A New Strategy for Maximizing the Storage Capacity of Lithium in Carbon Materials

Introducing micropores into carbon nanoparticles synthesized via a solution plasma process by thermal treatment and their charge storage properties in supercapacitors

Carbon materials synthesized via a solution plasma process (SPP) have recently shown great potential for various applications. However, they mainly possess a meso-macroporous structure with a lack of micropores, which limits their applications for supercapacitors. Herein, carbon nanoparticles (CNPs) were synthesized from benzene via SPP and then subjected to thermal treatment at different temperatures (400, 600, 800, and 1000 °C) in an argon environment. The CNPs exhibited an amorphous phase and were more graphitized at high treatment temperatures. A small content of tungsten carbide particles was also observed, which were encapsulated in CNPs. An increase in treatment temperature led to an increase in the specific surface area of CNPs from 184 to 260 m² g^-1 through the development of micropores, while their meso-macropore structure remained unchanged. The oxygen content of CNPs decreased from 14.72 to 1.20 atom% as the treatment temperature increased due to the degradation of oxygen functionality. The charge storage properties of CNPs were evaluated for supercapacitor applications by electrochemical measurements using a three-electrode system in 1 M H₂SO₄ electrolyte. The CNPs treated at low temperatures exhibited an electric double layer and pseudocapacitive behavior due to the presence of quinone groups on the carbon surface. With increasing treatment temperature, the electric double layer behavior became more dominant, while pseudocapacitive behavior was suppressed due to the quinone degradation. Regarding cycling stability, the CNPs treated at high temperatures (with a lack of oxygen functionality) were more stable than those treated at low temperatures. This work highlights a way of introducing micropores into CNPs derived from SPP via thermal treatment, which could be helpful for controlling and adjusting their pore structure for supercapacitor applications.

S and P Dual-Doped Carbon Nanospheres as Anode Material for High Rate Performance Sodium-Ion Batteries

The heteroatom doping of carbon materials can significantly improve the electrochemical performance of sodium-ion batteries. However, conventional doping techniques involve more than two steps, making them unsuitable for scale-up. In this study, an S and P co-doped carbon material is synthesized using a simple, one-step plasma-in-liquid process. The synthesized material consists of abundant macropores, which can improve the electrochemical properties of sodium-ion batteries. When the synthesized anode material is applied to a sodium-ion half-cell, the cell exhibits a remarkable cycling life of 3000 cycles at a high current density of 10 A g−1, with a high reversible capacity over 125 mAh g−1. These results indicate that S and P co-doped carbon materials are promising candidates as anodes for sodium-ion batteries, and the plasma-in-liquid process is an effective strategy for heteroatom co-doping.

The structure-directing role of graphene in composites with porous FeOOH nanorods for Li ion batteries

Graphene sheets that contain porous iron oxides including Fe2O3 and FeOOH nanorods were synthesized via a one-step hydrothermal route. A novel mechanism for controlling the structure of graphene-based composites was developed. Porous FeOOH nanorods with a high capacity for electron- and ion-transport were synthesized by controlling the composition of GO dispersion. The synthesized graphene/FeOOH composite anode exhibited an excellent electrochemical performance in which a reversible capacity of 304 mA h g-1 was reached with nearly 100% coulombic efficiency after 1000 cycles of charge and discharge under a high current rate of 5 A g-1.

Novel Approach Through the Harmonized Sulfur in Disordered Carbon Structure for High-Efficiency Sodium-Ion Exchange

Sodium-ion batteries (SiBs) have recently attracted considerable interest due to the plentiful supply of raw materials for their production and their electrochemical behavior, which is similar to that of lithium-ion batteries (LiBs). However, the relatively larger radius of sodium ions than that of lithium ions is not suitable for storage in conventional graphite, which is widely used as the anode. To resolve this issue, in this study, we developed a new harmonized carbon material with a three-dimensional (3D) grapevine-like structure and a sulfur component using an efficient synthesis process. On the basis of these advantages, the harmonized sulfur-carbon material exhibited a highly reversible capacity of 146 mA h g^-1 at an extremely high specific current of 100 A g^-1 and long-term galvanostatic cycling stability at 10 and 100 A g^-1 with superior electrochemical performance. Our results are anticipated to provide new insights into SiB anode materials that would advance their production.

Tuning wettability of molten lithium via a chemical strategy for lithium metal anodes

Metallic lithium affords the highest theoretical capacity and lowest electrochemical potential and is viewed as a leading contender as an anode for high-energy-density rechargeable batteries. However, the poor wettability of molten lithium does not allow it to spread across the surface of lithiophobic substrates, hindering the production and application of this anode. Here we report a general chemical strategy to overcome this dilemma by reacting molten lithium with functional organic coatings or elemental additives. The Gibbs formation energy and newly formed chemical bonds are found to be the governing factor for the wetting behavior. As a result of the improved wettability, a series of ultrathin lithium of 10–20 μm thick is obtained together with impressive electrochemical performance in lithium metal batteries. These findings provide an overall guide for tuning the wettability of molten lithium and offer an affordable strategy for the large-scale production of ultrathin lithium, and could be further extended to other alkali metals, such as sodium and potassium.

Molten lithium cannot spread onto the lithiophobic substrate, hindering the production and application of lithium metal anodes. Here, the authors show a general chemical strategy to tune the wettability by forming new chemical bonds through the reactions with various organic coatings or elemental additives.

Materials by Design: Tailored Morphology and Structures of Carbon Anodes for Enhanced Battery Safety

Next-generation Li-ion battery technology awaits materials that not only store more electrochemical energy at finite rates but also exhibit superior control over side reactions and better thermal stability. Herein, we hypothesize that designing an appropriate particle morphology can provide a well-balanced set of physicochemical interactions. Given the anode-centric nature of primary degradation modes, we investigate three different carbon particles-commercial graphite, spherical carbon, and spiky carbon-and analyze the correlation between particle geometry and functionality. Intercalation dynamics, side reaction rates, self-heating, and thermal abuse behavior have been studied. It is revealed that the spherical particle outperforms an irregular one (commercial graphite) under thermal abuse conditions, as it eliminates unstructured inhomogeneities. A spiky particle with ordered protrusions exhibits smaller intercalation resistance and attenuated side reactions, thus outlining the benefits of controlled stochasticity. Such findings emphasize the importance of tailoring particle morphology to proffer selectivity among multimodal interactions.