CN-121983545-A - Lithium-rich manganese-based positive electrode material, inorganic-rich positive electrode-electrolyte interface, and preparation methods and applications thereof

CN121983545ACN 121983545 ACN121983545 ACN 121983545ACN-121983545-A

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, an inorganic-rich positive electrode-electrolyte interface, and a preparation method and application thereof. According to the invention, the metal nanoclusters with catalytic activity are uniformly loaded on the surface of the lithium-rich manganese-based positive electrode material, and the metal nanoclusters are utilized to selectively catalyze the decomposition of lithium salt in the electrolyte in the electrochemical process, so that an interface layer mainly taking inorganic components as main components is formed in situ, and the interface layer mainly comprises inorganic matters with high ion conductivity and stable mechanics, such as LiF, li 2 O、Li 3 N and the like. The inorganic-rich positive electrode-electrolyte interface can remarkably improve the structural stability and interface ion transmission efficiency of the lithium-rich manganese-based positive electrode material under the high-voltage condition, effectively inhibit the dissolution of transition metal and the release of lattice oxygen, and further improve the cycle stability and the rate capability of the battery. The method has the advantages of simple process, mild condition and easy large-scale implementation, and is suitable for the positive electrode material of the lithium ion battery with high energy density.

Inventors

SUN WENPING
LIU JIABING
ZHANG XIAOMIN
PAN HONGGE
GAO MINGXIA

Assignees

浙江大学

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (10)

1. The lithium-rich manganese-based positive electrode material is characterized in that the surface of the lithium-rich manganese-based positive electrode material is loaded with uniformly dispersed metal nanoclusters M, and the composition of the lithium-rich manganese-based positive electrode material is M-Li a Mn b Ni c Co d O 2 ; The metal nanoclusters M include at least one of Ru, rh, pd, ag, ir, pt, au; Wherein, the a is more than or equal to 1.15 and less than or equal to 1.30,0.50 and b is more than or equal to 0.60,0.10 c is more than or equal to 0.20,0.10, d is more than or equal to 0.20, and a+b+ c+d=2.
2. The lithium-rich manganese-based positive electrode material according to claim 1, wherein the metal nanocluster M is Pt, and the size of the metal nanocluster M is 1-10 nm.
3. The method for preparing the lithium-rich manganese-based positive electrode material according to claim 1, which is characterized by comprising the following specific steps: S1, mixing metal salt solutions of lithium, manganese, nickel and cobalt, adding a complexing agent, stirring, performing ultrasonic treatment to obtain a precursor solution of a lithium-rich manganese-based positive electrode material, preparing a precursor of the lithium-rich manganese-based positive electrode material, and performing pyrolysis treatment on the precursor of the lithium-rich manganese-based positive electrode material to obtain a matrix of the lithium-rich manganese-based positive electrode material; S2, adding the lithium-rich manganese-based positive electrode material matrix and the metal salt obtained in the step S1 into a solvent according to a preset feeding proportion, and uniformly dispersing the materials by ultrasonic waves; and S3, carrying out high-temperature annealing treatment on the mixture obtained in the step S2 under the condition of inert atmosphere to obtain the lithium-rich manganese-based anode material with the metal nanocluster M loaded on the surface.
4. A method of preparing according to claim 3, wherein in S1 the stoichiometric ratio of lithium, manganese, nickel and cobalt is 1.03a:b:c:d, wherein: a is more than or equal to 1.15 and less than or equal to 1.30,0.50 and less than or equal to b is more than or equal to 0.60,0.10 and less than or equal to c and less than or equal to 0.20,0.10, d is more than or equal to 0.20, and a+b+c+d=2; and/or in S1, the complexing agent is citric acid; and/or in S1, stirring at 400-600 rpm for 1-3 h; And/or in S1, the ultrasonic time is 20-40 min; and/or, in S1, preparing a precursor of the lithium-rich manganese-based positive electrode material by at least one of a spray drying method, a coprecipitation method, a sol-gel method, a high temperature solid phase method or a molten salt method, preferably, preparing the precursor of the lithium-rich manganese-based positive electrode material by a spray drying method; And/or S1, wherein the spray drying feeding rate is 3-15 mL/min, the air inlet temperature is 200-250 ℃, and the air outlet temperature is 100-120 ℃; And/or in S1, the pyrolysis treatment is carried out by heating to 850-950 ℃ at a heating rate of 2-5 ℃ min -1 under the air atmosphere, and preserving heat for 8-12 h.
5. The method according to claim 3, wherein in S2, the metal salt is at least one selected from the group consisting of Ru, rh, pd, ag, ir, pt, au metal chloride, metal nitrate and acetylacetonate; And/or in S2, the mass ratio of the lithium-rich manganese-based positive electrode material matrix to the corresponding metal atoms is 100:1-1000:1; and/or in S2, the ultrasonic treatment time is 10-60 min; And/or in S2, continuously stirring and evaporating to dryness at a speed of 300-1200 rpm and a temperature of 40-80 ℃ for 2-12 hours; And/or in S2, the solvent is at least one selected from deionized water, absolute ethyl alcohol, acetone and N-methyl pyrrolidone, and the dosage ratio of the solvent to the lithium-rich manganese-based positive electrode material matrix is 5-40:1 mL/g; And/or, in S3, the inert atmosphere is argon or nitrogen; and/or in S3, the annealing temperature is 250-500 ℃ and the annealing time is 2-10 h.
6. The method for constructing the inorganic anode-electrolyte interface of the lithium-rich manganese-based anode material is characterized by comprising the following steps of: Introducing metal nanocluster catalytic sites into the surface of the lithium-rich manganese-based positive electrode material matrix according to claim 1, and inducing the preferential decomposition of lithium salt in the electrolyte, so as to construct an inorganic-rich positive electrode-electrolyte interface.
7. The construction method of claim 6, wherein the method comprises the steps of uniformly dispersing the lithium-rich manganese-based positive electrode material, conductive carbon, a binder and a solvent to obtain positive electrode slurry, coating the positive electrode slurry on the surface of a current collector, drying, slicing and rolling to obtain a lithium-rich manganese-based positive electrode sheet, matching a lithium metal negative electrode, an electrolyte and a diaphragm, assembling under an inert atmosphere to obtain the lithium ion battery, and promoting the preferential decomposition of lithium salt in the initial charge-discharge process by utilizing the selective adsorption and catalysis of metal nanoclusters on the surface of the lithium-rich manganese-based positive electrode material, thereby constructing an inorganic-rich positive electrode-electrolyte interface on the surface of the lithium-rich manganese-based positive electrode material.
8. The method of claim 7, wherein the inorganic-rich anode-electrolyte interface is formed by selective adsorption of surface metal nanocluster catalytic sites and preferential decomposition of lithium salt in the catalytic electrolyte during charge and discharge, and comprises at least one of LiF and Li 2 O、Li 3 N; And/or the lithium salt in the electrolyte comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalato borate and lithium bistrifluoromethane sulfonyl imide; and/or the solvent of the electrolyte is an ester solvent, preferably at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate and ethyl acetate; And/or the conductive agent is at least one selected from graphite, acetylene black, super P, carbon nanotubes, graphene and ketjen black; And/or the binder is at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose and sodium alginate; And/or the current collector is selected from at least one of aluminum foil, carbon-coated aluminum foil, nickel foil and stainless steel foil; and/or the solvent is deionized water or N-methyl pyrrolidone.
9. The inorganic-rich positive electrode-electrolyte interface of a lithium-rich manganese-based positive electrode material obtained by the construction method according to any one of claims 6 to 8.
10. Use of the construction method according to any one of claims 6 to 8 or the inorganic-rich positive electrode-electrolyte interface of the lithium-rich manganese-based positive electrode material according to claim 9 in a lithium ion battery.

