O3 phase layered oxide material and preparation method and application thereof

Abstract

The application provides an O3 phase layered oxide material and a preparation method and application thereof. The preparation method comprises the following steps: providing a mixed slurry containing a sodium source, a nickel source, an iron source, a manganese source, a tin source, an M source and a first metal oxide, performing centrifugal spray drying on the mixed slurry to obtain a precursor powder; mixing the precursor powder with a second metal oxide, and performing solid-phase sintering in an oxygen-containing atmosphere to obtain the O3 phase layered oxide material; the first metal oxide comprises copper oxide and / or magnesium oxide; the second metal oxide contains a high-valence strong-bonding cation, the valence of the high-valence strong-bonding cation is greater than or equal to +4, and the bond energy of the bond formed by the high-valence strong-bonding cation and oxygen anions is greater than or equal to 600 kJ / mol; the M source provides one or more combinations of zinc, aluminum, titanium and antimony. The O3 phase layered oxide material can improve the discharge platform, rate performance and long cycle stability of a sodium ion battery based on the synergistic effect of oxide doping with a high-valence strong-bonding cation and high-entropy effect.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to an O3 phase layered oxide material, its preparation method, and its application. Background Technology

[0002] To reduce the excessive consumption of fossil fuels and meet the demands of sustainable energy development, the development of low-cost, highly safe electrochemical energy storage technologies has become an urgent need. Lithium-ion batteries, with their advantages of high energy density and long cycle life, have already taken a dominant position in consumer electronics, electric vehicles, and energy storage. However, the scarcity and uneven geographical distribution of lithium resources limit the long-term sustainable development of lithium-ion batteries. Against this backdrop, sodium-ion batteries, due to the abundance, wide distribution, and low cost of sodium resources, and their similar electrochemical working principle to lithium-ion batteries, are widely considered to have the potential to form a stable complementary relationship with lithium-ion batteries. However, the core challenge for the commercial application of sodium-ion batteries lies in how to develop cathode materials that combine high energy density, long cycle life, excellent rate performance, and low cost.

[0003] Among the many cathode materials for sodium-ion batteries, O3-type layered oxide cathode materials have advantages such as high theoretical capacity, strong structural tunability, and relatively mature synthesis process, showing broad application prospects. However, the development of this type of cathode material faces the following inherent problems: (1) During charging / discharging, significant slippage of the transition metal layer will be accompanied by multiple irreversible complex phase transitions, resulting in rapid capacity decay during long cycles; (2) The capacity of common O3-type layered cathode materials is mainly concentrated in the low voltage region of about 3.0 V, which limits the development of high energy density; (3) In the O3-type layered cathode crystal structure, sodium ions can only diffuse within the sodium layer plane, and the diffusion path is octahedron-tetrahedron-octahedron. This process requires overcoming a high energy barrier, which greatly limits the diffusion dynamics of sodium ions, thus exhibiting poor rate performance.

[0004] To address this, researchers have applied the concept of high entropy to the preparation of high-entropy layered oxide cathode materials, aiming to overcome the bottlenecks in cycle life and rate performance of sodium-ion battery cathode materials. However, existing high-entropy designs are typically simple multi-element combinations that neglect the interactions between elements. Overly random element distributions can raise the migration barrier of sodium ions, which, while improving structural stability, limits rate performance. Furthermore, for high-entropy components, traditional solid-state methods are prone to elemental segregation and impurity phase formation, making it difficult to obtain cathode materials with highly uniform single-phase structures. Summary of the Invention

[0005] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions:

[0006] A first aspect of the present invention provides an O3 phase layered oxide material, wherein the chemical formula of the O3 phase layered oxide material is: Na(Ni a Fe b Mn c Sn d M e A f ) 1-g B g O2, a=0.2~0.4, b=0.1~0.2, c=0.2~0.4, d=0.05~0.15, e=0.05~0.1, f=0.05~0.15, g=0.005~0.02, a+b+c+d+e+f+g=1; wherein, A is selected from copper and / or magnesium, B is selected from one or more of zirconium, tantalum, tungsten, molybdenum, and niobium, and M is selected from one or more of zinc, aluminum, titanium, and antimony;

[0007] The O3 phase layered oxide material includes secondary particles formed by the stacking of primary particles. The ratio of the longest diagonal to the shortest diagonal of the orthographic projection profile of the primary particles is defined as R, where 1≤R≤1.4, and the average grain size of the primary particles is less than 2.2μm. The secondary particles are spherical particles with pores on the surface and inside.

