Porous silicon-based cathode for lithium battery and preparation method thereof

A lithium-ion battery, porous silicon-based technology, used in battery electrodes, circuits, electrical components, etc., can solve problems such as damage to the internal structure of materials, affecting the cycle performance of electrode materials, and achieve low usage, improved capacity and high current. Discharge performance, effect of improving insertion and extraction speed

Active Publication Date: 2010-11-24
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to solve the problem that the existing silicon-based material is used as a battery negative electrode due to the huge volume change in Li intercalation and extraction, which leads t

Method used

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  • Porous silicon-based cathode for lithium battery and preparation method thereof
  • Porous silicon-based cathode for lithium battery and preparation method thereof
  • Porous silicon-based cathode for lithium battery and preparation method thereof

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specific Embodiment approach 1

[0014] Embodiment 1: The porous silicon-based negative electrode used for lithium-ion batteries in this embodiment consists of a conductive current collector layer and an active layer coated on the conductive current collector layer. The active layer is composed of a silicon active material, a conductive agent and a binder, the porosity of the active layer is 10% to 60%, the average pore diameter is 1nm to 5μm, and the thickness is 0.5 to 200μm, and the silicon active material accounts for 5% to 85% of the total weight of the active layer, so The conductive agent described above accounts for 4% to 70% of the total weight of the active layer, and the binder accounts for 1% to 35% of the total weight of the active layer; the conductive current collector layer is metal copper foil, and the thickness of the metal copper foil is 10 to 35%. 100 μm.

specific Embodiment approach 2

[0015] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the silicon active material is one or a mixture of silicon powder, silicon nanowires, and silicon nanotubes, and the particle size of the silicon powder is 10nm-20μm; the diameter of the silicon nanowire is 10-1000nm, and the length is 1-50μm; the diameter of the silicon nanotube is 10-1000nm, and the length is 1-50μm. Others are the same as in the first embodiment.

[0016] When the silicon active material described in this embodiment is a mixture, each component is in an arbitrary ratio.

specific Embodiment approach 3

[0017] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the conductive agent is copper powder, aluminum powder, nickel powder, copper fiber, aluminum fiber, nickel fiber, acetylene black, carbon black, artificial One or a mixture of graphite, natural graphite, carbon nanotubes and carbon nanofibers. Others are the same as those in the first or second embodiment.

[0018] In this embodiment, when the conductive agent is a mixture, each component is in an arbitrary ratio.

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Abstract

The invention discloses a preparation method of a porous silicon-based cathode for a lithium battery and relates to a battery cathode and a preparation method thereof. In the invention, the problem that the great volume change produced in battery cathodes made of the conventional silicon-based materials during Li embedment and removal leads to destruction of the internal structure of the material and influences the circulation performance of electrode materials is solved. The porous silicon-based cathode for the lithium battery consists of a conductive current collector layer and a high-porosity active layer. The preparation method comprises: dissolving a bonder in a solvent; adding a conductive agent, a silicon active material and a pore forming agent; coating an electrode on the surface of a metal copper foil; and drying, rolling and performing heat treatment in an atmosphere of a protective gas. In the porous silicon-based cathode of the invention, gaps can buffer the volume change of silicon effectively, improve the circulation performance of the silicon-based cathode obviously and improve the contact area between the silicon material and electrolyte; and thus, the lithium ion embedding and removing speeds are improved, and the volume and high-current discharge performance of the silicon cathode can be improved.

Description

technical field [0001] The invention relates to a battery negative electrode and a preparation method thereof. Background technique [0002] At present, most commercial lithium-ion batteries use graphite anodes. Although they have the advantages of high Coulombic efficiency and good cycle performance, their theoretical capacity is very low, which limits the improvement of the specific capacity of the entire battery. Therefore, it is very important to develop new anodes with high specific capacity. Silicon and lithium can form Li 12 Si 7 , Li 7 Si 3 , Li 13 Si 4 and Li 22 Si 5 Li-Si alloys in various phases, such as Li-Si alloys, have a theoretical capacity of up to 4200mAh / g, which is the anode material with the highest theoretical capacity among the various alloy anode materials currently being studied. Moreover, the voltage of lithium intercalation into silicon is lower than 0.5V, and there is no co-intercalation of solvent molecules during the intercalation proc...

Claims

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Application Information

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IPC IPC(8): H01M4/134H01M4/1395
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 杜春雨高翠花尹鸽平史鹏飞程新群左朋建
Owner HARBIN INST OF TECH
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