Graphite Anode Composition to Suppress Battery Swelling
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Solution Overview
Problem
Lithium secondary batteries face issues with operational stability due to side reactions between the anode active material and electrolyte, leading to swelling and reduced lifespan, which are not effectively addressed by existing anode materials.
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 specific orientation and irregularity indices, and a carbon coating to suppress side reactions and enhance packing efficiency, thereby improving operational stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anode materials are used, then the battery can operate, but side reactions occur between the anode active material and electrolyte causing swelling and reduced operational stability
Solution Approach 1:
A coating layer comprising amorphous carbon and/or crystalline graphite is applied to the surface of the anode active material particles. This coating acts as an intermediary barrier between the anode active material and the electrolyte, preventing direct contact and thus suppressing side reactions that cause swelling and operational instability.
Solution Approach 2:
The anode active material is formed as a composite structure combining multiple materials (e.g., silicon oxide, silicon carbide, and carbon). This composite approach allows the material to benefit from the high capacity of silicon-based materials while the carbon component provides structural stability and suppresses harmful side reactions with the electrolyte.
2Use of energy by moving object
If anode active material particles are used to increase capacity, then energy density improves, but swelling occurs during charging and discharging reducing lifespan
Solution Approach 1:
The particle diameter of the anode active material is controlled within a specific range (3 μm to 15 μm). By optimizing this parameter, the material achieves a balance between providing sufficient capacity (energy density) and minimizing swelling during charge-discharge cycles, thereby extending battery lifespan.
Solution Approach 2:
The use of composite anode materials combining silicon oxide, silicon carbide, and carbon allows the structure to accommodate volume changes during lithium insertion/extraction. The carbon matrix provides structural integrity that prevents excessive swelling, enabling high energy density while maintaining long cycle life.
3Ease of manufacture
If graphite particles are used in the anode, then cost-efficiency is improved, but operational stability needs enhancement
Solution Approach 1:
The patent uses composite anode materials that include carbon-based materials (graphite, amorphous carbon) combined with other compounds. This composite approach maintains cost-efficiency by utilizing abundant carbon resources while achieving improved operational stability through the synergistic effects of the composite structure.
Solution Approach 2:
Different regions of the anode structure have different compositions optimized for their specific functions. The core particles may use cost-effective materials while the surface coating provides enhanced stability. This local differentiation allows cost-efficiency in bulk materials while ensuring operational stability at the interface with electrolyte.
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.