Preparation method and application of lithium supplementing material

Abstract

The invention discloses a preparation method and application of a lithium supplementing material, and relates to the technical field of batteries, and the preparation method comprises the following steps: carrying out first ball-milling mixing on a lithium source and a metal source to obtain an initial mixture; adding a first coating agent into the initial mixture, carrying out ball-milling mixing for the second time, then adding a second coating agent, and carrying out ball-milling mixing for the third time to obtain mixed powder; and tabletting, sintering and crushing the mixed powder in an inert protective atmosphere to obtain the lithium supplementing material. Under the synergistic effect of the first coating agent and the second coating agent, the ionic conductivity and the electronic conductivity of the modified lithium supplement material lithium-rich lithium ferrite and lithium-rich lithium nickelate are improved, and the controllable release of active lithium ions is promoted, so that the gram volume exertion of an electrode and the long circulation stability of a battery are promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and in particular to a preparation method and application of a lithium supplementing material. BACKGROUND

[0002] The lithium supplementing material is mainly applied to lithium ion batteries of various systems. By adding these materials in the battery manufacturing process, the lithium consumed when a solid-state electrolyte interface is formed on the negative electrode surface can be effectively made up, thereby reducing irreversible lithium loss, improving the coulomb efficiency and energy density of the battery, and improving the energy density and cycle performance of the battery.

[0003] In some related technologies, the lithium supplementing agent of part of the pole piece material, lithium-rich lithium nickelate, has poor stability in air, unstable structure, and is prone to side reactions with electrolyte at high potential, i.e., metal dissolution at high potential, which leads to a fast release speed of active lithium, affecting the long-term cycle use of the lithium supplementing agent. SUMMARY

[0004] To solve at least one of the problems mentioned in the background, the present application provides a preparation method and application of a lithium supplementing material. Through coating technology, the lithium conduction rate of lithium-rich lithium ironate or lithium-rich lithium nickelate is improved. Under the synergistic action of the first coating agent and the second coating agent, the ion conductivity and electronic conductivity of the modified lithium-rich lithium ironate and lithium-rich lithium nickelate are improved, promoting the controllable release of active lithium ions, thereby promoting the electrode specific capacity and the long cycle stability of the battery, and improving the stability of the lithium supplementing agent in air, the stability of the synthesis process, and the processability of the material.

[0005] The specific technical solutions provided by the embodiments of the present application are as follows:

[0006] In a first aspect, a preparation method of a lithium supplementing material is provided, and the method comprises:

[0007] mixing a lithium source and a metal source by first ball milling to obtain an initial mixture;

[0008] adding a first coating agent to the initial mixture, performing second ball milling, then adding a second coating agent, and performing third ball milling to obtain a mixed powder;

[0009] pressing, sintering, and crushing the mixed powder to obtain the lithium supplementing material.

[0010] In a specific embodiment, the metal source comprises an iron source, and the molar ratio of the lithium source to the iron source is (5:1) to (6:1).

[0011] Alternatively, the metal source comprises a nickel source, and the molar ratio of the lithium source to the nickel source is (2:1) to (3:1).

[0012] In a specific embodiment, the first coating agent accounts for 1wt% to 5wt% of the initial mixture, and the second coating agent accounts for 1wt% to 5wt% of the initial mixture.

[0013] In a specific embodiment, the first coating agent is a sulfur-containing substance; wherein the sulfur-containing substance comprises elemental sulfur.

[0014] In a specific embodiment, the second coating agent is a lithium ion conductor, and the lithium ion conductor comprises one or more of an oxide solid-state electrolyte, a polymer solid-state electrolyte, a halide solid-state electrolyte, or a sulfide solid-state electrolyte.

[0015] Specifically, the oxide solid-state electrolyte comprises one or more of LLZTO, LATP, LLZO, LLTP, LiPON, or LZG;

[0016] And / or, the polymer solid-state electrolyte comprises one or more of PEO, PMMA, PAN, PS, or PVDF;

[0017] And / or, the halide solid-state electrolyte has a chemical formula comprising Li-M1-X electrolyte, wherein M1 in the Li-M1-X electrolyte is one of Sc, Y, La-Lu, Al, Ga, In, Fe, Co, Ni, Ti, Cd, Cr, Mg, Pb, Mn, V, Cu, or Zn; and X is one of F, Cl, Br, or I;

[0018] Alternatively, the halide solid-state electrolyte has a chemical formula comprising Li-M2-X doped electrolyte, and the chemical formula of the Li-M2-X doped electrolyte comprises Li 3-a In 1-a M2 a X6 or Li 3-a M3 1-a M4 a Cl6, the Li 3-a In 1- a M2 a X6, wherein M2 in the Li 3-a M3 1-a M4 a Cl6, wherein M3 is one of Y, Er, or Yb, and M4 is Zr or Hf, and 0

[0019] And / or, the sulfide solid-state electrolyte has a chemical formula comprising (100-x)Li2S 1-x P2S5, (100-x)Li2S1-x SiS2, Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+y S 12 or one or more of Li6PS5CI, wherein 0 < x < 1, 0 < y < 1, and M is one of Go, Sn, or Si.

