Mixed Anion Solid Electrolyte for Stable Lithium Metal Batteries
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Solution Overview
Problem
Conventional Li-ion batteries face safety risks due to flammable organic solvents and stability issues with existing solid Li-ion conductors when in contact with lithium metal anodes, limiting their use in large-scale energy storage and requiring new materials with high Li+ conductivity and stability.
Innovation Solution
Development of composite solid-state lithium ion electrolytes with a composite material having at least 94 mole % lithium ions and multiple anions, specifically formulated as Li7-nxMxBr3O2, Li10-nyMyN3Br, Li5-nzMzNCl2, Li4-nwMwNCl, Li6-ntMtNBr3, and Li6-nsMsNI3, which exhibit high Li+ conductivity and low activation energy, ensuring stability with lithium metal anodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid Li-ion conductors (such as Li3PS4, Li10GeP2S12, Li7La3Zr2O12) are used, then Li+ conductivity can reach 1-10 mS/cm level, but they undergo chemical degradation when in contact with lithium metal anode due to reduction of cation species
Solution Approach 1:
The patent changes the chemical composition parameters of the solid electrolyte by using only lithium ions as cations and combining multiple anion types (O2-, S2-, N3-, F-, Cl-, Br-, I-). This compositional parameter change eliminates secondary cations that would be reduced by lithium metal, thereby preventing chemical degradation while maintaining high Li+ conductivity through the anionic framework structure.
Solution Approach 2:
The patent employs composite materials containing multiple types of anions (such as O and Br, or S and N, or N and I) within a single solid electrolyte phase. This composite anionic structure creates a stable chemical environment resistant to lithium metal reduction while the disordered anionic framework facilitates lithium ion conduction pathways, achieving both stability and conductivity.
2Power
If lithium metal anode is used to achieve high energy density, then battery performance is improved, but it reduces most known cationic species to lower oxidation state causing deterioration of solid-state conductor
Solution Approach 1:
The patent changes the cation composition parameter to contain exclusively lithium ions (Li+) with a fixed +1 oxidation state. By eliminating secondary cations (such as P5+, Ge4+, La3+, Zr4+) that would be reduced by lithium metal, the system maintains oxidation state stability even when in contact with lithium metal anode, enabling high energy density applications.
Solution Approach 2:
The patent creates a chemically inert environment at the anode interface by designing a solid electrolyte composition that is resistant to reduction by lithium metal. The anionic framework (combining multiple anion types) provides a stable chemical environment that prevents redox reactions, effectively creating an inert interface that allows lithium metal to function at high energy density without causing deterioration.
3Ease of manufacture
If flammable organic solvent electrolyte is used, then Li-ion batteries can be manufactured with conventional technology, but safety risk increases due to flammability
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid (organic solvent) to solid state. By formulating a solid electrolyte with high Li+ conductivity (at least 10^-6 S/cm at room temperature) and low activation energy (0.5 eV or less), the system maintains manufacturability through conventional solid-state processing while eliminating the flammability hazard inherent in organic liquid electrolytes.
Solution Approach 2:
The patent replaces flammable organic solvents with an inorganic solid electrolyte composed of lithium ions and multiple anions in an anionic framework. This creates a chemically inert and non-flammable environment within the battery, eliminating fire risks while maintaining ionic conductivity through the solid-state anionic structure.
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
These electrolytes achieve Li+ conductivity of at least 10−6 S/cm at room temperature and low activation energy, maintaining stability with lithium metal anodes, enhancing safety and performance for solid-state lithium batteries.
Implementation Method 1
A primary function of the solid Li-conductive phase, usually called solid Li-ion conductor or solid state electrolyte, is to conduct Li ions from the anode side to the cathode side during discharge and from the cathode side to the anode side during charge
Implementation Method 2
conduct Li ions from the anode side to the cathode side during discharge and from the cathode side to the anode side during charge while blocking the direct transport of electrons between electrodes within the battery
Implementation Method 3
an activation energy for lithium ion migration in the solid state lithium ion electrolyte is 0.5 eV or less
Data Source
AI summary
A solid-state lithium ion electrolyte is provided which contains a composite material having at least 94 mole % lithium ions as cation component and multiple anions in an anionic framework capable of conducting lithium ions. An activation energy for lithium ion migration in the solid state lithium ion electrolyte is 0.5 eV or less. Composites of specific formulae are provided. A lithium battery containing the composite lithium ion electrolyte is also provided.