Rechargeable magnesium-metal batteries (RMBs) have gained much attention due to their abundant resources as well as high safety. However, the high charge density of Mg²⁺ is one of the main reasons for the slow kinetics performance of RMBs, and modulation of the charge density is an important strategy to improve the kinetics and electrochemical performance of RMBs. Herein, we report on the conductive polymer polyaniline (PANI) for RMBs, which is found to have excellent kinetics and high discharge voltage when storing MgCl⁺. In the storage of MgCl⁺, PANI exhibits a high average discharge voltage platform is 2.3 V vs. Mg²⁺/Mg, which is higher than that in storage of Mg²⁺. We demonstrated the reversible intercalation/de-intercalation of MgCl⁺ in PANI accompanying with the reversible transformation between the quinone ring (C–C, –N=) and the benzene ring (C=C, –NH–) during charging and discharging. Density functional theory calculation reveals that PANI exhibit higher voltages (2.25 V vs. 1.82 V) along with lower diffusion energy barriers (1.27 eV vs. 1.55 eV) for MgCl⁺ storage compared to Mg²⁺ storage. This work refines the storage mechanism of PANI in RMBs and provides new guidelines for the application of PANI in RMBs.

The separator is of great significance to alleviate the shuttle effect and dendrite growth of lithium-sulfur batteries. However, most of the current commercial separators cannot meet these requirements well. In this work, a dense metal-organic-framework (MOF) modification layer is in-situ prepared by the assistant of polydopamine on the polypropylene separators. Due to the unique structure and synergistic effect of polydopamine (PDA) and zeolitic imidazolate framework-8 (ZIF-8), the functional separator can not only trap the polysulfides effectively but also promote the transport of lithium ions. As a result, the battery assembled with the functional separator exhibits excellent cycle stability. The capacity remains 711 mAh·g⁻¹ after 500 cycles at 2 C, and the capacity decay rate is as low as 0.013% per cycle. The symmetrical battery is cycled for 1,000 h at 2 mA·cm⁻² (2 mAh·cm⁻²) with the plating/stripping overpotential of 20 mV. At the same time, the modification separator shows a higher lithium ion transference number (0.88), better thermal stability and electrolyte wettability than the unmodified separator.

Iron sulfide is an attractive anode material for lithium-ion batteries (LIBs) due to its high specific capacity, environmental benignity, and abundant resources. However, its application is hindered by poor cyclability and rate performance, caused by a large volume variation and low conductivity. Herein, iron sulfide porous nanowires confined in an N-doped carbon matrix (FeS@N-C nanowires) are fabricated through a simple amine-assisted solvothermal reaction and subsequent calcination strategy. The as-obtained FeS@N-C nanowires, as an LIB anode, exhibit ultrahigh reversible capacity, superior rate capability, and long-term cycling performance. In particular, a high specific capacity of 1, 061 mAh·g^-1 can be achieved at 1 A·g^-1 after 500 cycles. Most impressively, it exhibits a high specific capacity of 433 mAh·g^-1 even at 5 A·g^-1. The superior electrochemical performance is ascribed to the synergistic effect of the porous nanowire structure and the conductive N-doped carbon matrix. These results demonstrate that the synergistic strategy of combining porous nanowires with an N-doped carbon matrix holds great potential for energy storage.

Sodium-ion batteries (SIBs) have great promise for sustainable and economical energy-storage applications. Nevertheless, it is a major challenge to develop anode materials with high capacity, high rate capability, and excellent cycling stability for them. In this study, FeSe₂ clusters consisting of nanorods were synthesized by a facile hydrothermal method, and their sodium-storage properties were investigated with different electrolytes. The FeSe₂ clusters delivered high electrochemical performance with an ether-based electrolyte in a voltage range of 0.5–2.9 V. A high discharge capacity of 515 mAh·g^–1 was obtained after 400 cycles at 1 A·g^–1, with a high initial columbic efficiency of 97.4%. Even at an ultrahigh rate of 35 A·g^–1, a specific capacity of 128 mAh·g^–1 was achieved. Using calculations, we revealed that the pseudocapacitance significantly contributed to the sodium-ion storage, especially at high current rates, leading to a high rate capability. The high comprehensive performance of the FeSe₂ clusters makes them a promising anode material for SIBs.