 wt% of the TiO2-coated LRMO. In some embodiments, the LRMO may be xLi2MnO3•(1-x)LiMO2, where M may be Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals, or combinations thereof, and x may be less than or equal to 1 and greater than zero. In one or more embodiments, ball milling can be performed for about 6 hours to about 24 hours at a rate of about 200 rpm to about 750 rpm. In some embodiments, co-precipitated LRMO may be provided.

[0007] According to one embodiment, a method for forming a high energy density composite cathode material is disclosed. The method includes reacting a lithium-rich manganese layered oxide (LRMO) with a TiO2 precursor in a hydrothermal reactor; calcining the LRMO precursor; and ball milling the LRMO precursor with LiH to form a coated Li. x TiO2 LRMO composites, where x is less than or equal to 1 and greater than zero.

[0008] According to one or more embodiments, LRMO can be xLi2MnO3•(1-x)LiMO2, wherein M can be Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals or combinations thereof, and x can be less than or equal to 1 and greater than zero. In some embodiments, the TiO2 precursor can be from about 0.1 wt% to about 9 wt% of the LRMO of the coating precursor. In one or more embodiments, calcination can be performed at a heating rate of about 1 °C / min to about 10 °C / min. In some embodiments, ball milling can be performed at a rate of about 200 rpm to about 750 rpm for about 6 hours to about 24 hours. In one or more embodiments, the ratio of LiH to TiO2 used for ball milling can be from about 1:1 to about 1.10:1.

[0009] According to one embodiment, a high energy density cathode composite material is disclosed. The high energy density cathode composite material comprises a lithium-rich manganese layered oxide (LRMO) having the formula xLi₂MnO₃•(1-x)LiMO₂, where M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals, or combinations thereof, and x is less than or equal to 1 and greater than or equal to zero. The high energy density cathode composite material also includes ball-milled Li₂ on the surface of the LRMO. x TiO2 coating.

[0010] According to one or more embodiments, Li x The TiO2 coating can be a ball-milled LiH and TiO2 precursor composite coating on LRMO. In some embodiments, the LRMO can have the formula Li[Li (1-x-y-z) Ni x Co y Mn z O2, and x, y and z can each be independently less than or equal to 1 and greater than zero, or not exist. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the synthesis of coated LRMO according to one embodiment.

[0012] Figure 2A This is a graph showing the X-ray diffraction pattern of coated LRMO versus original LRMO according to one embodiment.

[0013] Figure 2B SEM images of the original LRMO ((a)-(c)) and the coated LRMO ((d)-(f)) according to one embodiment are shown.

[0014] Figure 3 This is a graph showing the initial charge and discharge curves of a coated LRMO according to one embodiment.

[0015] Figure 4 This is a graph showing the cyclic voltammetry curves of coated LRMO according to one embodiment.

[0016] Figure 5 This is a graph showing the cycling performance of the original LRMO and the coated LRMO according to one embodiment at 0.1C.

[0017] Figure 6 The graphs showing the charge and discharge curves of the original LRMO and the coated LRMO according to one embodiment are shown.

[0018] Figure 7This is a graph showing the rate performance of a pristine LRMO and a coated LRMO according to one embodiment. Detailed Implementation

[0019] Detailed embodiments of the invention are disclosed herein as requested; however, it should be understood that the disclosed embodiments are merely illustrative of the invention, which may be embodied in different and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the invention in different ways.

[0020] Unless otherwise expressly stated, all numerical quantities indicating dimensions or material properties in this specification should be understood to be modified by the word “about” in the course of describing the broadest scope of this disclosure. Practice within the stated numerical limits is generally preferred.

[0021] The initial definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation herein, and may be adapted to normal grammatical variations of the originally defined abbreviation. Unless expressly stated to the contrary, the measurement of a property is determined by the same technique as previously or subsequently mentioned for the same property.

[0022] Detailed reference is made to the compositions, embodiments, and methods of the present invention known to the inventors. However, it should be understood that the disclosed embodiments are merely illustrative of the invention, which may be embodied in different and alternative forms. Therefore, the specific details disclosed herein should not be construed as limiting, but rather serve as a representative basis for teaching those skilled in the art to employ the invention in various ways.

