Polymer Coated Lithium Insertion Material for Metal-Air Battery
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Solution Overview
Problem
Current lithium/air batteries face challenges in reversibility and cycle life due to decomposition of aprotic electrolyte solvents in the presence of Li2O2 or reaction intermediates, limiting their high energy and power density.
Innovation Solution
An electrochemical cell design featuring a polymer coating on the lithium insertion material that acts as a barrier between the electrolyte solvent and Li2O2, reduced oxygen intermediates, and electrons, allowing the solvent to be separated from these components, with the polymer being permeable to lithium ions and oxygen while being impermeable to the solvent, electrons, and oxygen anions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If aprotic electrolyte solvents are used in lithium/air batteries, then high energy and power density is achieved, but decomposition occurs in the presence of Li2O2 or reaction intermediates, reducing reversibility and cycle life
Solution Approach 1:
A polymer coating is introduced as an intermediary layer between the aprotic electrolyte solvent and Li2O2/reaction intermediates. This coating allows lithium ion transport while preventing direct contact between the solvent and harmful species, thereby maintaining high energy density through aprotic solvents while improving cycle life by preventing decomposition
Solution Approach 2:
A thin polymer coating is formed on the lithium insertion material surface. This flexible film acts as a protective barrier that is permeable to lithium ions but impermeable to aprotic electrolyte solvents and reaction intermediates, enabling the system to maintain high energy density while achieving improved reversibility and cycle life
2Use of energy by moving object
If Li2O2 is formed as a discharge product in lithium/air batteries, then high theoretical specific energy is achieved, but decomposition of electrolyte solvent occurs, limiting reversibility
Solution Approach 1:
The polymer coating serves as a mediator that allows Li2O2 to form as the discharge product (maintaining high specific energy) while simultaneously preventing the electrolyte solvent from contacting and decomposing due to the presence of Li2O2 or its intermediates, thereby improving reversibility
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 design enhances the reversibility and cycle life of lithium/air cells by protecting the electrolyte solvent from Li2O2 and reaction intermediates, maintaining high energy and power density.
Implementation Method 1
the polymer being permeable to lithium ions and oxygen while being impermeable to the solvent, electrons, and oxygen anions
Implementation Method 2
acts as a barrier between the electrolyte solvent and Li2O2, reduced oxygen intermediates, and electrons
Data Source
AI summary
In accordance with one embodiment, an electrochemical cell includes a negative electrode including a form of lithium, a positive electrode spaced apart from the negative electrode and including an electron conducting matrix and a lithium insertion material wherein Li2O2 is formed as a discharge product, a separator positioned between the negative electrode and the positive electrode, an electrolyte including a salt, and a polymer coating on the lithium insertion material, the polymer coating permeable to lithium ions and impermeable to the electrolyte.