Multilayer Carbon-Coated Silicon Anodes for Conductivity and Expansion
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Solution Overview
Problem
Silicon-based anode materials for lithium-ion batteries face issues of low intrinsic conductivity, large volume expansion, and irreversible capacity loss due to cracking, which hinder their commercialization and scalability.
Innovation Solution
A multilayer composite carbon coating is deposited on silicon-based anode materials using unbalanced magnetron sputtering with alternating negative and positive biases to enhance conductivity and stability, comprising a diamond-like carbon transition layer and a graphite-like functional layer, avoiding high-temperature processes and impurity introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode materials are used to replace graphite, then the capacity is improved, but the volume expansion and structural stability deteriorate
Solution Approach 1:
The patent applies nested structure by placing silicon particles inside a porous carbon matrix, forming a core-shell configuration where the silicon anode material is nested within the protective carbon framework. This nested structure allows the silicon to expand and contract during lithium insertion/extraction while the outer carbon layer maintains overall structural integrity and prevents particle aggregation, thus resolving the contradiction between high capacity and structural stability.
Solution Approach 2:
The patent employs a flexible porous carbon matrix that can accommodate the volume expansion of silicon during lithiation. The carbon shell acts as a flexible container that expands and contracts with the silicon core, preventing structural collapse and maintaining electrode integrity throughout charge-discharge cycles, thereby addressing the volume expansion issue while preserving high capacity.
2Quantity of substance
If silicon-based anode materials are used, then the capacity is improved, but the conductivity deteriorates
Solution Approach 1:
The patent creates a composite material system combining silicon particles with a conductive carbon matrix. The carbon component provides electrical conductivity pathways throughout the electrode structure, while the silicon particles contribute high capacity. This composite approach allows the material to simultaneously achieve both high capacity and good conductivity, resolving the contradiction between these two properties.
3Manufacturing precision
If high-temperature process is used for carbon coating, then the coating quality is improved, but the energy consumption and material agglomeration increase
Solution Approach 1:
The patent changes the deposition parameters from high-temperature thermal processes to low-temperature physical vapor deposition conditions. By using magnetron sputtering at relatively low temperatures with controlled bias voltages alternating between positive and negative values, the method achieves high-quality carbon coating without the energy consumption and agglomeration problems associated with high-temperature processing.
Solution Approach 2:
The patent employs periodic alternation of positive and negative bias voltages during the carbon deposition process. This periodic action controls the ion bombardment and film growth dynamics, enabling high-quality coating formation at low temperatures while preventing material agglomeration and reducing energy consumption compared to continuous high-temperature processing.
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 method achieves high conductivity and cyclic stability, with a specific capacity of 1008.6 mA h g−1 after 100 cycles, reducing volume expansion and improving structural integrity, thus enabling broader market application and efficient production.
Implementation Method 1
utilizing unbalanced magnetron sputtering, thereby obtaining the silicon-based anode material with high stability and conductivity for lithium-ion batteries
Implementation Method 2
by adjusting an alternate operation of a negative bias and a positive bias and utilizing unbalanced magnetron sputtering
Data Source
AI summary
Provided is a silicon-based anode material with high stability and conductivity for lithium-ion batteries, which is prepared by depositing a multilayer composite carbon coating on a surface of a silicon-based anode material for lithium-ion batteries by adjusting an alternate operation of a negative bias and a positive bias and utilizing unbalanced magnetron sputtering. Where a structure of the multilayer composite carbon coating, from a nano silicon power outward, comprises a diamond-like carbon transition layer and a high-conductivity graphite-like functional layer arranged alternately in sequence; an Sp3 structure of the diamond-like carbon transition layer has a carbon content of at least 65 at %; and an Sp2 structure of the graphite-like functional layer has a carbon content of at least 65 at %.