Industrially prepared artificial graphite (AG) is attractive for potassium-ion batteries (PIBs), but its rate performance is poor and the production process is energy intensive, so developing an efficient strategy to produce novel graphite with low energy consumption and high performance is economically important. Herein, a nanostructured graphite composed of multi-walled carbon nanotubes (MWCNTs) and graphite shells was prepared by one-pot method through low-temperature pyrolysis of iron-based metal-organic framework (MOF) and carbon source. The high graphitization degree of nanostructured graphite makes the initial Coulombic efficiency (ICE) exceed 80%, and the three-dimensional (3D) conductive network ensures a specific capacity of 234 mAh·g⁻¹ after 1000 cycles at a high current density of 500 mA·g⁻¹. In addition, the typical graphite potassium storage mechanism is also demonstrated by in situ X-ray diffraction (XRD) and in situ Raman spectroscopy, and its practicality is also proved by the voltage of the full cells. This work provides a feasible way to optimize the practical production process of AG and expand its application in energy storage.

Bismuth has garnered significant interest as an anode material for magnesium batteries (MBs) because of its high volumetric specific capacity and low working potential. Nonetheless, the limited cycling performance (≤100 cycles) limits the practical application of Bi as anode for MBs. Therefore, the improvement of Bi cycling performance is of great significance to the development of MBs and is also full of challenges. Here, Bi nanoparticles encapsulated in nitrogen-doped carbon with single-atom Bi embedded (Bi@NC) are prepared and reported as an anode material for MBs. Bi@NC demonstrates impressive performance, with a high discharge capacity of 347.5 mAh g⁻¹ and good rate capability (206.4 mAh g⁻¹@500 mA g⁻¹) in a fluoride alkyl magnesium salt electrolyte. In addition, Bi@NC exhibits exceptional long-term stability, enduring 400 cycles at 500 mA g⁻¹. To the best of our knowledge, among reported Bi and Bi-based compounds for MBs, Bi@NC exhibits the longest cycle life in this work. The magnesium storage mechanism of Bi@NC is deeply studied through X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. This work provides some guidance for further improving the cycling performance of other alloy anodes in MBs.

The development and application of high performance potassium ion batteries (PIBs) is a major demand for China's strategic emerging industries, and it is also a new system and direction for the development of energy storage secondary batteries. However, the current research on PIBs is still in its initial stage, and still faces the challenges of slow diffusion kinetics, unclear transport mechanism, rapid capacity decay and difficulty in revealing the intrinsic decay mechanism. This paper summarizes the latest research results of the National Natural Science Foundation of China (NSFC) project "Surface/Interface Tuning and In Situ Interaction Mechanism of Hierarchical Mesoporous Nanowire Cathodes for Potassium Ion Battery", systematically describes the key scientific problems and technical bottlenecks in PIB research, and points out the efficient strategies to solve these problems and bottlenecks.

Aqueous zinc ion batteries (AZIBs) are ideal candidates for large-scale battery storage, with a high theoretical specific capacity, ecological friendliness, and extremely low cost but are strongly hindered by zinc dendrite growth. Herein, Ni-Zn alloy is artificially constructed as a solid-electrolyte interface (SEI) for Zn anodes by electrodeposition and annealing. The Ni-Zn alloy layer acts as a dynamic shield at the electrode/electrolyte interface. Interestingly, the zinc atoms migrate out of the electrode body during zinc stripping while merging into the electrode body during the plating. In this way, the Ni-Zn alloy is able to guide the zinc deposition in the horizontal direction, thereby suppressing the formation of dendrite. Benefiting from those, the Ni-Zn alloy symmetric cell shows a greatly improved cycle life and is able to operate stably for 1,900 h at a current density of 0.5 mA·cm⁻². The present study is a strategy for negative electrode protection of AZIBs.

The Fe–N–C material represents an attractive oxygen reduction reaction electrocatalyst, and the FeN₄ moiety has been identified as a very competitive catalytic active site. Fine tuning of the coordination structure of FeN₄ has an essential impact on the catalytic performance. Herein, we construct a sulfur-modified Fe–N–C catalyst with controllable local coordination environment, where the Fe is coordinated with four in-plane N and an axial external S. The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN₄ active site. The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons. With the above characteristics, the adsorption and desorption of the reactants at FeN₄ active sites are optimized, thus promoting the oxygen reduction reaction activity. This work explores the key point in electronic configuration and coordination environment tuning of FeN₄ through S doping and provides new insight into the construction of M–N–C-based oxygen reduction reaction catalysts.

Advances in electrochemical energy storage technologies drive the need for battery safety performance and miniaturization, which calls for the easily processable polymer electrolytes suitable for on-chip microbattery technology. However, the low ionic conductivity of polymer electrolytes and poor-patternable capabilities hinder their application in microdevices. Herein, we modified SU-8, as the matrix material, by poly(ethylene oxide) (PEO) with lithium salts to obtain a patternable lithium-ion polymer electrolyte. Due to the highly amorphous state and more Li-ion transport pathways through blending effect and the increase in number of epoxides, the ionic conductivity of achieved sample is increased by an order of magnitude to 2.9 × 10⁻⁴ S·cm⁻¹ in comparison with the SU-8 sample at 50 °C. The modified SU-8 exhibits good thermal stability (> 150 °C), mechanical properties (elastic modulus of 1.52 GPa), as well as an electrochemical window of 4.3 V. Half-cell and microdevice were fabricated and tested to verify the possibility of the micro-sized on-chip battery. All of these results demonstrate a promising strategy for the integration of on-chip batteries with microelectronics.

