Wound Electrode Assembly Layout to Reduce Lithium Precipitation
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Solution Overview
Problem
Lithium precipitation on negative electrode plates in electrochemical apparatuses leads to reduced service life due to dendrite formation and uneven pressure distribution during clamping.
Innovation Solution
The electrochemical apparatus features a stacked and wound electrode assembly with a negative electrode plate having a first and second negative electrode active material layer, and a positive electrode plate with a first and second positive electrode active material layer. The negative electrode current collector includes a blank foil region, a single-coated region, and a double-coated region, while the positive electrode current collector has a double-coated region. A first layer of insulating material is located on the first negative electrode winding layer, enhancing flatness and reducing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode assembly is wound and stacked with uniform coating, then the manufacturing process is simple, but lithium precipitation occurs on the negative electrode plate surface
Solution Approach 1:
The patent applies local quality by creating a non-uniform coating distribution on the negative electrode plate. Specifically, the negative electrode active material layer has different thicknesses at different radial positions from the winding center, with thicker coating at the outer region and thinner coating at the inner region. This localized variation in coating quality prevents lithium precipitation by ensuring adequate material coverage where it is most needed during winding, while avoiding excess material that could cause dendrite formation.
2Manufacturing precision
If formation clamps apply pressure to thicker parts of the electrode assembly, then those parts are properly compressed, but thinner parts receive insufficient pressure leading to lithium precipitation
Solution Approach 1:
The patent applies preliminary action by pre-configuring the negative electrode plate with a specific coating thickness distribution before the clamping formation process. The coating is designed to be thinner at the inner radius and thicker at the outer radius, so that when uniform pressure is applied during clamping, the resulting compression is more uniform across the electrode assembly. This preliminary structural arrangement ensures that thinner parts receive adequate pressure and prevents lithium precipitation without requiring complex variable pressure clamping systems.
Data Source
AI summary
An electrochemical apparatus, including an electrode assembly. The electrode assembly includes a negative electrode plate and a positive electrode plate. The negative electrode plate includes a first negative electrode active material layer, a negative electrode current collector, a second negative electrode active material layer, and a first layer. The positive electrode plate includes a first positive electrode active material layer, a positive electrode current collector, and a second positive electrode active material layer. The negative electrode plate includes a first negative electrode winding layer and a second negative electrode winding layer. A negative electrode single-coated region of the negative electrode current collector is located on at least the first negative electrode winding layer and the second negative electrode winding layer. A positive electrode double-coated region of the positive electrode current collector is located on a side of the second negative electrode winding layer away from a winding central axis.