Graphene-Protected Anode Particles for Lithium Batteries
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Solution Overview
Problem
Lithium-ion batteries face challenges with high-capacity anode active materials due to mechanical degradation, such as pulverization of particles during charge and discharge cycles, leading to shortened cycle life, and existing protective coatings are brittle and non-conductive, failing to prevent electrolyte contact and reactions.
Innovation Solution
The development of graphene-embraced anode particulates with a porous core and thin encapsulating layer, where graphene sheets provide mechanical strength and conductivity, accommodating volume expansion without significant volume increase, and a sacrificial material is removed to create a porous structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity anode active materials (such as Si, Ge, Sn) are used to increase lithium storage capacity, then reversible capacity is improved, but severe pulverization occurs during charge-discharge cycles due to expansion and contraction, shortening cycle life
Solution Approach 1:
The patent embeds high-capacity anode active material particles (Si, Ge, Sn) inside porous graphite particles, creating a core-shell structure where the graphite shell accommodates the expansion and contraction of the inner high-capacity material during lithium insertion and extraction, preventing pulverization while maintaining high reversible capacity
Solution Approach 2:
The patent creates a composite structure combining graphite (which forms protective SEI layer and has good structural stability) with high-capacity materials (Si, Ge, Sn), where the graphite component provides mechanical support and protects the inner material from pulverization during cycling
2Reliability
If protective coatings are applied to prevent pulverization of anode particles, then cycle life is improved, but the coatings are brittle and non-conductive, failing to prevent electrolyte contact and reactions
Solution Approach 1:
The patent uses porous graphite particles as the protective shell, where the porous structure allows lithium ions to penetrate through to the inner high-capacity material particles while the graphite itself forms a protective SEI layer that prevents harmful electrolyte contact and reactions
Solution Approach 2:
The patent creates a structure where the outer graphite shell provides protective qualities (forming SEI layer, preventing electrolyte contact) while the inner core provides high-capacity lithium storage, with each zone having optimized properties for its specific function
3Ease of manufacture
If conventional coating methods are used to protect anode particles, then manufacturing simplicity is maintained, but the process is time-consuming and involves tedious chemical oxidation, rinsing, and high-temperature exfoliation procedures
Solution Approach 1:
The patent combines the protective coating function and high-capacity material integration into a single mixing process, where porous graphite particles and high-capacity material particles are simply mixed together to form composite anode particles, eliminating the need for separate coating, oxidation, and exfoliation steps
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
This approach significantly enhances cycle life and reversible capacity, reduces irreversible capacity, and maintains structural integrity, allowing for high-rate capacity and compatibility with common electrolytes, while being environmentally benign and cost-effective.
Implementation Method 1
graphene sheets provide mechanical strength and conductivity
Implementation Method 2
accommodating volume expansion without significant volume increase
Implementation Method 3
thin encapsulating layer comprises multiple graphene sheets... accommodating volume expansion
Implementation Method 4
graphene-embraced anode particulates... for lithium batteries... reversible capacity
Data Source
AI summary
Provided is an impact-transfer method of producing multiple porous anode particulates for a lithium battery, the method comprising: (a) mixing multiple particles of a graphitic material, multiple composite particles comprising primary anode active material particles dispersed in or bonded by a sacrificial material, optional milling balls to form a mixture in an impacting chamber of an energy impacting apparatus; (b) operating the energy impacting apparatus for peeling off graphene sheets from the particles of graphitic material and transferring the peeled graphene sheets to surfaces of composite particles to produce particulates of graphene-encapsulated composite particles; (c) recovering the particulates from the impacting chamber; and (d) partially or completely removing the sacrificial particles from the particulates of graphene-encapsulated composite particles to obtain the multiple porous anode particulates.