Method for directly regenerating oxyfluoride positive electrode material of sodium ion battery

Abstract

The invention innovatively provides a method for directly regenerating a novel sodium-electrode layered oxyfluoride positive electrode material from a ternary lithium ion battery positive electrode material, aiming at the field of waste ternary lithium ion battery recovery. According to the process, a mechanical activation-solid phase sintering combined technology is adopted, lithium is selectively extracted through ammonium sulfate, a sodium source and a manganese source are mixed to realize transition metal oxide in-situ conversion, and finally, a novel sodium electric oxyfluoride positive electrode material NaxLiyNizCotMnmO2-nF2n at-AaBbCcDdEeFf with a stable layered structure is prepared by gradient doping and surface coating of high-valence high-entropy fluoride. Compared with a traditional recycling method, the technology achieves the three-in-one breakthrough of lithium battery recycling, material regeneration and performance optimization, and the obtained material has remarkable advantages in the aspect of structural stability. The process provides a new high-valued utilization way of the retired lithium battery material, has both environmental benefits and economic benefits, and provides an innovative scheme for constructing a closed-loop system of a new energy industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of recycling waste ternary battery materials, and particularly relates to a method for directly regenerating a sodium-ion battery fluorine oxide cathode material. Background Art

[0002] With the proposal of the strategic goals of "carbon peak" and "carbon neutrality" in China, lithium-ion batteries, due to their characteristics of clean energy, are widely used in electronic products such as portable devices and electric vehicles. However, the short service life of lithium-ion batteries has led to an increasing number of waste lithium-ion batteries in recent years, which contain a large amount of toxic compounds and valuable metals. Therefore, the recycling of waste lithium-ion batteries has great economic and environmental benefits.

[0003] Sodium and lithium have similar physical and chemical properties, have relatively rich reserves in nature, and sodium-ion batteries also have a similar working principle to lithium-ion batteries. Therefore, sodium-ion batteries are considered to be one of the most promising alternatives to lithium-ion batteries. At the same time, high-valence high-entropy fluorides can be used as doping sources and coating sources, and mixed with the O3-layered cathode material of sodium-ion batteries to form a fluorine oxide cathode material, optimizing the interfacial electronic structure, reducing the interfacial contact resistance, suppressing lattice distortion and improving the electron and ion transport rates.

[0004] CN117223124A discloses a cathode material co-modified by high-entropy oxide doping and coating, a preparation method and an application thereof. The process is prepared through a process of hydrothermal high-entropy attachment - substrate molten salt mixing - sodium source addition and sintering. However, this material still has an interfacial stress problem. During long-term cycling, the coated high-entropy oxide may not be able to effectively adapt to the volume change of the cathode material, gradually peel off during the cycling process, and cause the generation of cracks in the material, reducing the battery life. At the same time, during high-voltage charge and discharge, the transition metal in the layered material may undergo redox reactions, resulting in the release of O2, causing problems such as structural instability and electrolyte decomposition.

[0005] In summary, directly regenerating the cathode material of waste ternary lithium-ion batteries into a sodium-ion battery fluorine oxide cathode material has great development prospects. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the present invention proposes a method with a short process flow, which can directly regenerate the cathode material of waste ternary lithium-ion batteries into a sodium-ion battery fluorine oxide cathode material with excellent performance and stability.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] The present invention provides a method for directly regenerating a sodium-ion battery fluorine oxide cathode material, and the preparation method includes the following steps:

[0009] (1) Mix the waste ternary cathode powder and ammonium sulfate in a certain ratio and carry out mechanical ball milling activation to achieve uniform compounding;

[0010] (2) Carry out high-temperature calcination in a tubular furnace, extract lithium by water leaching after cooling, and filter and dry to prepare a transition metal oxide solid;

[0011] (3) Mix the transition metal oxide solid, sodium carbonate, manganese dioxide and fluoride in a certain molar ratio. The mixture is activated by mechanical ball milling to achieve uniform compounding;

[0012] (4) Carry out solid-phase sintering in a muffle furnace to obtain a novel sodium-ion layered fluorinated oxide cathode material with partial doping and coating of high-valence high-entropy fluoride Na x Li y Ni z Co t Mn m O 2-n F 2n @A a B b C c D d E e F f 。

[0013] Preferably, the mass ratio of the waste cathode to ammonium sulfate in step (1) is 1-10:1-8.

