Anode Buffering Zone for Fast Charging Lithium Ion Cells
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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 are prone to lithium metallization and dendrite growth, which can lead to battery failure.
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, thereby enhancing safety and enabling fast charging rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anode materials are used, then lithium ion batteries can be manufactured with standard safety levels, but the batteries are prone to thermal runaway, cell breakdown, and fire or explosion when overheated or overcharged
Solution Approach 1:
A buffering zone comprising electron-donating groups (such as nitrogen-containing groups in polymers like polyacrylonitrile, polyacrylamide, polyvinylidene fluoride, or polyvinylene carbonate) is introduced as an intermediary layer between the electrolyte and the anode active material particles. This buffering zone mediates the interaction by partially masking the positive charge of lithium ions, preventing direct contact between lithium ions and the anode material surface, thereby eliminating thermal runaway and fire hazards while enabling safe fast charging at rates of 10C, 15C, 20C, or higher.
Solution Approach 2:
The invention converts the harmful effect of lithium ion accumulation and metallization into a beneficial process by using the buffering zone to control the charging mechanism. The electron-donating groups in the buffering zone partially mask lithium ion positive charges, transforming the dangerous metallization process into a controlled lithiation process where lithium ions are gradually introduced into the anode material, preventing dendrite growth while enabling fast charging.
2Productivity
If fast charging rates are implemented, then charging speed is improved, but lithium ion accumulation at the anode interface increases, leading to metallization and dendrite growth
Solution Approach 1:
The buffering zone acts as an intermediary that controls the interface between electrolyte and anode material, enabling fast charging rates of 10C, 15C, 20C, or higher without lithium ion accumulation. The electron-donating groups in the buffering zone partially mask lithium ion positive charges, preventing direct accumulation at the anode surface and eliminating the conditions for metallization and dendrite growth while maintaining high charging productivity.
Solution Approach 2:
The invention changes the chemical and electrical parameters at the anode interface by introducing a buffering zone with electron-donating groups. This buffering zone modifies the charge distribution and lithium ion interaction parameters, allowing fast charging rates to be achieved without the harmful effects of lithium ion accumulation, metallization, and dendrite formation that occur with conventional anode materials.
3Speed
If the anode material surface is made highly reactive to accept lithium ions quickly, then charging speed improves, but the probability of metallization and dendrite growth increases
Solution Approach 1:
The buffering zone comprising electron-donating groups serves as an intermediary layer between the electrolyte and anode active material particles, enabling rapid lithium ion acceptance while preventing metallization. The electron-donating groups partially mask lithium ion positive charges, controlling the lithiation process to occur gradually within the anode material rather than through surface metallization, thus achieving high charging speed without increased metallization probability.
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 the probability of lithium metallization and dendrite growth, enhancing the safety and performance of lithium ion batteries by allowing for high charging and discharging rates while maintaining mechanical stability and preventing thermal runaway.
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.