Linked Conductive Anode Material for Silicon Volume Change
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Solution Overview
Problem
High-capacity negative electrode active materials in lithium secondary batteries face issues with electrical short circuits and performance degradation due to excessive volume change during charging and discharging, which existing methods like carbon coating and additional conductive materials fail to adequately address, leading to conductivity degradation and reduced capacity retention.
Innovation Solution
A negative electrode active material is developed with a conductive material, such as linear or planar conductive materials, attached to the surface of the active material core through an organic linker with a hydrophobic structure and polar functional group, ensuring stable electrical conductivity even during volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity materials such as silicon are used to replace carbon-based negative electrode active materials, then the capacity is improved, but the volume change during charging and discharging causes electrical short circuits and performance degradation
Solution Approach 1:
The conductive material is embedded within a three-dimensional network structure formed by conductive polymers, creating a nested configuration where the conductive material particles are surrounded and interconnected by the polymer matrix. This nested structure provides mechanical support to accommodate volume changes while maintaining continuous electrical pathways.
Solution Approach 2:
The conductive polymer forms a flexible three-dimensional network that envelops the conductive material particles, creating a flexible shell-like structure. This flexible network can dynamically adjust to the volume expansion and contraction of the high-capacity active material during charging and discharging cycles, preventing electrical short circuits while maintaining conductivity.
2Stability of the object's composition
If a carbon coating layer is formed on silicon-based particles to address volume change, then the structural stability is improved, but cracks are generated or porosity is reduced which reduces efficiency
Solution Approach 1:
The conductive polymer forms a porous three-dimensional network structure with interconnected voids and channels. This porous structure provides multiple pathways for lithium ion transport, maintaining high charging-discharging efficiency while the polymer matrix accommodates volume changes without generating cracks that would reduce structural stability.
Solution Approach 2:
The invention creates a composite structure combining conductive material particles, conductive polymers, and optionally additional conductive materials in a three-dimensional network. This composite architecture synergistically provides both structural stability to handle volume changes and maintained porosity for efficient ion transport, avoiding the crack formation issue of carbon coating layers.
3Reliability
If additional conductive materials are used to improve conductivity, then the electrical conductivity is improved, but aggregation of conductive materials occurs which degrades performance
Solution Approach 1:
The conductive polymer acts as an intermediary matrix that disperses and individually supports the conductive material particles. The polymer network prevents direct contact and aggregation between conductive material particles while maintaining continuous electrical pathways through the polymer itself, ensuring stable conductivity without aggregation-related performance degradation.
Solution Approach 2:
The conductive material is divided into discrete particles or fragments that are individually embedded within the conductive polymer network. This segmentation prevents aggregation by spatially separating the conductive material units while the polymer matrix ensures electrical connectivity between them, maintaining conductivity without the harmful effects of aggregation.
4Stability of the object's composition
If a polymer composite is provided on the carbon coating layer to control volume change, then the volume change control is improved, but the conductivity of the active material is degraded causing resistance to increase
Solution Approach 1:
The invention changes the key parameter of the polymer from conventional insulating binders to conductive polymers. This parameter change transforms the polymer's function from merely providing mechanical support and volume change control to simultaneously providing electrical conductivity. The conductive polymer matrix maintains electrical pathways while accommodating volume changes, preventing resistance increase that would occur with insulating polymer composites.
Solution Approach 2:
The invention creates a composite material system where conductive polymers are combined with conductive material particles to form a three-dimensional network. This composite structure synergistically provides both volume change control through the polymer matrix and maintained electrical conductivity through the combined conductive polymer and conductive material pathways, avoiding the resistance increase problem of using insulating polymer composites.
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
This solution provides improved stability and conductivity, enhancing the cycle lifetime characteristics and initial efficiency of the battery by maintaining a stable electrical network and preventing disconnection due to volume changes in the active material.
Implementation Method 1
a conductive material that is attached to a surface of the active material core through an organic linker
Implementation Method 2
maintaining a stable electrical network and preventing disconnection due to volume changes in the active material
Data Source
AI summary
A negative electrode active material that includes an active material core that allows the intercalation and deintercalation of lithium ions; and a conductive material that is attached to a surface of the active material core through an organic linker. The conductive material includes at least one selected from the group consisting of a linear conductive material and a planar conductive material. The organic linker is a compound that includes a hydrophobic structure and a substituent including a polar functional group.