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Flexible electrodes based on conversion-type materials have potential applications in low-cost and high-performance flexible sodium-ion batteries (FSIBs), owing to their high theoretical capacity and appropriate sodiation potential. However, they suffer from flexible electrodes with poor mechanical properties and sluggish reaction kinetics. In this study, freestanding CoS 2 nanoparticles coupled with graphene oxides and carbon nanotubes (CoS 2 /GO/CNTs) flexible films with robust and interconnected architectures were successfully synthesized. CoS 2 /GO/CNTs flexible film displays high electronic conductivity and superior mechanical properties (average tensile strength of 21.27 MPa and average toughness of 393.18 KJ m -3 ) owing to the defect bridge for electron transfer and the formation of the π-π interactions between CNTs and GO. In addition, the close contact between the CoS 2 nanoparticles and carbon networks enabled by the Co-N chemical bond prevents the self-aggregation of the CoS 2 nanoparticles. As a result, the CoS 2 /GO/CNTs flexible film delivered superior rate capability (213.5 mAh g -1 at 6 A g -1 , better than most reported flexible anode) and long-term cycling stability. Moreover, the conversion reaction that occurred in the CoS 2 /GO/CNTs flexible film exhibited pseudocapacitive behavior. This study provides meaningful insights into the development of flexible electrodes with superior mechanical properties and electrochemical performance for energy storage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

The olivine lithium iron phosphate (LFP) cathode has gained significant utilization in commercial lithium-ion batteries (LIBs) with graphite anodes. However, the actual capacity and rate performance of LFP still require further enhancement when combined with high-capacity anodes, such as silicon (Si) anodes, to achieve high-energy LIBs. In this study, we introduce a gelatin-derived carbon network into a nanosized LFP cathode without the need for additional binding and conductive agents, employing a simple and cost-effective method. The resulting cathode exhibits an extremely high LFP content (∼92.3 wt%), enabling it to show a high real capacity of 159.7 mAh/g at 0.2 C in half cells. Additionally, the interconnected carbon network effectively facilitates electron and Li + transport, providing rapid pathways within the LFP nanoparticles. Consequently, the cathode exhibits superior rate capability (107.3 mAh/g at 10 C) and good cycling performance (with a capacity retention of ∼ 80 % after 500 cycles). To further assess its practical viability, the LFP cathode is assembled into a full cell utilizing a Si-based anode with a N/P ratio of 1.1. The resulting full cell delivers a significantly high energy density of 419.7 Wh kg -1 , coupled with prolonged cycle life, highlighting its promising prospects for practical applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Cobalt selenide, as a star material in battery industry, has attracted much attention. However, when it is applied solely in sodium ion batteries, it will cause large volume expansion and material agglomeration, which will seriously affect the overall performance of batteries. In this work, we use ice bath impregnation to combine CoSe 2 nanoparticles with porous nitrogen-doped carbon networks (NC) as advanced anodes for ultra-long cycle life sodium ion batteries (SIBs). CoSe 2 nanoparticles are evenly attached to NC with strong interfacial contacts in CoSe 2 @NC. The strong contact of CoSe 2 on the porous carbon network, along with the carbon network's unique network cross-linking structure, results in rapid electron transfer and Na ion diffusion kinetics of CoSe 2 @NC, resulting in superior electrochemical performance. Besides, we have synthesized CoSe 2 @NC with different loading by changing Co 2+ concentration. The results show that CoSe 2 @NC anode thus provides a high reversible capacity of 406 mAh/g. In addition, at high current 5 A/g, it can keep a reversible capacity of 300 mAh/g after 4500 cycles with an average capacity loss of less than 0.01 % per cycle. The excellent anchoring structure enables it to form stable solid electrolyte film (SEI) and reduce the amount of dead sodium in the first charge-discharge process, showing high Initial Coulombic Efficiency (ICE) (89.2 %). Finally, CoSe 2 @NC and Na 3 V 2 (PO 4 ) 3 (NVP) are assembled into a full cell and the results shows an ultra-long cycle stability at 0.1 A/g. This strategy will facilitate the application of transition metal selenides in next-generation energy storage systems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Supercapacitors are high power energy storage devices, however, their application are remain limited by the low energy density. Developing high capacity electrode materials and constructing devices with high operating voltage are effective ways to solve this problem. Herein, performance of polyaniline (PANI) electrode materials is dramatically enhanced by engineering robust PANI/carbon interfaces, through assembling PANI nanorod array on rose petals derived carbon network (RPDCN). The structure of the PANI is optimized by adjusting the concentration of the aniline precursor. The unique structure enables the prepared PANI/RPDCN composite show a high capacitance of 636 F g -1 at 0.5 A g -1 , based on the total weight of PANI and RPDCN substrate. The robust interface effectively prolonged the composite electrode stably cycled for over 2000 cycles at 2 A g -1 with a capacity retention of 89%. When coupled with a hexagonal tungsten oxide (h-WO 3 ) anode, a high-power asymmetric proton supercapacitor with high energy densities (29.0 Wh kg -1 /0.61 kW kg -1 and 21.4 Wh kg -1 /19.51 kW kg -1 ) was assembled. This work provides an effective and eco-friendly route toward superior PANI electrodes and proposes a promising high-power energy storage system using proton as working ion., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Sufficient and well-distributed active sites and highly conductive carbon matrix are two important factors to achieve highly efficient electrocatalysts. In this study, we report an adjusted metal-organic frameworks (MOF)-based route for the preparation of nitrogen-doped Fe/Co bimetallic electrocatalysts. With suitable Fe/Co molar ratio (Fe/Co = 1/4.15), Co nanoparticles (NPs) with mild oxidation state and Co 3 Fe 7 alloys wrapped with thin graphene layers are embedded in an integrated and continuous carbon network. The corresponding FC@NCs-4.15 catalyst exhibits excellent oxygen reduction reaction (ORR) activity (onset potential (E onset ) of 0.94 V and half-wave potential (E 1/2 ) of 0.84 V vs RHE) in alkaline medium, close to commercial Pt/C and superior to the other two FC@NCs. The desirable ORR performance results from the uniform distribution Co 3 Fe 7 active sites, electron density modification from Co NPs to surrounding carbon layers, hierarchical pore structure with large surface area, low carbon content, high pyridinic and graphitic N components. The FC@NCs-4.15 also displays satisfactory methanol crossover tolerance and durability., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Cost-effective electrocatalysts with excellent oxygen reduction reaction (ORR) activity are requisite for the commercial application fuel cells and zinc-air batteries. Herein, we prepare a series of carbon-based non-precious metal catalysts by simply carbonizing the mixture of FeCo-ZIF, melamine and soya-bean oil. The microstructure and electrochemical activity of the prepared catalysts highly depend on the adding amount of FeCo-ZIF. With proper addition, the FeCo-ZIF are transformed into Co 5.47 N and Co 0.72 Fe 0.28 alloy nanoparticles, which are embedded in the in situ formed carbon network consisted of nitrogen-doped graphene-like carbon nanosheets and interwoven carbon nanotubes. The resulted catalyst (FeCo@NCs-0.15) with considerable specific surface area and high pore volume demonstrates a superior ORR catalytic activity than commercial Pt/C with a half-wave potential (E 1/2 ) of 0.83 V (vs. RHE), onset potential (E onset ) of 0.97 V (vs. RHE) and 4-electron dominated reaction path. The durability and methanol resistance are also better than that of commercial Pt/C in alkaline solution. This study provides an inexpensive, facile and scalable strategy to simultaneously realize non-precious metal-based active sites, nitrogen-doping, porosity and highly conductive carbon matrix in one electrocatalyst by one step., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)