Recent advances in energy storage mechanism of aqueous zinc-ion batteries

Aqueous rechargeable zinc-ion batteries(ZIBs)have recently attracted increasing research interest due to their unparalleled safety,fantastic cost competitiveness and promising capacity advantages compared with the commercial lithium ion batteries.However,the disputed energy storage mechanism has been a confusing issue restraining the development of ZIBs.Although a lot of efforts have been dedicated to the exploration in battery chemistry,a comprehensive review that focuses on summarizing the energy storage mechanisms of ZIBs is needed.Herein,the energy storage mechanisms of aqueous rechargeable ZIBs are systematically reviewed in detail and summarized as four types,which are traditional Zn^(2+)insertion chemistry,dual ions co-insertion,chemical conversion reaction and coordination reaction of Zn^(2+)with organic cathodes.Furthermore,the promising exploration directions and rational prospects are also proposed in this review.

Strongly Coupled 2D Transition Metal Chalcogenide-MXene-Carbonaceous Nanoribbon Heterostructures with Ultrafast Ion Transport for Boosting Sodium/Potassium Ions Storage

Combining with the advantages of two-dimensional(2D)nanomaterials,MXenes have shown great potential in next generation rechargeable batteries.Similar with other 2D materials,MXenes generally suffer severe self-agglomeration,low capacity,and unsatisfied durability,particularly for larger sodium/potassium ions,compromising their practical values.In this work,a novel ternary heterostructure self-assembled from transition metal selenides(MSe,M=Cu,Ni,and Co),MXene nanosheets and N-rich carbonaceous nanoribbons(CNRibs)with ultrafast ion transport properties is designed for sluggish sodium-ion(SIB)and potassium-ion(PIB)batteries.Benefiting from the diverse chemical characteristics,the positively charged MSe anchored onto the electronegative hydroxy(-OH)functionalized MXene surfaces through electrostatic adsorption,while the fungal-derived CNRibs bonded with the other side of MXene through amino bridging and hydrogen bonds.This unique MXene-based heterostructure prevents the restacking of 2D materials,increases the intrinsic conductivity,and most importantly,provides ultrafast interfacial ion transport pathways and extra surficial and interfacial storage sites,and thus,boosts the high-rate storage performances in SIB and PIB applications.Both the quantitatively kinetic analysis and the density functional theory(DFT)calculations revealed that the interfacial ion transport is several orders higher than that of the pristine MXenes,which delivered much enhanced Na+(536.3 mAh g^(−1)@0.1 A g^(−1))and K^(+)(305.6 mAh g^(−1)@1.0 A g^(−1))storage capabilities and excel-lent long-term cycling stability.Therefore,this work provides new insights into 2D materials engineering and low-cost,but kinetically sluggish post-Li batteries.

Nitrogen/sulphur dual-doped hierarchical carbonaceous fibers boosting potassium-ion storage

The carbon materials as anode electrodes have been widely studied for potassium ion batteries(PIBs).However,the large size of potassium ions prevents their intercalation/deintercalation,resulting in poor storage behaviors.Herein,a novel design of N/S codoped hierarchical carbonaceous fibers(NSHCF)formed from nanosheets self-assembled by catalyzing Aspergillus niger with Sn is reported.The asprepared NSHCF at 600℃(NSHCF-600)exhibits a high reversible capacity of 345.4 m Ah g^(-1) at 0.1 A g^(-1) after 100 cycles and an excellent rate performance of 124.5 m Ah g^(-1) at 2 A g^(-1).The excellent potassium storage performance can be ascribed to the N/S dual-doping,which enlarges interlayer spacing(0.404 nm)and introduces more defects.The larger interlayer spacing and higher pyridinic N active sites can promote K ions diffusion and storage.In addition,the ex situ transmission electron microscopy reveals the high reversibility of potassiation/depotassiation process and structural stability.

High-performance flexible sensing devices based on polyaniline/MXene nanocomposites

Highly active two-dimensional(2D)nanocomposites,integrating the unique merits of individual components and synergistic effects of composites,are greatly desired for flexible sensing device applications.Although 2D transition metal carbides and nitrides(MXenes)combined with their high metallic conductivity and versatile surface chemistry have shown its huge potential for sensing reactions,it still remains a major challenge to construct functional materials with intriguing sensing performance at room temperature(RT).Herein,we used an integration of density functional theory(DFT)simulations and bulk electrosensitive measurements to show high electrocatalytic sensitivity of polyaniline/MXene(PANI/Ti3C2Tx)nanocomposites.Thanks to the synergistic properties of nanocomposites and high catalytic/absorption capacity of Ti3C2Tx MXene,PANI nanoparticles are rationally decorated on Ti3C2Tx nanosheet surface via in situ polymerization by low temperature approach to induce remarkable detection sensitivity,rapid response/recovery rate,and mechanical stability at RT.This study offers a versatile platform to use MXenes to fabricate 2D nanocomposites materials for high-performance flexible gas sensors.

Biocompatible and Biodegradable Functional Polysaccharides for Flexible Humidity Sensors

Using wearable devices to monitor respiration rate is essential for reducing the risk of death or permanent injury in patients.Improving the performance and safety of these devices and reducing their environmental footprint could advance the currently used health monitoring technologies.Here,we report high-performance,flexible bioprotonic devices made entirely of biodegradable biomaterials.This smart sensor satisfies all the requirements for monitoring human breathing states,including noncontact characteristic and the ability to discriminate humidity stimuli with ultrahigh sensitivity,rapid response time,and excellent cycling stability.In addition,the device can completely decompose after its service life,which reduces the risk to the human body.The cytotoxicity test demonstrates that the device shows good biocompatibility based on the viability of human skin fibroblast-HSAS1 cells and human umbilical vein endothelial(HUVECs),illustrating the safety of the sensor upon integration with the human skin.