CN-122000358-A - Organic-inorganic composite lithium supplementing agent and preparation method thereof

CN122000358ACN 122000358 ACN122000358 ACN 122000358ACN-122000358-A

Abstract

The invention provides an organic-inorganic composite lithium supplementing agent and a preparation method thereof, and relates to the technical field of lithium batteries. The organic-inorganic composite lithium supplementing agent comprises an inorganic lithium supplementing agent and an organic lithium supplementing agent, wherein the organic lithium supplementing agent is coated on the surface of the inorganic lithium supplementing agent to form a coating layer. The structure effectively isolates water and oxygen by utilizing the organic coating layer, solves the problem that the inorganic material is easy to absorb water and lose efficacy, and simultaneously utilizes the inorganic core to provide electric conduction and catalysis effects, thereby improving the reaction kinetics and lithium supplementing efficiency of the organic material. And the organic decomposition products can form a film in situ, and inhibit electrolyte side reactions caused by inorganic residues, so that the high stability and the high electrochemical performance are both achieved.

Inventors

WANG YINGMEI
HE KUANG
QIN KAI
YANG TIANXIANG
SHAO HONGMING
JIN YIZHONG
WANG JIANBIN
YIN XINYU

Assignees

浙江永太新能源材料有限公司
浙江永太科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (9)

1. An organic-inorganic composite lithium supplementing agent is characterized by comprising an inorganic lithium supplementing agent and an organic lithium supplementing agent; wherein the organic lithium supplementing agent is coated on the surface of the inorganic lithium supplementing agent to form a coating layer; the organic lithium supplementing agent comprises at least one of compounds shown as a general formula R-SO 2 Li; Wherein R is selected from any one of halogen, C1-C5 alkyl, C1-C5 alkoxy, aryl, heteroaryl, silyl or siloxane, wherein the C1-C5 alkyl, C1-C5 alkoxy, aryl, heteroaryl, silyl or siloxane is unsubstituted or substituted with one or more substituents selected from halogen, cyano, alkyl, alkoxy, alkenyl and alkynyl; the organic-inorganic composite lithium supplementing agent also comprises a conductive auxiliary agent, wherein the conductive auxiliary agent is dispersed in the coating layer and the inside of the coating layer.
2. The organic-inorganic composite lithium-supplementing agent according to claim 1, wherein said inorganic lithium-supplementing agent comprises at least one of Li 2 NiO 2 and Li 5 FeO 4 , and/or, The surface of the inorganic lithium supplementing agent is provided with a carbon coating layer or a non-coating layer, and/or, The inorganic lithium supplementing agent is doped with metal elements or is doped with no metal elements, and the metal elements comprise at least one of Mg, al and Zr.
3. The organic-inorganic composite lithium-supplementing agent according to claim 1, wherein the conductive auxiliary agent is at least one selected from the group consisting of conductive carbon black, conductive graphite, carbon nanotubes, graphene, MXene and carbon fibers, and/or, The organic-inorganic composite lithium supplementing agent also comprises a dispersing agent, wherein the dispersing agent is at least one selected from polyethylene glycol and sodium dodecyl benzene sulfonate.
4. A method for preparing the organic-inorganic composite lithium supplement according to any one of claims 1 to 3, wherein the preparation method comprises dry-mixed coating or wet-mixed coating.
5. The method for preparing an organic-inorganic composite lithium-supplementing agent according to claim 4, wherein the dry-mixed coating comprises: mixing an inorganic lithium supplementing agent, an organic lithium supplementing agent and a dispersing agent, and stirring for 20-30 min at 2000-3000 rpm to obtain a premixed material; adding a conductive auxiliary agent into the pre-mixed material, ball-milling for 1-2 hours at 300-400 rpm under vacuum or inert atmosphere, heating to 50-100 ℃, ball-milling for 2-4 hours at 500-800 rpm, sieving to obtain the organic-inorganic composite lithium supplement agent, and/or, The wet mixed coating comprises the following steps: dissolving an organic lithium supplementing agent and a dispersing agent in a solvent to form an organic lithium supplementing agent solution; Adding an inorganic lithium supplementing agent and a conductive auxiliary agent into the organic lithium supplementing agent solution, and after dispersing, heating to 50-100 ℃ for reaction for 2-4 hours to obtain a mixed solution; And carrying out spray drying on the mixed solution to obtain the organic-inorganic composite lithium supplementing agent, wherein the inlet temperature of the spray drying is 180-200 ℃ and the outlet temperature is 80-100 ℃.
6. A positive electrode sheet, characterized by comprising a positive electrode active material, a conductive agent, a binder, and the organic-inorganic composite lithium-supplementing agent according to any one of claims 1 to 3.
7. The positive electrode sheet according to claim 6, wherein the mass ratio of the organic-inorganic composite lithium-supplementing agent to the positive electrode active material is (0.001-2): 1, and/or, The positive electrode active material includes at least one of an olivine-type structural material, a spinel-type structural material, or a layered oxide positive electrode material; the general formula of the positive electrode active material comprises LiM z N 1-z PO 4 、Li 1+x Ni y Mn 2-x-y O 4 or Li 1+a Ni b Co c M' 1-a-b-c O 2 , wherein M and N are respectively one of Fe, mn, co and Ni, M' is at least one of Mg, al, ca, sc, ti, V, cr, mn, fe, zn, ga, Y, zr, nb, mo, sn, ba and rare earth elements, z is more than or equal to 0 and less than or equal to 1, x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, a is more than or equal to 0 and less than or equal to 0.5, b is more than or equal to 0 and less than or equal to 1, c is more than or equal to 0 and less than or equal to 1, and a+b+c is more than or equal to 0 and less than or equal to 1.
8. A lithium secondary battery comprising a separator, an electrolyte, a negative electrode sheet, and the positive electrode sheet according to claim 6 or 7.
9. An electric device comprising the lithium secondary battery according to claim 8.