[0023] A description of a group or class of materials suitable for a given purpose in conjunction with one or more embodiments of the invention implies that a mixture of any two or more members of that group or class is appropriate. Descriptions of components in chemical terms refer to the components when added to any combination specified in the description and do not necessarily exclude chemical interactions between the components of the mixture after mixing. The initial definitions of acronyms or other abbreviations apply to all subsequent use of the same abbreviation herein, and appropriate modifications may be applied to normal grammatical variations of the originally defined abbreviations. Unless expressly stated to the contrary, measurements of properties are determined by the same techniques mentioned previously or subsequently for the same property.

[0024] A lithium-ion battery generates electricity by means of a cathode, an anode, and an electrolyte that connects and separates the two electrodes. Lithium ions migrate from one electrode to the other via the electrolyte, while the associated electrons are collected by the current collector and can be used as an energy source for an electrical device. A surface coating on the cathode material can improve the electrochemical performance of the lithium-ion battery.

[0025] In one or more embodiments of the present invention, a high-energy density cathode composite material and a method of forming the high-energy density cathode composite material are provided. A Li x TiO2 coating on the surface of a lithium-rich manganese layered oxide (hereinafter referred to as LRMO) serves as a cathode material for a lithium-ion battery (Li x TiO2@LRMO) provides high energy density and improved cycling stability. The Li x TiO2 coating is uniformly and effectively formed on the surface of LRMO by ball-milling LRMO coated with a TiO2 precursor with lithium hydride (LiH). The TiO2 precursor is coated on the surface of LRMO in a hydrothermal reactor. Thus, a Li x TiO2@LRMO composite material is formed, and the composite material provides a high-energy density cathode with improved cycling stability, rate performance, and voltage decay. The method is a cost-effective, convenient, efficient, and scalable method for industrial production and provides a high-performance new-generation cathode material for lithium-ion batteries.

[0026] Reference Figure 1 , schematically shows the synthesis of a Li x TiO2@LRMO composite cathode material. First, the LRMO material is synthesized. The LRMO material can be prepared by any conventional method such as, but not limited to, co-precipitation. According to one or more embodiments, LRMO is represented by the following formula: xLi2MnO3·(1-x)LiMO2 (M = Mn, Ni, Co, 0 < x < 1). Although the lithium-rich manganese layered oxide is presented as an example, the method of the present invention is not intended to be limiting. Thus, the Li x TiO2 coating synthesis method and its promising influence can also be used for other cathode materials such as lithium metal phosphates (LiMPO4) or LRMO oxides (where M = Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals, etc.) or a certain combination thereof, and the following examples are intended to be non-limiting examples.

[0027] The synthesized LRMO material is reacted to form an intermediate composite material of LRMO coated with a TiO2 precursor coating. The reaction occurs in a hydrothermal reactor. To prepare the intermediate composite material (or precursor / TiO2-coated LRMO), LRMO, a titanium salt, deionized water, and an alcohol are combined and placed in the hydrothermal reactor. In the hydrothermal reaction, the alcohol can be, but is not limited to: ethylene glycol, ethanol, propanol, propylene glycol, glycerol, or combinations thereof. In the hydrothermal reaction, the titanium salt can be, but is not limited to: titanium trichloride, titanium tetrachloride, tetrabutyl titanate, titanium tetrafluoride, or combinations thereof. The combined reactants can be mixed in certain molar ratios before being provided to the reactor. For example, to form a mixed solution for the hydrothermal reaction, the LRMO material and the titanium salt are added to a water / alcohol solution under stirring. The mixed solution is then provided to the hydrothermal reactor containing the LRMO material. The water to alcohol ratio in the hydrothermal reactor can be from about 1:10 to about 1:60. Preferably, the ratio of water to alcohol in the hydrothermal reactor is about 1:10, 1:20, 1:30, 1:40, 1:50, or 1:60. The hydrothermal reaction can be carried out at a temperature of about 100°C to about 300°C, or more preferably 120°C to 180°C, for about 1 to about 12 hours.

