Solid-State Battery Electrolyte Composite for Interface Adhesion
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Solution Overview
Problem
All-solid-state lithium-ion batteries using oxide-based solid electrolytes face issues with adhesion between the solid electrolyte and active materials, leading to increased grain-boundary resistance and decreased lithium-ion conductivity, resulting in reduced discharging capacity, especially upon repeated charging and discharging.
Innovation Solution
A composite is developed comprising a lithium composite metal oxide-based first electrolyte portion and a second electrolyte portion with specific compositions, where the second electrolyte portion covers the active material and interposes between the first electrolyte and the active material, enhancing adhesion and preventing grain-boundary resistance, thereby maintaining discharging capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide-based solid electrolyte is used to achieve high lithium-ion conductivity and safety, then insulation properties and chemical stability are improved, but adhesion between solid electrolyte and active material deteriorates
Solution Approach 1:
A surface treatment layer comprising lithium composite metal oxide is introduced as an intermediary between the oxide-based solid electrolyte and the active material. This intermediate layer improves interfacial adhesion and reduces grain-boundary resistance while maintaining the high safety and chemical stability of the oxide-based solid electrolyte.
Solution Approach 2:
The invention uses composite materials by combining oxide-based solid electrolyte with a surface treatment layer of lithium composite metal oxide. This composite structure leverages the high safety and chemical stability of the oxide-based electrolyte while adding the adhesion-enhancing properties of the lithium composite metal oxide surface layer.
2Reliability
If oxide-based solid electrolyte is used to achieve high lithium-ion conductivity, then insulation properties are improved, but grain-boundary resistance increases
Solution Approach 1:
The surface treatment layer of lithium composite metal oxide acts as an intermediary that reduces grain-boundary resistance at the interface between the oxide-based solid electrolyte and active material, while preserving the excellent insulation properties of the bulk oxide-based electrolyte.
Solution Approach 2:
The invention applies local quality modification by treating only the surface region of the solid electrolyte with lithium composite metal oxide. The bulk oxide-based electrolyte maintains its high insulation properties, while the surface layer provides reduced grain-boundary resistance and improved adhesion.
3Reliability
If solid electrolyte is used to prevent electrolyte leakage and volatilization, then safety is improved, but discharging capacity retention deteriorates upon repeated charging and discharging
Solution Approach 1:
The lithium composite metal oxide surface treatment layer serves as a protective intermediary that maintains stable electrical contact between the solid electrolyte and active material during repeated charging and discharging cycles, preventing capacity fading while preserving the safety advantages of solid electrolyte.
Solution Approach 2:
The surface treatment layer is applied in advance to cushion against the degradation that occurs during repeated charging and discharging. This pre-applied protective layer prevents direct contact and potential degradation between the solid electrolyte and active material, maintaining discharging capacity retention over time.
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 composite ensures excellent adhesion and conductivity, maintaining discharging capacity and preventing capacity degradation even after repeated charging and discharging cycles.
Implementation Method 1
adhesion between the solid electrolyte and an active material or adhesion between solid electrolyte particles may not be sufficiently excellent
Implementation Method 2
an oxide-based solid electrolyte is widely known, which has high lithium-ion conductivity
Data Source
AI summary
A composite according to the present disclosure includes an active material, a crystalline first electrolyte portion containing a lithium composite metal oxide represented by Formula (1), and a second electrolyte portion containing a lithium composite metal oxide represented by Formula (2) and configured to cover at least a part of a surface of the active material. At least a part of the first electrolyte portion is bonded to the active material through the second electrolyte portion,(Li7−3x+yGax) (La3−yCay) Zr2O12 (1)in which 0.10≤x≤1.00, and 0.00<y≤0.30, andLi7−zLa3(Zr2−zMz)O12 (2)in which the element M is two or more elements selected from the group consisting of Nb, Ta, and Sb, and 0.00<z<2.00.