Mechanofused Silicon-Carbon Anode Composite for Swelling Control
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Solution Overview
Problem
Silicon-based anode active materials for lithium secondary batteries experience significant volume changes during lithium intercalation and deintercalation, leading to pulverization and contact loss with current collectors, limiting their performance due to inadequate surface coating caused by differences in surface energy with graphite.
Innovation Solution
A silicon/carbon anode composite is created by surface-coating silicon microparticles with a polymer or pitch and binding them to a carbonaceous material through a mechanofusion process, eliminating the need for additional heat treatment and preventing volumetric swelling, while enhancing capacity and life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode active material to achieve high lithium binding capacity, then theoretical capacity is improved, but volume change during lithium intercalation and deintercalation causes pulverization and contact loss
Solution Approach 1:
Silicon nanoparticles are embedded within hollow carbon spheres, creating a nested structure where the inner silicon particles are protected by the outer carbon shell. This nesting approach allows the silicon to expand and contract during lithium intercalation/deintercalation while maintaining structural integrity and preventing pulverization.
Solution Approach 2:
A carbon coating layer is formed on the surface of silicon nanoparticles, creating a flexible shell that can accommodate volume changes during charge/discharge cycles. This carbon shell prevents direct contact between silicon and electrolyte, reducing pulverization while maintaining lithium ion transport pathways.
2Reliability
If surface coating is performed to prevent silicon pulverization, then structural stability is improved, but coating is insufficient due to difference in surface energy between silicon and graphite
Solution Approach 1:
A carbonaceous material serves as an intermediary layer between silicon nanoparticles and the external environment. This carbonaceous coating material has compatible surface energy with both silicon and graphite, enabling effective adhesion and uniform coating without requiring complex surface treatment processes.
Solution Approach 2:
A composite structure is created combining silicon nanoparticles with carbonaceous material. This composite approach leverages the high capacity of silicon while utilizing the structural stability and surface compatibility of carbonaceous materials to achieve uniform coating and prevent pulverization.
3Reliability
If graphite is used as anode active material to ensure structural stability, then reliability is improved, but electric charge capacity is limited
Solution Approach 1:
The invention merges the advantages of both silicon and graphite by creating a composite anode structure. Silicon nanoparticles provide high lithium binding capacity while the carbonaceous material and hollow sphere structure provide structural stability, achieving a synergistic effect that combines the benefits of both materials.
Solution Approach 2:
A composite anode material is developed combining silicon and carbonaceous materials in a specific architecture. This composite structure enables the anode to achieve both the high capacity of silicon and the structural stability of graphite, overcoming the limitations of using either material alone.
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 silicon/carbon anode composite achieves improved capacity and life characteristics by preventing volumetric swelling and maintaining structural integrity, with enhanced ion conductivity and electrochemical stability, even after multiple charge/discharge cycles.
Implementation Method 1
silicon microparticles to a polymer solution or pitch solution and carrying out pulverization to prepare a mixture; subjecting the pulverized mixture to centrifugal separation, followed by drying, to prepare silicon nanoparticles surface-coated with a polymer or pitch
Implementation Method 2
coating the surface of silicon microparticles with a polymer or pitch and allowing the resultant product to be physicochemically bound to the surface of the carbonaceous material through a mechanofusion process
Implementation Method 3
subjecting the pulverized mixture to centrifugal separation, followed by drying, to prepare silicon nanoparticles surface-coated with a polymer or pitch
Data Source
AI summary
The present disclosure relates to a silicon/carbon anode composite for a lithium secondary battery, a method for preparing the same and a lithium secondary battery including the same. Particularly, the silicon/carbon anode composite for a lithium secondary battery is obtained by coating the surface of silicon microparticles with a polymer or pitch and allowing the resultant product to be physicochemically bound to the surface of the carbonaceous material through a mechanofusion process, and thus needs no additional heat treatment and can be processed with ease, is prevented from volumetric swelling of silicon caused by lithium-ion intercalation and deintercalation, and can provide a battery with significantly improved capacity and life characteristics.