High Voltage Lithium Ion Battery Electrolyte Corrosion Protection
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Solution Overview
Problem
Current lithium-ion batteries face challenges in achieving high energy density due to limitations in electrolyte materials, particularly in preventing corrosion of aluminum or stainless steel components at high operating voltages, which affects the stability and cycle life of the battery.
Innovation Solution
The development of a non-aqueous electrolyte for lithium-ion batteries that includes an imide salt, such as lithium bisfluorosulfonylimide (LiFSI), and a perchlorate salt, like lithium perchlorate (LiClO4), which is electrochemically stable over a wide voltage range, inhibiting corrosion of aluminum or stainless steel components and enhancing the battery's cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium-ion batteries use standard electrolyte materials, then the battery can operate at typical voltages, but the electrolyte causes corrosion of aluminum or stainless steel components at high operating voltages, reducing stability and cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using a specific mixture of cyclic carbonate (15-30 vol%), chain carbonate (70-85 vol%), and fluoroethylene carbonate (5-15 vol%). This parameter optimization enables the electrolyte to maintain stability at high voltages up to 4.5V while preventing corrosion of aluminum current collectors and stainless steel components.
Solution Approach 2:
The patent employs a composite electrolyte system combining multiple carbonate solvents (cyclic and chain) with fluoroethylene carbonate additive. This composite formulation creates a synergistic effect where the mixture provides both high-voltage stability and corrosion protection, overcoming the limitations of single-component electrolytes.
2Use of energy by moving object
If the battery operates at high voltage (up to 4.5V) to increase energy density, then more energy can be stored, but the electrolyte becomes less stable and causes increased corrosion
Solution Approach 1:
The patent optimizes the voltage operating range parameter to 3.0-4.5V, which is higher than conventional batteries. This is made possible by the specialized electrolyte composition that maintains stability at these elevated voltages, enabling higher energy density while preserving electrolyte integrity and preventing component corrosion.
Solution Approach 2:
The patent applies different functional components to different aspects of electrolyte performance: cyclic carbonate provides high-voltage stability, chain carbonate ensures low-temperature fluidity and ion conductivity, and fluoroethylene carbonate forms protective SEI layers. This local specialization of components enables the electrolyte to handle high-voltage operation reliably.
3Productivity
If the battery operates at high voltage, then higher discharge capacity per cycle is achieved, but corrosion of current collector components increases, reducing cycle life
Solution Approach 1:
The fluoroethylene carbonate component performs a preliminary protective action by forming stable solid electrolyte interphase (SEI) layers on aluminum current collectors and stainless steel components during initial cycles. This preliminary protection prevents subsequent corrosion during high-voltage operation, thereby extending cycle life while maintaining high discharge capacity.
Solution Approach 2:
The patent uses a small concentration (5-15 vol%) of fluoroethylene carbonate as a sacrificial protective agent. This component is consumed during initial cycles to form protective layers, sacrificing itself to protect the more valuable current collector components from corrosion, thereby extending the overall battery cycle life.
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 electrolyte system achieves electrochemical stability at voltages up to 4.5V, significantly reducing corrosion and maintaining high discharge capacity over multiple cycles, thereby improving the overall performance and longevity of lithium-ion batteries.
Implementation Method 1
the electrolyte is both chemically and electrochemically stable... the electrolyte is electrochemically stable over a wide voltage range, for example, a voltage range of about 3V to 4.5V... The electrolyte suppresses aluminum or stainless steel corrosion during its use in a lithium ion cell
Implementation Method 2
cycling the battery at room temperature over a wide range of voltage, for example, 3V to 4.5V... The cell cycles stably over a wide voltage range
Data Source
AI summary
A secondary high energy density lithium ion cell includes a cathode comprising a high voltage cathode active material, a lithium metal anode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises an imide salt with a fluorosulfonyl group and a perchlorate salt, wherein the electrolyte is electrochemically stable at operating voltages greater than 4.2V.