Lithium Metal Sulfide Solid Electrolytes for Safe Battery Design
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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-state electrolytes when in contact with lithium metal, limiting their use in large-scale energy storage and requiring materials with high Li+ conductivity, low activation energy, and electrochemical stability.
Innovation Solution
Development of novel lithium metal sulfide compounds, such as Liy(M1)x1InSiS6 and Liy(M4)z1MnGe2S7, which exhibit high Li+ conductivity (10−2 to 10 mS/cm) and low activation energy (0.27 to 0.37 eV), serving as solid-state electrolytes or electrode coating layers, and are synthesized using ab initio molecular dynamics simulations and aliovalent substitution to enhance stability and reduce grain boundary resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Li-ion batteries use flammable organic solvent electrolytes, then high Li+ conductivity is achieved, but safety risk increases due to flammability
Solution Approach 1:
The patent transitions the electrolyte from liquid phase (flammable organic solvents) to solid phase (lithium metal sulfide compounds), eliminating flammability while maintaining ionic conductivity. The solid-state electrolyte materials such as Li2In2SiS6 and Li4MnGe2S7 provide a non-flammable alternative that conducts Li+ ions effectively.
2Reliability
If existing solid-state electrolytes 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 parameters of solid-state electrolytes by incorporating specific elements (In, Si, Mn, Ge, S) in controlled ratios to achieve both electrochemical stability and high ionic conductivity. The materials Li2In2SiS6 and Li4MnGe2S7 are designed with specific stoichiometries that prevent degradation when in contact with lithium metal anodes.
Solution Approach 2:
The patent employs composite lithium metal sulfide compounds combining multiple elements (Li, In, Si, Mn, Ge, S) to achieve synergistic properties. These composite materials provide both electrochemical stability and high Li+ conductivity, overcoming the limitations of single-element solid electrolytes.
3Stability of the object's composition
If solid-state electrolytes are used, then mechanical and thermal stability are improved, but Li+ conductivity decreases compared to liquid electrolytes
Solution Approach 1:
The patent optimizes the crystal structure and composition parameters of lithium metal sulfide compounds to enhance Li+ ionic conductivity. By adjusting the ratios of constituent elements and controlling synthesis conditions, the materials achieve conductivity levels comparable to liquid electrolytes while maintaining solid-state mechanical and thermal 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
These materials provide improved mechanical and thermal stability, enhanced Li+ conductivity, and resistance to electrochemical degradation, facilitating the development of safer and more efficient solid-state lithium batteries with potential for high power and energy density.
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
Implementation Method 2
the solid Li-ion conductive phase... blocking the direct transport of electrons between electrodes within the battery
Implementation Method 3
the lithium reduces the cation specie to a lower oxidation state... Li3PS4+5Li→P+4Li2S
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. 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 materials and batteries with such electrodes are also provided.