Lithium-Ion Battery Electrolyte Aging for Low-Gas Capacity Retention
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Solution Overview
Problem
The existing methods for producing lithium-ion batteries using electrolyte solutions with lithium bis(oxalato)borate (LiBOB) and vinylene carbonate (VC) result in excessive gas generation during high-temperature storage due to the inhibition of VC degradation by LiBOB, leading to compromised capacity retention.
Innovation Solution
A method involving the injection of an electrolyte solution containing both LiBOB and VC into a lithium-ion battery, followed by initial charging and aging, where the mass fractions of both LiBOB and VC are reduced to less than 0.10% by degrading them during a process involving adjusting the state of charge and storing the battery at elevated temperatures, thereby balancing capacity retention and gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiBOB and VC are both added to the electrolyte solution, then capacity retention during high-temperature storage is improved, but gas generation increases due to VC remaining in large amounts
Solution Approach 1:
The patent applies preliminary action by performing an initial charging process before normal use that promotes the degradation of both LiBOB and VC. This preliminary degradation step reduces VC content to below 0.10 mass% before the battery enters service, preventing excessive gas generation during high-temperature storage while preserving the protective film benefits for capacity retention.
Solution Approach 2:
The patent utilizes parameter changes by controlling the initial charging conditions (voltage, temperature, time) to accelerate the degradation of LiBOB and VC. By adjusting these parameters, the electrolyte composition is transformed from containing significant amounts of both additives to having degraded residues below 0.10 mass%, resolving the contradiction between film formation and gas generation.
2Object-generated harmful factors
If VC is not present in the electrolyte solution, then gas generation during high-temperature storage decreases, but capacity retention deteriorates
Solution Approach 1:
Rather than completely removing VC, the patent applies preliminary action through initial charging to degrade VC to a controlled residual level (below 0.10 mass%). This approach maintains enough VC to form protective films for capacity retention while eliminating excessive VC that would cause gas generation, achieving a balance that complete removal cannot provide.
Solution Approach 2:
The patent applies local quality by creating different VC concentration zones: during initial charging, VC is allowed to concentrate and form protective films on electrode surfaces, while the bulk electrolyte VC content is reduced to below 0.10 mass% through controlled degradation. This spatial and temporal differentiation resolves the contradiction between needing VC for film formation and avoiding VC for gas generation.
3Object-generated harmful factors
If LiBOB is not present in the electrolyte solution, then gas generation decreases, but capacity retention during high-temperature storage deteriorates
Solution Approach 1:
The patent applies preliminary action by using initial charging to promote LiBOB degradation to below 0.10 mass% residual content. This preliminary degradation eliminates LiBOB's role in inhibiting VC breakdown (which would reduce gas generation) while preserving the initial film-forming benefits, and simultaneously reduces VC to low levels to prevent excessive gas generation during storage.
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 approach effectively decreases gas generation during high-temperature storage while maintaining a desired level of capacity retention by ensuring both LiBOB and VC are degraded to low concentrations post-aging.
Implementation Method 1
the formation of the film is caused by reduction and degradation of each of LiBOB and VC on the surface of the negative electrode during initial charging
Implementation Method 2
storing the lithium-ion battery in an environment at a temperature of 60° C. or more for 10 hours or more
Data Source
AI summary
(A) An electrolyte solution containing lithium bis(oxalato)borate and vinylene carbonate is injected into a lithium-ion battery. (B) Initial charging is performed. (C) Aging is performed. During the aging, lithium bis(oxalato)borate and vinylene carbonate contained in the electrolyte solution are degraded. After the aging, in the electrolyte solution, a mass fraction of lithium bis(oxalato)borate is less than 0.10% and a mass fraction of vinylene carbonate is less than 0.10%.