[0028] Following the hydrothermal reactor, the intermediate composite material is collected, dried, and calcined to form TiO2@LRMO (precursor / TiO2-coated LRMO). Calcination can be performed in a laboratory furnace, a high-temperature oven, or any other equipment capable of calcination. The calcination treatment can be performed at a calcination temperature of about 300°C to about 500°C. The heating rate to reach the calcination temperature can be about 1°C / min to about 10°C / min. The calcination treatment can be performed for about 30 minutes to about 8 hours. After calcination, an LRMO of the coating precursor with a TiO2 content of about 0.1 wt% to 9 wt% of LRMO is obtained. Preferably, the TiO2 content can be from 1 wt% to 5 wt% of LRMO.

[0029] After calcination, TiO2@LRMO is ball-milled with lithium hydride (LiH) to form a LixTiO2@LRMO composite cathode material. The ratio of LiH to TiO2 used for ball milling can be from about 1:1 to about 1.10:1. Ball milling can be performed at a rate of about 200 to about 750 rpm. The ball milling process can be performed for about 6 hours to about 24 hours. The Li on the LRMO material after ball milling... x The amount of TiO2 coating can be from about 0.1% to 9% by weight. Preferably, the LiO2 coating on the ball-milled LRMO material... x The amount of TiO2 coating can be about 1% by weight and about 5% by weight. In some embodiments, Li on the LRMO material xThe amount of TiO2 coating can be approximately 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, or 9 wt%.

[0030] Li x The TiO2@LRMO active material can then be incorporated into the cathode of a lithium-ion battery. An exemplary cathode may include approximately 80% by weight Li. x TiO2@LRMO, approximately 10 wt% conductive agent and 10 wt% binder. The conductive agent can be any suitable conductive agent, including but not limited to Super P carbon black. The binder can be any suitable binder, including but not limited to polyvinylidene fluoride.

[0031] Therefore, a high-energy-density cathode composite material and a method for forming said high-energy-density cathode composite material are provided. Li on the surface of LRMO x TiO2 coating (Li x TiO2@LRMO, as a cathode material, provides high energy density and improved cycle stability, rate performance, and voltage decay for lithium-ion batteries. Hydrothermal reaction and ball milling offer cost-effective, convenient, efficient, and scalable methods for industrial production, and provide high-performance next-generation lithium-ion battery cathode materials.

[0032] Experimental results Example 1 Sample 1 First, 1.4553 g of LRMO material was added to a mixed solution consisting of 0.7030 g TiCl3 / HCl solution (16 wt%), 0.7 ml water, and 25 ml ethylene glycol over 30 minutes with ultrasonic stirring. The solution was then transferred to a 60 ml hydrothermal reactor, where the hydrothermal reaction was performed at 150 °C for 4 hours. The resulting sample was filtered, washed, dried, and then calcined in air at 350 °C for 4 hours. The target product, Li, was obtained after ball milling with a certain amount of LiH at 500 rpm for 12 hours. x TiO2@LRMO. In sample 1, Li x The TiO2 concentration was estimated to be 5% by weight.

[0033] Figure 2A A comparison of the X-ray diffraction patterns of the original LRMO and LixTiO2@LRMO (sample 1) is shown. Figure 2A This demonstrates that the coating process does not alter the structure of lithium-rich manganese layered oxide materials. Figure 2B The original LRMO and Li were shown. x SEM image of TiO2@LRMO (sample 1) material. Lix The surface of TiO2@LRMO is well coated with a certain amount of lithium titanate, and Li x TiO2@LRMO is nearly spherical with a particle size of several hundred nanometers.

[0034] Using Li x The detailed steps for assembling lithium-ion batteries using TiO2@LRMO as the cathode material are briefly described below: The working electrode consists of 80% by weight Li x The active material is TiO2@LRMO, and the active material consists of 10 wt% conductive agent (Super P carbon black) and 10 wt% binder (polyvinylidene fluoride). All electrodes are punched into aluminum foil (diameter: 12 mm). The lithium foil is used as the counter electrode in the half-coin cell. LiPF6 (1 mol / L) in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of EC:DEC = 1:1 is used as the electrolyte, and a polypropylene membrane (Celgard 2300) is used as the separator.

