Cathode materials with high capacity and cyclic durability are urgently needed for capacitive deionization . Na 3 V 2 (PO 4 ) 3 is an emerging pseudocapacitive candidate for this process on account of its high capacity and Na + reversible insertion, while it suffers from the intrinsic low electrical conductivity and small electrolyte-accessible surface area. Herein, a sea urchin-like Na 3 V 2 (PO 4 ) 3 @carbon (NVP@C) compound material was synthesized from MXene-V 2 C via hydrothermal method followed by annealing treatment, and then assembled as capacitive deionization (CDI) electrode material . Benefiting from three-dimensional sea urchin-like structure, where the nanoneedles of NVP@C serve as fast transport channel for Na + , NVP@C performed high specific capacity (437 F g −1 at 5 mV s −1 ) and fast ionic diffusion kinetics. Moreover, the NVP@C showed attractive desalination performance as cathode material for CDI, achieving a remarkable adsorption capacity of 74.0 mg g −1 in a NaCl salt solution (1000 mg L −1 ) and long life cycle stability. The present work provides a novel perspective to construct practical redox-active and stable CDI electrode with 3D structure from MXene for highly capacitive and durable desalination application .
Tan Dang,Lei Wang,Donghai Wei,Guiqing Zhang,Qinggang Li,Xiaojia Zhang,Zuoying Cao,Guanhua Zhang,Huigao Duan
Low-cost and resourceful transition metal phosphides (TMPs), as a new kind of pseudocapacitive materials, have received considerable interest for electrochemical energy storage/conversion. Combination of TMPs and carbon nanostructures is supposed to greatly improve the charge storage capability due to the synergistic effect. In this work, nickel cobalt phosphides nanosheets supported by P doped C spheres (P-CSs@Ni-Co-P NSs) composites with different Ni/Co molar ratios (1:0, 1:1, 1:2, 1:4 and 0:1) were prepared by in-situ bifunctional phosphorization of the as-synthesized CSs@Ni-Co-OH NSs precursor. The optimized 3D networked mesoporous P-CSs@Ni 1 -Co 2 -P NSs electrode exhibits a remarkable specific capacitance of 1040.3 F g −1 at 1 A g −1 and excellent rate capability with a capacitance retention of 49.2% even at 30 A g −1 , which are much higher than those of A-CSs@Ni 1 -Co 2 -O NSs (870.5 F g −1 at 1 A g −1 , 37.4% at 30 A g −1 ) and Ni 1 -Co 2 -P NSs (500.5 F g −1 at 1 A g −1 , 40.0% at 30 A g −1 ). The improved supercapacitive performances are attributed to the 3D mesoporous nanosheets network and bifunctional phosphorization treatment which lead to enhancement of conductivity. Meanwhile, Ni-Co bimetallic phosphide with abundant oxidation states facilitates redox charge transfer efficiently. Furthermore, P-CSs@Ni 1 -Co 2 -P NSs assembled asymmetric supercapacitors (ASC) achieve outstanding cycling stability with no decay of capacitance after 20000 cycles. Additionally, the charge storage kinetic of the device is further investigated, indicating that fast surface-control capacitive behavior is dominant at high current densities.
危险品化学品经营许可证（带存储）