Lithium Metal Anode Oxide Film Removal via Initial Discharge
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Solution Overview
Problem
Lithium metal secondary batteries face challenges due to the formation of an oxide film on the lithium metal surface, which reduces ion conductivity, leads to uneven lithium precipitation, and results in poor cycle performance and safety issues.
Innovation Solution
A method involving a partial discharge during the activation process to remove the oxide film on the lithium metal surface, with a discharge current density of 0.01 to 3 mA/cm2, followed by initial charging at 0.01 to 2 mA/cm2, using lithium metal as the negative electrode and metal oxides like vanadium or manganese oxides as the positive electrode material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as negative electrode to achieve high energy density, then energy density is improved, but oxide film formation on surface reduces ion conductivity and cycle life
Solution Approach 1:
The patent applies preliminary action by performing an initial discharge before the first charge cycle. This preliminary discharge removes the oxide film formed on the lithium metal surface during manufacturing and storage, preventing it from interfering with subsequent charge-discharge cycles. The discharge process reduces the oxide layer thickness, improving ion conductivity and establishing uniform lithium distribution patterns that enhance cycle life while maintaining high energy density.
Solution Approach 2:
The patent utilizes parameter changes by controlling the discharge current density within a specific range (0.01 to 3 mA/cm²) during the initial discharge. This controlled parameter change ensures effective oxide film removal while preventing excessive lithium dissolution or dendrite formation. By optimizing the discharge current density parameter, the method achieves both oxide film removal and uniform lithium precipitation, resolving the contradiction between energy density and cycle life.
2Ease of manufacture
If oxide film is present on lithium metal surface, then manufacturing is simplified, but ion conductivity is reduced and lithium precipitation becomes uneven
Solution Approach 1:
The preliminary discharge acts as a preprocessing step that uniformizes the lithium metal surface before normal operation. By removing the oxide film and creating uniform lithium distribution patterns during this initial discharge, the method ensures consistent electrochemical performance in subsequent cycles while maintaining manufacturing simplicity.
Solution Approach 2:
The method skips the problematic oxide film layer by using an initial discharge to rapidly remove it. This rushing through the oxide film removal process in the initial discharge phase prevents the oxide film from causing uneven lithium precipitation during normal operation, thereby improving manufacturing precision without complicating the manufacturing process.
3Speed
If high current density is used for charging, then charging speed is improved, but lithium grows in dendrite form reducing cycle life
Solution Approach 1:
The preliminary discharge before first charge creates favorable conditions for subsequent high-rate charging by removing the oxide film and establishing uniform lithium distribution. This preliminary action prepares the electrode structure to accommodate faster charging rates without forming dendrites, thus enabling both high charging speed and long cycle life.
Solution Approach 2:
The patent optimizes the discharge current density parameter (0.01 to 3 mA/cm²) during the initial discharge to create uniform lithium precipitation patterns. This parameter optimization ensures that subsequent charging, even at high rates, proceeds uniformly without dendrite formation, resolving the contradiction between charging speed and cycle life.
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 enhances ion conductivity, reduces performance variations, and improves lithium precipitation uniformity, thereby extending battery cycle life and enhancing price competitiveness by widening the selection of positive electrode materials.
Implementation Method 1
removing the oxide film on the surface of lithium metal by performing a partial discharge before an initial charge in an activation process
Implementation Method 2
allowing lithium to be uniformly precipitated
Data Source
AI summary
A method of manufacturing a secondary battery using lithium metal as a negative electrode, and more particularly, a method of manufacturing a secondary battery capable of removing an oxide film formed on a lithium metal by performing some initial discharges during the initial period of the activation process to thereby improve the cycling performance of the battery by allowing lithium to be uniformly precipitated. The result minimizes the reduction of ion conductivity by removing the oxide film formed on the surface of the lithium metal through the initial partial discharge and improves the battery cycle performance since the precipitation reaction of lithium becomes uniform.