Buffered Pre-Lithiated Anode Coatings for Dendrite Suppression
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Solution Overview
Problem
Lithium ion batteries face safety risks due to thermal runaway, cell breakdown, and the potential for fire or explosion, particularly when overheated or overcharged, and have limitations in fast charging rates due to lithium ion accumulation at the anode-electrolyte interface leading to metallization and dendrite growth.
Innovation Solution
The development of an anode with a buffering zone that partially masks the positive charge of lithium ions, allowing them to move into the anode material for lithiation, using electron donating groups interspaced with non-electron donating groups at a specific ratio to prevent lithium ion accumulation and dendrite growth, along with various anode active materials and coatings to enhance safety and charging rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium ion batteries use conventional anode materials, then they can store energy, but lithium ion accumulation at the anode-electrolyte interface leads to metallization and dendrite growth causing safety risks
Solution Approach 1:
The patent introduces a buffering zone comprising electron-donating groups (such as nitrogen-containing groups) as an intermediary layer between the anode active material particles and the electrolyte. This buffering zone mediates the interaction by partially masking the positive charge of lithium ions, preventing direct accumulation at the interface while still allowing lithium ions to move into the anode material for lithiation. This resolves the contradiction by eliminating the harmful accumulation effect while preserving the energy storage function.
2Productivity
If lithium ion batteries are charged at high rates, then charging speed increases, but lithium ion accumulation at the interface accelerates leading to metallization and reduced safety
Solution Approach 1:
The buffering zone acts as a mediator that enables high charging rates without the harmful effects of lithium ion accumulation. The electron-donating groups in the buffering zone partially mask the positive charge of incoming lithium ions, reducing their tendency to accumulate and metallize at the interface even during fast charging. This allows the system to achieve high productivity while maintaining reliability.
Solution Approach 2:
The patent modifies the chemical parameters at the anode-electrolyte interface by introducing electron-donating groups with specific ratios (at least 1:2 ratio of electron-donating to non-electron-donating groups). This parameter change alters the charge distribution and electrochemical environment at the interface, enabling the system to handle high charging currents without lithium metallization.
3Speed
If the anode material surface is made more reactive to accept lithium ions, then charging rate increases, but the positive charge of lithium ions accumulates leading to metallization
Solution Approach 1:
The patent applies local quality modification by creating a buffering zone with specific chemical properties (electron-donating groups) only at the surface region where lithium ions first contact the anode. This localized modification allows the surface to accept lithium ions rapidly while simultaneously neutralizing the positive charge accumulation through the electron-donating groups. The bulk anode material retains its original properties for efficient lithiation.
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
This solution significantly reduces the probability of lithium metallization and dendrite growth, enhancing the safety and enabling fast charging rates in lithium ion batteries by regulating lithium ion accumulation and ensuring stable operation during high charging rates.
Implementation Method 1
the buffering zone comprises a plurality of electron donating groups interspaced between non-electron donating groups at a ratio of at least 1:2
Data Source
AI summary
Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.