Stable Cobalt (IV) Oxide via Core-Shell Aluminum Phosphate Coating
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Solution Overview
Problem
Current methods fail to produce a stable cobalt oxide with a +4 valence, limiting the development of cobalt oxide and composite materials.
Innovation Solution
A method involving the electrochemical lithium deintercalation of lithium cobalt oxide composites at specific voltages to form a cobalt oxide with a +4 valence, utilizing a core-shell structure with an aluminum phosphate layer to maintain stability and prevent reduction of cobalt ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to produce cobalt oxide, then the production process is simple, but a stable cobalt oxide with +4 valence cannot be formed
Solution Approach 1:
The patent applies preliminary action by first forming a lithium cobalt oxide composite with a core-shell structure before performing electrochemical lithium deintercalation. The aluminum phosphate layer is pre-formed on the surface of lithium cobalt oxide particles, creating a protected structure that enables subsequent formation of stable cobalt (IV) oxide with +4 valence that would otherwise be unstable through conventional direct oxidation methods.
Solution Approach 2:
The patent uses an aluminum phosphate layer as an intermediary substance that mediates between the lithium cobalt oxide core and the external environment. This intermediate layer protects the cobalt ions during electrochemical processing, enabling the formation and stabilization of cobalt oxide with +4 valence by preventing unwanted side reactions and maintaining structural integrity during the oxidation process.
2Reliability
If electrochemical lithium deintercalation is performed at high voltage to form cobalt (IV) oxide, then cobalt ions maintain +4 valence state, but the cobalt oxide becomes unstable and reduces to lower valence
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior (core) contains lithium cobalt oxide with cobalt ions in their original valence state, while the exterior (shell) consists of aluminum phosphate that provides protective qualities. This spatial differentiation allows the cobalt oxide to maintain +4 valence locally at the surface during electrochemical processing while the core provides structural support, and the aluminum phosphate shell prevents bulk reduction to lower valence states.
Solution Approach 2:
The patent uses composite materials by combining lithium cobalt oxide with aluminum phosphate to form a core-shell composite structure. This composite approach allows the material to exhibit properties of both components: the lithium cobalt oxide provides the cobalt ions that can achieve +4 valence, while the aluminum phosphate shell provides chemical and thermal stability, preventing reduction and enabling the composite to maintain the high-valence cobalt oxide state.
3Reliability
If aluminum phosphate layer is added to form core-shell structure, then cobalt oxide stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by performing the aluminum phosphate layer formation as a preparatory step before the main electrochemical lithium deintercalation process. The core-shell structure is established in advance, creating a stable framework that simplifies subsequent processing and ensures consistent results during the high-voltage electrochemical treatment that forms the cobalt (IV) oxide.
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 method successfully produces a stable cobalt (IV) oxide with improved chemical and thermal stability, enhancing the performance of lithium ion batteries by maintaining the cobalt ions in a +4 valence state during charge and discharge cycles.
Implementation Method 1
utilizing a core-shell structure with an aluminum phosphate layer to maintain stability and prevent reduction of cobalt ions
Implementation Method 2
A method involving the electrochemical lithium deintercalation of lithium cobalt oxide composites at specific voltages to form a cobalt oxide with a +4 valence
Data Source
AI summary
A cobalt oxide is disclosed and is represented by a chemical formula of Co1-yMyO2, wherein 0≦y≦0.9, and M is selected from the group consisting of alkali metal elements, alkaline-earth metal elements, Group-13 elements, Group-14 elements, transition metal elements, and rare-earth elements. A composite of cobalt oxide includes a cobalt oxide and an aluminum phosphate layer coated on a surface of the cobalt oxide.