Electrode Sheet Coating That Creates Expansion Space in Battery Cells
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Solution Overview
Problem
Existing battery cells face challenges in maintaining cycle performance due to volume expansion during charging and discharging, leading to electrolyte loss and metal dendrite formation, which deteriorates their reliability.
Innovation Solution
Incorporating a decomposable material in the electrode sheet that decomposes during charging and discharging to create expansion spaces, enhancing electrolyte retention and reducing metal dendrite formation by providing a recessed area for the active material layer, thus improving cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode sheet structure is designed to accommodate volume expansion during charging and discharging, then the cycle performance is improved, but the electrode sheet complexity increases due to the additional coating layer with decomposable material
Solution Approach 1:
The coating layer with decomposable material is applied in advance to the current collector before the active material layer is formed. This preliminary action creates a pre-designed expansion space that activates during charging-discharging cycles, allowing the electrode sheet to accommodate volume changes without structural damage, thereby improving cycle performance while maintaining a relatively simple overall structure
Solution Approach 2:
The decomposable material is localized in specific coating areas rather than uniformly distributed throughout the entire electrode sheet. This local quality approach allows the expansion space to be created only where needed, minimizing the addition of complex materials and structures while effectively addressing the volume expansion issue in critical regions
2Reliability
If a coating layer with decomposable material is added to create expansion space, then electrolyte retention capacity is improved, but the manufacturing process complexity increases
Solution Approach 1:
The coating layer formation process is merged with the existing electrode sheet manufacturing process. The decomposable material is incorporated into the coating slurry that is already applied to the current collector, combining multiple functions (protection, expansion space creation, electrolyte retention) into a single manufacturing step, thereby reducing overall process complexity despite the added functionality
3Reliability
If the decomposable material decomposes during charging and discharging to form recessed areas, then the suck-back rate of electrolyte solution is improved, but the manufacturing precision requirement increases for controlling the coating layer thickness and composition
Solution Approach 1:
The coating layer is designed with specific parameter ranges for thickness (1-20 μm) and decomposable material content (5-50 wt%) that are optimized to achieve the desired expansion space volume and recessed area formation. These parameter specifications ensure that the decomposable material decomposes at the right rate and extent during charging-discharging cycles to improve electrolyte suck-back rate without requiring extreme manufacturing precision
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 decomposable material in the electrode sheet improves electrolyte wettability, retention capacity, and reduces the risk of metal dendrites, thereby enhancing the battery cell's cycle performance and capacity.
Implementation Method 1
The pore forming material can decompose and release a gas during the charging and discharging process of the battery cell, and the gas may cause a pore structure in the active material layer when flowing through the active material layer, thereby increasing the porosity of the active material layer
Implementation Method 2
The lithium supplementing material can decompose and release lithium ions during the charging and discharging process (for example, a first charging process) of the battery cell, thereby realizing the lithium supplementation of a battery system, increasing the content of the lithium ions in the battery system
Implementation Method 3
During the cyclic charging and discharging process of the battery cell, the decomposable material is decomposed, the decomposable material gradually decreases, the active material layer corresponding to the position is recessed in the direction toward the current collector, and the surface of the active material layer facing away from the current collector forms a slight recessed area, so that an expansion space is reserved
Data Source
AI summary
The present application relates to an electrode sheet, a battery cell, a battery, and an electric device. The electrode sheet includes a current collector, a coating, and an active material layer. The coating is provided on at least one surface of the current collector and includes at least one coating area. The coating area includes a decomposable material. The decomposable material is configured to decompose under at least one condition of charging and discharging of the battery cell. The decomposable material includes at least one of a lithium supplementing material and a pore forming material. The lithium supplementing material includes a lithium ion-containing compound. The active material layer is provided on at least one surface of the current collector and covers the coating.