Self-supported hierarchical porous Li_(4)Ti_(5)O_(12)/carbon arrays for boosted lithium ion storage

The development of fast rechargeable lithium ion batteries(LIBs)is highly dependent on the innovation of advanced high-power electrode materials.In this work,for the first time,we report a sacrificial NiO arrays template method for controllable synthesis of self-supported hierarchical porous Li_(4)Ti_(5)O_(12)/C(LTO/C)nanoflakes arrays,for use as fast rechargeable anodes for LIBs.The ultrathin(2-3 nm)carbon layer was uniformly coated on the LTO forming arrays architecture.The hierarchical porous LTO/C nanoflakes consisted of primary cross-linked nanoparticles of 50-100 nm and showed large porosity.Because of the enhanced electrical conductivity and accelerated ion transfer channels,the well-designed binderfree porous LTO/C nanoflakes arrays exhibited notable high-rate lithium ion storage performance with smaller polarization,better electrochemical reactivity,higher specific capacity(157 mAh g^(-1) at the current density of 20C)and improved long-term cycling life(96.2% after 6000 cycles at 20C),superior to the unmodified porous LTO arrays counterpart(126 mAh g^(-1) at 20C and 88.0%after 6000 cycles at 20C).Our work provides a new template for the construction of high-performance high-rate electrodes for electrochemical energy storage.

Atomic Layer Deposition-Assisted Construction of Binder-Free Ni@N-Doped Carbon Nanospheres Films as Advanced Host for Sulfur Cathode

Rational design of hybrid carbon host with high electrical conductivity and strong adsorption toward soluble lithium polysulfides is the main challenge for achieving high-performance lithium-sulfur batteries(LSBs).Herein,novel binder-free Ni@N-doped carbon nanospheres(N-CNSs)films as sulfur host are firstly synthesized via a facile combined hydrothermal-atomic layer deposition method.The cross-linked multilayer N-CNSs films can effectively enhance the electrical conductivity of electrode and provide physical blocking“dams”toward the soluble long-chain polysulfides.Moreover,the doped N heteroatoms and superficial NiO layer on Ni layer can work synergistically to suppress the shuttle of lithium polysulfides by effective chemical interaction/adsorption.In virtue of the unique composite architecture and reinforced dual physical and chemical adsorption to the soluble polysulfides,the obtained Ni@N-CNSs/S electrode is demonstrated with enhanced rate performance(816 mAh g?1 at 2 C)and excellent long cycling life(87%after 200 cycles at 0.1 C),much better than N-CNSs/S electrode and other carbon/S counterparts.Our proposed design strategy offers a promising prospect for construction of advanced sulfur cathodes for applications in LSBs and other energy storage systems.

Recent progress on MOF-derived carbon materials for energy storage

Metal-organic frameworks(MOFs)are of quite a significance in the field of inorganic-organic hybrid crystals.Especially,MOFs have attracted increasing attention in recent years due to their large specific surface area,desirable electrical conductivity,controllable porosity,tunable geometric structure,and excellent thermal/chemical stability.Some recent studies have shown that carbon materials prepared by MOFs as precursors can retain the privileged structure of MOFs,such as large specific surface area and porous structure and,in contrast,realize in situ doping with heteroatoms(eg,N,S,P,and B).Moreover,by selecting appropriate MOF precursors,the composition and morphology of the carbon products can be easily adjusted.These remarkable structural advantages enable the great potential of MOF-derived carbon as high-performance energy materials,which to date have been applied in the fields of energy storage and conversion systems.In this review,we summarize the latest advances in MOF-derived carbon materials for energy storage applications.We first introduce the compositions,structures,and synthesis methods of MOF-derived carbon materials,and then discuss their applications and potentials in energy storage systems,including rechargeable lithium/sodium-ion batteries,lithium-sulfur batteries,supercapacitors,and so forth,in detail.Finally,we put forward our own perspectives on the future development of MOF-derived carbon materials.

Assembling Co_9S_8 nanoflakes on Co_3O_4 nanowires as advanced core/shell electrocatalysts for oxygen evolution reaction

Rational design of advanced cost-effective electrocatalysts is vital for the development of water electrolysis. Herein, we report a novel binder-free efficient CoS@CoOcore/shell electrocatalysts for oxygen evolution reaction（OER） via a combined hydrothermal-sulfurization method. The sulfurized net-like CoSnanoflakes are strongly anchored on the CoOnanowire core forming self-supported binder-free core/shell electrocatalysts. Positive advantages including larger active surface area of CoSnanoflakes,and reinforced structural stability are achieved in the CoS@CoOcore/shell arrays. The OER performances of the CoS@CoOcore/shell arrays are thoroughly tested and enhanced electrocatalytic performance with lower over-potential(260 m V at 20 m A cm) and smaller Tafel slopes（56 mV dec-1） as well as long-term durability are demonstrated in alkaline medium. Our proposed core/shell smart design may provide a new way to construct other advanced binder-free electrocatalysts for applications in electrochemical catalysis.

