Core-Shell Lithium Metal Oxide for Battery Thermal Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges with thermal stability, capacity, and output characteristics due to limitations in existing positive electrode active materials such as LiCoO2, LiMnO2, and LiNiO2, which suffer from high temperature safety issues, resource constraints, and chemical instability.
Innovation Solution
A positive electrode active material with a core-shell structure is developed, comprising a core of lithium transition metal oxides including nickel, manganese, and cobalt, with a shell of lithium transition metal oxides and an inorganic material layer coating, enhancing structural stability and maintaining thermal stability while achieving high capacity and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-containing cobalt oxide (LiCoO2) is used as positive electrode active material, then charge/discharge efficiency and lifespan characteristics are improved, but high temperature safety is lowered and material cost increases
Solution Approach 1:
The positive electrode active material is divided into a core region containing LiCoO2 (providing excellent lifespan and charge/discharge efficiency) and a shell region containing lithium-containing manganese oxide (providing high temperature safety). This segmentation allows each material to be placed where it is most effective, resolving the contradiction between lifespan and thermal safety.
Solution Approach 2:
The invention creates a composite positive electrode active material combining LiCoO2 and lithium-containing manganese oxide in a core-shell structure. This composite approach leverages the strengths of both materials: LiCoO2 for reliability and manganese oxide for thermal stability, thereby achieving both long lifespan and high temperature safety simultaneously.
2Ease of manufacture
If lithium-containing manganese oxide (LiMnO2 or LiMn2O4) is used as positive electrode active material, then thermal stability and cost are improved, but capacity and high temperature characteristics are reduced
Solution Approach 1:
The positive electrode active material is segmented into a core region containing lithium-containing manganese oxide (providing thermal stability and cost advantages) and a shell region containing LiCoO2 (providing high capacity). This segmentation allows manganese oxide to provide its cost and thermal stability benefits while the Co-rich shell compensates for the low capacity issue.
Solution Approach 2:
The invention creates a composite material combining lithium-containing manganese oxide and LiCoO2, where the manganese oxide core provides cost-effectiveness and thermal stability, while the LiCoO2 shell provides high capacity, thereby resolving the contradiction between cost/thermal stability and capacity.
3Quantity of substance
If lithium-containing nickel oxide (LiNiO2) is used as positive electrode active material, then battery capacity is improved, but chemical stability is reduced causing phase transition and deterioration
Solution Approach 1:
The positive electrode active material is segmented into a core region containing lithium-containing nickel oxide (providing high discharging capacity) and a shell region containing LiCoO2 (providing chemical stability). This segmentation protects the Ni-rich core from direct exposure to electrolyte and atmosphere, preventing phase transitions and chemical deterioration while maintaining high capacity.
Solution Approach 2:
The invention creates a composite material where LiNiO2 and LiCoO2 are combined in a core-shell structure. The LiCoO2 shell acts as a protective layer that prevents chemical degradation of the LiNiO2 core, thereby maintaining both high capacity and chemical stability during cycling.
4Reliability
If metal-substituted nickel-based lithium-transition metal oxide is used as positive electrode active material, then cycle characteristics are improved, but thermal stability deteriorates due to low chemical stability
Solution Approach 1:
The positive electrode active material is segmented into a core region containing metal-substituted nickel-based lithium-transition metal oxide (providing improved cycle characteristics) and a shell region containing lithium-containing manganese oxide (providing thermal stability). This segmentation allows the Ni-based core to deliver good cycling performance while the Mn-rich shell ensures thermal safety.
Solution Approach 2:
The invention creates a composite material combining metal-substituted nickel-based lithium-transition metal oxide and lithium-containing manganese oxide. The composite structure allows the Ni-based component to provide cycle stability while the Mn-based component provides thermal stability, resolving the contradiction between these two properties.
Data Source
AI summary
The present invention provides a positive electrode active material for a lithium secondary battery having a core-shell structure which comprises: a core composed of lithium transition metal oxides including nickel(Ni), manganese(Mn) and cobalt(Co); and a shell composed of lithium transition metal oxides including cobalt(Co), wherein an inorganic material layer is further formed by coating on the surface of the shell.