Silicon Pillared Particles for Lithium-Ion Anodes
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Solution Overview
Problem
Conventional lithium-ion batteries face challenges in storing more energy per unit mass and volume, with silicon-based anode materials experiencing significant structural changes and mechanical stress due to lithium ion insertion and extraction, leading to potential cracking and disintegration.
Innovation Solution
The development of pillared particles with a core and spaced-apart pillars, where the pillars are made of electroactive materials like silicon, providing increased surface area and accommodating volume expansion without mechanical stress, and the pillars are spaced to prevent contact loss and enhance lithium ion insertion and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active anode material is used to increase energy storage capacity, then the maximum capacity increases substantially, but the structural stability deteriorates due to substantial expansion and mechanical stress during lithium ion insertion
Solution Approach 1:
The silicon particle is segmented into a core region and multiple pillar structures extending from the core. This segmentation allows the silicon to be divided into smaller functional units that can independently accommodate volume changes, preventing catastrophic structural failure while maintaining high lithium storage capacity.
Solution Approach 2:
The invention employs a nested structure where pillars are formed within or extending from the core particle. The pillars act as internal expansion spaces that can accommodate volume changes during lithiation/delithiation cycles, allowing the core to expand and contract without experiencing excessive mechanical stress that would lead to cracking.
2Area of moving object
If silicon particles are etched to form pillars, then the surface area increases for better lithium ion insertion, but the mechanical strength decreases due to material removal
Solution Approach 1:
The etching process is applied locally to specific regions of the silicon particle to form pillars, rather than uniformly removing material. This localized modification increases surface area in critical regions for lithium ion insertion while preserving the bulk structural integrity of the particle, maintaining mechanical strength where it is most needed.
Solution Approach 2:
The pillared silicon structure can be viewed as a composite where the core provides mechanical strength and the pillars provide surface area for electrochemical activity. This composite architecture combines the benefits of high surface area with maintained structural integrity, as the core supports the pillars while the pillars enhance lithium ion insertion capability.
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 design enhances the specific reversible charge capacity and cycle life of lithium-ion batteries by allowing for greater lithium storage capacity per unit mass and volume while maintaining structural integrity, reducing mechanical stress and electrolyte loss.
Implementation Method 1
the process of insertion of metal ions into silicon results in substantial structural changes, accompanied by substantial expansion
Implementation Method 2
a material which is able to insert into its structure, and release therefrom, metal ions such as lithium, sodium, potassium, calcium or magnesium during the respective charging phase and discharging phase of a battery
Data Source
Figure 1~2B
Figure 2C~2G
Figure 3A~3B
AI summary
A powder comprising pillared particles for use as an active component of a metal ion battery, the pillared particles comprising a particle core and a plurality of pillars extending from the particle core, wherein the pillared particles comprise silicon or tin, wherein the pillar mass fraction PMF is greater than or equal to 5%, and wherein a BET/PMF ratio of the powder is less than 3, wherein BET is in m2/g, and PMF = [(Total mass of pillars extending from the particle core) / (Total mass of pillared particle)] x 100.