A non-gas-producing lithium-rich lithium iron ferrite cathode material, its preparation method and application

Abstract

The present application relates to a kind of non-gas type lithium-rich lithium iron phosphate anode lithium supplement material and its preparation method and application, using ordinary lithium-rich lithium iron phosphate as raw material, lithium-rich lithium iron phosphate, sulfur or phosphorus element and to conductive agent are ball milled, and heated at high temperature, so that sulfur or phosphorus element and conductive agent are mixed uniformly, and coated on the surface of lithium-rich lithium iron phosphate, finally obtain composite material.Compared with prior art, the lithium supplement material of the present application is added to the positive electrode slurry, not only can realize the purpose of positive electrode prelithiation, but also can inhibit the oxygen release problem of lithium-rich lithium iron phosphate lithium supplement agent during charging.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery lithium replenishment technology, and relates to a non-gas-producing lithium-rich lithium iron phosphate cathode lithium replenishment material, its preparation method and application. Background Technology

[0002] With the continuous progress and development of the new energy industry, the important field of lithium-ion batteries has received widespread attention. As one of the main research hotspots, pre-lithiation technology is a very promising technology direction for lithium-ion batteries.

[0003] During the charging and discharging process, lithium-ion batteries inevitably consume a limited number of lithium ions due to the formation of the SEI (Sediment Intercalation Zone), resulting in irreversible lithium loss. This poses challenges and risks to the battery's cycle life and coulombic efficiency. Lithium replenishment technology is a very effective solution to this problem.

[0004] Currently, the most popular lithium replenishment technologies are positive electrode lithium replenishment and negative electrode lithium replenishment. Negative electrode lithium replenishment has seen some development, but because it involves the use of metallic lithium, which readily reacts with water in air and has high environmental requirements, its large-scale application faces significant challenges. In contrast, positive electrode lithium replenishment is a simple and effective method, requiring only the addition of an appropriate amount of lithium replenishing agent during the positive electrode homogenization process.

[0005] Lithium-rich lithium iron phosphate (LFP) has great potential as a cathode lithium supplement. Its theoretical specific capacity can reach 690 mAh / g, far exceeding that of the more commonly used lithium nickel oxide (LiNiO) supplement. However, LFP also has a significant problem: oxygen is inevitably generated during charging, posing a potential hazard to the battery. This is the main reason why LFP is currently difficult to use on a large scale. Summary of the Invention

[0006] The purpose of this invention is to provide a non-gas-producing lithium-rich lithium ferrite cathode lithium replenishment material, its preparation method and application, so as to solve the problem that the commonly used lithium replenishment agent, lithium-rich lithium ferrite, produces gas and is difficult to apply on a large scale.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a non-gas-generating lithium-rich lithium iron phosphate cathode lithium replenishment material, comprising the following steps:

[0009] (1) Take lithium iron ferrite (Li5FeO4), sulfur or phosphorus, and conductive agent and grind them to make them evenly mixed to obtain a mixture.

[0010] (2) The mixture is ball-milled and then heated and kept warm so that sulfur or phosphorus is adsorbed on Ketjen black and coated on the surface of lithium iron ferrite to obtain the target product.

[0011] Furthermore, the grinding in step (1) is carried out in a dry atmosphere with the relative humidity kept below 10%.

[0012] Furthermore, in step (1), the conductive agent accounts for 2 to 10% of the mass of the mixture.

[0013] Furthermore, in step (1), the molar ratio of lithium iron ferrite to sulfur or phosphorus is 1:1.

[0014] Furthermore, in step (1), the conductive agent is Ketjen black, carbon black, or carbon nanotubes, etc.

[0015] Furthermore, in step (2), during the ball milling process, the mass ratio of the grinding media to the grinding beads is 1:(8-12).

[0016] Furthermore, in step (2), the ball milling speed is 150-500 rpm, preferably 150-250 r / min, and the time is 2-10 h, preferably 2-4 h.

[0017] Furthermore, in step (2), both the ball milling and heating and heat preservation processes are carried out in an inert atmosphere, with an oxygen concentration of less than 10 ppm and a water vapor concentration of less than 0.2 ppm.

[0018] Furthermore, in step (2), when the mixture is made of lithium iron ferrite rich in lithium, elemental sulfur and conductive agent, it is heated to 130-170°C and kept at that temperature for 1-3 hours.

