Composite Graphite Anode for High-Density Battery Electrodes
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving high-density electrodes with improved rolling properties and capacity characteristics due to the limitations of natural and artificial graphite materials, including low discharge voltage, reduced high-rate charge and discharge characteristics, and difficulties in preparing electrodes with targeted porosity.
Innovation Solution
A negative electrode active material comprising a mixture of spherical artificial graphite and natural flake graphite in a specific weight ratio, along with a carbon coating layer, is used to enhance rolling properties and density, thereby improving the charge and discharge characteristics of secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as the negative electrode active material, then capacity characteristics are improved, but rolling property deteriorates making it difficult to prepare high-density electrodes with targeted porosity
Solution Approach 1:
The patent combines natural graphite particles and artificial graphite particles in a composite active material. Natural graphite provides high capacity characteristics while artificial graphite contributes good rolling property. The synergistic combination allows the negative electrode to achieve both high capacity and excellent rolling performance, resolving the contradiction between capacity characteristics and ease of manufacture.
Solution Approach 2:
The patent creates a composite material system consisting of natural graphite and artificial graphite in specific weight ratios (natural graphite 30-70 wt%, artificial graphite 30-70 wt%). This composite approach leverages the complementary properties of both materials: natural graphite's high capacity and artificial graphite's good rolling behavior, thereby simultaneously improving capacity characteristics and manufacturing ease.
2Duration of action of stationary object
If artificial graphite is used to improve cycle life characteristics, then cycle life is improved, but capacity characteristics deteriorate requiring greater amounts to be loaded
Solution Approach 1:
The patent merges artificial graphite (providing excellent cycle life) with natural graphite (providing high capacity) in a composite structure. This combination allows the negative electrode to achieve both long cycle life and high capacity characteristics without requiring excessive loading amounts, thereby resolving the trade-off between durability and capacity.
Solution Approach 2:
By formulating a composite active material with artificial graphite (30-70 wt%) for cycle life enhancement and natural graphite (30-70 wt%) for capacity improvement, the patent creates a material system that simultaneously delivers both long-term stability and high capacity, eliminating the need to overload the electrode to compensate for lower capacity.
3Volume of stationary object
If natural graphite particles are compressed to high density, then electrode density is improved, but electrolyte solution impregnation is hindered reducing high-rate charge and discharge characteristics
Solution Approach 1:
The composite structure of natural graphite and artificial graphite creates a heterogeneous morphology where artificial graphite particles provide void spaces and pathways for electrolyte penetration. This allows the electrode to maintain high density from natural graphite compression while preserving adequate electrolyte access for high-rate performance, resolving the density-speed contradiction.
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 proposed solution allows for the preparation of high-density negative electrodes with improved rolling properties and capacity characteristics, leading to enhanced charge and discharge performance and extended cycle life in lithium secondary batteries.
Implementation Method 1
carbon-based compound capable of reversibly intercalating and deintercalating lithium ions
Implementation Method 2
a carbon coating layer
Data Source
AI summary
Provided are a negative electrode active material including spherical artificial graphite and natural flake graphite, wherein the spherical artificial graphite and the natural flake graphite are included in a weight ratio of 80:20 to 95:5, and a negative electrode for a lithium secondary battery including the same.