Lithium Battery Negative Electrode Orientation for High-Rate Cycle Life
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving improved electrochemical characteristics, particularly in terms of high-rate cycle-life and energy density, due to limitations in the orientation and conductivity of the negative active material.
Innovation Solution
A negative electrode for rechargeable lithium batteries is designed with a carbon-based negative active material and a conductive agent, where the conductive agent includes fiber-shaped or particle-shaped components with specific size and DD value ranges, optimizing the orientation and conductivity of the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbon-based negative active materials are used without specific orientation control, then the electrode structure is simple to manufacture, but the high-rate cycle-life and electrochemical performance are insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the orientation of graphite crystallites through specific processing parameters. The (004) plane orientation angle is controlled to be within 15° from the normal direction of the current collector surface, and the I(110)/I(004) intensity ratio is maintained within 0.05-0.5. These parameter controls improve high-rate cycle-life by optimizing lithium ion diffusion paths while maintaining manufacturability.
Solution Approach 2:
The patent uses composite materials by combining oriented artificial graphite crystallites with conductive agents and binders in a specific matrix structure. This composite approach maintains structural simplicity for manufacturing while achieving improved electrochemical performance through the synergistic effect of oriented graphite and conductive components.
2Reliability
If graphite materials are oriented with (004) plane at 45°-90° to current collector surface as in prior art, then conductivity is improved, but energy density and cycle-life performance are not sufficiently enhanced
Solution Approach 1:
The patent changes the orientation parameter from the prior art's 45°-90° range to a more specific 0°-15° range from the normal direction (i.e., 75°-90° from the surface). This parameter optimization, combined with controlling the I(110)/I(004) ratio within 0.05-0.5, achieves superior cycle-life performance while managing orientation control requirements through standardized processing.
3Ease of manufacture
If non-oriented carbon-based negative active material is used, then manufacturing process is simple, but internal resistance is high and electrochemical characteristics are poor
Solution Approach 1:
The patent introduces orientation parameters (I(110)/I(004) ratio of 0.05-0.5 and (004) plane angle of 15° from normal) that can be controlled through standard coating and drying processes. This maintains ease of manufacture while dramatically improving electrochemical characteristics including lower internal resistance and better charge-discharge performance.
4Quantity of substance
If high capacity non-carbon-based negative active materials like silicon or tin are used, then energy density is improved, but electrode expansion occurs during charge and discharge
Solution Approach 1:
The patent creates a composite structure where oriented artificial graphite crystallites form a stable matrix that can accommodate high capacity materials. The specific orientation control creates a structurally stable framework that prevents electrode expansion while allowing the incorporation of silicon or tin for enhanced energy density.
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 optimized negative electrode structure enhances the electrochemical performance by improving the high-rate cycle-life and energy density of the rechargeable lithium batteries, while also reducing internal resistance and suppressing electrode expansion during charge and discharge.
Implementation Method 1
a negative electrode for a rechargeable lithium battery including a current collector and a negative active material layer disposed on the current collector and including a carbon-based negative active material and a conductive agent
Implementation Method 2
a lithium-transition metal oxide having a structure capable of intercalating lithium ions
Implementation Method 3
a lithium-transition metal oxide having a structure capable of intercalating lithium ions
Data Source
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AI summary
Disclosed are a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same. The negative electrode for a rechargeable lithium battery includes a current collector and a negative active material layer disposed on the current collector and including a carbon-based negative active material and a conductive agent, wherein the conductive agent includes a fiber-shaped conductive agent having a length of about 1 µm to about 200 µm or a particle-shaped conductive agent having a size (long diameter) of about 1 µm to about 20 µm, and a DD (Degree of Divergence) value defined by Equation 1 is greater than or equal to about 24. DDDegree of Divergence=Ia/Itotal*100 In Equation 1, Ia is a sum of peak intensities at non-planar angles measured by XRD using a CuKα ray, Itotal is a sum of peak intensity at all angles measured by XRD using a CuKα ray.