[0020] Alternatively, the second coating agent is a lithium ion conductor that is a lithium ion conductor intermediate, the lithium ion conductor intermediate comprising one or more of alumina, aluminum hydroxide, or boehmite.

[0021] In one specific embodiment, the iron source comprises one or more of iron chloride, iron nitrate, magnetite, ferrous oxide; in particular, the nickel source comprises one or more of nickel oxide, nickel sulfate, nickel nitrate, or nickel carbonate.

[0022] In one specific embodiment, the lithium source comprises one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium fluoride, lithium chloride, lithium sulfide, or lithium nitride.

[0023] In one specific embodiment, the lithium source and the metal source are first ball-mixed under an inert protective atmosphere, the first ball-mixing being at a speed of 100 rpm to 200 rpm for a time of 2 h to 3 h.

[0024] and / or, the second ball-mixing is performed under an inert protective atmosphere, the second ball-mixing being at a speed of 100 rpm to 200 rpm for a time of 1 h to 2 h;

[0025] and / or, the third ball-mixing is performed under an inert protective atmosphere, the third ball-mixing being at a speed of 100 rpm to 200 rpm for a time of 1 h to 2 h.

[0026] In one specific embodiment, the tabletting of the mixed powder is performed under an inert protective atmosphere, the tabletting being at a pressure of 4 T to 6 T for a dwell time of 1 min to 2 min, the tabletting being to a size of 12 mm to 14 mm.

[0027] and / or, the sintering of the tabletted material is performed under an inert atmosphere, the sintering being at a ramp rate of 2 °C / min to 5 °C / min to a temperature of 700 °C to 900 °C for a dwell time of 1 h to 2 h.

[0028] and / or, said crushing of the sintered material is performed under inert atmosphere protection, and the crushing is performed for 20s / time to 30s / time.

[0029] In a second aspect, the application provides a pole piece, which comprises the lithium supplementing material prepared by the method as described above.

[0030] In a third aspect, the application provides a lithium battery, which comprises the lithium supplementing material prepared by the method as described above or the pole piece as described above.

[0031] The embodiments of the application have the following beneficial effects:

[0032] 1. In the embodiments of the application, two coating agents are used for coating respectively, and the synergistic effect of the first coating agent and the second coating agent improves the ion conductivity and electronic conductivity of the modified lithium supplementing material, such as lithium-rich lithium iron phosphate and lithium-rich lithium nickel phosphate, promotes the controllable release of active lithium ions, thereby promoting the electrode capacity and the long cycle stability of the battery, and improving the stability of the lithium supplementing agent in air, the stability of the synthesis process and the processability of the material.

[0033] 2. After the first coating agent is used for coating by grinding and mixing, the second coating agent is added and ground and mixed for the second coating, wherein the second coating agent is a lithium fast ion conductor or an intermediate compound capable of reacting with a lithium source to generate a lithium fast ion conductor, and the coating of the second coating agent can promote the conduction rate of lithium on the surface of lithium-rich lithium iron phosphate or lithium-rich lithium nickel phosphate.

[0034] 3. The coating of the two coating agents, wherein the first coating agent is a sulfur-containing substance, specifically including but not limited to elemental sulfur, and the addition of the sulfur-containing substance helps to endow the lithium compound with controllable electrochemical activity to achieve controllable release of lithium ions; unlike the traditional pre-lithiation compound which is only effective in the initial cycle, the unique effect of the sulfur-containing substance promotes the controllable release of active lithium ions, which can fully compensate for the irreversible capacity loss in the SEI film formation period, and this mechanism helps to establish a high-quality electrode-electrolyte interface to ensure long-term cycling; compatible with mainstream battery manufacturing processes, ensuring environmental stability and easy integration into the slurry mixing process, and having a chemically stable decomposition product composed of chemically stable solid components, without involving the evolution of any active gas components, such as oxygen, nitrogen and carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 A schematic diagram showing a preparation method of a lithium supplementing material according to the present application is shown.

[0037] Figure 2 A schematic diagram showing a specific preparation process of a lithium supplementing material according to the present application is shown. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] In one embodiment, a preparation method of a lithium supplementing material is provided, as shown in Figure 1 and Figure 2 The method comprises:

[0041] Step 1, a first ball milling mixing of a lithium source and a metal source is performed to obtain an initial mixture.

[0042] The lithium source and the metal source are added into a ball mill tank in a certain proportion, the ball mill tank is sealed, and the mixing is carried out under an inert protective atmosphere. In this embodiment, the inert atmosphere is selected as argon or nitrogen. The reaction is carried out in an inert atmosphere to isolate oxygen in the air, thereby reducing the risk of oxidation of the metal substance. The ball milling speed is 100 rpm to 200 rpm, and the ball milling time is 2 h to 3 h, to obtain an initial mixture. Specifically, the ball milling speed when mixing the lithium source and the metal source is set to one of 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm; the ball milling time when mixing the lithium source and the metal source is set to one of 2 h, 2.5 h or 3 h. Through the above settings, different specific conditions of the ball milling speed and the ball milling time of the lithium source and the metal source in the application can achieve the grinding and mixing of the two.

