Silicon-Tin Anode Layering for Stable Solid-State Battery Cycling
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Solution Overview
Problem
Current solid-state battery technologies face challenges with the high volume expansion of silicon and tin anode materials during lithiation, leading to capacity decay and issues with the solid-electrolyte interphase (SEI) layer when used with liquid electrolytes.
Innovation Solution
The use of silicon and/or tin in specific layered configurations within solid-state batteries, where silicon is maintained in contact with softer tin layers, and the solid electrolyte only contacts the tin in a single plane, reducing side reactions and maintaining ion and electron conduction paths during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon and tin are used as anode materials in solid-state batteries, then the battery capacity is improved, but the volume expansion during lithiation causes capacity decay and SEI layer issues
Solution Approach 1:
The patent applies this principle by using a flexible polymer electrolyte that can accommodate the volume expansion of silicon and tin anode materials during lithiation. The polymer electrolyte's flexible nature allows it to maintain contact and ionic conduction paths despite the anode's dimensional changes, preventing capacity decay and SEI layer formation issues.
Solution Approach 2:
The patent uses composite materials by combining silicon and tin in specific ratios (e.g., Si:Sn = 1:3 to 1:10) within the anode structure. This composite approach leverages the high capacity of both materials while the polymer electrolyte acts as a binding matrix that accommodates their expansion, achieving both high capacity and cycling stability.
2Quantity of substance
If silicon and tin anode materials are used with liquid electrolytes, then high capacity is achieved, but side reactions occur at the solid-electrolyte interphase
Solution Approach 1:
The patent applies this principle by changing the electrolyte from liquid to solid polymer form. This parameter change eliminates the side reactions characteristic of liquid electrolytes while maintaining ionic conductivity. The solid polymer electrolyte provides a stable interface with the silicon-tin anode, preventing harmful SEI layer formation and enabling sustained high capacity.
3Quantity of substance
If silicon and tin are used in high proportions for high capacity, then the battery capacity increases, but the volume expansion and capacity decay worsen
Solution Approach 1:
The patent uses the polymer electrolyte as an intermediary material between the silicon-tin anode and the rest of the battery. This intermediary accommodates the volume expansion of the high-proportion silicon-tin mixture during lithiation, maintaining structural stability and preventing capacity decay while allowing the anode to operate at high capacity levels.
4Reliability
If complex layered configurations are used to maintain contact during cycling, then cycling stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies this principle by making the polymer electrolyte serve multiple functions: it acts as the ionic conductor, the binding matrix for the silicon-tin particles, the flexible shell that accommodates volume expansion, and the interface layer that prevents side reactions. This multi-functionality simplifies the overall structure compared to complex layered configurations while maintaining excellent cycling stability.
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 configuration enhances the cycling stability and coulombic efficiency of solid-state batteries by minimizing capacity loss and maintaining stable resistance, while also reducing the complexity and cost of manufacturing.
Implementation Method 1
maintaining ion and electron conduction paths during cycling
Implementation Method 2
silicon is maintained in contact with softer tin layers
Data Source
AI summary
A solid-state battery includes an anode material including silicon or tin. The anode material may include silicon and/or tin in various forms including layers or intermixed particles of various phases and crystallinity.