In recent years, the concept of sustainable development has encouraged the development and application of green, natural, and recyclable energy storage devices. Herein, using Ni(NO 3 ) 2 0.6 H 2 O and Co(NO 3 ) 2 0.6 H 2 O as raw material and K 2 S 2 O 8 as a vulcanizing agent, NiCo 2 S 4 nanomaterials@C 3 N 4 (NCS@C 3 N 4 ) composite was prepared by a one-step solvothermal method, in which the introduction of C 3 N 4 significantly improves the dispersion of NCS , while the petal-like NCS also expands the layer spacing of C 3 N 4 , which effectively alleviates the structural instability and promotes the exposure of stable active sites during charge and discharge. Physical structure and electrochemical characterizations showed that the NCS were distributed on the surface of the C 3 N 4 nanosheets , which reduced the stacking of the nanosheets and accelerated the charge transfer during the charging and discharging process. The specific capacity ( C sp ) of the NCS@C 3 N 4 composite electrode was up to 890.4 C/g at a current density of 1 A/g. In addition, the supercapacitor consisting of NCS@C 3 N 4 composite electrode had good cycling stability and still displayed excellent capacitance retention after 3000 cycles. The NCS@C 3 N 4 composite greatly optimizes the stability and extends the operating life of supercapacitors, which has a broad application potential in the field of energy storage devices.
Jintang Zhou,Yijie Liu,Congyu Zhou,Weize Wang,Lvtong Duan,Yucheng Wang,Zhengjun Yao
The modern and complex environment requires microwave absorbing materials (MAMs) that can cope with environmental changes. In particular, the high humidity, high salt spray and high temperature of the marine environment conditions have been the toughest. Consequently, the development of integrated materials with both microwave absorption (MA) and corrosion resistance has emerged as a top priority. In this work, spherical NiCo 2 S 4 (NCS) particles with stable size were prepared by a simple solvothermal method. Furthermore, the self-polymerization of dopamine (PDA) on the surface of NCS was achieved by exploiting the film-forming ease of dopamine. A series of PDA-NCS particles with different interfaces were fabricated by tuning the ratio of NCS and dopamine. The integrated magneto-electric drive synergy enhances the impedance matching. Multiple heterogeneous interfaces enhance the depletion efficiency of electromagnetic waves (EMWs) within the material. The samples designed have achieved an effective absorption bandwidth (EAB) value of 6.26 GHz and a maximum reflection loss value of −22 dB at a low thickness of 1.7 mm. Meanwhile, due to the electrochemical protection reaction of anode of metal and the passivation effect of barrier by PDA. The prepared coatings maintained favorable corrosion resistance in 240 h of continuous salt spray environment. Moreover, after the 240 h salt spray experiment, the sample realized the EAB value of 4.77 GHz at a thickness of 1.7 mm. This work breaks new ground for the development of absorbing and anti-corrosion integrated materials.
Wenming Zhang,Jintao Chen,Yiqun Liu,Siming Liu,Xiaoting Li,Kun Yang,Ling Li
Although potassium ion batteries (KIBs) have been invested in development as an emerging low-cost, high-content energy storage system at present. However, the large ionic radius of K + -ion lead to poor rate performance and low cycle life. Therefore, it is extremely necessary to develop a new type of potassium storage material. Here, we report a novel three-dimensional (3D) structural self-supported anode composite material for KIBs, which consists of tapered rod-shaped nanomaterial NiCo 2 S 4 and nitrogen-doped hollow carbon nanofibers (NiCo 2 S 4 @N-HCNFs). Then, the composite material was obtained by high temperature carbonization and hydrothermal reaction process. The prepared electrode materials were used to assemble K half-cells for electrochemical performance measurement, achieved the capacity of 263.7 mAh g −1 after 200 cycles at a current density of 100 mA g −1 and an outstanding stability of retaining 134.3 mAh g −1 at 3200 mA g −1 after 600 cycles. It has superior performance and convenient synthesis process over other reported metal sulfides self-supported anode materials for KIBs so far. The novel structure not only shorten the ion transmission distance, but also increase the contact area with the electrolyte. It can improve electrochemical performance effectively.
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