Facile synthesis of accordion-like porous carbon from waste PET bottles-based MIL-53(Al)and its application for high-performance Zn-ion capacitor

It is of great scientific and economic value to recycle waste poly(ethylene terephthalate)(PET)into high-value PET-based metal organic frameworks(MOFs)and further convert it into porous carbon for green energy storage applications.In the present study,a facile and costeffective hydrothermal process was developed to direct recycle waste PET bottles into MIL-53(Al)with a 100% conversation,then the MOFderived porous carbon was assembled into electrodes for high-performance supercapacitors.The results indicated that the as-synthesized carbon exhibited high SSA of 1712 m^(2)g^(-1)and unique accordion-like structure with hierarchical porosity.Benefit to these advantageous characters,the assembled three-electrode supercapacitor displayed high specific capacitances of 391 F g^(-1)at the current density of 0.5 A g^(-1)and good rate capability of 73.6% capacitance retention at 20 A g^(-1)in 6 mol L^(-1)KOH electrolyte.Furthermore,the assembled zinc ion capacitor still revealed outstanding capacitance of 335 F g^(-1)at 0.1 A g^(-1),excellent cycling stability of 92.2% capacitance retention after 10000 cycles and ultra-high energy density of 150.3 Wh kg^(-1)at power density of 90 W kg^(-1)in 3 mol L^(-1)ZnSO_(4)electrolyte.It is believed that the current work provides a facile and effective strategy to recycle PET waste into high-valuable MOF,and further expands the applications of MOF-derived carbons for high-performance energy storage devices,so it is conducive to both pollution alleviation and sustainable economic development.

Recent advances of metal fluoride compounds cathode materials for lithium ion batteries:a review

As the most successful new energy storage device developed in recent decades,lithium-ion batteries(LIBs)are ubiquitous in the modern society.However,current commercial LIBs comprising mainly intercalated cathode materials are limited by the theoretical energy density which cannot meet the high storing energy demanded by renewable applications.Compared to intercalation-type cathode materials,low-cost conversion-type cathode materials with a high theoretical specific capacity are expected to boost the overall energy of LIBs.Among the different conversion cathode materials,metal fluorides have become a popular research subject for their environmental friendliness,low toxicity,wide voltage range,and high theoretical specific capacity.In this review,we compare the energy storage performance of intercalation and conversion cathode materials based on thermodynamic calculation and summarize the main challenges.The common conversion-type cathode materials are described and their respective reaction mechanisms are discussed.In particular,the structural flaws and corresponding solutions and strategies are described.Finally,we discussed the prospective of metal fluorides and other conversion cathode materials to guide further research in this important field.