Sustainable Anode Material Research Articles

Small‐Molecule Polycyclic Aromatic Hydrocarbons as Exceptional Long‐Cycle‐Life Li‐Ion Battery Anode Materials

The growing demand for cost‐effective and sustainable energy‐storage solutions has spurred interest in novel anode materials for lithium‐ion batteries (LIBs). In this study, the potential of small‐molecule polycyclic aromatic hydrocarbons (SMPAHs) as promising candidates for LIB anodes is explored. Through a comprehensive experimental approach involving electrode fabrication, material characterization, and electrochemical testing, the electrochemical performance of SMPAHs, including naphthalene, biphenyl, 9,9‐dimethylfluorene, phenanthrene, p‐terphenyl, and pyrene (Py), is thoroughly investigated. In the results, the impressive cycle stability, high specific capacity, and excellent rate capability of the SMPAH electrode are revealed. Additionally, a direct contact prelithiation strategy is implemented to enhance the initial Coulombic efficiency (ICE) of SMPAH anodes, yielding significant improvements in the ICE and cycle stability. Computational simulations provide valuable insights into the electrochemical behavior and lithium‐storage mechanisms of SMPAHs, confirming their potential as effective anode materials. The simulations reveal favorable lithium adsorption sites, the predominant storage mechanisms, and the dissolution mechanism of Py through computational calculations. Overall, in this study, the promise of SMPAHs is highlighted as sustainable anode materials for LIBs, advancing energy‐storage technologies toward a greener future.

Biomass Waste Utilization as Nanocomposite Anodes through Conductive Polymers Strengthened SiO2/C from Streblus asper Leaves for Sustainable Energy Storages.

Sustainable anode materials, including natural silica and biomass-derived carbon materials, are gaining increasing attention in emerging energy storage applications. In this research, we highlighted a silica/carbon (SiO2/C) derived from Streblus asper leaf wastes using a simple method. Dried Streblus asper leaves, which have plenty of biomass in Thailand, have a unique leaf texture due to their high SiO2 content. We can convert these worthless leaves into SiO2/C nanocomposites in one step, producing eco-materials with distinctive microstructures that influence electrochemical energy storage performance. Through nanostructured design, SiO2/C is thoroughly covered by a well-connected framework of conductive hybrid polymers based on the sodium alginate-polypyrrole (SA-PPy) network, exhibiting impressive morphology and performance. In addition, an excellent electrically conductive SA-PPy network binds to the SiO2/C particle surface through crosslinker bonding, creating a flexible porous space that effectively facilitates the SiO2 large volume expansion. At a current density of 0.3 C, this synthesized SA-PPy@Nano-SiO2/C anode provides a high specific capacity of 756 mAh g-1 over 350 cycles, accounting for 99.7% of the theoretical specific capacity. At the high current of 1 C (758 mA g-1), a superior sustained cycle life of over 500 cycles was evidenced, with over 93% capacity retention. The research also highlighted the potential for this approach to be scaled up for commercial production, which could have a significant impact on the sustainability of the lithium-ion battery industry. Overall, the development of green nanocomposites along with polymers having a distinctive structure is an exciting area of research that has the potential to address some of the key challenges associated with lithium-ion batteries, such as capacity degradation and safety concerns, while also promoting sustainability and reducing environmental impact.

Bio-based anode material production for lithium–ion batteries through catalytic graphitization of biochar: the deployment of hybrid catalysts

