Quick-filling type ternary precursor material as well as preparation method and application thereof

Abstract

The invention discloses a fast-filling type ternary precursor material and a preparation method and application thereof, the precursor material is spherical or sphere-like particles, the chemical formula of the precursor material is NixCoyMnz (OH) 2 or NixCoyMnzCO3, x is more than or equal to 0.1 and less than or equal to 0.8, y is more than or equal to 0.1 and less than or equal to 0.3, z is more than or equal to 0.1 and less than or equal to 0.8, and x + y + z = 1; the nitrogen element content in the precursor material is distributed at each part of the material in a gradient concentration manner from low to high from inside to outside, the core represents the precursor material when the particle size D50 reaches 50% of the target D50, the nitrogen content of the core is 0.11-0.52 wt%, and the nitrogen content of the shell is 0.61-1.92 wt%. The ternary precursor material and the lithium source are mixed and sintered to form the positive electrode material, so that the positive electrode material has a core-shell structure with a compact inner part and a low specific surface and a loose outer part and a high specific surface, and the structure has good resistance to stress deformation generated by high-voltage charging and discharging; meanwhile, the loose shell structure with the high specific surface area is beneficial for increasing the wettability of the material and an electrolyte and lithium battery active sites, so that the fast charging performance and the cycling stability of the material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a fast-charging ternary precursor material and a preparation method and application thereof. Background Art

[0002] At present, the charging time of electric vehicles is long, and the experience is poor compared to gasoline vehicles, which seriously affects the development and promotion of electric vehicles. At present, many car companies have adopted solutions such as battery replacement and fast charging to solve this problem. Battery replacement has high investment costs and non-standard technology, making it difficult to popularize widely; fast charging mainly has two directions: high current and high voltage. High current technology is easier to transform and is compatible with existing charging equipment, but there is a serious problem of heat loss; high voltage technology has the advantages of low heat loss and increased cruising range, and is the main development trend. For high-voltage fast charging, in addition to developing supporting hardware facilities such as high-voltage charging piles, the research and development of electrode materials suitable for high-voltage charging and discharging is also a trend in material development. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a fast-charging ternary precursor material and a preparation method and application thereof.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme: a fast-charging ternary precursor material, the precursor material is spherical or quasi-spherical particles, and its material chemical formula is Ni x Co y Mn z (OH)2 or Ni x Co y Mn z CO3, wherein 0.1≤x≤0.8, 0.1≤y≤0.3, 0.1≤z≤0.8, x+y+z=1; the nitrogen content in the precursor material is distributed in various parts of the material in a gradient concentration from low to high from the inside to the outside, the inner core represents the precursor material when the particle size D50 reaches 50% of the target D50, the inner core nitrogen content is 0.11-0.52wt%, and the outer shell nitrogen content is 0.61-1.92wt%.

[0005] A method for preparing a fast-charging ternary precursor material comprises the following steps:

[0006] (1) mixing a nickel source, a cobalt source, and a manganese source to obtain a mixed metal salt solution;

[0007] (2) mixing a mixed metal salt solution, a low concentration silk fibroin aqueous solution, ammonia water and alkaline solution, and performing a coprecipitation reaction under an inert atmosphere, and pausing the reaction when the particle size D50 of the reaction reaches 50% of the target D50, thereby obtaining a nitrogen-doped ternary precursor core;

[0008] (3) The low-concentration silk fibroin aqueous solution is replaced with a high-concentration silk fibroin aqueous solution and the reaction is continued. The reaction is stopped after the target D50 is reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0009] As a further description of the above technical solution:

[0010] In the step (1), the molar concentration of nickel in the mixed metal salt solution is 0.05-2.4 mol / L, the molar concentration of cobalt is 0.05-0.9 mol / L, the molar concentration of manganese is 0.05-2.4 mol / L, and the total molar concentration of nickel, cobalt and manganese is 0.5-3.0 mol / L.

[0011] As a further description of the above technical solution:

[0012] In the step (2), the concentration of the low-concentration silk fibroin aqueous solution is 0.3-1.5 wt %; in the step (3), the concentration of the high-concentration silk fibroin aqueous solution is 2.0-6.0 wt %.

[0013] As a further description of the above technical solution:

[0014] In the steps (2) and (3), the pH of the coprecipitation reaction is 9 to 14, and the concentration of the ammonia water is 0.1 to 1.0 mol / L.

[0015] As a further description of the above technical solution:

[0016] The nickel source includes any one or more of nickel chloride, nickel nitrate, nickel sulfate, and nickel acetate; the cobalt source includes any one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate; the manganese source includes any one or more of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate; the alkali solution includes any one of sodium carbonate solution, sodium bicarbonate solution, and sodium hydroxide.

