Silicon Nanowire Graphite Composite for Battery Stability
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Solution Overview
Problem
High-capacity silicon-based negative electrode materials for lithium batteries face rapid deterioration due to volumetric expansion during lithium intercalation and deintercalation, leading to poor charge and discharge characteristics and shortened lifespan.
Innovation Solution
A negative active material comprising silicon nanowires and nanoparticles combined with graphite, where the silicon nanowires and nanoparticles are disposed on graphite particles to form a composite, enhancing structural stability and preventing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pure silicon-based negative electrode materials are used to achieve high capacity, then theoretical capacity reaches 3,570 mAh/g, but volumetric expansion of about 280% causes particle pulverization and rapid deterioration of charge and discharge characteristics
Solution Approach 1:
The silicon-based negative electrode material is segmented into nanowires and nanoparticles, which are then composite with graphite particles. This segmentation prevents particle pulverization during volumetric expansion while maintaining high capacity, resolving the contradiction between high capacity and reliability
Solution Approach 2:
The patent creates a composite material structure where silicon nanowires and nanoparticles are combined with graphite particles. This composite structure provides both the high capacity of silicon and the structural stability of graphite, preventing deterioration of charge and discharge characteristics
2Quantity of substance
If silicon particles are used as negative electrode material, then high theoretical capacity is achieved, but lifespan characteristics rapidly deteriorate due to pulverization from volumetric expansion
Solution Approach 1:
Silicon is segmented into nanoscale wires and particles that are composite with graphite, preventing the pulverization that leads to lifespan deterioration while preserving high theoretical capacity
Solution Approach 2:
The composite structure of silicon nanowires/nanoparticles with graphite provides long-term structural stability, maintaining lifespan characteristics while achieving high theoretical capacity
3Quantity of substance
If high capacity silicon-based materials are used, then next generation battery performance is achieved, but initial charge and discharge efficiencies deteriorate due to structural instability
Solution Approach 1:
The composite of silicon nanowires/nanoparticles with graphite maintains structural integrity during initial charge and discharge cycles, preserving high specific capacity while improving initial charge and discharge efficiencies
Data Source
AI summary
A negative active material including graphite; silicon nanowires; and silicon nanoparticles, wherein a silicon nanowire of the silicon nanowires and a silicon nanoparticle of the silicon nanoparticles are each disposed on a particle of the graphite to form a composite with the graphite.