Cobalt-Stabilized Layered-Spinel Composite Cathode for Voltage Fade
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Solution Overview
Problem
State-of-the-art lithium batteries face limitations in energy capacity and efficiency due to voltage fade in 'layered-layered' electrode materials, which are inadequate for powering electric vehicles over acceptable driving ranges.
Innovation Solution
A composite lithium metal oxide electrode material with a 'layered-layered-spinel' structure, specifically formulated as y[xLi2MO3.(1−x)LiM′O2].(1−y)Li1+dMn2−z−dM″zO4, where M, M′, and M″ include metal ions like Mn, Ni, and Co, stabilizing the voltage profile and reducing voltage fade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If layered-layered composite cathode structures are used to enhance energy capacity, then the capacity increases significantly, but voltage fade occurs on repeated cycling which reduces energy output and efficiency
Solution Approach 1:
The patent applies composite materials by combining layered Li2MnO3 and LiMO2 components with a spinel LiMn2O4 component to form a layered-layered-spinel composite structure. This composite approach leverages the high capacity of layered materials while incorporating the voltage stability of spinel materials, thereby resolving the contradiction between achieving high energy capacity and maintaining voltage stability during cycling.
Solution Approach 2:
The patent applies local quality by creating distinct regions within the composite cathode structure where layered components provide high capacity in specific zones while spinel components provide voltage stability in other zones. The composite structure allows different materials to perform their specialized functions locally, with the layered portions contributing to capacity and the spinel portions contributing to voltage fade resistance.
2Ease of manufacture
If conventional cathode materials like layered LiMO2 are used, then the structure is simple and easy to manufacture, but they do not offer sufficient capacity or high enough electrochemical potential to meet energy demands
Solution Approach 1:
The patent resolves this contradiction by creating a composite cathode structure that combines multiple materials (layered Li2MnO3, layered LiMO2, and spinel LiMn2O4) to achieve high energy capacity while maintaining manufacturability. The composite approach allows the benefits of different materials to be combined without requiring entirely new manufacturing processes, thus preserving ease of manufacture while dramatically improving energy capacity.
Solution Approach 2:
The patent merges conventional cathode materials with spinel components to create a composite structure that achieves the high capacity and electrochemical potential needed for electric vehicles. By combining proven materials that can be manufactured with existing processes with additional functional components, the patent increases energy capacity while maintaining reasonable ease of manufacture.
3Power
If high capacity cathodes like xLi2MnO3.(1−x)LiMO2 are used to meet energy demands, then the energy output increases, but voltage fade on repeated cycling compromises cell operation management
Solution Approach 1:
The patent applies composite materials by integrating spinel LiMn2O4 components into the layered-layered cathode structure. The spinel component specifically addresses voltage fade issues during cycling while the layered components maintain high capacity. This composite structure enables the cathode to deliver high energy output with improved cycling stability, resolving the contradiction between power and reliability.
Solution Approach 2:
The patent applies parameter changes by modifying the cathode composition to include spinel phases with specific crystal structures and electrochemical properties. By changing the material parameters (compositional ratios, crystal structure types) in the composite, the patent achieves both high energy output and improved voltage stability during repeated cycling.
Data Source
AI summary
An electrode material comprising a composite lithium metal oxide, which in an initial state has the formula: y[xLi2MO3.(1−x)LiM′O2].(1−y)Li1+dMn2−z−dM″zO4; wherein 0≤x≤1; 0.75≤y<1; 0<z≤2; 0≤d≤0.2; and z−d≤2. M comprises one or more metal ions that together have an average oxidation state of +4; M′ comprises one or more metal ions that together have an average oxidation state of +3; and M″ comprises one or more metal ions that together with the Mn and any excess proportion of lithium, “d”, have a combined average oxidation state between +3.5 and +4. The Li1+dMn2−z−dM″zO4 component comprises a spinel structure, each of the Li2MO3 and the LiM′O2 components comprise layered structures, and at least one of M, M′, and M″ comprises Co. Cells and batteries comprising the electrode material also are described.