[0017] A fast-charging ternary positive electrode material is prepared by mixing a lithium source and the fast-charging ternary precursor material and then sintering them.

[0018] A fast-charging lithium-ion battery, wherein the positive electrode plate of the fast-charging lithium-ion battery comprises the fast-charging ternary positive electrode material.

[0019] The present invention has the following beneficial effects:

[0020] 1. Compared with the prior art, the present invention proposes to use silk fibroin to carry out nitrogen doping reaction of precursor, and at the same time, nitrogen element is distributed in various parts of the material in a gradient concentration from low to high from the inside to the outside. After the subsequent ternary precursor is mixed with the lithium source and sintered, the nitrogen element in the inner core is in situ doped into the positive electrode material. Due to its small content and low gas production, it will not damage the internal structure of the material. More nitrogen elements will be retained in the outer shell due to the use of high-concentration silk fibroin aqueous solution, while carbon, oxygen and other substances will leave more pores while being consumed during sintering, so that the positive electrode material presents a core-shell structure of compact low specific surface area inside and loose high specific surface area outside. This structure has good resistance to stress deformation caused by high-voltage charging and discharging. At the same time, the loose high specific surface area shell structure helps to increase the wettability of the material with the electrolyte and the lithium battery active sites, thereby improving the fast charging performance and cycle stability of the material.

[0021] 2. Compared with the prior art, the nitrogen atoms in the present invention replace a part of the oxygen atoms in the positive electrode material. The atomic radius of the nitrogen atoms is wider than that of the oxygen atoms, which can better open the transmission channel for lithium ions, improve the lithium ion mobility of the material under large current, improve the cycle stability and rate performance of the positive electrode material, and improve the charging efficiency of the battery.

[0022] 3. Compared with the prior art, the present invention has a pair of lone pairs of electrons on the outside of the nitrogen atom, and has a stronger binding force with the metal atom. The in-situ doping of nitrogen elements can better fix the metal atoms, better stabilize the crystal structure, reduce the occurrence of lithium-nickel mixing, and improve the safety performance and stability of the material during rapid charging and discharging, which indirectly improves the material's ability to deintercalate lithium and improves the material's capacity.

[0023] 4. Compared with the prior art, the process of the present invention is relatively simple, has a high degree of compatibility with the existing co-precipitation process, does not require equipment changes, and can quickly achieve large-scale production. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0025] First, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] It should be noted that the embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0027] For specific implementation and related comparison, please refer to the following embodiments:

[0028] Example 1

[0029] (1) mixing 1.75 mol of nickel chloride, 0.25 mol of cobalt acetate and 0.5 mol of manganese sulfate to obtain a mixed metal salt solution;

[0030] (2) mixing the mixed metal salt solution, 1.2 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 11 and the ammonia concentration to 0.6 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0031] (3) The low-concentration silk fibroin aqueous solution was replaced with a 5.5 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0032] Example 2

[0033] (1) mixing 1.2 mol of nickel nitrate, 0.4 mol of cobalt chloride and 0.4 mol of manganese acetate to obtain a mixed metal salt solution;

[0034] (2) mixing the mixed metal salt solution, 0.3 wt % low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 9 and the ammonia concentration to 0.1 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0035] (3) The low-concentration silk fibroin aqueous solution is replaced with a 2 wt % high-concentration silk fibroin aqueous solution and the reaction is continued while maintaining the original pH and ammonia concentration. The reaction is stopped after the target D50 is reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0036] Example 3

[0037] (1) mixing 0.3 mol of nickel sulfate, 0.1 mol of cobalt nitrate and 0.1 mol of manganese chloride to obtain a mixed metal salt solution;

[0038] (2) mixing the mixed metal salt solution, 0.3 wt % low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 12 and the ammonia concentration to 0.8 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0039] (3) The low-concentration silk fibroin aqueous solution was replaced with a 4.5 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0040] Example 4

[0041] (1) mixing 0.9 mol of nickel acetate, 0.3 mol of cobalt sulfate and 0.3 mol of manganese nitrate to obtain a mixed metal salt solution;

[0042] (2) mixing the mixed metal salt solution, 1.2 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 11 and the ammonia concentration to 0.9 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0043] (3) The low-concentration silk fibroin aqueous solution was replaced with a 4.5 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0044] Example 5

[0045] (1) mixing 0.05 mol of nickel nitrate, 0.05 mol of cobalt acetate and 0.4 mol of manganese sulfate to obtain a mixed metal salt solution;

[0046] (2) mixing the mixed metal salt solution, 1.2 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 14 and the ammonia concentration to 1 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0047] (3) The low-concentration silk fibroin aqueous solution was replaced with a 5.5 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0048] Example 6

[0049] (1) mixing 0.4 mol of nickel sulfate, 0.05 mol of cobalt chloride and 0.05 mol of manganese acetate to obtain a mixed metal salt solution;

