DOPO-Based Electrolyte Additives for High-Voltage Cathode Stability
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Solution Overview
Problem
High voltage Li-ion batteries face stability issues due to electrochemical oxidation of cathode materials, leading to structural breakdown and capacity loss, especially at extreme temperatures, where the Solid Electrolyte Interface (SEI) and Cathode Electrolyte Interface (CEI) stability are compromised, necessitating improved electrolyte components for safe and efficient cycling.
Innovation Solution
The use of DOPO-based molecules as electrolyte additives in combination with aprotic organic solvents and metal salts, incorporating silyl-based groups or unsaturated terminal groups, forms a stable silicon-containing film on electrodes, preventing electrolyte-electrode reactions and enhancing long-term performance by forming a protective film and improving solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage cathode materials are used to increase energy density, then battery capacity and energy density are improved, but cathode material stability deteriorates due to electrochemical oxidation
Solution Approach 1:
The patent introduces DOPO-based additives as intermediary substances between the high voltage cathode material and the electrolyte. These additives form protective interface films that mediate the interaction, preventing direct electrochemical oxidation of the cathode material while allowing lithium ion transport, thus resolving the contradiction between achieving high energy density and maintaining cathode stability
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific DOPO-based derivatives with different functional groups (silyl, phosphonic acid, etc.). This changes the interface formation characteristics and electrochemical stability window, enabling the system to operate at higher voltages without cathode degradation, thereby simultaneously achieving higher energy density and maintaining stability
2Ease of operation
If traditional carbonate-based electrolytes are used, then lithium ion transport is enabled, but SEI and CEI layer stability is compromised at high temperatures
Solution Approach 1:
The patent creates a composite electrolyte system combining traditional carbonate-based solvents (for lithium ion transport) with DOPO-based additive molecules (for interface stabilization). This composite approach allows the electrolyte to simultaneously provide efficient ion conduction through the carbonate component and form stable, temperature-resistant protective films through the DOPO component, resolving the contradiction between ease of operation and reliability at high temperatures
3Reliability
If electrolyte additives are added to stabilize cathode, then cathode stability is improved, but electrolyte complexity increases
Solution Approach 1:
The patent designs DOPO-based molecules that perform multiple functions simultaneously: they form protective films on the cathode surface, stabilize the electrolyte at high temperatures, enable high voltage operation, and maintain good lithium ion transport. This multi-functionality reduces the need for multiple separate additives, thereby improving cathode stability without proportionally increasing electrolyte complexity
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 DOPO-based electrolytes enhance the cycle life and storage characteristics of Li-ion batteries at high voltages and temperatures, reducing gas generation and maintaining performance by stabilizing the cathode and forming a protective film on electrodes.
Implementation Method 1
electrochemical oxidation of the cathode materials
Implementation Method 2
forms a stable silicon-containing film on electrodes
Implementation Method 3
The shuttling of positive and negative ions between the battery electrodes is the main function of the electrolyte
Implementation Method 4
an aprotic organic solvent; and a metal salt
Data Source
AI summary
An electrolyte containing a DOPO-based molecule; an aprotic organic solvent; and a metal salt and an electrochemical energy storage device containing the electrolyte is disclosed.