Natural Graphite Anode Particle Size Control for Lithium Battery
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Solution Overview
Problem
Conventional lithium secondary batteries using natural graphite as anode active material suffer from high electrode expansion ratios, leading to deteriorated life-time properties, while using artificial graphite does not improve power output and increases resistance, and high-density active material mixtures degrade life-time properties.
Innovation Solution
A lithium secondary battery design featuring an anode active material with natural graphite particles having an average diameter of 9 μm to 14 μm, a particle density change ratio of 0.06 or less, and a half value width in particle size distribution of 10 μm or less, along with a carbide coating to minimize pores and enhance packing, resulting in improved power and life-time properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as anode active material, then capacity is improved, but electrode expansion ratio increases and life-time property deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average particle diameter of natural graphite within 9-14 μm and the half value width of particle size distribution at 10 μm or less. This specific parameter optimization reduces electrode expansion ratio to 17% or less while maintaining high capacity, thereby improving both life-time property and capacity performance simultaneously.
2Reliability
If artificial graphite is used as anode active material, then life-time property is improved, but power output does not improve and resistance increases
Solution Approach 1:
The patent changes the particle size parameters of natural graphite (average diameter 9-14 μm, half value width ≤10 μm) to achieve optimal performance. This parameter optimization enables the anode to maintain low resistance and high power output while achieving improved life-time property, overcoming the limitations of artificial graphite.
3Quantity of substance
If high-density active material mixture is employed, then capacity is increased, but life-time property is degraded
Solution Approach 1:
The patent optimizes the particle size distribution parameters of natural graphite (average diameter 9-14 μm, half value width ≤10 μm) to achieve high capacity with improved life-time property. The controlled particle size enables better packing density and reduced expansion, allowing high-density active material mixture to maintain both high capacity and reliability.
Data Source
AI summary
A lithium secondary battery includes a cathode, an anode and a non-aqueous electrolyte. The anode includes an anode active material which includes a natural graphite, an average particle diameter (D50) of the natural graphite being in a range from 9 μm to 14 μm, and an expansion rate of the anode represented is 17% or less.