Multi-Layer Negative Electrode for Fast Charging and High Energy Density
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Solution Overview
Problem
Secondary batteries face challenges in achieving both high energy density and maintaining good fast charging and cycling performance, as increased energy density often compromises kinetic performance and service life.
Innovation Solution
A secondary battery design featuring a multi-layer negative-electrode plate structure with a primer layer and two film layers, where the first negative-electrode film layer includes artificial graphite with a high proportion of secondary particles, and the second layer includes a high proportion of artificial graphite, optimizing the particle size distribution and conductive agent content to enhance charge transfer and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density of the secondary battery is increased, then the energy storage capacity is improved, but the fast charging performance and cycling performance deteriorate
Solution Approach 1:
The negative electrode is divided into multiple layers with different functions: the first layer (close to current collector) uses artificial graphite with secondary particles for fast charging, while the second layer uses natural graphite for high capacity. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between fast charging and energy density.
Solution Approach 2:
Different regions of the negative electrode are assigned different material compositions and particle size distributions. The first negative electrode layer has artificial graphite with Dv50 of 3-6 μm optimized for kinetic performance, while the second layer has natural graphite with Dv50 of 8-15 μm optimized for capacity. This local differentiation enables simultaneous achievement of fast charging and high energy density.
2Speed
If the proportion of artificial graphite with secondary particles in the first negative electrode layer is increased (A≥50%), then the fast charging performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent specifies precise particle size parameters (Dv50 of 3-6 μm for artificial graphite, Dv50 of 8-15 μm for natural graphite) and composition ratios (A≥50%, B≥50%) to optimize fast charging performance. By controlling these parameters within defined ranges, the patent achieves reliable fast charging while maintaining manufacturability through clear specification standards.
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 enables the secondary battery to achieve both good fast charging performance and extended cycle life while maintaining high energy density, by improving charge transfer and ion conductivity through the optimized structure and material composition.
Implementation Method 1
optimizing the particle size distribution and conductive agent content to enhance charge transfer and ion conductivity
Implementation Method 2
optimizing the particle size distribution and conductive agent content to enhance charge transfer and ion conductivity
Data Source
AI summary
A secondary battery, a preparation method thereof, and an apparatus including the secondary battery are described. Specifically, the secondary battery includes a negative-electrode plate, where the negative-electrode plate is of a multi-layer structure, and the multi-layer structure sequentially includes: a negative-electrode current collector, a primer layer, and a negative-electrode film layer; the negative-electrode film layer includes a first negative-electrode film layer and a second negative-electrode film layer, and the first negative-electrode film layer is located between the primer layer and the second negative-electrode film layer; and the first negative-electrode film layer includes a first negative-electrode active material, the first negative-electrode active material includes first artificial graphite, at least some particles in the first artificial graphite are secondary particles, and a quantity proportion A of the number of the secondary particles to a total number of particles of the first negative-electrode active material satisfies A≥50%.