[0050] (2) mixing the mixed metal salt solution, 1.2 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 10 and the ammonia concentration to 0.3 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0051] (3) The low-concentration silk fibroin aqueous solution was replaced with a 5.5 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0052] Example 7

[0053] (1) mixing 0.9 mol of nickel acetate, 0.9 mol of cobalt nitrate and 1.2 mol of manganese chloride to obtain a mixed metal salt solution;

[0054] (2) mixing the mixed metal salt solution, 1.5 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 13 and the ammonia concentration to 0.7 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0055] (3) The low-concentration silk fibroin aqueous solution is replaced with a 3 wt % high-concentration silk fibroin aqueous solution and the reaction is continued while maintaining the original pH and ammonia concentration. The reaction is stopped after the target D50 is reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0056] Example 8

[0057] (1) mixing 2.4 mol of nickel chloride, 0.3 mol of cobalt sulfate and 0.3 mol of manganese nitrate to obtain a mixed metal salt solution;

[0058] (2) mixing the mixed metal salt solution, 0.6 wt % low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 11 and the ammonia concentration to 0.4 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0059] (3) The low-concentration silk fibroin aqueous solution is replaced with a 4 wt % high-concentration silk fibroin aqueous solution and the reaction is continued while maintaining the original pH and ammonia concentration. The reaction is stopped after the target D50 is reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0060] Example 9

[0061] (1) mixing 0.3 mol of nickel acetate, 0.3 mol of cobalt chloride and 2.4 mol of manganese sulfate to obtain a mixed metal salt solution;

[0062] (2) mixing the mixed metal salt solution, 1.2 wt% low-concentration silk fibroin aqueous solution, ammonia water and alkali solution, adjusting the pH of the solution to 11 and the ammonia concentration to 0.4 mol / L, and performing a coprecipitation reaction under a nitrogen atmosphere. When the particle size D50 of the reaction reaches 50% of the target D50, the reaction is suspended to obtain a nitrogen-doped ternary precursor core.

[0063] (3) The low-concentration silk fibroin aqueous solution was replaced with a 6 wt % high-concentration silk fibroin aqueous solution and the reaction was continued while maintaining the original pH and ammonia concentration. The reaction was stopped after the target D50 was reached to obtain a fast-charging ternary precursor material with a nitrogen content gradient distribution.

[0064] Comparative Example 1

[0065] (1) mixing 1.75 mol of nickel chloride, 0.25 mol of cobalt acetate and 0.5 mol of manganese sulfate to obtain a mixed metal salt solution;

[0066] (2) The mixed metal salt solution, ammonia water and alkali solution are mixed, the pH value of the solution is adjusted to 11, the concentration of ammonia water is adjusted to 0.6 mol / L, a coprecipitation reaction is carried out under a nitrogen atmosphere, and the reaction is stopped after the target D50 is reached to obtain a nitrogen-free ternary precursor material.

[0067] Comparative Example 2

[0068] (1) mixing 1.75 mol of nickel chloride, 0.25 mol of cobalt acetate and 0.5 mol of manganese sulfate to obtain a mixed metal salt solution;

[0069] (2) The mixed metal salt solution, 1.2 wt% silk fibroin aqueous solution, ammonia water and alkali solution are mixed, the pH of the solution is adjusted to 11, the ammonia concentration is 0.6 mol / L, and a coprecipitation reaction is carried out under a nitrogen atmosphere. The reaction is stopped after the target D50 is reached to obtain a nitrogen-doped ternary precursor material.

[0070] Comparative Example 3

[0071] (1) mixing 1.75 mol of nickel chloride, 0.25 mol of cobalt acetate and 0.5 mol of manganese sulfate to obtain a mixed metal salt solution;

[0072] (2) The mixed metal salt solution, 8 wt% silk fibroin aqueous solution, ammonia water and alkali solution are mixed, the pH of the solution is adjusted to 11, the ammonia concentration is 0.6 mol / L, and a coprecipitation reaction is carried out under a nitrogen atmosphere. The reaction is stopped after the target D50 is reached to obtain a nitrogen-doped ternary precursor material.

[0073] The fast-charging ternary precursors obtained in the above embodiments and comparative examples were mixed with a lithium source and sintered to obtain the final nitrogen-doped fast-charging ternary positive electrode material, which was assembled into button cells for electrochemical performance testing. Under the voltage window of 3-4.4V, the specific data are as follows:

[0074]

[0075]

[0076] Examples 2 and 3 have the same ratio of nickel source, cobalt source, manganese source and inner core nitrogen content. As the outer shell nitrogen content increases, the discharge capacity retention rate after 4C-200 cycles shows an upward trend.

