LiBOB LiPF2O2 Electrolyte Concentration for Battery Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs) face challenges in maintaining performance across various environments, particularly in low-temperature conditions and requiring improved cycling characteristics without degrading driving performance.
Innovation Solution
A method of manufacturing nonaqueous electrolyte secondary batteries involves forming an electrode assembly with a positive and negative electrode plate separated by a separator, using a nonaqueous electrolyte containing lithium bis(oxalato)borate (LiBOB) and lithium difluorophosphate (LiPF2O2), where the concentration of LiBOB is higher than LiPF2O2 before charge and discharge, and lower after, to enhance cycling and low-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiBOB concentration is increased to improve cycling characteristics, then protective film formation is enhanced, but low-temperature discharge characteristics deteriorate
Solution Approach 1:
The patent changes the concentration parameter of LiBOB dynamically - initially high (0.01-0.5 mol/L) to form protective film, then reduced (0.001-0.1 mol/L) to improve low-temperature characteristics. This temporal parameter change resolves the contradiction between cycling characteristics and low-temperature performance.
Solution Approach 2:
The patent applies preliminary action by forming the protective film through high LiBOB concentration during initial cycles before normal operation. This preliminary film formation enables subsequent use of lower LiBOB concentration, achieving both protective film benefits and low-temperature performance.
2Temperature
If LiPF2O2 is added to improve low-temperature characteristics, then low-temperature discharge characteristics are enhanced, but cycling characteristics deteriorate
Solution Approach 1:
The patent dynamically adjusts the LiPF2O2 concentration parameter - initially low (0.001-0.05 mol/L) to maintain cycling characteristics, then increased (0.01-0.5 mol/L) to enhance low-temperature performance. This temporal variation resolves the contradiction between the two performance aspects.
Solution Approach 2:
The patent employs periodic action by alternating between different LiPF2O2 concentration levels during charge-discharge cycles. High concentration periods improve low-temperature characteristics while low concentration periods maintain cycling characteristics, achieving both benefits through periodic variation.
3Reliability
If excessive LiBOB is added to ensure sufficient protective film, then cycling characteristics improve, but lithium salt concentration becomes excessive affecting overall performance
Solution Approach 1:
The patent optimizes the LiBOB concentration parameter within a specific range (0.01-0.5 mol/L initially, then 0.001-0.1 mol/L) to achieve sufficient protective film formation while preventing excessive lithium salt concentration. This controlled parameter adjustment resolves the contradiction between film formation and overall performance.
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
This configuration improves the cycling and low-temperature characteristics of the batteries by maintaining a sufficient protective film on the negative electrode while preventing excessive lithium salt concentration, leading to enhanced performance and durability.
Implementation Method 1
When LiBOB is added to the nonaqueous electrolyte, a covering (SEI) of decomposition products is formed on the surface of a negative electrode active material and serves as a protective film for the negative electrode active material
Implementation Method 2
The method includes: forming an electrode assembly including a positive electrode plate and a negative electrode plate disposed with a separator interposed therebetween; arranging the electrode assembly and a nonaqueous electrolyte containing LiBOB (lithium bis(oxalato)borate) and LiPF2O2 (lithium difluorophosphate) inside an outer body; and configuring the concentration of the LiBOB to be larger than that of the LiPF2O2 and to be smaller than that of the LiPF2O2 by charge and discharge
Data Source
AI summary
Provided is a method of manufacturing a nonaqueous electrolyte secondary battery. The method includes: forming an electrode assembly including a positive electrode plate and a negative electrode plate disposed with a separator interposed therebetween; arranging the electrode assembly and a nonaqueous electrolyte containing LiBOB (lithium bis(oxalato)borate) and LiPF2O2 (lithium difluorophosphate) inside an outer body; and configuring the concentration of the LiBOB to be larger than that of the LiPF2O2 and to be smaller than that of the LiPF2O2 by charge and discharge.