Secondary Battery Pre-Lithiation Using Over-Lithiated Cathodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods of pre-lithiating negative electrodes in lithium secondary batteries face instability due to phase changes and reverse potential issues in over-lithiated positive electrodes, leading to unstable charging and discharging and reduced capacity and cycle lifetime.
Innovation Solution
A method involving electrochemical charging of a pre-lithiation cell with a lithium manganese-based oxide positive electrode, followed by separating the over-lithiated positive electrode and subjecting the secondary battery to first and second charging steps at different voltages to stabilize the positive electrode and transfer lithium to the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the positive electrode is over-lithiated to pre-lithiate the negative electrode, then the capacity and cycle lifetime are improved, but the positive electrode undergoes phase change and potential instability causing unstable charging and discharging
Solution Approach 1:
The patent applies preliminary action by over-lithiating the positive electrode before assembling the secondary battery. This pre-lithiation process adds extra lithium to the positive electrode, which compensates for the irreversible lithium consumption that occurs during initial charging of the negative electrode, thereby improving cycle lifetime while maintaining charging-discharging stability through controlled voltage parameters
Solution Approach 2:
The patent utilizes parameter changes by controlling the voltage range during over-lithiation of the positive electrode. By maintaining the voltage within a specific range (3.0-4.3V) and adjusting charging parameters, the patent achieves sufficient lithium excess to compensate for negative electrode lithium consumption while preventing phase changes and potential instability in the positive electrode material
2Reliability
If lithium metal is used to pre-lithiate the negative electrode, then the capacity reduction is prevented, but the handling and management become difficult due to instability
Solution Approach 1:
The patent uses an intermediary approach by employing a lithium salt-containing solution as a mediator between lithium metal and the negative electrode. The lithium salt solution allows controlled lithium deposition on the negative electrode surface without requiring direct handling of reactive lithium metal, thus preventing capacity reduction while significantly improving safety and ease of operation
Solution Approach 2:
The patent employs a disposable lithium salt-containing solution that can be easily handled and disposed of after use. This solution serves as a temporary carrier for lithium transfer, enabling pre-lithiation without the need for complex lithium metal handling infrastructure, thereby improving ease of operation while maintaining negative electrode stability
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 stabilizes the positive electrode phase, improves initial efficiency, and enhances the lifetime characteristics of the negative electrode by compensating for irreversible capacity through controlled lithium transfer.
Implementation Method 1
intercalating lithium into the positive electrode
Implementation Method 2
lithium is transferred from the over-lithiated positive electrode to the negative electrode
Implementation Method 3
the phase change, damage, and performance degradation of the positive electrode active material may occur
Data Source
AI summary
A method of manufacturing a secondary battery, which includes: electrochemically charging a pre-lithiation cell including a positive electrode. The positive electrode comprises a positive electrode active material comprising a lithium manganese-based oxide and a lithium metal counter electrode. The electrochemical charging over-lithiates the positive electrode to form an over-lithiated positive electrode. Then, separating the over-lithiated positive electrode from the pre-lithiation cell and fabricating a secondary battery including the over-lithiated positive electrode and a negative electrode including a negative electrode active material; subjecting the secondary battery to a first charging to form a first-charged secondary battery; resting the first-charged secondary battery; and subjecting the rested secondary battery to a second charging. The maximum voltage of the secondary battery in the first charging is lower than the maximum voltage of the secondary battery in the second charging.