Fine Graphite Negative Electrode for Lithium Ion Battery Cycle Life
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Solution Overview
Problem
Lithium ion secondary batteries with graphite-based negative electrodes require improved cycle characteristics to enhance their performance in energy storage applications.
Innovation Solution
A lithium ion secondary battery design incorporating a negative electrode composed of a fine graphite material, a conductive aid, and a binder, where the fine graphite material forms an electroconductive path between particles of the negative electrode active material, reducing disconnection and maintaining conductivity during charge/discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If graphite-based negative electrode active material is used to achieve high energy density, then energy density is improved, but cycle characteristics deteriorate
Solution Approach 1:
Fine graphite material particles with diameter of 0.1 μm to 10 μm are introduced as intermediary conductive components between negative electrode active material particles. These fine graphite particles form a conductive network that maintains electrical connectivity during charge/discharge cycles, preventing disconnection while preserving the high energy density benefits of graphite-based materials.
Solution Approach 2:
The negative electrode is constructed as a composite structure combining negative electrode active material particles (graphite or alloy) with fine graphite material particles. This composite configuration creates a dual-function system where the active material provides high capacity and the fine graphite provides structural conductivity, resolving the contradiction between energy density and cycle characteristics.
2Reliability
If fine graphite material is added to form electroconductive paths, then cycle characteristics are improved, but electrode structure complexity increases
Solution Approach 1:
Fine graphite material is selectively distributed in the interstitial spaces between negative electrode active material particles, creating local conductive pathways where needed. This localized approach maintains overall electrode simplicity while providing targeted conductivity enhancement at critical interfaces between active material particles.
Solution Approach 2:
The electrode structure utilizes the porous interstitial spaces between active material particles to accommodate fine graphite material. This porous configuration allows the fine graphite to form conductive networks without requiring additional structural components, maintaining electrode simplicity while improving cycle characteristics.
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 battery exhibits improved cycle characteristics, reduced resistance, and capacity retention, with the fine graphite material contributing to the formation and retention of electroconductive paths, preventing disconnection and enhancing overall battery performance.
Implementation Method 1
the fine graphite material forms an electroconductive path between particles of the negative electrode active material
Implementation Method 2
a negative electrode including a negative electrode active material of a carbon material capable of intercalating and deintercalating a lithium ion
Data Source
Figure 1(a)~1(b)
Figure 2
AI summary
A negative electrode for a lithium ion secondary battery, the negative electrode including a negative electrode active material, a fine graphite material, a conductive aid, and a binder, wherein the mass ratio of the fine graphite material to the conductive aid is in the range from 1 to 10, and the average particle diameter (median diameter D50) of the fine graphite material is smaller than the average particle diameter of the negative electrode active material, and in the range of 1 to 15 µm.