Producing sustainable anode materials for lithium-ion batteries (LIBs) through catalytic graphitization of renewable biomass has gained significant attention. However, the technology is in its early stages due to the bio-graphite's comparatively low electrochemical performance in LIBs. This study aims to develop a process for producing LIB anode materials using a hybrid catalyst to enhance battery performance, along with readily available market biochar as the raw material. Results indicate that a trimetallic hybrid catalyst (Ni, Fe, and Mn in a 1:1:1 ratio) is superior to single or bimetallic catalysts in converting biochar to bio-graphite. The bio-graphite produced under this catalyst exhibits an 89.28% degree of graphitization and a 73.95% conversion rate. High-resolution transmission electron microscopy (HRTEM) reveals the dissolution–precipitation mechanism involved in catalytic graphitization. Electrochemical performance evaluation showed that the trimetallic hybrid catalyst yielded bio-graphite with better electrochemical performances than those obtained through single or bimetallic hybrid catalysts, including a good reversible capacity of about 293 mAh g−1 at a current density of 20 mA/g and a stable cycle performance with a capacity retention of over 98% after 100 cycles. This study proves the synergistic efficacy of different metals in catalytic graphitization, impacting both graphite crystalline structure and electrochemical performance.

Crystallization-induced formation of two-dimensional carbon nanosheets derived from sodium lignosulfonate for fast lithium storage

Sodium lignosulfonate, an abundant natural resource, is regarded as an ideal precursor for the synthesis of hard carbon. The development of high-performance, low-cost and sustainable anode materials is a significant challenge facing lithium-ion batteries (LIBs). The modulation of morphology and defect structure during thermal transformation is crucial to improve Li+ storage behavior. Synthesized using sodium lignosulfonate as a precursor, two-dimensional carbon nanosheets with a high density of defects were produced. The synergistic influence of ice templates and KCl was leveraged, where the ice prevented clumping of potassium chloride during drying, and the latter served as a skeletal support during pyrolysis. This resulted in the formation of an interconnected two-dimensional nanosheet structure through the combined action of both templates. The optimized sample has a charging capacity of 712.4 mA h g−1 at 0.1 A g−1, which is contributed by the slope region. After 200 cycles at 0.2 A g−1, the specific charge capacity remains 514.4 mA h g−1, and a high specific charge capacity of 333.8 mA h g−1 after 800 cycles at 2 A g−1. The proposed investigation offers a promising approach for developing high-performance, low-cost carbon-based anode materials that could be used in advanced lithium-ion batteries.

Electrochemical characterization of γ-Fe2O3 and reduced graphene oxide composite as a sustainable anode material for Na-ion batteries

In this paper we report the synthesis and characterization of a γ-Fe2O3/reduced graphene oxide composite anode for Na-ion batteries. The nanocomposite anode is synthesized by a facile and green method....

Electrochemical storage systems: Safer and more sustainable batteries

Lithium-ion batteries (LIBs) are the predominant power source for portable electronic devices, and in recent years their use has extended to higherenergy and larger devices. However, to satisfy the stringent requirements of safety and energy density, further material advancements are required. Due to the inherent flammability of organic solvent-based liquid electrolytes and their instability against materials utilized in high-energy systems, a transition to alternative ionconductive media becomes urgent. In this paper, some possible solutions, shifting from molecular liquids to a class of materials based on ions, such as ionic liquids (ILs), and polymers, such as gel polymer electrolytes (GPEs), will be briefly discussed. Moreover, innovative technologies, the so-called beyond-lithium batteries, will be presented, considering a more sustainable anode material based on calcium.

Boosting the Initial Coulombic Efficiency of Sustainable Hard Carbon Derived from Polyethylene Terephthalate with Cyclopentyl Methyl Ether As a Co-Solvent for Wide-Temperature Sodium-Ion Batteries

