Lithium-Ion Capacitor Doping for Uniform SEI Film Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deactivation rate of lithium increases in lithium-ion capacitors during durability tests due to uneven film thickness of the solid electrolyte interphase (SEI) film on the negative electrode surface, affecting the capacitor's durability.
Innovation Solution
A manufacturing method involving two-stage doping with specific current values (0.05 C to 0.2 C for initial uniform film formation and 0.25 C to 1 C for efficient completion, combined with tension application to maintain uniform pressure between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If doping is performed at high current value from the start, then productivity is improved, but the film thickness uniformity deteriorates
Solution Approach 1:
The doping process is divided into two distinct stages: a first doping stage at a first current value (0.05C to 0.2C) to form a uniform SEI film, and a second doping stage at a second current value (0.25C to 1C) to efficiently complete the doping. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between speed and uniformity.
Solution Approach 2:
The first doping stage performs a preliminary action by forming a uniform SEI film on the negative electrode surface before the main doping process. This preliminary uniform film formation prevents uneven lithium deposition that would occur with high current from the start, enabling subsequent high-current doping without sacrificing uniformity.
2Manufacturing precision
If doping is performed at low current value, then film uniformity is improved, but productivity deteriorates
Solution Approach 1:
The doping process is divided into two distinct stages: a first doping stage at a first current value (0.05C to 0.2C) to form a uniform SEI film, and a second doping stage at a second current value (0.25C to 1C) to efficiently complete the doping. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between speed and uniformity.
Solution Approach 2:
The two-stage doping process maintains continuous useful action by seamlessly transitioning from the first doping stage to the second doping stage. The uniform SEI film formed in the first stage enables the second stage to proceed at higher current without compromising uniformity, thus maintaining continuous productivity improvement while preserving film quality.
3Reliability
If uniform SEI film is formed on negative electrode, then lithium deactivation rate is reduced, but doping time increases
Solution Approach 1:
The doping process is divided into two distinct stages: a first doping stage at a first current value (0.05C to 0.2C) to form a uniform SEI film, and a second doping stage at a second current value (0.25C to 1C) to efficiently complete the doping. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between speed and uniformity.
Solution Approach 2:
The first doping stage performs a preliminary action by forming a uniform SEI film on the negative electrode surface before the main doping process. This preliminary uniform film formation prevents uneven lithium deposition that would occur with high current from the start, enabling subsequent high-current doping without sacrificing uniformity.
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
The method enhances the uniformity of the SEI film on the negative electrode, reducing lithium deactivation and improving the capacitor's durability.
Implementation Method 1
it has been found that, in a case where a lithium-ion capacitor is subjected to doping, the film thickness of a film (solid electrolyte interphase (SEI) film) formed on a surface of a negative electrode is uneven
Data Source
AI summary
The manufacturing method of the lithium-ion capacitor includes a step of performing doping at a first doping current value and a step of performing doping at a second doping current value. In the step of performing doping at the first doping current value, doping is performed at the first doping current value of 0.05 C or more and 0.2 C or less from the start of the doping. In the step of performing doping at the second doping current value, doping is performed at a second doping current value having a C rate higher than the first current value.