A plate-shaped tunnel structure potassium titanate lithium battery anode material, its preparation method and application

Abstract

The present invention relates to the field of material preparation, and discloses a potassium titanate lithium battery anode material with a plate-like tunnel structure, its preparation method and application. The preparation method includes: treating potassium iron titanate K 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 with a low-concentration acid solution, followed by filtration, washing, and drying to obtain potassium titanate K 0.4‑m H 0.3+ m Fe 0.7 Ti 1.3 O4 (0 < m < 0.4); performing heat treatment on the layered potassium titanate K 0.4‑m H 0.3+ m Fe 0.7 Ti 1.3 O4 to obtain plate-like K x Fe y Ti 8‑y O 16 (where x = 0.1 - 1.2, y = 0.5 - 6.2) with exposed (001) crystal plane of the tunnel structure. The preparation method provided by the present invention uses layered K 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 as a precursor, and through a soft chemical in-situ topological transformation reaction, by controlling the heat treatment temperature, plate-like K x Fe y Ti 8‑y O 16 particles are prepared. They have small particle size and narrow distribution. Compared with the reported molten salt method and co-precipitation method, the K x Fe y Ti 8‑y O 16 prepared by the technology of the present invention has small particle size, controllable morphology and microstructure, and its preparation process is simple, with low energy consumption and high repeatability, which is conducive to industrial production.

Description

Technical Field

[0001] This invention relates to the field of materials preparation, specifically to a plate-like tunnel structure potassium titanate lithium battery anode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, due to their high specific capacity and good cycle stability, have been widely used in mobile devices, electric vehicles, and other fields. The electrochemical performance of lithium-ion batteries mainly depends on their electrode materials, including the positive and negative electrodes. In recent years, researchers have made many efforts to improve battery materials so that they can be used in electric vehicles. Conventional lithium-ion batteries use graphite as the negative electrode material because of its abundant reserves. However, graphite performs poorly at high charge / discharge rates and poses safety issues due to the formation of lithium dendrites caused by the low lithium-ion intercalation potential. One way to solve this problem is to find carbon-based materials that combine high-rate performance and safety. Titanium-based materials, such as TiO2 and Li4Ti5O2, are examples. 12 It exhibits good cyclic stability and safety. The K-shaped tunnel structure... x Fe y Ti 8-y O 16 It is a zero-strain material with potential applications in lithium-ion batteries. Currently, K... x Fe y Ti 8-y O 16 The main synthesis methods for K include the molten salt method and the solid-state method. However, the currently obtained K... x Fe y Ti 8-y O 16 All of them have a rod-shaped morphology and do not expose the (001) tunnel surface that is conducive to lithium ion migration. Summary of the Invention

[0003] To overcome the shortcomings of the existing technology, the present invention aims to provide a method for preparing and applying a plate-like tunnel structure potassium titanate lithium battery anode material, and the K... x Fe y Ti 8-y O 16 With small particle size, controllable morphology and microstructure, it can achieve high specific capacity in batteries, and its ion exchange is controllable, allowing selective transfer of K+ between precursor layers. + Partial exchange. Experiments show that the K prepared by this method... x Fe y Ti 8-y O 16 It exhibits better electrochemical performance compared to rod-shaped structures.

[0004] To achieve the above object, on the one hand, the present invention provides a preparation method of a potassium titanate lithium battery anode material with a plate-shaped tunnel structure, which includes the following steps: treating potassium iron titanate K 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 with a low-concentration acid solution, followed by filtration, washing, and drying to obtain layered potassium titanate K 0.4-m H 0.3+m Fe 0.7 Ti 1.3 O4 (0 < m < 0.4); then heat-treating the layered potassium titanate K 0.4-m H 0.3+m Fe 0.7 Ti 1.3 O4 at 400 - 800 °C to obtain a plate-shaped K x Fe y Ti 8-y O 16 (where x = 0.1 - 1.2, y = 0.5 - 6.2) with an exposed (001) crystal plane tunnel structure, which is the potassium titanate lithium battery anode material with a plate-shaped tunnel structure.

[0005] As a further preferred technical solution of the present invention, the acid solution is at least one of acetic acid, hydrochloric acid, and sulfuric acid solution.