Upcycling plastic waste into value-added products helps to generate cost-effective and sustainable resources towards a circular materials economy and safer ecosystem. The conversion of polyethylene terephthalate (PET) municipal waste via the carbonization process into hard carbon (HC) delivers a high-reversible capacity, low-cost, sustainable anode material for sodium-ion batteries (SIBs). However, the low initial Coulombic efficiency (ICE) is a significant challenge of the HC anode, which should be optimized by electrolyte and interfacial chemistry.1 In conventional carbonate esters-based electrolytes, ethylene carbonate (EC) forms an organic-rich thick SEI layer, soluble on cycling, limiting the cyclic stability. The low-temperature performance is also a significant concern in achieving high capacity, long cyclability, and ICE.2 Herein, HC derived via single-step carbonization at 1000℃ exhibits larger interlayer spacing of 0.379 nm, low surface area (~205 m2g-1), and unique slit-shaped pores with 84% mesoporosity in the structure. PET-HC exhibits a high reversible capacity of 337 mAh g-1 with ICE of just 66%, using EC-PC-based electrolyte. EC-free cyclopentyl methyl ether (CPME) was used due to its weakly solvating and wide temperature solvent.3 CPME-PC-based electrolytes significantly enhanced the ICE value to 74.5% and reversible capacity to 356 mAh g-1 with superior cycling of 91% after 100 cycles at 0.1C rate. The inorganic-rich SEI layer for CPME-PC-based electrolytes results in a thin SEI that improves the ICE and cyclic stability of the anode. The low-temperature performance (up to -20°C) for CPME-PC-based electrolytes showed ~30% added capacity compared to EC-PC-based electrolytes. This work provided an eco-friendly approach to developing hard carbons from plastic trash and offered an effective strategy to replace EC with CPME for low-temperature sodium storage applications. References Shen, L., Shi, S., Roy, S., Yin, X., Liu, W., Zhao, Y., Adv. Funct. Mater. 2021, 31, 2006066. Ramasamy, H. V., Kim, S., Adams, E. J., Rao, H. & Pol, V. G. Chem. Commun. 2022, 58, 5124–5127.Zhang, H., Zeng, Z., Ma, F., Wu, Q., Wang, X., Cheng, S., Xie, J., Angew. Chem. 2023, e202300771. Figure 1

Easily-prepared macroporous-mesoporous carbon from palm fiber as a sustainable anode for high-performance microbial fuel cells

Anode material plays a pivotal role in increasing the performance of microbial fuel cells (MFCs). In this study, macroporous-mesoporous carbon derived from palm fiber (PF) as sustainable anode material was easily prepared via H3PO4 activation followed by carbonization. The MFC with palm fiber derived anode achieved a maximum power density of 718.15 mW m-2, which was 3.89 times higher than that of carbon cloth anode (146.78 mW m-2). P element was doped on PF anode by H3PO4 activation, which significantly improved the anodic hydrophilicity. The specific surface area (SSA), microporous structure, and P content of PF anode were significantly increased while O content was decreased when carbonization temperature increased from 500 °C to 900 °C. Collectively, PF anode was characteristic with high electrochemical performance and facile fabrication, which exhibiting great application potentials as an ideal MFC anode material in future.

Rational regulation of defect-rich hierarchical porous carbon nanosheets as sustainable anode materials for potassium-ion storage

Potassium-ion storage devices are the most promising equipment for large-scale energy storage due to their low cost and abundant resource. However, the low rate and poor cycling ability of potassium-ion energy storage devices resulting from the dramatic structure changes of electrode materials during operation limit their development. Herein, a defect-rich hierarchical porous carbon nanosheets (HPCS) is successfully synthesized via a facile Mg(OH)2 template approach with low-cost coal tar pitch as carbon precursor. The ultrathin nanosheets framework with a porous structure not only accelerates the rapid infiltration of electrolyte, but also alleviates the volume expansion upon cycling. Benefiting from its unique microstructure, the optimized HPCS-900 exhibits excellent rate performance (156.2 mAh g−1 at 1 A g−1) and cycling stability (130.1 mAh g−1 at 1 A g−1 after 1000 cycles). As a practical device application, the assembled potassium-ion capacitors (HPCS//AC) deliver a high energy density of 130 Wh kg−1 and a maximum power density of 10,735 W kg−1. This work provides an exciting approach to designing advanced defect-structured carbon-based materials for high-performance potassium-ion batteries and capacitors.

