All-solid-state battery electrode conductivity via crystalline carbon
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Solution Overview
Problem
All-solid-state batteries with solid electrolytes face challenges in achieving high discharge capacity and low internal resistance, particularly when using Li3V2(PO4)3 as an active material, due to lower electron conductivity compared to LiCoO2.
Innovation Solution
Incorporating carbon particles with a G-band full-width at half-maximum (G-FWHM) of 40 (m−1) or less in the positive and negative electrode active material layers, which enhances electron conductivity and reduces internal resistance by improving crystallinity and heat stability, allowing for high-density electrode formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Li3V2(PO4)3 is used as an active material in an all-solid-state battery, then the battery can achieve a 2 V class voltage with multiple oxidation-reduction potentials, but the electron conductivity becomes lower and the internal resistance becomes higher compared to LiCoO2
Solution Approach 1:
The patent changes the physical and chemical parameters of carbon particles by controlling their crystallinity (G-band FWHM ≤ 40 m−1) and particle size (D10 ≥ 0.1 μm, D90 ≤ 5.0 μm). These parameter changes enable the carbon particles to provide effective electron conduction pathways while maintaining structural stability during battery operation, thereby improving electron conductivity without sacrificing the voltage characteristics of Li3V2(PO4)3
Solution Approach 2:
The patent creates a composite structure by incorporating specific carbon particles into the Li3V2(PO4)3 active material matrix. This composite approach combines the high voltage characteristics of Li3V2(PO4)3 with the high electron conductivity of crystalline carbon particles, achieving both improved power and reliability simultaneously
2Reliability
If conventional carbon materials are used to improve electron conductivity, then a larger amount must be added, but this reduces the density of active material in the electrode
Solution Approach 1:
The patent dramatically improves the effectiveness of carbon additives by changing their crystallinity parameters (G-band FWHM ≤ 40 m−1). This parameter change allows carbon particles to provide superior electron conduction pathways at much lower concentrations (0.1-10 wt%), thereby maintaining high active material density while achieving the required electron conductivity
Solution Approach 2:
The highly crystalline carbon particles serve multiple functions simultaneously: they provide electron conduction pathways, maintain structural integrity during volume changes, and facilitate active material utilization. This self-service capability means that a small amount of carbon particles can achieve multiple objectives, preventing the need for large additions that would displace active material
3Productivity
If the discharge capacity is increased in all-solid-state batteries, then the internal resistance generally remains high due to the nature of solid electrolytes and active materials
Solution Approach 1:
The patent changes the particle size parameters of carbon (D10 ≥ 0.1 μm, D90 ≤ 5.0 μm) to optimize the balance between surface area for reactions and internal conduction pathways. This parameter optimization enables high discharge capacity by ensuring sufficient active material exposure while maintaining low internal resistance through effective carbon network formation
Solution Approach 2:
The patent introduces carbon particles as an intermediary substance that mediates between the solid electrolyte and the Li3V2(PO4)3 active material. This intermediary provides efficient electron conduction pathways that bridge the inherently high-resistance solid-state interface, enabling both high discharge capacity and low internal resistance to coexist
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 use of carbon particles with specific properties in the electrode layers increases electron conductivity, reduces internal resistance, and maintains a high discharge capacity while preventing excessive active material reduction.
Implementation Method 1
carbon particles in which a G-band full-width at half-maximum (G-FWHM) in a Raman spectrum is 40 (m−1) or less
Data Source
AI summary
An all-solid-state battery including: a positive electrode layer that has a positive electrode current collector layer and a positive electrode active material layer; a negative electrode layer that has a negative electrode current collector layer and a negative electrode active material layer; and a solid electrolyte layer that contains a solid electrolyte, in which the positive electrode active material layer and the negative electrode active material layer each have a G-band full-width at half-maximum (G-FWHM) in a Raman spectrum of 40 (cm−1) or less.