Solid-State Battery Cathode Composition Balancing Capacity and Strength
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Solution Overview
Problem
The performance of all-solid-state batteries, particularly in terms of lifetime and capacity, is not satisfactorily improved by optimizing the properties of the positive electrode, specifically ionic and electrical conductivity, in existing technologies.
Innovation Solution
A positive electrode for an all-solid-state battery comprising a positive electrode active material, a solid electrolyte, and a binder, with the positive electrode active material content exceeding 70% by weight, and a specific composition that includes sulfide-based solid electrolytes and a conductive material, ensuring a tensile strength of 0.01 to 1.0 MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of positive electrode active material is increased to improve capacity, then the battery capacity and energy density are improved, but the mechanical strength and structural stability of the positive electrode deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of multiple components in the positive electrode. Specifically, it sets the positive electrode active material content at 60-90 wt%, solid electrolyte at 5-30 wt%, and binder at 1-20 wt%, with further subdivisions for different material types. This optimized parameter range resolves the contradiction by finding the balance point where sufficient active material provides high capacity while maintaining enough binder and solid electrolyte to ensure structural integrity and ionic conductivity.
Solution Approach 2:
The patent employs composite materials by creating a multi-component positive electrode structure combining positive electrode active material, solid electrolyte, and binder in specific proportions. This composite approach allows the electrode to simultaneously achieve high capacity (from active material), structural stability (from binder network), and ionic conductivity (from solid electrolyte), resolving the contradiction between capacity and mechanical strength through synergistic material combination.
2Reliability
If the content of solid electrolyte is increased to improve ionic conductivity, then the ionic conductivity and lifetime are improved, but the battery capacity and energy density deteriorate
Solution Approach 1:
The patent resolves this contradiction through parameter optimization by setting the solid electrolyte content within the specific range of 5-30 wt% of the total positive electrode weight. This controlled parameter range ensures sufficient ionic conductivity for long battery lifetime while preventing excessive solid electrolyte content that would reduce the proportion of capacity-providing active material, thus maintaining high energy density.
3Strength
If the content of binder is increased to improve mechanical strength, then the structural stability is improved, but the ionic conductivity and battery performance deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the binder content within 1-20 wt% of the total positive electrode weight. This optimized parameter range provides sufficient binder to ensure mechanical strength and structural stability of the positive electrode while preventing excessive binder content that would block ionic pathways and reduce ionic conductivity, thus resolving the contradiction between structural stability and ionic conductivity.
Data Source
Figure 1
Figure 2(a)~2(c)
AI summary
The present invention relates to a positive electrode for an all-solid-state battery that can improve the performance of the battery by physically optimizing the properties of the positive electrode that directly affect the lifetime and capacity expression of the battery, and an all-solid-state battery comprising same. The positive electrode for an all-solid-state battery comprises a positive electrode active material, a solid electrolyte and a binder, wherein the content of the positive electrode active material exceeds 70% by weight.