[0043] It should be noted that the lithium source in this embodiment includes but is not limited to lithium hydroxide, lithium carbonate, lithium oxide, lithium fluoride, lithium chloride, lithium sulfide or lithium nitride. When different types of lithium sources in the above range are achieved, additional lithium sources can be introduced into the electrode material to compensate for the irreversible capacity loss of lithium-ion batteries during formation and subsequent cycling to solve active lithium loss, improve lithium-ion battery energy density and cycle life.

[0044] In a specific embodiment, the metal source is an iron source, wherein the iron source includes but is not limited to iron chloride, iron nitrate, magnetite or ferrous oxide; or the metal source is a nickel source, and the nickel source includes but is not limited to nickel oxide, nickel sulfate, nickel nitrate or nickel carbonate.

[0045] By setting the metal source as an iron source or a nickel source, different types of iron sources or nickel sources in the above range can achieve effective reaction with the lithium source. The iron element in the iron source plays a role in stabilizing the structure and improving the energy density in the battery electrode material. It forms lithium-rich ferrite acid in the reaction process with the lithium source, which is a lithium metal oxide with a very high specific capacity, and the theoretical capacity can reach 867 mAh / g. It can improve the first coulombic efficiency of the negative electrode, and thus improve the capacity, cycle life and energy density of the lithium battery. The nickel element in the nickel source is mainly used to improve the energy density in the battery electrode material. It forms lithium-rich nickel acid in the reaction process with the lithium source, which can also significantly improve the energy density of the battery.

[0046] It should be noted that the molar ratio of the lithium source to the iron source in the embodiment is (5:1) to (6:1), and the specific molar ratio of the lithium source to the iron source includes but is not limited to 5:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1 or 6:1. Through the above setting, the iron source and the lithium source can be prepared into a lithium supplement material meeting the battery performance under the condition of different molar ratios.

[0047] In the embodiment, the molar ratio of the lithium source to the nickel source is (2:1) to (3:1), and the specific molar ratio of the lithium source to the nickel source includes but is not limited to 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3:1. Through the above setting, the nickel source and the lithium source can be prepared into a lithium supplement material meeting the battery performance under the condition of different molar ratios.

[0048] Step 2, adding a first coating agent to the initial mixture, performing second ball milling mixing, then adding a second coating agent, and performing third ball milling mixing to obtain a mixed powder.

[0049] Specifically, after adding the first coating agent to the initial mixture, the second ball milling mixing is performed under an inert protective atmosphere. Specifically, the inert atmosphere is configured as argon or nitrogen, the ball milling tank is sealed, the rotation speed of the second ball milling is 100 rpm to 200 rpm, and the second ball milling time is 1 h to 2 h. Then, the second coating agent is added, and the third ball milling mixing is performed under an inert protective atmosphere. Specifically, the inert atmosphere is configured as argon or nitrogen, the ball milling tank is sealed, the rotation speed of the third ball milling is 100 rpm to 200 rpm, and the third ball milling time is 1 h to 2 h. The mixed slurry is obtained and dried to obtain the mixed powder.

[0050] In the embodiment, the rotation speed of the second ball milling is set to one of 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm, and the time of the second ball milling is set to one of 1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h. Through the above setting, the coating process of the first coating agent can be completed after the first coating agent is added and the second ball milling mixing is performed under different specific conditions within the range of the ball milling rotation speed and the ball milling time.

[0051] Further, the rotation speed of the third ball milling is set to one of 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm; the time of the third ball milling is set to one of 1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h. Through the above settings, the third ball milling mixing after the second coating agent is added under the inert atmosphere is realized, and through setting the ball milling speed and the ball milling time in the above range, the coating of the second coating agent can be realized under different specific conditions, and the mixed powder is obtained after drying.

[0052] In the embodiment, the mass percentage of the first coating agent in the initial mixture in the lithium supplementing material is 1wt%-5wt%, and the specific mass percentage of the first coating agent includes but is not limited to 1wt%, 1.2wt%, 1.4wt%, 1.5wt%, 2wt%, 2.5wt%, 2.7wt%, 2.9wt%, 3wt%, 3.2wt%, 3.4wt%, 3.5wt%, 4wt%, 4.2wt%, 4.4wt%, 4.5wt%, 4.7wt%, 4.9wt% or 5wt%. Through the above settings, the first coating agent can realize the coating process after grinding under the above adding amount in the above mass percentage range.

[0053] It should be noted that the first coating agent in the embodiment is a sulfur-containing substance, and especially elemental sulfur can give the lithium-rich compound controllable electrochemical activity; unlike the traditional pre-lithiated compound which only plays a role in the initial cycle, the sulfur-containing substance promotes the controllable release of active lithium ions to fully compensate for the irreversible capacity loss in the SEI film formation period. At the same time, the presence of the first coating agent helps to establish a high-quality electrode-electrolyte interface to ensure sustained long-term cycling; the coating process of the first coating agent is compatible with mainstream battery manufacturing processes, ensuring environmental stability and easy integration into the slurry mixing process, and the first coating agent and the decomposition products in the coating process have chemical stable decomposition products which are composed of chemically stable solid components and do not involve the evolution of any active gas components.

