Anode Active Material Core-Shell Structure for Lithium Battery
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Solution Overview
Problem
Lithium secondary batteries with artificial carbon anodes face limitations in power output and life-span due to non-uniform lithium ion insertion and isolation, particularly at high temperatures, and existing solutions do not adequately address these issues.
Innovation Solution
An anode active material comprising a core of artificial graphite with a shell of amorphous carbon, where the Raman R value (ID/IG) is within a specific range (0.5 to 0.65) and standard deviation is less than 0.22, ensuring uniform shell thickness and enhanced lithium ion insertion in all directions, thereby improving power output and life-span.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If artificial carbon anode is used, then charging/discharging efficiency is improved, but capacity is reduced
Solution Approach 1:
The patent merges artificial graphite and amorphous carbon into a composite anode structure, combining the high efficiency of artificial graphite with the high capacity of amorphous carbon to achieve both improved charging/discharging efficiency and maintained capacity
Solution Approach 2:
The patent uses composite materials by creating a mixed structure of crystalline artificial graphite and amorphous carbon in the anode, leveraging the complementary properties of both material types to resolve the efficiency-capacity trade-off
2Productivity
If artificial graphite is used, then charging/discharging efficiency is improved, but power output is insufficient
Solution Approach 1:
The patent combines artificial graphite and amorphous carbon in a composite structure that merges the high efficiency of graphite with the high power output capability of amorphous carbon
Solution Approach 2:
The composite anode material integrates crystalline and amorphous carbon phases, where the amorphous carbon component provides enhanced power output while the crystalline graphite maintains high charging/discharging efficiency
3Manufacturing precision
If shell thickness is increased to improve uniformity, then manufacturing complexity increases
Solution Approach 1:
The patent controls the Raman R value parameter within a specific range (0.45-0.70) to ensure uniform shell thickness without requiring complex manufacturing processes, using parameter specification as a quality control mechanism
Solution Approach 2:
The patent replaces direct physical measurement and control of shell thickness with Raman spectroscopy analysis of the R value, substituting a complex mechanical measurement system with a simpler optical characterization method
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 anode active material with a controlled Raman R value and standard deviation enhances charging/discharging power output, rapid charging capabilities, and maintains high temperature storage properties without degrading life-span, as demonstrated by improved capacity retention rates over cycles.
Implementation Method 1
an anode formed of a carbon-based material capable of absorbing and discharging lithium ions
Implementation Method 2
non-uniform lithium ion insertion and isolation
Data Source
AI summary
An anode for lithium secondary battery includes a current collector and an anode active material layer including an anode active material and being formed on the current collector. The anode active material includes a core containing an artificial graphite and a shell formed on a surface of the core, the shell containing an amorphous carbon. An average of a Raman R value of the anode active material layer is in a range from 0.5 to 0.65, and a standard deviation of the Raman R value is less than 0.22. The Raman R value is defined as a ratio (ID/IG) of a D band intensity (ID) relative to a G band intensity (IG), and the D band and the G band are obtained from a Raman spectrum of the anode active material layer.