Outer Electrode Plate Coating for Lithium Plating Suppression
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Solution Overview
Problem
The issue of black flecks and lithium plating on outer electrode plates during the cycling process of lithium-ion batteries, leading to reduced cycle performance and safety, is exacerbated by the higher current density and faster consumption rate of electrolyte solution in single-side-coated electrode plates of multi-tab and laminated structures.
Innovation Solution
The implementation of double material layers on single-sided outer electrode plates, with conductivity adjusted to match or be lower than that of inner electrode plates, reduces current density and consumption rate, thereby minimizing the risks of black flecks and lithium plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If single-side-coated electrode plates are used to reduce process cost and increase energy density, then energy density is improved, but current density becomes significantly higher leading to black flecks and lithium plating
Solution Approach 1:
The patent applies local quality by making the outer electrode plates double-side-coated while keeping inner electrode plates single-side-coated. This creates a non-uniform structure where outer plates have lower current density (due to twice the active material surface area) and inner plates have higher current density, thereby localizing the quality distribution to solve the harmful effects at critical locations.
Solution Approach 2:
The patent changes the parameter of coating configuration from single-side to double-side for outer electrode plates. This parameter change increases the active material surface area by approximately twofold, which directly reduces the current density on outer plates and prevents black flecks and lithium plating while maintaining high energy density.
2Ease of manufacture
If single-side-coated electrode plates are used to reduce process cost, then manufacturing cost is reduced, but cycle performance deteriorates due to electrolyte solution consumption and lithium plating
Solution Approach 1:
The patent implements local quality by differentiating the coating configuration between outer and inner electrode plates. Outer plates are double-side-coated to enhance reliability and reduce electrolyte consumption, while inner plates remain single-side-coated to maintain cost-effectiveness. This localized differentiation resolves the contradiction between manufacturing cost and cycle performance.
Solution Approach 2:
The patent creates a composite electrode assembly structure combining double-side-coated outer plates and single-side-coated inner plates. This composite structure integrates the benefits of both configurations: the double-side-coated outer plates provide enhanced cycle performance and reduced electrolyte consumption, while the single-side-coated inner plates maintain cost efficiency.
3Quantity of substance
If outer electrode plates have higher current density, then energy density is improved, but electrolyte solution consumption rate increases leading to performance reduction
Solution Approach 1:
The patent changes the coating configuration parameter for outer electrode plates from single-side to double-side, which increases the active material surface area by approximately twofold. This parameter change directly reduces current density and consequently reduces electrolyte solution consumption rate, preventing performance degradation while maintaining high energy density.
Solution Approach 2:
The patent transitions from a single-sided coating approach to a double-sided coating approach for outer electrode plates, effectively utilizing both surfaces of the current collector. This dimensional change in coating application increases the effective surface area for electrochemical reactions, reducing current density and electrolyte consumption.
Data Source
Figure 1~2
AI summary
A secondary battery (001) includes an electrode assembly (01). The electrode assembly (01) includes first electrode plate (10), second electrode plates (20), and separators (30). The first electrode plates (10) include outer first electrode plates (101) and an inner first electrode plate. The outer first electrode plates (101) are located on the two outermost sides of the electrode assembly (01), respectively. The first electrode plate (10) include first current collector (11) and first active material layers (12). Each first current collector (11) includes a first surface and a second surface. The first surface is closer to a housing (02) than the second surface. The corresponding first active material layers (12) are disposed on a first surface and a second surface of the inner first electrode plate. At least one of the outer first electrode plates (101) is a single-sided first electrode plate. A first active material layer (12) disposed on the single-sided first electrode plate includes a first material layer (121) and a second material layer (122). A conductivity of the single-sided first electrode plate is A S/cm, and a conductivity of the inner first electrode plate (102) is B S/cm, where A ≤ B.