Graphitic Carbon Anode Material for Fast-Charge Battery Reliability
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Solution Overview
Problem
Existing lithium ion secondary batteries face challenges in achieving a balance between rapid charging, long-term reliability, and maintaining high input power with long life, particularly in the context of electric and hybrid vehicles, where existing graphite carbon materials for negative electrodes do not adequately address these requirements.
Innovation Solution
A graphitic carbon material for negative electrodes with specific properties, including a crystallite size Lc (002) of 35 nm to 150 nm, tap density of 0.90 g/cm3, and other parameters, is developed to enhance input characteristics, high-temperature storage characteristics, and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If particle size of negative electrode active material is reduced to increase lithium ion diffusion, then input characteristics improve, but specific surface area increases leading to more side reactions and reduced long-term reliability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size Lc(002) to 35-150 nm and tap density to 0.90 g/cm³ or more. This optimizes the balance between lithium ion diffusion (improved by smaller crystallite size) and side reactions (reduced by controlled specific surface area through tap density), resolving the contradiction between input characteristics and long-term reliability
Solution Approach 2:
The patent applies local quality by differentiating between particle size and crystallite size. The particle size is controlled to optimize overall structure, while the crystallite size Lc(002) is specifically controlled to 35-150 nm to enhance lithium ion diffusion pathways locally, improving input characteristics without proportionally increasing harmful surface area
2Reliability
If specific surface area is reduced to minimize side reactions, then long-term reliability improves, but lithium ion diffusion distance increases reducing input characteristics
Solution Approach 1:
The patent resolves this contradiction by changing the crystallite size parameter Lc(002) to 35-150 nm. This creates short diffusion pathways within crystallites (improving input characteristics) while the controlled tap density of 0.90 g/cm³ or more maintains appropriate specific surface area (preserving long-term reliability by minimizing side reactions)
3Speed
If crystallite size Lc(002) is reduced to enhance lithium ion diffusivity, then input characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a practical crystallite size range of Lc(002) = 35-150 nm with tap density ≥0.90 g/cm³, which balances lithium ion diffusivity improvement with manufacturability. This parameter range achieves enhanced performance while remaining feasible for industrial production, avoiding excessive manufacturing complexity
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 developed graphitic carbon material improves input characteristics, high-temperature storage, and cycle characteristics, supporting the performance of lithium ion secondary batteries in electric and hybrid vehicles by enhancing adhesion and suppressing binder absorption.
Implementation Method 1
increase the diffusion of lithium ions within the solid
Implementation Method 2
a crystallite size Lc (002) determined by X-ray diffraction
Data Source
AI summary
A graphitic carbon material for a negative electrode of a lithium ion secondary battery, in which a crystallite size Lc (002) determined by X-ray diffraction is from 35 nm to 150 nm, and a tap density is 0.90 g/cm3 or more.