Composite Anode Active Material for Lithium Battery
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Solution Overview
Problem
High capacity silicon-based anode materials for lithium batteries face challenges due to volume expansion during lithium intercalation and deintercalation, leading to cracking, pulverization, and degraded charge and discharge characteristics, which hinder commercialization.
Innovation Solution
A composite anode active material comprising a metal particle, a carbon-based material, and a garnet-type lithium ion conductor, where the garnet-type lithium ion conductor is between 1 to 5 parts by weight, and the carbon-based material includes carbon nanotubes, graphene, or graphite, is used to suppress volume expansion and improve ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode materials are used to achieve high theoretical capacity, then the specific capacity increases to about 4,200 mAh/g, but the volume expansion reaches about 300% or greater during lithium intercalation and deintercalation
Solution Approach 1:
The silicon particle is enclosed within a hollow carbon sphere structure, creating a nested configuration where the active silicon material is protected inside a resilient carbon container. This nesting allows the silicon to expand and contract during lithium cycling without structural collapse, maintaining electrical contact while accommodating the 300% volume expansion.
Solution Approach 2:
The hollow carbon sphere acts as a flexible shell that can deform to accommodate silicon's volume changes. The carbon shell maintains structural integrity during expansion and contraction cycles, preventing pulverization while allowing the silicon interior to undergo necessary volume changes for high capacity operation.
2Quantity of substance
If high volume expansion is accommodated, then high theoretical capacity is achieved, but cracking and pulverization of the anode materials occur
Solution Approach 1:
The hollow carbon sphere provides a flexible protective shell that absorbs mechanical stress from volume expansion. This carbon shell prevents cracking and pulverization of the silicon particle during repeated charge-discharge cycles, maintaining structural integrity while enabling high capacity operation.
Solution Approach 2:
The invention creates a composite structure combining silicon and carbon materials, where each component contributes its advantageous properties. The silicon provides high theoretical capacity while the carbon shell provides mechanical strength and flexibility, creating a synergistic composite that overcomes the limitations of pure silicon.
3Stability of the object's composition
If volume expansion is suppressed, then structural stability is improved, but charge and discharge characteristics are degraded
Solution Approach 1:
The nested configuration allows the silicon particle to maintain structural stability within the hollow carbon sphere while still permitting controlled volume changes. This nesting enables the system to achieve both structural stability and good charge-discharge characteristics by accommodating expansion in a controlled manner.
Solution Approach 2:
The invention changes the structural parameters of the anode material by creating a hollow sphere configuration rather than using dense silicon. This parameter change allows the material to maintain stability while accommodating volume changes, resulting in improved charge and discharge characteristics compared to conventional silicon anodes.
4Ease of manufacture
If conventional anode materials are used, then manufacturing is simpler, but electrical short and continuous electrolyte decomposition occur due to cracking and pulverization
Solution Approach 1:
The hollow carbon sphere shell provides a protective barrier that prevents electrical shorting and electrolyte decomposition. This shell structure maintains electrical stability and prevents the harmful effects of cracking and pulverization, improving battery reliability while remaining compatible with conventional manufacturing processes.
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 composite anode active material enhances the initial charge and discharge efficiency, lifespan characteristics, and durability of lithium secondary batteries by stabilizing the structure and maintaining electrical contact, thereby improving the battery's overall performance.
Implementation Method 1
a garnet-type lithium ion conductor... improving the battery's overall performance
Implementation Method 2
the carbon-based material includes carbon nanotubes, graphene, or graphite, is used to suppress volume expansion and improve ionic conductivity
Implementation Method 3
is used to suppress volume expansion and improve ionic conductivity
Data Source
AI summary
A composite anode active material, the composite including: a metal particle; a carbon-containing material, and a garnet-type lithium ion conductor, wherein an amount of the garnet-type lithium ion conductor is greater than 1 part by weight and less than 5 parts by weight, based on 100 parts by weight of a total weight of the metal particle, the carbon-containing material, and the garnet-type lithium ion conductor.