Composite Electrode Plate for Low-Resistance Li-Ion Current Collection
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high mass and volume energy density while maintaining good electrochemical performance due to the use of composite current collectors with poor conductivity and susceptibility to damage, leading to increased internal resistance and potential lithium precipitation during long-term cycling.
Innovation Solution
The electrode plate design includes a composite current collector with a conductive layer thickness of 30 nm to 3 μm, uneven distribution of conductive agents within the electrode active material layer, and a support layer with specific mechanical properties to enhance binding forces and conductivity, forming a robust conductive network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a metal-plated plastic current collector is used to reduce weight and increase energy density, then mass energy density is improved, but electrical conductivity and processing performance deteriorate
Solution Approach 1:
The current collector uses a composite structure consisting of a plastic support layer and a metal conductive layer. The support layer provides mechanical strength and weight reduction, while the metal layer restores electrical conductivity. This composite approach allows the current collector to simultaneously achieve low weight and high conductivity, resolving the contradiction between energy density improvement and electrical performance maintenance.
2Weight of moving object
If the conductive layer thickness is reduced to decrease current collector weight, then mass energy density is improved, but conductivity and mechanical strength deteriorate
Solution Approach 1:
The composite structure combines a thin metal conductive layer with a plastic support layer. The support layer compensates for the reduced mechanical strength of the thin metal layer, allowing the conductive layer to be made thinner without sacrificing overall structural integrity. This enables weight reduction while maintaining sufficient strength for battery assembly and cycling.
3Weight of moving object
If a thin conductive layer is used to reduce weight, then mass energy density is improved, but the conductive layer becomes susceptible to damage and internal resistance increases
Solution Approach 1:
The plastic support layer acts as a protective cushion for the thin metal conductive layer from the beginning. It prevents mechanical damage during battery assembly, electrode plate handling, and cycling processes. This beforehand protection ensures the thin conductive layer maintains its integrity and low resistance characteristics throughout the battery's service life, resolving the reliability issue.
4Ease of manufacture
If uniform conductive agent distribution is used in the electrode active material layer, then manufacturing simplicity is maintained, but electrical performance and binding force are insufficient
Solution Approach 1:
The conductive agent is distributed non-uniformly in the electrode active material layer, with higher concentration near the current collector interface and lower concentration toward the outer surface. This local quality variation optimizes electrical contact at the critical interface region where current collection occurs, while reducing conductive agent content elsewhere to lower resistance and improve overall electrical performance.
5Volume of stationary object
If high compaction density electrode plate is used to increase volume energy density, then volume energy density is improved, but processing performance and binding force may deteriorate
Solution Approach 1:
The binder composition is specifically optimized for high compaction density applications. By adjusting binder type, content, and molecular weight, the electrode plate maintains strong binding force even at high compaction densities. This parameter optimization allows achieving high volume energy density while preserving adequate processing performance during electrode plate fabrication and battery assembly.
Data Source
AI summary
The electrode plate according to the present application includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein the current collector includes a support layer and a conductive layer, the conductive layer has a single-sided thickness D2 satisfying: 30 nm≤D2≤3 μm; and the conductive agent is unevenly distributed in the electrode active material layer in a thickness direction of the electrode active material layer, in which the weight percentage of the conductive agent in the inner region of the electrode active material layer is higher than the weight percentage content of the conductive agent in the outer region of the electrode active material layer, and the binder in the inner region of the electrode active material layer includes a water-dispersible binder.