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CN-122025616-A - Silicon-carbon composite material, negative electrode plate, secondary battery and power utilization device

CN122025616ACN 122025616 ACN122025616 ACN 122025616ACN-122025616-A

Abstract

The application provides a silicon-carbon composite material, a negative electrode plate, a secondary battery and an electric device, wherein the silicon-carbon composite material is particles with a columnar shape, the columnar shape comprises at least one of a waist cylinder and a polygon, the edges of the polygon are in arc transition, the silicon-carbon composite material also comprises titanium element and oxygen element, and the mass content of the silicon element is 5-60% based on the mass of the silicon-carbon composite material. According to the silicon-carbon composite material, the appearance is optimized, so that the conductivity of the anode active material layer can be improved, and the cycle performance and the multiplying power performance of the secondary battery can be improved.

Inventors

  • LU YUHAO
  • ZHENG ZIGUI
  • SHAO WENLONG
  • YI ZHENG

Assignees

  • 宁德新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260416

Claims (11)

  1. 1. The silicon-carbon composite material is characterized by being particles with a columnar shape, wherein the columnar body comprises at least one of a waist cylinder and a polygonal body, the edges of the polygonal body are in arc transition, the silicon-carbon composite material further comprises titanium element and oxygen element, and the mass content of the silicon element is 5-60% based on the mass of the silicon-carbon composite material.
  2. 2. The silicon-carbon composite material according to claim 1, wherein the polygonal body includes at least one of a regular triangular prism-like, a regular quadrangular prism-like, a regular pentagonal prism-like, or a regular hexagonal prism-like.
  3. 3. The silicon-carbon composite of claim 1, wherein the polygon comprises at least one of a regular triangular prism or a regular triangular prism.
  4. 4. The silicon-carbon composite of claim 1 wherein the polygon comprises a regular triangular prism.
  5. 5. The silicon-carbon composite material according to claim 1, wherein the mass content of the titanium element is 0.1% to 1.5%, the mass content of the oxygen element is 0.2% to 1.3%, and the mass content ratio of the oxygen element to the titanium element is 0.9 to 2, based on the mass of the silicon-carbon composite material.
  6. 6. The silicon-carbon composite material according to claim 1, further comprising boron element, wherein the mass content of the boron element is 0.1 to 1%, the mass content of the oxygen element is 0.2 to 1.3%, and the mass content ratio of the oxygen element to the boron element is 0.3 to 1.5 based on the mass of the silicon-carbon composite material.
  7. 7. The silicon-carbon composite of claim 1 wherein the silicon-carbon composite meets at least one of the following characteristics: (1) The Dv50 of the silicon carbon composite material is 3 μm to 15 μm; (2) The specific surface area of the silicon-carbon composite material is 0.5m 2 /g to 50m 2 /g; (3) The X-ray diffraction spectrum of the silicon-carbon composite material contains characteristic peaks of amorphous silicon; (4) The silicon-carbon composite material contains carbon nanotubes, and the outer diameter of the carbon nanotubes is 0.8nm to 20nm.
  8. 8. A negative electrode tab comprising a negative electrode current collector and a negative electrode active material layer on at least one surface of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material comprising the silicon-carbon composite material of any one of claims 1 to 7.
  9. 9. The negative electrode tab of claim 8, wherein the negative electrode active material layer meets at least one of the following characteristics: (1) The silicon-carbon composite material has a mass content of 0.5% to 100% based on the mass of the anode active material; (2) The negative electrode active material layer has a conductivity of 0.1S/cm to 0.6S/cm; (3) When the anode active material is the silicon-carbon composite material, the compacted density of the anode active material layer is 1.2g/cm 3 to 1.56g/cm 3 ; (4) When the anode active material comprises the silicon-carbon composite material and a graphite material, the compacted density of the anode active material layer is 1.4g/cm 3 to 1.8g/cm 3 ; (5) When the anode active material is the silicon-carbon composite material, the porosity of the anode active material layer is 25% to 36%; (6) When the anode active material includes the silicon-carbon composite material and a graphite material, the porosity of the anode active material layer is 15% to 22%.
  10. 10. A secondary battery comprising the negative electrode tab of any one of claims 8 to 9, and a positive electrode tab comprising a positive electrode current collector and a positive electrode active material layer on at least one surface of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material; The positive electrode active material comprises a lithium transition metal oxide, wherein the lithium transition metal oxide comprises at least one of nickel cobalt lithium manganate, nickel cobalt lithium aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate, lithium manganate, lithium iron phosphate and lithium titanate.
  11. 11. An electric device comprising the secondary battery according to claim 10.

