Confined Selenium in N-Doped Mesoporous Carbon Nanospheres for Sodium-Ion Batteries

Abstract

In this paper, we have adopted a simple and etching-free method to prepare mesoporous carbon spheres in one step. Selenium can be deposited in the internal cavity, which can avoid pulverization due to the combined effect of volume expansion and a solid−electrolyte interphase (SEI) film while charging and discharging. Therefore, the as-prepared selenium and nitrogen codoped mesoporous carbon nanosphere (Se@NMCS) composites can deliver an outstanding sodium-storage performance of 336.6 mAh g −1 at a present density of 200 mA g −1 and great long-cycling performance. For a further understanding of the Na + storage mechanism of the Se@NMCS anode in sodium-ion batteries (SIBs), the phase evolution of the Se@NMCS anode has been explored during the charge/discharge process by conducting in situ Raman investigation.

Co‐MOF derived MoSe 2 @ CoSe 2 /N‐doped carbon nanorods as high‐performance anode materials for potassium ion batteries

“…In the Se 3d spectrum (Figure 2F), a large peak and another small peak are discerned. The large peak was deconvoluted into two sub‐peaks corresponding to Se 3d 5/2 (54.4 eV) and Se 3d 3/2 (55.3 eV); this result is in agreement with reported studies 34,35 . The small peak located at 59.4 eV was assigned to the SeO bond originating from the partial surface oxidation of Se.…”

Amorphous Se Restrained by Biomass-Derived Defective Carbon for Stable Na–Se Batteries

“…Figure b displays the voltage profiles of the Se@NOPCC electrode at 50 mA g –1 with a voltage window of 0.8–2.8 V. The first discharge slope plateau around 1.15 V is lower than the subsequent cycles caused by the activation process, which agrees well with the CV curves. The irreversible capacity during the first cycle is mainly due to the side reactions between the electrolyte and the carbon substrate as well as the formation of SEI. , The electrochemical performance of the NOPCC electrode is also shown in Figure S12, which shows a low reversible capacity of 8.5 mAh g –1 . The high irreversible capacity during the first cycle of the NOPCC electrode resulted in the highly irreversible reactions in the Se@NOPCC electrode.…”

“…As linearly fitted with log­( i ) vs log­( v ) in Figure S17a, the b values of the peaks R1, R2, and O are calculated to be 0.61, 0.96, and 0.70, respectively, indicating that the electrochemical process is synergistically controlled by pseudocapacitance and ion diffusion behaviors. Moreover, the contributions of pseudocapacitance and ion diffusion can be calculated by the equation of i = k 1 v + k 2 v 1/2 , in which k 1 v and k 2 v 1/2 are the pseudocapacitance and ion-diffusion contributions, respectively. ,, The contribution of the pseudocapacitive process at 0.2 mV s –1 is 60.4%, as shown in Figure S17b. With the scan rate increasing from 0.3 to 0.8 mV s –1 , the ratio of capacitive contribution rises from 66.8 to 84.6 (Figure d), accounting for the high-rate capability.…”

“…The irreversible capacity during the first cycle is mainly due to the side reactions between the electrolyte and the carbon substrate as well as the formation of SEI. 7,42 The electrochemical performance of the NOPCC electrode is also shown in Figure S12, which shows a low reversible capacity of 8.5 mAh g −1 . The high irreversible capacity during the first cycle of the NOPCC electrode resulted in the highly irreversible reactions in the Se@NOPCC electrode.…”

Deliberate introduction of mesopores into microporous activated carbon toward efficient Se cathode of Na−Se batteries

“…8,[14][15][16][17][18][19][20][21] Among such battery systems, NaÀSe batteries have recently emerged as a potentially viable alternative owing to the abundance and low cost of Na resources. 14,22 Since the pioneering work by Amine's group in 2012, 23 numerous carbon materials have been used as Se cathodes to achieve enhanced Na + storage performance; such materials include carbon nanofibers, [24][25][26][27] carbon micro/ nanospheres, [28][29][30][31][32][33][34] carbon nanosheets, 35,36 reduced graphene oxide, 37 carbon nanotubes, 38 and so on. [39][40][41][42][43][44][45][46][47] Doped carbon and some metal compound-based Se cathodes have also been reported to act as effective polyselenide adsorbents during sodiation/desodiation processes.…”