Bacteria-Derived Biological Carbon Building Robust Li-S Batteries

Biomass-Derived Materials for Advanced Rechargeable Batteries

Biomass-derived materials generally exhibit uniform and highly-stable hierarchical porous structures that can hardly be achieved by conventional chemical synthesis and artificial design. When used as electrodes for rechargeable batteries, these structural and compositional advantages often endow the batteries with superior electrochemical performances. This review systematically introduces the innate merits of biomass-derived materials and their applications as the electrode for advanced rechargeable batteries, including lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, and metal-sulfur batteries. In addition, biomass-derived materials as catalyst supports for metal-air batteries, fuel cells, and redox-flow batteries are also included. The major challenges for specific batteries and the strategies for utilizing biomass-derived materials are detailly introduced. Finally, the future development of biomass-derived materials for advanced rechargeable batteries is prospected. This review aims to promote the development of biomass-derived materials in the field of energy storage and provides effective suggestions for building advanced rechargeable batteries.

Formation of 2D Amorphous Lithium Sulfide Enabled by Mo2C Clusters Loaded Carbon Scaffold for High-Performance Lithium Sulfur Batteries

Lithium-sulfur (Li-S) batteries, operated through the interconversion between sulfur and solid-state lithium sulfide, are regarded as next-generation energy storage systems. However, the sluggish kinetics of lithium sulfide deposition/dissolution, caused by its insoluble and insulated nature, hampers the practical use of Li-S batteries. Herein, leaf-like carbon scaffold (LCS) with the modification of Mo2C clusters (Mo2C@LCS) is reported as host material of sulfur powder. During cycles, the dissociative Mo ions at the Mo2C@LCS/electrolyte interface are detected to exhibit competitive binding energy with Li ions for lithium sulfide anions, which disrupts the deposition behavior of crystalline lithium sulfide and trends a shift in the configuration of lithium sulfide toward an amorphous structure. Combining the related electrochemical study and first-principle calculation, it is revealed that the formation of amorphous lithium sulfides shows significantly improved kinetics for lithium sulfide deposition and decomposition. As a result, the obtained Mo2C@LCS/S cathode shows an ultralow capacity decay rate of 0.015% per cycle at a high mass loading of 9.5 mg cm-2 after 700 cycles. More strikingly, an ultrahigh sulfur loading of 61.2 mg cm-2 can also be achieved. This work defines an efficacious strategy to advance the commercialization of Mo2C@LCS host for Li-S batteries.

Undercoordination Chemistry of Sulfur Electrocatalyst in Lithium-Sulfur Batteries

Undercoordination chemistry is an effective strategy to modulate the geometry-governed electronic structure and thereby regulate the activity of sulfur electrocatalysts. Efficient sulfur electrocatalysis is requisite to overcome the sluggish kinetics in lithium-sulfur (Li-S) batteries aroused by multi-electron transfer and multi-phase conversions. Recent advances unveil the great promise of undercoordination chemistry in facilitating and stabilizing sulfur electrochemistry, yet a related review with systematicness and perspectives is still missing. Herein, it is carefully combed through the recent progress of undercoordination chemistry in sulfur electrocatalysis. The typical material structures and operational strategies are elaborated, while the underlying working mechanism is also detailly introduced and generalized into polysulfide adsorption behaviors, polysulfide conversion kinetics, electron/ion transport, and dynamic reconstruction. Moreover, perspectives on the future development of undercoordination chemistry are further proposed.

Heterostructures Regulating Lithium Polysulfides for Advanced Lithium-Sulfur Batteries

Sluggish reaction kinetics and severe shuttling effect of lithium polysulfides seriously hinder the development of lithium-sulfur batteries. Heterostructures, due to unique properties, have congenital advantages that are difficult to be achieved by single-component materials in regulating lithium polysulfides by efficient catalysis and strong adsorption to solve the problems of poor reaction kinetics and serious shuttling effect of lithium-sulfur batteries. In this review, the principles of heterostructures expediting lithium polysulfides conversion and anchoring lithium polysulfides are detailedly analyzed, and the application of heterostructures as sulfur host, interlayer, and separator modifier to improve the performance of lithium-sulfur batteries is systematically reviewed. Finally, the problems that need to be solved in the future study and application of heterostructures in lithium-sulfur batteries are prospected. This review will provide a valuable reference for the development of heterostructures in advanced lithium-sulfur batteries.