Comparative performance of sustainable anode materials in microbial fuel cells (MFCs) for electricity generation from wastewater

Microbial fuel cells (MFCs) are a promising technology to generate electricity from wastewater and reduce the organic content. Whilst there has been a significant enhancement in MFC efficiency arising from the introduction of novel materials and cell designs, challenges remain with respect to the performance, cost, and sustainability of anode materials. This paper reports the development of single chamber MFCs with a focus on novel, cost-effective, and recycled carbon-based anode materials, including Recycled Water Filter Block/Powder (RWFB/RWFP), Recycled Chopped Carbon Fibre (RCCF), Carbon Felt (CF) and Graphite Flexible powder (GFG). Anodes prepared from GFG were shown to provide high power density (342.8 mW/m2), followed by RCCF, CF, RWFP, RWFB and CF (77.6, 71.8, 59.0 and 57.9 mW/m2, respectively). Chemical Oxygen Demand (COD) reduction was measured initially and at day 30, with GFG anodes observed to remove 83% of the initial load, compared to RCCF, RWFB, RWFP and CF anodes, where COD reductions of 69%, 61%, 65% and 73% were observed, respectively. Electrochemical analysis and biofilm imaging confirmed recycled materials were colonised by microorganisms and performed to high standards. GFG offers significant promise as an anode material, with excellent performance supported by a reduction in capital cost of up to 90% in comparison to CF. The use of recycled carbon material as MFC anodes shows promise, but requires additional work to improve the stability and durability of systems to permit scale-up.

Deep eutectic solvents assisted biomass pre-treatment to derive sustainable anode materials for lithium-ion batteries

Biomass such as agricultural waste is an attractive and sustainable source to produce electrode materials for energy storage systems. The pre-treatment of biomass is a key process that determines the quality of resulting material and consequently defines the performance of the device. In common practice, aggressive and toxic chemicals such as inorganic acids and alkaline solvents have extensively been used, which threatens environmental and human health. Herein, we have presented deep eutectic solvents (DES)-based green, inexpensive and effective solvents for the pre-treatment of rice-husk (RH) biomass. The results demonstrate that DES efficiently and selectively remove the inorganic impurities from RH without affecting their organic content. Later, the DES pre-treated RH were transformed into silicon/carbon (Si/C) nanocomposite using single step pyrolysis method and employed as anode materials for lithium-ion battery (LIB). It was revealed that DES significantly affects the structural and morphological properties of resulting Si/C materials. Benefiting from the unique hierarchical characteristics of Si/C nanocomposites, all the samples delivered excellent electrochemical properties with maximum specific capacity of 372.5 mAh/g and pro-longed cycling stability. Thus, the present investigation provides green and cost-effective strategy for pre-treatment of rice-husk, which can be further extended to various biomass.

Electrochemically Exfoliated Layered Carbons as Sustainable Anode Materials for Lead Carbon Hybrid Ultracapacitor

AbstractLead‐carbon hybrid ultracapacitors (Pb−C HUC) have become apparent as a way out of the sulfation issue of lead‐acid batteries, simultaneously enhancing the system‘s power density and cycle life. In this work, exfoliated graphene oxides (EGO) were synthesized by the electrochemical exfoliation method followed by chemical activation and carbonization at 600 °C (AEGO‐600). The composite electrode delivered 800 F g−1 capacitance at 1 A g−1. The Pb−C HUC fabricated using AEGO‐600 anode and PbO2 cathode can achieve capacitance of 325 F g−1 at 10 A g−1 and retain 71 % capacitance after 15000 charge‐discharge cycles in the voltage range of 2.3–0.8 V. The highly stable capacitance was due to the formation of layered carbons in AEGO‐600 that enhanced the favorable electrolyte ion assessment to maximum active sites. Owing to the facile, cost‐effective synthesis approach and better charge storage behavior, the activated‐exfoliated graphene oxides thus produced could be suitable candidates for future hybrid ultracapacitor systems.

Quinone Electrodes for Alkali-Acid Hybrid Batteries.