[0054] In the embodiment, the second coating agent in the lithium supplementing material accounts for 1wt%-5wt% of the mass percentage of the initial mixture. Specifically, the mass percentage of the second coating agent in the initial mixture includes but is not limited to 1wt%, 1.2wt%, 1.4wt%, 1.5wt%, 2wt%, 2.5wt%, 2.7wt%, 2.9wt%, 3wt%, 3.2wt%, 3.4wt%, 3.5wt%, 4wt%, 4.2wt%, 4.4wt%, 4.5wt%, 4.7wt%, 4.9wt% or 5wt%. Through the above setting, the second coating agent can realize the coating process after the second grinding in the above mass percentage range, and the coating of the second coating agent can promote the conduction rate of the lithium on the surface of the lithium-rich lithium iron phosphate or lithium-rich lithium nickelate.

[0055] It should be noted that the second coating agent in the embodiment is configured as a lithium ion conductor, which includes but is not limited to an oxide solid-state electrolyte, a polymer solid-state electrolyte, a halide solid-state electrolyte or a sulfide solid-state electrolyte.

[0056] In a specific embodiment, the oxide solid-state electrolyte includes but is not limited to LLZTO, LATP, LLZO, LLTP, LiPON or LZG; and / or, the polymer solid-state electrolyte includes but is not limited to PEO, PMMA, PAN, PS or PVDF.

[0057] And / or, the chemical general formula of the halide solid-state electrolyte includes a Li-M1-X system electrolyte, M1 in the Li-M1-X system electrolyte is one of Sc, Y, La-Lu, Al, Ga, In, Fe, Co, Ni, Ti, Cd, Cr, Mg, Pb, Mn, V, Cu or Zn, and X is one of F, Cl, Br or I;

[0058] Alternatively, the halide solid-state electrolyte includes a Li-M2-X doped electrolyte, the chemical general formula of the Li-M2-X doped electrolyte includes Li 3-a In 1-a M2 a X6 or Li 3-a M3 1-a M4 a Cl6, Li 3-a In 1-a M2 a X6, M2 in X6 is Zr or Sc, and X is F or Cl; Li 3-a M3 1-a M4 a Cl6, M3 in Cl6 is one of Y, Er or Yb, and M4 is Zr or Hf, wherein 0

[0059] and / or, the chemical formula of the sulfide solid-state electrolyte includes (100-x)Li2S 1-x P2S5, (100-x)Li2S 1- x SiS2, Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+y S 12 or one of Li6PS5Cl, wherein 0

[0060] In one specific embodiment, alternatively, the second coating agent is configured as a lithium ion conductor intermediate, and the lithium ion conductor intermediate includes, but is not limited to, aluminum oxide, aluminum hydroxide or boehmite.

[0061] It should be noted that in the present application, the second coating agent is selected as a lithium ion conductor or a lithium ion conductor intermediate, wherein the lithium ion conductor is a lithium fast ion conductor, and the lithium ion conductor intermediate is a compound capable of reacting with a lithium source to form a lithium fast ion conductor. Moreover, the second coating agent and the first coating agent play a synergistic role, which can improve the ion conductivity and electronic conductivity of the modified lithium-rich lithium iron phosphate and lithium-rich lithium nickelate, promote the controllable release of active lithium ions, thereby promoting the capacity of the electrode and the long-term cycle stability of the battery, improving the stability of the lithium supplement agent in air, thereby improving the stability of the synthesis process and the processability of the material.

[0062] Step 3, the mixed powder is pressed, sintered and crushed to obtain a lithium supplement material.

[0063] In the present embodiment, specifically, the mixed powder is pressed under an inert protective atmosphere, wherein the inert atmosphere is configured as argon or nitrogen. The pressed material is transferred to a muffle furnace, and the pressed material is sintered under an inert gas protective atmosphere, wherein the inert atmosphere is configured as argon or nitrogen. The sintered material is transferred to a crusher for crushing to obtain a lithium supplement material.

[0064] In one specific embodiment, the pressure for tabletting the mixed powder is 4T-6T, the pressure holding time is 1min-2min, and the tablet size is 12mm-14mm. Specifically, the pressure for tabletting is set to be one of 4T, 4.1T, 4.2T, 4.3T, 4.4T, 4.5T, 4.6T, 4.7T, 4.8T, 4.9T, 5T, 5.1T, 5.2T, 5.3T, 5.4T, 5.5T, 5.6T, 5.7T, 5.8T, 5.9T or 6T; the pressure holding time for tabletting is set to be one of 1min, 1.5min or 2min; and the size of the tablet is set to be one of 12mm, 13mm or 14mm. Through the above settings, the tabletting of the material can be achieved when the pressure for tabletting, the pressure holding time for tabletting and the size of the tablet are set to be different conditions within the above pressure range.

[0065] Further, the tabletted material is transferred to a muffle furnace, the muffle furnace is sealed and started to run, and sintering is performed under an inert gas protection atmosphere, wherein the inert gas atmosphere is configured to be argon or nitrogen, the heating rate is set to be 2℃ / min-5℃ / min, the sintering temperature is 700℃-900℃, and the holding time is 1h-2h.

[0066] Specifically, the tabletted material is sintered in the muffle furnace, the heating rate for sintering is set to be one of 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min or 5℃ / min; the sintering temperature is set to be one of 700℃, 720℃, 740℃, 760℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃; and the holding time is set to be one of 1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h. Through the above settings, the sintering process of the tabletted material can be completed when different sintering temperature and heating rate conditions and holding time are selected.