[0008] In some embodiments, the average grain size of the primary particles is 1.8 μm to 2.2 μm.

[0009] In some embodiments, the average diameter of the secondary particles is 30 μm to 40 μm.

[0010] In some embodiments, the porosity of the secondary particles is 10% to 25%.

[0011] A second aspect of the present invention provides a method for preparing an O3 phase layered oxide material, comprising:

[0012] A uniform mixed slurry containing sodium source, nickel source, iron source, manganese source, tin source, M source and first metal oxide is provided, and centrifugally spray-dried to obtain precursor powder.

[0013] The precursor powder was mixed with a second metal oxide and solid-state sintered in an oxygen-containing atmosphere to obtain an O3 phase layered oxide material.

[0014] The first metal oxide includes copper oxide and / or magnesium oxide; the second metal oxide contains a high-valence strongly bonded cation, wherein the valence of the high-valence strongly bonded cation is greater than or equal to tetravalence and the bond energy of the bond formed with the oxygen anion is greater than 600 kJ / mol; the M source provides a metal element M, wherein the metal element M includes one or more of zinc, aluminum, titanium and antimony.

[0015] On the one hand, Ni, Fe, Mn, Sn, M, Cu, and / or Mg, as high-entropy elements, generate a high-entropy effect. The chemical disorder induced by the design of high-entropy components can reduce the Gibbs free energy of the system and improve the thermodynamic stability of the material. The inherent lattice distortion of high-entropy components produces a retarded diffusion effect, increasing the difficulty of transition metal ion migration and effectively delaying the structural decay of the layered structure into spinel or rock salt phase during cycling. The copper and / or magnesium provided by the first metal oxide can increase the configurational entropy of the cathode material, giving the material stronger structural stability; tin can reduce the orbital hybridization of the transition metal layer, increase the ionicity of the nickel-oxygen bond, and increase the redox potential of nickel, thereby improving the discharge plateau and energy density of the battery, solving the problems of low discharge plateau (about 3.0 V) and poor structural stability of O3-type layered oxide cathode materials.

[0016] On the other hand, the introduction of a second metal oxide during solid-state sintering allows its high-valence, strongly bonded cations to form strong bonds with oxygen anions, which helps to mitigate the slippage of the transition metal layer during the phase transition. The strong metal-oxygen bonding suppresses lattice oxygen precipitation in the highly desodium-degraded state, thus solving the problem of oxygen framework instability. Through the synergistic effect of the doping effect and high entropy effect of the second metal oxide containing high-valence, strongly bonded cations, sodium-ion batteries based on this O3-phase layered oxide material exhibit a high discharge plateau, excellent rate performance, and superior long-cycle stability.

[0017] In some embodiments, the first metal oxide preferably includes copper oxide.

[0018] In some embodiments, the second metal oxide includes one or a combination of more of zirconium dioxide, tantalum oxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide.

[0019] Copper oxide and / or magnesium oxide, along with other metal oxides, also act as sintering aids during solid-state sintering. During solid-state sintering, copper oxide and / or magnesium oxide initially form a low-melting-point eutectic with the main phase material at temperatures below their melting points, thus optimizing grain boundaries. As the solid-state sintering temperature increases, oxides containing highly valence-state strongly bonded cations segregate towards the grain boundaries, exerting a pinning effect and effectively inhibiting grain boundary migration, preventing excessive grain coarsening that might be induced by copper oxide and / or magnesium oxide. It should be noted that copper oxide and / or magnesium oxide, along with oxides containing highly valence-state strongly bonded cations, need to be introduced stepwise. Copper oxide and / or magnesium oxide are added during the raw material preparation step and participate in the spray drying process, ensuring uniform mixing with the main material components. This facilitates their preferential entry into the material interior during subsequent sintering to form a low-melting-point eutectic. The addition of oxides containing highly valence-state strongly bonded cations during the solid-state sintering step helps them distribute at the grain boundaries of the precursor powder, thereby preventing excessive grain boundary growth during sintering and inhibiting grain coarsening.

[0020] The O3-phase layered oxide material obtained in this way exhibits highly uniform elemental distribution, a high-entropy single-phase structure, and a morphology consisting of near-spherical secondary particles formed by the accumulation of fine, highly rounded primary particles. This solves the problems of poor elemental distribution uniformity and irregular morphology in high-entropy oxide systems. The highly rounded primary particles effectively eliminate stress concentration points to suppress particle cracking, exhibiting a relatively smaller specific surface area, which stabilizes the particle surface energy, helps reduce interfacial side reactions, and improves the material's interfacial stability. Simultaneously, the more compact and thorough packing of the primary particles not only constructs a three-dimensional fast ion transport network but also reduces the porosity within the secondary particles, preventing excessive electrolyte consumption.

