High-capacity manganese-based rock salt cathode with structural variation

Abstract

Materials include phase transition disordered rock salts having an ordered arrangement of partially disordered spinel cations to provide suitable constant current cycling behavior. The phase transition disordered rock salt has the chemical formula LixMnyTMzO2-uFu, where 0.9 < = x < = 1.3, 0 < = y < = 1, 0 < = z < = 0.5, and 0 < = u < = 0.5, and TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W, or a mixture thereof. Further, the phase transition disordered rock salt includes a first set of domains and a second set of domains interspersed between the first set of domains. The second set of domains is separated from the first set of domains by one or more anti-phase domain boundaries. Methods and systems are described in the present disclosure.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit and priority of U.S. Provisional Application No. 63 / 495,826, filed April 13, 2023, and U.S. Provisional Application No. 63 / 571,580, filed March 29, 2024, which are incorporated herein by reference in their entirety for all purposes.

[0003] Claims regarding ownership of inventions resulting from federally funded research and development

[0004] This invention was completed with government support under contract number DE-AC02-05CH11231 granted by the U.S. Department of Energy. The government holds certain rights to this invention. Background Technology

[0005] With the increasing energy demands driven by electric vehicles with extended ranges and personal electronic devices capable of long-term operation, there is a need to develop high-energy-density cathode materials from elements abundant on Earth to meet these demands. Mn-based materials have been proposed for lithium-ion batteries to replace conventional cathodes, such as LiFePO4, due to their abundant global reserves, relatively low cost, and stability. Furthermore, the relatively low toxicity of Mn minerals and the high charge density of Mn... 4+ The high stability of manganese-based materials can provide safety benefits, which improves safety when batteries are integrated at the battery pack level.

[0006] While high capacities can be achieved in typical Mn-rich layered and spinel-type oxides, local structural variations and deformations can lead to voltage decay, capacity decay, and increased impedance, resulting in poor electrochemical performance over cycling. For example, typical spinels may undergo detrimental two-phase lithiation reactions present around 3 V, which can hinder the high energy density and rate capacity of Mn-based materials.

[0007] The implementation scheme described herein uses a synthesis strategy that induces a structural transformation in Mn-based rock salt materials, allowing for suitable rate performance and discharge capacity. The implementation scheme includes these and other improvements. Summary of the Invention

[0008] According to embodiments of the disclosure, a phase transition disordered rock salt (DRX) material includes nanometer-sized partially disordered spinel domains that enable suitable cycling performance. The phase transition DRX material can also be referred to as a delta phase material. The partially disordered spinel domains can be separated by one or more antiphase boundaries. The relatively small length of the partially disordered spinel domains can change the two-phase reaction of a typical spinel structure into a solid solution, such that when implemented as a cathode material, the phase transition DRX material can provide high energy density and rate capacity. Preparing the phase transition DRX material can include chemically delithiating a Mn-based DRX material and applying a subsequent heat treatment. Manganese is a low-toxicity, earth-abundant transition metal with a highly stable charged Mn 4+ state, which helps to improve battery safety and stability and can be sustainability. The chemical delithiation can cause the Mn-based DRX material to transition into a phase transition DRX material. The heat treatment can ensure that the Mn-based DRX material uniformly transitions into the phase transition DRX material.

[0009] In embodiments, a method of preparing a delta phase material can include providing a material comprising Li x Mn y TM z O 2-u F 1.2 where 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5, and 0 < u < 0.5, and TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W, or a mixture thereof. The non-migratable transition metals, including Ti, can prevent the formation of complete and long-range order. In addition, the method further includes delithiating the material to cause a phase transition of the material, forming a delta phase material comprising partially disordered spinel cationic ordering. The method can further include heat treating the delithiated material such that the delithiated material continues the phase transition to form the delta phase material. The delta phase material includes a first set of domains and a second set of domains interspersed among the first set of domains, where the second set of domains is separated from the first set of domains by one or more antiphase boundaries.

[0010] In embodiments, a battery can include a cathode comprising a phase transition disordered rock salt comprising Li x Mn y TM z O 2-u F uwhere 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5 and 0 < u < 0.5, TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W or a mixture thereof. The cathode can additionally include a first set of domains and a second set of domains interspersed among the first set of domains. The second set of domains can be separated from the first set of domains by one or more anti-phase domain boundaries. The battery can also include an anode. The battery can additionally include an electrolyte between the cathode and the anode.

[0011] A better understanding of the nature and advantages of embodiments of the application can be gained with reference to the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A schematic showing the structural changes of an exemplary Mn-based disordered rock salt material according to embodiments of the application to form a delta phase material through the synthesis steps.

[0013] Figure 2 A synchrotron X-ray diffraction (XRD) pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li 1.2 Mn 0.65 Ti 0.15 O 1.9 F 0.1 A synchrotron X-ray diffraction (XRD) pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li

[0014] Figure 3 A synchrotron XRD pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li Figure 2 after chemical delithiation.

[0015] Figure 4 A synchrotron XRD pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li Figure 2 after chemical delithiation and heat treatment at 200 °C for 2 hours.

[0016] Figure 5 A temperature-time curve and intensity plot of an exemplary Mn-based rock salt material according to embodiments of the application after partial delithiation using chemical delithiation, heated to 240 °C in increments of 30 °C.

[0017] Figure 6 A synchrotron XRD pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li

[0018] Figure 7 A synchrotron XRD pattern of an exemplary Mn-based rock salt material according to embodiments of the application having the chemical composition Li Figure 6XRD pattern shown in the middle in a magnified view from 4.5° to 7.5°.

[0019] Figure 8 An exemplary Mn-based rocksalt (DRX) material having the chemical composition Li 1.2 Mn0. 65 Ti 0.15 O 1.9 F 0.1 A high-angle annular dark field (HAADF) image of an exemplary Mn-based rocksalt (DRX) material.

[0020] Figure 9 An exemplary Mn-based DRX material having the chemical composition Li 1.2 Mn0. 65 Ti 0.15 O 1.9 F 0.1 An average scanning electron nanodiffraction (SEND) pattern of an exemplary Mn-based DRX material.

[0021] Figure 10 An intensity associated with a SEND pattern of an exemplary Mn-based DRX material according to an embodiment of the application, superimposed with a calculated disordered rocksalt peak. Figure 9

[0022] Figure 11 A HAADF image of an exemplary delithiated Mn-based DRX material according to an embodiment of the application.

[0023] Figure 12 A SEND pattern of an exemplary delithiated Mn-based DRX material according to an embodiment of the application.

[0024] Figure 13 A spatial distribution of an exemplary delta phase material in a disordered rocksalt material according to an embodiment of the application.

[0025] Figure 14 A HAADF image of an exemplary Mn-based DRX material that has undergone delithiation and heat treatment according to an embodiment of the application.

[0026] Figure 15 A SEND pattern of an exemplary particle of a Mn-based DRX material that has undergone delithiation and heat treatment according to an embodiment of the application.

[0027] Figure 16 A spatial distribution of an exemplary delta phase material according to an embodiment of the application.

[0028] Figure 17 An average SEND pattern of an exemplary Mn-based DRX material that has undergone delithiation and heat treatment according to an embodiment of the application.​

[0029] Figure 18 shows an integrated spatial distribution of exemplary delta phase material in one or more SEND patterns collected from an exemplary Mn-based DRX material according to embodiments of the application. Figure 17

[0030] Figure 19 shows an atomic resolution HAADF-STEM image of a portion of Figure 18 corresponding to the Fourier transform of the frequency components shown in the inset and having a scale of 5 nm.

[0031] Figure 20 shows a cationic ordering of the Fourier transform of the frequency components shown in Figure 19

[0032] Figure 21 shows a first cycle voltage profile of an exemplary electrochemical cell comprising an exemplary Mn-based DRX material as cathode active material when cycled at 2 V to 4.8 V, 20 mAh / g according to embodiments of the application.

