Anode Active Material Hard Carbon Coating Volume Expansion
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Solution Overview
Problem
The challenge is to develop an anode active material for lithium secondary batteries that improves high discharge capacity, efficiency, and output using earth graphite, a cheaper and low-grade raw material, while addressing expansion characteristics and structural stability issues.
Innovation Solution
A composite anode active material is created by mixing earth graphite with pitch coke and applying a hard carbon coating, with a specific mixing ratio and coating thickness, to enhance structural stability and control volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If earth graphite is used as anode active material, then cost is reduced, but structural stability and expansion characteristics deteriorate
Solution Approach 1:
The patent applies composite materials by combining earth graphite with artificial graphite in a specific ratio (70-95 wt% earth graphite and 5-30 wt% artificial graphite). This composite structure allows the use of cheaper earth graphite while the artificial graphite component provides structural stability and reduces expansion, thus resolving the contradiction between cost reduction and structural stability maintenance.
2Ease of manufacture
If earth graphite is used as anode active material, then cost is reduced, but capacity retention and output characteristics deteriorate
Solution Approach 1:
The composite structure combining earth graphite and artificial graphite improves capacity retention and output characteristics. The artificial graphite component provides better electrochemical stability and structural integrity during charge-discharge cycles, enabling the earth graphite-based anode to achieve satisfactory capacity retention (above 80% after 500 cycles at 45°C) and output performance.
3Ease of manufacture
If total internal pore volume is high after rolling, then manufacturing is easier, but high-temperature performance deteriorates
Solution Approach 1:
The patent controls the total internal pore volume of the anode to be within a specific range (0.3-0.6 mL/g) after rolling through parameter optimization. This parameter control ensures that the anode maintains sufficient porosity for lithium ion transport while limiting excessive pore formation that would occur during rolling, thereby preserving high-temperature storage characteristics and cycle life at elevated temperatures.
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 solution achieves improved electrochemical performance, including high capacity retention and output, while reducing costs by utilizing low-grade earth graphite, and effectively managing expansion characteristics.
Implementation Method 1
a core part in which earth graphite and pitch coke are mixed with each other; and a hard carbon coating for coating the core part
Implementation Method 2
a small change in crystal structure during intercalation and deintercalation processes of lithium ions enables continuous and repeated redox reactions to proceed in an electrode
Implementation Method 3
continuous and repeated redox reactions to proceed in an electrode
Data Source
AI summary
The present disclosure relates to a method of manufacturing an anode active material for a lithium secondary battery, the method including: mixing earth graphite and pitch coke with each other; preparing a raw material by adding and mixing a binder to the mixture; performing heat treatment on the raw material; graphitizing the heat-treated mixture to obtain a core part; immersing the core part in a hard carbon coating solution; and drying the coating solution in which the core part is immersed to obtain an anode active material.