Silicon Particle Composite Electrodes With Carbon Buffering for Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium-ion battery electrodes face challenges with silicon particles due to their expansion during lithium insertion, leading to mechanical failure and loss of electrical contact, which affects cycle life and energy density.
Innovation Solution
The development of composite materials using silicon particles with average sizes between 10 nm and 40 μm and nanometer-sized features, combined with a carbonized polymer that acts as both a conductive and electrochemically active matrix, eliminating the need for metal foil current collectors and providing mechanical support and expansion buffering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used in battery electrodes to increase energy density, then the energy density is improved, but the silicon particles expand during lithium insertion causing mechanical failure and loss of electrical contact
Solution Approach 1:
The patent embeds silicon particles inside hollow carbon spheres, creating a nested structure where the carbon sphere acts as a container for the silicon particle. This nested configuration allows the silicon to expand during lithiation while remaining confined within the carbon sphere, preventing mechanical failure and maintaining electrical contact throughout cycling.
Solution Approach 2:
The patent creates a composite material system combining silicon particles with carbon spheres and conductive carbon matrix. The carbon spheres provide structural support and expansion buffering, while the conductive carbon matrix ensures electrical connectivity. This composite approach allows the system to benefit from silicon's high capacity while mitigating its expansion-related failures.
2Strength
If conventional metal foil current collectors are used to provide mechanical support, then the structural integrity is maintained, but the device complexity and weight increase
Solution Approach 1:
The patent removes the conventional metal foil current collector from the electrode structure and replaces it with a self-supported network of conductive carbon spheres. This extraction eliminates the need for separate current collector components, reducing device complexity and weight while maintaining mechanical integrity through the interconnected carbon sphere network.
Solution Approach 2:
The conductive carbon spheres serve multiple functions simultaneously: they act as structural support replacing the current collector, provide expansion buffering for silicon particles, maintain electrical conductivity through their conductive nature, and facilitate lithium ion transport. This multi-functionality eliminates the need for separate dedicated components.
3Quantity of substance
If silicon particles expand during lithium insertion, then the capacity is increased, but electrical contact is lost affecting cycle life
Solution Approach 1:
The hollow carbon sphere structure provides a confined space within which silicon particles can expand during lithium insertion. The carbon sphere walls maintain structural integrity and ensure continuous electrical contact with the conductive carbon matrix, preventing the loss of electrical contact that would otherwise occur due to silicon expansion.
Solution Approach 2:
The hollow carbon sphere acts as a flexible shell that can accommodate the volume changes of the silicon particle during lithiation and delithiation cycles. This flexible containment structure maintains electrical connectivity while allowing the necessary expansion and contraction movements.
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 results in self-supported electrodes with high energy density, improved cycle life, and reduced irreversible capacity, enabling efficient lithium insertion and extraction while maintaining electrical contact.
Implementation Method 1
a carbonized polymer that acts as both a conductive and electrochemically active matrix
Implementation Method 2
providing mechanical support and expansion buffering
Implementation Method 3
enabling efficient lithium insertion and extraction
Data Source
AI summary
Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight of silicon particles. The silicon particles have an average particle size between about 0.1 μm and about 30 μm and a surface including nanometer-sized features. The composite material also includes greater than 0% and less than about 90% by weight of one or more types of carbon phases. At least one of the one or more types of carbon phases is a substantially continuous phase.