Description

Lithium-rich manganese-based positive electrode material, inorganic-rich positive electrode-electrolyte interface, and preparation methods and applications thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, an inorganic-rich positive electrode-electrolyte interface, and a preparation method and application thereof. Background The information disclosed in the background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an admission or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. In the positive electrode material system of the lithium ion battery, the lithium-rich manganese-based positive electrode material has high specific discharge capacity (> 250 mAh g -1) and high working voltage (3.6V) and is regarded as the positive electrode material of the next-generation high specific energy lithium ion battery. However, when the lithium-rich manganese-based positive electrode material circulates under a high-voltage condition, irreversible precipitation of lattice oxygen and surface structure degradation are easy to occur, continuous capacity attenuation and voltage degradation are caused, and practical application of the material is restricted. Research shows that the composition and structural characteristics of the anode-electrolyte interface play a vital role in the electrochemical stability and long-cycle performance of the lithium-rich manganese-based material. In a traditional lithium ion battery system, the highest occupied molecular orbital energy of electrolyte solvent molecules is higher than that of lithium salt anions, so that in a high-voltage working window of a lithium-rich manganese-based positive electrode material, the solvent molecules are more prone to be subjected to oxidative decomposition on the surface of the positive electrode preferentially. This reaction path tends to produce organic components such as lithium alkyl carbonate. The positive electrode-electrolyte interface rich in organic components has low mechanical modulus and poor chemical stability, is easy to crack and reconstruct in the electrochemical circulation process, continuously consumes limited lithium sources and electrolyte, and can further aggravate the dissolution of transition metal ions and the release of lattice oxygen in the lithium-manganese-based positive electrode material, and finally leads to the increase of battery impedance and performance failure. Aiming at the problem of unstable interface of the lithium-rich manganese-based anode material in the circulation process, the prior art is mainly regulated and controlled by means of surface inert coating (such as metal oxide, fast ion conductor and the like), electrolyte optimization and the like. However, the conventional surface coating technology often has difficulty in realizing accurate regulation and control of the thickness and distribution of the coating layer, and the interface binding force between the coating layer and the substrate is weak, so that peeling easily occurs in long-term circulation, and the inhibition effect of the coating layer on the interface side reaction is difficult to last. Although the electrolyte optimization strategy adjusts the chemical environment of the interface to a certain extent, the thermodynamic trend of the electrolyte components which are decomposed preferentially under high voltage is difficult to change fundamentally, so that the electrode-electrolyte interface is still mainly composed of organic components, the mechanical strength and the electrochemical stability are both insufficient, and the long-term circulation requirement of the lithium-rich manganese-based positive electrode material under high working voltage is difficult to meet. Disclosure of Invention In view of the above, the invention provides a lithium-rich manganese-based positive electrode material, an inorganic-rich positive electrode-electrolyte interface, and a preparation method and application thereof. According to the invention, the catalytic active site is introduced on the surface of the lithium-rich manganese-based positive electrode material, so that the limitation of the reaction path of the traditional positive electrode-electrolyte interface is broken through, the lithium salt is induced to decompose preferentially and the generation of inorganic components is promoted, and therefore, a stable and compact inorganic-rich positive electrode-electrolyte interface which is applicable to high-voltage conditions is constructed, and the cycle stability and electrochemical performance of the lithium-rich manganese-based positive electrode material are improved. In order to achieve the above object, the present invention is realized by the following technical schem