Yolk-Shell Silicon Anode for Battery Cycle Life
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Solution Overview
Problem
Conventional anode materials for batteries lack high energy density and long cycle life, and existing methods for forming structured materials are inefficient in creating micron-sized particles with submicron-sized electroactive materials and cavities.
Innovation Solution
A yolk-shell-structured material is created by forming submicron-sized particles of a first material with a micron-sized shell made of a second material, where the shell encloses a cavity, achieved through processes like mechano-fusion and thermal treatment, allowing for the formation of an anode material with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anode materials are used, then manufacturing is simple, but energy density and cycle life are insufficient
Solution Approach 1:
The anode material is segmented into submicron-sized particles enclosed within a micron-sized shell, creating a yolk-shell structure. This segmentation allows the electroactive material to be divided into smaller units that can independently expand and contract, improving cycle life while maintaining manageable overall structure
Solution Approach 2:
The submicron-sized particles are nested within the micron-sized shell, forming a yolk-shell configuration. This nested structure provides both the complexity needed for high energy density and the organizational framework that enables long cycle life through controlled expansion spaces
2Quantity of substance
If submicron-sized electroactive particles are incorporated, then energy density increases, but manufacturing efficiency decreases
Solution Approach 1:
The micron-sized shell is formed first as a container structure, and then submicron-sized particles are introduced into this pre-formed shell. This preliminary action simplifies manufacturing by avoiding the need to directly assemble complex submicron structures, thereby improving productivity while maintaining high energy density
Solution Approach 2:
The micron-sized shell acts as an intermediary structure that facilitates the incorporation of submicron-sized particles. This intermediate framework enables efficient manufacturing processes while accommodating the high quantity of electroactive material needed for high energy density
3Volume of moving object
If micron-sized particles are formed, then tap density improves, but cavity formation complexity increases
Solution Approach 1:
A core material is first used to form the micron-sized particle structure, and then this core is removed to create the cavity. This extraction approach simplifies cavity formation by using a sacrificial template rather than attempting to directly create complex hollow structures, thereby improving tap density while managing manufacturing complexity
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 yolk-shell-structured material exhibits high gravimetric energy density and long cycle life, making it suitable for battery anodes with improved tap density and processability, and can be applied in various fields including electrode materials and hydrogen storage.
Implementation Method 1
at least one cavity enclosed by a micron-sized shell made of a second material which is different from the first material
Implementation Method 2
The yolk-shell-structured material exhibits high gravimetric energy density and long cycle life
Data Source
AI summary
A yolk-shell-structured material (16, 59, 59a, 74) is disclosed as including a plurality of silicon nano-particles (12, 54, 54a, 62) and a cavity (16, 60, 80, 84) enclosed by a micron-sized shell (18, 72) made of carbon nano-particles (14, 56, 58). A method of forming a yolk-shell-structured material with silicon nano-particles (12) and a cavity (16) enclosed by a micron-sized shell (18) made of carbon nano-particles (14) is disclosed as including (a) providing a micron-sized cornstarch core (10), (b) forming a layer of nano silicon-particle (12) on the cornstarch core (10), (c) forming a micron-sized shell (18) of carbon nano-particles (14) on the layer of nano silicon-particle (12), and (d) removing the cornstarch core (10) by heating.