Cathode Active Material Composition for Stable High-Power Li-Ion Cells
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Solution Overview
Problem
Lithium secondary batteries face challenges with thermal and mechanical stability, leading to degraded life-span and operational reliability due to high-power compositions of lithium metal oxides, which result in gas generation and capacity retention issues during charging and discharging.
Innovation Solution
A lithium-transition metal composite oxide particle with controlled lattice strain and XRD peak intensity ratio is used as a cathode active material, manufactured through specific precursor reactions and calcination processes, to enhance particle strength and lithium diffusion, thereby improving operational stability and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power composition is designed in lithium metal oxide, then power and capacity are improved, but thermal and mechanical stability are degraded
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lattice strain (n ≤ 0.18) and XRD peak intensity ratio (I(110)/{I(110)+I(003)} ≤ 8.9%) of the lithium-transition metal composite oxide. These parameter optimizations enable the material to achieve both high power output and improved thermal-mechanical stability, resolving the contradiction between power enhancement and stability maintenance
Solution Approach 2:
The patent uses composite materials by designing a lithium-transition metal composite oxide containing multiple transition metals (Ni, Co, Mn) in specific ratios. This composite structure allows the material to combine the high capacity benefits of nickel with the stability contributions from cobalt and manganese, achieving both high power and improved stability simultaneously
2Power
If high-power composition is designed in lithium metal oxide, then power and capacity are improved, but life-span is degraded
Solution Approach 1:
The patent optimizes specific parameters including lattice strain (n ≤ 0.18) and crystal structure characteristics (XRD peak intensity ratio ≤ 8.9%) to simultaneously achieve high power output and extended battery life-span. This precise parameter control prevents structural degradation during cycling while maintaining high capacity
Solution Approach 2:
The patent employs a cost-effective lithium-transition metal composite oxide composition that provides long cycle life without requiring expensive alternative materials, achieving extended life-span through optimized material composition rather than using premium components
3Power
If high-power composition is designed in lithium metal oxide, then power and capacity are improved, but operational reliability is degraded
Solution Approach 1:
The patent controls critical parameters including lattice strain (n ≤ 0.18) and XRD peak intensity ratio (≤ 8.9%) to ensure operational reliability while maintaining high power output. These parameter optimizations prevent structural failures and ensure consistent performance under various operating conditions
4Duration of action of stationary object
If lattice strain is controlled to reduce particle cracking, then life-span is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific target ranges for lattice strain (n ≤ 0.18) and XRD peak intensity ratio (≤ 8.9%) that can be achieved through controlled calcination processes. These parameter specifications provide clear manufacturing targets that balance life-span improvement with achievable manufacturing precision
Solution Approach 2:
The patent applies preliminary action by controlling the lattice strain and crystal structure parameters during the manufacturing process itself, rather than attempting to correct defects afterward. The calcination process is designed to achieve the target lattice strain and XRD characteristics from the beginning, preventing particle cracking before it occurs
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 controlled lattice strain and XRD peak intensity ratio of the lithium-transition metal composite oxide particles reduce particle cracking, gas generation, and lithium diffusion distance, resulting in improved life-span, capacity retention, and output performance, even at high temperatures.
Implementation Method 1
A lattice strain (n) calculated by applying Williamson-Hall method defined by Equation 1 to XRD peaks measured through X-ray diffraction (XRD) analysis is 0.18 or less
Implementation Method 2
XRD peaks measured through X-ray diffraction (XRD) analysis
Implementation Method 3
β cos θ=η sin θ+λ/D where β represents full width at half maximum (FWHM) (rad) of the corresponding peak acquired through the XRD analysis, θ represents a diffraction angle (rad)
Implementation Method 4
manufactured through specific precursor reactions and calcination processes
Data Source
AI summary
A cathode active material for a lithium secondary battery includes a lithium-transition metal composite oxide particle having a lattice strain (η) of 0.18 or less, which is calculated by applying Williamson-Hall method defined by Equation 1 to XRD peaks measured through XRD analysis, and having an XRD peak intensity ratio of 8.9% or less, which is defined by Equation 2. By controlling the lattice strain and XRD peak intensity ratio of the lithium-transition metal composite oxide particle, a lithium secondary battery with improved life-span characteristics as well as output characteristics is provided.