The Electrochemical Performance Of Organic Electrode Materials In Potassium-Ion Batteries

As an emerging electrochemical energy storage system,potassium-ion batteries?KIBs?have attracted increasing attention.Organic compounds with many advantages,including potential low-cost,structure diversity,environmental friendliness and light weight,could be one kind of the most potential electrode materials for KIBs.The dissolution of organic materials in organic electrolyte causes rapid capacity decay,which would be a great obstacle to the development and application of organic electrode materials in rechargeable batteries,including KIBs.We studied the electrochemical performance of anthraquinone-1,5-disulfonic acid disodium salt?AQDS?and 2,6-naphthalenedicarboxylic acid dipotassium salt?2,6-Naph?COOK?₂?.The results provide new ideas for the development of organic electrode materials in KIBs.The research work mainly includes the following aspects:?1?The effects of polar-SO₃Na substituents on the solubility and electrochemical performance were studied with anthraquinone?AQ?and AQDS as the cathode materials for KIBs.The potassium storage mechanism in AQDS was studied using XRD,SEM and FTIR characterization.The results show that compared with AQ the dissolution of AQDS in organic electrolytes is considerably suppressed by the incorporation of the sodium sulfonate substituent groups.And significantly enhanced electrochemical performance was demonstrated with a good cycling stability remaining a capacity of 78 mA h g^-1 after 100 cycles.The FTIR and ex-XRD results reveal that the carbonyl groups of the AQDS molecules function only as active sites to store K⁺ions and a reversible structural change during the charge/discharge processes.The sodium sulfonate substituents are electrochemically stable to K⁺ions and function to reduce the solubility of the AQDS molecules.?2?The electrochemical performance of 2,6-Naph?COOK?₂ as a KIB anode was investigated.The results showed that 2,6-Naph?COOK?₂ electrode using CMC binder delivered a good stability with a specific capacity retention of 124 mA h g^-1 after 200cycles at a current density of 20 mA g^-1,demonstrating good cycling performance.And a high rate capability remaining 64 mA h g^-1 was also obtained even at a high current density of 1000 mA g^-1,showing good rate performance.It can be concluded that 2,6-Naph?COOK?₂ can be a promising anode material for KIBs with excellent electrochemical performance.