Cathode Active Material Composition for Stable Lithium Battery Lifespan
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving desired capacity and lifespan due to non-uniformity in the chemical structure of metal composite oxides, leading to structural distortions and reduced stability during charging and discharging.
Innovation Solution
A cathode active material comprising lithium-transition metal composite oxide particles with a controlled (113) plane FWHM change rate of 75% or less, measured through in-situ X-ray diffraction, which suppresses lattice and crystal structure distortions, reducing gas generation and enhancing lifespan characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-transition metal composite oxide is used as cathode active material, then high operating voltage and high energy density are achieved, but non-uniformity in chemical structure and crystal structure distortions occur leading to reduced lifespan and stability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the FWHM (Full Width at Half Maximum) of the (113) plane diffraction peak to be within 0.2-0.5 degrees. This parameter control ensures uniform crystal structure and minimizes structural distortions during charging-discharging cycles, thereby maintaining high energy density while improving lifespan stability and operational reliability
Solution Approach 2:
Instead of attempting to prevent capacity fade through electrolyte additives or surface coatings, the patent inverts the approach by controlling the intrinsic crystal structure uniformity of the cathode material itself. By ensuring uniform chemical composition and controlling the (113) plane FWHM, the material inherently resists structural degradation, eliminating the need for additional protective measures
2Productivity
If metal composite oxide structure is maintained during charging and discharging, then capacity retention is improved, but structural deformation and damage occur reducing life-span characteristics
Solution Approach 1:
The patent applies beforehand cushioning by pre-controlling the crystal structure uniformity through FWHM specification before the battery enters service. This structural pre-conditioning creates a buffer against mechanical stresses during charging-discharging cycles, preventing structural collapse and extending the duration the battery can maintain its 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 solution effectively improves the operational stability and lifespan of lithium secondary batteries by preventing crystal structure deformation and side reactions, resulting in reduced gas generation and improved capacity retention.
Implementation Method 1
lithium-transition metal composite oxide particles having a (113) plane FWHM (Full Width at Half Maximum) change rate of 75% or less, which is measured through in-situ X-ray diffraction (XRD)
Data Source
Figure 1~2
AI summary
Embodiments of the present invention provide a cathode active material for a lithium secondary battery including lithium-transition metal composite oxide particles. The lithium-transition metal composite oxide particles have a (113) plane FWHM change rate of 75% or less, which is measured through in-situ X-ray diffraction (XRD) and defined by Equation 1. Thereby, lifespan characteristics of the lithium secondary battery may be improved by preventing a lattice structure and/or a crystal structure in lithium-transition metal composite oxide particles from being deformed.