Size Control Of Organic Electrode Material And Its Application In Sodium And Aluminum Ion Batteries

The development of clean energy systems,electric vehicles and portable electronic devices has brought new development opportunities to energy storage technology.As a widely used energy storage technology,lithium-ion batteries（LIBs）have made remarkable achievements.With the increasing requirements for energy storage technology,higher safety and endurance are required for LIBs.However,the current development of LIBs have encountered a bottleneck,and the energy density still needs to be further improved,so it’s necessary to find higher-capacity electrode materials,use solid electrolytes,or find other alternative battery technologies.In addition,the crust reserves of lithium metal resources are low,and the large demand for LIBs has exacerbated the consumption of lithium resources.Therefore,researchers recognized the urgency of developing other energy storage technologies with high resource reserves（such as sodium-ion batteries（SIBs）and aluminum-ion batteries（AIBs））and finding high-performance cathode materials.Unlike the case in LIBs,the larger ionic radius of sodium ions and the stronger electrostatic effect of trivalent aluminum ions limited the use of normal cathode materials.Inorganic materials（such as transition metal oxides）are usually employed as cathode/anode materials for LIBs.However,the volume expansion and phase change of the inorganic materials caused by the intercalation/deintercalation behavior of larger sodium ions will further lead to poor cycle stability and lower reversible capacity;while the strong electrostatic effect of aluminum ions and the strong interaction with the electrolyte lead to poor AIBs’performance.Organic materials,as another type of promising electrode materials,show the advantages of low cost,rich resources,high capacity,and flexible structure.When used in SIBs and AIBs,they show better compatibility than inorganic materials.However,lower electronic conductivity and lower discharge platforms limit the performance of organic materials.In order to improve the performance of organic materials,nanosization of materials can shorten the diffusion paths of ionic and charge,thereby obtaining better battery performance.In this paper,organic cathode materials are prepared based on the size-controlled method,which are applied to SIBs and AIBs,respectively.1)One-step synthesis method of concentration control was used to prepare poly（pyrrole-squaraine）（PPS）micro/nanospheres with different particle sizes for use in SIBs.The sample with200 nm diameter showed the best performance;2)two different sizes of pyrene-4,5,9,10-tetraone（PTO）were obtained by antisolvent method for use in AIBs,and 300 m Ah g^-1 capacity was realized.Through batteries’performance analysis,we found that the smaller the size of the nanomaterial prepared through size control methods,the shorter the diffusion length,the better charge transfer and ion diffusion,thereby accelerating the electrochemical reaction kinetics and improving the batteries’performance.Among them,the aluminum ion battery shows a high battery capacity,and has excellent research and application prospects.The nanosization of small molecular materials is conducive to the release of the material’s full capacity,but it also brings more serious material dissolution,which affects the cycle stability.Furthermore,it is possible to obtain high-performance AIBs cathode materials by means of polymerization and size control.