[0014] Preferably, the ball milling time in step (1) is 1-12 h, and the ball milling speed is 100-800 rpm.

[0015] Preferably, the atmosphere in the tubular furnace in step (2) is Ar / N2 or N2, the calcination time is 1-10 h, the heating rate during the calcination process is 1-10 °C / min, and the calcination temperature is 500-1000 °C.

[0016] Preferably, the ultrasonic water leaching duration in step (2) is 10-30 min, and the drying temperature is 60-120 °C.

[0017] Preferably, the fluoride in step (3) is A a B b C c D d E e F f, where 0.05 < a < 0.3, 0.05 < b < 0.3, 0.05 < c < 0.3, 0.05 < d < 0.3, 0.05 < e < 0.3, 0 < f ≤ 6, and a + b + c + d + e = 1, and A, B, C, D, and E are selected from five of Ti, Zr, Hf, Sn, Ce, Mn, Ru, Nb, Ta, Sb, V, Mo, W, and U.

[0018] Preferably, the molar ratio of the transition metal oxide solid, sodium carbonate, manganese sesquioxide, and fluoride in step (3) is 1 to 3: 1 to 5: 0.1 to 1: 0.01 to 0.1, the ball milling time is 1 to 12 h, and the ball milling speed is 100 - 800 rpm.

[0019] Preferably, the sintering time in step (4) is 12 to 24 h, the heating rate during the calcination process is 1 to 10 °C / min, and the calcination temperature is 500 to 1000 °C.

[0020] Preferably, the novel sodium-based layered fluorinated oxide cathode material in step (4) is Na x Li y Ni z Co t Mn m O 2-n F 2n @A a B b C c D d E e F f , where 1 < x < 2, 0.01 ≤ y < 0.2, 0.3 < z < 0.6, 0.05 < t < 0.3, 0.3 < m < 0.6, 0.001 < n < 0.05.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Based on the recycling of waste ternary lithium-ion cathode materials, the lithium salts and sodium-based layered fluorinated oxide cathode materials produced have extremely high economic and environmental benefits. The recycling process is simple, and there is no need to separate impurity elements during the process. Instead, they are directly used to improve the performance of the sodium-ion battery cathode material, which is easy to scale up and industrialize.

[0023] (2) Compared with the traditional direct regeneration method, the present invention uses an improved sintering process with high-entropy fluoride as a coating agent and doping agent to achieve partial doping and coating of high-entropy fluoride, obtaining a controllable coating layer. Compared with direct coating, it not only avoids the problem of the thick coating layer affecting the electron transport rate but also optimizes the crystal structure by doping with F element, greatly enhancing the stability of the layered structure of the recycled sodium-ion battery cathode material.

[0024] (3) Compared with the high-entropy oxide coating, F in the high-entropy fluoride - can replace the lattice oxygen vacancies existing in the recycled material to form F-M-O bonds, which are more stable than M-O bonds, can effectively reduce O2 release, and improve high-voltage stability. At the same time, F - can gradually diffuse into the material body to form a gradient structure and induce Na + to change the diffusion channels, reduce stress accumulation, inhibit the O3→P3 phase transition, enhance the phase structure stability, and improve the cycle life. Description of the Drawings

[0025] Figure 1 It is a test chart of the electrochemical performance of the coated recycled material prepared in Example 1.

