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CN-122012040-A - Photo-thermal renewable carbon nano cage limited lithium chloride low-temperature energy storage composite material, preparation and application

CN122012040ACN 122012040 ACN122012040 ACN 122012040ACN-122012040-A

Abstract

The invention discloses a photo-thermal renewable carbon nano cage limit lithium chloride low-temperature energy storage composite material, and preparation and application thereof, and belongs to the technical field of energy storage materials. The composite material takes a carbon nano cage with a micropore-mesopore-macropore hierarchical structure as a carrier, loads a lithium chloride limit domain into a nano cavity and a pore canal of the composite material to form a stable composite structure, can effectively inhibit the leakage and agglomeration of lithium chloride, is prepared by a chemical vapor deposition method, is obtained by drying, vacuum impregnation, suction filtration and freeze drying shaping, has a simple and controllable process, can keep the advantages of grading Kong Chuanzhi of the carbon nano cage, can stably work in a relative humidity environment of 20-40 ℃ and 30% -60%, is suitable for capturing, storing and releasing low-grade heat energy of <100 ℃, can directly drive dehydration and regeneration through solar energy, has the advantages of high cycle stability and green regeneration, is suitable for adsorption type heat storage, solar photo-thermal energy storage and industrial waste heat recovery devices, and has significant industrial application value.

Inventors

  • HU ZHENG
  • ZHAO SONGHAO
  • ZHOU CHANGKAI
  • YANG LIJUN
  • WANG XIZHANG
  • WU QIANG
  • HUANG HONGWEN

Assignees

  • 南京大学

Dates

Publication Date
20260512
Application Date
20260203

Claims (10)

  1. 1. The carbon nano cage limit lithium chloride low-temperature energy storage composite material capable of being regenerated by light and heat is characterized in that the composite material takes a carbon nano cage as a carrier, lithium chloride as an active component, and the lithium chloride limit is loaded in a nano cavity and a pore canal of the carbon nano cage to form a lithium chloride@carbon nano cage composite structure.
  2. 2. The photo-thermal renewable carbon nano cage limit lithium chloride low-temperature energy storage composite material according to claim 1, wherein the composite material has broadband solar energy absorption and photo-thermal conversion capability, dehydration regeneration can be completed through solar energy driving, and low-grade heat energy with the temperature of less than 100 ℃ is suitable for a low-temperature thermal chemical energy storage working condition of a regenerative driving heat source.
  3. 3. The photo-thermal renewable carbon nanocage confinement lithium chloride low-temperature energy storage composite material is characterized in that the carbon nanocage is of a hierarchical porous structure with coexistence of micropores, mesopores and macropores, the specific surface area of the carbon nanocage is 2000-2200 m 2 ·g -1 , the pore volume is 3.8-4.3 cm 3 ·g -1 , the loading amount of lithium chloride in the composite material is 45-95 wt%, the specific surface area of the composite material is 50-650 m 2 ·g -1 , and the pore volume is 0.4-1.3 cm 3 ·g -1 .
  4. 4. A method for preparing a photo-thermal renewable carbon nano cage-limited lithium chloride low-temperature energy storage composite material according to any one of claims 1 to 3, comprising the following steps: 1) Preparing a carbon nano cage by adopting a chemical vapor deposition method and drying; 2) Preparing lithium chloride aqueous solution; 3) And (3) placing the dried carbon nano-cage into a closed container, vacuumizing to a pressure of less than 10 Pa, maintaining the vacuum state for 0.5-1 h to empty air in the cavity, injecting lithium chloride aqueous solution, vacuum-impregnating at room temperature for 8-16 h to enable the lithium chloride aqueous solution to fully permeate into nano cavities and pore channels of the carbon nano-cage, filtering, and freeze-drying to obtain the carbon nano-cage domain-limited lithium chloride low-temperature energy storage composite material.
  5. 5. The method for preparing the photo-thermal renewable carbon nano cage limited lithium chloride low-temperature energy storage composite material according to claim 4, wherein in the step 2), the mass fraction of the prepared lithium chloride aqueous solution is 5-20wt%, and the liquid-solid ratio of the lithium chloride aqueous solution to the carbon nano cage is 50 (0.1-1) mL/g.
  6. 6. The method for preparing the photo-thermal renewable carbon nano cage limited lithium chloride low-temperature energy storage composite material according to claim 4, wherein in the step 1), the drying temperature is 80-120 ℃ and the drying time is 4-16 h.
  7. 7. The method for preparing the photo-thermal renewable carbon nano-cage limited lithium chloride low-temperature energy storage composite material according to claim 5, wherein the mass fraction of the lithium chloride aqueous solution is 10 wt%, and the liquid-solid ratio of the lithium chloride aqueous solution to the carbon nano-cage is 50:0.1 mL/g.
  8. 8. The application of the photo-thermal renewable carbon nano cage limit lithium chloride low-temperature energy storage composite material according to any one of claims 1-3, wherein the composite material is used for a low-temperature thermal chemical energy storage system under different humidity environments, is suitable for capturing, storing and releasing low-grade heat energy at a temperature of less than 100 ℃, can absorb and store water in an environment with a relative humidity of 30% -60% in a temperature range of 20-40 ℃, and further can finish heat energy storage through hydration reaction, and can directly drive dehydration and regeneration through solar energy.
  9. 9. The use of claim 8, wherein the low grade heat energy comprises one or more of solar energy, industrial waste heat, geothermal.
  10. 10. The method according to claim 9, wherein the composite material has an equilibrium adsorption capacity of not less than 0.5 g/g in a low humidity environment of 30 ℃ and 30% relative humidity, and can be applied to one or more of an adsorption heat storage device, a solar photo-thermal energy storage system and an industrial waste heat recovery device.

