Non-aqueous Electrolyte Battery Negative Electrode Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries using non-aqueous electrolyte solutions with oxalatoborate-based compounds initially exhibit higher negative electrode resistance, which increases with use, leading to decreased battery performance.
Innovation Solution
A method to modify the layer formed by the oxalatoborate-based compound on the negative electrode by adjusting the mB/mA ratio and incorporating a difluorophosphate salt in the electrolyte solution, reducing initial resistance and suppressing resistance increase with use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxalatoborate-based compound is used in the non-aqueous electrolyte solution, then the durability of the secondary battery is improved, but the initial negative electrode resistance increases
Solution Approach 1:
The patent combines oxalatoborate-based compound and difluorophosphate-based compound in the non-aqueous electrolyte solution to form a composite protective layer on the negative electrode. This composite layer integrates the durability-enhancing properties of oxalatoborate with the resistance-reducing properties of difluorophosphate, resolving the contradiction between improved durability and reduced initial resistance
Solution Approach 2:
The patent optimizes the concentration ratio of oxalatoborate-based compound to difluorophosphate-based compound in the electrolyte solution. By adjusting these parameters (concentrations ranging from 0.01-0.5 mol/kg for oxalatoborate and 0.01-1.0 mol/kg for difluorophosphate), the patent achieves the desired balance between durability and initial resistance characteristics
2Duration of action of stationary object
If an oxalatoborate-based compound is used in the non-aqueous electrolyte solution, then the increase in negative electrode resistance with use is suppressed, but the initial negative electrode resistance is higher
Solution Approach 1:
The difluorophosphate-based compound acts as an intermediary that modifies the protective layer formed by oxalatoborate-based compound. This intermediary substance reduces the resistance characteristics of the layer while maintaining the durability benefits, effectively mediating between resistance stability and initial resistance levels
Solution Approach 2:
The patent creates a protective layer with non-uniform composition on the negative electrode surface. The layer contains both oxalatoborate decomposition products (providing durability) and difluorophosphate decomposition products (providing low resistance), with the local composition optimized to achieve both resistance stability and low initial resistance
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 modified non-aqueous electrolyte secondary battery achieves low initial resistance and maintains performance over time, suitable for use in vehicles like plug-in hybrid and electric vehicles.
Implementation Method 1
during initial charging of the secondary battery the oxalatoborate-based compound decomposes to form a layer on the negative electrode active material
Implementation Method 2
the negative electrode comprising the layer exhibited a low initial resistance and an increase in the resistance with use was effectively suppressed
Data Source
AI summary
This invention provides a method for producing a non-aqueous electrolyte secondary battery. The method comprises constructing a battery cell that comprises a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and a non-aqueous electrolyte solution comprising a non-aqueous solvent and an oxalatoborate-based compound. The method further comprises charging the battery cell to form on the negative electrode a layer that is derived from the oxalatoborate-based compound and comprises boron and oxalate ions. The method further comprises carrying out a modification treatment to increase the ratio of number of moles mB of boron to number of moles mA of oxalate ions in the layer.