Concave Electrode Plate Structure for Lithium Plating Mitigation
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Solution Overview
Problem
Wound electrode assemblies in rechargeable battery cells face issues with lithium precipitation and poor electrolyte infiltration, leading to safety and cycling performance problems due to swelling force concentration and inadequate electrolyte reflow during charging and discharging.
Innovation Solution
The electrode plate design incorporates concave portions on the active substance layer, which serve as electrolyte storage and swelling buffer spaces, guiding electrolyte reflow and reducing energy loss, with specific volume and angle configurations to optimize electrolyte circulation and infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wound electrode assemblies are used to form battery cells, then productivity and manufacturing efficiency are improved, but lithium precipitation and poor electrolyte infiltration occur leading to safety and cycling performance problems
Solution Approach 1:
The patent applies local quality by creating non-uniform thickness distribution in the active substance layer through concave portions. The layer has thinner regions (concave portions) and thicker regions, allowing different local functions: thinner regions facilitate electrolyte infiltration and prevent lithium precipitation, while thicker regions maintain sufficient active material. This local variation resolves the contradiction between manufacturing efficiency and performance reliability.
Solution Approach 2:
The patent uses curvature by introducing concave portions with specific geometric shapes (rounded bottom surfaces, inclined side walls at 45°-135° angles) into the active substance layer. These curved features reduce stress concentration during electrode swelling, improve electrolyte distribution, and prevent lithium precipitation. The curved geometry transforms the uniform flat structure into a functional non-uniform structure that maintains reliability while preserving manufacturing efficiency.
2Quantity of substance
If the active substance layer is made thicker to increase energy density, then energy capacity is improved, but swelling force concentration increases causing lithium precipitation
Solution Approach 1:
The patent implements local quality by creating regions of different thickness within the active substance layer. The concave portions provide thinner regions that reduce swelling force concentration and prevent lithium precipitation, while other regions maintain sufficient thickness for energy storage. This local differentiation allows the layer to simultaneously achieve high energy density and low swelling force concentration.
Solution Approach 2:
The patent converts the harmful effect of swelling force concentration into a beneficial feature by designing concave portions that intentionally create controlled thin regions. These regions act as stress relief zones that accommodate swelling during charging/discharging cycles, transforming the potential harm of thickness variation into a protective mechanism against lithium precipitation while maintaining overall high energy density.
3Reliability
If concave portions are added to the active substance layer to improve electrolyte infiltration and prevent lithium precipitation, then cycling performance is improved, but manufacturing complexity and processing difficulty increase
Solution Approach 1:
The patent uses standardized curved geometries for concave portions with specific parameters (rounded bottom surfaces, side wall angles of 45°-135°) that can be systematically formed during the coating process. These standardized curved features improve electrolyte infiltration and cycling performance while maintaining relatively simple manufacturing through controlled deposition techniques, thus balancing performance improvement with manufacturing feasibility.
Solution Approach 2:
The patent optimizes specific parameters of the concave portions (depth, width, side wall angle between 45°-135°, rounded bottom radius) to achieve the best balance between cycling performance and manufacturing complexity. By controlling these parameters within specific ranges, the patent ensures that the concave portions provide sufficient electrolyte infiltration pathways and swelling buffer space without creating excessive structural complexity that would significantly increase processing difficulty.
4Reliability
If concave portions with large volume are created to provide sufficient swelling buffer space, then lithium precipitation is prevented, but energy loss increases due to reduced active substance volume
Solution Approach 1:
The patent optimizes the volume and dimensions of concave portions by controlling their depth, width, and side wall angles within specific ranges. This parameter optimization ensures that the concave portions provide sufficient swelling buffer space to prevent lithium precipitation while minimizing the volume occupied by non-active regions, thus reducing energy loss and maintaining high energy density.
Solution Approach 2:
The patent applies partial action by creating concave portions with moderate rather than excessive volume. The concave portions are designed to provide just sufficient swelling buffer space needed to prevent lithium precipitation during normal cycling, rather than creating overly large voids. This partial action approach balances the prevention of lithium precipitation with the preservation of active substance volume, minimizing energy loss while achieving the desired reliability improvement.
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 design enhances cycling performance by reducing energy loss and preventing lithium precipitation, while ensuring balanced electrolyte infiltration and reflow, thereby improving the overall performance of the battery cell.
Implementation Method 1
the concave portion can also serve as an electrolyte guide channel for guiding reflow of the electrolyte
Implementation Method 2
the concave portion reserves a swelling buffer space for swelling of the active substance layer
Data Source
AI summary
An electrode plate includes: a current collector having a plurality of first surfaces; and an active substance layer provided on at least one of the plurality of first surfaces and having a second surface on a side away from the current collector; where the second surface is provided with at least one concave portion that is recessed relative to the second surface, a volume sum of cavity(s) formed by the at least one concave portion is a first volume V1, a material volume of the active substance layer is a second volume V2, and the first volume V1 and the second volume V2 satisfy:V1: (V1+V2)=0.1% to 30%.