[0021] In some embodiments, the M source includes one or a combination of zinc oxide, aluminum oxide, titanium dioxide, and antimony pentoxide.

[0022] In some embodiments, the tin source includes one or a combination of stannous oxide, tin dioxide, and tin acetate, preferably tin dioxide.

[0023] In some embodiments, the sodium source includes one or a combination of sodium carbonate, sodium hydroxide, sodium acetate, and sodium nitrate. Preferably, the sodium source includes sodium carbonate and / or sodium hydroxide.

[0024] In some embodiments, the nickel source includes one or a combination of nickel carbonate, nickel hydroxide, nickel acetate, nickel nitrate, and nickel oxide; preferably, the nickel source includes nickel oxide.

[0025] In some embodiments, the iron source includes one or more of ferric acetate, ferric nitrate, ferrous oxide, ferric oxide, and magnetite, preferably ferric oxide.

[0026] In some embodiments, the manganese source includes one or a combination of manganese carbonate, manganese acetate, manganese nitrate, manganese dioxide, manganese trioxide, and manganese tetroxide. Preferably, the manganese source includes manganese dioxide.

[0027] In some embodiments, the inlet temperature of the centrifugal spray dryer is 130℃~200℃, the outlet temperature is 80℃~130℃, and the centrifugal speed is 10000~18000 rpm.

[0028] In some embodiments, the solid-state sintering temperature is 850℃~1000℃.

[0029] In some embodiments, the holding time for solid-state sintering is 10 h to 20 h.

[0030] In some embodiments, the heating rate of the solid-state sintering is 1℃ / min to 5℃ / min.

[0031] In some embodiments, a sodium source, a nickel source, an iron source, a manganese source, a tin source, an M source, a first metal oxide, and a solvent are mixed and then wet-milled to form a uniform slurry. The wet-milling speed is 200 rpm to 800 rpm, and the milling time is 6 h to 20 h.

[0032] In some embodiments, the solid content of the mixed slurry is 20% to 40%.

[0033] In some embodiments, the amounts of sodium source, nickel source, iron source, manganese source, tin source, M source, first metal oxide, and second metal oxide satisfy the chemical formula Na(Ni) a Fe b Mn c Sn d M e A f ) 1-g B g O2, where A represents copper and / or magnesium provided by the first metal oxide, B represents a high-valence, strongly bonded cation provided by the second metal oxide, a=0.2~0.4, b=0.1~0.2, c=0.2~0.4, d=0.05~0.15, e=0.05~0.1, f=0.05~0.15, g=0.005~0.02, a+b+c+d+e+f+g=1.

[0034] A third aspect of the present invention provides an O3 phase layered oxide material, which is prepared by the preparation method described in any of the technical solutions.

[0035] The O3-phase layered oxide material described in the first aspect of this invention can be prepared using the preparation method provided in the second aspect of the invention. Based on the grain boundary regulation during sintering by copper oxide and / or magnesium oxide, as well as oxides containing strongly bonded cations in high valence states, the obtained O3-phase layered oxide material exhibits a spherical secondary particle morphology with appropriate porosity, formed by the accumulation of fine primary particles with high roundness. The roundness of the primary particles can be characterized by R, which is the ratio of the longest diagonal to the shortest diagonal of the orthographic projection profile of the primary particle. When R is closer to 1, the projection profile is closer to a circle, resulting in higher roundness. Furthermore, high-valence elements such as Zr, Nb, and Ta can effectively suppress grain coarsening caused by the presence of copper oxide, thereby obtaining primary particles with smaller grain sizes (1.8 μm~2.2 μm).

[0036] A fourth aspect of the present invention provides a positive electrode for a sodium-ion battery, the positive electrode comprising a positive electrode active material, the positive electrode active material comprising the O3 phase layered oxide material described in any of the technical solutions.

[0037] The fifth aspect of the present invention provides a sodium-ion battery, wherein the positive electrode of the sodium-ion battery is the positive electrode for a sodium-ion battery according to any of the technical solutions.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] (1) The preparation method provided by the present invention introduces a first metal oxide and a second metal oxide in steps. The first metal oxide is added in the raw material preparation step and participates in the spray drying process, so that it is uniformly mixed with the main components of the material. This is beneficial for it to preferentially enter the interior of the material during the subsequent sintering process to form a low-melting-point eutectic, thereby optimizing the grain boundaries. The second metal oxide is added in the solid-state sintering step, which is beneficial for its distribution at the grain boundaries of the precursor powder, thereby preventing excessive grain boundary growth during the sintering process and inhibiting grain coarsening. The O3 phase layered oxide material obtained in this way has highly uniform element distribution, high-entropy single-phase structure characteristics, and its morphology is a spherical secondary particle formed by the accumulation of fine primary particles with high roundness.

