Nitrogen-Coated Lithium Metal Particles for Stable Pre-Lithiation
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Solution Overview
Problem
Current methods for stabilizing lithium metal are inadequate for long-term storage and processing, especially in the presence of reactive solvents like N-methyl-2-pyrrolidone, as they often result in poor ionic conductivity and instability, leading to limited application in battery electrode materials.
Innovation Solution
Development of particulate lithium metal with a core/shell structure stabilized using nitrogen-containing coatings, formed by reacting metallic lithium with nitrogen-containing passivating agents at temperatures above its melting point, creating a conductive and stable nitrogen-rich outer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is treated with CO2 to form a protective layer, then corrosion resistance is improved, but the protection is insufficient for long-term storage in reactive solvents like NMP
Solution Approach 1:
The patent changes the chemical composition parameters of the protective layer by using nitrogen-containing compounds (such as trialkylamines, amides, or isocyanates) instead of CO2, and controls the thickness and composition of the shell to achieve both immediate corrosion resistance and long-term stability in reactive solvents
Solution Approach 2:
The patent creates a composite core/shell structure where the core is lithium metal and the shell is a nitrogen-containing protective layer formed by reaction with compounds like trialkylamines, amides, or isocyanates, combining the reactivity of lithium with the stability of nitrogen-containing compounds to achieve both corrosion resistance and long-term storage stability
2Reliability
If lithium metal is coated with fluorinating agents to stabilize it, then corrosion resistance is improved, but the agents are toxic and corrosive making industrial use difficult
Solution Approach 1:
The patent uses nitrogen-containing compounds (trialkylamines, amides, isocyanates) as intermediary substances that form a protective nitrogen-containing layer on lithium metal, replacing toxic fluorinating agents while achieving similar or better protective effects with improved safety and handling properties
Solution Approach 2:
The patent employs readily available, non-toxic nitrogen-containing compounds that can be easily handled and disposed of, replacing expensive and hazardous fluorinating agents, making the process suitable for industrial-scale production
3Reliability
If lithium metal is coated with polymer layers to protect it, then stability is improved, but the surface coating interferes with subsequent use for pre-lithiation of electrode materials
Solution Approach 1:
The patent creates a thin, controlled nitrogen-containing shell with specific local properties that provides protection where needed while maintaining lithium reactivity at the interface, enabling both stability during storage and functionality for pre-lithiation applications
Solution Approach 2:
The patent changes the chemical composition of the protective layer from inert polymers to nitrogen-containing compounds that can provide both protection and controlled reactivity, adjusting parameters such as shell thickness and nitrogen content to balance stability and usability
4Reliability
If lithium metal is reacted with phosphoric acid to form lithium phosphate coating, then protective layer is formed, but violent reaction occurs releasing heat and hydrogen gas
Solution Approach 1:
The patent converts the highly reactive nature of lithium, which causes violent reactions with phosphoric acid, into a benefit by using controlled reaction with nitrogen-containing compounds that form a stable protective layer without hazardous byproducts, turning potential danger into safe and effective protection
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 nitrogen-containing coating enhances the ionic conductivity and stability of lithium metal, allowing it to remain stable in reactive solvents up to 50°C for extended periods and in common electrolyte systems up to 100°C, preventing exothermic reactions and enabling safe handling and effective pre-lithiation of electrode materials.
Implementation Method 1
reacting metallic lithium with nitrogen-containing passivating agents at temperatures above its melting point
Implementation Method 2
reacting metallic lithium with nitrogen-containing passivating agents
Implementation Method 3
nitrogen-containing passivating agents
Data Source
AI summary
The invention relates to particulate lithium metal formations with substantially spherical geometry and a core consisting of metallic lithium, coated with an outer passivating yet ionically conductive layer containing nitrogen, as well as to methods for the production of same by reacting lithium metal with one or more passivation agent(s) containing nitrogen selected from the groups N2 NxHy with x = 1 or 2, and y = 3 or 4, or a compound containing only the elements C, H and N as well as, if necessary, Li, at temperatures in the range of between 60 and 300°C, preferably 100-280°C and particularly preferred to be above the lithium melting temperature of 180.5°C, in an organic, inert solvent under dispersion conditions or in an atmosphere that contains a gaseous coating agent containing nitrogen.