Molybdenum Selenium Carbon Composite for Battery Stability

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Solution Overview

Problem

Lithium secondary batteries face challenges with large volume expansion of metals like silicon, tin, bismuth, gallium, and antimony, leading to defects and reduced energy density, and selenium elution in lithium selenium batteries affects charge/discharge characteristics.

Innovation Solution

A composite material with alternately stacked molybdenum and selenium metal compound layers and carbon layers, where the carbon layers inherently surround the metal compound layers, reducing selenium elution and improving conductivity, is fabricated using a method involving thermal treatments to enhance the stability and capacity of lithium ion and lithium selenium batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If metals like silicon, tin, bismuth, gallium, and antimony are used as negative electrode materials to increase capacity, then the battery capacity increases 5 to 10 times compared to graphite, but large volume expansion occurs causing electrode defects

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrode stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent embeds metal particles (silicon, tin, bismuth, gallium, or antimony) inside hollow carbon spheres, creating a nested structure where the metal is contained within the carbon shell. This nesting approach allows the high-capacity metal to be protected from volume expansion issues while maintaining its electrochemical activity, resolving the contradiction between capacity and stability

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent uses hollow carbon spheres as flexible containers for the metal particles. The carbon shell acts as a flexible buffer that can accommodate volume changes of the metal during lithiation/delithiation cycles, preventing electrode degradation while maintaining structural integrity throughout charge-discharge cycles

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If selenium is used as positive electrode material to increase capacity, then battery capacity improves, but selenium elution occurs affecting charge/discharge characteristics

Engineering Contradiction:

Improvebattery capacityVSAvoidcharge/discharge performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent coats selenium particles with a carbon shell layer, creating a protective barrier that prevents selenium from leaching into the electrolyte during battery operation. This carbon coating maintains selenium's high capacity while eliminating elution problems that degrade charge/discharge characteristics

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent creates composite structures combining selenium with carbon materials, forming selenium-carbon composite particles. This composite approach leverages selenium's high capacity while the carbon component provides structural stability and prevents selenium dissolution, achieving both high capacity and reliable charge/discharge performance

Inventive Principle:

Principle #40Composite materials

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 composite material enhances the capacity, stability, and life characteristics of lithium ion and lithium selenium batteries by minimizing selenium elution and improving conductivity, resulting in high-capacity and long-life batteries suitable for electric vehicles and energy storage systems.

Implementation Method 1

the carbon layers inherently surround the metal compound layers, reducing selenium elution

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

improving conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11664494B2Composite material including selenium, method of fabricating the same, lithium ion and lithium selenium secondary batteries including the same, and lithium ion capacitor including the same

Publication Date: 2023.05.30 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY

AI summary

A composite material is provided. The composite material includes carbon layers and metal compound layers alternately and repeatedly stacked. Each of the metal compound layers includes molybdenum and selenium. When the composite material is used as a positive active material for a lithium selenium secondary battery, selenium is separated from the metal compound layer through a preliminary charge/discharge process. In addition, the composite material may be used as negative active materials of a lithium ion battery and a lithium ion capacitor. Furthermore, the composite material may be used as an active material of a positive electrode of the lithium selenium secondary battery.