Low‐Temperature Synthesis of Amorphous Silicon and Its Ball‐in‐Ball Hollow Nanospheres as High‐Performance Anodes for Sodium‐Ion Batteries

Abstract

silicon (c-Si) possesses extremely finite sodium storage capability based on firstprinciple calculations due to the large energy consumption of sodium insertion into c-Si. [6,7] On the contrary, amorphous silicon (a-Si) is capable of holding 0.76 Na atom each Si, the capacity is highly 725 mAh g -1 correspondingly. [7] Till now, there is only a little literature dedicated to the study of a-Si as an anode material for SIBs. [8][9][10][11][12] One reason for this is the preparation difficultly of a-Si. Expensive and unstable raw materials such as silicon tetrachloride and complicated devices are usually involved. Moreover, most of these a-Si have no special structures, leading to unsatisfactory Na-storage performance. Silica with a non-toxic, easy to use, and stable chemical property, is abundant in nature. Carbothermic reduction is a common industrial procedure to manufacture solar energy c-Si from quartz sand (natural mineral) in an electric arc furnace described in Equation (1). [13] Since Nature published the first report in 2007 on using magnesiothermic reduction to prepare c-Si from diatom frustules (marine plant) according to Equation (2), [14] the method has been extensively applied in the field of LIBs. [4,5,15] Therefore, it will be of great significance to develop a low-temperature facile approach to produce carefully crafted a-Si structures from silica for SIBs.

Amorphous Materials for Lithium‐Ion and Post‐Lithium‐Ion Batteries

“…[135] Amorphous hollow silicon nanospheres produced via low-temperature synthesis can also enhance the cycling stability of batteries. [137] There are many other reported amorphous anode materials such as MoS x , [138] P 2 S 5 , [139] MoS 3 , [140] MoS 2 -MoO 3 -carbon, [141] FeOOH, [142] CuSnO 3 , [143] CoS, [144] CoMoS 4 , [145] Co 2 P, [146] Bi 2 S 3 , [147] P 4 SSe 2 , [148] antimony (Sb), [149] Sb 2 S 3 , [150] Sb 2 Se 3 , [151] SnSe, [152] Sn 2 P 2 O 7 , [153] SnO 2 , [154] TiO 2 , [155] V 2 O 5 , [156] VO 2 , [157] Zn 2 V 2 O 7 , [158] phosphorus (P), [159] Co─Sn─S, [160] SnO x P y , [161] SnO x , [162] zinc oxysulfide, [163] etc. In the future, it is necessary to further evaluate the index parameters of the reported amorphous anode materials from the perspective of commercialization.…”

Structural Control and Optimization Schemes of Silicon‐Based Anode Materials

“…[ 134 ] Li et al developed a new method called “sodiothermic reduction” for the preparation of amorphous silicon hollow nanospheres at lower temperatures and designed amorphous silicon matrix composites with yolk–shell structure by deposition of alumina atomic layers, in situ chemical polymerization of pyrrole, and dilute hydrochloric acid etching; the obtained composites all showed very good electrochemical properties as anode materials for sodium‐ion batteries, which are useful for the study of amorphous silicon anode materials for LIBs. [ 135 ] A‐Si preparation into thin films can shorten the ion diffusion length, thus promoting ion transport and storing more Li. [ 136 ] Thicker films are needed to meet the high energy density requirements for meeting LIBs, but increasing the thickness of the film will make the adhesion between the film and the collector decrease, leading to the detachment of both and thus the electrochemical performance, [ 137 ] so there is a need to reconcile the relationship between thickness and electrochemical performance as required.…”

In Situ Flash Synthesis of Ultra-High-Performance Metal Oxide Anode through Shunting Current-Based Electrothermal Shock

“…However, the actual performance of TMOs is much lower than expected as their capacity rapidly decays even at lower current rates due to disintegration/fragmentation of the electrode material as a result of significant volume changes during charging/discharging, and scientists have proposed the production of a variety of porous nanostructured materials to address these issues. , These materials involve well-organized hierarchical micro/nanostructures composed of secondary superstructures formed through the ordered assembly of nanounits. TMOs with a hierarchical arrangement benefit from the nanoscale structure (e.g., nanoparticles, nanosheets, and nanorods), as well as the nanoscale assemblies (such as mesoporous nanocubes, hollow nanospheres, ball-in-ball nanospheres, and mesoporous spindle-like nanostructure). These hierarchical structures exhibit a buffering effect, effectively mitigating structural strain and promoting improved contact between the electrode and electrolyte interface. , Additionally, carbon-based additives for forming nanocomposites with TMOs nanostructures not only improve the mechanical flexibility of the mixed materials to buffer volume changes during charging and discharging but also improve the electrical conductivity.…”