Bimodal Graphite Negative Electrode Active Material for Quick Charging
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high-rate charging and quick charging characteristics, particularly at high loading conditions, due to lithium plating and poor diffusion characteristics, which lead to deterioration and reduced efficiency.
Innovation Solution
A negative electrode active material comprising bimodal distribution graphite particles with specific size ranges and orientation indices, optimized for improved lithium ion conduction and electrolyte infiltration, reducing charge transfer resistance and enhancing quick charging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the loading amount of electrode is increased to achieve high capacity, then energy density is improved, but lithium plating occurs on the surface and causes cell deterioration
Solution Approach 1:
The patent applies parameter changes by controlling the particle size distribution of graphite particles within specific ranges (D10: 3-8 μm, D50: 15-25 μm, D90: 30-50 μm) and adjusting the ratio of different particle sizes. This optimization of physical parameters reduces lithium plating while maintaining high loading amounts, thereby improving both capacity and reliability
Solution Approach 2:
The patent implements local quality by creating a multi-modal particle size distribution where different sized particles serve different functions: smaller particles fill gaps and provide uniform coverage, medium particles form the bulk structure, and larger particles provide structural framework. This localized optimization of particle functions reduces lithium accumulation at specific sites, preventing plating and cell deterioration
2Speed
If quick charging is performed to meet high-rate charging demand, then charging speed is improved, but lithium plating occurs and causes cell deterioration
Solution Approach 1:
The patent optimizes particle size parameters (D10: 3-8 μm, D50: 15-25 μm, D90: 30-50 μm) to enable fast ion transport while preventing lithium plating. The controlled size distribution ensures that even at high charging rates, lithium ions can diffuse efficiently throughout the electrode without accumulating on the surface, thus maintaining both charging speed and cell reliability
Solution Approach 2:
The patent applies dynamics by creating a dynamic particle size distribution system that adapts to different charging rates. The multi-modal distribution allows the electrode structure to efficiently accommodate varying ion fluxes, maintaining optimal performance during quick charging while preventing pathological lithium plating that would cause cell deterioration
3Quantity of substance
If electrode loading amount is increased, then capacity is improved, but lithium diffusion characteristics deteriorate due to accumulation of lithium on electrode surface
Solution Approach 1:
The patent implements local quality through a multi-modal particle size distribution where smaller particles (D10: 3-8 μm) provide uniform surface coverage and efficient ion access, medium particles (D50: 15-25 μm) form the bulk capacity structure, and larger particles (D90: 30-50 μm) provide structural framework. This localized functional differentiation ensures that lithium diffusion remains efficient even at high loading amounts, preventing surface accumulation and maintaining good diffusion 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 negative electrode active material enables high-rate and quick charging with reduced lithium dendrite formation, improving battery efficiency and lifespan by shortening lithium ion conduction paths and increasing electrolyte infiltration.
Implementation Method 1
lithium ions deintercalated from a positive electrode active material upon the first charging are intercalated into a negative electrode active material, such as carbon particles, and deintercalated again upon discharging
Implementation Method 2
the amount of lithium ions diffused into the electrode through the pores thereof
Data Source
Figure 1a
Figure 1b~1c
Figure 2~3
AI summary
The present disclosure relates to a negative electrode active material for an electrochemical device which has improved quick charging characteristics. The negative electrode active material includes two types of graphite particles having a different particle diameter and shows a bimodal distribution, wherein the ratio of particle diameter (D50) of the first graphite particles/particle diameter (D50) of the second graphite particles is larger than 1.7.