Engineering CoMoO_(4) in reduced graphene oxide as superior cathode hosts for advanced room-temperature sodium-sulfur batteries

Promising room-temperature sodium-sulfur(RT Na-S)battery systems rely on purposely designed highperforming and low-cost electrode materials.Nevertheless,there are the challenges of irreversible dissolution and slow redox kinetics of NaPSs in the complete discharge of sulfur capacity.Herein,engineered CoMoO_(4)in reduced graphene oxide(CoMoO_(4)@rGO)is reported as a class of superior cathode hosts for RT Na-S batteries.The CoMoO_(4)@rGO matrix is designed to facilitate the reversible sodiation and desodiation of sulfur,considering the strong chemisorption between sulfur(and short-chain sodium sulfides)and CoMoO_(4),which alleviates the shuttle effect of sodium sulfides and accelerates the electrochemical reaction rate at RT.The obtained S/CoMoO_(4)@rGO cathode with~52%S loading exhibits a high capacity of520.1 mA h g^(-1)after 100 cycles at 0.1 A g^(-1).Moreover,an enhanced long-term performance at high current densities(212.2 mA h g^(-1)at 4 A g^(-1)over 1000 cycles)with high Coulombic efficiency(~100%)is also achieved.This work demonstrates a novel multifunctional additive for RT Na-S battery cathodes,which is expected to promote the long-waited development towards practical applications of RT Na-S batteries.

Homologous Strategy to Construct High‑Performance Coupling Electrodes for Advanced Potassium‑Ion Hybrid Capacitors

Potassium-ion hybrid capacitors(PIHCs)have been considered as promising potentials in mid-to large-scale storage system applications owing to their high energy and power density.However,the process involving the intercalation of K+into the carbonaceous anode is a sluggish reaction,while the adsorption of anions onto the cathode surface is relatively faster,resulting in an inability to exploit the advantage of high energy.To achieve a high-performance PIHC,it is critical to promote the K^+insertion/desertion in anodic materials and design suitable cathodic materials matching the anodes.In this study,we propose a facile“homologous strategy”to construct suitable anode and cathode for high-performance PIHCs,that is,unique multichannel carbon fiber(MCCF)-based anode and cathode materials are firstly prepared by electrospinning,and then followed by sulfur doping and KOH activation treatment,respectively.Owing to a multichannel structure with a large interlayer spacing for introducing S in the sulfur-doped multichannel carbon fiber(S-MCCF)composite,it presents high capacity,super rate capability,and long cycle stability as an anode in potassium-ion cells.The cathode composite of activated multichannel carbon fiber(aMCCF)has a considerably high specific surface area of 1445 m^2 g^−1 and exhibits outstanding capacitive performance.In particular,benefiting from advantages of the fabricated S-MCCF anode and aMCCF cathode by homologous strategy,PIHCs assembled with the unique MCCF-based anode and cathode show outstanding electrochemical performance,which can deliver high energy and power densities(100 Wh kg^−1 at 200 W kg^−1,and 58.3 Wh kg^−1 at 10,000 W kg^−1)and simultaneously exhibit superior cycling stability(90%capacity retention over 7000 cycles at 1.0 A g^−1).The excellent electrochemical performance of the MCCF-based composites for PIHC electrodes combined with their simple construction renders such materials attractive for further in-depth investigations of alkali-ion battery and capacitor applications.

Killing two birds with one stone:Constructing tri-elements doped and hollow-structured carbon sphere by a single template for advanced potassium-ion hybrid capacitors

Integrating the merits of long lifespan and excellent energy as well as power densities,potassium-ion hybrid capacitors(PIHCs)exhibit great prospects for future energy storage devices.To boost comprehensive performance of PIHCs,heteroatom-doping and morphology-tuning as two comprehensive strategies have been devoted to designing uniquely structural carbon-based materials with favorable advantages.An ideal strategy for simultaneous atomic doping and structural regulation is expected to be developed.Herein,we propose a novel"Killing Two Birds with One Stone"strategy to prepare a tri-elements doped hollow carbon sphere(TED-HCS)as PIHCs anodes,that is,a single template of spherical CoP particles is rationally adopted,which not only provides both a P source for heteroatom-doping but also acts as a selfsacrificial template for hollow-structure engineering.The multifunctional TED-HCS presents a high capacity of 473.0 mAh g^(-1) and excellent rate performance of 212.5 mAh g^(-1) at 5.0 A g^(-1).Remarkably,the as-assembled PIHCs show outstanding energy/power density(40.4 Wh kg^(-1)/10500 W kg^(-1))and remain high-capacity retention of 89.15%even cycling 12,000 times.The"Killing Two Birds with One Stone"strategy offers new insight into the search for the preparation of carbon-based materials with multi-elements doping and specific morphology structure.

高电压锂离子正极材料LiNi_(0.5)Mn_(1.5)O_(4)高温特性

随着新能源电动汽车和大容量储能的快速发展,亟需开发高能量密度、高功率密度的锂离子电池。镍锰酸锂(LiNi_(0.5)Mn_(1.5)O_(4))由于具有高电压平台(4.7V)、较高的能量密度和功率密度、资源丰富、成本低等优点,被认为是最具潜力的锂离子电池正极材料之一。然而,在高温条件下,LiNi_(0.5)Mn_(1.5)O_(4)会与电解液发生严重的界面副反应,导致循环性能变差,这严重制约了其商业化进程。因此,改善LiNi_(0.5)Mn_(1.5)O_(4)的高温特性成为锂离子电池领域的研究热点之一。本文对近期LiNi_(0.5)Mn_(1.5)O_(4)材料相关研究的主要成果进行综述,以LiNi_(0.5)Mn_(1.5)O_(4)的基本特性和现存挑战入手,着重关注离子掺杂、表面包覆和表面掺杂等策略提升材料的高温性能,并为后续研究提出建议和展望。