[0040] (2) The high-valence, strongly bonded cations in the second metal oxide introduced in this invention can form strong bonds with oxygen anions, enabling the prepared material to alleviate the slippage of the transition metal layer during the phase transition process. Strong metal-oxygen bonding suppresses lattice oxygen evolution in the highly desodium-free state, thus solving the problem of oxygen framework instability. Simultaneously, the O3-phase layered oxide material provided by this invention also employs a high-entropy configuration design. Through the synergistic effect of the doping effect of the second metal oxide and the high-entropy effect, sodium-ion batteries based on this O3-phase layered oxide material exhibit a high discharge plateau, excellent rate performance, and superior long-cycle stability. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is the XRD pattern of the cathode material prepared in Example 1;

[0043] Figure 2 These are SEM and EDS images of the cathode material prepared in Example 1;

[0044] Figure 3 This is the XRD pattern of the cathode material prepared in Comparative Example 1;

[0045] Figure 4 These are the SEM and EDS images of the cathode material prepared in Comparative Example 1.

[0046] Figure 5 These are the SEM and EDS images of the cathode material prepared in Comparative Example 7.

[0047] Figure 6 The rate performance diagram is based on the battery sample from Example 1.

[0048] Figure 7 This is a graph showing the long-cycle performance of the battery sample based on Example 1;

[0049] Figure 8 The discharge curves of the battery samples based on the cathode materials of Comparative Example 1 and Comparative Example 2 are shown.

[0050] Figure 9 The diagram shows the long-cycle performance of the cathode materials based on Comparative Examples 1, 3, and 4.

[0051] Figure 10 This is a SEM image of the cathode material prepared in Comparative Example 10. Detailed Implementation

[0052] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0053] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0054] Example 1

[0055] This embodiment provides an O3 phase layered oxide material and its preparation method, specifically including the following steps:

[0056] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, titanium dioxide and copper oxide were weighed according to the metal molar ratio Na: Ni: Fe: Mn: Sn: Ti: Cu = 1.05: 0.3: 0.2: 0.2: 0.1: 0.1: 0.1. They were dispersed in deionized water and ball-milled. The solid content was set to 30%, the ball milling speed was 600 rpm and the ball milling time was 15 h to obtain a uniform mixed slurry.

[0057] (2) The uniform slurry obtained after ball milling is pumped into a spray dryer for spray drying. The inlet temperature is set to 150 ℃, the outlet temperature is set to 100 ℃, and the centrifugation speed is set to 15000 rpm to obtain precursor powder.

[0058] (3) The precursor powder and zirconium dioxide were mixed at a metal molar ratio of (Ni+Fe+Mn+Sn+Ti+Cu):Zr = 0.99:0.01 to obtain a mixture. The mixture was heated to 950 °C at a heating rate of 5 °C / min and calcined for 15 h in an air atmosphere. After cooling, it was immediately transferred to an argon atmosphere glove box for storage to obtain zirconium-doped sodium-ion battery O3-type high-entropy layered cathode material with the chemical formula Na(Ni 0.3 Fe 0.2 Mn 0.2 Sn 0.1 Ti 0.1 Cu 0.1 ) 0.99 Zr 0.01 O2.

[0059] Examples 2-5

[0060] Examples 2-5 are basically the same as Example 1, except that the oxide type containing a high-valence strongly bonded cation is used in step (3) as shown in Table 1. The rest are the same as in Example 1, and will not be repeated here.

[0061] Table 1. Oxides containing strongly bonded cations in high valence states used in Examples 1-5

[0062] Example 6

[0063] Example 6 is basically the same as Example 1, except that in step (1) of Example 6, magnesium oxide is used instead of copper oxide. The rest is the same as in Example 1, and will not be repeated here.

[0064] Example 7

[0065] This embodiment provides an O3 phase layered oxide material and its preparation method, specifically including the following steps:

[0066] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, antimony pentoxide and copper oxide were weighed according to the metal molar ratio Na: Ni: Fe: Mn: Sn: Sb: Cu = 1.02: 0.25: 0.2: 0.2: 0.1: 0.15, dispersed in deionized water and ball-milled. The solid content was set to 20%, the ball milling speed was set to 800 rpm, and the ball milling time was set to 6 h to obtain a uniform mixed slurry.