Description

Photo-thermal renewable carbon nano cage limited lithium chloride low-temperature energy storage composite material, preparation and application Technical Field The invention belongs to the technical field of energy storage materials, and particularly relates to a photo-thermal renewable carbon nano cage limit lithium chloride low-temperature energy storage composite material, a preparation method of the composite material and application of the composite material in the fields of low-temperature thermal chemical energy storage, solar energy utilization and industrial waste heat recovery. Background Thermal energy storage is one of core technologies for solving the problem of mismatching between energy supply and demand time and space, and particularly has key effects on improving energy utilization efficiency and guaranteeing energy supply stability in areas with remarkable temperature fluctuation in day, night and season. In various heat energy storage technologies, the adsorption thermochemical energy storage has the outstanding advantages of high energy storage density, low heat loss in the storage stage, flexible and controllable operation and the like, and has wide application prospect in the fields of capturing and storing low-grade heat energy (below 100 ℃ such as solar energy and industrial waste heat), and becomes a research hot spot in the current energy field. The adsorption working medium is a core component of the adsorption type thermochemical energy storage system, and the comprehensive performance of the adsorption working medium directly determines key indexes such as energy storage density, running stability, power output and the like of the system. Among the numerous candidate working fluids, salt hydrate systems are becoming an important research point because of their high water absorption activity and controllable phase change properties, and lithium chloride (LiCl) is recognized as a potential preferred material in the field of thermal energy storage by virtue of its water absorption capacity far exceeding that of similar materials and its excellent theoretical energy density. The method has the advantages that the method is difficult to directly apply to actual engineering due to inherent defects of pure LiCl, large-scale landing is severely restricted by three major core technical bottlenecks, firstly, deliquescence leakage risk is prominent, deliquescence critical humidity of LiCl is extremely low, flowing salt solution is easy to form under conventional working conditions, working medium loss is caused, equipment corrosion and pipeline blockage are further caused, and finally, the energy storage system is stopped due to faults, secondly, circulation stability is extremely poor, particle agglomeration and solidification agglomeration of LiCl are easy to occur in repeated hydration-dehydration charge-discharge circulation, heat and mass transfer channel blockage is caused, performance is rapidly attenuated along with circulation times, long-term operation requirements cannot be met, thirdly, kinetic response is slow, adsorption-desorption reaction rate of pure LiCl is slow, rapid energy storage and release are difficult to realize, power density of the energy storage system is directly limited, and a high-efficiency energy scheduling scene cannot be adapted. These problems are superimposed on each other and become a major obstacle to the trend of pure LiCl-based heat storage materials for practical use. In order to solve the problems, the technical path adopted in the industry is to encapsulate salt hydrate such as LiCl and the like in a porous matrix to construct a composite adsorbent, and the stability of the material is improved by means of the physical constraint action of a porous carrier. Currently, silica gel, zeolite and various carbon-based framework materials have been widely explored for use in this scenario. Although the composite system relieves the leakage and agglomeration problems of pure LiCl to a certain extent, the composite system has the common limitation that the preparation process is complex and complicated, the production cost is high due to step redundancy, the industrialization landing is not facilitated, the performance balance contradiction is outstanding, the salt load is always required to be sacrificed for guaranteeing the stability of the carrier structure, the energy density of the composite material is greatly reduced, the carrier pore structure design is not matched with the rapid mass transfer requirement under high salt load, the internal diffusion resistance of the material is still obvious, the improvement effect of the adsorption dynamics performance is limited, and the essential deficiency of the LiCl-based material cannot be fundamentally solved. For example, literature "Composite sorbents"Li/Ca halogenides inside multi-wall carbon nano-tubes"for thermal energy storage, Sol. Energy Mater.Sol. Cells 155 (2016) 176-183." proposes a lithium c