Fast Sodium Storage in TiO₂@CNT@C Nanorods for High‐Performance Na‐Ion Capacitors

Abstract

Na‐ion capacitors have attracted extensive interest due to the combination of the merits of high energy density of batteries and high power density as well as long cycle life of capacitors. Here, a novel Na‐ion capacitor, utilizing TiO2@CNT@C nanorods as an intercalation‐type anode and biomass‐derived carbon with high surface area as an ion adsorption cathode in an organic electrolyte, is reported. The advanced architecture of TiO2@CNT@C nanorods, prepared by electrospinning method, demonstrates excellent cyclic stability and outstanding rate capability in half cells. The contribution of extrinsic pseudocapacitance affects the rate capability to a large extent, which is identified by kinetics analysis. A key finding is that ion/electron transfer dynamics of TiO2@CNT@C could be effectively enhanced due to the addition of multiwalled carbon nanotubes. Also, the biomass‐derived carbon with high surface area displays high specific capacity and excellent rate capability. Owing to the merits of structures and excellent performances of both anode and cathode materials, the assembled Na‐ion capacitors provide an exceptionally high energy density (81.2 W h kg−1) and high power density (12 400 W kg−1) within 1.0–4.0 V. Meanwhile, the Na‐ion capacitors achieve 85.3% capacity retention after 5000 cycles tested at 1 A g−1.

Flexible Quasi‐Solid‐State Sodium‐Ion Capacitors Developed Using 2D Metal–Organic‐Framework Array as Reactor

“…The energy density and power density values are calculated by integrating galvanostatic discharge curves and using the total mass of the two electrodes. The energy densities of the present quasi-solid-state NIC device are considerably higher than those values of the state-of-the-art reported NICs [23,[26][27][28][29][30][31][32][45][46][47] (Table S2, Supporting Information) and other energy storage systems such as lithium ion capacitors, [48][49][50] aqueous asymmetric SCs, [51,52] ionic liquid-based SCs, [33,53] and Ni/Fe batteries. Even at an extremely high power density of 48 kW kg −1 , the NIC can still deliver 49 W h kg −1 .…”

3D Cube‐Maze‐Like Li‐Rich Layered Cathodes Assembled from 2D Porous Nanosheets for Enhanced Cycle Stability and Rate Capability of Lithium‐Ion Batteries

“…Recently, Li-rich cathode materials (LMNCO), x Li 2 MnO 3 ·(1 − x) LiTMO 2 (0 < x < 1, TM = Mn, Ni, Co, etc. [5][6][7][8][9] On the basis of this, extensive efforts have been devoted to develop nanometersized materials and great progresses have been achieved over the past several years, such as construction of nanoplates, [5] nanowires, [10] nanoparticles, [11] and nanorods, [12] which possess a short Li + diffusion pathway thanks to their diminished dimensions. [3] Nevertheless, the sluggish diffusion of electrons and lithium ions within LMNCO results in electrode polarization and inferior rate capability.…”

LiFePO4 Particles Embedded in Fast Bifunctional Conductor rGO&C@Li3V2(PO4)3 Nanosheets as Cathodes for High‐Performance Li‐Ion Hybrid Capacitors

“…[5,15,51,52] Density functional theory (DFT) computations were also performed to get insight into the superior rate performance. These behaviors are also similar to what has been reported in other bulk materials with surface-controlled lithium storage mechanism.…”

“…Consequently, lithium-ion batteries (LIBs) are widely regarded as ideal energy storage devices for EVs due to their high energy density. [5][6][7] Olivine LiFePO 4 (LFP) is a promising cathode material due to its relatively high theoretical capacity of 170 mAh g −1 , good thermal stability, and low cost. An alternative choice is to trade energy density for power density like supercapacitors, in which energy storage is realized by surface adsorption and Faradaic reactions.…”