Carbon embedded SnSb composite tailored by carbothermal reduction process as high performance anode for sodium-ion batteries

Enhancing the Electrochemical Performance of SbTe Bimetallic Anodes for High-Performance Sodium-Ion Batteries: Roles of the Binder and Carbon Support Matrix

Synergism between the alloy materials and the carbon support matrix, in conjunction with the binder and electrolyte additives, is of utmost importance when developing sodium-ion batteries as viable replacements for lithium-ion batteries. In this study, we demonstrate the importance of the binder and carbon support matrix in enhancing the stabilities, cyclabilities, and capacity retentions of bimetallic anodes in sodium-ion batteries. SbTe electrodes containing 20%, 30%, and 40% carbon were fabricated with polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA) binders, and electrochemically evaluated at a current rate of 100 mA g⁻¹ using electrolytes with 0%, 2%, and 5% added fluoroethylene carbonate (FEC). The electrodes with the PVDF binder in cells with 5% FEC added to the electrolyte showed capacity retentions that increased with increasing carbon percentage, delivering reversible capacities of 34, 69, and 168 mAh g⁻¹ with 20%, 30%, and 40% carbon; these electrodes retained 8.1%, 17.4%, and 44.8% of their respective capacities after 100 cycles. However, electrodes composed of the PAA binder in cells with 5% FEC added to the electrolyte delivered reversible capacities of 408, 373, and 341 mAh g⁻¹ with 20%, 30%, and 40% carbon; 93.5%, 93.4%, and 94.4% of their respective capacities were retained after 100 cycles. The carbon support matrix plays a significant role in improving the stability, cyclability, and capacity retention of the electrode. However, when the tradeoff between capacity and cyclability associated with carbon percentage is considered, the binder plays a significantly more prominent role in achieving high capacities, high cyclabilities, and enhanced retention rates.

Carbon-Based Alloy-Type Composite Anode Materials toward Sodium-Ion Batteries

In the scenario of renewable clean energy gradually replacing fossil energy, grid-scale energy storage systems are urgently necessary, where Na-ion batteries (SIBs) could supply crucial support, due to abundant Na raw materials and a similar electrochemical mechanism to Li-ion batteries. The limited energy density is one of the major challenges hindering the commercialization of SIBs. Alloy-type anodes with high theoretical capacities provide good opportunities to address this issue. However, these anodes suffer from the large volume expansion and inferior conductivity, which induce rapid capacity fading, poor rate properties, and safety issues. Carbon-based alloy-type composites (CAC) have been extensively applied in the effective construction of anodes that improved electrochemical performance, as the carbon component could alleviate the volume change and increase the conductivity. Here, state-of-the-art CAC anode materials applied in SIBs are summarized, including their design principle, characterization, and electrochemical performance. The corresponding alloying mechanism along with its advantages and disadvantages is briefly presented. The crucial roles and working mechanism of the carbon matrix in CAC anodes are discussed in depth. Lastly, the existing challenges and the perspectives are proposed. Such an understanding critically paves the way for tailoring and designing suitable alloy-type anodes toward practical applications.