[0033] Figure 22 shows a first cycle voltage profile of an exemplary electrochemical cell comprising an exemplary Mn-based DRX material subjected to delithiation and heat treatment as cathode active material when cycled at 2 V to 4.6 V, 20 mAh / g according to embodiments of the application.

[0034] Figure 23 shows the specific capacity retention of an exemplary Mn-based DRX material and an exemplary Mn-based delithiated and heat treated DRX material when cycled in different voltage windows at 20 mA / g according to embodiments of the application.

[0035] Figure 24 shows the specific energy retention of an exemplary Mn-based DRX material and an exemplary Mn-based delithiated and heat treated DRX material when cycled in different voltage windows at 20 mA / g according to embodiments of the application, wherein the exemplary Mn-based DRX has a chemical composition of Li 1.2 Mn 0.65 Ti 0.15 O 1.9 F 0.1 and the exemplary delithiated and heat treated Mn-based DRX material has a chemical composition of Li 0.7 Mn0. 65 Ti 0.1 O 1.9 F 0.1 and the exemplary delithiated and heat treated Mn-based DRX material has a chemical composition of Li​​

[0036] Figure 25 Rate capability of example electrochemical cells comprising Mn-based DRX as a cathode active material when discharged on the first cycle is shown for embodiments according to the present application when measured at 50 mA / g, 100 mA / g, 200 mA / g, and 500 mA / g from 2 V to 4.8 V.

[0037] Figure 26 Rate capability of example electrochemical cells comprising delithiated and heat treated Mn-based DRX as a cathode active material when discharged on the first cycle is shown for embodiments according to the present application when measured at 50 mA / g, 100 mA / g, 200 mA / g, and 500 mA / g from 2 V to 4.8 V.

[0038] Figure 27 Voltage profiles and in-situ XRD patterns of example delithiated and heat treated Mn-based DRX materials using X-ray scans every 30 minutes at a current rate of 20 mA / g are shown for embodiments according to the present application.

[0039] Figure 28 Voltage profiles and in-situ XRD patterns using X-ray scans every 30 minutes at a current rate of 20 mA / g are shown for embodiments according to the present application.

[0040] Figure 29 A flowchart of a process for preparing a delta phase material using a Mn-based disordered rock salt material is shown for embodiments according to the present application.

[0041] Figure 30 A flowchart of a process for preparing a delta phase material using charge / discharge cycling is shown for embodiments according to the present application.

[0042] Figure 31 Example batteries comprising a delta phase material as a cathode active material are shown for embodiments according to the present application. DETAILED DESCRIPTION

[0043] Current Li-ion cathodes, such as lithium nickel manganese cobalt oxide, can rely on the stability of nickel (Ni) and cobalt (Co) in octahedral sites to achieve stable cycling performance. While other transition metals, such as Cr, Mn, Fe, and Cu can be more abundant on earth than Ni and Co, these other transition metals lack the inherent site stability of Ni and Co. Thus, these transition metals require further processing and engineering to incorporate as Li-ion energy storage materials. Because of the charged Mn 4+The high stability of the state, Mn-based disordered rock salt materials can be suitable substitutes. However, Mn-based disordered rock salt materials often undergo a two-phase reaction upon cycling, which creates inhomogeneity and stresses in the material, limiting the energy density and rate capacity of these disordered rock salt materials.

[0044] Embodiments described herein include a delta phase material prepared by delithiating and heat treating a Mn-based disordered rock salt material. The delta phase material can be a nanostructured material having nanometer-sized partially ordered spinel domains with a coherence length of 1 nm to 10 nm. The partially ordered spinel domains can be separated by one or more anti-phase domain boundaries. The delta phase material can be characterized by a peak intensity ratio of a first x-ray diffraction (XRD) peak intensity to a second XRD peak intensity of 0.15 to 1. The first XRD peak intensity and the second XRD peak intensity can correspond to a first peak angle of 2° and a second peak angle of 5°, respectively, relative to a measurement wavelength of 0.1818 Å. Additionally or alternatively, the delta phase material can be characterized by a continuous increase in specific capacity over a voltage range of 2.6 V to 3.2 V, which indicates a lack of a two-phase lithiation reaction that limits the cycling performance of typical disordered rock salt materials. Delithiating the Mn-based disordered rock salt material can cause the Mn-based disordered rock salt material to phase transition into the delta phase material. Chemical delithiation can be applied to partially delithiate the Mn-based disordered rock salt material. Heating the delithiated Mn-based disordered rock salt material can cause the delithiated Mn-based disordered rock salt material to undergo further phase transition to form the delta phase material. The inherent stability of this ordered arrangement produces highly stable cycling retention performance.

[0045] Embodiments described herein can correspond to a Mn-based cathode material prepared using a Mn-based disordered rock salt material to provide improved capacity and rate performance compared to conventional rock salt materials. The Mn-based cathode material, when incorporated therein, can provide beneficial performance for various electrochemical cells, such as batteries. Heating the partially delithiated Mn-based disordered rock salt material can cause the Mn-based disordered rock salt material to form one or more partially ordered spinel domains that are in contact with each other at anti-phase domain boundaries. The partially ordered spinel domains can form a nano-tessellation structure. The size of the partially ordered spinel domains can be 3 nm to 7 nm, avoiding the two-phase lithiation reaction that typically occurs around 3 V in regular spinels. Additionally, Mn is thermally stable compared to other transition metals, such as Ni, even at full charge. Thus, incorporating the delta phase material as a battery electrode is beneficial for minimizing the risk of battery-related hazards.

[0046] Batteries including the Mn-based cathode material and methods for preparing the Mn-based cathode material are described in greater detail in the present disclosure.

[0047] I. Structural Characterization of DRX and Delta Phase Materials

[0048] Li 1.2 Mn 0.65 Ti 0.15 O 1.9 F 0.1 (Referring to L12M65 in this paper) is a disordered rock salt (DRX) that was chosen as the starting material for the preparation of the δ-phase material described herein due to its chemical composition. For example, its high Mn content and low Ti content have been shown to lead to a transformation in performance during electrochemical cycling. In addition, a 20% Li excess can achieve suitable Li ion percolation for battery applications or other electrochemical applications.

[0049] Figure 1 The structural changes for each synthesis step used to transform L12M65 110 into δ-phase material 120 are shown. L12M65 110 is synthesized via a solid-state method. Figure 1 As shown, after chemical delithiation, L12M65 110 begins to form partially disordered spinel (e.g., δ-phase material 120). Applying heat treatment can complete the transformation of L12M65 110 into δ-phase material 120. δ-phase material 120 may include at least one first domain 122a separated from at least one second domain 122b by antiphase domain boundaries 130. Figure 2 The synchrotron X-ray diffraction (XRD) pattern shown indicates that the synthesized L12M65 contains DRX without any detectable impurities. Based on the rock salt structure ( Fm-3m Rietveld refinement yielded a lattice parameter of 4.133 Å. The particle morphology of the synthesized L12M65, measured by scanning electron microscopy (SEM), showed a primary particle size of 20 μm. Deposition to Li was achieved by applying a 0.1 M NO2BF4 solution at 45 °C for 2 days. 0.7 Mn 0.65 Ti 0.15 O 1.9 F 0.1 (Refered in this paper as L07M65-D). XRD was performed to analyze the obtained L07M65-D. Figure 3 The peaks show a shift to higher angles, consistent with delithiation. Rietveld refinement based on the rock salt structure (Fm-3m) of L07M65-D yielded a refined lattice parameter of 4.067 Å. The appearance of some δ phases was also observed through the increase in intensity of the (111) peak at 2.13°.

