Graphite Composite Anode Structure for Low-Swelling Li-Ion Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges with operational stability due to side reactions between anode active materials and electrolytes, leading to swelling and reduced lifespan, particularly in applications requiring high energy density and cost-efficiency.
Innovation Solution
An anode for lithium secondary batteries is developed using a combination of artificial graphite with a single particle structure and natural graphite, optimized with an orientation index of 15 or less, irregularity degree between 1.7 and 2.2, and a carbon coating, which suppresses side reactions and enhances packing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional anode active materials are used, then high energy density is achieved, but side reactions with electrolyte cause swelling and reduced operational stability
Solution Approach 1:
The patent uses a composite anode active material consisting of artificial graphite and natural graphite in a weight ratio of 9:1 to 4:6. This composite structure combines the high energy density of artificial graphite with the operational stability of natural graphite, reducing side reactions with electrolyte while maintaining high capacity. The mixed graphite system suppresses swelling and improves lifespan without sacrificing energy density.
2Quantity of substance
If artificial graphite with high crystallinity is used, then capacity is improved, but orientation leads to swelling during charging and discharging
Solution Approach 1:
The patent applies local quality by combining highly crystalline artificial graphite particles (providing high capacity) with natural graphite particles (providing dimensional stability) in a specific spatial distribution within the anode active material layer. The natural graphite acts as a buffer that compensates for the swelling tendency of artificial graphite during lithium insertion/extraction cycles, maintaining overall structural stability while preserving high capacity.
3Device complexity
If single particle artificial graphite is used, then manufacturing complexity is reduced, but packing efficiency needs optimization
Solution Approach 1:
The patent optimizes the irregularity degree parameter of artificial graphite particles to a specific range (1.7 ≤ irregularity degree < 2.3) to balance manufacturing simplicity with packing efficiency. This parameter control ensures that single particle artificial graphite maintains good flowability and filling characteristics during manufacturing while achieving high packing density in the anode structure, eliminating the need for complex secondary particle structures.
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 improves the operational stability and lifespan of lithium secondary batteries by reducing swelling and maintaining high capacity retention, suitable for eco-friendly vehicles and renewable energy applications.
Implementation Method 1
an anode active material layer formed on at least one surface of the anode current collector... an anode active material that includes a natural graphite and an artificial graphite
Data Source
AI summary
An anode active material for a secondary battery according to an embodiment of the present disclosure includes an anode current collector, and an anode active material layer on at least one surface of the anode current collector. The anode active material layer includes an anode active material that includes a natural graphite and an artificial graphite. The artificial graphite has a form of single particles. An orientation index expressed as I(004)/I(110) is 15 or less.