Nonaqueous Electrolyte Solution Acid Suppression for Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries with nickel and silicon-based electrodes face degradation issues due to acid production from trace water in the electrolyte, leading to reduced cycle life and battery performance, especially under high temperature conditions.
Innovation Solution
A nonaqueous electrolyte solution containing specific compounds with nitrogen, sulfur, or oxygen atoms, but no disulfide bonds, is used as an additive to prevent acid production, maintaining high capacity density and stabilizing battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-containing materials are used as positive electrode active material to increase energy density, then battery capacity is improved, but acid production increases due to trace water reaction, leading to electrolyte degradation
Solution Approach 1:
The patent introduces a specific compound containing nitrogen and sulfur or oxygen atoms as an intermediary substance in the electrolyte. This compound mediates between the nickel-containing positive electrode material and trace water, preventing the direct reaction that produces acid. The compound acts as a buffer or scavenger that intercepts the harmful reaction pathway while allowing the beneficial electrochemical reactions to proceed.
Solution Approach 2:
The patent converts the harmful effect of trace water (which reacts with nickel materials to produce acid) into a beneficial outcome by introducing a compound that preferentially reacts with or stabilizes the trace water. The compound containing nitrogen and sulfur or oxygen atoms transforms the harmful water-nickel interaction into a controlled reaction that prevents acid generation while maintaining battery performance.
2Quantity of substance
If silicon-containing materials are used as negative electrode active material to increase theoretical capacity, then battery capacity is improved, but impedance increases due to acid content reaction with silicon surface, degrading battery characteristics
Solution Approach 1:
The compound containing nitrogen and sulfur or oxygen atoms serves as a protective intermediary between the acid content in the electrolyte and the silicon-containing negative electrode material. It forms a protective layer or complex on the silicon surface that prevents direct acid-silicon interaction, thereby maintaining low impedance and stable battery characteristics while preserving the high capacity benefits of silicon.
3Stability of the object's composition
If conventional electrolyte additives are used to improve high temperature storage characteristics, then storage stability is improved, but the influence on acid production and its effect on silicon negative electrode is not addressed
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by introducing a compound with specific atomic composition (nitrogen and sulfur or oxygen atoms). This parameter change fundamentally alters the electrolyte's interaction with acid and silicon surfaces, providing dual benefits of improved high-temperature storage stability and protection against acid-induced impedance increase on the silicon negative electrode.
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 solution effectively suppresses acid production and maintains battery capacity and cycle life, even under high temperature conditions, by using compounds like bis(dibutyldithiocarbamate)methylene or 2,5-dimercapto-1,3,4-thiadiazole in the electrolyte, which are added in specific concentrations to the nonaqueous electrolyte solution.
Implementation Method 1
when a compound comprising specific amounts of nitrogen atoms and sulfur atoms or oxygen atoms and having no disulfide bond in a molecule is used as an additive of an electrolyte solution, it is possible to maintain high capacity density under the high temperature condition
Implementation Method 2
the use of a nonaqueous electrolyte comprising boric acid triester to improve the high temperature storage characteristics and cycle characteristics of the lithium secondary battery
Data Source
AI summary
The present disclosure is directed to providing an electrolyte solution with a long cycle life by suppressing degradation of the battery characteristics under the high temperature condition. There is provided a nonaqueous electrolyte solution comprising a compound comprising 5 to 20 mass % of nitrogen atoms and 25 to 70 mass % of sulfur atoms or oxygen atoms in a molecule and having no disulfide bond in the molecule, wherein the compound comprises at least two sulfur atoms or oxygen atoms in the molecule.