Flower-like Fe-doped NiSe_(2)/C hybrid spheres fabricated by a glucose-intercalation strategy for enhanced sodium storage proper

Nickel diselenide(NiSe_(2)),which has a high theoretical capacity,has attracted considerable attention as a promis-ing anode material for sodium-ion batteries(SIBs).Nevertheless,the intrinsically low conductivity,large volume variation,and significant aggregation of NiSe_(2)during sodiation/desodiation remain significant obstacles to its application.Herein,we report flower-like Fe-doped NiSe_(2)/C hybrid spheres(denoted as Fe-NiSe_(2)/C)fabricated by a glucose intercalation strategy for efficient sodium storage.These Fe-NiSe_(2)/C hybrid spheres are composed of thin porous carbon nanosheets decorated with Fe-NiSe_(2)nanoparticles.In situ introduced carbon nanosheets derived from intercalated glucose accompanied by moderate Fe doping in NiSe2 nanoparticles can provide ac-celerated ion/electron transfer kinetics through fast ion channels in the flower-like architecture and intimately contacted interfaces between NiSe_(2)and carbon nanosheets as well as maintain structural integrity by alleviating volume variation.Consequently,the optimal anode of the Fe-NiSe_(2)/C hybrid spheres delivered a high discharge capacity of 415 mAh g^(-1)at 0.5 A g^(-1),outstanding rate capability(243 mAh g^(-1)at 5 A g^(-1)),and significantly enhanced cycling stability(388 mAh g^(-1)at 1 A g^(-1)over 200 cycles).This work offers an efficient and valu-able strategy for realizing tailored heteroatom doping in transition metal selenides,accompanied by an in situ combination of conductive carbonaceous networks for advanced alkali metal ion batteries.

Heterostructured NiS_(2)@SnS_(2) hollow spheres as superior high-rate and durable anodes for sodium-ion batteries

Tin-based sulfides have attracted increasing attention as anodes for sodium-ion batteries(SIBs) owing to their high theoretical capacity;however, the poor rate capability and inferior cycling stability caused by the low electrical conductivity, sluggish kinetics and drastic volume variations during cycling have greatly hampered their practical applications. Herein, heterostructured NiS_(2)@SnS_(2) hybrid spheres were delicately designed and constructed by anchoring interconnected SnS_(2) nanosheets on metalorganic frameworks(MOFs)-derived Ni S_(2) hollow spheres coupled with N-doped carbon skeleton through facile solvothermal and sulfurization/carbonization processes. The unique hollow heterostructure with highly conductive carbon matrix can effectively facilitate the charge transfer kinetics and ensure the desired buffer space while endowing more active sites and enhanced structural integrity, as demonstrated by the experimental and density functional theory(DFT) results. Benefitting from these merits, the NiS_(2)@SnS_(2) hybrid composite displays a high reversible capacity of 820 m Ah g^(-1) after 250 cycles at 1 A g^(-1), and retains a value of 673 m Ah g^(-1)after 1,300 cycles at 5 A g^(-1), manifesting the excellent high-rate and durable sodium storage behaviors when applied in SIBs. This study shall shed more light on the fabricating and interface engineering of other transition metal-based composite anodes for high-performance SIBs.

Binder-free carbon fiber/TiNb2O7 composite electrode as superior high-rate anode for lithium ions batteries

Construction of advanced high-rate anodes is critical for the development of high-power lithium ion batteries （LIBs）. In this work, we report a binder-free carbon fiber/CF）]titanium niobium oxide （TiNb2O7 （TNO）） composite electrode via a simple solvothermal method combined with heat treatment. Continuous TNO film consisting of cross-linked TNO nanoparticles of 30-50 nm is strongly anchored on the carbon fiber forming integrated CF/TNO composite electrode. Owing to the intimate three- dimensional structure, the as-prepared CF]TNO electrode presents exceptional high-rate performance （245 mAh/g at 1 C, and 138 mAh/g at 80 C） and enhanced cyclability with a capacity of 150 mAh]g at the current density of 10 C after 1000 cycles. Our results demonstrate the CF/TNO electrode as efficient anode for application in high-power lithium ion batteries.

Co-construction of advanced sulfur host by implanting titanium carbide into Aspergillus niger spore carbon

It is of great importance to directionally construct advanced carbon host to achieve high-performance carbon/sulfur cathodes for lithium sulfur batteries(LSBs).Herein,we report a unique hollow pumpkinlike carbon with notable rich-wrinkle microstructure and intrinsically dual doping with N&P elements via a facile annealing process of Aspergillus niger spore.Furthermore,highly conductive polar absorbents,Ti C nanoparticles,are in situ implanted into the above Aspergillus niger spore carbon(ANSC)by carbothermal reaction,accordingly forming high-performance ANSC/TiC composite host for sulfur.Impressively,TiC nanoparticles play dual roles of not only pore formation in ANSC matrix but also enhancement of chemical absorption with polysulfides.With the positive synergistic effect between N&P co-doped ANSC matrix and Ti C polar absorbent,the designed ANSC/Ti C-S cathodes show unique advantages including larger accommodation space for sulfur,higher surface area,enhanced conductivity and better chemical absorption with soluble polysulfide intermediates.Consequently,the ANSC/Ti C-S cathodes are endowed with good rate performance(496 mAh/g at 0.5 C)and enhanced long-term cycling stability(736 mAh/g with a capacity retention of 78.8%at 0.1 C after 100 cycles).Our research opens a new door to controllably design advanced composite cathodes from microorganisms for application in lithium sulfur batteries.