Lithium Chloride Derivative Solid Electrolyte for Safe Li Metal Batteries
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Solution Overview
Problem
Conventional Li-ion batteries pose safety risks due to flammable organic solvents and stability issues with lithium metal anodes, necessitating the development of solid lithium ion conductors with high conductivity, stability, and ease of synthesis for all-solid-state batteries.
Innovation Solution
Development of lithium chloride derivative compounds with specific crystal structures, such as Li2ZnCl4 and LiAlCl4, which exhibit high lithium ion conductivity and stability, suitable for use as solid electrolytes and electrode components in lithium ion and lithium metal batteries, maintaining a monoclinic phase of the P21/c space group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flammable organic liquid electrolyte is used in Li-ion batteries, then high lithium ion 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 chloride derivative compounds with P21/c crystal structure. This phase transition eliminates flammability while maintaining lithium ion conductivity, directly resolving the safety contradiction.
Solution Approach 2:
The invention uses composite lithium chloride derivative compounds containing multiple elements (Li, M, M1, Cl, X) in specific ratios. These composite materials combine the benefits of high ionic conductivity with enhanced safety and stability, replacing flammable organic electrolytes.
2Object-generated harmful factors
If solid Li-ion conductor is used to replace liquid electrolyte, then safety is improved, but lithium ion conductivity decreases
Solution Approach 1:
The patent optimizes key parameters including Li content (x), M1 content (y), and M content (z) in the compound formula Lix-y(M1)yM1-z(M2)zCl4-o(X)o. By adjusting these compositional parameters and controlling crystal structure (P21/c space group), the material achieves high ionic conductivity (≥10^-6 S/cm) while maintaining solid state safety.
Solution Approach 2:
The invention creates specific local structural environments within the crystal lattice that facilitate lithium ion transport. The P21/c crystal structure provides favorable local coordination environments and diffusion pathways, enabling high ionic conductivity in the solid state.
3Quantity of substance
If lithium metal anode is used, then battery capacity is improved, but stability deteriorates due to dendrite formation
Solution Approach 1:
The solid lithium chloride derivative electrolyte acts as an intermediary layer between the lithium metal anode and cathode. This intermediary solid electrolyte prevents direct contact and electron transfer that would otherwise cause dendrite formation, while still allowing lithium ion transport for high capacity.
Solution Approach 2:
The invention extracts and eliminates the harmful electron conduction pathway that leads to dendrite formation, while preserving the beneficial lithium ion conduction. The solid electrolyte selectively blocks electrons but allows lithium ions to pass, preventing dendrite instability.
4Object-generated harmful factors
If conventional solid Li-ion conductors are used, then safety is improved, but synthesis complexity increases
Solution Approach 1:
The patent employs relatively simple and cost-effective synthesis methods using common starting materials and standard solid-state reaction techniques. The synthesis process is designed to be straightforward and scalable, making the solid electrolyte material easier to manufacture compared to conventional complex solid conductors.
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 compounds demonstrate lithium ion conductivity ranging from 0.1 to 3 mS/cm at 300K and activation energy between 0.15 to 0.40 eV, enhancing the safety and performance of solid-state lithium batteries while being cost-effective and easy to synthesize.
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
Because of this strong reducing capability when the lithium metal of an anode contacts a solid-state Li+ conductor containing cation components different from lithium ion, the lithium reduces the cation specie to a lower oxidation state
Data Source
AI summary
Solid-state lithium ion electrolytes of metal lithium chloride derivative compounds having a crystal morphology in the P21/c space group are provided as materials for conducting lithium ions. An activation energy of the lithium aluminum chloride derivative compounds is from 0.15 to 0.40 eV and conductivities are from 0.01 to 3 mS/cm at 300K. Compounds of specific formulae are provided and methods to alter the materials with inclusion of aliovalent ions shown. Lithium batteries containing the composite lithium ion electrolytes and electrodes containing the lithium aluminum chloride derivative compounds are also provided.