Dual Passivating Agents for Lithium-Ion Cell Cycle Stability
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Solution Overview
Problem
Rechargeable batteries with lithium-containing cathode active materials exhibit limited cycle lifetimes due to decomposition and oxidation issues, necessitating improvements in cycle life and stability.
Innovation Solution
The use of electrochemical cells comprising a first passivating agent, such as an N—O compound, and a second passivating agent, like lithium difluoro(oxalato)borate, which interact to form layers on the electrodes, reducing decomposition and enhancing cycle life by preventing oxidation and promoting stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-containing cathode active materials are used to achieve high energy density, then energy density is improved, but cycle lifetime deteriorates due to decomposition and oxidation
Solution Approach 1:
The patent introduces passivating agents (first and second passivating agents) as intermediary substances that mediate between the lithium-containing cathode active material and the electrolyte. These passivating agents form protective layers on the cathode surface, preventing direct harmful interactions while allowing lithium ion transport, thus resolving the contradiction between high energy density and cycle lifetime
Solution Approach 2:
The patent employs composite passivating layer structures formed by multiple passivating agents with different chemical compositions and functions. The first passivating agent (e.g., N-O compound) and second passivating agent (e.g., lithium difluoro(oxalato)borate) work synergistically to create a multi-functional protective layer that simultaneously provides oxidation protection, decomposition prevention, and ion conductivity
2Power
If cathode active materials undergo electrochemical intercalation and oxidation processes, then charge-discharge capacity is improved, but decomposition occurs leading to reduced stability
Solution Approach 1:
The passivating agents are introduced into the electrolyte before cell operation to preemptively form protective layers on the cathode surface. This preliminary action prevents oxidation and decomposition during subsequent charge-discharge cycles, allowing the cathode material to undergo electrochemical intercalation processes without suffering from harmful side 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 combination of passivating agents significantly increases the cycle life of lithium-containing batteries by reducing decomposition and oxidation, allowing for higher capacity and longer operational life.
Implementation Method 1
cathode active material reduction and oxidation electrochemical processes generally involve lithium ions
Implementation Method 2
first passivating agent and a second passivating agent... interact to form layers on the electrodes, reducing decomposition and enhancing cycle life by preventing oxidation
Data Source
AI summary
Articles and methods involving electrochemical cells and/or electrochemical cell preproducts comprising passivating agents are generally provided. In certain embodiments, an electrochemical cell includes first and second passivating agents. In some embodiments, an electrochemical cell may include a first electrode comprising a first surface, a second electrode (e.g., a counter electrode with respect to the first electrode) comprising a second surface, a first passivating agent configured and arranged to passivate the first surface, and a second passivating agent configured and arranged to passivate the second surface.