Silicon Inert Element Structures Mitigate Swelling
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Solution Overview
Problem
High-capacity materials like silicon for lithium-ion batteries experience significant volume changes during charge-discharge cycling, leading to pulverization and irreversible capacity losses.
Innovation Solution
Electrochemically active-material structures comprising silicon and one or more inert elements, such as hydrogen, carbon, nitrogen, and chlorine, are chemically or atomically dispersed to mitigate volume changes and maintain electrode integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity materials like silicon are used to increase energy density, then gravimetric and volumetric capacities are improved, but volume changes during cycling cause pulverization and loss of electrical connections
Solution Approach 1:
The patent creates composite material structures where silicon particles are embedded within a carbon matrix. The carbon component provides mechanical stability and conductivity while the silicon provides high capacity, resolving the contradiction between capacity and structural integrity during cycling
Solution Approach 2:
The patent employs carbon-coated shells surrounding silicon particles. These flexible carbon shells accommodate the volume expansion and contraction of silicon during lithiation and delithiation, preventing pulverization while maintaining electrical connectivity
2Ease of manufacture
If conventional integration methods are used for high-capacity materials, then electrode formation is simplified, but irreversible capacity losses and excessive SEI formation occur
Solution Approach 1:
The patent applies carbon coating specifically to the surface and interface regions of silicon particles, providing localized protection where SEI formation occurs most aggressively, while maintaining the high-capacity bulk silicon structure
Solution Approach 2:
The carbon matrix acts as an intermediary between the silicon particles and the electrolyte, providing a stable interface that reduces excessive SEI formation on silicon surfaces while maintaining electrical conductivity
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 dispersion of inert elements in silicon-based structures reduces swelling, enhances mechanical stability, and extends the cycle life of lithium-ion batteries by minimizing irreversible capacity losses.
Implementation Method 1
these inert elements help to mitigate silicon swelling by operating as a mechanical buffer
Implementation Method 2
these inert elements help to mitigate silicon swelling by operating as a mechanical buffer, support structure, and/or additional conductive pathways
Implementation Method 3
reacting the one or more precursors using reaction conditions that induce formation of the electrochemically active-material structures by simultaneously extracting the silicon and the one or more inert elements
Implementation Method 4
the reaction conditions induce one or both of a chemical reaction and a electrochemical reaction of the one or more precursors
Data Source
AI summary
Described herein are electrochemically active-material structures comprising silicon and one or more inert elements, chemically and/or atomically dispersed in these electrochemically active-material structures. Also described are negative battery electrodes and lithium-ion electrochemical cells comprising such electrochemically active-material structures as well as methods of fabricating such structures, electrodes, and lithium-ion electrochemical cells. Some examples of atomically-dispersed inert elements include, but are not limited to, hydrogen (H), carbon (C), nitrogen (N), and chlorine (Cl). Unlike silicon, inert elements do not interact with lithium at an operating voltage of the negative battery electrode and therefore do not contribute to the overall cell capacity. At the same time, these inert elements help to mitigate silicon swelling by operating as a mechanical buffer, support structure, and/or additional conductive pathways. Such electrochemically active-material structures can be formed by reacting (chemically or electrochemically) one or more precursors that include silicon and corresponding inert elements.