Lithium Composite Oxide Coating for Battery Stability
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Solution Overview
Problem
Existing battery technologies face challenges in maintaining high capacity retention and cycle stability due to cation mixing and electrolyte interactions, leading to inefficient lithium diffusion and structural instability at high potentials.
Innovation Solution
A positive electrode active material comprising a lithium composite oxide with a crystal structure belonging to space group Fd-3m and a covering material with low electron conductivity, which suppresses electron transfer and cation mixing, enhancing lithium diffusion and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium composite oxide is used as a positive electrode active material, then high capacity can be achieved, but capacity retention and cycle stability deteriorate due to cation mixing and electrolyte interactions
Solution Approach 1:
A covering material layer is introduced as an intermediary between the lithium composite oxide and the electrolyte. This covering material suppresses electron transfer and prevents direct contact between the electrolyte and the lithium composite oxide surface, thereby reducing side reactions and improving capacity retention while maintaining high capacity
Solution Approach 2:
The electron conductivity parameter of the covering material is controlled to be 10^-6 S/m or less. By changing the electrical property parameter of the covering material to be highly insulating, electron transfer is suppressed and cation mixing is prevented, thereby improving cycle stability without sacrificing capacity
2Power
If high potential is used to increase capacity, then energy density improves, but structural instability increases leading to poor cycle characteristics
Solution Approach 1:
The covering material serves as a protective intermediary that stabilizes the interface between the lithium composite oxide and the electrolyte at high potentials. This prevents structural degradation and maintains composition stability even when operating at high potentials for high energy density
Solution Approach 2:
By controlling the electron conductivity parameter of the covering material to be 10^-6 S/m or less, the system can operate at high potentials without suffering from structural instability. The low electron conductivity prevents electron transfer that would otherwise cause structural degradation at high potentials
3Reliability
If the covering material has low electron conductivity to suppress electron transfer, then cycle stability improves, but charge transfer efficiency may worsen
Solution Approach 1:
The covering material is applied as a thin surface layer only on the exterior surface of the lithium composite oxide particles. This localized application provides electron blocking where needed (at the particle surface) while leaving the bulk material's charge transfer properties intact, thus maintaining charge transfer efficiency while improving cycle stability
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 results in batteries with improved capacity retention and cycle stability, even at high potentials, by optimizing lithium diffusion paths and reducing side reactions, thereby extending battery life and maintaining high capacity.
Implementation Method 1
The covering material has an electron conductivity of 10^-6 S/m or less
Implementation Method 2
enhancing lithium diffusion and structural stability
Data Source
AI summary
A positive electrode active material contains a lithium composite oxide and a covering material. The lithium composite oxide has a crystal structure that belongs to space group Fd-3m. The ration I(111)/I(400) of a first integrated intensity I(111) of a first peak corresponding to a (111) plane to a second integrated intensity I(400) of a second peak corresponding to a (400) plane in an XRD pattern of the lithium composite oxide satisfies 0.05≤I(111)/I(400)≤0.90. The covering material has an electron conductivity of 106 S/m or less.