Lithiation-induced controllable vacancy engineering for developing highly active Ni_(3)Se_(2) as a high-rate and large-capacity battery-type cathode in hybrid supercapacitors

The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.

3D hierarchical oxygen-deficient AlCoNi-(oxy)hydroxides/N-doped carbon hybrids enable efficient battery-type asymmetric supercapacitor

Polynary transition-metal layered hydroxides are promising energy materials owing to their unique architecture,impressive theoretical capacities,and adjustable compositions.Regulating the dimensional morphology and active sites/redox states are the keys to electrochemical performance enhancement.Distinguish from the reported mono-metal or binary-metal configurations,a new ternary-metal AlCoNi-LTH is coanchored onto a highly graphitized porous N-doped carbon matrix to develop superior 3D hierarchical microporous functional energy hybrids AlCoNi-LTHs/NAC.The constructed hybrids possess superior structural durability,good electrical conductivity,and rich active sites due to the strong interfacial conjunction and favorable synergistic effect between the doped porous carbon and AlCoNi nanosheets.Consequently,the AlCoNi-LTHs/NAC hybrids demonstrate high conductivity,reasonable specific surface area,and superior specific capacitance,and the assembled hybrid battery-type supercapacitor reveals an ideal energy density of 72.6 Wh kg^(-1)at a power density of 625 W kg^(-1),which is superior to the reported devices.This strategy opens a platform to rationally design polynary transition-metal layered hydroxides and their hybrids for efficient supercapacitors.

Mixed-phase composites derived from cobalt terephthalate as efficient battery-type electrodes for high-performance supercapattery

Interfacial engineering of two-dimensional(2D)monometallic phosphides enables remarkable structural and electrochemical properties in energy storage devices.Herein,2D nanosheets(NSs)of FeP_(2)/Co_(2) P were grown on Ni-foam(FCP)using a solution-based and phosphorization approach to be used as freestanding for high-performance energy storage devices.An effective phosphorization strategy is successfully de-veloped to improve the overall crystalline phase,tailor the morphology,and boost the electrochemical performances of electrodes.The FCP NSs electrode exhibits a battery-type redox behavior with a maxi-mum high areal capacity of 1.96 C cm^(-2) at 4 mA cm^(-2) in 6 M KOH aqueous electrolyte compared to the other counterparts.The superior electrochemical performance was achieved by increasing the electroac-tive sites and high conductivity via surface tailoring and fast redox reactions.Moreover,a supercapattery was assembled utilizing FCP and activated carbon(AC)electrodes and it revealed maximum specific en-ergy(E_(s))and specific power(P_(s))of 41.2 Wh kg^(-1) and 7578 W kg^(-1) with good cycling stability of 91%after 10,000 cycles at 5 A g^(-1).Eventually,the supercapattery has been explored in practical applications by lighting up light-emitting diodes(LEDs),representing the real-time performance of superior energy storage devices.

Porous CuCo_(2)O_(4) microtubes as a promising battery-type electrode material for high-performance hybrid supercapacitors

Hollow nanostructures of transition metal oxides(TMOs)with hollow interior,low density,large surface area and surface permeability have drawn significant interest as electrode materials for supercapacitors.However,it is still challenging to controllably prepare hollow nanostructures by a facile method.Herein,we report for the first time that CuCo_(2)O_(4 )microrod precursor obtained from a solvothermal method in ethanol media can be converted into porous CuCo_(2)O_(4 )microtubes(CuCo_(2)O_(4 )MTs)in the post annealing treatment.The results of electrochemical tests demonstrate that these MTs are categorized as the typical battery-grade electrode materials.They can deliver a high capacity up to 393.66 C g^(-1) at ^(-1) A g^(-1) and still hold 305.99 C g^(-1) at 10 A g^(-1).Additionally,an assembled hybrid supercapacitor(CuCo_(2)O_(4 )MTs//AC HSC)exhibits 78.23 F g^(-1),good cycling durability and high energy density(32.49 W h kg^(-1) at 912.10 W kg^(-1)).The present synthetic methodology may be further applicable to the preparation of other hollow structural TMOs with applications in high-performance energy storage and conversion devices.

A New Free-Standing Aqueous Zinc-Ion Capacitor Based on MnO2–CNTs Cathode and MXene Anode

Restricted by their energy storage mechanism,current energy storage devices have certain drawbacks,such as low power density for batteries and low energy density for supercapacitors.Fortunately,the nearest ion capacitors,such as lithium-ion and sodium-ion capacitors containing battery-type and capacitor-type electrodes,may allow achieving both high energy and power densities.For the inspiration,a new zinc-ion capacitor(ZIC)has been designed and realized by assembling the free-standing manganese dioxide-carbon nanotubes(MnO2-CNTs)battery-type cathode and MXene(Ti3C2Tx)capacitortype anode in an aqueous electrolyte.The ZIC can avoid the insecurity issues that frequently occurred in lithium-ion and sodium-ion capacitors in organic electrolytes.As expected,the ZIC in an aqueous liquid electrolyte exhibits excellent electrochemical performance(based on the total weight of cathode and anode),such as a high specific capacitance of 115.1 F g?1(1 mV s?1),high energy density of 98.6 Wh kg?1(77.5 W kg?1),high power density of 2480.6 W kg?1(29.7 Wh kg?1),and high capacitance retention of^83.6%of its initial capacitance(15,000 cycles).Even in an aqueous gel electrolyte,the ZIC also exhibits excellent performance.This work provides an essential strategy for designing next-generation high-performance energy storage devices.