[0050] After heat treatment at 200℃ for 2 hours, L07M65-D forms L07M65-DH, which shows a further increase in the intensity of the (111) peak, such as Figure 4SEM was performed to determine an average particle size of 12 pm. The broadening of the (111), (311), and (333) peaks, which are consistent with spinel ordering, indicates a short coherence length of cationic ordering. The spinel structure Fd- 3m Rietveld refinement was modeled on the spinel structure l with selective peak broadening applied to Bragg peaks with odd wp indices, yielding a good fit of R = 9.59 % and a refined lattice parameter of 8.211 A.

[0051] Figure 5 In situ XRD data is shown as the sample was heated from 100 °C to 600 °C. As shown, changes can be induced in the partially delithiated L07M65-D by this heat treatment. For example, a phase sequence from DRX to delta phase to spinel structure can be observed. Figure 6 A selection of XRD patterns corresponding to L07M65-D is shown after heating from 100 °C to 600 °C at each temperature shown in Figure 6 for 20 minutes. The perovskite peaks are denoted with subscript R and the spinel peaks are denoted with subscript S At 100 °C, L07M65-D shows the primary (002) and (022) peaks resulting from the DRX structure. From 150 °C to 200 °C, a broad feature of diffraction peaks with odd l indices appears (e.g., the (111) peak at 2.13° and the (311) peak at 4.21°). In contrast, Figure 7 An enlarged view of the (002) and (022) perovskite peaks in l shows that these perovskite peaks do not broaden, indicating that the grain size covered by the anionic lattice extension remains unchanged. From 250 °C to 500 °C, the diffraction peaks with odd Figure 5 indices sharpen and increase in intensity, as shown in Figure 6 and Figure 7 In addition, as shown in l the (002) and (022) peaks of the delta phase at about 5.11° and about 7.23° split, indicating the formation of a new phase with new peaks at 5.04° and 7.14°. In fact, peak splitting can be observed for all diffraction peaks with even Figure 6 indices. At above 500 °C, all peaks become sharper and the peak intensity increases, as shown in

[0052] In some embodiments, the delta phase material can be characterized with respect to its XRD peaks, as shown in Figure 6 andFigure 7 As one example, the delta phase material can have a first XRD peak at a peak angle of 2 degrees with a height-to-width ratio of 0.01 to 0.2 (e.g., 0.01 to 0.1, 0.1 to 0.2, or any value therebetween). As another example, the delta phase material can have a second XRD peak at a different peak angle of 5 degrees with another height-to-width ratio of 0.001 to 0.03 (e.g., 0.001 to 0.01, 0.01 to 0.03, or any value therebetween). Although the first XRD peak and the second XRD peak are described herein with reference to particular peak angles, it should be understood that the particular peak angles can vary based on the wavelength of the measurement. In other words, the first peak angle and the second peak angle can vary depending on the wavelength used for the XRD measurement of the delta phase material. The relationship between the peak angle and the wavelength of the measurement is provided as Equation 1 below.

[0053] In some embodiments, the delta phase material can be defined with respect to a peak intensity ratio of two XRD peaks (e.g., selected from the XRD peaks shown in Figure 6 and Figure 7 The peak intensity ratio can be 0.15 to 1 (e.g., 0.15 to 0.55, 0.55 to 1, or any value therebetween). As a non-limiting example, the peak intensity ratio can correspond to a ratio of a first XRD peak intensity at a first peak angle of about 2 degrees to a second XRD peak intensity at a second peak angle of about 5 degrees. The peak angle (e.g., the first peak angle and / or the second peak angle) can relate to a measurement wavelength according to Equation 1 below: (1) where n is an integer, l is the wavelength of the measurement, d corresponds to the lattice spacing between atomic planes of the phase transition disordered rock salt, and Q is the peak angle.

[0054] II. Atomic-Scale Characterization of Delta Phase Materials

[0055] To gain a more detailed understanding of the structural evolution of the samples upon chemical delithiation and heating, four-dimensional scanning electron nanodiffraction (SEND) was performed on L12M65 (as- synthesized), L07M65-D (after delithiation), and L07M65-DH (after delithiation and heat treatment at 200 °C). Figure 8 A high-angle annular dark-field (HAADF) image of L12M65 is shown on which the SEND patterns were collected. The average of diffraction patterns from this particle is shown in Figure 9 The sharp diffraction spots indicate the high crystallinity of the as-synthesized DRX particles. The selected diffraction patterns from the SEND data set (all of which can be indexed to the rock salt structure) indicate the absence of any other phases. The average diffraction pattern shows arc-like diffraction spots, indicating small in-plane rotational variations in this predominantly single-crystalline particle.Figure 10 The intensity of the diffraction peaks of the entire particle was radially integrated and compared to Fm-3m the powder pattern of the space group. The crystal planes perpendicular to the electron beam will not show in the TEM diffraction data, which can explain the absence of some simulated peaks in the experimental radially integrated diffraction pattern. Additionally, the kinematic diffraction approximation of the simulated DRX peaks does not capture the dynamic electron scattering that occurs due to the sample thickness, resulting in an intensity mismatch between the simulated and experimentally observed diffraction patterns.

[0056] Figure 11 An HAADF image of L07M65-D is shown. Figure 12 An average SEND pattern of the chemically delithiated L07M65-D particle is shown. Figure 11 An average SEND pattern of the chemically delithiated L07M65-D particle is shown. By integrating the intensity of the diffraction reflections unique to the δ-phase material from each SEND pattern and normalizing the intensity with the full collection scattering range (0.175 A -1 to 1.2 A -1 ), the spatial extent of the δ-phase material can be plotted. The effect of thickness normalization was investigated by using a control sample made with a focused ion beam with a uniform thickness. Figure 13 The spatial distribution of the δ-phase material is shown. The δ-phase intensity is higher in the surface layer (50 nm) than in the bulk. The results indicate that the majority of the DRX to δ conversion starts from the surface during delithiation. However, there are regions of significant DRX to δ conversion even in the bulk region.

[0057] A similar procedure was performed to plot the δ-phase extent in the L07M65-DH sample, which was chemically delithiated and subsequently heated at 200 °C for 2 hours. Figure 14 A STEM-HAADF image of a particle with an average SEND diffraction pattern of Figure 15 is shown. Figure 16 The entire particle is shown to uniformly convert to the δ-phase after heating. The δ-phase signal has a much higher intensity Figure 16 after heating, indicating that the heat treatment helps with the complete formation of the δ-phase.

[0058] To investigate the cationic ordering in the δ-phase in detail, enhanced SEND was performed on a particle from the L07M65-DH sample with atomic resolution HAADF imaging. To investigate the Li distribution after chemical delithiation, electron energy loss spectroscopy (EELS) of L07M65-DH was also measured on the same particle. A uniform intensity of the Li k-edge signal was observed throughout the particle, confirming that there was no preferential delithiation during synthesis or subsequent delithiation and heating. Figure 17 An average SEND pattern from this particle is shown.Figure 18 The integral of the diffraction peaks normalized to the full collected scattering range (0.175 A -1 to 1.2 A -1 ) confirms the entire particle has transformed into the delta phase. Region 1810 corresponds to the diffraction peak from Figure 18 The atomically resolved images marked with rectangular regions were collected and are further detailed in Figure 19 The fast Fourier transform of the HAADF-STEM micrograph is shown as an inset in Figure 19 The inverse Fourier transform of the spinel-like peak marked with a first circle 1910 and a second circle 1920 in the inset of Figure 20 is shown in Figure 19 . Figure 20 The fringes of the filtered images in Figure 19 are color-coded based on the isolated frequency components used to obtain them, as marked in the inset of Figure 19 . The ubiquitous presence of antiphase boundaries can be observed, where one variant of the spinel ordering meets another. An exemplary antiphase boundary is shown in the dashed box 2010 in the upper right corner of Figure 20 . In some embodiments, the domain size of the delta phase material is estimated to be 3 nm to 7 nm by calculating the average number of lattice fringes between antiphase boundaries of the delta phase material. The domain size is in good agreement with the calculated coherence length obtained by applying the Scherrer equation to the (111) XRD peak in Figure 4 .