[0077] Examples 3 and 4 have the same ratio of nickel source, cobalt source, manganese source and outer shell nitrogen content. As the inner core nitrogen content increases, the 0.1C first cycle discharge specific capacity also shows an upward trend.

[0078] Examples 1, 5, and 6 are different ratios of nickel source, cobalt source, and manganese source. Compared with the concentration of the silk fibroin aqueous solution, it can be obtained that the 0.1C first week discharge capacity and the discharge capacity retention rate after 4C-200 cycles are optimal: the molar concentration of nickel element in the mixed metal salt solution is 1.75 mol / L, the molar concentration of cobalt element is 0.25 mol / L, the molar concentration of manganese element is 0.5 mol / L, and the total molar concentration of nickel, iron, and manganese is 2.5 mol / L.

[0079] Example 1 and Comparative Example 1 compare the effects of adding a silk fibroin aqueous solution and not adding a silk fibroin aqueous solution on the 0.1C first week discharge capacity and the discharge capacity retention rate after 4C-200 cycles. Example 1 and Comparative Examples 2 and 3 compare the effects of adding a silk fibroin aqueous solution with gradient concentrations and adding a small amount and an excessive amount of silk fibroin aqueous solution as a whole. It can be seen that adding a suitable silk fibroin aqueous solution has an improving effect on the 0.1C first week discharge capacity and the discharge capacity retention rate after 4C-200 cycles, and not adding or adding a small amount or an excessive amount as a whole will affect the performance.

[0080] It should be noted that the data in the above table are actual test data, and the deviation of nitrogen content at the same silk fibroin concentration is related to the fluctuation of the experimental process.

[0081] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fast-charging ternary precursor material, characterized in that: The precursor material is spherical or quasi-spherical particles, and its material chemical formula is Ni x Co y Mn z (OH)2 or Ni x Co y Mn z CO3, wherein 0.1≤x≤0.8, 0.1≤y≤0.3, 0.1≤z≤0.8, x+y+z=1; the nitrogen content in the precursor material is distributed in various parts of the material in a gradient concentration from low to high from the inside to the outside, the inner core represents the precursor material when the particle size D50 reaches 50% of the target D50, the inner core nitrogen content is 0.11-0.52wt%, and the outer shell nitrogen content is 0.61-1.92wt%.

2. A method for preparing the fast-charging ternary precursor material according to claim 1, characterized in that: The following steps are involved: (1) mixing a nickel source, a cobalt source, and a manganese source to obtain a mixed metal salt solution; (2) mixing a mixed metal salt solution, a low concentration silk fibroin aqueous solution, ammonia water and alkaline solution, and performing a coprecipitation reaction under an inert atmosphere, and pausing the reaction when the particle size D50 of the reaction reaches 50% of the target D50, thereby obtaining a nitrogen-doped ternary precursor core; (3) The low-concentration silk fibroin aqueous solution is replaced with a high-concentration silk fibroin aqueous solution and the reaction is continued. The reaction is stopped after the target D50 is reached, thereby obtaining a fast-charging ternary precursor material with a nitrogen content gradient distribution.

3. The method for preparing a fast-charging ternary precursor material according to claim 2, characterized in that: In the step (1), the molar concentration of nickel in the mixed metal salt solution is 0.05-2.4 mol / L, the molar concentration of cobalt is 0.05-0.9 mol / L, the molar concentration of manganese is 0.05-2.4 mol / L, and the total molar concentration of nickel, cobalt and manganese is 0.5-3.0 mol / L.

4. The method for preparing a fast-charging ternary precursor material according to claim 2, characterized in that: In the step (2), the concentration of the low-concentration silk fibroin aqueous solution is 0.3-1.5 wt %; in the step (3), the concentration of the high-concentration silk fibroin aqueous solution is 2.0-6.0 wt %.

5. The method for preparing a fast-charging ternary precursor material according to claim 2, characterized in that: In the steps (2) and (3), the pH of the coprecipitation reaction is 9 to 14, and the concentration of the ammonia water is 0.1 to 1.0 mol / L.

6. The method for preparing a fast-charging ternary precursor material according to claim 2, characterized in that: The nickel source includes any one or more of nickel chloride, nickel nitrate, nickel sulfate, and nickel acetate; the cobalt source includes any one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate; the manganese source includes any one or more of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate; the alkali solution includes any one of sodium carbonate solution, sodium bicarbonate solution, and sodium hydroxide.

7. A fast-charging ternary cathode material, characterized in that: The fast-charging ternary positive electrode material is prepared by mixing a lithium source and the fast-charging ternary precursor material according to claim 1 and then sintering the mixture.

8. A fast-charge lithium-ion battery, characterized in that: The positive electrode plate of the fast-charging lithium-ion battery comprises the fast-charging ternary positive electrode material as described in claim 7.

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