Aqueous batteries are promising candidates for large-scale energy storage but face either limited energy density (lead-acid batteries), cost/resource concerns (Ni-MH batteries), or safety issues due to metal dendrite growth at high current densities (zinc batteries). We report that through designing electrochemical redox couples, quinones as intrinsic dendrite-free and sustainable anode materials demonstrate the theoretical energy density of 374 W h kg-1 coupling with affordable Mn2+/MnO2 redox reactions on the cathode side. Due to the fast K-ion diffusion in the electrolyte, low K-ion desolvation energy at the interface, and fast quinone/phenol reaction, the optimized poly(1,4-anthraquinone) in the KOH electrolyte shows specific capacities of 295 mA h g-1 at 300 C-rate and 225 mA h g-1 at 240 mA cm-2. Further constructed practical aqueous batteries exhibit an output voltage of 2 V in alkali-acid hybrid electrolyte systems with exceptional electrochemical kinetics, which can release/store over 95% of the theoretical capacity in less than 40 s (25 000 mA g-1). The scaled Ah level aqueous battery with the upgradation of interfacial chemistry on the electrode current collector exhibits an overall energy density of 92 W h kg-1, exceeding commercial aqueous lead-acid and Ni-MH batteries. The rapid response, intrinsic dendrite-free existence, and cost efficiency of quinone electrodes provide promising application interests for regulating the output of the electricity grid generated by intermittent solar and wind energy.

The Role of Hydrothermal Carbonization in Sustainable Sodium‐Ion Battery Anodes

AbstractSodium‐ion batteries as a prospective alternative to lithium‐ion batteries are facing the challenge of developing high‐performance, low‐cost and sustainable anode materials. Hard carbons are appropriate to store sodium ions, but major energy and environmental concerns during their fabrication process (i.e., high‐temperature carbonization) have not been properly assessed. Furthermore, the rational design of high‐performing hard carbon anodes is usually limited by the conventional direct carbonization of organic precursors. Here, the hydrothermal carbonization process is employed as a versatile pre‐treatment method of renewable precursors, followed by high‐temperature carbonization, for producing advanced hard carbon anodes. The critical role of hydrothermal pre‐treatment in regulating the structure for an optimized performance of hard carbon anodes is elucidated, while revealing the sodium‐ion storage mechanism using electrochemical kinetic calculations, advanced characterization and multi‐scale modeling. Furthermore, the environmental impacts of hydrothermal pre‐treatment and subsequent carbonization are evaluated using life cycle assessment compared to direct carbonization. By comparing hard carbon anodes with and without the hydrothermal pre‐treatment, it is verified that the additional hydrothermal process is responsible for enhanced electrochemical performance, increased carbon yields and reduced carbon emissions. The work provides a systematic understanding of functions and energy consumptions of hydrothermal systems to achieve next‐generation sustainable sodium‐ion batteries.

Bismuth telluride anode boosting highly reversible electrochemical activity for potassium storage

To ensure high capacity with reasonable cycling stability using the conversion or K-alloy reaction, the anode should minimize or embrace the volume expansion during the discharge (potassiation) and charge (depotassiation) processes. Herein, we report on a Bi2Te3 composite modified by nanosized carbon that boosts the highly reversible capacity with long cycling stability. The as-synthesized Bi2Te3 powders and acetylene black carbon were compositized via high-energy ball-milling, resulting in improvement of the electrical conductivity to ∼10−4 S cm−1 from ∼10−7 S cm−1. Electrochemical investigation revealed that the proposed Bi2Te3@C retained over 79.8% of its initial capacity (311 mAh g− 1) for 500 cycles at a current of 1000 mA g− 1. We unveil the reaction chemistry behind the acceptable performance using operando X-ray diffraction, X-ray absorption near edge structure spectroscopy, and time-of-flight secondary-ion mass spectrometry. The Bi2Te3 undergoes a conversion reaction to form Bi0 metal and K2Te as a conversion byproduct, after which Bi is further potassiated to K3Bi. The highly reversible behavior is attributed to the enlargement of the active area along with the filling of voids among Bi2Te3 particles by nanosized carbons in the composite electrode, enabling not only facile electron transport but also preservation of the electrode shape even after long-term cycling. Our approach highlights the feasibility of applying Bi2Te3@C as a sustainable anode material for potassium-ion batteries.

