Metal-ion hybrid capacitors, such as potassium-ion hybrid capacitors (PIHCs), are regarded as promising fast-charging energy storage devices. However, the kinetics mismatch between the battery anode and the capacitive cathode restricts their fast-charging performance. Precisely constructing carbon anodes with enhanced kinetics is an innovative approach to address this challenge. Herein, using epigallocatechin gallate with high oxygen content as the precursor, oxygen-enriched carbon materials (OEC) with tunable C=O content are successfully synthesized. Effortlessly, the C=O content of OEC is regulated by adjusting the pyrolysis temperature. Serving as an anode for PIHCs, OEC-600 with the highest C=O content exhibits an attractive fast-charging specific capacity of 135.2 mAh·g⁻¹ at 20 A·g⁻¹, along with a superior fast-charging cycling stability. Combining theoretical calculations, comprehensive kinetics analysis and in-situ Raman, the positive effects of C=O on the potassium storage capability and reversibility of OEC-600 are revealed. Consequently, PIHCs assembled based on an OEC-600 anode deliver impressive energy/power density of 145.1 Wh·kg⁻¹/45.9 kW·kg⁻¹ and superior fast-charging cycling stability with 87.5% of capacity retention over 20,000 cycles at 5 A·g⁻¹. This work is anticipated to provide an optional design concept toward the carbon anode for fast-charging PIHCs.

NASICON-structured Na₃Zr₂Si₂PO₁₂ (NZSP) has been considered as one of the ideal electrolytes for all-solid-state sodium metal batteries (ASSSB). However, the practical application of NZSP-based ASSSB is hindered by the low ionic conductivity and large interfacial resistance caused by the poor contact between NZSP and Na metal. Herein, the introduction of Fe₂O₃ not only improves ionic conductivity and reduces activation energy by the doping of Fe³⁺ in the crystal structure of NZSP, but also reduces the interfacial resistance and enhances interface stability between NZSP and Na metal anode. The synergistic effects significantly enhance the cycling stability, rate capability, and critical current density of the symmetrical solid-state cells. The interfacial reaction mechanism indicates that Fe³⁺ in the interface is reduced Fe²⁺ by Na anode, which effectively even the electric-filed distribution and suppresses the dendrite growth. Consequently, the symmetric solid-state cells exhibit stable cycling performance for 1,500 h at 0.1 mA·cm⁻¹/0.1 mA·h·cm⁻¹ and over 900 h at 0.2 mA·cm⁻¹/0.2 mA·h·cm⁻¹. The Na|NZSP-0.075%Fe₂O₃|Na₂FePO₄F solid-state full cells display high capacity retention of 94.2% after 100 cycles at 0.5 C. The stable interface of NZSP/Na and improved ionic conductivity contribute to excellent electrochemical performance, which accelerates the practical application of ASSSB.

Tin-based oxides and their alloys with high specific capacities are considered as promising anode materials for Na-ion batteries. However, the tin-based oxides and their alloys suffer from a large volume variation and particle agglomeration during the charge-discharge process, resulting in electrode pulverization, capacity fading, and poor rate performance. In this paper, Bi/SnO_x particles anchored on an ultrathin carbon layer (Bi/SnO_x@C) were synthesized by a sodium chloride template method, and a uniform Bi/SnO_x@C heterostructure is constructed. The ultrathin carbon layer can effectively inhibit the agglomeration of Bi/SnO_x particles and increase the specific surface area of the electrode material, providing more active sites. Bi/SnO_x can also contribute the more specific capacity. The synergistic effect of ultrathin carbon layer and Bi/SnO_x composite can effectively improve the cycling stability, which is of great significance for the construction of high-performance electrode materials.

Anthracite has a great application potential in energy storage because of its low cost, but the reversible capacity of raw anthracite as an anode material for the sodium-ion battery is rather low. In this paper, anthracite was pyrolyzed at different temperatures. The results show that the reversible capacity of anthracite pyrolyzed at 1300 ℃ (A-1300) is 307 mA·h/g at 20 mA/g, which is the maximum value among the pyrolyzed anthracites. However, the reversible capacity of A-1300 at 500 mA/g is only 105 mA·h/g, exhibiting an inferior rate performance. The two-step strategy via hydrogenation and pyrolysis can decrease the pyrolyzed temperature and improve the rate performance. Hydrogenated anthracite turns into an easy-graphitized precursor. The reversible capacity of hydrogenated anthracite pyrolyzed at 900 ℃ (H300-3-900) can retain 113 mA·h/g at 500 mA/g after 500 cycles, exhibiting a superior rate performance and an easier commercial production at a lower temperature.

Fe_xMo_1–xS₂ with an expanded interlayer spacing of 0.75 nm was prepared via a simple solvothermal method. The larger interlayer spacing enhances the rate of Na⁺ diffusion during initial cycle. Fe_xMo_1–xS₂ as an anode for sodium ion batteries exhibits a high capacity of 285 m A·h/g at 0.1 A/g after 100 cycles and an excellent rate capability of 178 m A·h/g at 5 A/g. The fresh and cycled electrodes were characterized by in-situ X-ray photoelectric spectroscopy and transmission electronic microscopy to investigate electrochemical reaction mechanism of Fe_xMo_1–xS₂ during cycling. The results indicate that the irreversible conversion reaction of Fe_xMo_1–xS₂ with Na⁺ results in the formation of main products of Fe–Mo alloy and S.