Binder-Free Silicon Anode Layer for Lithium Battery
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Solution Overview
Problem
Silicon-based anode materials in lithium secondary batteries are prone to durability degradation due to volume changes during the charge/discharge process, which shortens the battery life.
Innovation Solution
An anode layer comprising a three-dimensional carbon structure with cavities and silicon particles disposed within, where the carbon structure includes graphene or reduced graphene oxide without a binder, allowing for volume expansion and contraction without affecting the overall anode layer's volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based materials are used as anode materials to increase energy density, then gravimetric energy density and volumetric energy density are improved, but the electrode material is damaged by internal stress caused by abrupt volume change during charge/discharge, shortening battery life
Solution Approach 1:
Silicon particles are nested inside the three-dimensional carbon structure's cavities. The carbon structure acts as a container that holds the silicon particles, allowing the silicon to expand and contract during charge/discharge cycles while maintaining structural integrity. This nesting approach prevents the silicon particles from damaging the electrode material while preserving the high energy density benefits.
Solution Approach 2:
The carbon structure is designed with a porous three-dimensional architecture containing multiple cavities. These cavities provide space for silicon particle volume changes during lithium insertion and extraction. The porous structure allows the silicon to expand into the cavities without generating damaging internal stress, thereby maintaining electrode integrity and extending battery life while utilizing silicon's high energy density.
2Use of energy by moving object
If silicon particles are used in the anode layer to increase energy density, then battery performance is improved, but volume change of silicon particles during charge/discharge causes durability degradation
Solution Approach 1:
The invention changes the physical parameters of the carbon structure, specifically creating a three-dimensional architecture with controlled cavity sizes and distributions. The cavities are designed with specific volume ratios (30%-70% of total cavity volume occupied by silicon particles) to accommodate silicon expansion. This parameter optimization allows the system to maintain durability while achieving high energy density.
Solution Approach 2:
The anode layer is constructed as a composite material system combining carbon and silicon. The carbon structure provides structural stability and durability, while the silicon particles provide high energy density. The composite structure allows the two materials to work synergistically, with the carbon matrix constraining the silicon particles and preventing durability degradation while maintaining the energy density benefits.
3Stability of the object's composition
If a binder is used in the anode layer to maintain structural integrity, then electrode stability is improved, but energy density is reduced due to the additional non-active material
Solution Approach 1:
The invention extracts and removes the binder component from the anode layer structure. Instead of using a binder to hold the electrode together, the three-dimensional carbon structure with its cavities provides both structural integrity and silicon containment. This extraction of the binder eliminates the non-active material that would otherwise reduce energy density, while the carbon structure's mechanical properties maintain electrode stability.
4Use of energy by moving object
If the volume of silicon particles is increased to maximize energy density, then gravimetric energy density is improved, but internal stress and electrode damage are exacerbated
Solution Approach 1:
The invention applies local quality by creating specific regions (cavities) within the carbon structure that are optimized for silicon particle accommodation. Each cavity is designed with appropriate size and volume ratio to contain silicon particles of specific sizes. This local optimization allows larger silicon particles to be used for high energy density while the localized cavity structure prevents excessive internal stress and electrode damage.
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 reduces durability degradation and enhances the energy density of lithium secondary batteries by accommodating silicon particle volume changes within the carbon structure, thereby improving battery life and performance.
Implementation Method 1
a three-dimensional carbon structure including a plurality of cavities without a binder, and a plurality of silicon particles disposed in the plurality of cavities
Implementation Method 2
heating the polyimide structure with the first and second heat-resistant members disposed thereat
Implementation Method 3
heating the polyimide structure to about 2800° C. to about 3200° C.
Implementation Method 4
heating the graphene oxide to reduce the graphene oxide to graphene to form a pre-carbon structure on the aluminum structure
Implementation Method 5
applying heat or a microwave to the pre-carbon structure and the carbon sheet
Implementation Method 6
applying heat or a microwave to the pre-carbon structure and the carbon sheet
Data Source
AI summary
Example embodiments relate to an anode layer of a lithium secondary battery. The anode layer includes a three-dimensional carbon structure and a plurality of silicon particles. The three-dimensional carbon structure includes a plurality of cavities without a binder, and the plurality of silicon particles are disposed in the plurality of cavities.