Lithium Cobalt Oxide Cathode Doping for Stable High-Delithiation Cycling
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Solution Overview
Problem
Existing lithium-ion batteries face challenges in energy density, safety, and cycling performance, particularly in the positive electrode material, which degrades during highly delithiated states.
Innovation Solution
A lithium cobalt oxide with a P63mc crystal structure is developed, incorporating specific peak height ratios in Raman spectra and doping with alkaline earth metals at Li sites to support the transition metal layer, enhancing structural stability and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt oxide is used as positive electrode material, then high specific energy and high working voltage are achieved, but cycling performance deteriorates due to structural degradation in highly delithiated state
Solution Approach 1:
The patent applies local quality by doping alkaline earth metal elements (Ca, Mg) specifically at Li sites within the lithium cobalt oxide crystal structure. This localized modification at specific crystallographic positions provides structural support exactly where needed during delithiation, maintaining the overall high energy density while improving local structural stability to enhance cycling performance
Solution Approach 2:
The patent creates a composite material system by incorporating alkaline earth metal elements into the lithium cobalt oxide matrix. This composite approach combines the high energy density characteristics of LiCoO2 with the structural stability provided by doped Ca or Mg atoms, achieving both high specific energy and improved cycling reliability
2Stability of the object's composition
If doping with alkaline earth metal element M is performed at Li sites, then structural stability in highly delithiated state is improved through pillar effect, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the doping concentration of alkaline earth metal elements within specific ranges (0.01≤x≤0.10 in formula Li1-xMxCoO2). This parameter optimization ensures sufficient structural support from the pillar effect while avoiding excessive complexity in synthesis and processing, achieving a balance between structural stability and manufacturing feasibility
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 proposed positive electrode material improves cycling stability and structural integrity, leading to better performance and longer service life of electrochemical and electric apparatuses.
Implementation Method 1
the element M doped into the Li sites can provide a pillar effect, which, in a highly delithiated state, can support the transition metal layer and reduce collapse of the transition metal layer
Implementation Method 2
In a Raman spectrum of the positive electrode material, a peak height of a characteristic peak within a range of 490 cm−1±5 cm−1 is I1, and a peak height of a characteristic peak within a range of 592 cm−1±5 cm−1 is I2
Data Source
AI summary
A positive electrode material includes a lithium cobalt oxide with a P63mc crystal structure. In a Raman spectrum of the positive electrode material, a peak height of a characteristic peak within a range of 490 cm−1±5 cm−1 is I1, and a peak height of a characteristic peak within a range of 592 cm−1±5 cm−1 is I2, satisfying 1<I2/I1<5.