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CN-116598591-B - Secondary battery and electric equipment

CN116598591BCN 116598591 BCN116598591 BCN 116598591BCN-116598591-B

Abstract

The invention relates to the technical field of secondary batteries, in particular to a secondary battery and electric equipment. A secondary battery includes an electrolyte including an additive including at least one of compounds represented by formula I; wherein X and Y each independently comprise a C1-C20 fluorine-containing and/or silicon-containing hydrocarbon group, R 1 、R 2 、R 3 and R 4 each independently comprise any one of C1-C20 fluorine-containing and/or silicon-containing hydrocarbon groups. The additives in the electrolyte of the secondary battery are coupled through various functions, so that the anode and cathode interface films can be further stabilized, the film forming effect is integrated, and the cycle performance of the battery is further improved.

Inventors

  • XU CAN
  • LV GUOXIAN
  • QIAO FEIYAN
  • CHU CHUNBO

Assignees

  • 欣旺达动力科技股份有限公司

Dates

Publication Date
20260508
Application Date
20230629

Claims (9)

  1. 1. A secondary battery includes an electrolyte including an additive including at least one of compounds represented by formula I; ; wherein X and Y each independently comprise a C1-C20 fluorine-containing and/or silicon-containing hydrocarbon group, Any one of them; R 1 、R 2 、R 3 and R 4 each independently comprise any one of a C1-C20 fluorine-containing and/or silicon-containing hydrocarbon group; The dosage of the additive is 0.1% -5% of the total mass of the electrolyte.
  2. 2. The secondary battery according to claim 1, wherein the additive comprises at least one of compounds represented by formulas I 1 、Ⅰ 2 and I 3 : 、 、 ; R 5 and R 6 each independently comprise any one of C1-C20 fluorine-containing and/or silicon-containing hydrocarbon groups.
  3. 3. The secondary battery according to claim 1, wherein the C1 to C20 fluorine-containing and/or silicon-containing hydrocarbon group includes any one of C1 to C20 fluorine-containing and/or silicon-containing alkyl group, C1 to C20 fluorine-containing and/or silicon-containing alkenyl group, and C1 to C20 fluorine-containing and/or silicon-containing alkynyl group.
  4. 4. The secondary battery according to claim 1, wherein the compound represented by formula I contains silicon-containing hydrocarbon groups, and the number of silicon-containing hydrocarbon groups is greater than 3.
  5. 5. The secondary battery according to claim 1, wherein the additive comprises at least one of compounds represented by the following structural formula: 、 、 、 、 、 。
  6. 6. The secondary battery according to claim 1, wherein the secondary battery comprises a positive electrode sheet including a positive electrode active material including one selected from the group consisting of chemical formulas of Li a Ni x Co y Mn （1-x-y） M e O 2 、LiCoO 2 and LiMn 2 O 4 , wherein 0.9< a <1.1, 0≤e < 0.1,0< x <1,0< y <1, x+y <1, m contains at least one of Al, zr, sr, ti, B, mg, sn, W, Y, ba, nb, mo, ta, si, la, er, nd, gd, ce.
  7. 7. The secondary battery according to claim 1, wherein the secondary battery comprises a positive electrode sheet including a positive electrode current collector and an active material layer provided on at least one surface of the positive electrode current collector, and the thickness of the active material layer of the positive electrode sheet is 20 to 80 μm.
  8. 8. The secondary battery according to claim 1, wherein the secondary battery comprises a negative electrode sheet including a negative electrode current collector and an active material layer provided on at least one surface of the negative electrode current collector, and the active material layer of the negative electrode sheet has a thickness of 30 to 90 μm.
  9. 9. An electric device comprising the secondary battery according to any one of claims 1 to 8.

Description

Secondary battery and electric equipment Technical Field The invention relates to the technical field of secondary batteries, in particular to a secondary battery and electric equipment. Background The lithium ion battery has the advantages of high working voltage, long service life and the like, and along with the continuous development of technology, the energy density, the cycle life and the safety requirements of people on the lithium ion battery are continuously improved. In the use process of the lithium ion battery, the battery is possibly in a high-temperature and high-pressure state due to factors such as the rise of the ambient temperature, so that the reactivity of the positive electrode is enhanced, and the electrolyte reacts with the positive electrode material, thereby bringing great challenges to practical application. Among these, the development of adapted electrolyte additives is one of the most cost-effective methods for improving the electrochemical performance of lithium ion batteries. Therefore, the design of a film forming additive for improving the positive electrode interface film is very important for further improving the comprehensive performance of the high-power system battery. In view of this, the present invention has been made. Disclosure of Invention An object of the present invention is to provide a secondary battery in which an electrolyte can simultaneously form a passivation film having a small and stable impedance at both positive and negative electrode interfaces, protect the positive and negative electrodes, and suppress transient side reactions. Another object of the present invention is to provide an electric device, which includes the above secondary battery. In order to achieve the above object of the present invention, the following technical solutions are adopted: A secondary battery includes an electrolyte including an additive including at least one of compounds represented by formula I; wherein X and Y each independently comprise a C1-C20 fluorine-containing and/or silicon-containing hydrocarbon group, Any one of them; R 1、R2、R3 and R 4 each independently comprise any one of C1-C20 fluorine-containing and/or silicon-containing hydrocarbon groups. Further, the additive includes at least one of the compounds shown in formulas I 1、Ⅰ2 and I 3: R 5 and R 6 each independently comprise any one of C1-C20 fluorine-containing and/or silicon-containing hydrocarbon groups. Further, the C1-C20 fluorine-containing and/or silicon-containing hydrocarbon group comprises any one of C1-C20 fluorine-containing and/or silicon-containing alkyl, C1-C20 fluorine-containing and/or silicon-containing alkenyl and C1-C20 fluorine-containing and/or silicon-containing alkynyl. Further, the compound shown in the formula I comprises silicon-containing hydrocarbon groups, and the number of the silicon-containing hydrocarbon groups is more than 3. Further, the additive comprises at least one of the compounds shown in the following structural formula: further, the dosage of the additive is 0.1% -5% of the total mass of the electrolyte. Further, the secondary battery includes a positive electrode sheet including a positive electrode active material including one of the chemical formulas Li aNixCoyMn(1-x-y)MeO2、LiCoO2 and LiMn 2O4, wherein 0.9< a <1.1, 0≤e≤0.1, 0< x <1,0< y <1, x+y <1, M contains at least one of Al, zr, sr, ti, B, mg, sn, W, Y, ba, nb, mo, ta, si, la, er, nd, gd, ce. Further, the secondary battery comprises a positive plate, wherein the positive plate comprises a positive current collector and an active material layer arranged on at least one surface of the positive current collector, and the thickness of the active material layer of the positive plate is 20-80 mu m. Further, the secondary battery comprises a negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector and an active material layer arranged on at least one surface of the negative electrode current collector, and the thickness of the active material layer of the negative electrode plate is 30-90 mu m. The invention also provides electric equipment, which comprises any one of the secondary batteries. Compared with the prior art, the invention has the beneficial effects that: (1) The secondary battery of the invention has the advantages that the additive in the electrolyte contains P-O bond, free radical generated by the breakage of the P-O bond is diffused to the surface of the positive electrode to form CEI film, thus being capable of inhibiting the dissolution of transition metal at the interface of the positive electrode, and the central atom B of the additive is in electron-deficient state, thus being capable of being used as an anion receptor to improve the dissociation degree of lithium salt and the migration number of lithium ion, reducing the content of LiF at the surface of the electrode and further reducing interface impedance; (2) The electrolyte of the