[0006] As a further preferred technical solution of the present invention, the concentration of the acid solution is 0.1 - 2 mol / L.

[0007] According to another aspect of the present invention, the present invention also provides a potassium titanate lithium battery anode material with a plate-shaped tunnel structure, which is prepared by the above method.

[0008] As a further preferred technical solution of the present invention, the length of the potassium titanate lithium battery anode material is 1 - 2 μm, and the thickness is 20 - 50 nm.

[0009] According to yet another aspect of the present invention, the present invention also provides an application of a potassium titanate lithium battery anode material with a plate-shaped tunnel structure in a lithium-ion battery.

[0010] As a further preferred technical solution of the present invention, the potassium titanate lithium battery anode material, acetylene black, and polyvinylidene fluoride are mixed in a mass ratio of 70 - 80:10 - 15:5 - 10, and after adding the solvent N-methylpyrrolidone, they are ground into a slurry and evenly coated on a conductive metal sheet to be used as the anode of a lithium-ion battery.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The preparation method provided by the present invention uses layered K 0.4 H0.3 Fe 0.7 Ti 1.3 Using O4 as a precursor, a plate-like K2 structure was prepared by utilizing a soft chemical in-situ topological transformation reaction and controlling the heat treatment temperature. x Fe y Ti 8-y O 16 The particles are small in size and narrowly distributed (length approximately 1–2 μm, thickness 20–50 nm); compared to the reported molten salt method and co-precipitation method, the K particles prepared by the present invention are superior. x Fe y Ti 8- y O 16 With small particle size, controllable morphology and microstructure, and a simple preparation process with low energy consumption and high repeatability, it is conducive to industrial production. Plate-shaped K x Fe y Ti 8-y O 16 The particles can be used as negative electrode materials in lithium-ion batteries and have shown good electrochemical performance. Attached Figure Description

[0013] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0014] Figure 1 XRD patterns of the potassium titanate lithium battery anode materials obtained in Examples 1-4 and Comparative Example 1: (a) plate-shaped particles; (b) rod-shaped particles.

[0015] Figure 2 SEM images of the plate-like particles obtained after heat treatment at different temperatures in Examples 1-4: (a) 500℃; (b) 600℃; (c) 700℃; (d) 800℃.

[0016] Figure 3 Characterization of the obtained crystal structures: (ac) plate-like particles (Example 1); (df) rod-like particles (Example 5).

[0017] Figure 4 The graph shows the cycling performance of plate-shaped and rod-shaped particles after 100 cycles at a current density of 100 mA / g.

[0018] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0021] The layered potassium iron titanate K used in this invention 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 can be prepared using a hydrothermal method for preparing iron-containing layered potassium titanate plate-like particles, as disclosed in Chinese Patent Application No. 201710743855.7.

[0022] The layered potassium iron titanate K used in the following examples 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 is prepared by the following method, as detailed below:

[0023] 5g of titanium dioxide, 16.87g of ferric nitrate nonahydrate, and 20g of potassium hydroxide were added to 18mL of water and mixed thoroughly. The mixture was then transferred to a hydrothermal reactor and hydrothermated at 250℃ for 24 hours. After filtration, washing, and drying at room temperature, the resulting product was obtained as layered potassium ferric titanate K. 0.4 H 0.3 Fe 0.7 Ti 1.3 O4.

[0024] Example 1

[0025] The potassium titanate lithium battery anode material and the method for preparing a lithium-ion battery using the potassium titanate lithium battery anode material provided in this embodiment are as follows:

[0026] 1) Add 0.2g of layered potassium iron titanate K 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 was added to a 0.5 mol / L acetic acid solution and stirred at room temperature for 12 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain layered K. 0.2 H 0.5 Fe 0.7 Ti 1.3 O4, then calcined the product in a muffle furnace at 500°C for 3 hours to obtain a plate-shaped potassium titanate lithium battery anode material. 0.5 Fe 2.2 Ti 5.8 O 16 The particles are approximately 1–2 μm long and 20–50 nm thick, with a smooth, plate-like surface.

