Graphene Oxide Salt Hydrate Heat Storage Phase Separation
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Solution Overview
Problem
Salt hydrates used in heat storage materials tend to undergo phase separation into anhydride and water during repeated melting and solidification, leading to a lower heat storage density in the resulting supernatant and residual liquid, which affects the efficiency of temperature control in batteries.
Innovation Solution
Incorporating graphene oxide into a heat storage material comprising a salt hydrate and a supercooling inhibitor, such as sodium carbonate, to inhibit phase separation, while using potassium nitrate to adjust the melting point and ensure a high heat storage density, with optimal graphene oxide and sodium carbonate content ranging from 0.2% to 0.4% and 0.5% to 1.0% by weight, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If salt hydrate is used as heat storage material, then high heat storage density is achieved, but phase separation into anhydride and water occurs during repeated melting and solidification
Solution Approach 1:
Graphene oxide acts as an intermediary substance between water and salt anhydride, preventing their direct contact and interaction that would lead to phase separation. The graphene oxide forms a physical barrier that maintains the homogeneous mixture of salt hydrate components during thermal cycling, thereby preserving both heat storage density and compositional stability.
Solution Approach 2:
The invention creates a composite heat storage material system consisting of salt hydrate, supercooling inhibitor, and graphene oxide. This composite structure combines the high heat storage capacity of salt hydrate with the phase separation prevention properties of graphene oxide, achieving both high heat storage density and compositional stability simultaneously.
2Reliability
If supercooling inhibitor is added to promote solidification, then solidification is enhanced, but excessive addition may affect heat storage density
Solution Approach 1:
The invention optimizes the concentration parameter of the supercooling inhibitor within a specific range (0.5-1.0 wt%) to achieve the desired solidification promotion effect while minimizing the negative impact on heat storage density. By precisely controlling this parameter, the system maintains reliability through enhanced solidification without significantly compromising the heat storage capacity.
3Stability of the object's composition
If graphene oxide content is increased to inhibit phase separation, then phase separation inhibition is improved, but viscosity increases excessively
Solution Approach 1:
The invention optimizes the concentration parameter of graphene oxide within a specific range (0.2-0.4 wt%) to achieve effective phase separation inhibition while keeping viscosity at acceptable levels. This parameter optimization ensures that the material remains workable and easy to handle while maintaining compositional stability during thermal cycling.
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 addition of graphene oxide effectively inhibits phase separation, maintaining a high heat storage density and preventing supercooling, ensuring reliable temperature control for batteries by promoting solidification and maintaining uniform mixing without excessive viscosity.
Implementation Method 1
graphene oxide can inhibit the phase separation of the salt hydrate
Implementation Method 2
heat storage materials can be melted by heat from batteries, for example, at high temperatures so that they will store latent heat
Implementation Method 3
some heat storage materials can be melted by heat from batteries
Implementation Method 4
a supercooling inhibitor that promotes solidification of the salt hydrate
Data Source
AI summary
An object of the present invention is to inhibit the phase separation of a salt hydrate used as a main component of a heat storage material. The inventors have made the present invention based on findings that when added to a heat storage material including a salt hydrate and a supercooling inhibitor, graphene oxide can inhibit the phase separation of the salt hydrate. The present invention is directed to a heat storage material including: a salt hydrate as a main component; a supercooling inhibitor that promotes solidification of the salt hydrate; and graphene oxide. The technical features help to inhibit the phase separation of salt hydrates.