[0067] Further, the sintered material is transferred to a crusher for crushing, the crushing condition is 20s / time-30s / time, and the crushing is continuously performed until the powder is uniformly refined, so that the lithium supplement material is obtained.

[0068] Specifically, the crushing condition is set to be one of 20s / time, 21s / time, 22s / time, 23s / time, 24s / time, 25s / time, 26s / time, 27s / time, 28s / time, 29s / time or 30s / time. Through the above settings, the crushing of the material can be achieved to obtain the lithium supplement material when different parameter values in the above crushing conditions are selected.

[0069] By the scheme in this embodiment, two coating agents are used for coating respectively, wherein the first coating agent is set as a sulfur-containing substance, specifically including but not limited to elemental sulfur, and the addition of the sulfur-containing substance helps to endow the lithium compound with controllable electrochemical activity, so as to realize the controllable release of lithium ions; unlike the traditional pre-lithiated compound which is only effective in the initial cycle, the unique effect of the sulfur-containing substance promotes the controllable release of active lithium ions, which can fully compensate for the irreversible capacity loss in the SEI film formation period, and this mechanism helps to establish a high-quality electrode-electrolyte interface, ensuring the long-term cycle; compatible with mainstream battery manufacturing processes, ensuring environmental stability and easy integration into the slurry mixing process, and having chemical stable decomposition products composed of chemically stable solid components, without involving the evolution of any active gas components such as oxygen, nitrogen and carbon dioxide.

[0070] Moreover, through the synergistic effect of the first coating agent and the second coating agent, the ion conductivity and electronic conductivity of the modified lithium-rich lithium iron phosphate and lithium-rich lithium nickel phosphate are improved, which promotes the controllable release of active lithium ions, thereby promoting the electrode capacity and long cycle stability of the battery, while improving the stability of the lithium supplement agent in air and the stability of the synthesis process and the processability of the material.

[0071] In one embodiment, the present application provides an electrode sheet, which comprises the lithium supplement material prepared by the above-mentioned preparation method of lithium supplement material.

[0072] In one embodiment, the present application provides a lithium battery comprising the lithium supplement material prepared by the above-mentioned preparation method of lithium supplement material or the above-mentioned electrode sheet.

[0073] Embodiment 1

[0074] Corresponding to the above-mentioned embodiment, a preparation method of lithium supplement material is provided, which specifically comprises the following steps:

[0075] S1, lithium hydroxide and ferric oxide are put into a ball mill jar according to a molar ratio of 5:1, and after being sealed, low-speed ball milling is performed, the ball milling speed is 200 rpm, the ball milling time is 1 h, and nitrogen is set as an inert atmosphere for protection.

[0076] S2, 2wt% of elemental sulfur is added to the above-mentioned initial mixture for low-speed ball milling, the ball milling speed is 150 rpm, the ball milling time is 1 h, and nitrogen is set as an inert atmosphere for protection.

[0077] S3, add 2wt% of oxide solid-state electrolyte LATP to the mixture in step S2 above, and mix by low-speed ball milling, the ball milling speed is 150 rpm, the ball milling time is 1 h, and nitrogen is set as the inert atmosphere for protection, to obtain a mixed powder.

[0078] S4, transfer the mixed powder above to a tablet press for tabletting, the pressure is 4T, the pressure maintaining time is 1 min, the tablet size is 14 mm, and nitrogen is set as the inert atmosphere for protection.

[0079] S5, transfer the tabletting material above to a muffle furnace for sintering, the heating rate is 2℃ / min, the sintering temperature is 700℃, the holding time is 2 h, and nitrogen is set as the inert atmosphere for protection.

[0080] S6, finally, transfer the sintered material above to a crusher for crushing, 30s / time, so that the powder is uniformly refined, and the lithium supplement material is obtained, the lithium supplement material prepared in this embodiment is a modified lithium-rich lithium iron phosphate lithium supplement material.

[0081] Example 2

[0082] Corresponding to the above embodiment, this embodiment provides a preparation method of a lithium supplement material, which is different from example 1 in that the mass percentage of the first coating agent elemental sulfur is configured to be 0.5wt%, and other preparation conditions are the same as in example 1, to obtain a lithium supplement material.

[0083] Example 3

[0084] Corresponding to the above embodiment, this embodiment provides a preparation method of a lithium supplement material, which is different from example 1 in that the mass percentage of the first coating agent elemental sulfur is configured to be 1wt%, and other preparation conditions are the same as in example 1, to obtain a lithium supplement material.

[0085] Example 4

[0086] Corresponding to the above embodiment, this embodiment provides a preparation method of a lithium supplement material, which is different from example 1 in that the mass percentage of the first coating agent elemental sulfur is configured to be 4wt%, and other preparation conditions are the same as in example 1, to obtain a lithium supplement material.

[0087] Example 5

[0088] Corresponding to the above embodiment, this embodiment provides a preparation method of a lithium supplement material, which is different from example 1 in that the mass percentage of the first coating agent elemental sulfur is configured to be 5wt%, and other preparation conditions are the same as in example 1, to obtain a lithium supplement material.

