Nonaqueous Battery Electrolyte Additives for Low-Temperature Resistance
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Solution Overview
Problem
Nonaqueous electrolyte batteries using unsaturated bond-containing silicon compounds exhibit high internal resistance at low temperatures, which hinders improved input/output characteristics, and existing additives face issues like carcinogenicity and gas generation.
Innovation Solution
An electrolyte solution containing a nonaqueous organic solvent, an ionic salt, and a silicon compound with unsaturated bonds and aromatic rings, along with a specific additive obtained by replacing an ethenyl group with an ethyl group, is used to decrease the battery's resistance at low temperatures without impairing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unsaturated bond-containing silicon compounds are used as additives in nonaqueous electrolyte batteries, then cycle characteristics are improved, but internal resistance increases at low temperatures
Solution Approach 1:
The patent modifies the chemical structure of silicon compounds by introducing aromatic rings and specific substituent groups (formula 1) to change the properties of the additive. This structural parameter change allows the compound to form SEI films with different characteristics that reduce low-temperature resistance while maintaining cycle stability.
Solution Approach 2:
The patent uses composite electrolyte solutions containing multiple components: the specific silicon compound (formula 1), its derivative (formula 2), and other conventional additives like vinylene carbonate. This composite approach combines the benefits of different materials to achieve both low resistance and good cycle characteristics.
2Reliability
If conventional additives like vinylene carbonate are used to form SEI films, then cycle characteristics improve, but input/output characteristics deteriorate at low temperatures
Solution Approach 1:
The patent changes the chemical parameters of SEI-forming additives by using silicon compounds with aromatic rings and specific substituent groups instead of conventional vinylene carbonate. This parameter change results in SEI films with lower resistance that maintain both cycle stability and power characteristics at low temperatures.
3Reliability
If existing additives like 1,3-propenesultone are used for SEI formation, then effective coating is achieved, but carcinogenicity issues arise
Solution Approach 1:
The patent replaces hazardous additives like 1,3-propenesultone with silicon compounds that are environmentally friendly and non-carcinogenic. The silicon-based additives achieve the same SEI formation function without the harmful biological effects, making them safer for battery applications.
4Reliability
If oxalato complexes of boron or phosphorus are used as additives, then SEI formation is improved, but battery swelling occurs due to gas generation
Solution Approach 1:
The patent removes the problematic oxalato complex components from the electrolyte formulation and replaces them with silicon compounds. This extraction eliminates the source of gas generation and battery swelling while preserving the beneficial SEI formation capabilities through alternative chemical mechanisms.
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 reduces the absolute value of resistance by more than 1% at -20°C without compromising cycle characteristics, enhancing the battery's low-temperature performance.
Implementation Method 1
when a lithium cation is inserted in the negative electrode during initial charging, a reaction occurs between the negative electrode and the lithium cation or between the negative electrode and the electrolyte solvent. As a result of the reaction, a coating film containing lithium oxide, lithium carbonate or lithium alkylcarbonate as a predominant component is formed on a surface of the negative electrode.
Implementation Method 2
Electrolyte solutions for lithium nonaqueous electrolyte batteries in which fluorine-containing electrolytes such as lithium hexafluorophosphate (hereinafter referred to as 'LiPF6'), lithium bis(fluorosulfonyl)imide (hereinafter referred to as 'LiFSI') and lithium tetrafluoroborate (hereinafter referred to as 'LiBF4') as solutes are dissolved in solvents such as cyclic carbonate, chain carbonate and ester
Data Source
AI summary
An electrolyte solution for a nonaqueous electrolyte battery according to the present invention includes the following components: (I) a nonaqueous organic solvent; (II) an ionic salt as a solute; (III) at least one additive compound represented by the general formula (1); and (IV) at least one additive compound represented by the general formula (2), wherein the concentration of the component (IV) is 0.05 to 25.0 mass % with respect to 100 mass % of the component (III)where R1 are each independently a substituent group having at least one kind selected from unsaturated bond and aromatic ring.