Nonaqueous Electrolyte Composition for Stable Battery Cycle Retention
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries using tripropanolamine borate or triethanolamine borate as additives exhibit low capacity retention and input/output retention rates during cycles, with increased triethanolamine borate leading to deteriorated initial input/output characteristics and decreased capacity retention.
Innovation Solution
Incorporating hexafluorophosphate and specific salts, such as fluorophosphates, fluorosulfonates, and imide salts, into the nonaqueous electrolytic solution, along with triethanolamine borate, to improve capacity and input/output retention rates by forming a uniform and electrochemically stable passivation layer on the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If triethanolamine borate is increased to improve input/output retention rate, then input/output retention rate increases, but initial input/output characteristics deteriorate and capacity retention rate decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing hexafluorophosphate and specific salt combinations (fluorophosphates, fluorosulfonates, imide salts) to modify the passivation layer properties. This allows achieving stable capacity retention (95% or higher after 500 cycles) and good input/output retention without the deterioration caused by excessive triethanolamine borate
Solution Approach 2:
The patent creates a composite electrolyte system combining hexafluorophosphate, specific salts, and controlled amounts of triethanolamine borate. This composite approach produces a passivation layer with both stability and conductivity properties, resolving the contradiction between retention rate improvement and initial performance maintenance
2Temperature
If tripropanolamine borate or triethanolamine borate is used as additive, then high-temperature storage characteristics improve, but capacity retention rate and input/output retention rate during cycles decrease
Solution Approach 1:
The patent merges multiple functional components (hexafluorophosphate for passivation layer formation, specific salts for electrochemical stability, and borate esters for high-temperature protection) into a single electrolyte system. This combination achieves both high-temperature storage characteristics and excellent cycle characteristics with capacity retention above 95% after 500 cycles
Solution Approach 2:
The passivation layer formed by hexafluorophosphate and specific salts acts as an intermediary between the electrode and the borate ester additive. This intermediary layer enables the borate ester to provide high-temperature stability without causing the side reactions that lead to poor cycle characteristics
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 significantly enhances capacity retention, input/output retention, and impedance characteristics, leading to improved cycle, high-temperature storage, and safety performance in power storage devices.
Implementation Method 1
Incorporating hexafluorophosphate and specific salts, such as fluorophosphates, fluorosulfonates, and imide salts, into the nonaqueous electrolytic solution, along with triethanolamine borate, to improve capacity and input/output retention rates by forming a uniform and electrochemically stable passivation layer on the negative electrode
Data Source
AI summary
Provided is a nonaqueous electrolytic solution having an excellent capacity retention rate and an excellent output retention rate during cycles. The nonaqueous electrolytic solution includes a nonaqueous solvent; a hexafluorophosphate (A); a compound (B) represented by the following formula (1) in which an arbitrary hydrogen atom bonded to a carbon atom may be substituted with a fluorine atom; and at least one salt (C) selected from the group consisting of fluorophosphates other than the hexafluorophosphate (A), fluorosulfonates, imide salts represented by MN(SO2F)2, wherein M represents an alkali metal, and oxalate salts.