Oxide Solid Electrolyte Phase Control to Reduce Voids and Cracking
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Solution Overview
Problem
Oxide solid electrolytes in all-solid-state batteries have high grain boundary resistance and are prone to voids, leading to cracking and short-circuits due to dendrite formation, which compromises battery reliability.
Innovation Solution
A solid electrolyte material composed of lithium, tantalum, and phosphorus with a specific phase configuration and processing method to minimize voids, including a lithium ion conducting phase and a compound phase with controlled area proportions, and optional elements like Bi, Nb, or Ge, to enhance ion conductivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide solid electrolyte is used to achieve high ion conductivity, then grain boundary resistance is reduced, but voids form leading to cracking and short-circuits
Solution Approach 1:
The patent applies parameter changes by controlling the sintering temperature (900-1100°C) and time (1-12 hours) to optimize the density and microstructure of the solid electrolyte. By adjusting these parameters, the patent achieves high relative density (95% or more) while minimizing void formation, thereby preventing cracking and short-circuits during battery operation.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components (Li2SiO3, Ta2O5, Li3PO4, and optional additives like Li2SiO3, Li2Si2O5, Li2SiO2) to create a multi-phase solid electrolyte system. This composite approach enhances both ion conductivity and structural integrity, reducing void formation while maintaining high reliability.
2Reliability
If sintering is performed to increase relative density, then ion conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes sintering parameters (temperature range of 900-1100°C and time of 1-12 hours) to achieve the desired ion conductivity and relative density (95% or more) while keeping the process manageable. This balanced approach ensures high performance without excessive manufacturing complexity.
Solution Approach 2:
The patent performs preliminary mixing and homogenization of the oxide powders before sintering to ensure uniform composition and reduce defects. This preliminary action facilitates smoother sintering and reduces the need for complex post-processing, thereby improving ion conductivity while controlling manufacturing complexity.
3Ease of manufacture
If conventional solid electrolyte manufacturing is used, then production is simplified, but voids increase causing cracking and dendrite formation
Solution Approach 1:
The patent modifies conventional manufacturing by implementing specific sintering parameters (900-1100°C for 1-12 hours) and compositional ratios to achieve high relative density (95% or more). These changes maintain ease of manufacture through straightforward sintering while dramatically reducing void formation, thereby preventing cracking and dendrite formation.
Solution Approach 2:
The patent employs a composite oxide system (Li2SiO3-Ta2O5-Li3PO4 with optional additives) that enhances crack resistance and reduces void formation during sintering. This composite approach maintains manufacturing simplicity while significantly improving reliability by preventing structural defects.
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 solution results in a solid electrolyte with reduced voids, improving battery reliability by preventing cracking and short-circuits, and maintaining high ion conductivity, thus enhancing the performance and safety of all-solid-state batteries.
Implementation Method 1
a lithium ion conducting phase having at least lithium, tantalum, phosphorus, and oxygen as constituent elements
Data Source
AI summary
One embodiment of the present invention relates to a solid electrolyte, an all-solid-state battery, or a solid electrolyte material, and the solid electrolyte contains: a lithium ion conducting phase having at least tantalum, phosphorus, and oxygen as constituent elements; and a compound phase having at least phosphorus and oxygen as constituent elements and being free of tantalum, in which, in a scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX) image, the area proportion of the compound phase is 0.40% or more based on 100% in total of the area of the lithium ion conducting phase, the area of the compound phase, and the area of voids, and the solid electrolyte has at least lithium, tantalum, phosphorus, and oxygen as constituent elements.