[0019] Furthermore, in step (2), when the mixture is made of lithium iron ferrite, elemental phosphorus and conductive agent, it is first heated to 400-500°C and kept at that temperature for 1-3 hours, and then kept at 200-300°C for 24-72 hours.

[0020] This invention uses common lithium iron ferrite as raw material. The lithium iron ferrite, elemental sulfur or phosphorus, and a conductive agent are ball-milled and then heated at high temperature. This ensures uniform adsorption of the sulfur or phosphorus and Ketjen black, which then coat the surface of the lithium iron ferrite, resulting in a composite material. Ball milling not only reduces the particle size of the lithium iron ferrite but also ensures more uniform contact among the three components. Adding this composite material to the positive electrode slurry not only achieves pre-lithiation of the positive electrode but also suppresses oxygen release from the lithium iron ferrite supplementary agent during charging. Since lithium iron ferrite releases lithium ions through the oxidation of oxygen anions, the addition of elemental sulfur or phosphorus, using sulfur or phosphorus as the oxidation active site, replaces the oxidation of oxygen anions into oxygen, reducing the impact of gas generation from the supplementary agent on the battery itself.

[0021] Furthermore, this invention has found that if sulfur and lithium-rich lithium iron ferrite are ball-milled directly without the use of Ketjen black, sulfur or phosphorus (P) will be uniformly distributed around the lithium iron ferrite after ball milling. However, due to the poor conductivity of sulfur or P, even when the final ball-milled sample is added to the positive electrode, sulfur or P will not only fail to react with the lithium iron ferrite but will also hinder the capacity utilization of the lithium iron ferrite to some extent. Therefore, Ketjen black, due to its strong conductivity and large specific surface area, plays a crucial role in promoting the reaction between lithium-rich lithium iron ferrite and sulfur or P.

[0022] In addition, this invention investigated the effect of ball milling conditions on the composite material. Ball milling mainly involves crushing lithium-rich lithium iron ferrite particles that are tens of micrometers in size, reducing the particle size of lithium-rich lithium iron ferrite to the level of a few micrometers, and uniformly mixing the raw materials.

[0023] In a second aspect, the present invention provides a non-gas-producing lithium-rich lithium iron phosphate cathode lithium replenishment material, which is prepared by the preparation method described above.

[0024] In a third aspect, the present invention provides an application of a non-gas-producing lithium-rich lithium iron phosphate cathode material in lithium-ion battery lithium replenishment.

[0025] Compared with existing technologies, the non-gas-generating lithium iron ferrite material provided by this invention uses elemental sulfur or phosphorus at the oxidation active sites to replace oxygen oxidation, achieving lithium replenishment while suppressing oxygen generation, thus solving the problem of lithium iron ferrite in practical applications. The sulfur or phosphorus forms corresponding sulfates or phosphates after oxidation, which does not negatively affect battery cycling. Attached Figure Description

[0026] Figure 1 The cycle performance of the full battery in Embodiment 1 of the present invention;

[0027] Figure 2 The cycle performance of the full battery in Embodiment 2 of the present invention;

[0028] Figure 3 To illustrate the cycle performance of the full battery in Comparison 1 of this invention;

[0029] Figure 4 The cycle performance of the full cell in Comparative Example 2 of this invention;

[0030] Figure 5 The charging curve of the half-cell in Embodiment 3 of the present invention;

[0031] Figure 6 This is the gas production test result of DEMS in Embodiment 3 of the present invention;

[0032] Figure 7The XPS test results for Embodiment 3 of the present invention after full charging;

[0033] Figure 8 The XRD test results before and after charging in Embodiment 3 of the present invention;

[0034] Figure 9 The results of soaking the filtrate obtained after immersing the electrode in Example 3 of the present invention after charging were respectively soaked in an aqueous solution and an acidic solution of BaCl2;

[0035] Figure 10 The charging curve of the half-cell in Comparative Example 3 of this invention;

[0036] Figure 11 The scanning electron microscope image and energy dispersive spectroscopy of the lithium iron phosphate composite material prepared in Example 4 of this invention;

[0037] Figure 12 The image shown is a scanning electron microscope image of the lithium iron phosphate raw material used in Example 4 of this invention.