[0059] III. Electrochemical performance of the delta phase material

[0060] The electrochemical performance of L07M65-DH and L12M65 was evaluated using constant current cycling between 2 V and 4.8 V at 20 mAh / g. After fabrication into cathode films, both samples maintained a large average particle size of close to 5 pm. As shown in Figure 21 , L07M65-DH delivered 201 mAh / g in the first discharge, significantly higher than the 159 mAh / g of L12M65. Voltage profiles 2110a and 2110b correspond to L12M65, while voltage profiles 2120a and 2120b correspond to L07M65-DH. As shown in Figure 22 , this improvement in cycling behavior was maintained in a narrower voltage window of 2 V to 4.6 V. The voltage profiles of L12M65, corresponding to voltage profiles 2210a and 2210b, are characterized by a largely linear relationship for the particular capacity range tested. In contrast, the voltage profiles 2220a and 2220b of L07M65-DH show plateau-like regions at 4 V and 3 V, with the 3 V region being longer than the 4 V region.

[0061] Figure 23 and Figure 24 show the specific capacity retention and specific energy retention of L12M65 and L07M65-DH when cycled in different voltage windows at 20 mA / g. As shown in Figure 24 L07M65-DH exhibits a maximum specific energy of 645 Wh / kg between 2 V and 4.8 V, and a maximum specific energy of 532 Wh / kg between 2 V to 4.6 V, which is higher than the value delivered by L12M65 in the same voltage region. In particular, L12M65 exhibits a maximum specific energy of 555 Wh / kg between 2 V to 4.8 V, and a maximum specific energy of 506 Wh / kg between 2 V to 4.6 V. Hard X-ray spectroscopy and soft X-ray maps of resonant inelastic X-ray scattering (mRIXS) reveal that Mn and oxygen redox contribute to the high capacity of L07M65-DH.

[0062] Figure 25 and Figure 26 show the rate performance of L12M65 and L07M65-DH at first cycle discharge when measured between 2 V and 4.8 V at different current densities. The capacity increase from L12M65 to L07M65-DH is accompanied by an improvement in rate capacity. The performance of L12M65 and L07M65-DH is tested at current densities of 50 mA / g to 500 mA / g, such as 50 mA / g, 100 mA / g, 200 mA / g, and 500 mA / g. As shown in Figure 25 the pristine L12M65 delivers only 68 mAh / g at 500 mA / g (42.7% of this value at 20 mA / g), while L07M65-DH shows significantly improved rate performance, delivering 110 mAh / g at 500 mA / g (54.6% of this value at 20 mA / g), as shown in Figure 26 This high specific energy and rate capacity has previously only been obtained in nanosized DRX materials, not in the microsized particles of delta phase materials described herein.

[0063] Further tests were performed to understand the structural processes upon electrochemical cycling. Figure 27 show in situ diffraction data obtained during cycling of L07M65-DH between 1.5 V and 4.8 V at 20 mA / g. For comparison, cycling data of well-ordered LiMn204spinel under the same conditions are shown in Figure 28In the L07M65-DH system, the (222), (400), and (440) peaks shift continuously to lower angles upon Li insertion, consistent with the continuous increase in lattice parameters. When discharged below 2.7V, the (400) and (440) peaks split, indicating the formation of a tetragonal phase. However, the lattice parameters of both the cubic and tetragonal phases continuously change during discharge, suggesting that the L07M65-DH system remains a solid solution. Conversely, Figure 28 Data from LiMn2O4 showed that when discharged across the entire 3 V plateau region, the (311), (400), and (440) peaks remained at the same angle, while their intensity gradually decreased.

[0064] like Figure 27 As shown, the diffraction peaks of L07M65-DH continuously shift within the voltage range of 2.6 V to 3.2 V, indicating the absence of a two-phase reaction. The continuous shift behavior of L07M65-DH is consistent with... Figure 28 The diffraction peaks of the LiMn2O4 spinel shown exhibit drastically different behavior. Furthermore, as... Figure 27 As shown, L07M65-DH exhibits a continuous increase in specific capacity over a voltage range of 2.6 V to 3.2 V, further supporting the absence of a two-phase reaction that adversely affects the cycling performance of typical spinel materials. Specifically, L07M65-DH can exhibit approximately 50 mAh-g over the voltage range. -1 Approximately 130 mAh-g -1 The specific capacity. In stark contrast to the continuous increase in specific capacity of L07M65-DH, LiMn2O4 spinel exhibits at least one plateau, which results in Figure 28 The step trend shown.

[0065] A. Correlation between nanoscale structural effects and electrochemical performance

[0066] Manganese's material properties make it a suitable transition metal for large-scale lithium-ion battery production. DRX cathodes can be doped with Mn as an active redox pair, but typically have limited rate capacity unless nanoscale. This disclosure describes a unique nanostructured but large-particle-size Mn-based cathode material with high specific energy, capacity, and suitable rate capacity. Although the voltage profile of this δ-phase material is similar to that of well-ordered LiMn₂O₄ spinel, significant differences exist between the two materials. For example, unlike regular spinel, the δ-phase material exhibits no two-phase reaction near 3 V and lithiation into a solid solution within this voltage range. Furthermore, the capacity of the δ-phase material is greater in the 3 V region than in the 4 V region. The two-phase reaction in regular spinel near 3 V can lead to inhomogeneity, resulting in particle breakage and degradation of the cathode material. Although two-phase reactions can be removed by generating cation disorder through mechanochemical synthesis involving a milling process, milling is impractical for large-scale production. The δ-phase material also exhibits better capacity and rate capacity than untransformed DRX with similar particle size, similar to the δ-like transformation observed when high-Mn-content DRX materials are slowly transformed into new structures through electrochemical cycling.

[0067] As disclosed herein, the unique nanoscale microstructure in the δ-phase material has been identified as the cause of its unique electrochemical behavior. We also demonstrate that the δ-phase material can be formed in situ via a non-in-situ method of chemical delithiation and cryogenic thermal treatment, which significantly reduces the time required for the DRX to δ-phase transition from 3 weeks to 2 days with an average particle size of approximately 10 μm.

[0068] The XRD and SEND analyses described in this paper provide a detailed characterization of the transformation of the L12M65 sample into a δ-phase material. During delithiation and heating, L07M65-DH exhibits spinel-type ordered cation-arranged cell doubling peaks, which have the following characteristics: Figure 4 The peaks shown are (111) at 2.13° and (311) at 4.21°. Meanwhile, Figure 10 The SEND analysis shown indicates that the δ-phase evolution begins on the surface of the L07M65-DH particles after chemical delithiation of L12M65. Figure 13 ), and after mild heating, the δ phase evolution progresses to a uniform transformation throughout the L07M65-DH particles ( Figure 16 These SEND findings are consistent with the XRD data. L07M65-D, prepared after chemical delithiation of L12M65, shows a weak (111) XRD peak. Figure 3 This indicates that the material was not completely transformed into the δ-phase. However, during heat treatment, the characteristic XRD peaks of the δ-phase were significantly enhanced. Figure 4 (), but still retains its wide profile. Even after the complete transformation, it has an odd number ofl The width of the XRD peaks of the exponents still exist, which is consistent with the small domain size indicated by the STEM-HAADF data. This multi-modal characterization clearly indicates that the delta phase is different from the ordered spinel and is characterized by a cationic order arrangement with a short coherence length, which is critical to avoid the deleterious two-phase reaction by solid solution behavior in the 3 V region.

