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As the most promising anodic candidate for alkali ion batteries, red phosphorus (P) still faces big challenges, such as the poor rate and cycling performance, which are caused by the insulative nature and the large volume change throughout the alloy/dealloy process. To ameliorate above issues, the traditional way is confining P into the carbon host. However, investigations on maximizing P utilization are inadequate; in other words, how to achieve entire confinement with a high loading amount is still a problem. Additionally, the application of P in potassium-ion batteries (PIBs) is in its infant stage, and the corresponding potassiation product is controversial. Herein, a nitrogen-doped stripped-graphene CNT (N-SGCNT) as carbon framework is prepared to exclusively confine ultrafine P to construct P@N-SGCNT composites. Benefitting from the in situ cross-linked structure, N-SGCNT loaded with 41.2 wt % P (P2@N-SGCNT) shows outstanding Na+/K+ storage performance. For instance, P2@N-SGCNT exhibits high reversible capacities of 2480 mAh g-1 for sodium-ion batteries (SIBs) and 762 mAh g-1 for PIBs, excellent rate capabilities of 1770 mAh g-1 for SIBs and 354 mAh g-1 for PIBs at 2.0 A g-1, and long cycling stability (a capacity of 1936 mAh g-1 after 2000 cycles for SIBs and 319 mAh g-1 after 1000 cycles for PIBs). Furthermore, due to this exclusively confined P structure, the K+ storage mechanism with the end product of K4P3 has been identified by experimental and theoretical results.

Magnesium-based hydrides are promising hydrogen storage materials; however, little progress has been achieved in improving hydrogen storage performance under ambient conditions, consequently impeding further commercial application. Herein, a lithium rich transition metal oxide, Li3VO4 has been employed to catalyze the hydrogen storage reaction of magnesium-based hydrides, enabling a fast and full hydrogenation of Mg at lower temperatures. The structural stability of Li3VO4 upon de/rehydrogenation reactions has been confirmed by neutron diffraction and transmission electron microscope observations. The synergistic catalytic role of Li3VO4 has elucidated that the existence of Li stimulates the catalytic activity of V and simultaneously suppresses the activity of O. V is the key catalytically active site, while O can react with active Mg to generate MgO which is a passivation layer and could prevent the diffusion of H. These findings will give an opportunity for the use of other lithium rich transition metal oxides in the field of catalyzing hydrogen storage systems.

The hexagonal sheet shaped Fe3O4/Fe7S8 heterojunction with lateral size of 1.5 μm has been controllably synthesized by gas sulfuration process. The most fascinating performance of this Fe3O4/Fe7S8 heterojunction structure is that the capacity attenuation is rather small of only 18%, from 818 mAh·g−1 to 670 mAh·g−1, when the current density increases ten-fold from 0.2 A·g−1 to 2.0 A·g−1. This high capacity retention upon current density shifting, is attributed to pseudocapacitance contribution, which is related to the two-dimensional hexagonal structure, faster electron/ion transfer and synergistic effect for the stepwise lithiation of Fe3O4 and Fe7S8 at different voltage in Fe3O4/Fe7S8 heterojunction. This rational design on heterojunction structure sheds light on further constructing novel anode material for secondary ion batteries.

A three-dimensional porous copper film is directly deposited on Cu foam by an electrodeposition method using hydrogen bubbles as dynamic template (denoted as Cu/Cu foam). Its electrocatalytic activity toward hydrazine electrooxidation is tested by linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Compared with Cu foam, hydrazine electrooxidation on the Cu/Cu foam electrode shows that the onset oxidation potential displays a ~100 mV negative shift, the current density at −0.6 V raises about 14 times, the apparent activation energy and the charge transfer resistance reduce significantly. The increasing electrocatalytic performance for hydrazine electrooxidation is mainly caused by the highly porous structure of the Cu/Cu foam electrode which can provide a large surface area and make electrolyte access the electrocatalyst surfaces more easily. Hydrazine electrooxidation on the Cu/Cu foam electrode proceeds through a near 4-electron process.

Germanium-based materials possess high theoretical capacity of approximately 1000 mAh·g−1, nevertheless, the practical electrochemical performance is severely hampered by poor cyclability due to volumetric expansion of Ge upon cycling. Herein, novel hydrangea-like CoGeO2(OH)2 constructed by 2D nanoplates has been facilely synthesized with the assistance of ethylene glycol and further applied to anode materials for lithium ion storage. The hydrangea-like CoGeO2(OH)2 anode exhibits an enhanced specific capacity of 1174 mAh·g−1 at a current density of 0.5 A g−1 after 100 cycles. Such outstanding electrochemical performance could be accredited to the rationally designed hydrangea-like structure, which can relieve the interval stress aroused by lithiation/de-lithiation, shorten the pathway of electron/ion transportation and take advantage of the pseudocapacitive nature of two dimensional nanosheets that could improve the reaction kinetics and endow the material with remarkable rate capability. Moreover, the inherent Co-bonded hydroxyl groups facilitate the pseudocapacitive effect, and Ge-based component contributes to the capacity. These advantages help CoGeO2(OH)2 hydrangeas gain a competitive edge over other candidates of anode materials for lithium-ion batteries.