Natural mushroom spores derived hard carbon plates for robust and low-potential sodium ion storage

Recent Progress in Improving Rate Performance of Cellulose-Derived Carbon Materials for Sodium-Ion Batteries

Cellulose-derived carbon is regarded as one of the most promising candidates for high-performance anode materials in sodium-ion batteries; however, its poor rate performance at higher current density remains a challenge to achieve high power density sodium-ion batteries. The present review comprehensively elucidates the structural characteristics of cellulose-based materials and cellulose-derived carbon materials, explores the limitations in enhancing rate performance arising from ion diffusion and electronic transfer at the level of cellulose-derived carbon materials, and proposes corresponding strategies to improve rate performance targeted at various precursors of cellulose-based materials. This review also presents an update on recent progress in cellulose-based materials and cellulose-derived carbon materials, with particular focuses on their molecular, crystalline, and aggregation structures. Furthermore, the relationship between storage sodium and rate performance the carbon materials is elucidated through theoretical calculations and characterization analyses. Finally, future perspectives regarding challenges and opportunities in the research field of cellulose-derived carbon anodes are briefly highlighted.

Noncrystalline Carbon Anodes for Advanced Sodium-Ion Storage

Developing an anode with excellent rate performance, long-cycle stability, high coulombic efficiency, and high specific capacity is one of the key research directions of sodium-ion batteries. Among all the anode materials, noncrystalline carbon (NCC) has great possibilities according to its supreme performance and low cost, but with the complexity and variability of the structure. With the in-depth study of the sodium storage behaviors of NCC in recent years, three modes of interlayer intercalation, clustering into micropores, and adsorption are reported and summarized. Although the storage mechanism has gradually become more evident, the complex behavior of the ions at different voltage regions, especially in the low-voltage (plateau) region, still remains controversial. It is essential to understand further the relationship between ions and NCC structure during energy storage processes. Based on the summary of previous works, this article has reviewed the storage mechanism of sodium ions in NCC and evaluated the structure-behavior relationship between sodium-ion storage and the carbon structure.

Jute-Fiber Precursor-Derived Low-Cost Sustainable Hard Carbon with Varying Micro/Mesoporosity and Distinct Storage Mechanisms for Sodium-Ion and Potassium-Ion Batteries

Hard carbon (HC) remains the most viable choice as a negative electrode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) owing to its higher energy density (discharge up to zero volts), higher capacity (distinct storage mechanisms), and cycling stability. Herein, a biomass jute fiber precursor HC anode (JPC) with varying porosity is reported for the first time as a low-cost and sustainable high-performance HC anode for SIBs and PIBs. Direct carbonization results in micro-meso porous HC (JPC-D), and micro-wave pretreated jute fiber results in ultramicroporous HC (JPC-M). The mesoporosity generated in JPC-D during synthesis outperforms the ultramicroporous JPC-M with a high reversible capacity of 328 mAh g^-1 (iCE = 66%) at a current density of 30 mA g^-1 (0.1C) with superior capacity retention of 84% after 100 cycles in SIBs. The Na⁺ ion and K⁺ ion storage in HCs, especially at lower voltages, shows distinct storage mechanisms that depend on the morphology and porosity of the material. JPC-D contributed 39% of its total capacity through the plateau region capacity (PRC), suggesting more pore filling from hierarchical porosity in SIBs. JPC-D and JPC-M exhibit more insertion-based capacity than pore-filling processes in PIBs. The presence of inorganic impurities (Ca, Si, Al, and Fe) encapsulated in the carbon structure plays a critical role in developing mesopores. The yield (%) of HC from direct carbonization per kilogram of jute is ∼34%, which makes it cheaper than HC from sugar-based precursors and 1.5 times more affordable than other biomass-derived HC. The jute-based micro-mesoporous HC is a novel, cost-effective, sustainable approach to designing HC for a PRC-based battery-type anode in SIBs and PIBs.

Hard Carbons as Anodes in Sodium-Ion Batteries: Sodium Storage Mechanism and Optimization Strategies

Sodium-ion batteries (SIBs) are regarded as promising alternatives to lithium-ion batteries (LIBs) in the field of energy, especially in large-scale energy storage systems. Tremendous effort has been put into the electrode research of SIBs, and hard carbon (HC) stands out among the anode materials due to its advantages in cost, resource, industrial processes, and safety. However, different from the application of graphite in LIBs, HC, as a disordered carbon material, leaves more to be completely comprehended about its sodium storage mechanism, and there is still plenty of room for improvement in its capacity, rate performance and cycling performance. This paper reviews the research reports on HC materials in recent years, especially the research process of the sodium storage mechanism and the modification and optimization of HC materials. Finally, the review summarizes the sterling achievements and the challenges on the basis of recent progress, as well as the prospects on the development of HC anode materials in SIBs.

Bacterial cellulose-derived micro/mesoporous carbon anode materials controlled by poly(methyl methacrylate) for fast sodium ion transport

An advanced nanostructure with rational micro/mesoporous distribution plays an important role in achieving high electrochemical performance in sodium ion batteries (SIBs), especially the energy storage efficiency in the low-potential region during the charging/discharging processes. Here we propose a method of polymer-blended bacterial cellulose (BC) matrix to tune the micro/mesopores of polymer-BC derived carbon under a mild carbonization temperature. The targeted pore structure and electrochemical performance are optimized by controlling the amount of methyl methacrylate monomers via free-radical polymerization, and carbonized temperature via pyrolysis treatment. The constructed carbon materials display a stable 3D fibrous network with a large specific area and abundant micro/mesopores formed during the pyrolysis of the polymer poly(methyl methacrylate) (PMMA). Taking advantage of the constructed pore structure, the optimized carbon anodes derived from BC/PMMA composites show an enhanced Na⁺ diffusion rate with a high capacity of 380.66 mA h g^-1 at 0.03 A g^-1. It is interesting that it possesses superior low-potential capacity, and retains 42% of the total capacity even at a high scan rate of 1 mV s^-1. The proposed method of polymer-blended on cellulose matrix provides an energy-efficient way to achieve high low-potential capacity under facile processing conditions for fast sodium ion transport in SIBs.

Hollow porous carbon spheres for high initial coulombic efficiency and low-potential sodium ion storage

It is critical to develop carbon material anodes with high initial Coulombic efficiency and energy density for sodium ion batteries. Herein, a novel mushroom spore with chitin as carbon precursor is first reported for energy storage, and its special porous spherical structure, fine structure and oxygen functional groups can be accurately controlled by carbonization temperature. The hollow porous carbon spheres obtained from mushroom spore at 1400 °C have appropriate porous structure, d₀₀₂ spacing (0.364 nm), 7.12% oxygen content and ultra-low specific surface area of 5.5 m² g^-1. It could obtain 81.2% initial Coulombic efficiency and has reversible discharge capacity of 411.1 mA h g^-1, wherein about 75% (308 mA h g^-1) of its total capacity is derived from low-potential plateau (below 0.1 V Na⁺/Na), and the capacity is 384.5 mA h g^-1 after 50 cycles. Furthermore, Density functional theory calculation showed that the residual oxygen functional groups (CO) in carbon materials are beneficial to sodium into graphite-like layers, and graphite-like layers spacing is smaller than the reported unadulterated carbon with 0.37 nm. Therefore, the excellent electrochemical performance and low-cost of natural mushroom spore derived hollow porous carbon spheres provide advantages for sodium ion batteries in large-scale storage devices.