Conversion‐Type MnO Nanorods as a Surprisingly Stable Anode Framework for Sodium‐Ion Batteries

Abstract

The emergence of nanomaterials in the past decades has greatly advanced modern energy storage devices. Nanomaterials can offer high capacity and fast kinetics yet are prone to rapid morphological evolution and degradation. As a result, they are often hybridized with a stable framework in order to gain stability and fully utilize its advantages. However, candidates for such framework materials are rather limited, with carbon, conductive polymers, and Ti-based oxides being the only choices; note these are all inactive or intercalation compounds. Conventionally, alloying-/conversiontype electrodes, which are thought to be electrochemically unstable by themselves, have never been considered as framework materials. This concept is challenged. Successful application of conversion-type MnO nanorod as a anode framework for high-capacity Mo 2 C/MoO x nanoparticles has been demonstrated in sodium-ion batteries. Surprisingly, it can stably deliver 110 mAh g −1 under extremely high rate of 8000 mA g −1 (≈70 C) over 40 000 cycles with no capacity decay. More generally, this is considered as a proof of concept and much more alloying-/conversion-type materials are expected to be explored for such applications.

Novel Designed MnS‐MoS2 Heterostructure for Fast and Stable Li/Na Storage:Insights into the Advanced Mechanism Attributed to Phase Engineering

“…The diffusion coefficient D can be calculated according to , where i is applied constant electric current, V m is the molar volume of active material, A is the total contact area between electrolyte and electrodes, F is Faraday constant, Z A is the valence of the species, d E /dδ is the slope of the coulometric titration curve, and t is the time duration of the constant current pulse. [ 43 ] Figure 4d shows the GITT test curves of the MnS‐MoS 2 heterostructure, the bare MnS, and the bare MoS 2 respectively. The calculated diffusion coefficient of MnS‐MoS 2 heterostructure is in the range of 10 −14 –10 −13 cm 2 s −1 , an order of magnitude larger than the diffusion coefficient of the pure MnS (10 −16 –10 −14 cm 2 s −1 ) and pure MoS 2 (10 −15 –10 −14 cm 2 s −1 ).…”

Binary-Metal Mn2SnO4 Nanoparticles and Sn Confined in a Cubic Frame with N-Doped Carbon for Enhanced Lithium and Sodium Storage

“…The other peak at 0.07 V corresponds to the formation of alloy Na x Sn (eq ). In the initial anodic scan, the peaks ranging from 0.3 to 0.9 V are related to the desodiation processes of Na x Sn. , The other two small peaks at 1.14 and 2.0 V are attributed to the oxidation of Sn and Mn, respectively (eqs and ). , Figure S9b shows the XRD patterns of the Sn@Mn 2 SnO 4 -NC electrode after discharge and charge. The peaks of Mn and Na x Sn can be found at the state of discharge to 0.01 V, indicating the intercalation of Na + .…”

Electrochemical Performance and Mechanism of Surface‐Fluorinated Fe3O4 as Stable Anode for Lithium‐Ion Batteries

“…With the rapid development of portable electronic products and electric vehicles, lithium‐ion batteries (LIBs) have attracted great interest. [ 1 ] Unfortunately, owing to the limited specific capacity of commercial electrode materials (such as graphite), the current LIBs cannot meet the growing demand. Thus, numerous researches have been carried out for the purpose of developing electrode materials with superior energy density, long cycle life, and fast charging features.…”