Description

Organic-inorganic composite lithium supplementing agent and preparation method thereof Technical Field The invention relates to the technical field of lithium batteries, in particular to an organic-inorganic composite lithium supplementing agent and a preparation method thereof. Background Lithium ion batteries have been widely used in the fields of mobile electronic devices, electric vehicles, energy storage systems, and the like due to their high energy density and long cycle life. With the continuous improvement of the endurance requirements of the application end, the development of a battery system with higher energy density has become a core requirement of industry development. However, in the lithium ion battery, during the first charging process, the electrolyte solution may undergo decomposition reaction at the surfaces of the positive and negative electrodes to form a solid electrolyte interface film (SEI film or CEI film), which inevitably consumes part of the active lithium ions from the positive electrode. Particularly, for high-specific capacity electrode materials such as a high-nickel ternary anode, a silicon-carbon cathode and the like, the consumption of active lithium in the primary charging process is huge due to the large specific surface area or remarkable volume expansion effect, so that the primary coulomb efficiency of the battery is reduced, obvious irreversible capacity loss is caused, and the practical energy density of the battery is seriously restricted. In order to solve the problem of active lithium loss, the positive electrode lithium supplementing technology is a current research hot spot. According to the technology, the lithium supplement additive with high irreversible capacity is added into the positive electrode plate, and the additional active lithium source released by decomposition in the first charging process is utilized to compensate lithium loss in the SEI film formation and subsequent circulating process. The existing positive electrode lithium supplementing agent is mainly divided into an inorganic lithium supplementing agent and an organic lithium supplementing agent. The inorganic lithium supplementing agent is mainly represented by lithium-rich transition metal oxides (such as lithium ferrite and lithium nickelate), and the organic lithium supplementing agent is mainly represented by organic lithium salts such as lithium oxalate. However, both existing lithium supplements have significant drawbacks in practical applications. For the inorganic lithium supplementing agent, the surface of the inorganic lithium supplementing agent is generally high in residual alkali content, is extremely sensitive to moisture and air in the environment and is extremely easy to absorb water and deteriorate and lose efficacy, so that the environmental dew point control requirements are extremely strict in the slurry preparation and pole piece coating processes, and the processing difficulty and cost are increased. In addition, the decomposition products after delithiation of the inorganic lithium-supplementing agent are usually catalytically active transition metal oxides, and these residues continue to catalyze electrolyte decomposition, not only accelerating consumption of active lithium, but also deteriorating stability of the electrode/electrolyte interface, resulting in degradation of battery cycle performance. On the other hand, organic lithium-supplementing agents generally have poor electron conductivity and high oxidative decomposition potential. In the absence of a catalyst, organic lithium-supplementing agents tend to be difficult to completely decompose during charging, resulting in low lithium supplementing efficiency, and the non-decomposed residues as inert components reduce the energy density of the battery. While the kinetic properties can be improved by adding conductive carbon or metal catalysts, this often involves a complex coating process. In summary, how to obtain a lithium-supplementing material with excellent environmental stability, high lithium-supplementing efficiency and good interface compatibility is a problem to be solved in the technical field of current lithium ion batteries. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide an organic-inorganic composite lithium supplementing agent and a preparation method thereof, wherein the composite structure improves environmental stability through organic coating, enhances conductivity and reaction kinetics by utilizing an inorganic core, inhibits interface side reaction, and realizes the synergy of high lithium supplementing efficiency and long cycle life. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: in a first aspect, the present invention provides an organic-inorganic composite lithium-supplementing agent, including an inorganic lithium-supplementing agent and an organ