[0069] Figure 20 The atomic structure of the delta phase material shown in the STEM-HAADF images shown reveals partially disordered spinel domains with a coherence length of 3 nm to 7 nm, separated by antiphase domain boundaries. The presence of antiphase domain boundaries reflects the high symmetry of the parent DRX phase that allows the formation of eight different spinel variants, such as two translational variants and four rotational variants. Thus, the process that occurs during delithiation and heating or other synthesis steps, such as cycling, appears to be a process in which spinel order starts in a randomly selected domain variant in DRX and then grows until it encounters another variant separated by an antiphase domain boundary. This understanding highlights the unique relationship between the delta phase material and DRX. Only when spinel is formed from the DRX rock salt structure can it produce a large number of spinel variants that can be maintained at nanometer size by touching each other at antiphase domain boundaries. The size of these domains appears to be significantly consistent and stable at about 3 nm to 7 nm, indicating that their further growth is limited, which can be due to a lack of driving force or due to the presence of immobile Ti ions between octahedral sites that cannot be easily moved.

[0070] The nanoscale domain structure and small coherence length, such as 3 nm to 7 nm, of the partially disordered spinel-like domains results in the electrochemical performance of the delta phase material. These characteristics of the delta phase material effectively suppress the two-phase reaction, similar to what is observed in nanomaterials. Reducing the coherence length in a material can turn a first-order transformation into a second-order transformation or completely remove the first-order transformation. In the delta phase material, the small coherence length has a significant impact on the electrochemical performance, removing the 3 V plateau and turning the associated phase transition into a solid solution region, as shown. Figure 27 This key feature of the delta phase material eliminates any phase transition strain that is a potential degradation mechanism as a cathode material and enables Mn-based spinels to be cycled over their entire theoretical capacity.

[0071] B. Comparison with other materials

[0072] The δ-phase material can be a suitable intermediate between a fully disordered DRX compound and a well-ordered spinel. In DRX materials, the randomly distributed cations create a broad Li site energy distribution, which leads to a sloped voltage profile and reduced Li diffusivity, necessitating small particle sizes in the cathode. By transforming the DRX material into a more ordered, partially spinel-like structure with a small coherence length, the energy density is increased due to the increase in capacity released in the 4 V and 3 V regions. The formation of the δ-phase material also improves the rate capability, consistent with previous theoretical work showing that spinel-like configurations have a more extensive low-barrier 0-TM percolation network, which is beneficial for Li transport. In the δ-phase material, more capacity is released at higher voltages, which is advantageous for power output in practical batteries. The δ-phase material approaches these spinel-like properties in terms of voltage profile and rate capability, while maintaining a small enough coherence length to remain a solid solution and prevent the two-phase reaction that occurs in ordered spinels. See Figure 27 and Figure 28 and related descriptions.

[0073] Due to its unusual nanoscale features of the microstructure, the δ-phase L07M65-DH releases 201 mAh / g capacity and high rate capacity at an average particle size of 4.7 μm. See Figures 21 to 26 and related descriptions. In sharp contrast, typical DRX materials can only release high capacity and energy density at particle sizes less than 500 nm. For example, DRX Li 1.3 Mn 0.4 Nb 0.3 O2typically only releases 101 mAh / g discharge capacity. By forming a δ-phase material in which the particle size is decoupled from the spinel domain size, a maximum specific energy of 645 Wh / kg can be achieved in L07M65-DH, which is higher than commercial cathode materials such as LiMn2O4and LiFePO4, and approaches that of LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NMC111). The δ-phase material has a crystal density of about 4 g / cc, which is between LiFePO4and NMC cathode materials. The present disclosure described herein shows the benefits of engineering local order and microstructure on the nanoscale and shows the application of the abundant Mn-based cathode materials on Earth.

[0074] IV. Exemplary Materials

[0075] In some embodiments, the material can include a phase transition disordered rock salt comprising Li x Mn y TM z O 2-u Fu where 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5 and 0 < u < 0.5, where TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W or a mixture thereof. In some embodiments, TM can correspond to one or more redox-inert transition metals that are used as a structural stabilizer for the disordered rock salt. Non-limiting examples of redox-inert transition metals include Zr, Nb, Mo, Sn, W or a mixture thereof. The phase transition of the disordered rock salt can be driven by an amount of Mn in the disordered rock salt. In other words, the phase transition of the disordered rock salt can occur based on the amount of Mn in the disordered rock salt being above a predetermined threshold, regardless of the transition metal or mixture of transition metals selected for making the disordered rock salt.

[0076] In some embodiments, the δ-phase material includes a first plurality of domains and a second plurality of domains interspersed among the first plurality of domains. The second plurality of domains can be separated from the first plurality of domains by one or more antiphase domain boundaries. The antiphase domain boundaries can form when the first plurality of domains and the second plurality of domains contact to exhibit opposite compositional bonds or opposite orderings at the interface. In some embodiments, the first plurality of domains includes a partially disordered spinel cation ordering. The second plurality of domains can include a disordered arrangement of metal atoms (e.g., transition metal atoms) on a cation lattice. The first plurality of domains can be more ordered than the disordered arrangement associated with the second plurality of domains. In other words, the first plurality of domains can correspond to a δ-phase material that can exhibit a partially disordered spinel cation ordering after delithiation and heat treatment. The second plurality of domains can correspond to a Mn-based disordered rock salt material used to make the δ-phase material.

[0077] The rock salt can include Li 1.05 Mn 0.85 Ti 0.1 O2, Li 1.1 Mn 0.7 Ti 0.2 O2, Li 1.15 Mn 0.55 Ti 0.3 O2, Li 1.2 Mn 0.4 Ti 0.4 O2, Li 1.2 Mn 0.5 Ti 0.3 O 1.9 F 0.1 , Li 1.2 Mn 0.7 Ti 0.1 O 1.9 F 0.1 , Li 1.1 Mn 0.75 Ti 0.15 O1.95 F 0.05 , Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 , Li 1.15 Mn 0.7 Ti 0.15 O 1.85 F 0.15 or Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 .

[0078] In some embodiments, the partial ordering of the spinel cations can suppress the two-phase reaction of the delta phase material over a range of voltages, for example, 2.6 V to 3.2 V (e.g., 2.6 V to 2.7 V, 2.7 V to 2.8 V, 2.8 V to 2.9 V, 2.9 V to 3.0 V, 3.0 V to 3.1 V, 3.1 V to 3.2 V, or any value in between). In some embodiments, the delta phase material exhibits a continuous shift in diffraction peaks at the range of voltages. In some embodiments, the delta phase material exhibits a continuous increase in specific capacity over the range of voltages. As a non-limiting example, the delta phase material can exhibit a specific capacity of about 50 mAh-g -1 to about 130 mAh-g -1 over the range of voltages.

