Lithium Metal Negative Electrode Artificial SEI Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium metal batteries face issues with mechanical stability and flexibility of the native Solid Electrolyte Interphase (SEI) during cycling, leading to inhomogeneous lithium plating, dendrite formation, and capacity fading due to inadequate accommodation of volumetric changes and electrolyte decomposition.
Innovation Solution
A protective interfacial layer is formed on the lithium metal substrate using a precursor solution containing an organophosphate, dissolved lithium ions, and a nonpolar organic solvent, which is then heated to create a composite structure with a carbon-based matrix and lithium-containing inorganic compounds, enhancing mechanical stability and preventing undesirable reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a native SEI layer forms in-situ on the lithium metal surface during first charge, then it provides electrical insulation and ionic conductivity to prevent side reactions, but it lacks mechanical stability and flexibility to accommodate volumetric changes during cycling
Solution Approach 1:
The patent applies composite materials by creating an artificial SEI layer with a dual-component structure: LiF provides mechanical stability and chemical inertness, while Li3PO4 provides ionic conductivity. This composite structure combines the advantages of different materials to simultaneously achieve mechanical stability and ionic conductivity, resolving the contradiction between protection reliability and compositional stability.
2Adaptability or versatility
If the native SEI structure cannot accommodate repeated volumetric changes during cycling, then the SEI becomes damaged and breaks, but this leads to inhomogeneous lithium plating and dendrite formation
Solution Approach 1:
The patent applies parameter changes by modifying the mechanical properties of the SEI layer through the introduction of LiF, which has high mechanical strength and flexibility. This changes the physical parameters of the SEI layer to enable it to accommodate volumetric expansion and contraction during cycling, preventing damage and maintaining uniform lithium deposition.
3Reliability
If in-situ formation of native SEI occurs through electrolyte decomposition, then the SEI forms protectively, but active lithium is consumed leading to capacity fading and increased battery resistance
Solution Approach 1:
The patent applies preliminary action by pre-forming the artificial SEI layer containing LiF and Li3PO4 before battery operation begins. This preliminary formation process uses a controlled precursor solution rather than uncontrolled electrolyte decomposition, achieving the protective function while minimizing active lithium consumption and avoiding capacity fading.
4Object-affected harmful factors
If the native SEI layer is formed to prevent contact between lithium metal and electrolyte, then side reactions are reduced, but the layer increases interfacial impedance and reduces lithium-ion transfer rates
Solution Approach 1:
The patent applies local quality by creating an SEI layer with spatially differentiated functions: LiF-rich regions provide mechanical stability and chemical protection, while Li3PO4-rich regions provide high ionic conductivity for rapid lithium-ion transfer. This local differentiation of material properties allows the layer to simultaneously prevent side reactions and maintain high power.
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 solution significantly reduces interfacial impedance, improves lithium-ion transfer rates, and increases cycle stability by suppressing dendrite formation and enhancing uniformity of lithium stripping and plating processes.
Implementation Method 1
a precursor solution is applied to a major surface of a lithium metal substrate to form a precursor coating thereon
Implementation Method 2
At least a portion of the nonpolar organic solvent may be removed from the precursor coating to form a protective interfacial layer
Implementation Method 3
the lithium metal in the negative electrode is oxidized to lithium ions (Li+) during discharge of the battery
Implementation Method 4
the lithium ions are reduced to lithium metal and re-deposited
Data Source
AI summary
A negative electrode for an electrochemical cell of a secondary lithium metal battery is manufactured by a method in which a precursor solution is applied to a major surface of a lithium metal substrate to form a precursor coating thereon. The precursor solution includes an organophosphate, a nonpolar organic solvent, and a lithium-containing inorganic ionic compound dissolved therein. At least a portion of the nonpolar organic solvent is removed from the precursor coating to form a protective interfacial layer on the major surface of the lithium metal substrate. The protective interfacial layer exhibits a composite structure including a carbon-based matrix component and a lithium-containing dispersed component. The lithium-containing dispersed component is embedded in the carbon-based matrix component and includes a plurality of lithium-containing inorganic ionic compounds, e.g., lithium phosphate (Li3PO4) and lithium nitrate (LiNO3).