Plant-Derived Carbon Anode for High-Capacity Li-Ion Batteries
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Solution Overview
Problem
Lithium ion secondary batteries for on-board use require carbonaceous materials with favorable charge/discharge capacities and resistance to oxidative degradation, while also having low resistance to ensure optimal battery output characteristics.
Innovation Solution
A carbonaceous material with specific properties, including an average interplanar spacing of 0.36 to 0.42 nm, a specific surface area of 8 to 30 m2/g, low nitrogen and oxygen content, and an average particle diameter of 1 to 4 μm, is developed using plant-derived char, which is demineralized and calcined under an inert gas atmosphere to reduce metal impurities and enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plant-derived carbon raw material is used to obtain carbonaceous material with fine pores, then charge/discharge capacities are improved, but resistance to oxidative degradation deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the calcination temperature (800-1000°C) and duration to optimize the carbon structure. This thermal treatment modifies the physical and chemical properties of the plant-derived carbon, reducing oxygen-containing functional groups while preserving the porous structure, thereby simultaneously improving oxidative stability and maintaining charge/discharge capacities
Solution Approach 2:
The patent creates a composite carbonaceous material by combining plant-derived carbon with controlled pore structures and specific surface area characteristics (8-30 m²/g). This composite approach integrates the advantages of renewable plant materials with engineered structural properties to achieve both high capacity and oxidative resistance
2Productivity
If carbonaceous material with large surface area and fine pores is used, then charge/discharge capacities are improved, but resistance deteriorates
Solution Approach 1:
The patent applies local quality by creating heterogeneous pore structures with different sizes and distributions within the carbonaceous material. The material possesses both micro-pores for high capacity and controlled meso-pores for stability, with specific surface area optimized to 8-30 m²/g. This localized structural variation allows different regions to fulfill different functions, achieving both high productivity and resistance
3Quantity of substance
If non-graphitizable carbon is used to exceed theoretical capacity of graphite, then charge/discharge capacity is improved, but resistance to oxidative degradation deteriorates
Solution Approach 1:
The patent transforms the chemical composition parameters of non-graphitizable carbon through controlled calcination, reducing oxygen content and modifying functional groups. This parameter optimization allows the material to exceed graphite's theoretical capacity (372 mAh/g) while achieving sufficient oxidative resistance for practical applications
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 resulting non-aqueous electrolyte secondary battery exhibits favorable charge/discharge capacities, resistance to oxidative degradation, and low resistance, maintaining high charge/discharge efficiency and output characteristics.
Implementation Method 1
calcined under an inert gas atmosphere to reduce metal impurities
Implementation Method 2
calcined under an inert gas atmosphere to reduce metal impurities and enhance performance
Implementation Method 3
average interplanar spacing d002 of the (002) plane within a range of 0.36 to 0.42 nm calculated by using the Bragg equation according to a wide-angle X-ray diffraction method
Implementation Method 4
specific surface area within a range of 8 to 30 m2/g obtained by a nitrogen adsorption BET three-point method
Implementation Method 5
non-graphitizable carbon capable of doping (charging) and dedoping (discharging) of lithium
Data Source
AI summary
A carbonaceous material for a non-aqueous electrolyte secondary battery, having an average interplanar spacing d002 of the (002) plane within a range of 0.36 to 0.42 nm calculated by using the Bragg equation according to a wide-angle X-ray diffraction method, a specific surface area within a range of 8 to 30 m2/g obtained by a nitrogen adsorption BET three-point method, a nitrogen element content of 0.5 mass % or less, an oxygen element content of 0.3 mass % or less, and an average particle diameter of 1 to 2.8 μm according to a laser scattering method.