[0067] (2) The ball-milled slurry was pumped into a spray dryer for spray drying. The inlet temperature was set to 130℃, the outlet temperature to 80℃, and the centrifugation speed to 18000 rpm to obtain precursor powder.

[0068] (3) The precursor powder and tantalum oxide were mixed at a metal molar ratio of (Ni+Fe+Mn+Sn+Sb+Cu):Ta = 0.98:0.02 to obtain a mixture. The mixture was heated to 850 °C at a heating rate of 3 °C / min and calcined for 20 h in an air atmosphere. After cooling, it was immediately transferred to an argon atmosphere glove box for storage to obtain a tantalum-modified sodium-ion battery high-entropy layered cathode material with the chemical formula Na(Ni 0.25 Fe 0.2 Mn 0.2 Sn 0.1 Sb 0.1 Cu 0.15 ) 0.98 Ta 0.02 O2.

[0069] Example 8

[0070] This embodiment provides an O3 phase layered oxide material and its preparation method, specifically including the following steps:

[0071] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, aluminum oxide and copper oxide were weighed according to the metal molar ratio Na: Ni: Fe: Mn: Sn: Al: Cu = 1.0: 0.3: 0.15: 0.3: 0.1: 0.1: 0.05. They were dispersed in deionized water and ball-milled. The solid content was set to 40%, the ball milling speed was set to 600 rpm, and the ball milling time was set to 12 h to obtain a uniform mixed slurry.

[0072] (2) The uniform slurry obtained after ball milling is pumped into a spray dryer for spray drying. The inlet temperature is set to 200 ℃, the outlet temperature is set to 130 ℃, and the centrifugation speed is set to 10000 rpm to obtain precursor powder.

[0073] (3) The precursor powder and niobium pentoxide were mixed at a metal molar ratio of (Ni+Fe+Mn+Sn+Al+Cu):Nb = 0.98:0.02 to obtain a mixture. The mixture was heated to 1000 °C at a heating rate of 1 °C / min and calcined for 12 h in an air atmosphere. After cooling, it was immediately transferred to an argon atmosphere glove box for storage to obtain niobium-modified sodium-ion battery high-entropy layered cathode material with the chemical formula Na(Ni 0.3 Fe 0.15 Mn 0.3 Sn 0.1 Al 0.1 Cu 0.05 ) 0.98 Nb 0.02 O2.

[0074] Example 9

[0075] This embodiment provides an O3 phase layered oxide material and its preparation method, specifically including the following steps:

[0076] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, zinc oxide and copper oxide were weighed according to the metal molar ratio Na: Ni: Fe: Mn: Sn: Zn: Cu = 1.02: 0.25: 0.2: 0.3: 0.1: 0.05: 0.1, dispersed in deionized water and ball-milled. The solid content was set to 30%, the ball milling speed was set to 200 rpm, and the ball milling time was set to 20 h to obtain a uniform mixed slurry.

[0077] (2) The uniform slurry obtained after ball milling is pumped into a spray dryer for spray drying. The inlet temperature is set to 180 ℃, the outlet temperature is set to 120 ℃, and the centrifugation speed is set to 13500 rpm to obtain precursor powder.

[0078] (3) The precursor powder and molybdenum trioxide were mixed at a metal molar ratio of (Ni+Fe+Mn+Sn+Zn+Cu):Mo = 0.995:0.005 to obtain a mixture. The mixture was heated to 950 °C at a heating rate of 2 °C / min and calcined for 10 h in an air atmosphere. After cooling, it was immediately transferred to an argon atmosphere glove box for storage to obtain a molybdenum-modified sodium-ion battery high-entropy layered cathode material with the chemical formula Na(Ni) 0.25 Fe 0.2 Mn 0.3 Sn 0.1 Zn 0.05 Cu 0.1 ) 0.995 Mo 0.005 O2.

[0079] Example 10

[0080] This embodiment provides an O3 phase layered oxide material and its preparation method, specifically including the following steps:

[0081] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, aluminum oxide and copper oxide were weighed according to the metal molar ratio Na: Ni: Fe: Mn: Sn: Al: Cu = 1.03: 0.3: 0.1: 0.3: 0.1: 0.1: 0.1. They were dispersed in deionized water and ball-milled. The solid content was set to 25%, the ball milling speed was set to 800 rpm, and the ball milling time was set to 8 h to obtain a uniform mixed slurry.