Description

Silicon-carbon composite material, negative electrode plate, secondary battery and power utilization device Technical Field The application relates to the field of electrochemical energy storage, in particular to a silicon-carbon composite material, a negative electrode plate, a secondary battery and an electric device. Background As a clean energy source, the application range of secondary batteries has been gradually expanded from consumer electronics to large-sized electric devices such as electric vehicles, energy storage systems, and the like, and higher demands have been made on battery energy density. Graphite negative electrode is still the most widely used negative electrode active material in current commercialization due to its mature technology and good cycle stability, but its theoretical gram capacity is already close to the upper limit (about 372 mAh/g), so that the energy density improvement of graphite-based secondary batteries faces a bottleneck. The theoretical specific capacity of the silicon material is up to 4200 mAh/g, which is regarded as a high-capacity negative electrode with great potential, but the volume expansion of the silicon material is remarkable (up to 300%) in the charge and discharge process, which is easy to lead to pulverization of an electrode structure and falling of active substances, thereby causing rapid reduction of the cycle life and being difficult to meet the actual application demands. The silicon-carbon composite material can buffer volume change to a certain extent by combining high capacity of silicon and structural stability of carbon, and actual reversible capacity can reach 500 mAh/g-2500 mAh/g, so that the silicon-carbon composite material becomes an important development direction of the current high-capacity negative electrode. However, the existing silicon-carbon negative electrode still faces a series of challenges in practical application, namely low first efficiency, high Direct Current Resistance (DCR) and the like, so that the capacity of the silicon-carbon negative electrode is fast attenuated in a long-cycle process, and the problem of insufficient rate performance during high-current charging is solved, and the large-scale application of the silicon-carbon negative electrode in a high-energy-density secondary battery is restricted. Disclosure of Invention In view of the above-mentioned drawbacks of the related art, the present application is directed to providing a silicon-carbon composite material, a negative electrode tab, a secondary battery, and an electric device, so as to solve the problems of the prior art that the silicon-carbon negative electrode has low first efficiency, high Direct Current Resistance (DCR) and thus fast capacity fading in a long cycle process, and insufficient rate capability during high-current charging, and the like, where the silicon-carbon composite material of the present application can improve the conductivity of the negative electrode active material layer, so as to improve the cycle performance and rate capability of the secondary battery. To achieve the above and other related objects, a first aspect of the present application provides a silicon-carbon composite material, which is a particle having a morphology of a columnar body, the columnar body including at least one of a lumbar cylinder and a polygonal body, an edge angle of the polygonal body being in arc transition, an edge of the polygonal body being in arc transition, the silicon-carbon composite material further comprising titanium element and oxygen element, the mass content of the silicon element being 5% to 60% based on the mass of the silicon-carbon composite material. In certain embodiments of the first aspect of the application, the silicon-carbon composite material adopts particles with columnar morphology, the regularity is high, the surface contact among the particles is mainly the surface contact, the bulk density and gram capacity can be effectively improved, the conductivity of a negative electrode active material layer is improved, the impedance of a negative electrode plate is reduced, the silicon element in the silicon-carbon composite material is regulated and controlled within the range, and the silicon-carbon composite material contains titanium element and oxygen element doped with the titanium element, so that the ion conductivity can be improved, a stable titanium oxide interface layer is formed, the volume expansion of silicon particles is inhibited, and the direct current resistance is reduced. Based on the first aspect, in some possible implementations, the polygon satisfies at least one of the following conditions: (1) The polygon comprises at least one of regular triangular prism, regular quadrangular prism, regular pentagonal prism or regular hexagonal prism; (2) The edges and corners of the polygon are in arc transition; (3) The edges of the polygon are in arc transition. Based on the first aspect, in some possible e