Attributing to the high specific capacity and low electrochemical reduction potential, lithium (Li) metal is regarded as the most promising anode for high-energy Li batteries. However, the growth of lithium dendrites and huge volume change seriously limit the development of lithium metal batteries. To overcome these challenges, an ordered mesoporous N-doped carbon with lithiophilic single atoms is proposed to induce uniform nucleation and deposition of Li metal. Benefiting from the synergistic effects of interconnected three-dimensional ordered mesoporous structures and abundant lithiophilic single-atom sites, regulated local current density and rapid mass transfer can be achieved, leading to the uniform Li deposition with inhibition of dendrites and buffered volume expansion. As a result, the as-fabricated anode exhibits a high CE of 99.8% for 200 cycles. A stable voltage hysteresis of 14 mV at 5 mA cm⁻² could be maintained for more than 1330 h in the symmetric cell. Furthermore, the full cell coupled with commercial LiFePO₄ exhibits high reversible capacity of 108 mAh g⁻¹ and average Coulombic efficiency of 99.8% from 5th to 350th cycles at 1 C. The ordered mesoporous carbon host with abundant lithiophilic single-atom sites delivers new inspirations into rational design of high-performance Li metal anodes.

Aqueous zinc ion batteries have been considered as the prominent candidate in the next-generation batteries for its low cost, safety and high theoretical capacity. Nonetheless, formation of zinc dendrites and side reactions at the electrode/electrolyte interface during the zinc plating/stripping process affect the cycling reversibility of the zinc anode. Regulation of the zinc plating/ stripping process and realizing a highly reversible zinc anode is a great challenge. Herein, we applied a simple and effective approach of controlled-current zinc pre-deposition at copper mesh. At the current density of 40 mA cm⁻², where the electron/ion transfers are both continuous and balanced, the Zn@CM-40 electrode with the (002) crystal plane orientation and the compactly aligned platelet morphology was successfully obtained. Compared with the zinc foil, the Zn@CM-40 exhibits greatly enhanced reversibility in the repeated plating/stripping (850 h at 1 mA cm⁻²) for the symmetric battery test. A series of characterization techniques including electrochemical analyses, XRD, SEM and optical microscopy observation, were used to demonstrate the correlation between the structure of pre-deposited zinc layer and the cycling stability. The COSMOL Multiphysics modeling demonstrates a more uniform electric field distribution in the Zn@CM than the zinc foil due to the aligned platelet morphology. Furthermore, the significant improvement is also achieved in a Zn||MnO₂ full battery with a high capacity-retention (87% vs 47.8%). This study demonstrates that controlled-current electrodeposition represents an important strategy to regulate the crystal plane orientation and the morphology of the pre-deposited zinc layer, hence leading to the highly reversible and dendrite-free zinc anode for high-performance zinc ion batteries.

Rational design and construction of highly efficient nonprecious electrocatalysts for oxygen reduction and alcohols oxidation reactions (ORR, AOR) are extremely vital for the development of direct oxidation alkaline fuel cells, metal-air batteries, and water electrolysis system involving hydrogen and value-added organic products generation, but they remain a great challenge. Herein, a bifunctional electrocatalyst is prepared by anchoring CuS/NiS₂ nanoparticles with abundant heterointerfaces and sulfur vacancies on graphene (Cu₁Ni₂-S/G) for ORR and AOR. Benefiting from the synergistic effects between strong interfacial coupling and regulation of the sulfur vacancies, Cu₁Ni₂-S/G achieves dramatically enhanced ORR activity with long term stability. Meanwhile, when ethanol is utilized as an oxidant for AOR, an ultralow potential (1.37 V) at a current density of 10 mA cm⁻² is achieved, simultaneously delivering a high Faradaic efficiency of 96% for ethyl acetate production. Cu₁Ni₂-S/G also exhibits catalytic activity for other alcohols electrooxidation process, indicating its multifunctionality. This work not only highlights a viable strategy for tailoring catalytic activity through the synergetic combination of interfacial and vacancies engineering, but also opens up new avenues for the construction of a self-driven biomass electrocatalysis system for the generation of value-added organic products and hydrogen under ambient conditions.

Developing efficient oxygen reduction reaction (ORR) catalyst is essential for the practical application of Zn-air batteries (ZABs). In this contribution, we develop a novel zeolitic imidazolate framework (ZIF)-mediated strategy to anchor Co species on N-doped carbon nanorods for efficient ORR. Featuring ultrahigh N-doping (10.29 at.%), monodisperse Co nanocrystal decoration, and well-dispersed Co-N_x functionalization, the obtained Co-decorated N-doped carbon nanorods (Co@NCNR) exhibit a decent ORR performance comparable to commercial Pt/C in alkaline media. Aqueous ZABs have been assembled using Co@NCNR as the cathode catalyst. The assembled ZABs manifest high initial open-circuit voltage as well as high energy density. In addition, the Co@NCNR also demonstrates ideal ORR performance in quasi-solid-state ZABs.