Carbon Anode Composition for High-Density Li-Ion Electrodes
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Solution Overview
Problem
Conventional lithium-ion secondary battery negative electrodes face challenges in achieving high density and maintaining performance due to material hardness and deformation issues during pressing, leading to poor initial efficiency, rate characteristics, and capacity retention after high-temperature storage.
Innovation Solution
A carbon material composition comprising a carbon material with a specific pore structure and an organic compound-coated carbon material, which allows for flexible deformation and improved electrolyte immersion, preventing particle destruction and side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon material without organic compound coating is used, then hardness is high, but particle destruction occurs during pressing leading to poor initial efficiency and rate characteristics
Solution Approach 1:
An organic compound coating layer is introduced as an intermediary between the carbon material particles and the pressing force. This coating layer acts as a buffer that prevents direct mechanical contact and damage to the carbon particles during electrode fabrication, thereby maintaining particle integrity and ensuring good initial efficiency and rate characteristics.
Solution Approach 2:
The surface properties of the carbon material are changed by applying an organic compound coating. This modifies the mechanical and chemical parameters of the particle surface, making it more resistant to crushing during pressing while also improving electrolyte wettability and Li ion insertion/extraction kinetics.
2Quantity of substance
If carbon material with high pore volume is used, then electrolyte immersion is improved, but particle deformation occurs during pressing blocking electrolyte flow paths
Solution Approach 1:
The organic compound coating serves as a protective intermediary that maintains the porous structure of carbon particles during pressing. It prevents the collapse of pores and deformation of particle shapes by absorbing mechanical stress, thereby keeping electrolyte flow paths open while still allowing sufficient electrolyte immersion for good electrochemical performance.
3Volume of stationary object
If pressing pressure is increased to increase density, then negative electrode plate density increases, but particle destruction occurs creating active new surfaces
Solution Approach 1:
The organic compound coating acts as a protective layer that enables the application of high pressing pressure to achieve high electrode density without causing particle destruction. By distributing the mechanical stress uniformly, the coating prevents the formation of new active surfaces that would otherwise result from particle crushing, thereby maintaining good initial efficiency.
4Ease of manufacture
If carbon material is used without organic compound coating, then manufacturing simplicity is maintained, but side reactions occur reducing remaining capacity retention rate
Solution Approach 1:
The organic compound coating serves as a protective intermediary between the carbon material and the electrolyte. This coating layer suppresses unwanted side reactions such as electrolyte decomposition and gas generation at the carbon surface, thereby improving remaining capacity retention rate after high-temperature storage while adding only a simple coating step to the manufacturing process.
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 carbon material composition enables the production of high-density negative electrodes with enhanced initial efficiency, rate characteristics, and capacity retention after high-temperature storage, addressing the limitations of existing materials.
Implementation Method 1
the organic compound-coated carbon material (B)... prevents particle destruction and side reactions
Implementation Method 2
having a cumulative pore volume in a range of pore diameters of 0.01 μm or more and 1 μm or less of 0.02 mL/g or more... good electrolyte immersion
Data Source
AI summary
A carbon material composition may easily increase a density of a negative electrode plate and provide a secondary battery that is excellent in all of an initial efficiency, rate characteristics, and remaining capacity retention rate after high-temperature storage, and as a result, to provide a high-performance secondary battery. Such a carbon material composition may include a carbon material (A) and a carbon material (B), wherein the carbon material (A) has a cumulative pore volume of 0.02 mL/g or more in a range of pore diameters of 0.01 μm or more and 1 μm or less, and a ratio of a pore diameter to a volume-based average particle diameter, PD/d50 (%), expressed by formula (1) of 1.8 or less:PD/d50(%)=([mode pore diameter (PD) in a range of pore diameters of 0.01 μm or more and 1 μm or less in a pore distribution obtained by a mercury intrusion porosimetry]/[volume-based average particle diameter (d50)])×100, and(1)the carbon material (B) is an organic compound-coated carbon material.