Design And Preparation Of Antimony/Bismuth-Based Anode Materials And Sodium Storage Performance For Sodium-Ion Batteries

Metallic antimony and bismuth are ideal candidates for sodium-ion battery anodes,because they have high theoretical capacities and moderate working potentials.However,they also face a common challenge,which is the huge volume change during sodiation and desodiation,leading to the destruction and failure of the electrode structure.To solve this problem,this paper improves the sodium storage performance of antimony and bismuth based electrodes by constructing micro-nano structures on the current collector and alloying with other metals.The main results are as follows:（1）A nano-porous copper（NPCu）with a pore size of about 300 nm was prepared as a current collector by chemical oxidation and etching methods,and an Sb layer was electrochemically deposited on its surface（NPCu@Sb）.The electrode structure not only can accommodate the volume change during cycling,maintain the electrode integrity and good electrical contact,avoid the increase of electrochemical polarization,but also can provide fast transport channels for Na⁺.Therefore,NPCu@Sb exhibits excellent long cycle life and high-rate capacity,with a high reversible capacity of 602.4 m Ah g^-1 and a high retention rate of 93.9%after 300 cycles at 0.3 A g^-1,and a high capacity of 502.8 m Ah g^-1 at 10 A g^-1.（2）An In Sb alloy layer was electrochemically deposited on a three-dimensional porous copper,and the sodium storage performance of Sb electrode was synergistically improved by Indium element and three-dimensional porous structure.The 3D In Sb electrode showed a capacity retention rate of 67.5%after 300 cycles at a current density of 0.3 A g^-1;a capacity of193.3 m Ah g^-1 and a capacity retention rate of 72.6%after 400 cycles at a current density of 10A g^-1;and a capacity of 201.8 m Ah g^-1 at a current density of 20 A g^-1.（3）Bi nanoparticles were directly electrochemically deposited on a three-dimensional porous copper,and a three-dimensional porous bismuth electrode was prepared and characterized and tested for its performance.The results showed that the electrode had excellent electrochemical performance,with a high initial reversible specific capacity of 464.2 m Ah g^-1at a current density of 10 A g^-1,and could stably cycle for more than 15000 cycles.It also had good rate performance,with reversible capacities of 453.1,445.6,447.0,449.9,451.2,451.8,450.7,448.1 and 442.8 m Ah g^-1 at current densities of 0.1,0.3,0.5,1,2,3,5,10 and 20 A g^-1,respectively.SEM analysis revealed that Bi nanoparticles evolved into three-dimensional networked bismuth nanowires during cycling,which helped to mitigate the effect of volume expansion and enhance the efficiency of ion transport.