Lithium Cobalt Oxide Composite with Lithium Titanium Oxide Coating
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Solution Overview
Problem
Lithium cobalt oxide-based positive electrode materials in lithium secondary batteries face challenges with stability at high voltages and high temperatures, leading to phase transitions and capacity degradation, and existing doping methods like aluminum do not provide satisfactory high-voltage characteristics.
Innovation Solution
A composite positive electrode active material is developed, comprising lithium cobalt oxide particles with a particle coating layer of lithium titanium oxide and a surface coating layer, along with a lithium-deficient cobalt oxide phase, which is prepared through a method involving heat-treatment of precursor mixtures containing cobalt, titanium, and zirconium, enhancing structural stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt oxide is used as positive electrode active material, then high energy density is achieved, but stability at high voltage and high temperature deteriorates
Solution Approach 1:
The patent applies composite materials by combining lithium cobalt oxide core particles with multiple coating layers (lithium titanium oxide, zirconium oxide, and spinel structure lithium cobalt-based oxide) to create a composite positive electrode active material. This composite structure maintains the high energy density of lithium cobalt oxide while the coating layers provide stability at high voltage and high temperature, preventing phase transitions and capacity degradation.
Solution Approach 2:
The patent applies local quality by creating different phases and compositions at different locations within the positive electrode active material. The core region contains lithium cobalt oxide for high energy density, while the surface regions contain coating layers with specific protective functions. The spinel structure lithium cobalt-based oxide phase is specifically formed at the surface to enhance stability, while the core maintains its layered structure for capacity.
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 composite material improves high-voltage and high-temperature characteristics, reducing side reactions and capacity fade, resulting in enhanced performance and lifespan of lithium secondary batteries.
Implementation Method 1
heat-treating the first precursor mixture to form a heat-treated first precursor mixture
Implementation Method 2
heat-treating the second precursor mixture, to thereby prepare the composite positive electrode active material
Data Source
AI summary
A composite positive electrode active material for a lithium secondary battery, the composite positive electrode active material including: a lithium cobalt oxide particle; and a particle coating portion in a form of an island and on a first surface of the lithium cobalt oxide particle, the particle coating portion including a first coating layer including a lithium titanium oxide, wherein the lithium cobalt oxide particle includes a lithium-deficient cobalt oxide phase positioned between the particle coating portion and a core of the lithium cobalt oxide particle, the lithium-deficient cobalt oxide phase having a molar ratio of lithium to cobalt of about 0.9 or less, and a surface coating portion located between a second surface of the lithium cobalt oxide particle and the core of the lithium cobalt oxide particle.