Nonaqueous Li-Ion Electrolyte Additives for Lithium Plating Suppression
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Solution Overview
Problem
Lithium ion secondary batteries face issues with metallic lithium precipitation on electrodes, leading to capacity drops and internal short-circuits due to dendritic growth, necessitating a solution to render precipitated metallic lithium harmless.
Innovation Solution
A nonaqueous electrolyte solution for lithium ion secondary batteries containing a lithium salt, a nonaqueous solvent, an aromatic carboxylic acid compound, and an aryl halide compound, specifically benzoic acid or 2-naphthalene carboxylic acid combined with an aryl iodide, which suppresses metallic lithium precipitation by forming a coating film that immobilizes lithium carbonate on the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used, then lithium ion secondary batteries can operate, but metallic lithium precipitates on electrodes causing capacity drops and internal short-circuits
Solution Approach 1:
The patent introduces an aromatic carboxylic acid compound as an intermediary substance in the electrolyte solution that mediates between lithium ions and the electrode surface. This compound forms a protective interface layer that prevents direct contact between precipitated metallic lithium and the electrode, thereby eliminating the harmful effects of lithium precipitation while maintaining battery operation.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte solution by adding specific aromatic carboxylic acid compounds (such as benzoic acid, 2-naphthalene carboxylic acid) at controlled concentrations (0.01-100 mmol/L). This parameter modification alters the electrolyte's interaction with lithium ions, preventing dendritic growth and rendering precipitated lithium harmless through chemical passivation.
2Reliability
If aromatic carboxylic acid compound and aryl halide compound are added to the electrolyte solution, then metallic lithium precipitation is suppressed, but the electrolyte solution composition becomes more complex
Solution Approach 1:
The patent creates a composite electrolyte system by combining aromatic carboxylic acid compounds with aryl halide compounds (such as iodobenzene, 2-iodonaphthalene) in specific concentration ratios. This composite approach synergistically enhances the suppression of metallic lithium precipitation, where the two compounds work together to form a more effective protective layer than either compound alone, justifying the increased compositional 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 combination of aromatic carboxylic acid and aryl halide compounds effectively renders precipitated metallic lithium harmless, reducing capacity loss and preventing internal short-circuits, with optimal concentrations of these additives enhancing the suppression of metallic lithium precipitation.
Implementation Method 1
forming a coating film that immobilizes lithium carbonate on the negative electrode
Data Source
AI summary
Provided is a technology that allows precipitated metallic lithium to be rendered harmless in a lithium ion secondary battery. The nonaqueous electrolyte solution of a lithium ion secondary battery disclosed herein contains a lithium salt as an electrolyte salt, a nonaqueous solvent, and an aromatic carboxylic acid compound and an aryl halide compound, as additives.