[0089] Example 6

[0090] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from embodiment 1 in that the mass percentage of the first coating agent elemental sulfur is configured to be 6wt%, and other preparation conditions are the same as in embodiment 1, so as to obtain the lithium supplementing material.

[0091] Embodiment 7

[0092] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which specifically comprises the following steps:

[0093] S1, lithium oxide and iron oxide are put into a ball mill jar at a molar ratio of 5:1, and after being sealed, low-speed ball milling is performed, the ball milling speed is 200 rpm, the ball milling time is 1h, nitrogen gas is set as an inert atmosphere for protection, and an initial mixture is obtained.

[0094] S2, 3wt% elemental sulfur is taken and added to the above initial mixture for low-speed ball milling, the ball milling speed is 150 rpm, the ball milling time is 1h, and nitrogen gas is set as an inert atmosphere for protection.

[0095] S3, 3wt% of oxide solid-state electrolyte LLZO is taken and added to the mixture of S2 for low-speed ball milling, the ball milling speed is 150 rpm, the ball milling time is 1h, and nitrogen gas is set as an inert atmosphere for protection, to obtain a mixed powder.

[0096] S4, the above mixed powder is transferred to a tablet press for tabletting, the pressure is 4T, the pressure holding time is 1min, the tablet size is 14mm, and nitrogen gas is set as an inert atmosphere for protection.

[0097] S5, the above tablet material is transferred to a muffle furnace for sintering, the heating rate is 2℃ / min, the sintering temperature is 800℃, the holding time is 2h, and nitrogen gas is set as an inert atmosphere for protection.

[0098] S6, finally, the above sintered material is transferred to a crusher for crushing, 30s / time, so that the powder is uniformly refined, and the lithium supplementing material is obtained.

[0099] Embodiment 8

[0100] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from embodiment 7 in that the mass percentage of the second coating agent oxide solid-state electrolyte LLZO is configured to be 0.5wt%, and other preparation conditions are the same as in embodiment 7, so as to obtain the lithium supplementing material.

[0101] Embodiment 9

[0102] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from that of embodiment 7 in that the mass percentage of the second coating agent oxide solid-state electrolyte LLZO is 1wt%, and other preparation conditions are the same as those in embodiment 7, so as to obtain the lithium supplementing material.

[0103] Embodiment 10

[0104] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from that of embodiment 7 in that the mass percentage of the second coating agent oxide solid-state electrolyte LLZO is 4wt%, and other preparation conditions are the same as those in embodiment 7, so as to obtain the lithium supplementing material.

[0105] Embodiment 11

[0106] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from that of embodiment 7 in that the mass percentage of the second coating agent oxide solid-state electrolyte LLZO is 5wt%, and other preparation conditions are the same as those in embodiment 7, so as to obtain the lithium supplementing material.

[0107] Embodiment 12

[0108] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which is different from that of embodiment 7 in that the mass percentage of the second coating agent oxide solid-state electrolyte LLZO is 6.5wt%, and other preparation conditions are the same as those in embodiment 7, so as to obtain the lithium supplementing material.

[0109] Embodiment 13

[0110] Corresponding to the above embodiment, the present embodiment provides a preparation method of a lithium supplementing material, which specifically comprises the following steps:

[0111] S1, lithium oxide and nickel oxide are put into a ball mill jar according to a molar ratio of 2:1, and after being sealed, low-speed ball milling is performed, the ball milling speed is 200rpm, the ball milling time is 1h, and nitrogen is used as an inert atmosphere for protection, to obtain an initial mixture.

[0112] S2, 3wt% elemental sulfur is taken and added to the above initial mixture for low-speed ball milling, the ball milling speed is 150rpm, the ball milling time is 1h, and nitrogen is used as an inert atmosphere for protection.

[0113] S3, 5wt% halide solid-state electrolyte Li3InCl6 is taken and added to the mixture in S2 for low-speed ball milling, the ball milling speed is 150rpm, the ball milling time is 1h, and nitrogen is used as an inert atmosphere for protection, to obtain a mixed powder.

[0114] S4, transfer the mixed powder above to a tablet press to press the tablet, the pressure is 5T, the pressure maintaining time is 1 min, the tablet size is 12mm, nitrogen is used as inert atmosphere for protection.

[0115] S5, transfer the tablet material above to a muffle furnace to sinter, the heating rate is 2℃ / min, the sintering temperature is 800℃, the holding time is 2h, nitrogen is used as inert atmosphere for protection.

[0116] S6, finally, transfer the sintered material above to a crusher to crush, 40s / time, so that the powder is uniformly refined, and the lithium supplement material is obtained, the lithium supplement material prepared in this embodiment is a modified lithium-rich lithium nickelate type lithium supplement material.

