High-Mn Battery Electrolyte With FEC for Cycle Stability
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Solution Overview
Problem
High proportions of manganese in positive electrode active materials in lithium batteries lead to poor cycling and storage performance due to manganese dissolution, which damages the solid electrolyte interphase (SEI) on negative electrodes.
Innovation Solution
Incorporating fluoroethylene carbonate (FEC) in the electrolyte at specific concentrations and ratios with the unit reaction area of the positive electrode active material, along with other additives like vinylene carbonate and dimethyl carbonate, to form protective layers on both electrodes, reducing manganese dissolution and enhancing battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the proportion of manganese in positive electrode active materials is increased to decrease costs, then manufacturing cost is reduced, but cycling performance and storage performance deteriorate due to manganese dissolution
Solution Approach 1:
The patent introduces fluoroethylene carbonate (FEC) as an intermediary substance in the electrolyte that mediates between the positive and negative electrodes. FEC forms protective films on both electrodes, preventing direct harmful interactions and manganese dissolution, thereby resolving the contradiction between using high-manganese cost-effective materials and maintaining battery performance reliability
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding FEC at specific concentrations (0.01%-5% by mass) and controlling the ratio of FEC to unit reaction area (0.0006≤a/c≤6.25). This parameter optimization enables the electrolyte to form effective protective layers that prevent manganese dissolution while maintaining cost-effectiveness of high-manganese cathode materials
2Ease of manufacture
If the proportion of manganese in positive electrode active materials is increased to decrease costs, then manufacturing cost is reduced, but manganese dissolution increases damaging the SEI film on negative electrodes
Solution Approach 1:
FEC acts as a protective intermediary that forms stable films on the negative electrode SEI and positive electrode surface, preventing manganese ions from dissolving and migrating to the negative electrode. This intermediary layer eliminates the harmful effect of manganese dissolution while allowing the use of cost-effective high-manganese cathode materials
Solution Approach 2:
The patent applies preliminary protective action by having FEC form stable protective films on the electrodes before manganese dissolution can occur. This preliminary film formation prevents the harmful dissolution process from initiating, thereby protecting the battery system while maintaining cost benefits of high-manganese materials
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
This approach significantly improves the cycling and storage performance of lithium batteries with high manganese content in positive electrode materials, maintaining performance while reducing costs without compromising battery stability.
Implementation Method 1
the electrolyte includes fluoroethylene carbonate... the positive electrode active material has a unit reaction area c... a and c satisfy the following relationship: 0.0006≤a/c≤6.25
Implementation Method 2
Incorporating fluoroethylene carbonate (FEC) in the electrolyte at specific concentrations and ratios with the unit reaction area of the positive electrode active material, along with other additives like vinylene carbonate and dimethyl carbonate, to form protective layers on both electrodes, reducing manganese dissolution
Data Source
AI summary
An electrolyte includes fluoroethylene carbonate, where a percentage a of the fluoroethylene carbonate is 0.01% to 5% based on mass of the electrolyte; the positive electrode includes a positive electrode active material, where the positive electrode active material contains element Mn, and a percentage of the element Mn is greater than or equal to 15% based on mass of the positive electrode active material; and the positive electrode active material has a unit reaction area c measured in m2/cm2, where a and c satisfy the following relationship: 0.0006≤a/c≤6.25, and the unit reaction area is a product of a weight W of the positive electrode active material per unit area and a specific surface area BET of the positive electrode active material.