Lithium Composite Oxyfluoride Coated Positive Electrode
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Solution Overview
Problem
Existing battery technologies face challenges in maintaining high cycle characteristics and safety due to side reactions between positive electrode materials and electrolytes, leading to capacity degradation and heat generation during charge-discharge cycles.
Innovation Solution
A positive electrode active material comprising a lithium composite oxide coated with a lithium composite oxyfluoride, which suppresses side reactions and enhances resistance to high voltage, thereby improving cycle characteristics and safety by forming a solid solution with the lithium composite oxide and controlling the mass percentage of the oxyfluoride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium composite oxide is used as positive electrode active material, then high capacity is achieved, but side reactions with electrolyte occur leading to capacity degradation and heat generation
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where lithium composite oxide particles are coated with lithium composite oxyfluoride. This composite structure combines the high capacity characteristics of lithium composite oxide with the protective and stable properties of lithium composite oxyfluoride, resolving the contradiction between achieving high capacity and maintaining reliable cycle characteristics.
Solution Approach 2:
The lithium composite oxyfluoride coating acts as an intermediary layer between the lithium composite oxide and the electrolyte. This intermediate layer suppresses direct side reactions between the oxide and electrolyte, thereby preventing capacity degradation and heat generation while maintaining the high capacity benefits of the oxide core.
2Quantity of substance
If lithium composite oxide is used as positive electrode active material, then high capacity is achieved, but heat generation occurs during charge-discharge cycles
Solution Approach 1:
The lithium composite oxyfluoride coating serves as a thermal management intermediary by suppressing exothermic side reactions between the lithium composite oxide and electrolyte. This intermediate layer reduces heat generation during charge-discharge cycles while preserving the high capacity characteristics of the oxide core.
Solution Approach 2:
The patent converts the potential harm of heat-generating side reactions into a benefit by using the lithium composite oxyfluoride coating to suppress these reactions. The coating transforms the interface between oxide and electrolyte from a heat-generating problematic zone into a protective barrier that enhances thermal safety.
3Reliability
If coating layer is added to suppress side reactions, then cycle characteristics improve, but device complexity increases
Solution Approach 1:
The patent uses composite materials with a core-shell structure where the coating is integrated as an inherent part of the particle morphology. This approach improves cycle characteristics through the protective lithium composite oxyfluoride layer while minimizing structural complexity by maintaining a simple spherical particle form factor.
Solution Approach 2:
The lithium composite oxyfluoride coating is applied locally on the surface of lithium composite oxide particles rather than requiring complex bulk modifications. This localized coating approach improves cycle characteristics at the particle surface level while keeping the overall device structure simple and manageable.
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 configuration results in batteries with improved capacity retention and safety by reducing side reactions and heat generation, maintaining high cycle performance even after multiple charge-discharge cycles.
Implementation Method 1
a lithium composite oxyfluoride (2) covers at least part of a surface of the lithium composite oxide (1)
Implementation Method 2
solid solution with the lithium composite oxide
Data Source
AI summary
A positive electrode active material contains a lithium composite oxide and a lithium composite oxyfluoride. The lithium composite oxyfluoride covers at least part of the surface of the lithium composite oxide. The lithium composite oxyfluoride is represented by a composition formula LiαMe2βOγFδ, where Me2 represents at least one selected from the group consisting of Mn, Co, Ni, Fe, Al, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ru, and W; and 1.0≤α≤2.1; 0.8≤β≤1.3; 1.5≤γ≤2.9; and 0.1≤δ≤1.5. The crystal structure of the lithium composite oxyfluoride belongs to space group Fm-3m.