Recent advances in zinc-ion hybrid energy storage: Coloring high-power capacitors with battery-level energy

Zinc-ion hybrid capacitors(ZICs) are considered as newly-emerging and competitive candidates for energy storage devices due to the integration of characteristic capacitor-level power and complementary battery-level energy. The practical application of rising ZICs still faces the specific capacity and dynamics mismatch between the two electrodes with different energy storage mechanisms, which cannot meet the ever-growing indicator demand for portable electronic displays and public traffic facilities. Focusing on these unresolved issues, this mini-review presents recent advances in ZICs referring to the hybrid energy storage mechanism, design strategies of both capacitor-type and battery-type electrode materials, and electrolyte research toward advanced performances(e.g., high operational potential, wide adaptive temperature). Finally, current challenges and future outlook have been proposed to guide further exploration of next-generation ZICs with a combination of high-power delivery, high-energy output and high-quality service durability.

具有O–Fe–Se配位键的半共格异质界面工程提高电池型超级电容器阳极的容量和倍率

低容量和低倍率限制了电池型超级电容阳极材料的大规模应用.本文通过构建一种具有半共格异质界面特性的Fe_(2)O_(3)/FeSe_(2)纳米结构作为先进的阳极材料来解决这一瓶颈.系列表征和第一性原理计算表明,这种特殊的异质界面不仅能自发产生较强的内建电场,从而提高电子传递速率和OH^(-)离子的吸附能力;还可使得活性物质与OH^(-)之间发生更多的氧化还原反应,并且使该反应体系更容易进行.基于上述优势,所制备出的阳极材料的最大比容量为199.2 mA h g^(-1)(1 A g^(-1)),并且在10 A g^(-1)下仍能保持105.8 mA h g^(-1),同时,经历5000次循环后,其比容量可维持初始值的90.2%.此外,以Fe_(2)O_(3)/FeSe_(2)作为阳极组装的非对称超级电容器在0.8 kW kg^(-1)时的能量密度为52.55 Wh kg^(-1),即使经历15,000次循环,该器件还能维持初始容量的91.2%.我们的工作为设计大容量和高倍率性能的电池型超级电容器阳极材料提供了一种创新性的策略,有望推动过渡金属化合物在储能系统中的大规模应用.

Dual-ion pre-inserted Mo glycerate template for constructing NiMo-OS core–shell structure with boosting performance in zinc ions hybrid supercapacitors

Zinc ion hybrid supercapacitors(ZHS)have received much attention due to the enhanced potential window range and high specific capacity.However,the appropriate positive materials with high electrochemical performance are still a challenge.Herein,NH_(4)^(+)and glycerate anions pre-inserted Mo glycerate(N-MoG)spheres are synthesized and serve as the template to form NH_(4)^(+)intercalated Ni_(3)S_(2)/Ni_(3)O_(2)(OH)_(4)@MoS_(2)core–shell nanoflower(N-NiMo-OS)in-situ grown on nickel foam(NF)(N-NiMo-OS/NF)by sulfurization treatment.Compared with the product using traditional MoG as a template,N-NiMo-OS/NF inheriting a larger core structure from N-MoG delivers enhanced space for ions transport and volume expansion during the energy storage process,together with the synergistic effects of multi-components and the heterostructure,the as-prepared N-NiMo-OS/NF nanoflower exhibits excellent performance for the battery-type hybrid supercapacitors(BHS)and ZHS devices.Notably,the ZHS device delivers superior electrochemical performance to the BHS device,such as a higher specific capacity of 327.5 mAh·g^(−1)at 1 A·g^(−1),a preeminent energy density of 610.6 Wh·kg^(−1)at 1710 W·kg^(−1),long cycle life.The in-situ Raman,ex-situ X-ray photoelectron spectroscopy(XPS),theoretical calculation demonstrate the extra Zn^(2+)insertion/extraction storage mechanism provides enhanced electrochemical performance for ZHS device.Therefore,the dual-ion pre-inserted strategy can be extended for other advanced electrode materials in energy storage fields.

Structural and Performance Regulation of Binary Transition-Metal Oxides Toward Supercapacitors:Advances and Prospects

Binary transition-metal oxides(BTMOs)are attractive candidates for advanced supercapacitors(SCs)because of their ultrahigh specific capacitance,tunable structures as well as morphologies,and low cost.To promote the practical application of BTMOs,their structure–performance relationship and developmental bottleneck should be further understood.In this review,the crystal structures and corresponding electrochemical properties of typical BTMOs in various aqueous electrolytes are briefly introduced.Some ingenious methods for improved electric conductivity,mainly including building integrated electrodes and composites,introducing oxygen vacancy,and element doping are carefully discussed.Some practicable ideas for boosting cycle stability through avoiding or alleviating agglomeration,volume change,and dissolution are provided in detail.Finally,the existing problems and challenges for structural and performance regulation of BTMOs are generalized.This review will support valuable information for building better SCs using BTMOs.

Nickel/cobalt based materials for supercapacitors

The electrode materials as the key component of supercapacitors have attracted considerable research interests, especially for nickel/cobalt based materials by virtue of their superior electrochemical performance with multiple oxidation states for richer redox reactions, abundant natural resources, lower prices and toxicity. There are many advanced electrodes based on the nickel/cobalt materials exploited for the application of supercapacitors, however, some controversial statements have induced some confusion. Herein, we refine the mechanism of energy storage for the nickel/cobalt based materials for supercapacitors and reclassify them into battery-type materials with the corresponding devices named as hybrid supercapacitors.