[0117] Example 14

[0118] The lithium supplement material prepared in Examples 1-6 is added to the positive electrode material, and the following steps are used to prepare the button cell, and the electrode sheet without adding the lithium supplement material is assembled into the button cell in Comparative Example 1, and the button cells prepared above are tested respectively. Specifically, the steps of preparing the button cell using the lithium supplement material prepared in Examples 1-6 are as follows:

[0119] S1, lithium iron phosphate, lithium supplement material, conductive carbon SP, and binder PVDF are weighed according to the mass ratio of 95:1:2:2, the solvent is NMP, the slurry is uniformly coated on the Al current collector to obtain an LFP electrode sheet, which is used as the positive electrode of the battery;

[0120] S2, the coated electrode sheet is dried in an oven at 90℃ to remove the water in the slurry;

[0121] S3, the electrode sheet obtained in S2 is rolled to obtain a compacted electrode sheet, and the electrode sheet is compacted to 2.6g / cm 3 ;

[0122] S4, the electrode sheet obtained in S3 is further vacuum dried in an oven at 140℃ to remove excess water;

[0123] S5, the electrode sheet in S4 is cut and assembled with a graphite negative electrode to form a button cell, and the electrolyte uses 1M LiPF6 in EC:DEC=1:1.

[0124] The button cells prepared above are tested under the same environment and conditions, and the test results are shown in Table 1.

[0125] Table 1 First test results of button cells

[0126]

[0127] From the data in Table 1, it can be concluded that the first cycle charging capacity, the first cycle discharging capacity and the 50th cycle discharging capacity of the battery added with the lithium supplementing material prepared in this embodiment are all higher than those of the battery without the lithium supplementing material prepared in this embodiment, and the 50th cycle discharging capacity of the button cell added with the lithium supplementing material prepared in this embodiment reaches 145.2 mAh g -1 Therefore, it is illustrated that the lithium supplementing material prepared in this embodiment improves the ion conductivity and electronic conductivity of the modified lithium-rich lithium ferrite and lithium-rich lithium nickelate, promotes the controllable release of active lithium ions, and thus promotes the electrode specific capacity and the long cycle stability of the battery.

[0128] Further, in combination with the test data in Embodiments 1-6, it can also be concluded that when the second coating agent is controlled to be unchanged and only the first coating agent is set to different amounts, it can be seen that when the amount of the first coating agent is in the range of 1wt%-5wt%, the charge-discharge performance of the battery corresponding to the lithium supplementing material is better, and when the amount of the first coating agent is 4wt%, the lithium supplementing material prepared in this embodiment improves the conductivity of the battery to a higher level and makes the prepared battery have better stability; and when the amount of the first coating agent is not in the above range, although the lithium supplementing material in this embodiment is added, the charge-discharge performance of the prepared battery is significantly decreased, and the 50th cycle discharging capacity is also decreased to a lower level of about 100 mAh g -1 , thereby verifying that the addition of the lithium supplementing material of the present application promotes the controllable release of active lithium ions, makes the electrode specific capacity and the long cycle stability of the battery.

[0129] Embodiment 15

[0130] The lithium supplementing material prepared in Embodiments 7-12 is added to the positive electrode material, and the following steps are used to prepare a button cell, and a button cell is assembled by using an LFP electrode sheet without adding a lithium supplementing material and a graphite negative electrode as Comparative Example 2, and the above button cells are tested respectively. Specifically, the steps for preparing a button cell using the lithium supplementing material prepared in Embodiments 7-12 are as follows:

[0131] S1, lithium iron phosphate, lithium supplementing material, conductive carbon SP, and binder PVDF are proportioned according to a mass ratio of 95:1:2:2, the solvent is NMP, the slurry is uniformly coated on an Al current collector to obtain an LFP electrode sheet as a battery positive electrode;

[0132] S2, the coated electrode sheet is dried in an oven at 90°C to remove the water in the slurry;

[0133] S3, the electrode sheet obtained in S2 is rolled to obtain a compacted electrode sheet, and the compacted electrode sheet is 2.6 g / cm 3 ;

[0134] S4, the polar sheet obtained in S3 is further vacuum dried in an oven at 140°C to remove excess moisture;

[0135] S5, the polar sheet in S4 is cut and assembled with a graphite negative electrode to form a button cell, and the electrolyte uses 1M LiPF6 in EC:DEC = 1:1.

[0136] The button cell prepared above is tested under the same environment and conditions, and the test results are shown in Table 2.

[0137] Table 1 Second test results of button cell

[0138]

[0139]

[0140] From the data in Table 2, it can be concluded that the first charge capacity, the first discharge capacity and the 50th cycle discharge capacity of the battery added with the lithium supplementing material prepared in the scheme of the present embodiment are all higher than those of the battery without the lithium supplementing material prepared in the scheme of the present embodiment, and the 50th cycle discharge capacity of the third button cell added with the lithium supplementing material prepared in the scheme of the present embodiment reaches 148.9 mAh g -1 , which further illustrates that the lithium supplementing material prepared in the present embodiment improves the ion conductivity and electronic conductivity of the modified lithium-rich lithium ferrite and lithium-rich lithium nickelate, promotes the controllable release of active lithium ions, and thus promotes the capacity of the electrode and the long cycle stability of the battery.

[0141] Further, combining the data in Table 2, it can be concluded that when the first coating agent is controlled not to change and only the second coating agent is set to different amounts, it can be seen that when the amount of the second coating agent is in the range of 1wt%~5wt%, the charge-discharge performance of the battery corresponding to the lithium supplementing material is better, and when the second coating agent is not in the above range, the charge-discharge performance of the corresponding battery decreases significantly; which verifies that the addition of the lithium supplementing material of the present application promotes the controllable release of active lithium ions, so that the capacity of the electrode and the long cycle stability of the battery are improved.

