Lithium Metal Sulfide Solid Electrolytes for Safe Battery Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Li-ion batteries face safety risks due to flammable organic solvents and stability issues with existing solid-state lithium ion conductors, which limit their use in large-scale energy storage and are prone to dendrite formation and chemical degradation when in contact with lithium metal.
Innovation Solution
Development of novel lithium metal sulfide compounds, specifically materials of the form Liy(M1)x1AlS2, LiyAl1-x2(M2)x2S2, and LiyAlS2-x3(X)x3, which exhibit high Li+ conductivity and stability, with activation energies between 0.2 to 0.45 eV, suitable for use as solid-state electrolytes in lithium ion batteries and as protective coating layers for electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flammable organic liquid electrolyte is used in Li-ion batteries, then ionic conductivity is achieved, but safety risk increases due to flammability
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid phase by using lithium metal sulfide compounds. This phase transition eliminates flammability while maintaining ionic conductivity, as the solid-state material does not exhibit the combustion properties of organic liquids.
Solution Approach 2:
The patent employs composite lithium metal sulfide materials with specific crystal structures (such as Li10GeP2S12 and Li6.75Si0.25P0.75S4) that combine high ionic conductivity with chemical stability. These composite materials replace flammable organic electrolytes while providing comparable or superior performance.
2Reliability
If conventional solid Li-ion conductors are used, then safety is improved, but electrochemical stability deteriorates when in contact with lithium metal
Solution Approach 1:
The patent modifies the chemical composition and crystal structure parameters of solid electrolytes by incorporating specific cations (Ge4+, Si4+, P5+) and adjusting stoichiometry. These parameter changes create materials with matched electrochemical stability that resist reduction by lithium metal while maintaining high Li+ conductivity.
Solution Approach 2:
The patent develops composite lithium metal sulfide materials combining multiple elements (Li-M-S systems) where the synergistic interaction between different cations enhances both electrochemical stability and ionic conductivity. Examples include Li10GeP2S12 and Li6.75Si0.25P0.75S4 which exhibit superior stability compared to single-element sulfides.
3Quantity of substance
If lithium metal anode is used, then capacity is improved, but dendrite formation increases leading to safety risks
Solution Approach 1:
The patent introduces solid lithium metal sulfide electrolytes as an intermediary layer between the lithium metal anode and cathode. This intermediary solid electrolyte suppresses dendrite formation by providing a uniform Li+ transport pathway with high conductivity, preventing the direct contact and short-circuiting that would otherwise occur with dendritic growth.
4Reliability
If solid-state electrolyte is used, then safety and thermal stability are improved, but manufacturing cost increases
Solution Approach 1:
The patent optimizes synthesis parameters including sintering temperature, atmosphere control, and precursor composition to reduce manufacturing complexity. By controlling these parameters, the patent enables cost-effective production of high-purity lithium metal sulfide electrolytes with desired crystal structures and properties.
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 materials provide enhanced mechanical and thermal stability, reduce grain boundary resistance, and are cost-effective, enabling improved performance and safety in lithium ion batteries by maintaining high conductivity and stability against chemical, electrochemical, and thermal degradation.
Implementation Method 1
A primary function of the solid Li-ion 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
Data Source
AI summary
Solid-state lithium ion electrolytes of lithium metal sulfide based composites are provided which contain an anionic framework capable of conducting lithium ions. An activation energy of the lithium metal sulfide composites is from 0.2 to 0.45 eV and conductivities are from 10−4 to 3.0 mS/cm at 300K. Composites of specific formulae are provided and methods to alter the composite materials with inclusion of aliovalent ions shown. Lithium batteries containing the composite lithium ion electrolytes are also provided. Electrodes containing the lithium metal sulfide based composites and batteries with such electrodes are also provided.