Solid-State Battery Graphite Void Electrolyte for Rate Capability
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Solution Overview
Problem
Conventional solid-state batteries face challenges in achieving improved rate characteristics due to the trade-off between electron conductivity and ion conductivity in the negative electrode layer, where increasing the amount of solid electrolyte decreases the volume proportion of graphite, reducing electron conductivity and preventing particle contact.
Innovation Solution
Incorporating a graphite particle with internal voids filled with solid electrolyte, forming a negative electrode active material that maintains high electron conductivity and efficient lithium ion insertion and desorption, with specific structural features such as void diameters and electrolyte composition to enhance ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more solid electrolyte is added to improve ion conductivity, then ion conductivity is improved, but capacity density is decreased
Solution Approach 1:
The solid electrolyte is locally concentrated in the shell region rather than being uniformly distributed throughout the electrode. This localized placement ensures sufficient ion conductivity at the electrode-electrolyte interface while minimizing the overall volume occupied by solid electrolyte, thereby preserving capacity density.
Solution Approach 2:
The shell region is designed with a porous or hollow structure that provides pathways for ion transport without requiring excessive solid electrolyte material. The porous structure increases the surface area for ion conduction while maintaining a compact overall volume.
2Stability of the object's composition
If graphite particles are combined with binders to form films, then film formation is improved, but ion conductivity is impaired
Solution Approach 1:
The invention creates a composite shell material that combines binder components for film formation with solid electrolyte components for ion conductivity. This composite structure achieves both mechanical integrity and ionic transport functionality simultaneously.
Solution Approach 2:
The shell region is designed with specific local properties that differ from the core: it contains binder materials optimized for film formation and adhesion, while also incorporating solid electrolyte for ion conductivity. This localized functional differentiation resolves the contradiction between film stability and ion transport.
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 proposed structure improves the rate characteristics of the solid-state battery by balancing electron and ion conductivity, allowing for efficient lithium ion transport and maintaining capacity density.
Implementation Method 1
a solid electrolyte being present in the void
Implementation Method 2
an electron conduction path formed of active material particles in contact with each other
Data Source
AI summary
A solid-state battery of the present disclosure includes: a negative electrode layer including a negative electrode active material; a positive electrode layer; a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer. The negative electrode active material includes: a graphite particle being an aggregate of a plurality of primary particles including graphite, the graphite particle having a void inside; and a solid electrolyte being present in the void. At least a portion of the void may be filled with the solid electrolyte. The void has a minimum diameter of, for example, 1 nm or more and 70 nm or less.