Revisiting the Roles of Natural Graphite in Ongoing Lithium-Ion Batteries

Graphite, commonly including artificial graphite and natural graphite (NG), possesses a relatively high theoretical capacity of 372 mA h g^-1 and appropriate lithiation/de-lithiation potential, and has been extensively used as the anode of lithium-ion batteries (LIBs). With the requirements of reducing CO₂ emission to achieve carbon neutral, the market share of NG anode will continue to grow due to its excellent processability and low production energy consumption. NG, which is abundant in China, can be divided into flake graphite (FG) and microcrystalline graphite (MG). In the past 30 years, many researchers have focused on developing modified NG and its derivatives with superior electrochemical performance, promoting their wide applications in LIBs. Here, a comprehensive overview of the origin, roles, and research progress of NG-based materials in ongoing LIBs is provided, including their structure, properties, electrochemical performance, modification methods, derivatives, composites, and applications, especially the strategies to improve their high-rate and low-temperature charging performance. Prospects regarding the development orientation as well as future applications of NG-based materials are also considered, which will provide significant guidance for the current and future research of high-energy-density LIBs.

DFT and experimental study of nano red phosphorus anchoring on sulfurized polyacrylonitrile for lithium-ion batteries

Sulfur atoms can reconstruct the configuration of PAN, which makes the electron transfer more convenient and reduces the energy barriers during Li ion diffusion. The sulfurized polyacrylonitrile plays a crucial role in anchoring the P₄ molecule and electron transport simultaneously. Uniform RP nanoparticles (∼200 nm) are obtained using a simple liquid phase method. SPAN-RP shows an initial reversible capacity of 1214 mA h g^-1 at 0.2C and retains a capacity of 860 mA h g^-1 with a high coulombic efficiency of 99.6% after 200 cycles.

Sn-Decorated red P entangled in CNTs as anodes for advanced lithium ion batteries

Phosphorus (P) is an appealing electrode material for lithium ion batteries owing to its high theoretical capacity. In particular, red P has attracted considerable research attention due to its commercial availability, low cost and easy handling. In this study, red P was combined with Sn particles and then interwoven into a carbon nanotube network (P@Sn@CNT). The electronic conductivity can be enhanced by the dual effect of the conductive CNT framework and decorated Sn particles. The Li storage capability of red P and Sn can be boosted with the synergistic effect, both contributing to the overall capacity of the composite. The P@Sn@CNT composite exhibits excellent lithium storage performance, delivering a capacity of 1197 mA h g-1 after 200 cycles at 0.2 A g-1. Outstanding cyclic stability and high rate capability are also exhibited, with a capacity retention of 79% in 200 cycles and a capacity of 911 mA h g-1 at 10 A g-1. The ex situ X-ray diffraction and X-ray photoelectron spectroscopic study also reveals the reversible lithiation mechanism of the P@Sn@CNT composite, forming Li3P and Li22Sn5. The systematic investigation on the low-cost P@Sn@CNT sheds light on the development of high-performance red P-based lithium-ion batteries for real applications.

Oxalate-derived porous prismatic nickel/nickel oxide nanocomposites toward lithium-ion battery

NiO is a highly appealing anode material for lithium-ion batteries (LIBs) owing to its relatively high Li storage capacity. However, its low electrical conductivity and large volume change during the battery cycling process limit its application. Here, we fabricate a series of porous Ni/NiO (M) nanocomposites through the direct pyrolysis of a nickel oxalate precursor and adjust the Ni(0) content by varying the pyrolysis temperature. The porous architecture is beneficial for alleviating the volume expansion/constriction during cycling. The Ni in the composites accelerates the electrochemical reaction kinetics and enhances the conductivity of the electrode materials. The M-2 electrode with a 17.9% Ni(0) content realizes a high reversible capacity (633.7 mA h g^-1 after 100 cycles at 0.2 A g^-1) and exhibits outstanding rate capability (307.6 mA h g^-1 after 250 cycles at 1 A g^-1). This work can not only supply an approach to adjust the content of an element with specific valence state, but also provide an inspiration for the fabrication of porous metal/metal oxide anode materials in LIBs.

Low-Temperature Solution Synthesis of Black Phosphorus from Red Phosphorus: Crystallization Mechanism and Lithium Ion Battery Applications

As a thermodynamically stable semiconductor material, black phosphorus (BP) has potential application in the field of energy storage and conversion. The preparation of black phosphorus is still limited to the laboratory, which is far from adequate to meet the requirements of future industrial applications. Here, the gram-scale black phosphorus is synthesized in the ethylenediamine medium using a 120-200 °C low-temperature recyclable liquid phase method directly from red phosphorus. A crystallization mechanism from red to black phosphorus based on FTIR, XPS, and DFT calculations is proposed. Black phosphorus as the anode material for lithium ion batteries is superior in discharge specific capacity, rate capability, and cycling stability in comparison with red phosphorus. The facile low-temperature synthesis of BP by the ethylenediamine-assisted liquid phase process will facilitate the extended application of BP in the field of energy storage and conversion.

Influence of Conductive additives on the stability of red phosphorus-carbon anodes for sodium-ion batteries

In this paper, the influences of conductive carbons on the red phosphorus (P) composites in sodium-ion batteries are studied. Electrochemical testing results show that Ketjen Black makes the P composites present much better cycling performances. Electrochemical impedance spectra (EIS) results indicate that when Ketjen Black is used, the total resistance of the electrode can be decreased. Since Ketjen Black is a low-cost and commercially available material, our results suggest that Ketjen Black might be a promising conductor for the alloying anodes such as P in sodium-ion batteries.

Tip-Sonicated Red Phosphorus-Graphene Nanoribbon Composite for Full Lithium-Ion Batteries

Red phosphorus (RP) is considered a promising anode material for lithium-ion batteries (LIBs) due to its high energy density and low cost. Although RP is electrically insulating, researchers have reduced its particle size and added conductive fillers to improve the electrochemical activity of RP. Here, we report a method for making <1 μm sized RP under ambient conditions by using tip sonication. A specific surfactant solution was used to stabilize the dispersion of <1 μm sized RP. Graphene nanoribbons (GNRs) were added to improve the conductivity. The RP-GNR composite achieved nearly maximum capacity at 0.1C and showed a capacity retention of 96% after 216 cycles at 0.4 C in the half-cell. When combined with a LiCoO₂ cathode, the full cell delivered a total capacity of 86 mAh/g after 200 cycles at 0.4C. This study has demonstrated the fabrication of high-performance LIBs using RP in a safe, convenient, and cost-effective manner, and the method might be extended for the preparation of other battery or catalyst materials that are difficult to acquire through bottom-up or top-down approaches.