[0038] Figure 13 The cycle performance of the full cells in Example 4 and Comparative Example 4 of this invention;

[0039] Figure 14 The charge / discharge curves and DEMS curves for Example 5 and Comparative Example 5 are shown.

[0040] Figure 15 Ultrasonic images of the pouch cells in Example 6 and Comparative Example 6 during the first cycle. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0042] In the following embodiments, the composition ratio of the lithium iron phosphate cathode slurry used is lithium iron phosphate: conductive carbon SuperP: binder PVDF (polyvinylidene fluoride) = 8:1:1, NMP (N-methylpyrrolidone) is used as solvent, and the solid content is about 40%.

[0043] Unless otherwise specified, all other raw materials or processing techniques are commercially available materials or conventional processing techniques in the field.

[0044] Example 1:

[0045] A sample obtained by ball milling a mixture of lithium iron phosphate (Li5FeO4), sulfur, and Ketjen black (where the molar ratio of lithium iron phosphate to sulfur is 1:1 and the mass of Ketjen black accounts for 5% of the total mass of the mixture) at 150 r / min for 2 h was heated to 150 °C and held for 2 h. Then, 5% lithium iron phosphate (i.e., 5% of the mass of the positive electrode active material LFP) was added to the lithium iron phosphate positive electrode slurry, resulting in a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.7V at 0.1C, then to 4.3V at 0.01C, and then discharged to 2.5V at a constant current of 0.05C to complete the first cycle. Afterwards, the cells were charged to 3.7V at a constant current and voltage of 0.1C, and then discharged to 2.5V at a constant current of 0.1C for three cycles of activation. Finally, a long-cycle test was conducted at a 0.5C rate, with the long-cycle voltage range being [2.5V, 3.7V].

[0046] Figure 1 This refers to the cycle performance of the full battery in Embodiment 1 of the present invention.

[0047] from Figure 1 It can be seen that in the first 100 cycles of the full battery, there was almost no capacity decay, and the lithium replenishment effect of lithium iron phosphate itself was obtained without causing any adverse effects on the battery.

[0048] Example 2:

[0049] A sample obtained by hand-milling a mixture of lithium iron phosphate, sulfur, and Ketjen black (where the molar ratio of lithium iron phosphate to sulfur is 1:1, and the mass of Ketjen black accounts for 5% of the total mass of the mixture) for 20 minutes was heated to 150℃ and held for 2 hours. Then, 5% lithium iron phosphate was added to the lithium iron phosphate cathode slurry, resulting in a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.7V at 0.1C, then to 4.3V at 0.01C, and then discharged to 2.5V at a constant current of 0.05C to complete the first cycle. Afterwards, the cells were charged to 3.7V at a constant current and voltage of 0.1C, and then discharged to 2.5V at a constant current of 0.1C for three cycles of activation. Finally, a long-cycle test was conducted at a 0.5C rate, with the long-cycle voltage range being [2.5V, 3.7V].

[0050] Figure 2 This refers to the cycle performance of the full battery in Embodiment 2 of the present invention.

[0051] from Figure 2 It can be seen that in the first 300 cycles of the full battery, although the capacity is affected by polarization in the initial few cycles, it gradually recovers to the normal specific capacity in the later cycles, and has a lithium replenishment capacity effect. This is almost consistent with the capacity of ordinary 5% lithium-rich lithium iron phosphate in the first 300 cycles, exhibiting both suppression of gas production and lithium replenishment. It is evident that hand milling leads to less tight bonding between Li5FeO4 and sulfur, resulting in less optimal battery cycle performance compared to ball milling, but it still provides some suppression of gas production and lithium replenishment.

[0052] Comparative Example 1:

[0053] Lithium-rich lithium iron phosphate was directly added to the lithium iron phosphate cathode slurry at a content of 5%, resulting in a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.7V at 0.1C, then to 4.3V at 0.01C, and then discharged to 2.5V at a constant current of 0.05C to complete the first cycle. Afterwards, the cells were charged to 3.7V at a constant current and voltage of 0.1C, and then discharged to 2.5V at a constant current of 0.1C for three cycles of activation. Finally, a long-cycle test was conducted at a 0.5C rate, with the long-cycle voltage range being [2.5V, 3.7V].