[0035] Figure 3 Li was shown x Initial charge / discharge curves of TiO2@LRMO (sample 1) at a current density of 30 mA / g in the range of 2.0 to 4.8 V. The initial discharge capacity was 272 mAh / g.

[0036] Figure 4 Li was shown x CV curve of TiO2@LRMO (sample 1) at a scan rate of 0.1 mV / s. Figure 5 Li was shown x Cyclic performance of TiO2@LRMO (sample 1) at a current density of 0.03 A / g. Figure 6 The charge / discharge curves and average discharge voltage of Sample 1 and the original LRMO are shown. Figure 7 The rate performance of Sample 1 and LRMO is shown.

[0037] Samples 2-5 Similar to Example 1, lithium-rich layered oxide materials (LRMOs) with varying amounts of lithium titanate were obtained by adjusting the amount of lithium titanate. Other synthesis conditions and battery fabrication were similar to those in Example 1. The test results for battery performance are shown in Table 1.

[0038] Table 1

[0039] Sample 6-13 Other samples were synthesized according to Example 1 by varying the ball milling time and rate while keeping all other conditions constant. The test results for battery performance are shown in Table 2.

[0040] Table 2

[0041] Samples 14-17 Based on Example 1, other samples were synthesized by varying the time and temperature of the hydrothermal reaction while keeping other conditions the same as in Example 1. The test results for battery performance are shown in Table 3.

[0042] Table 3

[0043] Samples 18-21 Samples 18-21 were prepared by changing the calcination reaction time and temperature of Example 1 while keeping other conditions the same as in Example 1. The test results of battery performance are shown in Table 4.

[0044] Table 4

[0045] While exemplary embodiments have been described above, it is not intended to describe all possible forms of the invention for these embodiments. Rather, the terminology used herein is descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the invention. Furthermore, features of various embodiments may be combined to form other embodiments of the invention.

[0046] According to the present invention, a method for forming a high energy density composite cathode material is provided: providing a lithium-rich manganese layered oxide (LRMO); coating the LRMO with a TiO2 precursor; and ball milling the TiO2-coated LRMO with LiH to form a Li-coated composite cathode material. x TiO2 LRMO composites, where x is less than or equal to 1 and greater than zero.

[0047] According to one embodiment, coating LRMO with a TiO2 precursor involves reacting LRMO with a titanium salt, deionized water, and an alcohol.

[0048] According to one embodiment, the reaction is carried out in a hydrothermal reactor.

[0049] According to one embodiment, the reaction is carried out at a temperature of about 100°C to about 300°C for about 1 hour to about 12 hours.

[0050] According to one embodiment, coating includes calcination after LRMO reaction to form LRMO coated with TiO2.

[0051] According to one embodiment, calcination is performed at about 300°C to about 500°C for about 30 minutes to about 8 hours.

[0052] According to one embodiment, calcination is performed at a heating rate of about 1°C / min to about 10°C / min.

[0053] According to one embodiment, TiO2 is about 0.1% to about 9% by weight of the TiO2-coated LRMO.

[0054] According to one embodiment, LRMO is xLi2MnO3•(1-x)LiMO2, where M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals or combinations thereof, and x is less than or equal to 1 and greater than zero.

[0055] According to one embodiment, ball milling is performed for about 6 hours to about 24 hours at a rate of about 200 rpm to about 750 rpm.

[0056] According to one embodiment, a co-precipitated LRMO is provided.

[0057] According to the present invention, a method for forming a high energy density composite cathode material is provided: reacting lithium-rich manganese layered oxide (LRMO) with a TiO2 precursor in a hydrothermal reactor; calcining the LRMO precursor; and ball milling the LRMO precursor with LiH to form a coated Li x TiO2 LRMO composites, where x is less than or equal to 1 and greater than zero.