Optimized Morphology and Tuning the Mn3+ Content of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries

The advantages of cobalt-free, high specific capacity, high operating voltage, low cost, and environmental friendliness of spinel LiNi_0.5Mn_1.5O₄ (LNMO) material make it one of the most promising cathode materials for next-generation lithium-ion batteries. The disproportionation reaction of Mn³⁺ leads to Jahn-Teller distortion, which is the key issue in reducing the crystal structure stability and limiting the electrochemical stability of the material. In this work, single-crystal LNMO was synthesized successfully by the sol-gel method. The morphology and the Mn³⁺ content of the as-prepared LNMO were tuned by altering the synthesis temperature. The results demonstrated that the LNMO_110 material exhibited the most uniform particle distribution as well as the presence of the lowest concentration of Mn³⁺, which was beneficial to ion diffusion and electronic conductivity. As a result, this LNMO cathode material had an optimized electrochemical rate performance of 105.6 mAh g^-1 at 1 C and cycling stability of 116.8 mAh g^-1 at 0.1 C after 100 cycles.

Simultaneously Suppressing Shuttle Effect and Dendrite Growth in Lithium-Sulfur Batteries via Building Dual-Functional Asymmetric-Cellulose Gel Electrolyte

Polysulfides huttling and interfacial instability of Lithium-anode are the main technical issues hindering commercialization of high-energy-density lithium-sulfur batteries. Simply addressing the problem of polysulfide shuttling or lithium dendrite growth can result in safety hazards or short lifespan. To synchronously tackle the aforementioned issues, the authors have designed an asymmetric cellulose gel electrolyte, a defective and ionized UiO66/black phosphorus heterostructure coating layer (Di-UiO66/BP) and a cationic cellulose gelelectrolyte (QACA). Defective and ionized engineered UiO66 particles significantly enhances performance of UiO66/BP layer in anchoring free polysulfides, promoting smooth and effective polysulfide conversion and expediting the redox kinetics of sulfur cathode, therefore suppressing polysulfide shuttling. QACA electrolyte with numerous cationic groups can interact with anions via electrostatic adsorption, thus enhancing lithium-ion transference number and contributing to formation of stable solid electrolyte interface to suppress lithium dendrite growth. Owing to the superior performance of QACA/Di-UiO66/BP, the final cells exhibit outstanding electrochemical performance, presenting high sulfur utilization (1420.1 mAh g^-1 at 0.1 C), high-rate capacity (665.4 mAh g^-1 at 4 C) and long cycle lifespan. This work proposes a strategy of designing asymmetric electrolytes to simultaneously address the challenges in both S-cathode and Li-anode, which contributes to advanced Li-S batteries and their practical application.

A soil-inspired dynamically responsive chemical system for microbial modulation

Interactions between the microbiota and their colonized environments mediate critical pathways from biogeochemical cycles to homeostasis in human health. Here we report a soil-inspired chemical system that consists of nanostructured minerals, starch granules and liquid metals. Fabricated via a bottom-up synthesis, the soil-inspired chemical system can enable chemical redistribution and modulation of microbial communities. We characterize the composite, confirming its structural similarity to the soil, with three-dimensional X-ray fluorescence and ptychographic tomography and electron microscopy imaging. We also demonstrate that post-synthetic modifications formed by laser irradiation led to chemical heterogeneities from the atomic to the macroscopic level. The soil-inspired material possesses chemical, optical and mechanical responsiveness to yield write-erase functions in electrical performance. The composite can also enhance microbial culture/biofilm growth and biofuel production in vitro. Finally, we show that the soil-inspired system enriches gut bacteria diversity, rectifies tetracycline-induced gut microbiome dysbiosis and ameliorates dextran sulfate sodium-induced rodent colitis symptoms within in vivo rodent models.

