Amorphous Carbon Negative Electrode for Solid-State Batteries
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Solution Overview
Problem
All solid-state batteries using lithium metal as a negative electrode face issues with volume expansion, dendrite formation, and short-circuits, leading to poor power characteristics and cycle-life performance.
Innovation Solution
A negative active material composed of aggregated amorphous carbon with metal nanoparticles, such as Ag, Au, or Pt, is used, where the metal nanoparticles are melted and embedded within the carbon pores to enhance electrical conductivity and suppress physical movement during charging and discharging, improving cycle-life and power characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as a negative electrode to increase energy density, then battery capacity is improved, but volume expansion and dendrite formation occur leading to poor cycle-life and reliability
Solution Approach 1:
The patent uses a composite structure consisting of amorphous carbon material with embedded metal nanoparticles (such as Al, Si, Ge, Sn, or their alloys). This composite material combines the high capacity of lithium-alloying metals with the structural stability and conductivity of amorphous carbon, preventing dendrite formation while maintaining high battery capacity.
Solution Approach 2:
The patent employs amorphous carbon material with a porous structure that can accommodate volume changes during lithium insertion and extraction. The porous structure provides a buffer for expansion and contraction, preventing structural degradation and maintaining electrode integrity over many charge-discharge cycles.
2Quantity of substance
If lithium metal is used as a negative electrode, then battery capacity is improved, but dendrite formation causes short-circuits
Solution Approach 1:
The composite of amorphous carbon and metal nanoparticles creates a stable interface that prevents lithium dendrite formation. The metal nanoparticles are dispersed within the carbon matrix, providing uniform lithium distribution and preventing the concentration of stress that leads to dendrite growth and short-circuits.
Solution Approach 2:
The patent creates local regions of metal nanoparticles within the carbon matrix that have different properties from the bulk material. These localized regions facilitate lithium insertion while the surrounding carbon provides structural support and prevents harmful dendrite formation at critical interfaces.
3Reliability
If a negative electrode is prepared by deposition of lithium without using lithium metal, then safety is improved, but power characteristics deteriorate
Solution Approach 1:
The amorphous carbon-metal nanoparticle composite provides both safety and high power characteristics. The metal nanoparticles enable fast lithium insertion and extraction kinetics for high power output, while the carbon matrix ensures structural stability and prevents short-circuits, achieving both safety and performance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the negative electrode by using amorphous carbon with specific pore structures and metal nanoparticle compositions. This allows optimization of both safety (preventing short-circuits) and power characteristics (fast charge-discharge rates) simultaneously.
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 results in improved battery capacity, cycle-life, and power characteristics by maintaining a stable interface and preventing lithium deposition-related issues, such as short-circuits and side reactions.
Implementation Method 1
the metal nanoparticles are melted and embedded within the carbon pores
Implementation Method 2
maintaining a stable interface by preventing lithium deposition-related issues
Data Source
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AI summary
Disclosed is a negative active material for an all solid-state battery. The negative active material comprises an aggregated material of amorphous carbon having pores inside and in which primary particles are aggregated; and metal nanoparticles filled in the pores.