Battery Electrolyte Composition for Self-Supporting Silicon Electrodes
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Solution Overview
Problem
Conventional lithium-ion battery electrodes require a metal foil current collector for mechanical support, which limits their capacity and cycle life due to silicon's high expansion and poor electrical conductivity, and existing silicon particles with small sizes suffer from low volumetric energy density and poor cycle life.
Innovation Solution
A self-supported composite electrode material is developed using a carbonized polymer as a continuous phase to hold silicon particles, eliminating the need for a metal foil collector and incorporating micron-sized silicon particles with nanometer-sized features to enhance electrical conductivity and accommodate volume changes during lithium insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal foil current collectors are used for mechanical support, then structural integrity is maintained, but capacity and cycle life are limited due to silicon expansion
Solution Approach 1:
The patent removes the metal foil current collector from the electrode structure and replaces it with a self-supported carbonized polymer matrix. This extraction eliminates the harmful mechanical constraints that limit silicon expansion while maintaining structural integrity through the flexible carbonized polymer network.
Solution Approach 2:
The patent creates a composite material system where silicon particles are embedded in a carbonized polymer matrix. This composite structure allows the silicon to expand and contract during cycling while the carbonized polymer provides mechanical support and maintains electrical conductivity without the constraints of metal foil.
2Reliability
If small-sized silicon particles are used, then electrical conductivity is improved, but volumetric energy density decreases
Solution Approach 1:
The patent applies local quality by using nanometer-sized features on the surface of micron-sized silicon particles. This creates different functional zones: the nanometer surface features provide high electrical conductivity and reaction activity, while the micron-sized core maintains high volumetric energy density. The carbonized polymer matrix further enhances local conductivity throughout the composite structure.
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 composite electrode achieves high energy density, improved cycle life, and reduced irreversible capacity by maintaining electrical contact and structural integrity despite silicon expansion, while eliminating the need for a metal foil collector.
Implementation Method 1
a self-supported composite electrode material is developed using a carbonized polymer as a continuous phase to hold silicon particles
Implementation Method 2
incorporating micron-sized silicon particles with nanometer-sized features to enhance electrical conductivity
Implementation Method 3
accommodate volume changes during lithium insertion
Data Source
AI summary
An energy storage device comprising a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode comprises a self-supporting composite material film, a separator between the first electrode and the second electrode, and an electrolyte in contact with the first electrode, the second electrode, and the separator, wherein the electrolyte comprises at least one of a fluorine-containing cyclic carbonate, a fluorine-containing linear carbonate, and a fluoroether. The composite material film having greater than 0% and less than about 90% by weight of silicon particles, and 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 can be a substantially continuous phase that holds the composite material film together such that the silicon particles are distributed throughout the composite material film.