Silicon Electrode Composite Structure for Stable Dry-Process Conductivity
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Solution Overview
Problem
The use of a dry manufacturing method for electrodes with silicon-based active materials results in reduced charge and discharge efficiency due to the conductive path being cut off and the active material becoming isolated during expansion and contraction.
Innovation Solution
An active material-conductive agent composite is formed with a conductive agent bound to the surface of spherical silicon-based particles using a first binder, and a fibril-shaped second binder is used to maintain connectivity, along with a conductive adhesive layer and a third binder to secure the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry manufacturing method is used for electrodes with silicon-based active materials, then environmental load is reduced and manufacturing efficiency is improved, but charge and discharge efficiency is significantly reduced due to conductive path cutoff
Solution Approach 1:
The conductive agent is pre-bound to the surface of spherical active material particles using a first binder before electrode assembly. This preliminary action ensures that conductive paths are established in advance, preventing isolation of active material during subsequent expansion and contraction cycles in the dry-manufactured electrode
Solution Approach 2:
A first binder acts as an intermediary substance to bind the conductive agent to the surface of the active material particles. This intermediary ensures stable attachment of the conductive agent, maintaining conductive paths even when the active material undergoes volume changes during charge and discharge
2Quantity of substance
If silicon-based active material is used to increase capacity, then energy density is improved, but volume change during charge and discharge causes conductive path disruption
Solution Approach 1:
The conductive agent is specifically positioned on the surface of the spherical active material particles, creating a local conductive network. This localized conductive layer maintains electrical connectivity at the particle surface even when the bulk active material undergoes volume changes during lithium intercalation and deintercalation
Solution Approach 2:
A composite structure is formed by combining the silicon-based active material with a surface-bound conductive agent layer. This composite material structure ensures that the high-capacity silicon maintains stable electrical contact throughout volume changes, preventing conductive path disruption while preserving high energy density
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
Maintains high charge/discharge efficiency of rechargeable batteries by preventing isolation of the active material during volume changes, enhancing the electrode's stability and conductivity.
Implementation Method 1
a first binder that binds the active material and the conductive agent
Implementation Method 2
the conductive agent is bound to a surface of the active material so as to elongate in a diametric direction of the active material
Implementation Method 3
an active material capable of intercalating and deintercalating lithium
Data Source
Figure 1
AI summary
Examples of the present disclosure maintain high charge/discharge efficiency of a rechargeable battery including an electrode including an active material such as a silicon-based active material, and manufactured by a dry method. Examples of the present disclosure include an active material-conductive agent composite including an active material capable of intercalating and deintercalating lithium, a conductive agent, and a first binder that binds the active material and the conductive agent. The active material is in the form of spherical particles, and the conductive agent is bound to a surface of the active material so as to extend in the radial direction of the active material by the first binder.