Hollow NCM Cathode Particles for Low-Cobalt Battery Output
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Solution Overview
Problem
The increasing demand for nonaqueous electrolyte secondary batteries for decarbonization efforts, particularly for battery electric vehicles, poses a resource shortage concern for cobalt, and existing ternary active materials with reduced cobalt content suffer from insufficient output characteristics.
Innovation Solution
A nonaqueous electrolyte secondary battery design utilizing a lithium nickel cobalt manganese composite oxide with a molar ratio of Ni to all metal elements except Li ranging from 40% to 60% and Co from 15% to 25%, in the form of hollow particles with a BET specific surface area of 3.0 m2/g or more, combined with a nonaqueous electrolyte containing a carboxylate ester and lithium bis(oxalato)borate, to enhance output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt content in ternary active material is reduced to address resource shortage, then resource sustainability is improved, but output characteristics deteriorate
Solution Approach 1:
The patent changes the particle morphology parameter from solid to hollow structure, and optimizes the size parameter (average particle size 3-15 μm, shell thickness 0.5-5 μm). This parameter change increases the specific surface area significantly, allowing reduced cobalt content while maintaining output characteristics through enhanced surface reactivity and electrolyte contact.
Solution Approach 2:
The patent employs hollow particle structure with controlled porosity, creating internal void space that increases the effective surface area for electrochemical reactions. The hollow structure with shell portion and through holes provides porous characteristics that enhance electrolyte penetration and ion transport, compensating for reduced cobalt content by improving reaction efficiency per unit mass.
2Power
If hollow particle structure with large specific surface area is used to improve output characteristics, then power delivery is improved, but manufacturing complexity increases
Solution Approach 1:
The hollow particle structure is segmented into distinct components: shell portion, hollow portion, and through holes. This segmentation creates a complex internal structure that enhances performance while the modular nature of the hollow sphere geometry allows for relatively straightforward synthesis through known chemical methods, balancing complexity with manufacturability.
Solution Approach 2:
The patent employs spherical hollow particles with curved surfaces, which are geometrically simpler to manufacture than irregular complex shapes. The spherical symmetry simplifies the synthesis process while the hollow interior and through holes provide the necessary complexity for enhanced performance, achieving an optimal balance between structural complexity and manufacturing ease.
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
This configuration achieves excellent output characteristics for lithium ion secondary batteries while using a ternary active material with a small cobalt content, reducing resistance and enhancing discharge efficiency through the specific surface area and electrolyte composition.
Implementation Method 1
The lithium nickel cobalt manganese composite oxide has a BET specific surface area of 3.0 m2/g or more
Implementation Method 2
The nonaqueous electrolyte contains a nonaqueous solvent, an electrolyte salt, and lithium bis(oxalato)borate
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode active material layer containing a positive electrode active material. The positive electrode active material includes a lithium nickel cobalt manganese composite oxide. In the composite oxide, a molar ratio of Ni to all metal elements except for Li is 40 to 60 mol %, and a molar ratio of Co to all the metal elements except for Li is 15 to 25 mol %. The composite oxide is in a form of hollow particles each including a shell portion, a hollow portion, and a through hole penetrating the shell portion. The composite oxide has a BET specific surface area of 3.0 m2/g or more. The nonaqueous electrolyte contains an electrolyte salt, lithium bis(oxalato)borate, and a nonaqueous solvent that contains a carboxylate ester having 4 or less carbon atoms.