Construction Of Heterogeneous Interfaces For Graphdiyne-Based Electrochemical Energy Storage Materials

Graphdiyne（GDY）is a new carbon allotrope composed of sp and sp²hybrid carbon with China’s own intellectual property rights.Its unique chemical structure,abundant chemical bonds,large two-dimensional conjugate plane,uniform distribution of holes and surface charge distribution and other characteristics make it have many excellent physical and chemical properties.It is widely used in many fields such as electrochemical energy storage,catalysis,biology,medicine,photoelectric conversion,electronic information and so on,showing excellent performance and great application potential.This paper is based on the unique chemical and electronic structural properties of GDY.Aiming at the key scientific problems in the field of energy storage,such as the volume expansion of the electrode structure,metal dissolution,electrode interface instability and so on,a series of high-performance GDY-based electrode materials are prepared through the design of GDY-based heterogeneous interface.The electrochemical reaction process of GDY-based heterogeneous interface during charging and discharging process of battery was studied,and the new mechanism of GDY-based heterogeneous interface to improve electrode performance was revealed.A high-performance energy storage device based on GDY was obtained,and a new application of GDY efficient electrochemical energy storage was realized.The main research contents and innovation points are as follows.（1）Suppressing the irreversible interfacial reactions is an important scientific bottleneck in the development of stable high-energy-density lithium-ion battery.In this paper,the method of modifying the interface of high-voltage cathode material LiNi_0.5Mn_1.5O₄（LNMO）by GDY has been developed,which inhibits the side reaction of the interface of cathode material LNMO under high working voltage.The chemical capture of HF is realized by using the high selectivity of GDY to HF,which effectively inhibits the dissolution of Mn and Ni,and greatly improves the interface stability of the cathode material.After 70 cycles,the capacity retention increased from 27%of the pristine LNMO to 97.5%of GDY@LNMO,achieving high coulomb efficiency and long cycle stability,revealing the great advantage of GDY in stabilizing and protecting the electrode interface to obtain long-life and high energy density electrodes.（2）Before the intercalation reaction of the host electrodes,the desolvation of ions in the interface is an essential step,which directly affects the performance of battery.This paper has deeply studied the lithiophilic of GDY’s sp-C,and revealed that the activation energy of the Li⁺desolvation process at the interface is reduced with the help of lithiophilic of GDY’s sp-C.The high-areal-density of in-plane cavities on GDY forms a large number of stable transportation channels of Li⁺that efficiently promotes the kinetic behavior of Li⁺and interfacial charge transfer.Especially at 3 C,the capacity of the GDY@graphite electrode can reach 75 m Ah g^-1,while the capacity of pristine graphite electrode is only 20 m Ah g^-1.Additionaly,the permeation and atomic-level selectivity of GDY cavities effectively prevent the co-intercalation of solvent molecules in graphite,thus the interfacial parasitic reactions of electrolyte are avoided.（3）The fast charging and discharging process of lithium-ion batteries has always been an important scientific issue of great concern.This paper starts from the construction of working electrode structure,a planar stacking structure unit of graphdiyne/black phosphorus/graphdiyne（GDY/BP/GDY）was designed and prepared.The GDY@BP electrode of Lithium-ion batteries（LIB）with multi-level layered structure was obtained by assembling GDY/BP/GDY planar stacking structure units.The built-in electric field formed by GDY in GDY/BP/GDY unit is conducive to the rapid transport of electrons and ions in the interface of different electrode materials.The GDY film also plays a buffer and protection role on the BP layer,effectively suppressing the capacity attenuation caused by the huge volume change of BP during the charging and discharging process.The GDY@BP electrode has a high specific capacity of 1418.8 m A h g^-1at a current density of 0.1 A g^-1.At a current density of 10 A g^-1,the GDY@BP electrode still has a specific capacity of 391.7 m A h g^-1after 5000 cycles.The excellent rate performance and cycle stability of the GDY@BP electrode confirm the important role and advantages of the design electrode structure in improving the electrode performance.（4）The improvement of catalyst utilization and stability is an important bottleneck of catalyst application and battery performance.In this paper,the method of GDY supported IrO_xclusters has been developed,and efficient dual-functional electrocatalysts have been obtained.Using the anchoring effect of GDY on metal atoms,uniform IrO_xclusters were prepared by simple hydrothermal reaction on the basis of GDY-modified carbon cloth（CC）.Not only avoids the use of polymer adhesive,but also the conductivity of GDY is conducive to faster charge transfer behavior.Acquired IrO_x@GDY@CC composite shows excellent dual functional characteristics of oxygen reduction reaction and oxygen evolution reaction,and can be used for high-efficiency zinc-air battery.The zinc-air battery with IrO_x@GDY@CC as air cathode can operate stably for more than 1000 hours（1500 cycles）at a high current density of 5 m A cm^-2.