Oxide Ion Conductor Composition for Safe Lithium Metal Batteries
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Solution Overview
Problem
Lithium metal batteries face safety risks due to the high reactivity between lithium metal and liquid electrolytes, leading to potential fires or explosions, necessitating the development of improved battery materials with enhanced safety and ionic conductivity.
Innovation Solution
The development of an ion conductor with specific oxide compositions, represented by Formulae 1 to 3, which includes Group 4 elements and certain dopants, providing improved ionic conductivity and electrochemical stability, is integrated into a positive electrode, solid electrolyte, and lithium battery design, along with a method of preparation involving heat-treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as a negative electrode with liquid electrolyte, then high capacity is achieved, but safety deteriorates due to high reactivity causing fire or explosion risks
Solution Approach 1:
A solid electrolyte layer comprising Li4±xM1−x′M′x′O4 oxide is introduced as an intermediary between the lithium metal negative electrode and the liquid electrolyte. This solid electrolyte acts as a protective barrier that prevents direct contact and high reactivity between lithium metal and liquid electrolyte, thereby eliminating fire or explosion risks while maintaining lithium capacity through effective ion conduction.
2Reliability
If solid electrolyte is used to improve safety, then reactivity between lithium metal and electrolyte is reduced, but ionic conductivity at high temperature must be improved
Solution Approach 1:
The chemical composition parameters of the solid electrolyte are optimized by controlling the ratios of Li, M, and M′ elements according to the formula Li4±xM1−x′M′x′O4 where 0≤x≤1 and 0≤x′≤1. This parameter optimization enhances ionic conductivity at high temperatures (about 60°C) while maintaining the safety benefits of the solid electrolyte structure.
Solution Approach 2:
The solid electrolyte is designed as a composite oxide material combining Li4±xM1−x′M′x′O4 with specific element combinations (M from Group 4, M′ from Groups 2, 3, 5, 12, or 13). This composite material structure achieves both high safety and improved ionic conductivity through synergistic effects of different elements.
3Loss of energy
If dopants are added to improve ionic conductivity, then electrochemical stability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The dopant elements (M and M′) are pre-mixed with lithium compounds in predetermined ratios according to the target formula Li4±xM1−x′M′x′O4 before sintering. This preliminary mixing ensures uniform distribution of dopants throughout the solid electrolyte material, simplifying the manufacturing process while achieving the desired ionic conductivity and electrochemical stability.
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 ion conductor achieves high ionic conductivity at elevated temperatures, reducing internal resistance and enhancing safety by providing a pathway for lithium ions, thereby improving the performance and safety of lithium batteries.
Implementation Method 1
The ion conductor achieves high ionic conductivity at elevated temperatures, reducing internal resistance and enhancing safety by providing a pathway for lithium ions
Implementation Method 2
heat-treating the precursor mixture in an oxidizing atmosphere to prepare a first heat-treatment product; heat-treating the pellet in an oxidizing atmosphere, a reducing atmosphere, or a combination thereof
Data Source
AI summary
A lithium battery includes: a positive electrode having a positive active material; a negative electrode including lithium metal; and a solid electrolyte disposed therebetween. The solid electrolyte contains at least one oxide represented by Li4±xM1−x′M′x′O4 (Formula 1), Li4−yM″O4-yA′y (Formula 2), or Li4+4zM′″1−zO4 (Formula 3), wherein and 0≤x23 1 and 0≤x′≤1, M is a Group 4 element, and M′ is an element of Group 2, 3, 5, 12, or 13, a vacancy, or a combination thereof, with the proviso that when M is Zr, then x≠0, x′≠0 and M′ is Be, Ca, Sr, Ba, Ra, Cd, Hg, Cn, Ga, In, TI, an element of Group 3 or 5, or a combination thereof; 0≤y≤1, M″ is a Group 4 element, and A′ includes at least one halogen, with the proviso that when M″ is Zr, then y≠0; and 0<z<1, and M′″ is a Group 4 element.