Si Electrode Layer Overlap Control for Low Initial Resistance
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Solution Overview
Problem
The initial resistance of electrode layers containing silicon (Si) as an active material increases unexpectedly when the dispersing state of the electrode active material and solid electrolyte is too high or too low, despite the theoretical capacity of Si being advantageous for high energy density.
Innovation Solution
The electrode layer is designed with a specific overlapping degree (D) of Si and A elements, within a specified range calculated from SEM-EDX measurements, and includes a solid electrolyte with controlled oxygen content and Hansen solubility parameters, along with a porous structure and appropriate ratios of electrode active material and solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dispersing state of the electrode active material and solid electrolyte is increased to decrease initial resistance, then the initial resistance decreases, but when the dispersing state is too high, the initial resistance increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the overlapping degree D within a specific numerical range (greater than -0.472 and 0 or less). This quantitative parameter control resolves the contradiction by identifying the optimal dispersing state that minimizes initial resistance while preventing the resistance increase that occurs at excessive dispersing states. The overlapping degree serves as a critical parameter that balances electrode active material and solid electrolyte distribution.
Solution Approach 2:
The patent employs feedback through SEM-EDX measurement to calculate the overlapping degree D, which provides quantitative information about the dispersing state. This measurement feedback enables precise adjustment and control of the electrode layer composition to maintain the optimal overlapping degree range, thereby consistently achieving low initial resistance while avoiding the adverse effects of excessive dispersing.
2Quantity of substance
If the overlapping degree of Si and A elements is increased to improve energy density, then the energy density increases, but the initial resistance may increase if the overlapping degree is too high
Solution Approach 1:
The patent resolves this contradiction by establishing a specific numerical range for the overlapping degree D (greater than -0.472 and 0 or less). This parameter control simultaneously optimizes both energy density and initial resistance by preventing excessive overlap that would increase resistance while maintaining sufficient overlap for high energy density. The overlapping degree becomes a balanced parameter that satisfies both requirements.
Data Source
AI summary
A main object of the present disclosure is to provide an electrode layer of which initial resistance is low. The present disclosure achieves the object by providing an electrode layer including an electrode active material including a Si element, and a solid electrolyte including an A element as a main component of anion, wherein when an overlapping degree D of the Si element and the A element is calculated based on an element mapping image obtained by a SEM-EDX measurement, the D is larger than −0.472 and 0 or less.