Composite Positive Electrode Plate for High-Energy Li-Ion Cells
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Solution Overview
Problem
Existing lithium-ion batteries face challenges in achieving high mass energy density and volumetric energy density, while maintaining good electrochemical performance and safety performance, particularly due to performance degradations associated with the use of plastic current collectors with metal coating layers.
Innovation Solution
A positive electrode plate is designed with a composite current collector having a thin conductive layer and a polymer-based support layer, combined with an electrode active material layer that includes a specific distribution of binder and conductive agent, optimizing the thickness and compacted density to enhance energy density and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a plastic current collector with a metal coating layer is used, then the energy density is increased, but the electrochemical performance and processing performance deteriorate
Solution Approach 1:
The patent uses a composite current collector structure consisting of a polymer support layer and a metal conductive layer. The polymer support layer (e.g., polyolefin) provides mechanical strength and chemical stability, while the thin metal conductive layer (30-300 nm thick) provides electrical conductivity. This composite structure achieves high energy density by reducing overall current collector weight and thickness while maintaining good electrochemical performance through the synergistic combination of materials with complementary properties.
2Quantity of substance
If the conductive layer thickness is reduced to increase energy density, then the mass energy density improves, but the risk of internal short circuits and metal burrs increases
Solution Approach 1:
The patent optimizes the thickness parameter of the metal conductive layer to be within 30-300 nm, which is significantly thinner than conventional metal current collectors but thick enough to maintain adequate electrical conductivity and prevent internal short circuits. The polymer support layer thickness is optimized to 1-30 μm to provide sufficient mechanical support and electrical insulation. These parameter optimizations balance energy density improvement with safety performance, reducing metal burr formation while preventing internal short circuits.
3Quantity of substance
If a thinner current collector is used to minimize battery volume, then the volumetric energy density increases, but the mechanical strength and processing performance decrease
Solution Approach 1:
The polymer support layer provides excellent mechanical strength and flexibility, enabling the current collector to be made very thin (total thickness can be less than 10 μm) while maintaining adequate mechanical integrity for processing and assembly. The polymer material's inherent toughness and elasticity compensate for the reduced thickness, preventing brittle failure during handling and processing operations.
4Quantity of substance
If the electrode active material layer thickness is increased to improve capacity, then the energy density increases, but the sheet resistance increases and electrochemical performance deteriorates
Solution Approach 1:
The patent optimizes the electrode active material layer thickness to be not greater than 170 μm, balancing capacity and electrochemical performance. The sheet resistance is controlled within 0.1-10 ohms through optimization of the conductive agent content and distribution, active material particle size, and layer density. This parameter optimization ensures adequate electron and ion transport while maximizing energy storage capacity within the thickness constraint.
Data Source
AI summary
This application relates to the battery field, and specifically, to a positive electrode plate, an electrochemical apparatus, and an apparatus. The positive electrode plate in this application includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, where the current collector includes a support layer and a conductive layer disposed on at least one surface of the support layer, a single-sided thickness D2 of the conductive layer satisfies 30 nmD23 μm, a thickness D1 of the support layer satisfies 1 μmD130 μm, and the support layer is made of a polymer material or a polymer composite material; and the electrode active material layer includes an electrode active material, a binder, and a conductive agent, and a total thickness Dtotal of the electrode active material layer is not greater than 170 μm.