Graphite Complex Particles for Solid-State Battery Anode Contact
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Solution Overview
Problem
The use of solid electrolytes in all-solid type batteries results in reduced electrochemical reaction sites and capacity due to insufficient contact between the active material and the electrolyte, leading to capacity and output reduction.
Innovation Solution
The development of complex particles comprising graphite particles coated with a mixture of a solid electrolyte and a conductive material, formed through a mechanical granulation process, which increases the contact area and maintains ion and electron conduction paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical graphite particles are used as negative electrode active material with solid electrolyte, then battery safety and reliability are improved, but contact area between electrolyte and active material is reduced, resulting in capacity and output reduction
Solution Approach 1:
The invention segments the spherical graphite particle into multiple domains: a core graphite region and multiple hollow cavities distributed throughout. This segmentation increases the internal surface area and creates numerous contact sites for the solid electrolyte, thereby improving ionic conductivity and battery capacity while maintaining the safety benefits of solid electrolyte usage.
Solution Approach 2:
The invention introduces a porous hollow cavity structure within the graphite particles. These cavities are filled with solid electrolyte material, creating extensive internal surfaces that enhance contact between the active material and electrolyte. This porous structure resolves the contradiction by providing both the safety of solid electrolyte and the capacity needed through increased reaction sites.
2Reliability
If spherical graphite particles are used as negative electrode active material with solid electrolyte, then battery safety is improved, but output is reduced
Solution Approach 1:
By segmenting the graphite particle into multiple cavities, the invention creates numerous parallel ionic conduction pathways. This segmentation reduces the distance for ion transport and increases the number of simultaneous electrochemical reactions, thereby improving power output while maintaining safety through solid electrolyte usage.
Solution Approach 2:
The porous hollow cavity structure provides extensive internal surfaces filled with solid electrolyte, creating multiple active reaction sites. This increases the overall reaction rate and power output while the solid electrolyte maintains battery safety, resolving the contradiction between safety and power performance.
3Reliability
If solid electrolyte is used instead of liquid electrolyte, then battery safety and energy density are improved, but ionic conductivity is reduced
Solution Approach 1:
The porous hollow cavity structure filled with solid electrolyte creates extensive internal surfaces and shortens ion transport distances. This porous architecture compensates for the inherently lower ionic conductivity of solid electrolytes by providing multiple parallel conduction pathways and reducing the length of ion diffusion paths, thereby maintaining acceptable ionic conductivity while preserving safety and energy density benefits.
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 complex particles enhance ionic conductivity and maintain high battery capacity and output by ensuring a dense electrode structure with minimal porosity, overcoming the limitations of conventional graphite-based electrodes.
Implementation Method 1
the lithium ionic conductivity of the solid electrolyte is lower than that of liquid electrolyte, but it is reported that, theoretically, ionic conductivity in a solid is higher than ionic conductivity in a liquid
Implementation Method 2
a mixture including a solid electrolyte and a conductive material fills gaps between the graphite materials of the graphite particles
Data Source
AI summary
Complex particles for a negative electrode active material according to the present disclosure have no problem with reduced capacity and output by virtue of sufficient electrochemical reaction sites between a solid electrolyte and an electrode active material. The complex particles according to the present disclosure include carbon particles of a carbon material such as flaky graphite, which are spherical in shape by shape modification, and a solid electrolyte and a conductive material filled between the particles, and thus have the increased contact area between the active material and the solid electrolyte increases, and ion conduction and electron conduction paths extended and maintained to the inside of the active material particles.