Effects of surface functional groups of coal-tar-pitch-derived nanoporous carbon anodes on microbial fuel cell performance

Coal tar pitch, the residue generated from distillation of coal tar, is cheap, abundant, and carbon enriched. This paper evaluates the effects of the surface modification of coal-tar pitch-derived nanoporous carbons (NPCs) as anode materials on the performance of Escherichia coli (E. coli)-based microbial fuel cells (MFCs) for the first time. The coal-tar pitch precursors are heated under N2 to 450 °C (450O) and 750 °C (750X) to obtain NPCs with different concentrations of oxygen-containing functional groups. 750X is, thereafter, doped with nitrogen atoms to generate a nitrogen-doped NPCs (750N). More biofilm is formed on the 750N anode than the 750X or 450O anode because of the higher electrical conductivity and biocompatibility of 750N. As a result, a higher power output of MFC is obtained when the 750N anode is used. The maximum power density of 750N is 3772 mW m−2, while that of 750X and 450O are 2876 mW m−2 and 3562 mW m−2, respectively, demonstrating that 750N is a potential sustainable anode material for high-performance MFC applications.

Graphene‐integrated CuCo 2 S 4 microspheres as a sustainable anode material for high‐performance Li‐ion batteries

Commercial lithium–ion batteries (LIBs) are insufficient to bridge the energy density gap between demand and supply in advanced heavy and portable electronic devices because of graphite anodes (poor theoretical capacity: 372 mAh g−1). Ternary chalcogenide metal‐sulfides are promising as alternative anode materials in high power and energy densities but suffer from capacity fading with poor long‐term cycling stability due to the dissolution of polysulfide species created during the lithium‐ion insertion/de‐insertion process. Here, we report the hydrothermal synthesis of graphene integrated CuCo2S4 microparticles as a high‐capacity and sustainable anode material for LIBs. We solve the concentration gradient of lithium polysulfide at the interface of electrode/electrolyte via integrating graphene into the active metal sulfide anode material. The mechanically flexible and highly conductive nature of graphene helps relieve undesirable elongation and shrinkage during battery cycling, suppressing active material dissolution and enhancing electron/ion transport through the electrochemical double‐layer (EDL). Our one step approach demonstrates towards the practical application of advanced metal sulfide anodes for LIBs.

Electrolytic alloy-type anodes for metal-ion batteries

Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries (MIBs) because of their theoretical high gravimetrical capacities. Semimetals and semimetal-analogs are typical alloy-type anodes. Currently, the large-scale extraction of semimetals (Si, Ge) and semimetal-analogs (Sb, Bi, Sn) by traditional metallurgical routes highly relies on using reducing agents (e.g., carbon, hydrogen, reactive metals), which consumes a large number of fossil fuels and produces greenhouse gas emissions. In addition, the common metallurgical methods for extracting semimetals involve relatively high operating temperatures and therefore produce bulk metal ingots solidified from the liquid metals. However, the commonly used electrode materials in batteries are fine powders. Thus, directly producing semimetal powders would be more energy efficient. In addition, semimetals are good candidates to host alkali/alkaline-earth ions through the alloying process because the electronegativity of semimetals is high. Therefore, preparing semimetal powders via an environment-sound manner is of great interest to provide sustainable anode materials for MIBs while reducing the ecological footprint. Low-cost and high-output capacity anode powder materials, as well as straightforward and environmental-benign synthetic methods, play key roles in enabling the energy conversion and storage technologies for real applications of MIBs. Electrochemical technologies offer new strategies to extract semimetals using electrons as the reducing agent that comes from renewable energies. Besides, the morphologies and structures of the electrolytic products can be rationally tailored by tuning the electrode potentials, electrolytes, and operating temperatures. In this regard, using the one-step green electrochemical method to prepare high-capacity and cheaper alloy-type metalloids for MIB anodes can fulfill the requirements for developing MIBs. This review critically overviews recent developments and advances in the electrochemical extraction of semimetals (Si, Ge) and semimetal-analogs (Sb, Bi, Sn) for MIBs, including basic electrochemical principles, thermodynamic analysis, manufacture strategies and applications in lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), potassium-ion batteries (PIBs), magnesium-ion batteries (Mg-ion batteries), and liquid metal batteries (LMBs). It also presents challenges and prospects of employing electrochemical approaches for preparing alloy-type anode materials directly from inexpensive ore-originated feedstocks.

