Organic Monoacid-calix[3]quinone Cathode For Lithium/Sodium-ion Batteries

With the continuous progress of society and the urgent demand for clean energy,rechargeable metal-ion batteries such as lithium-ion batteries（LIBs）and sodium-ion batteries（SIBs）,which have long lifespan,high energy/power density and high safety,have attracted widespread attention.Cathode materials are a shortcoming of batteries.Inorganic cathode materials are difficult to break through the defect of low specific capacity,which limit the energy density and life of batteries to a large extent.While organic electrode materials have various specific structures and are environmentally friendly,among which the organic conjugated carbonyl compounds have the advantages of high theoretical specific capacity,fast electrochemical reaction speed and free from the restriction of reaction systems,and can be used in various metal-ion batteries for energy storage simultaneously.While their easy solubility in organic electrolytes causing battery capacities attenuation rapidly.（1）In this paper,the p-t Bu-calix[4]arene-monoacid-trisquinone(C3Q,C₃₄H₂₈O₉)is designed based on structural modification of calix[4]quinone（C4Q,four p-benzoquinones interlinked by methylene）and synthesized by a series of reactions including ring-forming,substitution,hydrolysis and oxidation,then it is adopted in rechargeable LIBs and SIBs as cathode material to compare the cycle ability with the C4Q cathode.The capacities of C4Q LIBs and SIBs decay rapidly at a current density of 0.2 C,and both of them almost decay completely after 50 cycles.By contrast,the electrochemical performance of C3Q cathode has been significantly improved.（2）For the LIBs,six carbonyl groups and one carboxyl group in C3Q can provide seven lithium-ion intercalation sites in the discharge process for the first cycle,with an initial capacity of 315 m Ah g^-1,the second cycle starts with the insertion/extraction of lithium-ions on six carbonyl groups,with a capacity of 273 m Ah g^-1.The capacity retention rate remains 54.2%after 200 cycles at 0.2 C,and the capacity reaches 122 m Ah g^-1 at 1 C in the rate test.（3）For the SIBs,the redox mechanism of C3Q is the similar as that of C3Q in LIBs,which is the reversible insertion/extraction of sodium-ions.The initial and second discharge capacities of the battery are 317 m Ah g^-1 and 266 m Ah g^-1 at a 0.2 C current density,respectively,and it is still above 100 m Ah g^-1 after 200 cycles.In the rate test,the capacity is 94 m Ah g^-1 at 1 C,and quickly rises to 158 m Ah g^-1 when the current density is reduced to 0.1 C.