Soft-Carbon-Coated Graphite Anode for Stable Rolled Electrode Porosity
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high-temperature storage performance due to structural and internal pore volume changes during electrode rolling, particularly in rapid charging applications.
Innovation Solution
A negative electrode active material composed of artificial graphite coated with soft carbon in specific weight percentages (3-5 wt%) is used, controlling total pore volume variation to minimize structural changes and enhance high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If artificial graphite is used as negative electrode active material, then lifespan characteristics are improved due to stable crystal structure, but high-temperature storage performance deteriorates due to structural changes during electrode rolling
Solution Approach 1:
The patent uses a composite material system consisting of artificial graphite particles coated with soft carbon material. This composite structure combines the stable crystal structure of artificial graphite (which provides long lifespan) with the structural flexibility of soft carbon coating (which minimizes pore volume changes during rolling). The soft carbon coating acts as a buffer layer that accommodates structural changes during electrode manufacturing processes, thereby maintaining high-temperature storage performance while preserving the lifespan benefits of artificial graphite.
2Reliability
If soft carbon coating amount is increased to minimize pore volume changes, then high-temperature storage performance is improved, but charging and discharging rates deteriorate due to increased resistance
Solution Approach 1:
The patent optimizes the soft carbon coating amount to a specific parameter range (3-7 wt% based on total negative electrode active material weight). This parameter optimization balances two competing requirements: sufficient coating to minimize pore volume changes and improve high-temperature storage performance, versus limiting coating thickness to maintain good charging and discharging rates. The specified weight percentage range represents the optimal balance point where the soft carbon coating provides structural stability without creating excessive resistance.
3Productivity
If internal total pore volume is high after electrode rolling, then rapid charging capability is improved due to better ion transport, but high-temperature storage performance deteriorates
Solution Approach 1:
The patent applies local quality modification by coating only the surface of artificial graphite particles with soft carbon material, rather than changing the bulk properties of the entire electrode structure. The soft carbon coating is localized on the particle surfaces where it directly contacts the electrolyte and facilitates lithium ion transport. This localized modification improves high-temperature storage performance by minimizing structural changes during rolling, while the porous structure of the coating and underlying artificial graphite maintains adequate pore volume for rapid charging capability.
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 solution effectively improves high-temperature storage performance and rapid charging capabilities by maintaining minimal structural and pore volume changes during electrode rolling, as demonstrated by reduced pore resistance and increased energy density.
Implementation Method 1
a carbon-based negative electrode active material used for a negative electrode of a lithium secondary battery has a potential close to an electrode potential of lithium metal and has a small change in a crystal structure during intercalation and deintercalation of lithium ions
Implementation Method 2
the negative electrode active material has a total pore volume variation of 10 cm3/g or less before and after being rolled
Data Source
AI summary
A negative electrode active material for a lithium secondary battery, a negative electrode including the same, and a lithium secondary battery including the negative electrode. Specifically, the present invention relates to a negative electrode active material capable of minimizing changes in a structure and internal total pore volume of an electrode during rolling of the electrode by controlling the type and amount of carbon coated on a surface of an artificial graphite active material, a negative electrode including the same, and a lithium secondary battery including the negative electrode.