[0082] (2) The uniform slurry obtained after ball milling is pumped into a spray dryer for spray drying. The inlet temperature is set to 160 ℃, the outlet temperature is set to 110 ℃, and the centrifugation speed is set to 14000 rpm to obtain precursor powder.

[0083] (3) The precursor powder and tungsten trioxide were mixed at a metal molar ratio of (Ni+Fe+Mn+Sn+Al+Cu):W = 0.995:0.005 to obtain a mixture. The mixture was heated to 900 °C at a heating rate of 2 °C / min and calcined for 15 h in an air atmosphere. After cooling, it was immediately transferred to an argon atmosphere glove box for storage to obtain a tungsten-modified sodium-ion battery high-entropy layered cathode material with the chemical formula Na(Ni 0.3 Fe 0.1 Mn 0.3 Sn 0.1 Al 0.1 Cu 0.1 ) 0.995 W 0.005 O2.

[0084] Comparative Example 1

[0085] The only difference between Comparative Example 1 and Example 1 is that in step (1), sodium carbonate, nickel oxide, ferric oxide, and manganese dioxide were weighed according to the metal molar ratio Na:Ni:Fe:Mn = 1.05:0.4:0.2:0.4, and zirconium dioxide was not added in step (3). All other steps were carried out in the same manner as in Example 1 to obtain a sodium-ion battery cathode material with the chemical formula NaNi. 0.4 Fe 0.2 Mn 0.4 O2.

[0086] Comparative Example 2

[0087] The difference between Comparative Example 2 and Example 1 is only that in step (1), sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, and titanium dioxide are weighed according to the metal molar ratio Na:Ni:Fe:Mn:Sn:Ti = 1.05:0.4:0.2:0.2:0.1:0.1, and zirconium dioxide is not added in step (3). The other steps are the same as in Example 1, to obtain a sodium-ion battery cathode material with the chemical formula NaNi. 0.4 Fe 0.2 Mn 0.2 Sn 0.1 Ti 0.1 O2.

[0088] Comparative Example 3

[0089] The only difference between Comparative Example 3 and Example 1 is that in step (1), sodium carbonate, nickel oxide, ferric oxide, and manganese dioxide were weighed according to the metal molar ratio Na:Ni:Fe:Mn = 1.05:0.4:0.2:0.4. The other steps were the same as in Example 1, resulting in a sodium-ion battery cathode material with the chemical formula Na(NiO2). 0.4 Fe 0.2 Mn 0.4 ) 0.99 Zr 0.01 O2.

[0090] Comparative Example 4

[0091] The only difference between Comparative Example 4 and Example 1 is that zirconium dioxide is not added in step (3), while the rest is carried out in the same manner as in Example 1, to obtain a high-entropy cathode material for sodium-ion batteries with the chemical formula NaNi. 0.3 Fe 0.2 Mn 0.2 Sn 0.1 Ti 0.1 Cu 0.1 O2.

[0092] Comparative Example 5

[0093] The only difference between Comparative Example 5 and Example 1 is that zirconium dioxide is replaced with yttrium oxide in step (3), while the rest is carried out in the same manner as in Example 1, resulting in an equivalent yttrium-doped high-entropy cathode material for sodium-ion batteries with the chemical formula Na(Ni) 0.3 Fe 0.2 Mn 0.2 Sn 0.1 Ti 0.1 Cu 0.1 ) 0.99 Y 0.01 O2.

[0094] Comparative Example 6

[0095] The only difference between Comparative Example 6 and Example 1 is that zirconium dioxide is replaced with magnesium oxide in step (3), while the rest is carried out in the same manner as in Example 1, resulting in a low-valence magnesium-doped high-entropy cathode material for sodium-ion batteries with the chemical formula Na(Ni) 0.3 Fe 0.2 Mn 0.2 Sn 0.1 Cu 0.1 Ti 0.1 ) 0.99 Mg 0.01 O2.

[0096] Comparative Example 7

[0097] The only difference between Comparative Example 7 and Example 1 is that in step (2), the uniform slurry obtained after ball milling is placed in a blower drying oven and dried at a temperature of 100 °C to obtain precursor powder. The rest is carried out in the same way as in Example 1 to obtain sodium-ion battery high-entropy cathode material prepared by conventional solid-state method.

[0098] Comparative Example 8

[0099] The only difference between Comparative Example 8 and Example 1 is that copper oxide is not added in step (1) of Comparative Example 8. The rest is carried out in the same way as in Example 1 to obtain a high-entropy cathode material for sodium-ion batteries with the chemical formula Na(Ni). 1 / 3 Fe 2 / 9 Mn 2 / 9 Sn 1 / 9 Ti 1 / 9 ) 0.99 Zr 0.01 O2.