[0054] Figure 3 The cycle performance of the full battery in Comparison 1 is presented in this invention.

[0055] from Figure 3 It can be seen that in the first 600 cycles of the full battery cycle, although the lithium replenishment effect is very good in the first 300 cycles, the continuous release of oxygen in the positive electrode due to charging of lithium-rich lithium iron phosphate has a detrimental effect on the cycle performance of the battery, and the capacity decay occurs quickly after 300 cycles.

[0056] Comparative Example 2:

[0057] A lithium iron phosphate cathode slurry was prepared, and a lithium iron phosphate areal capacity of 1.2 mAh / cm³ was obtained. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.7V at 0.1C, then to 4.3V at 0.01C, and then discharged to 2.5V at a constant current of 0.05C to complete the first cycle. Afterwards, the cells were charged to 3.7V at a constant current and voltage of 0.1C, and then discharged to 2.5V at a constant current of 0.1C for three cycles of activation. Finally, a long-cycle test was conducted at a 0.5C rate, with the long-cycle voltage range being [2.5V, 3.7V].

[0058] Figure 4 This is the cycle performance of the full cell in Comparative Example 2 of the present invention.

[0059] from Figure 4 It can be seen that, since ordinary lithium iron phosphate full batteries do not contain lithium-rich lithium iron phosphate as a lithium replenisher, they do not have a lithium replenishment effect. During the 600-cycle process, the capacity decreased uniformly, and since there was no lithium replenisher, it was not negatively affected by the gas production of lithium-rich lithium iron phosphate.

[0060] Example 3:

[0061] A sample obtained by ball milling a mixture of lithium iron ferrite, sulfur, and Ketjen black (where the molar ratio of lithium iron ferrite to sulfur was 1:1 and the mass of Ketjen black accounted for 5% of the total mass) at 150 r / min for 2 h was heated to 150 °C and held for 2 h. Then, a slurry was prepared by mixing the slurry with SP (Super P conductive carbon) and PVDF at a mass ratio of 7:2:1, resulting in an active material loading of 2.8 mg / cm³. 2 The positive electrode was prepared and assembled with a lithium negative electrode in an argon-protected glove box to form a CR2025 button cell. It was charged to 4.5V at a 0.02C rate.

[0062] Figure 5 This is the charging curve of the half-cell in Embodiment 3 of the present invention.

[0063] from Figure 5 It can be seen that most of the capacity of lithium iron phosphate can be released during charging, and it will still have the effect of lithium replenishment.

[0064] Figure 6 This is the gas generation test result of electrochemical differential mass spectrometry (DEMS) in Example 3 of the present invention.

[0065] from Figure 6 It can be seen that almost no oxygen was observed to be generated during the charging process of the treated lithium iron ferrite sample in the DEMS test, thus proving that the method implemented in this invention has a certain inhibitory effect on gas production of lithium iron ferrite.

[0066] Figure 7 The XPS test results for Embodiment 3 of the present invention after charging are shown.

[0067] from Figure 7 It can be seen that after the electrode was charged and tested by XPS, the sulfur in the electrode was found to have turned into a +6 oxidation state, which means that the sulfur element was converted into sulfate. This also proves that the sulfur element replaced the oxygen element in the lithium iron ferrite and underwent an oxidation reaction, thereby inhibiting the production of oxygen to a certain extent.

[0068] Figure 8The XRD test results before and after charging are shown in Embodiment 3 of the present invention.

[0069] from Figure 8 As can be seen, before the electrode was charged, the XRD test clearly detected the peak of lithium iron ferrite (Li5FeO4), while after charging, the peak of lithium iron ferrite disappeared, indicating that the lithium iron ferrite was completely reacted during the charging process.

[0070] Figure 9 The attached figure shows the filtrate obtained after immersing the electrode in Example 3 of this invention after charging, which was then immersed in an aqueous solution and an acidic solution of BaCl2. The figure also shows the precipitate obtained after filtration.

[0071] from Figure 9 It can be seen that the filtrate obtained from soaking showed no obvious phenomenon in water, but after adding the acid solution of BaCl2, a white turbidity quickly appeared, indicating that barium sulfate precipitate was formed. This phenomenon indicates that sulfur reacted with lithium iron ferrite to form sulfate ions, and the precipitate was obtained by filtration.

