Secondary Battery Pre-Charging Below Additive Reduction Voltage
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Solution Overview
Problem
Existing methods of pre-charging secondary batteries to lower the potential of the negative electrode before wetting with electrolyte result in non-uniform film formation due to additive reactions, leading to reduced battery lifetime and potential failure.
Innovation Solution
A method involving deriving the reduction reaction voltage of electrolyte additives, performing pre-charging with a termination voltage below this threshold, and a pre-aging process to ensure uniform SEI film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-charging is performed before wetting with electrolyte to lower negative electrode potential, then metal foreign substance elution is prevented, but additive reduction reaction occurs forming non-uniform film
Solution Approach 1:
The patent applies preliminary action by performing pre-charging before complete wetting to lower the negative electrode potential and prevent metal foreign substance elution. This preliminary action addresses the reliability issue by establishing a protective potential state before the electrolyte fully penetrates the electrode pores, preventing dendrite formation and low voltage failure.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the charging termination voltage to be below the reduction potential of metal foreign substances but above the reduction potential of electrolyte additives. This parameter optimization allows the system to achieve the beneficial effect of preventing metal elution while avoiding the harmful side effect of additive reduction and non-uniform film formation.
2Manufacturing precision
If pre-charging is delayed until after complete wetting to avoid additive reaction, then uniform SEI film forms, but metal foreign substances may elute and cause low voltage failure
Solution Approach 1:
The patent performs the critical action of potential lowering through pre-charging as a preliminary step before complete wetting occurs. This timing is crucial because it establishes the protective potential state on the negative electrode surface before the electrolyte additives can cause harmful reduction reactions, thereby preventing both metal elution and non-uniform film formation.
Solution Approach 2:
The patent optimizes the charging termination voltage parameter to fall within a specific range that is below the reduction potential of metal foreign substances (such as iron at 2.59V or nickel at 2.78V) but above the reduction potential of electrolyte additives. This precise parameter control enables selective prevention of metal reduction while allowing controlled additive reaction only after uniform wetting.
3Manufacturing precision
If charging voltage is set high to ensure complete wetting before pre-charging, then uniform film forms, but metal foreign substances oxidize and elute
Solution Approach 1:
The patent applies preliminary action by initiating pre-charging before complete wetting to lower the negative electrode potential and prevent metal foreign substance oxidation and elution. This timing prevents the harmful sequence where high voltage causes metal oxidation during the wetting process.
Solution Approach 2:
The patent changes the voltage parameter strategy by using a charging termination voltage below the metal reduction potential during pre-charging, rather than using high voltage to ensure wetting. This parameter change prevents metal oxidation and elution while still achieving sufficient wetting through the controlled pre-charging process.
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
Prevents low voltage failure and ensures uniform SEI film formation by suppressing additive reactions on the negative electrode, thereby improving battery performance.
Implementation Method 1
some additives contained in the electrolyte may cause a reduction reaction on a surface of the negative electrode during the pre-charging to form a non-uniform film on the surface of the negative electrode
Implementation Method 2
After the electrolyte is injected, the electrolyte gradually wets the inside of pores of an electrode
Data Source
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AI summary
Provided is a method of activating a secondary battery, which includes an operation of deriving a reduction reaction voltage according to an electrolyte additive, a pre-charging operation of pre-charging the secondary battery into which an electrolyte containing the electrolyte additive is injected, and a pre-aging operation of wetting an electrode assembly accommodated in the secondary battery with the injected electrolyte and aging the electrode assembly, wherein a charging termination voltage in the pre-charging operation is less than the reduction reaction voltage.