CNT-Coated Ni-Rich Cathode Material for Stable Fast-Charging
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Solution Overview
Problem
Ni-rich positive electrode active materials in lithium secondary batteries suffer from poor electron conductivity and surface instability, leading to increased resistance and reduced lifespan due to electrochemical side reactions and cell-swelling phenomena, limiting their high-speed charging and discharging performance.
Innovation Solution
A method of physically attaching carbon nanotubes to the surface of Ni-rich positive electrode active materials using a milling machine to form a carbon nanotube coating layer, enhancing electron conductivity and surface stability while maintaining the crystalline structure, with a carbon nanotube content of 1-5 wt% and a thickness of 5-21 nm, facilitating mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Ni-rich positive electrode active materials are used to achieve high energy density, then the energy density is improved, but the electron conductivity and surface stability deteriorate
Solution Approach 1:
The patent applies composite materials by forming a carbon coating layer on the Ni-rich positive electrode active material surface. This composite structure combines the high energy density benefits of Ni-rich materials with the surface stability and conductivity of carbon, resolving the contradiction between energy density and surface stability.
Solution Approach 2:
The patent applies local quality by modifying only the surface region of the positive electrode active material with a carbon coating layer. The bulk material maintains its Ni-rich composition for high energy density, while the surface acquires carbon properties for improved stability and conductivity, resolving the contradiction through localized modification.
2Reliability
If carbon coating is applied to improve electron conductivity and surface stability, then the conductivity and stability are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces complex chemical carbonization processes with a simpler physical coating method. By using mechanical or physical means to deposit carbon on the material surface, the manufacturing process becomes less complex while still achieving the desired electron conductivity improvement.
3Reliability
If high-temperature carbonization is performed to achieve high conductive carbonization, then the electron conductivity is improved, but the material stability deteriorates due to carbon thermal reduction
Solution Approach 1:
The patent changes the carbonization temperature parameter to a lower range that avoids carbon thermal reduction while still achieving sufficient carbon conductivity. This parameter optimization resolves the contradiction between achieving high electron conductivity and maintaining material stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach stabilizes the surface of Ni-rich positive electrode materials, improving electron conductivity and retaining high energy density, thereby extending the lifespan and performance of lithium secondary batteries, particularly suitable for electric vehicles, and reducing manufacturing costs.
Implementation Method 1
A method of physically attaching carbon nanotubes to the surface of Ni-rich positive electrode active materials using a milling machine
Implementation Method 2
enhancing electron conductivity
Data Source
AI summary
A positive electrode material for a lithium secondary battery and a manufacturing method therefor are provided. The positive electrode material may have carbon nanotubes stably attached to a surface of an active material and may exhibit increased electron conductivity and improved surface stability. The positive electrode material for a lithium secondary battery may comprises: a positive electrode active material core comprising a Li—Ni—Co—Mn-M-O-based material, where M is a transition metal; and a carbon nanotube coating layer on a surface of the positive electrode active material core. Carbon nanotubes (CNT) may be in an amount of 1-5 wt %, based on 100 wt % of the positive electrode active material core.