[0072] Comparative Example 3:

[0073] A slurry was prepared by directly mixing lithium iron ferrite with SP and PVDF in a ratio of 7:2:1, and an active material loading of 2.8 mg / cm³ was obtained. 2 The positive electrode was prepared and assembled with a lithium negative electrode in an argon-protected glove box to form a CR2025 button cell. It was charged to 4.5V at a 0.02C rate.

[0074] Figure 10 This is the charging curve of the half-cell in Comparative Example 3 of the present invention.

[0075] from Figure 10 It can be seen that most of the capacity of lithium iron ferrite can be released during charging, and it will still have the effect of lithium replenishment. However, since the conductivity of lithium iron ferrite itself is not good enough, its capacity is not as good as that of the mixture doped with Ketjen black in Example 3.

[0076] Example 4:

[0077] A mixture of lithium iron phosphate (LiFePO4), phosphorus (P), and Ketjen black (where the molar ratio of LiFePO4 to P is 1:1 and the mass of Ketjen black accounts for 5% of the total mass) was ball-milled at 150 r / min for 2 h. The resulting sample was heated to 450 °C and held for 2 h, then cooled to 280 °C and held for 48 h. This solution was then added at 3 wt% to a lithium iron phosphate cathode slurry, yielding a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.8V at 0.1C, then charged to 4.3V at 0.01C, and then discharged to 2.0V at a constant current of 0.05C to complete the first cycle. After that, the cells were charged to 3.8V at a constant current of 0.1C and discharged to 2.0V at a constant current of 0.1C for three cycles of activation. Then, a long-cycle test was performed at a rate of 0.5C, with the long-cycle voltage range being [2.0V, 3.8V].

[0078] Comparative Example 4:

[0079] A lithium iron phosphate cathode slurry was prepared, and a lithium iron phosphate areal capacity of 1.2 mAh / cm³ was obtained. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode was used to assemble CR2025 button cells in an argon-protected glove box. The cells were first charged to 3.8V at 0.1C, then charged to 4.3V at 0.01C, and then discharged to 2.5V at a constant current of 0.05C to complete the first cycle. After that, the cells were charged to 3.8V at a constant current and constant voltage of 0.1C and discharged to 2.0V at a constant current of 0.1C for two cycles of activation. Then, a long-cycle test was performed at a rate of 0.5C, with the long-cycle voltage range being [2.0V, 3.8V].

[0080] Figure 11 The images shown are scanning electron microscope images and energy dispersive spectroscopy (EDS) spectra of the lithium ferrite-phosphorus composite material prepared in Example 4 of this invention.

[0081] Figure 12 This is a scanning electron microscope image of the lithium iron ferrite raw material used in Example 4 of the present invention.

[0082] from Figure 11 and Figure 12 The comparison shows that the particle size of the lithium iron phosphate composite material is significantly reduced after ball milling, to about 1 to 2 μm, and the lithium iron phosphate, phosphorus and carbon are evenly distributed.

[0083] Figure 13 The cycling performance of the full cells in Example 4 and Comparative Example 4 of this invention is shown.

[0084] from Figure 13 It can be seen that in the first 1000 cycles of the full battery, the full battery in Example 4 exhibits better lithium replenishment performance and cycle stability compared to the full battery in Comparative Example 4, and also improves the coulombic efficiency during the cycle.

[0085] Example 5:

[0086] A sample obtained by ball milling a mixture of lithium-rich lithium iron ferrite, phosphorus (P), and Ketjen black (where the molar ratio of lithium-rich lithium iron ferrite to P is 1:1 and the mass of Ketjen black accounts for 5% of the total mass) at 150 r / min for 2 h was heated to 450 °C and held for 2 h, then cooled to 280 °C and held for 48 h. This mixture was then combined with SP and PVDF in a 7:2:1 ratio to prepare a slurry, yielding an active material loading of 3.6 mg / cm³. 2 The positive electrode was prepared and assembled with a lithium negative electrode in an argon-protected glove box to form a CR2025 button cell. It was charged to 4.5V at a 0.02C rate.

[0087] Comparative Example 5:

[0088] A slurry was prepared by directly mixing lithium iron ferrite with SP and PVDF in a ratio of 7:2:1, and an active material loading of 3.6 mg / cm³ was obtained. 2 The positive electrode was prepared and assembled with a lithium negative electrode in an argon-protected glove box to form a CR2025 button cell. It was charged to 4.5V at a 0.02C rate.

