Porous Current Collector Electrode Coating via Shielding Film
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Solution Overview
Problem
The challenge is to form a uniform electrode mixture layer in lithium secondary batteries using current collectors with high porosity or hole openings, which is essential for high energy density and rapid charging characteristics, while preventing slurry leakage and non-uniformity during the electrode preparation process.
Innovation Solution
A method involving a shielding film that is brought into close contact with one surface of the current collector before coating the electrode slurry, allowing primary drying at a low temperature to form an interim electrode, and subsequent secondary drying after removing the film, ensuring uniform coating and controlled loading of the electrode mixture layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current collector with high porosity or hole openings is used, then lithium ion mobility and energy density are improved, but slurry leakage occurs and electrode mixture layer uniformity deteriorates
Solution Approach 1:
The patent applies a shielding film to the current collector surface before coating the electrode slurry. This preliminary action prevents slurry leakage through the pores during the coating process, while still allowing lithium ions to pass through during battery operation. The shielding film is removed after coating, leaving a uniform electrode mixture layer on the porous current collector.
Solution Approach 2:
The shielding film acts as an intermediary substance that temporarily blocks the pores of the current collector during the slurry coating process. This mediator prevents direct contact between the slurry and the porous structure, avoiding leakage and ensuring uniform coating, while not interfering with the final battery performance.
2Quantity of substance
If the electrode mixture layer thickness is increased to achieve high capacity, then battery capacity is improved, but energy density decreases and electrochemical reaction uniformity deteriorates
Solution Approach 1:
The patent uses a porous current collector with localized high-surface-area structures that provide adequate active material loading capacity while maintaining thin overall electrode thickness. The porous structure distributes the electrochemical reactions across a larger surface area, preventing concentration gradients and ensuring uniform reaction characteristics throughout the electrode.
Solution Approach 2:
The current collector employs a porous structure that increases the effective surface area for electrode material deposition. This allows achieving high battery capacity through increased surface area rather than increased thickness, thereby maintaining good electrochemical reaction uniformity and high energy density.
3Quantity of substance
If a thick electrode mixture layer is applied to simulate high capacity, then battery capacity is improved, but rapid charging characteristics deteriorate due to lithium ion concentration gradient
Solution Approach 1:
The porous current collector enables the electrode to achieve high capacity through increased surface area rather than increased thickness. The porous structure facilitates rapid lithium ion transport throughout the electrode, eliminating concentration gradients that would otherwise occur in thick electrodes, thereby maintaining excellent rapid charging characteristics.
Solution Approach 2:
The patent transitions from increasing capacity through thickness (one dimension) to increasing capacity through surface area (two-dimensional expansion via porous structure). This dimensional change allows high capacity while maintaining thin electrode geometry that supports rapid lithium ion diffusion and good charging characteristics.
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 method enables the use of current collectors with high porosity or hole openings, preventing slurry leakage and achieving a uniform electrode mixture layer, thereby improving the performance and stability of lithium secondary batteries by enhancing electrochemical reaction uniformity and lithium ion mobility.
Implementation Method 1
a shielding film is brought into close contact with one surface of a current collector on which the electrode slurry is not yet coated
Implementation Method 2
the electrode slurry is primarily dried at a relatively low temperature to form an interim electrode, and secondarily dried at a relatively high temperature after removing the shielding film
Implementation Method 3
a current collector in which through-pores or holes are formed to preserve movement of lithium ions
Data Source
AI summary
A method of preparing an electrode for a secondary battery, including:(i) a process of preparing a current collector in which through-pores or holes are formed and an electrode slurry containing an electrode active material;(ii) a process of bringing a shielding film into close contact with one surface of the current collector to shield pores or holes on the one surface of the current collector;(iii) a process of coating the electrode slurry on the other surface of the current collector to which the shielding film is not attached, and primarily drying to prepare an interim electrode;(iv) a process of removing the shielding film from the interim electrode; and(v) a process of secondarily drying the interim electrode to prepare the electrode.