Lithium Battery Electrolyte Additive for Stable High-Temperature SEI
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Solution Overview
Problem
Lithium batteries face challenges in maintaining high energy density, stability, and lifespan due to issues with the formation of a high-resistance solid electrolyte interface (SEI) layer and side reactions during charging and discharging, particularly at high temperatures.
Innovation Solution
Incorporating a bicyclic sulfate-based compound in the organic electrolytic solution, along with lithium transition metal oxides of varying particle sizes, to form a stable and durable SEI layer that suppresses side reactions and enhances battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytic solutions are used, then the battery can operate, but a high-resistance SEI layer forms at high temperatures increasing internal resistance and reducing discharge capacity
Solution Approach 1:
The patent introduces a bicyclic sulfate-based compound as an intermediary substance in the electrolytic solution. This compound acts as a mediator that preferentially reacts to form a protective SEI layer, preventing direct harmful interactions between the electrolyte and electrode at high temperatures. The bicyclic sulfate compound serves as a sacrificial intermediary that forms a stable interface layer, reducing internal resistance and improving high-temperature stability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolytic solution by incorporating specific bicyclic sulfate-based compounds with defined molecular structures (Formula 1). This parameter change in the electrolyte composition alters the SEI layer formation characteristics, enabling the system to maintain low internal resistance and high discharge capacity at elevated temperatures where conventional electrolytes fail.
2Duration of action of moving object
If conventional electrolytic solutions are used, then the battery can function, but side reactions occur reducing discharge capacity and lifespan
Solution Approach 1:
The bicyclic sulfate-based compound serves as a protective intermediary that forms a stable SEI layer on the electrode surface. This intermediary layer prevents direct contact and harmful side reactions between the electrolytic solution and electrode materials, thereby preserving discharge capacity and extending battery lifespan by eliminating parasitic energy loss pathways.
Solution Approach 2:
The patent converts the potentially harmful side reactions into a beneficial process by designing the bicyclic sulfate compound to undergo controlled reduction and form a protective SEI layer. What would normally be harmful side reactions are redirected to form a beneficial protective interface that enhances long-term stability and prevents further degradation reactions.
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 modified SEI layer improves discharge capacity, lifespan, and high-temperature stability by blocking direct contact between the organic solvent and electrodes, resulting in increased reversibility and stability of lithium ion intercalation/deintercalation.
Implementation Method 1
the bicyclic sulfate-based compound reduces the sulfate ester group and forms a durable SEI layer
Implementation Method 2
improving the stability of the protection layer on the cathode
Data Source
AI summary
A lithium battery includes a cathode including a cathode active material; an anode including an anode active material; and an organic electrolytic solution between the cathode and the anode, wherein the cathode active material includes a first lithium transition metal oxide and a second lithium transition metal oxide, the first lithium transition metal oxide and the second lithium transition metal oxide have different particle diameters, the second lithium transition metal oxide includes primary particles having a particle diameter of about 1 μm or more, and the organic electrolytic solution includes a first lithium salt, an organic solvent, and a bicyclic sulfate-based compound represented by Formula 1 below: