Surface‐Dominated Sodium Storage Towards High Capacity and Ultrastable Anode Material for Sodium‐Ion Batteries

Abstract

The development of sodium-ion batteries is hindered by the poor Na + transport kinetics and structural instability of electrode materials during Na + intercalation/deintercalation. In this work, surface-dominated Na storage is demonstrated on the oxygen-functionalized graphene nanosheets (FGS) with fast surface redox reaction and robust structural stability. The FGS samples with tunable oxygen contents and species are fabricated via a two-step thermal exfoliation method from graphite oxides. The surface-induced oxygen functional groups can serve as the surface-redox sites for the FGS electrode, attaining a high specific capacity of 603 mAh g −1 at a current density of 0.05 A g −1 , excellent rate capability (214 mAh g −1 at 10 A g −1 ), and ultrastable cycling stability (capacity retention close to 100% after 10 000 cycles at 5 A g −1 ). Even at a slow scan rate of 0.1 mV s −1 for cyclic voltammetry, about 67.7% capacity is contributed from the surface adsorption/desorption and surface-redox reaction, suggesting surface-dominated Na storage for the FGS-700 (FGS sample obtained at 700 °C) electrode. The present work demonstrates that the surface oxygen functionalization is an effective strategy to develop high-performance graphene-based anodes due to the surface-dominated Na storage with improved reaction kinetics and suppressed structural variation.

Few‐Layered Tin Sulfide Nanosheets Supported on Reduced Graphene Oxide as a High‐Performance Anode for Potassium‐Ion Batteries

“…In striking contrast, the SnS 2 @rGO‐1, SnS 2 @rGO‐4, and SnS 2 electrodes exhibit much lower reversible capacities of 359, 373, and 271 mAh g −1 with low ICEs of 42.7%, 44.4%, and 36.5% (Figure S9, Supporting Information), respectively. The inferior performances of these electrodes indicate that it is critical to control the nanoscale morphology of SnS 2 , as well as the content of graphene‐based conductive scaffolds . In our work, the pure SnS 2 electrode shows the lowest ICE, which is one of the major problems of anode materials based on conversion and alloy reactions .…”

“…These results indicate that serious intermediate products are formed during the potassiation of SnS 2 @rGO‐2. Notably, the lowest reduction peak of SnS 2 @rGO‐2 is 0.10 V versus K + /K in PIBs instead of 0.01 V versus Na + /Na in SIBs, suggesting the less possibility of dendrite formation in PIBs as compared to that in SIBs (Figure S8, Supporting Information) . Thus, PIBs could be safer than SIBs when using SnS 2 @rGO‐ x as anode.…”

“…Meanwhile, the SnS 2 @rGO‐2 electrode exhibits the highest ICE among these four samples, indicating that the amount of rGO plays the key role in influencing the ICE of the electrode. When the content of rGO is high, exposed rGO can react with K + in the electrolyte directly, causing some irreversible reactions between the oxygen functional groups on the surface of rGO nanosheets and K + ions . On the contrary, when the content of rGO is low, SnS 2 nanoparticles tend to aggregate on the surface of rGO, lowering the reversibility of alloying and conversion reactions by the coarsening of Sn particles in the electrode .…”

Nitrogen‐Doped Hard Carbon on Nickel Foam as Free‐Standing Anodes for High‐Performance Sodium‐Ion Batteries

“…The crystal structures of NC/NF‐700, NC/NF‐800, and NC/NF‐900 were further characterized by XRD and Raman. The XRD pattern (Figure a) displays two broad peaks at 2θ≈23.5° and 43.5°, corresponding to the (002) and (100) diffraction, respectively . The broad and low intensity peaks suggest a low degree of graphitization.…”

Constructing Multichannel Carbon Fibers as Freestanding Anodes for Potassium‐Ion Battery with High Capacity and Long Cycle Life

“…To distinguish the contribution of capacitive-and diffusion-controlled processes, the mixed current (i) at a fixed voltage (V) is separated into two parts based on the following equation [43,44] i…”