Efficient Sodium Storage in Rolled‐Up Amorphous Si Nanomembranes

Abstract

Alloying-type materials are promising anodes for high-performance sodium-ion batteries (SIBs) because of their high capacities and low Na-ion insertion potentials. However, the typical candidates, such as P, Sn, Sb, and Pb, suffer from severe volume changes (≈293-487%) during the electrochemical reactions, leading to inferior cycling performances. Here, a high-rate and ultrastable alloying-type anode based on the rolled-up amorphous Si nanomembranes is demonstrated. The rolled-up amorphous Si nanomembranes show a very small volume change during the sodiation/desodiation processes and deliver an excellent rate capability and ultralong cycle life up to 2000 cycles with 85% capacity retention. The structural evolution and pseudocapacitance contribution are investigated by using the ex situ characterization techniques combined with kinetics analysis. Furthermore, the mechanism of efficient sodium-ion storage in amorphous Si is kinetically analyzed through an illustrative atomic structure with dangling bonds, offering a new perspective on understanding the sodium storage behavior. These results suggest that nanostructured amorphous Si is a promising anode material for high-performance SIBs.

Explicating the Sodium Storage Kinetics and Redox Mechanism of Highly Pseudocapacitive Binary Transition Metal Sulfide via Operando Techniques and Ab Initio Evaluation

“…Sodium‐ion batteries (SIBs) are often described as one of the most promising postlithium technologies primarily due to sodium's abundance and economic advantage . However, choosing the appropriate anode material remains as the primal concern of SIBs due to the low capacity of intercalation‐based materials and performance fading of conversion and alloying‐based anodes due to the inherent structural frailties . In addition, SIBs prospects are also heavily impeded by the inept rate performance due to much heavier Na‐ions which greatly affects the realization of its potential applications …”

Hierarchically Nanoporous Pyropolymers Derived from Waste Pinecone as a Pseudocapacitive Electrode for Lithium Ion Hybrid Capacitors

“…Therefore, the gradual capacitance growth on the oxygen-rich 6-WP-HPPs could be attributed to pseudocapacitive lithium ion storage. The pseudocapacitive lithium ion storage ratio in overall capacitance can be calculated by using the followed equation, i 1/2 , where ν is the sweep rate [49][50][51] . The pseudocapacitance ratio of 6-WP-HPPs is calculated as ~35% [ Fig.…”

Peering into Alloy Anodes for Sodium‐Ion Batteries: Current Trends, Challenges, and Opportunities

“…In addition, capacity retentions of 94.5%, 89.1%, 81.6%, 75.4%, and 65.9% are achieved at 100, 500, 1000, 2000, and 5000 mA g −1 , respectively. Followed by those previous study, Huang et al designed a rolled‐up nanomembrane architecture to improve the sodium storage properties of amorphous Si (a‐Si) . Experimental results show that dangling bonds of a‐Si significantly improve the Na + transport kinetics by reducing the energy barrier for Na diffusion and provide additional surface for Na + storage capacity ( Figure a).…”

“…Furthermore, the theory is further supported by noticing limited Na uptake in crystalline Si. Surprisingly, the replacement of crystalline with amorphous structure make the Na system works . It is believed that the large interstitial sites of amorphous structure are responsible for the more favorable binding energy and reduction in activation barrier for Na diffusion, giving rise to facile Na intercalation and migration .…”