High Voltage Li-Ion Battery Electrolyte Additives
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Solution Overview
Problem
Lithium ion batteries operating at high voltages experience decreased cycle life due to oxidative instability and irreversible changes, limiting their capacity and power output.
Innovation Solution
The use of a lithium-rich layered metal oxide composition with a specific electrolyte formulation, including LiPF6 or LiBF4, ethylene carbonate, and a lithium salt additive, stabilizes the battery performance by preventing oxidative degradation and improving cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage operation is implemented to increase capacity and power output, then energy density and power are improved, but cycle life decreases due to oxidative instability
Solution Approach 1:
The patent introduces a mediator substance (electrolyte additive) that forms a protective interface layer between the electrode and electrolyte. This intermediary layer prevents direct harmful interactions while allowing beneficial electrochemical reactions to proceed, thereby enabling high voltage operation without sacrificing cycle life.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives at controlled concentrations. This parameter modification alters the electrochemical stability window and oxidation resistance of the system, allowing operation at higher voltages while maintaining reliability.
2Power
If high voltage operation is implemented to increase power output, then power is improved, but oxidative degradation increases reducing reliability
Solution Approach 1:
The patent converts the harmful oxidative effect into a beneficial protective mechanism. The electrolyte additive undergoes controlled oxidation to form a stable protective layer that prevents further oxidative degradation of the electrode materials, thereby enabling high power output without sacrificing reliability.
Solution Approach 2:
The electrolyte additive acts as an intermediary that sacrifices itself through controlled oxidation to protect the electrode from harmful oxidative degradation. This mediator absorbs the harmful oxidative effect while maintaining the electrochemical performance needed for high power output.
3Device complexity
If conventional electrolytes are used in high voltage batteries, then device complexity is minimized, but cycling stability deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding specific substances at defined concentrations. This parameter change enhances the electrochemical stability and oxidation resistance of the electrolyte, thereby improving cycling stability while maintaining relatively simple device architecture.
Solution Approach 2:
The patent creates a composite electrolyte system by combining conventional electrolyte components with specialized additives. This composite formulation synergistically improves cycling stability while maintaining the basic structure and simplicity of conventional battery design.
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 described electrolyte composition enhances the cycling performance of high voltage lithium ion batteries, maintaining capacity and power output over a larger number of cycles, thereby extending the battery's lifespan.
Implementation Method 1
The electrolyte comprises LiPF6 and/or LiBF4, a solvent comprising ethylene carbonate and a liquid organic solvent, and an electrolyte stabilizing additive... stabilizes the battery performance by preventing oxidative degradation
Implementation Method 2
Lithium ion secondary batteries generally have a negative electrode material that intercalates lithium... The positive electrode comprises a lithium intercalation compound, and the negative electrode comprises a lithium intercalation/alloying compound
Data Source
AI summary
Desirable electrolyte compositions are described that are suitable for high voltage lithium ion batteries with a rated charge voltage at least about 4.45 volts. The electrolyte compositions can comprise ethylene carbonate and solvent composition selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, γ-valerolactone or a combination thereof. The electrolyte can further comprise a stabilization additive. The electrolytes can be effectively used with lithium rich positive electrode active materials.