[0058] According to one embodiment, LRMO is xLi2MnO3•(1-x)LiMO2, where M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals or combinations thereof, and x is less than or equal to 1 and greater than zero.

[0059] According to one embodiment, the TiO2 precursor is about 0.1% to about 9% by weight of the coating precursor LRMO.

[0060] According to one embodiment, calcination is performed at a heating rate of about 1°C / min to about 10°C / min.

[0061] According to one embodiment, ball milling is performed for about 6 hours to about 24 hours at a rate of about 200 rpm to about 750 rpm.

[0062] According to one embodiment, the ratio of LiH to TiO2 used for ball milling is about 1:1 to about 1.10:1.

[0063] According to the present invention, a high energy density cathode composite material is provided, comprising: a lithium-rich manganese layered oxide (LRMO) having the formula xLi₂MnO₃•(1-x)LiMO₂; and ball-milled Li₂ on the surface of the LRMO. x TiO2 coating, wherein M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals or combinations thereof, and x is less than or equal to 1 and greater than or equal to zero.

[0064] According to one embodiment, Li x The TiO2 coating is a composite coating of ball-milled LiH and TiO2 precursors on LRMO.

[0065] According to one embodiment, LRMO has the formula Li[Li (1-x-y-z) Ni x Co y Mn z ]O2, and x, y and z are each independently less than or equal to 1 and greater than zero, or do not exist.

Claims

1. A method for forming a composite cathode material, the method comprising: Provides lithium-rich manganese layered oxides; The manganese layered oxide was coated with a TiO2 precursor. as well as The TiO2-coated manganese layered oxide was ball-milled using LiH to form a Li-coated layer. x TiO2 manganese layered oxide composite material, wherein x is less than or equal to 1 and greater than zero.

2. The method of claim 1, wherein coating the manganese layered oxide with the TiO2 precursor comprises reacting the manganese layered oxide with a titanium salt, deionized water and an alcohol.

3. The method of claim 2, wherein the reaction is performed in a hydrothermal reactor.

4. The method of claim 2, wherein the reaction is carried out at a temperature of 100°C to 300°C for 1 hour to 12 hours.

5. The method of claim 2, wherein the coating comprises calcining the manganese layered oxide after reacting the manganese layered oxide to form the coated TiO2 manganese layered oxide.

6. The method of claim 5, wherein the calcination is performed at 300°C to 500°C for 30 minutes to 8 hours.

7. The method of claim 6, wherein the calcination is performed at a heating rate of 1°C / min to 10°C / min.

8. The method of claim 1, wherein the TiO2 is 0.1% to 9% by weight of the manganese layered oxide coated with TiO2.

9. The method of claim 1, wherein the manganese layered oxide is xLi2MnO3•(1-x)LiMO2, wherein M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, rare earth metals or combinations thereof, and x is less than or equal to 1 and greater than or equal to zero.

10. The method of claim 1, wherein the ball milling is performed at a rate of 200 rpm to 750 rpm for 6 to 24 hours.

11. The method of claim 1, wherein the provision includes co-precipitation of the manganese layered oxide.

12. A cathode composite material, the cathode composite material comprising: A lithium-rich manganese layered oxide having the formula xLi₂MnO₃•(1-x)LiMO₂, wherein M is Mn, Ni, Co, Fe, Cr, Ti, Al, Mg, V, a rare earth metal or a combination thereof, and x is less than or equal to 1 and greater than or equal to zero; and The ball-milled Li on the surface of the manganese layered oxide x TiO2 coating, The Li x The TiO2 coating is formed by ball milling the manganese layered oxide coated with the TiO2 precursor using LiH.

13. The cathode composite material of claim 12, wherein the ratio of LiH to TiO2 used for ball milling is from 1:1 to 1.10:

1.

14. The cathode composite material of claim 12, wherein the manganese layered oxide has the formula Li[Li (1-x-y-z) Ni x Co y Mn z ]O2, and x, y and z are each independently less than or equal to 1 and greater than zero, or do not exist.

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