Synthesis of 3D-structured Li4Ti5O12 from titanium(IV) oxysulfate (TiOSO4) solution as a highly sustainable anode material for lithium-ion batteries

Because of its excellent safety and sustainability, spinel-structured lithium titanate (LTO, Li4Ti5O12) has recently attracted intensive attention as a promising anode material for lithium-ion batteries (LIBs) for large-scale applications. However, several obstacles impede the use of LTO in practical applications, including its high cost and relatively low capacity due to poor electron conductivity. To reduce the synthesis cost and increase the efficiency of LTO, LTO microspheres assembled with nanoparticles were prepared from a titanium(IV) oxysulfate (TiOSO4) solution, which is generally produced during the sulfate process in titanium mining of ilmenite (FeTiO3). Before LTO microspheres were synthesized, 1–2 μm microsphere scaffolds consisting of TiO2 nanoparticles were prepared through the urea-based hydrolysis of TiOSO4. The LTO microspheres were obtained through a sequential hydrothermal reaction–calcination process using LiOH and the as-prepared TiO2 microsphere scaffolds. According to the synthesis conditions, LTO–TiO2 (LTO-500), nonporous LTO (LTO-800), and porous LTO (LTO-HT3-500) microspheres were synthesized. The electrochemical performances of the synthesized LTO microspheres were most strongly affected by the microspheres’ crystal size and surface area. The presence of TiO2 in the LTO microspheres also affected their performance. The LTO-HT3-500 microspheres (pure spinel LTO phase) showed an excellent initial discharge capacity of 158.7 mAh/g, superior cyclic ability (<7.3% capacity decay, 100 cycles at 1C), and rate capability (capacity loss 11%) at high current rates (0.1C–10C) because of their small crystal size (17.6 nm) and large specific surface area (44.4 m2/g). These results demonstrate that high-performance LTO microspheres for LIBs can be produced from TiOSO4 solution as a low-cost Ti source.

Wood-Derived Carbon with Selectively Introduced C═O Groups toward Stable and High Capacity Anodes for Sodium Storage.

Biomass-derived carbon is a promising sustainable anode material for sodium-ion batteries (SIBs). Although the electrochemical performance can be improved by introducing functional groups, the selective introduction of single functional groups into biomass carbon remains difficult. Here, we overcome this challenge by developing a wood-derived carbon with selectively introduced C═O groups by combining tetramethoxysilane (TMOS) with wood cellulose pulps. The integration of TMOS introduces abundant C═O groups into the carbon during the polycondensation and pyrolysis process. The C═O groups play a dominant role in anode surface-controlled processes, and this leads to improvements in pseudo-capacity and fast electrode process kinetics. Besides, the introduction of C═O groups generates oxygen functional active sites that promote Na+ adsorption and creates a sufficiently largegraphene interlayer distance. The as-obtained carbon shows a high capacity of 330 mAh g-1 at 40 mA g-1 and excellent cycling stability. Moreover, our strategy is simple and uses wood cellulose pulps as precursors. It therefore enables low-cost and large-scale synthesis of carbon anode materials for SIBs.