[0026] Figure 2 It is a test chart of the electrochemical performance of the uncoated recycled material prepared in Comparative Example 1. Detailed Embodiments

[0027] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0028] Example 1

[0029] This example provides a method for directly recycling a fluorine oxide cathode material for a sodium-ion battery. The composition of the cathode material is Na 1.1 Li 0.01 Ni 0.43 Co 0.14 Mn 0.43 O 1.99 F 0.02 @Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 F5, and the preparation method includes the following steps:

[0030] (1) Take 5 g of waste ternary cathode powder and 3 g of ammonium sulfate and add them to a ball milling jar, then put it into a ball mill and grind for 6 h at a rotation speed of 600 r / min to obtain a uniformly mixed powder material;

[0031] (2) Take 5 g of the powder and put it into a small porcelain boat, and place it in the middle part of the furnace tube of a tube furnace. Under an N2 atmosphere, heat it to 800 °C at a heating rate of 5 °C / min and hold for 2 h;

[0032] (3) Put the obtained composite material into a beaker, add 500 mL of deionized water at the same time, extract part of the Li, after treating for 10 min under ultrasonic conditions, carry out suction filtration, and dry the filter cake in an oven at 100 °C to obtain a transition metal oxide solid;

[0033] (4) Mix the transition metal oxide solid, sodium carbonate, manganese sesquioxide and fluoride in a molar ratio of 1:1.1:0.3:0.03, add them to a ball milling tank, put it into a ball mill, and grind at a rotation speed of 400 r / min for 10 h to obtain a uniformly mixed powder material;

[0034] (5) Take 5 g of the powder material and put it into a small porcelain boat, and place it in the middle part of a muffle furnace, heat it to 800 °C at a heating rate of 3 °C / min, and keep it for 12 h to obtain the cathode material Na 1.1 Li 0.01 Ni 0.43 Co 0.14 Mn 0.43 O 1.99 F 0.02 @Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 F5;

[0035] (6) Perform electrochemical performance tests at room temperature. The results show ( Figure 1 ), after 100 cycles, the specific capacity still remains 133.6 mAh / g, showing high specific capacity and good cycle stability.

[0036] Example 2

[0037] This example provides a method for directly regenerating a fluoride oxide cathode material for a sodium-ion battery. The composition of the cathode material is Na 1.05 Li 0.01 Ni 0.41 Co 0.14 Mn 0.45 O 1.995 F 0.01 @Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 F5, and the preparation method includes the following steps:

[0038] (1) Take 7 g of waste ternary cathode powder and 4 g of ammonium sulfate, add them to a ball milling tank, put it into a ball mill, and grind at a rotation speed of 400 r / min for 8 h to obtain a uniformly mixed powder material;

[0039] (2) Put 5 g of the powder material into a small porcelain boat and place it in the middle part of the tube furnace. Under an Ar / N2 atmosphere, heat it to 700 °C at a heating rate of 3 °C / min and hold for 2 h;

[0040] (3) Put the obtained composite material into a beaker, add 500 mL of deionized water at the same time, extract Li, after treating it for 20 min under ultrasonic conditions, carry out suction filtration, and dry the filter cake in an oven at 120 °C to obtain a transition metal oxide solid;

[0041] (4) Mix and add the transition metal oxide solid, sodium carbonate, manganese sesquioxide and fluoride into the ball milling tank according to the molar ratio of 1:1.05:0.35:0.02, put it into the ball mill, and grind it at a rotation speed of 400 r / min for 10 h to obtain a uniformly mixed powder material;

[0042] (5) Take 5 g of the powder material and put it into a small porcelain boat, and place it in the middle part of the muffle furnace. Heat it to 850 °C at a heating rate of 5 °C / min and hold for 16 h to obtain the cathode material Na 1.05 Li 0.01 Ni 0.41 Co 0.14 Mn 0.45 O 1.995 F 0.01 @Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 F5.

