Silicon-Containing Electrolyte Additives for High-Voltage Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion secondary batteries with high-voltage positive electrodes face oxidative decomposition of carbonate solvents, leading to reduced cycle life, and existing countermeasures are inadequate.
Innovation Solution
An electrolyte comprising a non-aqueous solvent, lithium salt, and specific compounds, such as those represented by certain formulas, is used to enhance the cycle life of high-voltage lithium-ion secondary batteries, including lithium salts with boron atoms and compounds with silicon atoms, which improve ion conductivity and chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-potential positive electrode is used to increase battery voltage and energy density, then the energy density is improved, but the carbonate solvent undergoes oxidative decomposition leading to reduced cycle life
Solution Approach 1:
A silicon-containing compound is introduced as an intermediary substance in the electrolyte. This compound acts as a mediator that prevents direct contact and reaction between the high-potential positive electrode and the carbonate solvent, thereby suppressing oxidative decomposition while maintaining high voltage operation and extending battery cycle life
Solution Approach 2:
The chemical composition of the electrolyte is modified by incorporating a silicon-containing compound. This parameter change in the electrolyte's molecular structure provides enhanced oxidation resistance, enabling the system to withstand high-potential operation without solvent decomposition, thus resolving the contradiction between energy density and cycle life
2Reliability
If conventional electrolyte additives are used to suppress oxidative decomposition, then cycle life is improved, but ion conductivity and battery performance are insufficient
Solution Approach 1:
The chemical structure of the electrolyte additive is changed from conventional options to a silicon-containing compound. This structural parameter change provides dual benefits: the silicon-containing compound offers superior oxidation resistance to extend cycle life, while simultaneously maintaining excellent ion conductivity, thus resolving the contradiction between reliability and power
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 proposed electrolyte enables lithium-ion secondary batteries to operate at high voltages with extended cycle life and improved ion conductivity, addressing the oxidative decomposition issue and enhancing battery performance.
Implementation Method 1
excellent lithium-ion conductivity at a voltage of around 4 V
Implementation Method 2
good balance between oxidation resistance and reduction resistance
Data Source
Figure 1
AI summary
An electrolyte containing a non-aqueous solvent, a lithium salt (A) and at least one compound (B) selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2) and a compound having a constitutional unit represented by the following formula (3a) and a constitutional unit represented by the following formula (3b).