Non-aqueous Electrolyte Additives for High-Voltage Cell Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary cells face challenges in maintaining high-temperature storage characteristics and cycle characteristics, particularly when charged at high voltages, due to oxidative decomposition of the electrolyte and degradation issues related to ethylene carbonate content.
Innovation Solution
Incorporating 1,3-dioxane and a dinitrile compound as additives in the non-aqueous electrolyte, with ethylene carbonate content between 25% to 40% by volume, along with vinylene carbonate, to enhance both cycle and high-temperature storage characteristics without degrading cell performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-voltage charging (positive electrode potential exceeding 4.3V) is implemented to improve utilization of positive electrode active material, then cell capacity increases, but oxidative decomposition of electrolyte occurs
Solution Approach 1:
1,3-dioxane and dinitrile compounds are added to the electrolyte in advance to create a protective environment before high-voltage charging occurs. These substances pre-form stable films on the positive electrode surface that prevent oxidative decomposition during subsequent high-voltage charging, allowing the system to achieve high cell capacity without electrolyte degradation
Solution Approach 2:
The 1,3-dioxane and dinitrile compounds act as intermediary substances between the high-voltage charging process and the electrolyte. They intercept the oxidative stress generated during high-voltage charging and prevent it from attacking the main electrolyte components, thereby enabling high cell capacity while preventing harmful decomposition
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 synergistic effect of these additives improves cycle discharge capacity and high-temperature storage characteristics, maintaining excellent performance across multiple charge-discharge cycles and high-temperature conditions.
Implementation Method 1
Incorporating 1,3-dioxane and a dinitrile compound as additives in the non-aqueous electrolyte... the synergistic effect of these additives improves cycle discharge capacity and high-temperature storage characteristics
Implementation Method 2
a positive electrode having an active material capable of inserting and extracting lithium... a non-aqueous electrolyte containing a non-aqueous solvent and an electrolyte salt
Data Source
AI summary
A non-aqueous electrolyte secondary cell can be charged at a high voltage of 4.3V or more and has excellent cycle characteristics and excellent high-temperature storage characteristics. The cell includes positive and negative electrodes capable of inserting and extracting lithium, and a non-aqueous electrolyte. The non-aqueous electrolyte contains a non-aqueous solvent, 1,3-dioxane and a dinitrile compound additives, and an electrolyte salt. The non-aqueous solvent contains ethylene carbonate in the range of 25% to 40% by volume under the conditions of 25° C. and 1 atm.