[0043] Comparative Example 1

[0044] This comparative example provides a method for directly regenerating the cathode material of a sodium-ion battery. Except that fluoride is not mixed in the transition metal oxide mixing stage, the rest are the same as in Example 1. The obtained cathode material is Na 1.1 Li 0.01 Ni 0.43 Co 0.14 Mn 0.43 O2. The test results of the electrochemical performance show ( Figure 2 ), after 100 cycles, the specific capacity is 102.2 mAh / g, showing a poor specific capacity.

Claims

1. A method for directly regenerating a sodium-ion battery fluorine oxide cathode material, characterized in that, It includes the following steps: (1) Mix waste ternary cathode powder with ammonium sulfate in a certain proportion and carry out mechanical ball milling activation to achieve uniform compounding; (2) Conduct high-temperature calcination in a tube furnace, leach lithium with water after cooling, and filter and dry to prepare a transition metal oxide solid; (3) Mix the transition metal oxide solid, sodium carbonate, manganese dioxide and fluoride in a certain molar ratio. The mixture is activated by mechanical ball milling to achieve uniform compounding; (4) Solid-phase sintering is carried out in a muffle furnace to obtain a novel sodium-ion battery layered fluorinated oxide cathode material with partial doping and coating of high-valence high-entropy fluorides, Na x Li y Ni z Co t Mn m O 2-n F 2n @A a B b C c D d E e F f .

2. The method for preparing a fluorine oxide cathode material for a direct-rechargeable sodium ion battery according to claim 1, wherein In step (1), the mass ratio of the waste cathode to ammonium sulfate is 1-10:1-8.

3. A method for a fluorine oxide cathode material of a direct regeneration sodium ion battery according to claims 1-2, characterized in that, In step (1), the ball milling time is 1-12 h, and the ball milling speed is 100-800 rpm.

4. A method for directly regenerating a fluorine oxide cathode material of a sodium ion battery according to claims 1-3, characterized in that, In step (2), the atmosphere in the tube furnace is Ar / N2 or N2, the calcination time is 1-10 h, the heating rate during the calcination process is 1-10 °C / min, and the calcination temperature is 500-1000 °C.

5. A method for directly regenerating a fluorine oxide cathode material of a sodium ion battery according to claims 1-4, characterized in that, In step (2), the ultrasonic water leaching time is 10-30 min, and the drying temperature is 60-120 °C.

6. A method for directly regenerating a fluorine oxide cathode material of a sodium ion battery according to claims 1-5, characterized in that, The fluoride described in step (3) is A a B b C c D d E e F f , where 0.05 < a < 0.3, 0.05 < b < 0.3, 0.05 < c < 0.3, 0.05 < d < 0.3, 0.05 < e < 0.3, 0 < f ≤ 6, and a + b + c + d + e = 1, and the A, B, C, D, and E are selected from five of Ti, Zr, Hf, Sn, Ce, Mn, Ru, Nb, Ta, Sb, V, Mo, W, and U.

7. A method for directly regenerating a fluorine oxide cathode material for a sodium ion battery according to claims 1-6, characterized in that, In step (3), the molar ratio of the transition metal oxide solid, sodium carbonate, manganese dioxide and fluoride is 1-3:1-5:0.1-1:0.01-0.1, the ball milling time is 1-12 h, and the ball milling speed is 100-800 rpm.

8. A method for directly regenerating a fluorine oxide cathode material for a sodium ion battery according to claims 1-7, characterized in that, In step (4), the sintering time is 12-24 h, the heating rate during the calcination process is 1-10 °C / min, and the calcination temperature is 500-1000 °C.

9. A method for directly regenerating a fluorine oxide cathode material for a sodium ion battery according to claims 1-8, characterized in that, The novel sodium-based layered fluorine oxide cathode material described in step (4) is Na x Li y Ni z Co t Mn m O 2-n F 2n @A a B b C c D d E e F f , where 1 < x < 2, 0.01 ≤ y < 0.2, 0.3 < z < 0.6, 0.05 < t < 0.3, 0.3 < m < 0.6, 0.001 < n < 0.05.

Images