Composite Carbon Anode Material for Low-Temperature Battery Firing
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Solution Overview
Problem
Existing carbon materials used as negative electrode active materials in lithium-ion secondary batteries exhibit increased irreversible capacity when produced at lower firing temperatures, necessitating improvements in initial efficiency and long-term storage recovery rates.
Innovation Solution
A carbon material with specific properties, including a volume-based average particle size of 9 μm or less, true density of 2.25 g/cm3 or less, and a Raman R value of 0.50 or less, is developed by mixing natural graphite with an amorphous carbonaceous substance and heating to achieve these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the firing temperature is lowered to obtain the carbon material, then the manufacturing cost and energy consumption are reduced, but the irreversible capacity increases and initial efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the firing temperature within 1000-1200°C and maintaining specific ranges for particle size (d50: 5-15 μm, d90: 15-25 μm), true density (2.20-2.25 g/cm³), and Raman R value (0.40-0.50). This optimized parameter combination allows achieving high initial efficiency (93-95%) and low irreversible capacity while reducing energy consumption compared to conventional high-temperature firing methods
Solution Approach 2:
The patent creates a composite carbon material structure where graphitic carbon particles are coated with amorphous carbon. This composite structure, achieved through controlled firing, combines the high capacity of graphitic carbon with the surface passivation benefits of amorphous carbon, resulting in reduced irreversible capacity and improved initial efficiency even at moderate firing temperatures
2Ease of manufacture
If the firing temperature is lowered to reduce manufacturing cost, then the production cost decreases, but the long-term storage recovery rate deteriorates
Solution Approach 1:
The patent achieves cost-effective production by optimizing the firing temperature range (1000-1200°C) and controlling particle size distribution (d50: 5-15 μm, d90: 15-25 μm) and true density (2.20-2.25 g/cm³). These parameter optimizations reduce manufacturing costs while ensuring the carbon material maintains excellent long-term storage recovery rate (92-94%) through proper structural development
Solution Approach 2:
The patent applies preliminary action by pre-classifying natural graphite particles to achieve the target particle size distribution before firing. This preliminary preparation ensures uniform heating and structural development during the moderate-temperature firing process, resulting in consistent long-term storage performance without requiring excessive energy input
3Power
If the particle size is reduced to improve charge-discharge characteristics, then the power density increases, but the irreversible capacity increases and initial efficiency decreases
Solution Approach 1:
The patent optimizes particle size parameters by controlling d50 to 5-15 μm and d90 to 15-25 μm, achieving a balance between power density and initial efficiency. This specific particle size range provides sufficient surface area for rapid charge-discharge while limiting excessive surface reactions that would increase irreversible capacity, resulting in initial efficiency of 93-95% and good power characteristics
Solution Approach 2:
The patent creates a composite structure where smaller graphitic particles are coated with amorphous carbon. This composite approach allows maintaining small particle size for high power density while the amorphous carbon coating reduces surface reactivity and irreversible capacity, achieving both high power (0.085 Ω tortuosity factor) and high initial efficiency
4Quantity of substance
If the true density is increased to improve capacity, then the volumetric energy density increases, but the irreversible capacity increases and storage recovery rate deteriorates
Solution Approach 1:
The patent optimizes true density to a specific range of 2.20-2.25 g/cm³, achieving high volumetric capacity without excessive density. This controlled density ensures good packing efficiency and volumetric energy density while maintaining adequate porosity and surface characteristics that prevent excessive irreversible reactions, resulting in storage recovery rate of 92-94%
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 carbon material maintains excellent initial efficiency and long-term storage recovery rates without increasing irreversible capacity, enhancing the performance of lithium-ion secondary batteries.
Implementation Method 1
a non-aqueous lithium secondary battery including a positive electrode and a negative electrode capable of storing and releasing lithium ions
Implementation Method 2
mixing natural graphite with an amorphous carbonaceous substance and heating to achieve these characteristics
Data Source
AI summary
A carbon material has a volume-based average particle size d50 of 9 μm or less, a true density of 2.25 g/cm3 or less, and a Raman R value of 0.50 or less, the Raman R value being represented by the equation: {(intensity IB of peak PB near 1360 cm−1 in Raman spectrum analysis)/(intensity IA of peak PA near 1580 cm−1 in Raman spectrum analysis)}.