Graphite Negative Electrode Plate for Fast Charging and Cycle Life
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Solution Overview
Problem
Current lithium-ion secondary batteries with negative electrodes made of lithium titanate and amorphous carbon have low energy density and inadequate cycle life, limiting their fast charge performance and widespread adoption in new energy vehicles.
Innovation Solution
A negative electrode plate design optimizing the thickness of the active material layer, orientation index, and particle distribution, characterized by the kinetic parameter D, ensures both high energy density and fast charging capabilities without compromising cycle life, using graphite as the active material and controlling the coating weight to maintain conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If lithium titanate and amorphous carbon are used as negative electrode materials to achieve fast charging, then charging speed is improved, but energy density decreases
Solution Approach 1:
The patent changes the particle size parameter of graphite to D50≥3μm and controls the coating weight per unit area to 3-15μg/cm², optimizing the balance between fast charging capability and energy density. This parameter optimization allows the negative electrode to achieve both rapid lithium ion insertion/extraction and high capacity utilization.
Solution Approach 2:
The patent uses composite graphite particles formed by spheroidizing graphitizable filler and graphitizing them at high temperature. This composite structure combines the fast charging properties of graphite with optimized morphology, achieving both high energy density and fast charge performance when paired with lithium nickel cobalt manganese oxide positive electrode.
2Quantity of substance
If conventional negative electrode structures are used to maintain high energy density, then energy density is preserved, but cycle life deteriorates
Solution Approach 1:
The patent optimizes the coating weight per unit area to 3-15μg/cm² and controls the thickness ratio of negative to positive electrode active materials to 0.05-0.30, which prevents lithium precipitation during fast charging and extends cycle life while maintaining high energy density of 260-320Wh/kg.
Solution Approach 2:
The patent applies different particle size distributions and coating densities locally optimized for fast charging, creating a negative electrode structure that simultaneously achieves high energy density and long cycle life through controlled material distribution and morphology.
3Speed
If fast charging is implemented without optimization, then charging speed increases, but lithium precipitation occurs
Solution Approach 1:
The patent changes the particle size parameter to D50≥3μm and controls coating weight to 3-15μg/cm², which optimizes lithium ion diffusion pathways and prevents lithium precipitation during fast charging by ensuring uniform current distribution and adequate ion transport.
Solution Approach 2:
The patent performs preliminary spheroidization and graphitization of filler particles before electrode assembly, creating an optimized pore structure and conductive network in advance that prevents lithium precipitation during subsequent fast charging operations.
Data Source
AI summary
The disclosure relates to a negative electrode plate and a secondary battery comprising the same. Specifically, the disclosure provides a negative electrode plate comprising a negative electrode current collector and a negative electrode layer coated on at least one surface of the negative electrode current collector, the negative electrode layer comprising a negative electrode active material, wherein the negative electrode active material comprises graphite, and the negative electrode layer meets: 4×L×VOI-1/4×Dn10≤25, wherein L represents the thickness of single-side negative electrode layer on the negative electrode current collector in millimeter; Dn10 represents the particle diameter corresponding to 10% of the number distribution of particles of the negative electrode active material in micrometer; Voi represents the orientation index of the negative electrode layer. The negative electrode plate can allow that a secondary battery containing the same has the combination of high energy density, fast charge, and long cycle life.