Dual-Layer Graphite Anode for Energy Density and Fast Charging
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Solution Overview
Problem
Secondary batteries face a challenge in achieving high energy density while maintaining good quick charging and cycle performance, as high energy density designs often compromise quick charging performance.
Innovation Solution
A secondary battery design featuring a negative electrode plate with a first film of graphite and a second film of artificial graphite, where the particle size uniformity of the first film is between 0.45 and 0.6, and the second film is between 0.3 and 0.4, optimizing ion transmission paths and contact surfaces to enhance charging and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high energy density design is implemented, then energy density is improved, but quick charging performance deteriorates
Solution Approach 1:
The negative electrode film is divided into two distinct layers: a first negative electrode film containing graphite particles with 0.45-0.6 particle size uniformity, and a second negative electrode film containing artificial graphite particles with 0.3-0.4 particle size uniformity. This segmentation allows each layer to serve different functions - the first layer provides high energy density while the second layer facilitates rapid ion transport, thereby resolving the contradiction between energy density and quick charging performance.
Solution Approach 2:
Different regions of the negative electrode are assigned different material properties through the two-layer structure. The first layer uses graphite with specific particle size uniformity (0.45-0.6) optimized for energy density, while the second layer uses artificial graphite with different particle size uniformity (0.3-0.4) optimized for ion conduction speed. This local differentiation of material properties enables simultaneous optimization of both energy density and quick charging performance.
2Quantity of substance
If particle size uniformity of first film is increased to 0.45-0.6, then energy density is improved, but ion conduction impedance increases
Solution Approach 1:
The second negative electrode film acts as an intermediary layer between the electrolyte and the first negative electrode film. The artificial graphite particles in the second film with 0.3-0.4 particle size uniformity provide low-impedance ion conduction pathways, mediating the ion transport between the electrolyte and the higher-impedance first film. This intermediary structure allows the first film to maintain high energy density while the overall impedance remains low due to the second film's superior ion conduction properties.
3Speed
If particle size uniformity of second film is decreased to 0.3-0.4, then quick charging performance is improved, but energy density decreases
Solution Approach 1:
The negative electrode is segmented into two functional layers where the second film with decreased particle size uniformity (0.3-0.4) is specifically dedicated to quick charging function, while the first film handles energy density. This segmentation allows the second film to optimize for speed without compromising the overall energy density, as the first film compensates for the lower packing efficiency of the second film.
Data Source
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AI summary
This application relates to a secondary battery, a process for preparing the same and an apparatus containing the secondary battery. In particular, the negative electrode plate comprises a negative current collector and a negative electrode film, wherein the negative electrode film comprises a first negative electrode film and a second negative electrode film, the first negative electrode film is disposed on at least one surface of the negative current collector and comprises a first negative electrode active material, the first negative electrode active material comprises graphite, and the particle size uniformity of the first negative electrode active material is from 0.4 to 0.6; the second negative electrode film is disposed on the first negative electrode film and comprises a second negative electrode active material, the second negative electrode active material comprises artificial graphite, and the particle size uniformity of the second negative electrode active material is from 0.25 to 0.45. Secondary battery has high energy density and good quick charging performance and cycle performance.