[0142] Although the preferred embodiments in the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0143] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for preparing a lithium supplement material, characterized in that, The method comprises: carrying out first ball-milling mixing of a lithium source and a metal source to obtain an initial mixture; adding a first coating agent to the initial mixture, carrying out second ball-milling mixing, then adding a second coating agent, and carrying out third ball-milling mixing to obtain a mixed powder; carrying out tabletting, sintering and crushing on the mixed powder to obtain a lithium supplement material. 2.The method for preparing a lithium supplement material according to claim 1, characterized in that, The metal source comprises an iron source or a nickel source, and the molar ratio of the lithium source to the iron source is (5:1) to (6:1); Alternatively, the metal source comprises a nickel source, and the molar ratio of the lithium source to the nickel source is (2:1) to (3:1).

3. The method for preparing a lithium supplement material according to claim 1 or 2, characterized in that, The first coating agent accounts for 1wt% to 5wt% of the mass percentage of the initial mixture, and the second coating agent accounts for 1wt% to 5wt% of the mass percentage of the initial mixture.

4. The method for preparing a lithium supplement material according to claim 1 or 2, characterized in that, The first coating agent is a sulfur-containing substance, and the sulfur-containing substance comprises elemental sulfur. 5.The method for preparing a lithium supplement material according to claim 4, characterized in that, The second coating agent is a lithium ion conductor, and the lithium ion conductor comprises one or more of an oxide solid-state electrolyte, a polymer solid-state electrolyte, a halide solid-state electrolyte or a sulfide solid-state electrolyte; Alternatively, the second coating agent is a lithium ion conductor intermediate, and the lithium ion conductor intermediate comprises one or more of alumina, aluminum hydroxide or boehmite. 6.The method for preparing a lithium supplement material according to claim 5, characterized in that, The oxide solid-state electrolyte comprises one or more of LLZTO, LATP, LLZO, LLTP, LiPON or LZG; And / or, the polymer solid-state electrolyte comprises one or more of PEO, PMMA, PAN, PS or PVDF; And / or, the chemical general formula of the halide solid-state electrolyte comprises a Li-M1-X system electrolyte, M1 in the Li-M1-X system electrolyte is one of Sc, Y, La-Lu, Al, Ga, In, Fe, Co, Ni, Ti, Cd, Cr, Mg, Pb, Mn, V, Cu or Zn, and X is one of F, Cl, Br or I; Alternatively, the halide solid-state electrolyte comprises a Li-M2-X system doped electrolyte, a chemical general formula of the Li-M2-X system doped electrolyte comprises Li 3-a In 1-a M2 a X6, wherein M2 is Zr or Sc, and X is F or Cl; the Li 3-a M3 1-a M4 a Cl6, wherein M3 is one of Y, Er or Yb, and M4 is Zr or Hf, and 0 < a < 1. 3-a In 1-a M2 a X6, wherein M2 is Zr or Sc, and X is F or Cl; the Li 3-a M3 1-a M4 a Cl6, wherein M3 is one of Y, Er or Yb, and M4 is Zr or Hf, and 0 < a < 1. and / or the chemical formula of the sulfide solid-state electrolyte comprises (100-x)Li2S 1-x P2S5, (100-x)Li2S 1- x SiS2, Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+y S 12 or one of Li6PS5Cl, wherein 0 0 7. The method of producing a lithium supplement material according to claim 1 or 2, wherein The method further comprises: The lithium source and the metal source are subjected to the first ball-milling mixing under an inert protective atmosphere, the rotation speed of the first ball-milling is 100rpm to 200rpm, and the time of the first ball-milling is 2h to 3h; And / or, the second ball-milling mixing is carried out under an inert protective atmosphere, the rotation speed of the second ball-milling is 100rpm to 200rpm, and the time of the second ball-milling is 1h to 2h; And / or, the third ball-milling mixing is carried out under an inert protective atmosphere, the rotation speed of the third ball-milling is 100rpm to 200rpm, and the time of the third ball-milling is 1h to 2h.

8. The method of producing a lithium supplement material according to claim 1 or 2, wherein The tabletting of the mixed powder is carried out under an inert protective atmosphere, the pressure of the tabletting is 4T to 6T, the pressure holding time of the tabletting is 1min to 2min, and the size of the tabletting is 12mm to 14mm; And / or, the sintering of the tabletted material is carried out under an inert protective atmosphere, the temperature rising rate of the sintering is 2℃ / min to 5℃ / min, the temperature of the sintering is 700℃ to 900℃, and the holding time of the sintering is 1h to 2h; And / or, the crushing is performed on the sintered material under an inert protective atmosphere, and the crushing is performed for 20-30 seconds per time.

9. A pole piece characterized by, The pole piece comprises a lithium supplementing material prepared by the preparation method of the lithium supplementing material in any one of claims 1-8.

10. A lithium battery, characterized by, The lithium battery comprises the lithium supplementing material prepared by the preparation method of the lithium supplementing material in any one of claims 1-8 or the pole piece in claim 9.

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