Coated Lithium Battery Cathode for Thermal Safety
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with thermal safety and cycle-life characteristics, particularly with Co—Ni—Mn ternary lithium metal composite oxides, which have limitations in capacity and stability.
Innovation Solution
A positive active material for rechargeable lithium batteries is developed, comprising a core of nickel-based composite oxide or lithium manganese oxide coated with a lithium metal oxide, specifically designed to enhance thermal safety and cycle-life performance, achieved through a heat-treatment process that includes a sol-gel method using tetravalent elements like Zr or Ti.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Co—Ni—Mn ternary lithium metal composite oxide is used as positive active material, then capacity is improved, but thermal safety and cycle-life characteristics deteriorate
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where the core is Co-Ni-Mn ternary lithium metal composite oxide and the shell is lithium metal oxide coating layer. This composite structure allows the inner core to provide high capacity while the outer shell provides thermal safety and improved cycle-life characteristics, effectively resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent applies local quality by creating a coated structure where the surface properties differ from the bulk properties. The core material maintains its high capacity characteristics in the interior, while the surface is modified with lithium metal oxide coating to provide thermal stability and cycle-life improvement, allowing different regions to have different functional qualities.
2Stability of the object's composition
If LiCoO2 is used as positive active material, then electrochemical stability is improved, but capacity is limited
Solution Approach 1:
The patent uses composite materials by combining LiCoO2 with other lithium metal oxides in a coated structure. The LiCoO2 core provides electrochemical stability while the additional lithium metal oxide shell contributes to enhanced capacity, allowing the system to achieve both stability and high capacity simultaneously.
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 coated positive active material achieves high capacity, improved thermal safety, and extended cycle-life characteristics, as demonstrated by XRD patterns and DSC curves showing enhanced stability and performance in rechargeable lithium batteries.
Implementation Method 1
heat-treating the mixture to coat a surface of the core material with a lithium metal oxide
Implementation Method 2
X-ray diffraction pattern using a CuKα ray
Implementation Method 3
peak at a 2θ value of about 19° to about 22° and another peak at a 2θ value of about 40° to about 45°
Implementation Method 4
heat-treating the mixture to coat a surface of the core material with a lithium metal oxide
Data Source
AI summary
A positive active material for a rechargeable lithium battery including a core including at least one selected from a nickel-based composite oxide represented by Chemical Formula 1 or a lithium manganese oxide represented by Chemical Formula 2; and a coating layer on a surface of the core and including a lithium metal oxide represented by Chemical Formula 3, the positive active material having a peak at a 2θ value of about 19° to about 22° and another peak at a 2θ value of about 40° to about 45° in an X-ray diffraction pattern using a CuKα ray, is disclosed. A method of preparing the same, and a rechargeable lithium battery including the same, are also disclosed.LiNixCoyMn1-x-yO2 Chemical Formula 1LiaMnbOc Chemical Formula 2Li2MO3 Chemical Formula 3In Chemical Formulae 1 to 3, x, y, a, b, c, and M are the same as in the detailed description.