[0100] Comparative Example 9

[0101] The only difference between Comparative Example 9 and Example 1 is that tin dioxide is not added in step (1) of Comparative Example 9. The rest is carried out in the same manner as in Example 1, resulting in a high-entropy cathode material for sodium-ion batteries with the chemical formula Na(Ni).1 / 3 Fe 2 / 9 Mn 2 / 9 Ti 1 / 9Cu 1 / 9 ) 0.99 Zr 0.01 O2.

[0102] Comparative Example 10

[0103] The only difference between Comparative Example 10 and Example 1 is that in Comparative Example 10, zirconium dioxide was simultaneously mixed with sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, tin dioxide, titanium dioxide, and copper oxide and spray-dried. The zirconium-containing precursor powder obtained by spray drying was then subjected to solid-state sintering. The rest of the process was the same as in Example 1 and will not be repeated here.

[0104] Figure 1 The image shows the XRD pattern of the cathode material prepared in Example 1, confirming that it has a single-phase structure. Figure 2 The images show the SEM and EDS images of the cathode material prepared in Example 1. The SEM images reveal that the primary particles prepared in Example 1 have high roundness. The ratio R of the longest to shortest diagonal length of the orthographic projection of the primary particles is between 1 and 1.4, tending towards a circular shape, and the average grain size of the primary particles is 2 μm. The secondary particles formed by the accumulation of these highly rounded primary particles are spherical, and the secondary particles have an appropriate amount of porosity. The porosity of the secondary particles prepared in Example 1 is approximately 16%. The EDS images show that the elements are uniformly distributed in the cathode material, and no elemental segregation is observed.

[0105] Figure 3 This is the XRD pattern of the cathode material prepared in Comparative Example 1. Figure 4 These are the SEM and EDS images of the cathode material prepared in Comparative Example 1.

[0106] Figure 5 The images show the SEM and EDS images of the cathode material prepared in Comparative Example 7. It can be seen that the cathode material obtained by the traditional solid-state method has an irregular morphology and a rough particle surface.

[0107] Figure 10 The image shows the SEM image of the cathode material prepared in Comparative Example 10. The primary particle size of the cathode material prepared in Comparative Example 10 is relatively large, with an average grain size of 3.2 μm to 6.8 μm, indicating that the introduction of the second metal oxide in one step has no significant effect on suppressing grain coarsening.

[0108] The battery assembly using the cathode materials prepared in the above embodiments and comparative examples specifically includes:

[0109] Preparation of positive electrode sheet: The positive electrode active material (O3 phase layered oxide material prepared in the above examples and comparative examples), conductive agent and binder are mixed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1. After the slurry is magnetically stirred for 6 h, the slurry is uniformly coated on carbon-coated aluminum foil using a coater. The foil is then vacuum dried at 80 ℃ for 12 h. After being punched, the foil is placed in a glove box for later use.

[0110] Electrochemical performance testing: The above-mentioned positive electrode and sodium metal negative electrode were assembled into a half-cell for electrochemical performance testing. A GF / D glass fiber membrane was used as the battery separator. The electrolyte formulation consisted of 1 mol / L sodium hexafluorophosphate (NaPF6) dissolved in ethyl methyl carbonate (EMC) and propylene carbonate (PC) at a volume ratio of 1:1, with 2.0% fluoroethylene carbonate (FEC) added as an electrolyte additive. The constant current charge-discharge test voltage range was 2.0-4.0 V, with a nominal capacity of 150 mAh / g. The rate performance test conditions were: 5 charge-discharge cycles each at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, 8 C, and 10 C. The long-cycle performance test conditions were: 3 charge-discharge cycles at 0.1 C followed by a charge-discharge test at 1 C, and 5 charge-discharge cycles at 0.2 C followed by a charge-discharge test at 5 C.

[0111] Figure 6 This is a rate performance graph based on the battery sample from Example 1. Figure 7 This is a graph showing the long-cycle performance of the battery sample based on Example 1. Figure 8 The figure shows the discharge curves of battery samples based on the cathode materials of Comparative Example 1 and Comparative Example 2. It can be seen from the figure that adding tin as one of the high-entropy components can significantly improve the average discharge plateau of the cathode material. Figure 9 The graphs show the long-cycle performance of the cathode materials based on Comparative Examples 1, 3, and 4. Figure 9 It can be seen that single high-valence cation doping or high-entropy configuration design can improve the cycle performance of cathode materials, but the performance is not as good as the cathode material modified by high-entropy configuration design combined with high-valence cation doping in Example 1.