[0079] In some embodiments, the delta phase material can be characterized based on XRD characteristics. As a non-limiting example, the XRD peaks of the delta phase material can have a height-to-width ratio of 0.001 to 0.2. For example, the height-to-width ratio of a particular XRD peak at a peak angle of 2°, relative to a measurement wavelength of 0.1818 A, can be 0.01 to 0.2 (e.g., 0.01 to 0.02, 0.02 to 0.03, 0.03 to 0.04, 0.04 to 0.05, 0.05 to 0.06, 0.06 to 0.07, 0.07 to 0.08, 0.08 to 0.09, 0.09 to 0.10, 0.10 to 0.11, 0.11 to 0.12, 0.12 to 0.13, 0.13 to 0.14, 0.14 to 0.15, 0.15 to 0.16, 0.16 to 0.17, 0.17 to 0.18, 0.18 to 0.19, 0.19 to 0.20, or any value in between). As another example, the height-to-width ratio of another XRD peak at a peak angle of 5°, relative to the measurement wavelength, can be 0.001 to 0.03 (e.g., 0.001 to 0.002, 0.002 to 0.003, 0.003 to 0.004, 0.004 to 0.005, 0.005 to 0.006, 0.006 to 0.007, 0.007 to 0.008, 0.008 to 0.009, 0.009 to 0.01, 0.01 to 0.011, 0.011 to 0.012, 0.012 to 0.013, 0.013 to 0.014, 0.014 to 0.015, 0.015 to 0.016, 0.016 to 0.017, 0.017 to 0.018, 0.018 to 0.019, 0.019 to 0.02, 0.02 to 0.021, 0.021 to 0.022, 0.022 to 0.023, 0.023 to 0.024, 0.024 to 0.025, 0.025 to 0.026, 0.026 to 0.027, 0.027 to 0.028, 0.028 to 0.029, 0.029 to 0.03, any value in between). It should be understood that the peak angles described herein can vary depending on the measurement wavelength, which can vary depending on the individual equipment or test conditions used for performing XRD. Equation 1 described herein can be used to determine the corresponding peak angle for a measurement wavelength that is different from 0.1818 A.

[0080] In some embodiments, the delta phase material can be characterized based on a peak intensity ratio of a first XRD peak intensity to a second XRD peak intensity, the peak intensity ratio being 0.15 to 1 (e.g., 0.15 to 0.20, 0.20 to 0.25, 0.25 to 0.30, 0.30 to 0.35, 0.35 to 0.40, 0.40 to 0.45, 0.45 to 0.50, 0.50 to 0.55, 0.55 to 0.60, 0.60 to 0.65, 0.65 to 0.70, 0.70 to 0.75, 0.75 to 0.80, 0.80 to 0.85, 0.85 to 0.90, 0.90 to 0.95, 0.95 to 1, or any value in between). The first XRD peak intensity can be at a first peak angle of 2° with respect to a measurement wavelength. The second XRD peak intensity can be at a second peak angle of 5° with respect to the measurement wavelength. As described above, the first peak angle and the second peak angle described herein can vary depending on the measurement wavelength.

[0081] As described herein, the partially disordered spinel cation ordering of the delta phase material can suppress the two-phase lithiation reaction typically exhibited in spinel structures during constant current cycling. The two-phase reaction can typically occur in a voltage range of 2.6 V to 3.2 V. In some embodiments, the delta phase material can have a coherence length of 1.0 nm to 10.0 nm (e.g., 1.0 nm to 2.0 nm, 2.0 nm to 3.0 nm, 3.0 nm to 4.0 nm, 4.0 nm to 5.0 nm, 5.0 nm to 6.0 nm, 6.0 nm to 7.0 nm, 7.0 nm to 8.0 nm, 8.0 nm to 9.0 nm, 9.0 nm to 10.0 nm, or any value in between). The coherence length can correspond to the size of the first plurality of domains forming the delta phase material. The relatively short coherence length can change the two-phase lithiation reaction to a solid solution, enabling high energy density and rate capacity at large particle scales. The delta phase material can have the same or similar material and structural properties as any of the delta phase materials described herein including but not limited to those described in reference to Figure 1 、 Figures 4 to 6 、 Figures 13 to 24 and Figures 26 to 27 .

[0082] V. Example Methods

[0083] Figure 29 is a flowchart of an example process 2900 for preparing a delta phase material according to embodiments of the present application. In some implementations, one or more of the process blocks of Figure 29 may be performed to prepare a delta phase material that can be incorporated into an electrochemical cell, such as the cell 3100 described below with reference to Figure 31 . The delta phase material can be any of the delta phase materials described herein.

[0084] At block 2910, a material comprising lithium (Li), one or more transition metals, oxygen, and fluorine is prepared. In some embodiments, a material having a chemical composition of Li x Mn y TM z O 2-u F u is prepared, where x is 0.9 to 1.3, y is 0 to 1, z is 0 to 0.5, and u is 0 to 0.5, and where TM is aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), niobium (Nb), molybdenum (Mo), tin (Sn), tungsten (W), or mixtures thereof. In some embodiments, the material can be a Mn-based disordered rock salt (DRX) material. The Mn-based disordered rock salt material can include a transition metal oxide material having a crystalline rock salt structure and a disordered arrangement of transition metals on the cation lattice. In some embodiments, the material can be prepared using a solid state synthesis method. The solid state synthesis method can include milling a mixture of one or more precursors, granulating the mixture to form granules, and sintering the granules to form the material.

[0085] At block 2920, the material is delithiated to induce a phase transition of the material, forming a delta phase material including a partially disordered spinel cation ordering. In some embodiments, the delithiation step can be a chemical delithiation, in which a chemical oxidant solution is applied to the material for up to 1 week (e.g., 0 to 1 hour, 1 to 5 hours, 5 to 10 hours, 10 to 20 hours, 20 to 30 hours, 30 to 40 hours, 40 to 50 hours, 50 to 100 hours, 100 to 150 hours, 150 to 168 hours, 10 hours to 48 hours, 30 hours to 50 hours, or any value therebetween). The chemical oxidant solution can include NO2BF4, (NH4)2SO4, other suitable chemical compounds having oxidizing properties, or mixtures thereof. In some embodiments, the delithiation amount of delithiation of the material can be 0.1 Li / chemical formula unit (f.u.) to 1 Li / f.u. For example, the delithiation amount can be 0.1 Li / f.u. to 0.2 Li / f.u., 0.2 to 0.3 Li / f.u., 0.3 Li / f.u. to 0.4 Li / f.u., 0.4 Li / f.u. to 0.5 Li / f.u., 0.5 Li / f.u. to 0.6 Li / f.u., 0.6 Li / f.u. to 0.7 Li / f.u., 0.7 Li / f.u. to 0.8 Li / f.u., 0.8 Li / f.u. to 0.9 Li / f.u., 0.9 Li / f.u. to 1.0 Li / f.u., or any value therebetween.

[0086] At block 2930, the delithiated material is heat treated such that the delithiated material continues to undergo a phase transition to form a delta phase material. The heat treatment of the delithiated material can include heating the delithiated material at a temperature of 100 °C to 500 °C (e.g., 100 °C to 200 °C, 200 °C to 300 °C, 300 °C to 400 °C, 400 °C to 500 °C, or any value in between). The heat treatment can be performed for up to 5 hours (e.g., 10 minutes to 30 minutes, 30 minutes to 1 hour, 1 hour to 2 hours, 2 hours to 3 hours, 3 hours to 4 hours, 4 hours to 5 hours, or any value in between). For example, the delithiated material can be heated at 200 °C under vacuum for 2 hours. After the heat treatment step, the delithiated material can optionally be quenched to room temperature.

[0087] The process 2900 can also include a step of preparing a cathode using the delta phase material. The cathode can be prepared in an inert atmosphere (e.g., argon, nitrogen, etc.). In some embodiments, the delta phase material can be combined with a carbon-based material (e.g., carbon black, graphitic carbon, graphene, conductive carbon, etc.) to form a composite powder, which can be mixed with a polymer (e.g., polytetrafluoroethylene) to form a mixed composite. The mixed composite can be rolled into a thin film and cut to prepare a cathode that can be incorporated into an electrochemical cell. The cathode including the delta phase material as a cathode active material can be used in battery applications (e.g., liquid batteries, solid state batteries, button batteries, square batteries, soft pack batteries, cylindrical batteries, etc.).

[0088] The process 2900 or certain steps of the process 2900 can be repeated or performed more than once. The process 2900 can include additional implementations, such as any single implementation or any combination of implementations described herein and / or in combination with one or more other processes described elsewhere in the text.

