Polymer-Embedded Silicon Electrode Structures for Cycle Life
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Solution Overview
Problem
High-capacity materials like silicon experience significant volume changes during charge-discharge cycling, leading to pulverization, irreversible capacity loss, and poor cycle life in battery electrodes, limiting their application.
Innovation Solution
Composite battery electrode structures are formed with active electrode material structures and polymer structures, where at least a portion of the polymer structures protrude into or are enclosed by the active electrode material structures, providing internal elastic adhesion and support, and are synthesized using low-temperature deposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity materials like silicon are used as active electrode materials, then the battery capacity increases, but the electrode structure undergoes significant volume changes during cycling leading to pulverization and poor cycle life
Solution Approach 1:
The patent embeds active electrode material structures inside polymer structures, creating a nested configuration where the active material is contained within a protective polymer matrix. This nesting approach allows the high-capacity material to maintain its volumetric expansion while the outer polymer layer absorbs mechanical stress and prevents pulverization, thereby maintaining both high capacity and improved cycle life.
Solution Approach 2:
The patent creates composite electrode structures combining active electrode materials (such as silicon, tin, or germanium) with polymer materials. This composite structure leverages the high capacity of the active material while the polymer component provides mechanical stability and flexibility to accommodate volume changes. The composite design enables the electrode to withstand repeated cycling without pulverization, resolving the contradiction between high capacity and cycle life.
2Strength
If the size of active material structures is reduced to decrease stress during volume changes, then mechanical stability improves, but supporting and interconnecting many small individual structures becomes challenging
Solution Approach 1:
The patent combines multiple small active material structures within a single polymer structure, merging their support requirements into one unified matrix. This approach eliminates the need for separate support structures for each small particle, as the polymer matrix collectively supports and interconnects all embedded active material structures, thereby reducing overall device complexity while maintaining mechanical stability.
Solution Approach 2:
The polymer structure serves as an intermediary that bridges and interconnects multiple small active material structures. Rather than requiring direct support infrastructure for each particle, the polymer matrix acts as a mediating network that provides mechanical support, electrical connectivity, and structural integrity across all embedded active material structures, simplifying the overall electrode architecture.
3Stability of the object's composition
If rigid support matrices are used to mechanically limit expansion of active material structures, then structural stability improves, but the support matrices add to electrode weight and are challenging to form
Solution Approach 1:
The patent employs flexible polymer structures instead of rigid support matrices to contain and support active material structures. These polymer shells are sufficiently flexible to accommodate volumetric expansion during lithium insertion without providing excessive mechanical resistance, thereby maintaining structural stability while minimizing additional weight. The thin-film nature of the polymer layers further reduces weight addition compared to bulk rigid supports.
Solution Approach 2:
The patent changes the mechanical parameters of the support structure by using polymers with appropriate elasticity and compliance rather than rigid materials. This parameter change allows the support structure to dynamically adapt to volume changes during cycling, providing stability when needed while avoiding the weight penalty and formation challenges associated with rigid matrices. The polymer's mechanical properties can be tuned to match the expansion characteristics of the active material.
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 structures maintain structural integrity during cycling, accommodate volume changes, and prevent pulverization, enhancing cycle life and performance.
Implementation Method 1
polymer structures, which contain repeating molecular units... at least a first portion of the polymer structures at least partially protrudes into and is at least partially surrounded by at least a second portion of the active electrode material structures
Implementation Method 2
Composite battery electrode structures may be formed using low-temperature deposition techniques, such as solvent-thermal synthesis, direct chemical reduction, and electrochemical deposition
Data Source
AI summary
Described herein are composite battery electrode structures and methods of forming such structures. Composite battery electrode structures comprise active electrode material structures and polymer structures such that at least a portion of the polymer structures at least partially protrudes into some of the high capacity structures. Some of these polymer structures may be fully enclosed by the active electrode material structures. Other polymer structures may only partially extend inside the active electrode material structures. Furthermore, additional polymer structures may be bound to the external surface of the active electrode material structures. Composite battery electrode structures may be formed using low-temperature deposition techniques, such as solvent-thermal synthesis, direct chemical reduction, and electrochemical deposition. More specifically, composite battery electrode structures may be formed from a solution comprising active electrode material precursors and polymer precursors, e.g., dissolved polymers, monomers, and/or conductive polymers electrically coupled to the working electrodes.