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Silica negative electrode material and preparation method thereof

A negative electrode material, silicon-oxygen technology, applied in the field of silicon-oxygen negative electrode materials and its preparation, can solve the problems of volume expansion, reversible capacity reduction, battery cycle performance deterioration, etc.

Active Publication Date: 2021-04-20
SHENZHEN DYNANONIC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of this application is to provide a silicon-oxygen negative electrode material and its preparation method, as well as a lithium-ion battery, aiming to solve the problem of the volume expansion and contraction of the existing negative electrode material silicon oxide in the process of inserting and removing lithium, resulting in constant reversible capacity. decrease, battery cycle performance deterioration

Method used

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preparation example Construction

[0083] The second aspect of the embodiment of the present application provides a method for preparing a silicon-oxygen negative electrode material, including:

[0084] Using silicon oxide and carbon sources as raw materials, a core-shell structure with a core, a middle layer and an outer shell layer is prepared under dynamic heat preservation conditions.

[0085] Wherein, the intermediate layer is coated on the surface of the inner core, and the outer shell is coated on the surface of the intermediate layer,

[0086] The material of the inner core includes amorphous silicon oxide silicon oxide and silicon microcrystal, and along the direction from the center of the inner core to the surface of the inner core, the size of the silicon microcrystal increases gradually; the material of the middle layer is silicon carbide.

[0087] The preparation method of the silicon-oxygen negative electrode material provided in the embodiment of the present application uses silicon oxide and ca...

Embodiment 1

[0120] A method for preparing a silicon-oxygen negative electrode material, comprising:

[0121] 1kg SiO x The negative electrode material is placed in the rotary furnace, and the gas in the rotary furnace is replaced by Ar to ensure complete evacuation; after turning on the heating and raising the temperature to 750 °C at 5 °C / min, switch to acetylene / Ar mixed gas, and then dynamically keep the temperature for 1.5 hours. The surface layer of the material is uniformly covered with a carbon layer; switch the gas to Ar, further raise the temperature to 1200°C at 5°C / min and keep it for 20 minutes, and take out the material after falling to room temperature under the protection of a non-oxidizing gas to obtain conductive silicon with a silicon microcrystalline gradient distribution structure Oxygen complexes were analyzed by a carbon-sulfur analyzer to obtain a carbon coating amount of 3.0 wt%.

Embodiment 2

[0123] A method for preparing a silicon-oxygen negative electrode material, comprising:

[0124] 1kg SiO x After mixing evenly with 80g of petroleum-based asphalt through a high-temperature coating machine, place it in a rotary furnace and replace it with Ar to ensure complete evacuation. Turn on the heating and raise the temperature to 1150°C at 5°C / min and then keep it dynamic for 2 hours. The surface of the material is completely carbonized The material was taken out after being lowered to room temperature under the protection of a non-oxidizing gas, and a conductive silicon-oxygen composite with a silicon crystallite gradient distribution structure was obtained, and a carbon coating amount of 5.1wt% was obtained by analyzing with a carbon-sulfur analyzer.

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Abstract

The invention relates to the technical field of battery negative electrode materials, and provides a silica negative electrode material and a lithium ion battery. The silica negative electrode material has a core-shell structure and comprises an inner core, a middle layer coating the surface of the inner core and an outer shell layer coating the surface of the middle layer; the material of the inner core comprises amorphous silicon oxide and silicon microcrystals, and the sizes of the silicon microcrystals are increased in a gradient manner along the direction from the center of the inner core to the surface layer of the inner core; the middle layer is made of silicon carbide; and the outer shell layer comprises a carbon layer. The negative electrode core material with the characteristics can guide huge volume expansion stress generated in a lithium embedding process to be released outwards through silicon microcrystals which are distributed in an amorphous silicon oxide main body material and have gradually changed sizes, so that volume expansion of the silicon-based negative electrode material is inhibited, and irreversible capacity increase caused by volume expansion is reduced; therefore, the cycle life of the silicon-based negative electrode material is effectively prolonged.

Description

technical field [0001] The application belongs to the technical field of battery anode materials, and in particular relates to a silicon-oxygen anode material and a preparation method thereof. Background technique [0002] Lithium-ion secondary battery is the most competitive battery of the new generation, known as "green energy", and is the preferred technology to solve contemporary environmental pollution and energy problems. In recent years, lithium-ion secondary batteries have achieved great success in the field of high-energy batteries, but consumers still expect batteries with higher comprehensive performance, which depends on the research and development of new electrode materials and electrolyte systems. [0003] The theoretical reversible capacity of the anode material silicon oxide reaches 2007mAh / g, and its cycle performance is excellent, which is the key anode material for increasing energy density. However, in the process of repeated intercalation and desorptio...

Claims

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Application Information

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IPC IPC(8): H01M4/38H01M4/485H01M4/62H01M10/0525
CPCY02E60/10
Inventor 钟泽钦万远鑫孔令涌任望保朱成奔张於财钟文
Owner SHENZHEN DYNANONIC
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