[0089] Although Figure 29 Example blocks of the process 2900 are shown, but in some implementations, the process 2900 can include additional blocks, fewer blocks, different blocks, or a different arrangement of blocks than those shown in FIG. 29. Figure 29 Additionally or alternatively, two or more blocks of the process 2900 can be performed in parallel.

[0090] Figure 30 is a flowchart of an example process 3000 for preparing a delta phase material using charge / discharge cycling according to embodiments of the application. In some embodiments, the delta phase material can be prepared by cycling a disordered rock salt material as a cathode in a lithium ion battery. The delta phase material can be any of the delta phase materials described herein.

[0091] In block 3010, a material comprising lithium (Li), one or more transition metals, oxygen, and fluorine is provided in a disordered rock salt phase. In some embodiments, providing said material involves a solid-state synthesis method to prepare the material in powder form. In some embodiments, said material is provided as a cathode in a lithium-ion battery. Providing the material as a cathode may include mixing the powdered material with a carbon-based material (e.g., carbon black) using mechanochemical mixing (e.g., high-energy ball milling) to reduce the particle size of the resulting cathode material. In some embodiments, the average particle size of the ball-milled cathode material may be from 2 μm to 10 μm (e.g., 2 μm to 3 μm, 3 μm to 4 μm, 4 μm to 5 μm, 5 μm to 6 μm, 6 μm to 7 μm, 7 μm to 8 μm, 8 μm to 9 μm, 9 μm to 10 μm, or any value between these). In some embodiments, the average particle size of the cathode material may be nanoscale, for example, in the range of several hundred nanometers.

[0092] In block 3020, the lithium-ion battery undergoes charge / discharge cycles, which transforms the disordered rock salt phase of the material into a delta-phase material. In some embodiments, the delta-phase material comprises a first plurality of domains and a second plurality of domains dispersed therebetween. The second plurality of domains may be separated from the first plurality of domains by one or more antiphase domain boundaries. The first plurality of domains and the second plurality of domains may be at least partially formed by the lithium-ion battery (e.g., referred to below). Figure 31 The described battery 3100) undergoes charge / discharge (e.g., constant current) cycles. For example, the charge / discharge cycle is performed at approximately 15 mAHg. -1 Up to 25 mAHg -1 (including approximately 15 to 20 mgAHg) -1 and approximately 20 to 25 mAHg -1 The charging / discharging cycle is performed at approximately 2 volts to 4.8 volts. The charge / discharge cycle voltage range can have a lower voltage of 1.5V to 2.0V, 2.0V to 2.5V, or 2.5V to 3.0V. The charge / discharge cycle voltage range can have a higher voltage of 4.0V to 4.5V, 4.5V to 5.0V, or 5.0V to 5.5V. The charge / discharge cycle can be performed for 15 to 25 cycles, for example, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 cycles.

[0093] In embodiments where one or more transition metals include manganese, under high voltage, the Mn present in the material... 4+ and Li +The vacancies can facilitate local cationic ordering, leading to the formation of the first plurality of domains and the second plurality of domains. In some embodiments, the average Mn oxidation state can be close to 3+ prior to charging the lithium ion battery. After charging the lithium ion battery to 4.8 volts, the Mn content in the cathode can be oxidized to 4+. After a subsequent discharge (e.g., 1.5 V), the average Mn oxidation state can return to 3+. During the discharge, the Mn 4+ Reduction and Li intercalation can transform the disordered rock salt phase to a partially disordered rock salt phase with a β'-LiFe02-type arrangement. The first plurality of domains and the second plurality of domains can be randomly oriented, allowing for reversible structural changes and stable electrochemical cycling.

[0094] Process 3000, or certain steps of process 3000, can be repeated or performed more than once. Process 3000 can include additional implementations, such as any single implementation or any combination of implementations described herein and / or in conjunction with one or more other processes described elsewhere in the text.

[0095] Although Figure 30 Example blocks of process 3000 are shown, but in some implementations, process 3000 can include additional blocks, fewer blocks, different blocks, or a different arrangement of blocks than those shown in FIG. 3. Additionally or alternatively, two or more blocks of process 3000 can be performed in parallel. Figure 30

[0096] VI. Example Battery

[0097] Figure 31 A schematic of an example battery 3100 incorporating the delta phase material described herein is shown, according to embodiments of the application. The cathode active material of battery 3100 can be prepared by performing all or part of process 2900. Although battery 3100 is described herein as a lithium ion battery, it should be understood that other alkali metal systems, alkaline earth metal systems, or other metal systems can be used in place of lithium. In embodiments, battery 3100 can be formed using a multi-layer stack of anodes and cathodes, for example, as in soft pack batteries, button self-batteries, or some square batteries. For simplicity, Figure 31 A single cathode 3120 and a single anode 3150 are shown.

[0098] Battery 3100 includes a cathode current collector 3110, a cathode 3120, an electrolyte 3130, a separator membrane 3140, an anode 3150, and an anode current collector 3160. In some embodiments, a cathode current collector 3110, a cathode 3120, an electrolyte 3130, a separator membrane 3140, an anode 3150, and an anode current collector 3160 can also be included in battery 3100. Figure 31 ​additional components or fewer components than those described. The cathode current collector 3110 can be any suitable material (e.g., a metallic element or a metallic compound) that is electrically conductive. In non-limiting examples, the cathode current collector 3110 includes aluminum.

[0099] As described herein, the cathode 3120 can include a delta-phase material as a cathode active material. In addition to the delta-phase material, the cathode 3120 can include other components, such as a conductive additive or a binder. In some embodiments, the cathode can include a first plurality of domains and a second plurality of domains interspersed among the first plurality of domains, one or more domain boundaries separating the first plurality of domains from the second plurality of domains. In some embodiments, the first plurality of domains and the second plurality of domains can be formed using chemical delithiation and heating.

[0100] The electrolyte 3130 can be a liquid electrolyte or a solid-state electrolyte. As a liquid electrolyte, the electrolyte 3130 can include a solvent and one or more salts dissolved in the solvent. Non-limiting examples of solvents include one or more carbonate solvents, such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), or any combination of these. A non-limiting example of a salt in the electrolyte 3130 includes LiPF6. In some embodiments, the electrolyte 3130 can include an additive, such as for stabilizing the battery 3100 or for use as a safety protecting agent to prevent overcharging or to provide flame retardancy.

[0101] The separator film 3140 can include any suitable ionically conductive and electrically insulating material. In non-limiting examples, the separator film 3140 is a porous polymeric layer. In some cases, the separator film can be a single or multi-layer polymeric sheet. Additionally or alternatively, the separator film 3140 can include a glass material, a ceramic material, a composite material, a coated material, or the like. In some embodiments, the separator film 3140 can be absent, such as when the cathode 3120 and the anode 3150 are separated by some other means. As another example, if the electrolyte 3130 is a solid-state electrolyte, the separator film 3140 can be omitted.

[0102] The anode 3150 can include any suitable material to provide a lithium alloying anode or a lithium uptake anode. In some non-limiting examples, the anode 3150 includes lithium metal or a lithium metal alloy, graphite, or the like. The anode current collector 3160 can include any suitable electrically conductive material. In non-limiting examples, the anode current collector 3160 includes copper.

[0103] As will be apparent to those of ordinary skill in the art after reading this disclosure, each of the various embodiments described and illustrated herein has discrete components and features that can be readily separated from those of any one of the other several embodiments without departing from the scope or spirit of the disclosure.

[0104] The above description of example embodiments of the present disclosure has been presented for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms described. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical application to those of ordinary skill in the art. While the disclosure has been described in some detail with specific reference to certain embodiments thereof, it will be apparent to those of ordinary skill in the art that various changes and modifications in form and details can be made therein without departing from the spirit and scope thereof.

[0105] Accordingly, the preceding merely illustrates the principles of the application. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the application and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the application as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present application, therefore, is not intended to be limited to the examples shown and described herein. Rather, the scope and spirit of the present application is embodied by the appended claims.

