Carbon Negative Electrode Material for Faster Li-Ion Intercalation
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Solution Overview
Problem
Current lithium-ion batteries face challenges in simultaneously improving energy density, cycle performance, and rate performance, with existing active materials failing to effectively manage lithium ion insertion and extraction rates, leading to cycle attenuation and reduced efficiency.
Innovation Solution
A negative active material with a carbon component, characterized by a specific graphitization degree and K value, crystal size ratios, and particle size distribution, optimized to enhance lithium ion insertion and extraction rates, thereby improving the battery's energy density, cycle performance, and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active materials are used in lithium-ion batteries, then the battery can operate with basic performance, but the energy density, cycle performance, and rate performance cannot be simultaneously improved
Solution Approach 1:
The patent applies parameter changes by precisely controlling the graphitization degree (Gr = 0.90-0.96) and K value (0.04-0.16) of the carbon material, along with specific crystal size ratios (Lc/S < 4.5, La/S > 20). These parameter optimizations enable the material to achieve both high cycle performance (80% capacity retention after 500 cycles at 45°C) and high rate performance (76.5 mAh/g at 10C rate), resolving the contradiction between reliability and productivity.
2Reliability
If the lithium ion insertion and extraction rates are not optimized, then the battery structure remains simple, but lithium plating occurs and cycle capacity retention decreases
Solution Approach 1:
The patent optimizes specific material parameters including graphitization degree (0.90-0.96), K value (0.04-0.16), and crystal size ratios (Lc/S < 4.5, La/S > 20), along with particle size distribution (Dv10=3-8 μm, Dv90=15-30 μm). These controlled parameter changes improve lithium ion insertion/extraction rates and suppress lithium plating, achieving 80% capacity retention after 500 cycles without increasing device complexity.
3Stability of the object's composition
If the carbon material has high graphitization degree, then the structural stability improves, but the lithium ion diffusion rate may decrease
Solution Approach 1:
The patent identifies an optimal parameter window where graphitization degree Gr = 0.90-0.96 and K value = 0.04-0.16. Within this range, the carbon material achieves both structural stability (evidenced by 80% capacity retention after 500 cycles) and adequate lithium ion diffusion rate (76.5 mAh/g at 10C rate). The specific crystal size ratios (Lc/S < 4.5, La/S > 20) further balance these competing requirements.
4Productivity
If the particle size is reduced to improve rate performance, then the lithium ion diffusion distance decreases, but the first-cycle coulombic efficiency may be affected
Solution Approach 1:
The patent optimizes particle size distribution with Dv10 = 3-8 μm and Dv90 = 15-30 μm, achieving a balance between rate performance (76.5 mAh/g at 10C) and first-cycle coulombic efficiency (93.5%). This controlled particle size range minimizes lithium ion diffusion distance while limiting excessive surface area that would increase SEI formation and efficiency loss.
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 optimized negative active material significantly increases the first-cycle coulombic efficiency, suppresses lithium plating, and enhances cycle capacity retention and expansion rates, leading to improved overall performance of lithium-ion batteries.
Implementation Method 1
a key technical issue to be solved urgently is that to increase an energy density, cycle performance, and rate performance of the battery. Improving an active material in an electrode plate is one of approaches to solving such issue
Data Source
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AI summary
A negative active material includes a carbon material. The carbon material satisfies the following relationship: 6 < GrIK < 16, Gr is a graphitization degree of the carbon material, measured by means of X-ray diffraction; and K is a ratio Id/Ig of a peak intensity Id of the carbon material at a wavenumber of 1250 cm-1 to 1650 cm-1 to a peak intensity Ig of the carbon material at a wavenumber of 1500 cm-1 to 1650 cm-1, and is measured by using Raman spectroscopy, and K is 0.06 to 0.15.The negative active material according to this application can significantly improve an energy density, cycle performance, and rate performance of the electrochemical device.