[0027] 2) Place the plate-shaped K 0.5 Fe 2.2 Ti 5.8 O 16 Particles, acetylene black, and polyvinylidene fluoride were mixed in a mass ratio of 70:20:10. After adding N-methylpyrrolidone, the mixture was ground and uniformly coated onto a copper sheet to serve as the negative electrode of a lithium-ion battery. The positive electrode was metallic lithium, and the electrolyte was a 1 mol / L LiPF6 EC+DEC+DMC solution (EC / DEC / DMC = 1 / 1 / 1, v / v / v). The battery was then assembled in a glove box. After assembly, the battery's rate capability, cycle life, and other performance characteristics were tested using an electrochemical workstation.

[0028] Example 2

[0029] Based on Example 1, the only difference from Example 1 is that the calcination temperature in the muffle furnace is replaced with 600℃, while other operations and processes remain the same. The potassium titanate lithium battery anode material obtained in Example 2 is a plate-shaped K... 0.8 Fe 2.2 Ti 5.8 O 16 Its length is about 1 to 2 μm and its thickness is 20 to 50 nm, with a smooth plate-like surface.

[0030] Example 3

[0031] Based on Example 1, the only difference from Example 1 is that the calcination temperature in the muffle furnace is replaced with 700°C, while other operations and processes remain the same. The potassium titanate lithium battery anode material obtained in Example 3 is plate-shaped KFe. 2.5 Ti 5.5 O 16 Its length is about 1 to 2 μm and its thickness is 20 to 50 nm. The plate-like surface is smooth, the plate-like surface is rough and has obvious particles. It is a mesocrystalline material composed of nanocrystals.

[0032] Example 4

[0033] Based on Example 1, the only difference from Example 1 is that the calcination temperature in the muffle furnace is replaced with 800℃, while other operations and processes remain the same. The potassium titanate lithium battery anode material obtained in Example 3 is a plate-shaped K... 1.2 Fe 1.8 Ti 6.2 O 16 Its length is approximately 1–2 μm and its thickness is 20–50 nm.

[0034] Comparative Example 1

[0035] As a control experiment for Examples 1-4, the specific method is as follows:

[0036] 1) Add 2g of layered potassium iron titanate K0.4 H 0.3 Fe 0.7 Ti 1.3 O4 was added to a 4 mol / L hydrochloric acid solution and stirred at room temperature for 12 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain rod-shaped K. 1.5 Fe 1.5 Ti 5.5 O 16 The particles are approximately 1–2 μm long and 20–50 nm in diameter.

[0037] 2) Place the rod-shaped K 1.5 Fe 1.5 Ti 5.5 O 16 Particles, acetylene black, and polyvinylidene fluoride were mixed in a mass ratio of 70:20:10. After adding N-methylpyrrolidone, the mixture was ground and uniformly coated onto a copper sheet to serve as the negative electrode of a lithium-ion battery. The positive electrode was metallic lithium, and the electrolyte was a 1 mol / L LiPF6 EC+DEC+DMC solution (EC / DEC / DMC = 1 / 1 / 1, v / v / v). The battery was then assembled in a glove box. After assembly, the battery's rate capability, cycle life, and other performance characteristics were tested using an electrochemical workstation.

[0038] A detailed comparison of Examples 1-4 and Comparative Example 1 is shown in Table 1.

[0039] Table 1

[0040]

[0041] Note: The K ion content of the plate-like particle products obtained in Examples 1-4 increases sequentially, that is, the tunnels are gradually filled with K ions.

[0042] See Figure 1 K is prepared from Examples 1-4 x Fe y Ti 8-y O 16 XRD patterns of plate-like particles (Examples 1-4). Figure 1 (a) XRD patterns of plate-shaped particles obtained by heat treatment at different temperatures (500-800℃ corresponding to Examples 1-4, respectively). As can be seen from the figure, with increasing heat treatment temperature, the relative intensities of the diffraction peaks corresponding to 2θ = 12.5° and 17.5° gradually decrease, indicating that the K ion content in the tunnels increases accordingly, and the K tunnels gradually approach a filled state. Figure (b) shows the K ion content of rod-shaped particles obtained after treatment with 4 mol / L hydrochloric acid in Comparative Example 1. 1.5 Fe 1.5 Ti 5.5 O 16 The XRD pattern, its diffraction peaks and Figure 1(a) The diffraction peaks at 800℃ are similar, indicating that the K ions in the rod-shaped particle tunnels are in a filled state.

