Bi-substituted LLZO Solid Electrolyte Low-Temperature Sintering
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Solution Overview
Problem
Current solid electrolytes for all-solid-state lithium batteries face challenges in achieving low grain boundary resistance at low firing temperatures, leading to reduced lithium ion conductivity, and mutual diffusion issues when co-fired with active materials.
Innovation Solution
A solid electrolyte with the compositional formula Li7(La3-xBix)Zr2O12, where 0.05<x<0.40, is produced using a method involving mixing raw materials, followed by calcination and crystallization at controlled temperatures, which suppresses mutual diffusion with active materials and enhances lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If solid electrolyte particles are compression molded to form a molded body, then the solid electrolyte can be shaped according to desired geometry, but the contact between particles is insufficient and grain boundary resistance becomes high
Solution Approach 1:
The invention changes the chemical composition parameters of the solid electrolyte by substituting La with Bi in specific ratios (0.05 ≤ x ≤ 0.40 in Li7(La3-xBix)Zr2O12), which fundamentally alters the material properties to enable low-temperature sintering while maintaining high lithium ion conductivity and reducing grain boundary resistance
2Reliability
If solid electrolyte particles are sintered at high temperature (1000°C or higher) to reduce grain boundary resistance, then lithium ion conductivity improves, but the formulation is likely to change and it becomes difficult to produce a solid electrolyte molded body with desired physical properties
Solution Approach 1:
The invention changes the composition parameters by introducing Bi substitution to lower the sintering temperature requirement, and changes the thermal processing parameters by using low-temperature sintering (900-1000°C) instead of high-temperature sintering, thereby preventing formulation change while achieving low grain boundary resistance
Solution Approach 2:
The invention creates a composite solid electrolyte material by substituting La with Bi in the lithium lanthanum zirconate structure, forming a new compositional system Li7(La3-xBix)Zr2O12 that combines the advantages of both materials to achieve low-temperature processability and high performance
3Temperature
If elements are substituted in lithium lanthanum zirconate to enable low-temperature sintering, then sintering temperature decreases, but a solid electrolyte capable of obtaining a molded body with sufficiently low grain boundary resistance at sufficiently low firing temperature has not yet been obtained
Solution Approach 1:
The invention optimizes the substitution parameter x in the compositional formula Li7(La3-xBix)Zr2O12 where 0.05 ≤ x ≤ 0.40, finding the precise balance that simultaneously achieves low sintering temperature (900-1000°C) and low grain boundary resistance, resolving the trade-off between temperature reduction and performance maintenance
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 provides a solid electrolyte with excellent bulk lithium ion conductivity and low grain boundary resistance at a low firing temperature, effectively preventing mutual diffusion with active materials, thereby improving battery performance.
Implementation Method 1
a solid electrolyte that has an excellent bulk lithium ion conductivity
Implementation Method 2
a first heating step of subjecting the mixture to a first heating treatment thereby forming a calcined body; and a second heating step of subjecting the calcined body to a second heating treatment thereby forming a crystalline solid electrolyte
Implementation Method 3
a method of fusing solid electrolyte particles by sintering at a high temperature of 1000° C. or higher after compression molding the particles
Data Source
AI summary
A solid electrolyte according to the present disclosure is represented by the following compositional formula (1).Li7(La3-xBix)Zr2O12 (1)In the formula (1), x satisfies 0.05<x<0.40.