Composite Graphite Cladding for Fast-Charging Battery Anodes
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Solution Overview
Problem
Secondary batteries, particularly in electric vehicles, face challenges with long charging times due to poor fast charging performance and low-temperature power performance, limiting their widespread adoption.
Innovation Solution
A composite graphite material with a bulk particle and a cladding layer of amorphous carbon, where the bulk particle is formed by aggregating primary particles and the kinetic carbon material is strategically located to enhance ion and electron transport, is developed. This material has an air oxidation temperature between 630°C to 730°C, optimizing the number of end faces and defects for improved charging speed and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional graphite materials are used in secondary batteries, then high energy density can be achieved, but fast charging performance and low-temperature power performance remain poor
Solution Approach 1:
The patent applies local quality by creating a composite graphite material where the surface region (cladding layer) has different properties from the bulk. The cladding layer contains kinetic carbon material with specific crystal orientations and defects that enhance ion transport, while the bulk maintains high capacity graphite structure. This local differentiation allows simultaneous optimization of fast charging performance at the surface and energy density in the bulk.
Solution Approach 2:
The patent employs composite materials by combining conventional graphite with kinetic carbon material (such as turbostratic carbon or disordered graphite) in a specific structure. The composite consists of a bulk graphite particle with a cladding layer containing kinetic carbon material that has enhanced ion transport properties. This composite structure enables the battery to achieve both high energy density from the graphite bulk and improved fast charging performance from the kinetic carbon cladding layer.
2Productivity
If graphite material structure is optimized for fast charging, then charging speed improves, but energy density may be compromised
Solution Approach 1:
The patent applies segmentation by dividing the graphite material into two distinct functional regions: a bulk particle providing high capacity and energy density, and a cladding layer providing fast ion transport. This segmentation allows each region to be optimized for its specific function without compromising the other, resolving the trade-off between charging speed and energy density.
3Productivity
If the number of end faces and defects is increased to improve ion transport, then fast charging performance improves, but structural stability may be reduced
Solution Approach 1:
The patent applies local quality by concentrating the defects and end faces specifically in the cladding layer rather than throughout the entire particle. The bulk particle maintains its structurally stable crystalline graphite structure, while the cladding layer contains the necessary defects and kinetic carbon material to enhance ion transport. This localized approach allows improved ion transport without compromising overall structural stability.
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
The composite graphite material enables secondary batteries to maintain high energy density while significantly improving fast charging performance and low-temperature power performance, addressing the limitations of existing graphite materials.
Implementation Method 1
an air oxidation temperature T0 of the composite graphite material is from 630°C to 730°C
Implementation Method 2
the composite graphite material has favorable transport performance of active ions and electrons, the active ions and the electrons exchange fast on a surface of the composite graphite material, and the active ions have high solid phase transport capacity within the composite graphite material
Data Source
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AI summary
The present application discloses a composite graphite material, a method for preparing the same, a negative electrode sheet, a secondary battery, a battery module, a battery pack, and an electrical apparatus. The composite graphite material comprises a bulk particle and a cladding layer located on at least a partial surface of the bulk particle, the bulk particle is a secondary particle formed by aggregation of more than two primary particles, the bulk particle comprises artificial graphite, the cladding layer comprises amorphous carbon, and an air oxidation temperature T0 of the composite graphite material is from 630°C to 730°C. The composite graphite material in the present application can enable the secondary battery to not only have a high energy density, but also have significantly improved fast charging performance and low-temperature power performance.