Crystalline Carbon Negative Electrode with Nanoparticle Pores
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Solution Overview
Problem
Lithium rechargeable batteries face challenges in maintaining cycle-life due to the instability and limited capacity of traditional carbon-based negative active materials, necessitating the development of more effective negative active materials that can buffer volume expansion and maintain electrical conductivity.
Innovation Solution
A negative active material comprising crystalline carbon with pores and amorphous conductive nanoparticles dispersed inside or on the surface, where the conductive nanoparticles have a full width at half maximum of 0.35 degrees or greater at the crystal plane, and are mixed with amorphous carbon to enhance mechanical strength and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-carbon-based negative active materials (such as Si) are used to achieve high capacity, then capacity is improved, but volume expansion occurs leading to poor cycle-life
Solution Approach 1:
The patent embeds conductive nanoparticles (such as Si, Sn, or their alloys) inside the porous structure of crystalline carbon particles. This nesting approach allows the high-capacity nanoparticles to be contained within a stable carbon matrix that accommodates their volume expansion, thereby maintaining both high capacity and good cycle-life.
Solution Approach 2:
The patent utilizes porous crystalline carbon materials with controlled pore sizes to house the conductive nanoparticles. The porous structure provides buffer space for volume expansion of the nanoparticles during lithium insertion/extraction cycles, preventing structural degradation and maintaining cycle stability while preserving high capacity.
2Reliability
If conductive particles are used to enhance electrical conductivity, then electrical conductivity is improved, but particle aggregation occurs reducing effectiveness
Solution Approach 1:
The patent creates local conductive regions by dispersing conductive nanoparticles specifically within the pores of crystalline carbon particles. This localized approach ensures electrical conductivity is enhanced at critical interfaces without requiring uniform distribution throughout the entire electrode, preventing aggregation while maintaining conductivity.
Solution Approach 2:
The crystalline carbon particles act as an intermediary matrix that disperses and stabilizes conductive nanoparticles. The carbon matrix prevents direct contact and aggregation between conductive particles while maintaining electrical pathways through the porous structure, thereby preserving both conductivity and dispersion stability.
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 proposed solution significantly improves the cycle-life and capacity retention of lithium rechargeable batteries by effectively buffering volume expansion and maintaining electrical conductivity, leading to enhanced battery performance.
Implementation Method 1
capable of buffering volume expansion upon insertion and extraction of lithium
Implementation Method 2
capable of intercalating and deintercalating lithium ions
Implementation Method 3
maintaining electrical conductivity
Data Source
AI summary
Embodiments of the present invention are directed to negative active materials for lithium rechargeable batteries and to lithium rechargeable batteries including the negative active materials. The negative active material includes a crystalline carbon material having pores, and amorphous conductive nanoparticles in the pores, on the surface of the crystalline carbon, or both in the pores and on the surface of the crystalline carbon. The conductive nanoparticles have a FWHM of about 0.35 degrees (°) or greater at the crystal plane that produces the highest peak as measured by X-ray diffraction.