High-energy batteries with low cost are urgently needed in the field of large-scale energy storage, such as grid systems and renewable energy sources. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with alloy-based anodes provide huge potential due to their earth abundance, high capacity, and suitable working potential, and are recognized as attractive alternatives for next-generation batteries system. Although some important breakthroughs have been reported, more significant improvements are still required for long lifetime and high energy density. Herein, the latest progress for alloy-based anodes for SIBs and PIBs is summarized, mainly including Sn, Sb, Ge, Bi, Si, P, and their oxides, sulfides, selenides, and phosphides. Specifically, the material designs for the desired Na+ /K+ storage performance, phase transform, ionic/electronic transport kinetics, and specific chemical interactions are discussed. Typical structural features and research strategies of alloy-based anodes, which are used to facilitate processes in battery development for SIBs and PIBs, are also summarized. The perspective of future research of SIBs and PIBs is outlined.

Recent Progress on the Alloy-Based Anode for Sodium-Ion Batteries and Potassium-Ion Batteries.

Sodium-ion batteries (SIBs) have received great attention due to the low cost and abundance of sodium resources, and their chemical/electrochemical properties are similar to those of established lithium-ion batteries. In the past few years, we have witnessed the resuscitation and rapid development of various advanced electrode materials. Rationally designed nanostructures endow the electrodes with high reversible capacity, superior rate capability, and long-term cyclability. In this Review, we summarize some recent research progress in the rational design and synthesis of nanostructured electrode materials with controlled shape, structural complexity, composition, and boosted sodium storage performance. We seek to provide some understanding on the effect of nanostructure engineering on the sodium storage properties of electrode materials. It is thus anticipated that this Review will shed some light on the development of high-performance electrode materials for advanced SIBs.

Nanostructured Electrode Materials for Advanced Sodium-Ion Batteries

Nature of FeSe2/N-C Anode for High Performance Potassium Ion Hybrid Capacitor

Sodium-based dual-ion batteries (Na-DIBs) show a promising potential for large-scale energy storage applications due to the merits of environmental friendliness and low cost. However, Na-DIBs are generally subject to poor rate capability and cycling stability for the lack of suitable anodes to accommodate large Na+ ions. Herein, we propose a molecular grafting strategy to in situ synthesize tin pyrophosphate nanodots implanted in N-doped carbon matrix (SnP2O7@N-C), which exhibits a high fraction of active SnP2O7 up to 95.6 wt% and a low content of N-doped carbon (4.4 wt%) as the conductive framework. As a result, this anode delivers a high specific capacity ∼400 mAh g-1 at 0.1 A g-1, excellent rate capability up to 5.0 A g-1 and excellent cycling stability with a capacity retention of 92% after 1200 cycles under a current density of 1.5 A g-1. Further, pairing this anode with an environmentally friendly KS6 graphite cathode yields a SnP2O7@N-C||KS6 Na-DIB, exhibiting an excellent rate capability up to 30 C, good fast-charge/slow-discharge performance and long-term cycling life with a capacity retention of ∼96% after 1000 cycles at 20 C. This study provides a feasible strategy to develop high-performance anodes with high-fraction active materials for Na-based energy storage applications.

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Molecular grafting towards high-fraction active nanodots implanted in N-doped carbon for sodium dual-ion batteries.

Sodium-ion batteries (SIBs) have drawn enormous attention in the past few years from both academic and industrial battery communities in view of the fascinating advantages of rich abundance and low cost of sodium resources. Among various electrode materials, mixed metal sulfides (MMSs) stand out as promising negative electrode materials for SIBs considering their superior structural and compositional advantages, such as decent electrochemical reversibility, high electronic conductivity, and rich redox reactions. Here, a summary of some recent developments in the rational design and synthesis of various kinds of MMSs with tailorable architectures, structural/compositional complexity, controllable morphologies, and enhanced electrochemical properties is presented. The effect of structural engineering and compositional design of MMSs on the sodium storage properties is highlighted. It is anticipated that further innovative works on the material design of advanced electrodes for batteries can be inspired.

Recent Advances on Mixed Metal Sulfides for Advanced Sodium-Ion Batteries.

Nickle sulfides as promising anode materials for sodium-ion batteries have attracted tremendous attention owing to their large specific capacity and good electrical conductivity. However, the relative large volume changes during the sodiation/desodiation process usually result in a fast capacity decay, poor cycling stability, and sluggish electrode kinetics which hinder their practical applications. Herein, NiS1.03 porous hollow spheres (NiS1.03 PHSs) and porous NiS1.03 hollow cages (NiS1.03 PHCs) with high yield are designed and selectively fabricated via a simple solvothermal and subsequent annealing approach. The obtained NiS1.03 PHSs display long-term cycling stability (127 mAh g-1 after 6000 cycles at 8 A g-1) and excellent rate performance (605 mAh g-1 at 1 A g-1 and 175 mAh g-1 at 15 A g-1). NiS1.03 PHCs also show high rate capability and outstanding cycling stability. In addition, the analyses results of in situ and ex situ XRD patterns and HRTEM images reveal the reversible Na-ion conversion mechanism of NiS1.03. It is also worth noting that the NiS1.03 PHSs//FeFe(CN)6 full cell is successfully assembled and exhibits an initial reversible capacity of 460 mAh g-1 at 0.5 A g-1, which further evidence that NiS1.03 is a kind of prospective anode material for SIBs.

Fang Tian

Papers

NiS1.03 Hollow Spheres and Cages as Superhigh Rate Capacity and Stable Anode Materials for Half/Full Sodium-Ion Batteries.

Rational fabrication of CoS2/Co4S3@N-doped carbon microspheres as excellent cycling performance anode for half/full sodium ion batteries

SnP2O7 Covered Carbon Nanosheets as a Long-Life and High-Rate Anode Material for Sodium-Ion Batteries

Mesoporous Cu2-xSe nanocrystals as an ultrahigh-rate and long-lifespan anode material for sodium-ion batteries

Uniform nucleation of sodium in 3D carbon nanotube framework via oxygen doping for long-life and efficient Na metal anodes