An aqueous zinc-ion hybrid super-capacitor for achieving ultrahigh-volumetric energy density

Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems,However,the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices,In this work,the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density threedimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte.Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure,the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L,as well as an excellent long cycle life(80% retention after 30,000 cycles at 10 A/g),which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors.This device,based on the fast ion adsorption/deso rption on the capacitor-type graphene cathode and reversible Zn^(2+) plating/stripping on the battery-type Zn anode,which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.

A Bifunctional-Modulated Conformal Li/Mn-Rich Layered Cathode for Fast-Charging,High Volumetric Density and Durable Li-Ion Full Cells

Lithium-and manganese-rich(LMR)layered cathode materials hold the great promise in designing the next-generation high energy density lithium ion batteries.However,due to the severe surface phase transformation and structure collapse,stabilizing LMR to suppress capacity fade has been a critical challenge.Here,a bifunctional strategy that integrates the advantages of surface modification and structural design is proposed to address the above issues.A model compound Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(MNC)with semi-hollow microsphere structure is synthesized,of which the surface is modified by surface-treated layer and graphene/car-bon nanotube dual layers.The unique structure design enabled high tap density(2.1 g cm^(−3))and bidirectional ion diffusion pathways.The dual surface coatings covalent bonded with MNC via C-O-M linkage greatly improves charge transfer efficiency and mitigates electrode degradation.Owing to the synergistic effect,the obtained MNC cathode is highly conformal with durable structure integrity,exhibiting high volumetric energy density(2234 Wh L^(−1))and predominant capacitive behavior.The assembled full cell,with nanograph-ite as the anode,reveals an energy density of 526.5 Wh kg^(−1),good rate performance(70.3%retention at 20 C)and long cycle life(1000 cycles).The strategy presented in this work may shed light on designing other high-performance energy devices.

Interface-Structure-Modulated CuF_(2)/CF_(x) Composites for High-Performance Lithium Primary Batteries

Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.

利用钴酸锂构筑高体积比容量和高质量比容量硫电极

锂-硫电池的质量能量密度较高,但其体积能量密度却并不理想.为了提高锂-硫电池的体积能量密度,需要重点改善复合硫电极的结构和密度.本研究引入高密度的钴酸锂纳米纤维作为硫的载体材料.钴酸锂的振实密度高达2.26 g cm^(−3),硫/钴酸锂电极的密度和孔隙率分别为0.85 g cm^(−3)和61.2%.研究发现,钴酸锂是一种优异的电催化剂,可以加速活性物质硫的反应速率.因此,硫/钴酸锂正极兼具致密的电极结构和良好的电化学活性,其体积能量密度得到显著提升,并同时保持较高的质量能量密度.当硫的面负载量为5.1 mg cm^(−2)时,整体硫/钴酸锂电极的体积和质量比容量分别为724 mA h cm^(−3)和848 mA h g^(−1).此外,钴酸锂可以减缓多硫化锂的穿梭并降低多硫化锂对锂负极的腐蚀,提高锂负极的稳定性.