Sodium ion batteries (SIBs) have been considered a promising alternative to lithium ion batteries for large-scale energy storage. However, their inferior electrochemical performances, especially cyclability, become the major challenge for further development of SIBs. Large volume change and sluggish diffusion kinetics are generally considered to be responsible for the fast capacity degradation. Here we report the strong chemical bonding of nanostructured SbS on sulfur-doped graphene sheets (SbS/SGS) that enables a stable capacity retention of 83% for 900 cycles with high capacities and excellent rate performances. To the best of our knowledge, the cycling performance of the SbS/SGS composite is superior to those reported for any other Sb-based materials for SIBs. Computational calculations demonstrate that sulfur-doped graphene (SGS) has a stronger affinity for SbS and the discharge products than pure graphene, resulting in a robust composite architecture for outstanding cycling stability. Our study shows a feasible and effective way to solve the long-term cycling stability issue for SIBs.

Sodium ion batteries (SIBs) are a promising alternative to lithium ion batteries for a broader range of energy storage applications in the future. However, the development of high-performance anode materials is a bottleneck of SIBs advancement. In this work, Sb 2 Se 3 nanorods uniformly wrapped by reduced graphene oxide (rGO) as a promising anode material for SIBs are reported. The results show that such Sb 2 Se 3 /rGO hybrid anode yields a high reversible mass-specific energy capacity of 682, 448, and 386 mAh g −1 at a rate of 0.1, 1.0, and 2.0 A g −1 , respectively, and sustains at least 500 stable cycles at a rate of 1.0 A g −1 with an average mass-specific energy capacity of 417 mAh g −1 and capacity retention of 90.2%. In situ X-ray diffraction study on a live SIB cell reveals that the observed high performance is a result of the combined Na + intercalation, conversion reaction between Na + and Se, and alloying reaction between Na + and Sb. The presence of rGO also plays a key role in achieving high rate capacity and cycle stability by providing good electrical conductivity, tolerant accommodation to volume change, and strong electron interactions to the base Sb 2 Se 3 anode.

Molybdenum disulfide (MoS 2 ) has been considered to be a promising anode material for sodium ion batteries (SIBs), because of its high capacity and graphene-like layered structure. However, irreversible conversion reaction during the sodiation/desodiation process is a major problem that must be overcome before its practical applications. In this work, MoS 2 /amorphous carbon (C) microtubes (MTs) composed of heterostructured MoS 2 /C nanosheets have been developed via a simple template method. The existence of MoS 2 /C heterointerface plays a key role in achieving high and stable performance by stabilizing the reaction products Mo and sulfide phases, providing fast electronic and Na + ions diffusion mobility, and alleviating the volume change. MoS 2 /C MTs exhibit a high reversible specific capacity of 563.5 mA h g −1 at 0.2 A g −1 , good rate performance (520.5, 489.4, 452.9, 425.1, and 401.3 mA h g −1 at 0.5, 1.0, 2.0, 5.0, and 10.0 A g −1 , respectively), and excellent cycling stability (484.9 mA h g −1 at 2.0 A g −1 after 1500 cycles).

Here we report chemically-exfoliated V5S8 and graphite hybrid nanosheets (ce-V5S8–C) as a novel anode material for sodium-ion batteries (SIBs).

Lithium-rich layered oxides are promising cathode materials for lithium-ion batteries and exhibit a high reversible capacity exceeding 250 mAh g(-1) . However, voltage fade is the major problem that needs to be overcome before they can find practical applications. Here, Li1.2 Mn0.54 Ni0.13 Co0.13 O2 (LLMO) oxides are subjected to nanoscale LiFePO4 (LFP) surface modification. The resulting materials combine the advantages of both bulk doping and surface coating as the LLMO crystal structure is stabilized through cationic doping, and the LLMO cathode materials are protected from corrosion induced by organic electrolytes. An LLMO cathode modified with 5 wt % LFP (LLMO-LFP5) demonstrated suppressed voltage fade and a discharge capacity of 282.8 mAh g(-1) at 0.1 C with a capacity retention of 98.1 % after 120 cycles. Moreover, the nanoscale LFP layers incorporated into the LLMO surfaces can effectively maintain the lithium-ion and charge transport channels, and the LLMO-LFP5 cathode demonstrated an excellent rate capacity.

SnS 2 has been extensive studied as an anode material for sodium storage owing to its high theoretical specific capacity, whereas the unsatisfied initial Coulombic efficiency (ICE) caused by the partial irreversible conversion reaction during the charge/discharge process is one of the critical issues that hamper its practical applications. Hence, heterostructured SnS 2 /Mn 2 SnS 4 /carbon nanoboxes (SMS/C NBs) have been developed by a facial wet-chemical method and utilized as the anode material of sodium ion batteries. SMS/C NBs can deliver an initial capacity of 841.2 mAh g −1 with high ICE of 90.8%, excellent rate capability (752.3, 604.7, 570.1, 546.9, 519.7, and 488.7 mAh g −1 at the current rate of 0.1, 0.5, 1.0, 2.0, 5.0, and 10.0 A g −1 , respectively), and long cycling stability (522.5 mAh g −1 at 5.0 A g −1 after 500 cycles). The existence of SnS 2 /Mn 2 SnS 4 heterojunctions can effectively stabilize the reaction products Sn and Na 2 S, greatly prevent the coarsening of nanosized Sn 0 , and enhance reversible conversion−alloying reaction, which play a key role in improving the ICE and extending the cycling performance. Moreover, the heterostructured SMS coupled with the interacting carbon network provides efficient channels for electrons and Na + diffusion, resulting in an excellent rate performance.

Heterostructuring electrodes with multiple electroactive and inactive supporting components to simultaneously satisfy electrochemical and structural requirements has recently been identified as a viable pathway to achieve high-capacity and durable sodium-ion batteries (SIBs). Here, a new design of heterostructured SIB anode is reported consisting of double metal-sulfide (SnCo)S 2 nanocubes interlaced with 2D sulfur-doped graphene (SG) nanosheets. The heterostructured (SnCo)S 2 /SG nanocubes exhibit an excellent rate capability (469 mAh g −1 at 10.0 A g −1 ) and durability (5000 cycles, 487 mAh g −1 at 5.0 A g −1 , 92.6% capacity retention). In situ X-ray diffraction reveals that the (SnCo)S 2 /SG anode undergoes a six-stage Na + storage mechanism of combined intercalation, conversion, and alloying reactions. The first-principle density functional theory calculations suggest high concentration of p-n heterojunctions at SnS 2 /CoS 2 interfaces responsible for the high rate performance, while in situ transmission electron microscopy unveils that the interlacing and elastic SG nanosheets play a key role in extending the cycle life.

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