P2-type Na(2/3)Ni(1/3)Mn(2/3)O2 was synthesized by a controlled co-precipitation method followed by a high-temperature solid-state reaction and was used as a cathode material for a sodium-ion battery (SIB). The electrochemical behavior of this layered material was studied and an initial discharge capacity of 151.8 mA h g(-1) was achieved in the voltage range of 1.5-3.75 V versus Na(+)/Na. The retained discharge capacity was found to be 123.5 mA h g(-1) after charging/discharging 50 cycles, approximately 81.4% of the initial discharge capacity. In situ X-ray diffraction analysis was used to investigate the sodium insertion and extraction mechanism and clearly revealed the reversible structural changes of the P2-Na(2/3)Ni(1/3)Mn(2/3)O2 and no emergence of the O2-Ni(1/3)Mn(2/3)O2 phase during the cycling test, which is important for designing stable and high-performance SIB cathode materials.

Well-confined elemental sulfur was implanted into a stacked block of carbon nanospheres and graphene sheets through a simple solution process to create a new type of composite cathode material for lithium-sulfur batteries. Transmission electron microscopy and elemental mapping analysis confirm that the as-prepared composite material consists of graphene-wrapped carbon nanospheres with sulfur uniformly distributed in between, where the carbon nanospheres act as the sulfur carriers. With this structural design, the graphene contributes to direct coverage of sulfur to inhibit the mobility of polysulfides, whereas the carbon nanospheres undertake the role of carrying the sulfur into the carbon network. This composite achieves a high loading of sulfur (64.2 wt %) and gives a stable electrochemical performance with a maximum discharge capacity of 1394 mAh g(-1) at a current rate of 0.1 C as well as excellent rate capability at 1 C and 2 C. The improved electrochemical properties of this composite material are attributed to the dual functions of the carbon components, which effectively restrain the sulfur inside the carbon nano-network for use in lithium-sulfur rechargeable batteries.

The electrolyte additive plays an important role in determining the crucial properties of batteries such as cycling stability and safety. Compared to material development, research on electrolyte and interphase is still in the early stage for sodium ion batteries (SIBs). Herein, for the first time, succinic anhydride (SA) is investigated as a synergistic filming additive to fluoroethylene carbonate (FEC), and the lifespan of the dual‐additive Na/Na0.6Li0.15Ni0.15Mn0.55Cu0.15O2 (NLNMC) cell is significantly improved, maintaining capacity retention of 87.2% over 400 cycles at 1 C rate. For comparison, the batteries with only one of the two additives or without any additive show much inferior electrochemical performance. After the addition of SA, the interphase layer on the surface of cycled NLNMC material becomes uniform and stable, which contains more oxygen‐rich organic species and less NaF. Additionally, the addition of SA also has an impact on the interphase layer in the sodium anode part as indicated by electrochemical impedance spectroscopy (EIS) and energy dispersive spectrometer (EDS) results. Moreover, the online differential electrochemical mass spectrometry (OEMS) tests show the dual‐additive cell has less CO2 generation during the initial two cycles compared to that with only FECs which demonstrates another advantage of SA for practical application.

Lithium (Li) metal is a favorable anode for most energy storage equipment, thanks to its higher theoretical specific capacity. However, nonuniform Li nucleation/growth results in large-sized and irregular dendrites generated from the Li anode, which causes rapid capacity fade and serious safety hazard, hindering its widespread practical applications. In this paper, with the aid of a lithium nitrate (LiNO3) additive in a carbonate-based electrolyte, the Li anode shows low hysteresis for in excess of 1000 h at a current density of 0.5 mA cm–2. At the same time, a Li–graphite dual-ion battery exhibits an outstanding cycling stability at 5C; after 1000 cycles, 81% of the capacity is retained. After calculation, the Li–graphite dual-ion battery shows a competitive specific energy density of 243 Wh kg–1 at a power density of 234 W kg–1. Moreover, the linear sweep voltammetry test was first performed to analyze the Li nucleation/growth mechanism and explain the effect of the LiNO3 additive. The superior electrochemical properties of the Li–graphite dual-ion battery are ascribed to the formation of smooth Li composed of Li nanoparticles and a steady solid electrolyte interface film.

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Nitrogen-doped hollow carbon nanospheres (NHCSs) were prepared by a facile template method with dopamine as the precursor and subsequently used as the anode material for sodium-ion batteries. The N-HCSs demonstrated high reversible capacities with a retained capacity of 162.2 mA h g -1 over 100 cycles at 0.1 A g -1 and an excellent rate capability with an attainable capacity of 90 mA h g -1 at a high current density of 5 A g -1. Detailed characterization re-

Copper containing composites have been widely investigated among various sodium layered cathode materials due to the low cost and abundance of copper element. However, the electrochemical performance of these composites...

Figure 4. The cross-sectional SEM images of PAA/mSi and Am-PAA/mSi electrodes(a, b) beforeand (c, d) after cycling stability test.