Polyethylene Insulation with Core-Shell Quantum Dots for HVDC Cables

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Solution Overview

Problem

The insulation performance of high-voltage direct current (HVDC) cables is compromised by high temperature and strong electric fields due to increased conductivity and space charge accumulation, leading to potential insulation failure.

Innovation Solution

An insulating material comprising polyethylene, core-shell quantum dots, a peroxide cross-linking agent, and an antioxidant is developed, where the core-shell quantum dot interface forms a n-n type semiconductor heterostructure, limiting carrier migration and inhibiting space charge accumulation through energy band structure modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyethylene is used as insulation material for HVDC cable, then desirable electrical resistance is achieved, but conductivity increases exponentially with temperature causing electric field reversal and space charge accumulation

Engineering Contradiction:

Improveinsulation performanceVSAvoidconductivity increase under high temperature and strong electric field

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses composite materials by incorporating core-shell quantum dots into polyethylene matrix. The quantum dots with specific band gap structure (core: CdSe or ZnSe, shell: ZnS) form a composite insulation material that combines the excellent electrical resistance of polyethylene with the carrier confinement capability of quantum dots, resolving the contradiction between maintaining electrical resistance and preventing conductivity increase under high temperature and strong electric fields

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating heterostructure interfaces within the quantum dots (core-shell structure with different band gaps). The core layer and shell layer have different semiconductor properties that create localized energy band structures, forming potential wells that selectively confine carriers at specific locations (interfaces), thereby locally addressing the conductivity issue without affecting the overall polyethylene matrix properties

Inventive Principle:

Principle #3Local quality

2Strength

If cross-linking reaction is performed on polyethylene to form cross-linked polyethylene, then heat resistance and mechanical properties are improved, but space charge accumulation occurs under HVDC stress leading to insulation failure

Engineering Contradiction:

Improveheat resistance and mechanical propertiesVSAvoidspace charge accumulation under HVDC stress

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent combines cross-linked polyethylene with core-shell quantum dots to create a composite material that maintains the heat resistance and mechanical properties of cross-linked polyethylene while adding the space charge suppression capability of quantum dots. The quantum dots act as space charge traps that prevent accumulation, resolving the contradiction between structural strength and electrical stability under HVDC stress

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The quantum dots serve as an intermediary between the cross-linked polyethylene matrix and the electric field. They intercept and confine charge carriers before they can accumulate in the bulk material, acting as a mediating layer that prevents the harmful effect of space charge accumulation while allowing the cross-linked structure to provide mechanical and thermal support

Inventive Principle:

Principle #24Intermediary (Mediator)

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 material maintains low electrical conductivity and suppresses space charge accumulation, enhancing insulation performance under high temperature and strong electric fields, thereby improving the reliability and safety of HVDC cables.

Implementation Method 1

a contact interface formed between a core layer and a shell layer of the core-shell quantum dot belongs to n-n type semiconductor heterostructure contact

Methodology Applied

Scientific Effectn-n type semiconductor heterostructure contact:

Implementation Method 2

an energy band structure of the core layer bends downward while an energy band structure of the shell layer bends upward

Methodology Applied

Scientific EffectEnergy band structure bending:

Implementation Method 3

A core-shell interface of the core-shell quantum dot itself provides a confinement effect on electron carriers, while an interface between the shell layer and an insulating matrix provides a confinement effect on hole carriers

Methodology Applied

Scientific EffectConfinement effect:

Implementation Method 4

Electron carriers at the bottom of a conduction band may be limited by a core-shell interface and can have difficulty in continuing to migrate

Methodology Applied

Scientific EffectCarrier migration limitation:

Implementation Method 5

the insulating material exhibits a low electrical conductivity under high temperature and strong electric fields

Methodology Applied

Scientific EffectConductivity reduction:

Data Source

PatentUS12516175B2Insulating material, and preparation method and use thereof

Publication Date: 2026.01.06 TIANJIN UNIV

AI summary

Provided are an insulating material, and a preparation method and use thereof. The insulation material includes the following components in parts by mass: 100 parts of polyethylene, 0.01 parts to 1 part of a core-shell quantum dot, 0.5 parts to 2 parts of a peroxide cross-linking agent, and 0.5 parts to 2 parts of an antioxidant.