[0043] See Figure 2 K is prepared by heat treatment at different temperatures in Examples 1-4. x Fe y Ti 8-y O 16 SEM images of plate-like particles (500-800℃ corresponding to Examples 1-4 respectively). It can be clearly seen from the images that the K obtained in this invention... x Fe y Ti 8-y O 16 The particles are plate-shaped, with a length of approximately 1–2 μm and a thickness of 20–50 nm. After heat treatment at 500–700 °C, the plate-shaped surface is smooth, while after heat treatment at 800 °C, particles appear on the surface, indicating that the plate-shaped particles are mesocrystalline composed of nanocrystals.

[0044] See Figure 3 ,from Figure 3 In (c), two sets of crystal planes of the plate-like particles can be observed, namely (2-20) and (0-40). According to the zone law, the crystal axis parallel to the transmitted incident electron beam is

[001] . Therefore, the exposed crystal plane is (001). Similarly, in Figure 3 (c) The (200) and (501) crystal planes of the rod-shaped particles are determined to be parallel to the transmitted incident electron beam as

[010] according to the zone law. Therefore, the exposed crystal plane is (010).

[0045] See Figure 4 , Figure 4 For K 0.5 Fe 2.2 Ti 5.8 O 16 Plate-shaped particles (Example 1) and K 1.5 Fe 1.5 Ti 5.5 O 16 Rod-shaped particles (Comparative Example 1) at a current density of 100 mAg -1 The cycling curves below show that after 100 cycles, the specific capacity of the plate-shaped particles is 300 mAh / g, while the specific capacity of the rod-shaped particles is only 100 mAh / g. It can be seen that the plate-shaped particles exhibit a higher specific capacity than the rod-shaped particles. The electrochemical performance of the plate-shaped particles with exposed (001) crystal planes is better than that of the rod-shaped particles with exposed (010) crystal planes, because the exposed crystal planes of the plate-shaped particles correspond to tunnel planes, which are conducive to lithium ion migration.

[0046] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a plate-like tunnel structured potassium titanate lithium battery anode material, characterized in that, Includes the following steps: Layered potassium iron titanate K 0.4 H 0.3 Fe 0.7 Ti 1.3 O4 is treated with a low-concentration acid solution, then filtered, washed, and dried to obtain layered titanate K. 0.4-m H 0.3+m Fe 0.7 Ti 1.3 O4, 0 <m<0.4; Then, for layered titanate K 0.4-m H 0.3+m Fe 0.7 Ti 1.3 O4 was heat-treated at 400-800℃ to obtain plate-like K with a tunnel structure exposing (001) crystal planes. x Fe y Ti 8-y O 16 Where x = 0.1~1.2 and y = 0.5~6.2, it is the potassium titanate lithium battery anode material with a plate-like tunnel structure; The acid solution is at least one of acetic acid, hydrochloric acid, and sulfuric acid solution.

2. The method for preparing the plate-like tunnel structure potassium titanate lithium battery anode material according to claim 1, characterized in that, The concentration of the acid solution is 0.1~2 mol / L.

3. A plate-like tunnel structure potassium titanate lithium battery anode material, characterized in that, It is prepared by the method according to any one of claims 1 or 2.

4. The potassium titanate lithium battery anode material with a plate-like tunnel structure according to claim 3, characterized in that, The potassium titanate lithium battery anode material has a length of 1~2 μm and a thickness of 20~50 nm.

5. The application of the potassium titanate lithium battery anode material with a plate-like tunnel structure as described in claim 3 in lithium-ion batteries.

6. The application according to claim 5, characterized in that, Potassium titanate lithium battery anode material, acetylene black, and polyvinylidene fluoride are mixed in a mass ratio of 70~80:10~15:5~10, and N-methylpyrrolidone solvent is added. The mixture is then ground into a slurry and uniformly coated onto a conductive metal sheet to serve as the anode of a lithium-ion battery.

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