Multilayer Porous Anode Materials for Silicon Capacity Retention
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Solution Overview
Problem
Rechargeable metal-ion batteries, particularly lithium-ion batteries, face challenges in maintaining high gravimetric and volumetric capacities due to mechanical stress and solid electrolyte interphase (SEI) formation issues with silicon anode materials, leading to capacity loss over charge-discharge cycles.
Innovation Solution
A multilayer composite particle structure is developed, comprising a porous carbon framework with alternating layers of electroactive material and interlayer material, deposited using chemical vapor infiltration, to mitigate volume expansion and reduce SEI formation, enhancing mechanical buffering and conductive performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as anode material to achieve high capacity, then gravimetric and volumetric capacities are improved, but mechanical stress and volume expansion cause capacity loss over cycles
Solution Approach 1:
The silicon anode material is divided into fine particles with cross-section dimensions below 150 nm, which are then deposited within the pore structure of a porous carrier material. This segmentation reduces the mechanical stress and volume expansion problems associated with bulk silicon while maintaining high capacity.
Solution Approach 2:
The silicon-based electroactive material is nested within the pore structure of a porous carrier material framework. The carrier material provides a supportive matrix that accommodates the volume changes of silicon during charging and discharging, while the silicon particles provide high capacity.
2Reliability
If nanoscale silicon particles are used to reduce volume change stress, then capacity retention is improved, but manufacturing difficulty and handling challenges increase
Solution Approach 1:
The porous carrier material acts as an intermediary that facilitates the handling and processing of nanoscale silicon particles. The carrier material provides a robust framework that enables easy handling, storage, and electrode fabrication while the silicon particles remain protected within the pore structure.
3Ease of manufacture
If silicon films are used to avoid handling difficulties, then ease of manufacture is improved, but bulk capacity is insufficient
Solution Approach 1:
The invention uses a porous carrier material with a three-dimensional framework that provides both mechanical robustness for easy handling and sufficient pore volume to accommodate a high loading of silicon-based electroactive material, thereby achieving both ease of manufacture and high bulk capacity.
4Reliability
If high surface area silicon structures are used to accommodate volume changes, then mechanical tolerance is improved, but SEI formation increases leading to capacity loss
Solution Approach 1:
The silicon-based electroactive material is deposited within the internal pore structure of the carrier material, creating a localized configuration where the high surface area benefits are achieved only where needed for mechanical tolerance, while the overall particle surface area remains limited to reduce SEI formation.
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 multilayer structure significantly improves the reversible capacity retention and rate performance of silicon-based anodes by reducing mechanical stress and SEI formation, maintaining high capacity over multiple cycles while minimizing initial capacity loss.
Implementation Method 1
a material which is capable of inserting and releasing metal ions during the charging and discharging of a battery
Implementation Method 2
deposited using chemical vapor infiltration
Data Source
AI summary
This invention relates in general to electroactive materials and a process for the preparation thereof. The electroactive particles comprise a comprise a porous particle framework, wherein the total pore volume of pores having pore diameter in the range from 3.5 to 100 nm is in the range from 0.3 to 2.4 cm3 per gram of the porous particle framework. The pores of the porous particle are at least partially occupied by a multilayer coating that is disposed on the internal pore surfaces of the porous particle framework. The multilayer coating comprises at least a first electroactive material layer, a second electroactive material layer, and a first interlayer material disposed between the first and second electroactive material layers.