All-solid battery gradient electrode design
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Solution Overview
Problem
All-solid lithium batteries face challenges in achieving reduced diffusion resistance and improved rate characteristics, particularly due to increased resistance from thicker electrode active material layers and limited durability from expansion and contraction during charging and discharging.
Innovation Solution
The battery design incorporates a composition distribution in the electrode active material layers where the local volume ratio of the electrode active material increases towards the current collector, accompanied by increased voidage, facilitating electron and lithium ion conductivity while absorbing mechanical displacement, thereby enhancing durability and reducing diffusion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the electrode active material layer is increased to achieve high capacity, then the battery capacity is improved, but the resistance increases and output characteristic deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of active material and solid electrolyte within the electrode layer. The active material concentration is higher near the current collector and lower near the solid electrolyte layer interface, while the solid electrolyte concentration is higher near the interface and lower near the current collector. This spatial variation in composition optimizes both capacity and resistance characteristics by ensuring efficient ion transport pathways while maintaining sufficient active material volume.
2Reliability
If a solid electrolyte layer is introduced to improve safety and simplify structure, then safety is improved and manufacturing cost is reduced, but diffusion resistance increases and rate characteristic deteriorates
Solution Approach 1:
The patent merges the solid electrolyte layer with the electrode active material layer to form an integrated composite structure. The solid electrolyte is not merely a separate layer but is incorporated within the electrode matrix, creating continuous ion transport pathways that reduce diffusion resistance while maintaining the safety benefits of solid electrolyte technology.
Solution Approach 2:
The patent utilizes a porous structure within the electrode active material layer that contains the solid electrolyte. This porous architecture provides numerous pathways for ion diffusion, reducing the overall diffusion resistance despite the presence of the solid electrolyte, which inherently has higher resistance compared to liquid electrolytes.
3Quantity of substance
If the electrode active material layer is made thicker to increase capacity, then capacity is improved, but warpage and crack due to expansion and contraction increase
Solution Approach 1:
The patent applies local quality by varying the composition of the electrode layer throughout its thickness. The region near the current collector has higher active material content to accommodate expansion, while the region near the solid electrolyte interface has higher solid electrolyte content. This gradient structure allows differential accommodation of expansion and contraction forces, reducing warpage and crack formation.
Solution Approach 2:
The patent creates a composite material structure by combining the electrode active material with the solid electrolyte in a specific spatial arrangement. This composite structure provides mechanical reinforcement and stress distribution that mitigates warpage and crack formation during charging and discharging cycles, while maintaining high capacity through the thick electrode layer.
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
This design effectively increases the current magnitude, improves rate characteristics, and enhances the battery's durability by forming efficient electron and ion conducting paths while managing mechanical stress through voids in the electrode active material layers.
Implementation Method 1
a solid electrolyte layer that is formed between the positive electrode and the negative electrode
Implementation Method 2
a voidage of the electrode active material layer increases as the part of the electrode active material layer approaches from the interface of the solid electrolyte layer toward the interface of the current collector
Data Source
AI summary
An all-solid battery is formed so that an electrode active material layer of at least one of positive and negative electrodes has a composition distribution such that a local volume ratio, expressed by a ratio of a volume of an electrode active material contained in a part of the electrode active material layer with respect to a volume of a solid electrolyte material contained in the part of the electrode active material layer, increases as the part of the electrode active material layer approaches from an interface of the solid electrolyte layer toward an interface of a current collector in a thickness direction of the electrode active material layer, and a voidage of the electrode active material layer increases as the part of the electrode active material layer approaches from the interface of the solid electrolyte layer toward the interface of the current collector in the thickness direction.