Amorphous Carbon Negative Electrode for Low-Expansion Li-Ion Cells
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Solution Overview
Problem
Lithium-ion batteries using graphite as a negative electrode material face issues with lithium dendrite formation, leading to thermal runaway risks and continuous cell thickness expansion, limiting volumetric energy density and portability.
Innovation Solution
Employing a negative electrode plate with a first amorphous carbon material having an interlayer spacing greater than 0.34 nm and average pore diameter of 2-20 nm, which suppresses lithium dendrite formation and provides a buffer for thickness expansion, combined with other carbon materials to enhance energy density and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite is used as negative electrode active material, then cost is low and lithium intercalation potential is close to 0V, but lithium dendrites easily occur causing thermal runaway risk
Solution Approach 1:
The patent changes the interlayer spacing parameter of the carbon material from the standard 0.34 nm in graphite to greater than 0.34 nm. This parameter change modifies the lithium intercalation potential and structure to suppress dendrite formation while maintaining low cost amorphous carbon materials
Solution Approach 2:
The patent uses composite amorphous carbon materials combining different carbon components with specific interlayer spacing and pore structures. This composite approach achieves both safety (dendrite suppression) and cost-effectiveness by utilizing abundant amorphous carbon resources
2Quantity of substance
If graphite is used as negative electrode active material, then theoretical capacity is 372 mAh/g, but cell thickness increases continuously with cycling reducing volumetric energy density
Solution Approach 1:
The patent changes the structural parameters of carbon materials by controlling interlayer spacing (>0.34 nm) and pore diameter (2-20 nm). These parameter changes enable higher capacity amorphous carbon materials that exhibit minimal thickness expansion during cycling, thereby improving volumetric energy density
Solution Approach 2:
The patent introduces porous structures with controlled pore diameters (2-20 nm) in the amorphous carbon negative electrode material. The porous structure provides buffering space for volume changes during lithium intercalation/deintercalation, suppressing cell thickness expansion while maintaining high capacity
3Adaptability or versatility
If graphite is used as negative electrode active material, then it is widely used commercially, but lithium dendrites occur causing continuous thickness expansion
Solution Approach 1:
The patent changes the interlayer spacing parameter to greater than 0.34 nm in amorphous carbon materials, which fundamentally alters the lithium insertion mechanism to prevent dendrite formation. This parameter change maintains commercial viability while eliminating the thickness expansion problem
Solution Approach 2:
The patent designs amorphous carbon materials with predetermined pore structures (2-20 nm) and interlayer spacing (>0.34 nm) that provide cushioning space before dendrites can form. This beforehand cushioning prevents the harmful thickening effect during cycling while maintaining commercial applicability
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 significantly reduces thickness expansion, enhances energy density, and improves safety and cycle performance of lithium-ion batteries, making them suitable for next-generation wearable devices.
Implementation Method 1
very small thickness expansion of the negative electrode plate is caused by intercalation and deintercalation of lithium ions
Data Source
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AI summary
The present disclosure provides a negative electrode plate, a preparation method and application thereof. A negative electrode active material of the negative electrode plate includes a first amorphous carbon material. An interlayer spacing (d002) of the first amorphous carbon material is greater than 0.34 nm, and an average pore diameter of pores of the first amorphous carbon material ranges from 2 nm to 20 nm. The negative electrode plate can help improve energy density of a lithium-ion battery and suppress expansion of an electrochemical energy storage apparatus during cycling.