[0106] The indefinite articles "a" and "an," as used herein in a specification or in the claims, are defined as one or more unless explicitly stated otherwise. The use of the term "or" in the context of "A or B" is intended to mean an inclusive "or," i.e., "A or B" or both. The use of the term "at least one" is synonymous with "one or more." The use of the term "at least substantially" is intended to mean "at least one," "one or more," or "substantially all." The use of the term "about" is intended to mean "approximately," "around," or "at or near." The use of the term "based on" is intended to mean "based, at least in part, on."

[0107] Claims can be drafted to exclude any optional element. Thus, in this context, this statement is intended to serve as antecedent basis for the use of such exclusive terminology as "solely," "only," and the like in connection with the statement of the limitation of any claim element, or the use of a negative limitation.

[0108] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in the disclosed range is encompassed within the embodiments of the present disclosure. The upper and lower limits of these smaller ranges can independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the embodiments of the present disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of the included limits are also included in the embodiments of the present disclosure.

[0109] The terms“about” or“approximately” and the like are synonymous and are used analogously to indicate that a value modified by the term has a range of understanding associated with it, wherein the range can be ±20%, ±15%, ±10%, ±5%, or ±1%. The term“substantially” and the like is used to indicate that a value is close to a target value, wherein close can mean, for example, that the value is within 80% of the target value, within 85% of the target value, within 90% of the target value, within 95% of the target value, or within 99% of the target value.

[0110] All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference in their entirety for all purposes, as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference for all purposes and incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the cited publication is associated. None is admitted to be prior art.

Claims

1. A material comprising: Phase transition disordered rocksalt comprising Li x Mn y TM z O 2-u F u wherein 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5 and 0 < u < 0.5, TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W or a mixture thereof, and comprising: a first plurality of domains; and a second plurality of domains interspersed among the first plurality of domains, the second plurality of domains separated from the first plurality of domains by one or more antiphase domain boundaries.

2. The material of claim 1, wherein an XRD peak of the phase transition disordered rock salt has a height-to-width ratio at a peak angle of 2° of 0.01 to 0.

2.

3. The material of claim 1, wherein an XRD peak of the phase transition disordered rock salt has a height-to-width ratio at a peak angle of 5° of 0.001 to 0.

03.

4. The material of claim 1, wherein a peak intensity ratio of a first XRD peak intensity to a second XRD peak intensity of the phase transition disordered rock salt is 0.15 to 1, wherein the first XRD peak intensity is at a first peak angle of 2° and the second XRD peak intensity is at a second peak angle of 5°.

5. The material of any one of claims 2 to 4, wherein the peak angle relates to a measurement wavelength according to the following formula: n l = 2d sin Q, wherein n is an integer, l is the measurement wavelength, d corresponds to a lattice spacing between atomic planes of the phase transition disordered rock salt, and Q is the peak angle.

6. The material of claim 1, wherein the first plurality of domains comprises a partially disordered spinel cation order arrangement.

7. The material of claim 6, wherein the second plurality of domains comprises a disordered arrangement of metal atoms on a cation lattice, and wherein the first plurality of domains is more ordered than the disordered arrangement associated with the second plurality of domains.

8. The material of claim 6, wherein the partially disordered spinel cation order arrangement of the phase transition disordered rock salt suppresses a two-phase reaction of the phase transition disordered rock salt over a voltage range.

9. The material of claim 8, wherein the material exhibits a continuous shift in diffraction peaks over the voltage range, wherein the voltage range is 2.6 V to 3.2 V.

10. The material of claim 8, wherein the material exhibits a continuous increase in specific capacity over the voltage range.

11. The material of claim 10, wherein the material exhibits a specific capacity of about 50 mAh-g -1 to about 130 mAh-g -1 in the voltage range of 2.6 V to about 3.2 V.

12. The material of claim 1, wherein the rock salt comprises Li 1.05 Mn 0.85 Ti 0.1 O2, Li 1.1 Mn 0.7 Ti 0.2 O2, Li 1.15 Mn 0.55 Ti 0.3 O2, Li 1.2 Mn 0.4 Ti 0.4 O2, Li 1.2 Mn 0.5 Ti 0.3 O 1.9 F 0.1 , Li 1.2 Mn 0.7 Ti 0.1 O 1.9 F 0.1 , Li 1.1 Mn 0.75 Ti 0.15 O 1.95 F 0.05 , Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 , Li 1.15 Mn 0.7 Ti 0.15 O 1.85 F 0.15 , or Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 .

13. A method of making a delta phase material, the method comprising: A material comprising Li x Mn y TM z O 2-u F u is provided, wherein 0.9≤x≤1.3, 0<y≤1, 0<z≤0.5 and 0≤u≤0.5, TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W or a mixture thereof; delithiating the material to cause the material to phase transition into the delta phase material comprising a partially disordered spinel cation order arrangement; and heat treating the delithiated material such that the delithiated material continues the phase transition to form the delta phase material comprising a first plurality of domains and a second plurality of domains interspersed among the first plurality of domains, wherein the second plurality of domains is separated from the first plurality of domains by one or more antiphase domain boundaries.

14. The method of claim 13, wherein the delta phase material has a coherence length of 1.0 nm to 10.0 nm.

15. The method of claim 13, wherein the delithiating step comprises chemical delithiation.

16. The method of claim 14, wherein the delithiating step comprises applying a chemical oxidant solution to the material for up to 1 week, wherein the chemical oxidant solution is selected from the group consisting of NO2BF4 and (NH4)2SO4.

17. The method of claim 13, wherein the delithiation step has a delithiation amount of 0.1 Li / chemical formula unit to 1 Li / chemical formula unit.

18. The method of claim 13, wherein the heat treatment step has a temperature of 100 °C to 500 °C.

19. The method of claim 13, wherein the heat treatment step is performed at the temperature for up to 5 hours.

20. A battery, comprising: a cathode comprising a phase transition disordered rock salt comprising Li x Mn y TM z O 2-u F u wherein 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5 and 0 < u < 0.5, TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W or mixtures thereof, and comprising: a first plurality of domains; and a second plurality of domains interspersed among the first plurality of domains, the second plurality of domains separated from the first plurality of domains by one or more antiphase domain boundaries; an anode; and an electrolyte between the cathode and the anode.

21. The battery of claim 20, wherein the first plurality of domains and the second plurality of domains of the cathode are at least partially formed by subjecting the battery to charge / discharge cycles.

22. The battery of claim 21, wherein the charge / discharge cycle is from about 2 V to 4.8 V, about 15 mAHg -1 to 25 mAHg -1 at a current of 0.1 mA.

23. The battery of claim 21, wherein the charge / discharge cycles consist of 15 to 25 charge / discharge cycles.

24. A cathode comprising a delta phase material produced by the method of any one of claims 13 to 19.

25. A method, comprising: A material comprising Li x Mn y TM z O 2-u F u where 0.9 < x < 1.3, 0 < y < 1, 0 < z < 0.5 and 0 < u < 0.5, TM is Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Sn, W and mixtures thereof, the material is in a disordered rock salt phase and the material is a cathode in a lithium ion battery. and subjecting the lithium ion battery to charge / discharge cycles, the cycles causing the disordered rock salt phase to transform into a delta phase material, the delta phase material comprising a first plurality of domains and a second plurality of domains interspersed among the first plurality of domains, wherein the second plurality of domains is separated from the first plurality of domains by one or more antiphase domain boundaries.

26. The method of claim 25, wherein the charge / discharge cycle is from about 2 V to 4.8 V, about 15 mAHg -1 to 25 mAHg -1 per liter.

27. The method of claim 25, wherein the charge / discharge cycles comprise 15 to 25 charge / discharge cycles.

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