Sn‐MoS 2 ‐C@C Microspheres as a Sodium‐Ion Battery Anode Material with High Capacity and Long Cycle Life

Advanced Energy Materials

Liu

Wang

et al. 2019

209

149

Recently, room-temperature stationary sodium-ion batteries (SIBs) have received extensive investigations for large-scale energy storage systems (EESs) and smart grids due to the huge natural abundance and low cost of sodium. The SIBs share a similar "rocking-chair" sodium storage mechanism with lithium-ion batteries; thus, selecting appropriate electrodes with a low cost, satisfactory electrochemical performance, and high reliability is the key point for the development for SIBs. On the other hand, the carefully chosen elements in the electrodes also largely determine the cost of SIBs. Therefore, earth-abundantmetal-based compounds are ideal candidates for reducing the cost of electrodes. Among all the high-abundance and low-cost metal elements, cathodes containing iron and/or manganese are the most representative ones that have attracted numerous studies up till now. Herein, recent advances on both ironand manganese-based cathodes of various types, such as polyanionic, layered oxide, MXene, and spinel, are highlighted. The structure-function property for the iron-and manganese-based compounds is summarized and analyzed in detail. With the participation of iron and manganese in sodium-based cathode materials, real applications of room-temperature SIBs in large-scale EESs will be greatly promoted and accelerated in the near future.

Section: The Importance Of Developing High‐abundance and Low‐cost Catmentioning

confidence: 99%

High‐Abundance and Low‐Cost Metal‐Based Cathode Materials for Sodium‐Ion Batteries: Problems, Progress, and Key Technologies

Advanced Energy Materials

Liu

Wang

et al. 2019

209

149

“…In addition, sodium‐ion batteries (SIBs) and potassium‐ion batteries (KIBs) are getting more attention. But they have been hindered in practical applications, which stems from the lack of some suitable anode materials for hosting Na + /K + owing to their larger radius than Li + . So it is necessary to develop suitable anode materials for Na + /K + storage with excellent cyclic stability and high capacity.…”

Section: Introductionmentioning

confidence: 99%

Sandwich‐like MoS₂@SnO₂@C with High Capacity and Stability for Sodium/Potassium Ion Batteries

Yin

Zhang

2018

Small

165

Sandwich-like MoS @SnO @C nanosheets are prepared by facile hydrothermal reactions. SnO nanosheets can attach to exfoliated MoS nanosheets to prevent restacking of adjacent MoS nanosheets, and carbon transformed from polyvinylpyrrolidone is coated on MoS @SnO , forming a sandwich structure to maintain cycling stability. As an anode for sodium-ion batteries, the electrode greatly deliverers a high initial discharge specific capacity of 530 mA h g and maintains at 396 mA h g after 150 cycles at 0.1 A g . Even at a large current density of 1 A g , it can hold 230 mA h g after 450 cycles. Besides, as an anode for K storage, the electrode also shows a discharge capacity of 312 mA h g after 25 cycles at 0.05 A g . This work may provide a new strategy to prepare other composites which can be applied to new kind of rechargeable batteries.

“…The large volume expansion of the electrode causes a rupture of the fragile SEI leading to a poor coulombic efficiency and a rapidly fading capacity . Therefore, a carbon coating of an electrode is considered an attractive approach for electron conduction and also, it acts as a barrier between the electrolyte and active material, to strengthen its structural integrity and improve on the cyclic stability . However, coating with excessive carbon layers not only generates an obstacle for the metal ions diffusion that will adversely affect the specific capacity but also introduces large volumes of inactive materials in such an electrode.…”

mentioning

confidence: 99%

A 3D Trilayered CNT/MoSe₂/C Heterostructure with an Expanded MoSe₂ Interlayer Spacing for an Efficient Sodium Storage

Yousaf

Wang

Advanced Energy Materials

et al. 2019

233

157

attention because of its low cost and abundant supply of sodium. [1][2][3] However, because of its narrow interlayer spacing ≈0.34 nm, the larger size of Na + compared to Li + makes it difficult if not unsuitable for intercalation in graphite, which is commercially employed for LIB. [4][5][6] Further, the large radius of Na + in SIB electrodes produces sluggish electrochemical kinetics, provides higher diffusion barriers, and causes large volume expansion which leads to low rate capability and poor cyclic stability. [7,8] The ionization potential of Na + is also lower than Li + which results in a lower operating voltage and consequently, a lower energy density. [9] A lot of efforts in the development of advanced anode materials for SIBs have been proposed to address these issues.Recently, 2D transition metal dichalcogenides (TMDCs) have received considerable attention in electrochemical energy storage and conversion devices due to their layered structure, and the favorable electronic, chemical, and mechanical properties and stability. [10][11][12] TMDCs such as MoS 2 are often considered a promising anode candidate for LIBs. [13] However, when MoS 2 is employed in SIBs, it displays a lower capacity and a poor cyclic stability as a result of the low intrinsic conductivity and the small interlayer distance (≈0.62 nm). [14] In contrast, MoSe 2 possesses a slightly larger interlayer distance (≈0.64 nm) and better electrical conductivity due to small bandgap (≈1.1 eV). Moreover, it possesses higher theoretical capacity (≈422 mAh g −1 ) [10,15] than graphite (≈35 mAh g −1 ) [6] which makes it one of the most promising TMDC candidates for SIBs. However, the practical applications of MoSe 2 as an anode is limited by capacity fading due to the large volume expansion during long charging/discharging processes and the poor rate capability due to the low intrinsic electrical conductivity. [10] Modifying the nanostructure of the SIB electrodes can often solve some of these problems. For example, expanding the interlayer distance of MoSe 2 can lead to an improvement of the Na + storage and reducing the Na + diffusion barrier energy can enhance the reaction kinetics for the Na + intercalation/deintercalation. [16] Due to the high surface energy and weak van der Waal interactions between layers, Freestanding composite structures with embedded transition metal dichalcogenides (TMDCs) as the active material are highly attractive in the development of advanced electrodes for energy storage devices. Most 3D electrodes consist of a bilayer design involving a core-shell combination. To further enhance the gravimetric and areal capacities, a 3D trilayer design is proposed that has MoSe 2 as the TMDC sandwiched in-between an inner carbon nanotube (CNT) core and an outer carbon layer to form a CNT/ MoSe 2 /C framework. The CNT core creates interconnected pathways for the e − /Na + conduction, while the conductive inert carbon layer not only protects the corrosive environment between the electrolyte and MoSe 2 but also is fully tunable fo...