[0112] The battery performance based on the cathode materials of the above embodiments and comparative examples is summarized in Table 2.

[0113] Table 2. Battery performance based on the cathode materials assembled in the above embodiments and comparative examples.

[0114] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0115] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0116] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A layered oxide material with an O3 phase, characterized in that: The chemical formula of the O3 phase layered oxide material is: Na(Ni) a Fe b Mn c Sn d M e A f ) 1-g B g O2, a=0.2~0.4, b=0.1~0.2, c=0.2~0.4, d=0.05~0.15, e=0.05~0.1, f=0.05~0.15, g=0.005~0.02, a+b+c+d+e+f+g=1; wherein, A is selected from copper and / or magnesium, B is selected from one or more of zirconium, tantalum, tungsten, molybdenum, and niobium, and M is selected from one or more of zinc, aluminum, titanium, and antimony; The O3 phase layered oxide material includes secondary particles formed by the stacking of primary particles. The ratio of the longest diagonal to the shortest diagonal of the orthographic projection profile of the primary particles is defined as R, where 1 ≤ R ≤ 1.4, and the average grain size of the primary particles is 1.8 μm to 2.2 μm. The secondary particles are spherical particles with pores on the surface and inside, and the porosity of the secondary particles is 10% to 25%.

2. The O3 phase layered oxide material according to claim 1, characterized in that: The average diameter of the secondary particles is 30μm~40μm.

3. A method for preparing an O3 phase layered oxide material, characterized in that, include: A uniform mixed slurry containing sodium source, nickel source, iron source, manganese source, tin source, M source and first metal oxide is provided, and centrifugally spray-dried to obtain precursor powder. The precursor powder was mixed with a second metal oxide and solid-state sintered in an oxygen-containing atmosphere to obtain an O3 phase layered oxide material. The first metal oxide includes copper oxide and / or magnesium oxide; the second metal oxide contains a high-valence strongly bonded cation, wherein the valence of the high-valence strongly bonded cation is greater than or equal to tetravalence and the bond energy of the bond formed with the oxygen anion is greater than 600 kJ / mol; the M source provides a metal element M, wherein the metal element M includes one or more of zinc, aluminum, titanium and antimony.

4. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: The first metal oxide includes copper oxide.

5. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: The second metal oxide includes one or a combination of zirconium dioxide, tantalum oxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide.

6. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: The centrifugal spray dryer has an inlet temperature of 130℃~200℃, an outlet temperature of 80℃~130℃, and a centrifugal speed of 10000rpm~18000rpm.

7. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: The solid-state sintering temperature is 850℃~1000℃, and / or the solid-state sintering holding time is 10 h~20 h, and the solid-state sintering heating rate is 1℃ / min~5℃ / min.

8. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: Sodium source, nickel source, iron source, manganese source, tin source, M source, first metal oxide and solvent are mixed and then wet ball milled to form a uniform mixed slurry. The wet ball milling speed is 200 rpm to 800 rpm and the ball milling time is 6 h to 20 h.

9. The method for preparing the O3 phase layered oxide material according to claim 3, characterized in that: The solid content of the mixed slurry is 20% to 40%.

10. The method for preparing the O3 phase layered oxide material according to any one of claims 3-9, characterized in that: The amounts of sodium source, nickel source, iron source, manganese source, tin source, M source, first metal oxide, and second metal oxide used satisfy the chemical formula Na(Ni) a Fe b Mn c Sn d M e A f ) 1-g B g O2, where A represents copper and / or magnesium provided by the first metal oxide, B represents a high-valence, strongly bonded cation provided by the second metal oxide, a=0.2~0.4, b=0.1~0.2, c=0.2~0.4, d=0.05~0.15, e=0.05~0.1, f=0.05~0.15, g=0.005~0.02, a+b+c+d+e+f+g=1.

11. An O3 phase layered oxide material, characterized in that, It is prepared by the method for preparing O3 phase layered oxide material according to any one of claims 3-10.

12. A positive electrode for a sodium-ion battery, characterized in that, It includes a positive electrode active material, wherein the positive electrode active material includes the O3 phase layered oxide material as described in any one of claims 1, 2, and 11.

13. A sodium-ion battery, characterized in that, The positive electrode of the sodium-ion battery is the positive electrode for the sodium-ion battery according to claim 12.

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