Doped Lithium Cobalt Oxide for High Voltage Stability
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Solution Overview
Problem
Lithium cobalt oxide-based positive electrode active materials in lithium secondary batteries suffer from poor thermal and structural stability at high voltages, limiting their use in applications like electric vehicles due to unstable crystal structures and high costs.
Innovation Solution
Doping lithium cobalt oxide with specific combinations of metallic and halide elements, represented by Formula Li(Co1-x-y-zM1xM2yM3z)O2-aHa, where M1, M2, and M3 are selected metallic elements and H is a halogen, to enhance structural stability and thermal properties, allowing stable operation at high voltages of 4.5 V or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium cobalt oxide is used as positive electrode active material, then high operating voltage and excellent capacity characteristics are achieved, but thermal properties deteriorate due to unstable crystal structure
Solution Approach 1:
The patent applies parameter changes by doping lithium cobalt oxide with specific elements (magnesium, calcium, strontium, barium, zinc, aluminum, gallium, indium, titanium, zirconium, hafnium) at controlled concentrations to modify the crystal structure parameters and electronic properties, thereby improving thermal stability while maintaining high operating voltage
Solution Approach 2:
The patent creates composite materials by combining lithium cobalt oxide with dopant elements to form doped lithium cobalt oxide compounds. These composite structures integrate the high voltage characteristics of LiCoO2 with the stabilizing effects of dopant elements, achieving both high power and improved reliability
2Quantity of substance
If lithium cobalt oxide is used as positive electrode active material, then excellent capacity characteristics are achieved, but structural stability deteriorates due to delithiation
Solution Approach 1:
The patent modifies the crystal structure parameters of lithium cobalt oxide through element doping, changing the lattice constants and electronic configuration to enhance structural stability during lithium extraction and insertion cycles, thereby maintaining capacity while improving stability
3Power
If lithium cobalt oxide is used as positive electrode active material, then high operating voltage is achieved, but cost increases
Solution Approach 1:
The patent optimizes the dopant concentration parameters to achieve effective performance improvement at low doping levels (typically 0.1-5 atomic percent), minimizing the amount of expensive dopant materials required while maintaining high operating voltage characteristics
Solution Approach 2:
The patent applies local quality by concentrating dopant elements at specific crystallographic sites within the lithium cobalt oxide structure where they provide maximum stabilizing effect, thereby reducing the overall dopant content needed and lowering material costs
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 doped lithium cobalt oxide exhibits improved structural stability and life characteristics, enabling lithium secondary batteries to maintain high capacity and durability at elevated voltages, thereby addressing the limitations of conventional lithium cobalt oxide materials.
Implementation Method 1
a lithium cobalt oxide is doped with a doping element including a metallic element and a halide element
Implementation Method 2
a positive electrode active material in which a lithium cobalt oxide is doped with a doping element including a metallic element and a halide element
Data Source
AI summary
In one embodiment, the present disclosure relates to a positive electrode active material in which a lithium cobalt oxide is doped with a doping element including a metallic element and a halide element, wherein the positive electrode active material is represented by Formula 1 and satisfies Equation 1, and a positive electrode for a lithium secondary battery and a lithium secondary battery, either of which include the positive electrode active material:Li(Co1-x-y-zM1xM2yM3z)O2-aHa [Formula 1](2x+3y+4z−a)/(x+y+z+a)<2.5. [Equation 1]