[0089] Figure 14 The charge / discharge curves and DEMS curves for Example 5 and Comparative Example 5 are shown.

[0090] from Figure 14 It can be seen that the gas production during the decomposition process of the lithium iron phosphate composite material is significantly suppressed, and greatly reduced compared to lithium iron phosphate.

[0091] Example 6:

[0092] A mixture of lithium iron phosphate (LiFePO4), phosphorus (P), and Ketjen black (where the molar ratio of LiFePO4 to P is 1:1 and the mass of Ketjen black accounts for 5% of the total mass) was ball-milled at 150 r / min for 2 h. The resulting sample was heated to 450 °C and held for 2 h, then cooled to 280 °C and held for 48 h. This sample was then added at 3% of the final concentration to a lithium iron phosphate cathode slurry, yielding a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2 The graphite anode is used to assemble the pouch cell in a drying room. It is first charged to 3.8V at 0.1C, then charged to 4.3V at 0.01C, and then discharged at a constant current of 0.05C to 2.0V to complete the first cycle.

[0093] Comparative Example 6:

[0094] Lithium-rich lithium iron phosphate was added to the lithium iron phosphate cathode slurry at a content of 3%, resulting in a lithium iron phosphate areal capacity of 1.2 mAh / cm³. 2 The positive electrode sheet, with an area capacity of 1.45 mAh / cm², is simultaneously used. 2The graphite anode is used to assemble the pouch cell in a drying room. It is first charged to 3.8V at 0.1C, then charged to 4.3V at 0.01C, and then discharged at a constant current of 0.05C to 2.0V to complete the first cycle.

[0095] Figure 15 Ultrasonic images of the pouch cells in Example 6 and Comparative Example 6 during the first cycle.

[0096] from Figure 15 It can be seen that the gas production area (blue area) of the pouch battery with added lithium iron phosphate composite material is significantly reduced during the first cycle, while the pouch battery with added lithium iron phosphate exhibits a large amount of gas production during the first cycle, indicating the large-scale application prospects of lithium iron phosphate composite material.

[0097] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a non-gas type lithium-rich lithium iron phosphate anode lithium supplement material, characterized in that, The method comprises the following steps: (1) taking lithium-rich lithium iron phosphate, sulfur or phosphorus, and Ketjen black, grinding them to mix them evenly, and obtaining a mixture; (2) ball-milling the mixture, and then heating and keeping it, so that the sulfur or phosphorus is adsorbed on the Ketjen black and coated on the surface of the lithium-rich lithium iron phosphate, and obtaining a target product; In step (1), the mass ratio of Ketjen black in the mixture is 2-10%; In step (1), the molar ratio of lithium-rich lithium iron phosphate to sulfur or phosphorus is 1:1; In step (2), the ball-milling and heating and keeping processes are carried out in an inert atmosphere, the oxygen concentration is less than 10 ppm, and the water vapor concentration is less than 0.2 ppm; In step (2), when the mixture is composed of lithium-rich lithium iron phosphate, sulfur, and Ketjen black, it is heated to 130-170℃ first, and kept for 1-3 hours; When the mixture is composed of lithium-rich lithium iron phosphate, phosphorus, and Ketjen black, it is heated to 400-500℃ first, and kept for 1-3 hours, and then kept at 200-300℃ for 24-72 hours.

2. The preparation method of the non-gas type lithium-rich lithium iron phosphate anode lithium supplement material according to claim 1, characterized in that, The grinding in step (1) is carried out in a dry atmosphere, and the relative humidity is kept below 10%.

3. The preparation method of the non-gas type lithium-rich lithium iron phosphate anode lithium supplement material according to claim 1, characterized in that, In step (2), during the ball-milling process, the mass ratio of the ball-milling material to the ball-milling beads is 1:(8-12); The rotation speed of the ball-milling is 150-500 rpm, and the time is 2-10 hours.

4. A non-gas type lithium-rich lithium iron phosphate anode lithium supplement material prepared by the method of any one of claims 1-3.

5. The application of the non-gas type lithium-rich lithium iron phosphate anode lithium supplement material of claim 4 in lithium ion battery lithium supplement.

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