Porous Amorphous Lithium Storage Particles for Battery Cycling Stability
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Solution Overview
Problem
High specific capacity negative electrode materials like silicon in lithium ion batteries experience large volume expansion and contraction during charging/discharging, leading to mechanical degradation and poor cycling stability.
Innovation Solution
The method involves forming porous, amorphous lithium storage material particles by inducing phase separation in composite particles of a lithium storage material and an immiscible material, followed by chemical etching to create particles with a large surface area and sufficient free space to accommodate volume changes, using techniques such as rapid solidification and milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high specific capacity negative electrode materials like silicon are used, then battery capacity is improved, but mechanical degradation occurs due to large volume expansion and contraction
Solution Approach 1:
The patent applies porous materials by creating a porous structure within the negative electrode material matrix. This porous structure provides expansion space for volume changes during lithium insertion/extraction, accommodating the large volume expansion and contraction of high capacity materials like silicon without causing mechanical degradation, thereby maintaining cycling stability while preserving high battery capacity.
Solution Approach 2:
The patent applies composite materials by combining different materials to form a composite negative electrode structure. This composite structure integrates high capacity materials (e.g., silicon) with other materials that provide structural stability and accommodate volume changes, enabling the electrode to maintain both high capacity and good cycling stability through synergistic effects of the constituent materials.
2Strength
If dense structure materials are used to maintain structural integrity, then mechanical strength is improved, but volume change accommodation space is reduced
Solution Approach 1:
The patent resolves this contradiction by introducing a porous structure that provides internal void space within the material matrix. This porous architecture allows the material to accommodate significant volume changes during electrochemical cycling while the surrounding matrix maintains structural integrity, effectively decoupling the requirements for mechanical strength and volume accommodation.
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 resulting particles improve cycling stability and extend the life of lithium ion batteries by allowing them to withstand multiple charge/discharge cycles without mechanical degradation.
Implementation Method 1
Phase separation is induced within the composite particles to precipitate out the amorphous phase lithium storage material
Implementation Method 2
The immiscible material is chemically etched from the phase separated composite particles to form porous, amorphous lithium storage material particles
Data Source
AI summary
Porous, amorphous lithium storage materials and a method for making these materials are disclosed herein. In an example of the method, composite particles of a lithium storage material in an amorphous phase and a material that is immiscible with the lithium storage material are prepared. Phase separation is induced within the composite particles to precipitate out the amorphous phase lithium storage material and form phase separated composite particles. The immiscible material is chemically etched from the phase separated composite particles to form porous, amorphous lithium storage material particles.