Highlighting the Implantation of Metal Particles into Hollow Cavity Yeast-Based Carbon for Improved Electrochemical Performance of Lithium–Sulfur Batteries

The introduction of metal particles into microbe-based carbon materials for application to lithium–sulfur (Li–S) batteries has the three major advantages of pore formation, chemisorption for polysulfides, and catalysis of electrochemical reactions. Metal particles and high specific surface area are often considered to enhance the properties of Li–S batteries. However, there are few data to support the claim that metal particles implanted in microbe-based carbon hosts can improve Li–S battery performance without interfering with the specific surface area. In this work, hollow-cavity cobalt-embedded yeast-based carbon (HC–Co–YC) with low specific surface area was successfully produced by impregnating yeast cells with a solution containing 0.075 M CoCl2 (designated as HC–Co–YC–0.075M). Cobalt particles implanted in yeast carbon (YC) could improve the conductive properties, lithium-ion diffusion, and cycling stability of the sulfur cathode. Compared to previously reported counterpart electrodes without metal particles, the HC–Co–YC–0.075M/S electrode in this study had a high initial specific capacity of 1061.9 mAh g−1 at 0.2 C, maintained a reversible specific capacity of 504.9 mAh g−1 after 500 cycles, and showed a capacity fading rate of 0.1049% per cycle. In conclusion, the combination of cobalt particles and YC with low specific surface area exhibited better cycle stability, emphasizing the importance of implantation of metal particles into carbon hosts for improving the electrochemical properties of Li–S batteries.

Cationic Covalent Organic Framework as Separator Coating for High-Performance Lithium Selenium Disulfide Batteries

Selenium disulfide that combines the advantages of S and Se elements is a new material for Li-chalcogen battery cathodes. However, like Li-S batteries, the shuttle effect seriously restricts the performance of Li-SeS2 batteries. In this work, we have synthesized a kind of nitrogen-rich lithophilic covalent organic framework (ATG-DMTZ-COF) as a separator coating material for Li-SeS2 batteries. Here, the N atom in the ATG-DMTZ-COF channel preferentially interacts with the lithium ion in the electrolyte to form N…Li bond, which significantly improves the diffusion coefficient of lithium ions during the charge and discharge. More importantly, we prove that the pore size of ATG-DMTZ-COF will decrease sharply because there is a large amount of TFSI- in the channel, and finally the shuttling of polysulfide and polyselenide is suppressed by the sieving effect. As a consequence, Li-SeS2 batteries using the ATG-DMTZ-COF separator coating show excellent performances with an initial discharge capacity of 1028.7 mAh g−1 at 0.5 C under a SeS2 loading of 2.38 mg cm−2. Furthermore, when the current density is 1C, the specific capacity of 404.7 mAh g−1 can be maintained after 700 cycles.

Confining ZnS/SnS2 Ultrathin Heterostructured Nanosheets in Hollow N-Doped Carbon Nanocubes as Novel Sulfur Host for Advanced Li-S Batteries

Hollow nanostructured hosts are important scaffolds to achieve high sulfur loading, fast charge transfer, and conspicuous restraint of lithium polysulfides (LiPSs) shuttling in lithium-sulfur (Li-S) batteries. However, developing high-efficiency hollow hosts for improving utilization and conversion of aggregated sulfur in the hollow chamber remains a longstanding challenge. Herein, hollow N-doped carbon nanocubes confined petal-like ZnS/SnS₂ heterostructures (ZnS/SnS₂ @NC) as a conceptually novel host for Li-S batteries are reported. Specifically, compared to consubstantial hollow double-shelled hosts, the ZnS/SnS₂ @NC with higher effective active surface area brings dense contact with sulfur and enhances efficient adsorption sites for binding LiPSs and accelerating their conversion. Benefiting from the unique structure and sophisticated composition, the resulting S@ZnS/SnS₂ @NC cathodes exhibit 1294 mAh g^-1 at 0.2 C, an ultralow capacity decay of 0.016% per cycle over 500 cycles at 1.0 C, and a high area capacity of 4.77 mAh cm^-2 at 0.5 C (5.9 mg cm^-2 ). Meanwhile, the performance evolution of S@ZnS/SnS₂ @NC cathodes under various sulfur loadings is further investigated by using EIS, which provides the beneficial guidance to explore viable strategies further optimizing their performance. This work sheds new insights into the design of hollow nanostructured hosts with a distinguished ability to regulate LiPSs in Li-S batteries.

Revealing the synergistic mechanism of multiply nanostructured V2O3 hollow nanospheres integrated with doped N, Ni heteroatoms, in-situ grown carbon nanotubes and coated carbon nanolayers for the enhancement of lithium-sulfur batteries

Lithium sulfur (Li-S) batteries are regarded as one of the most promising future energy storage candidates on account of high theoretical specific capacity of 1675 mAh g^-1 and energy density of 2600 Wh kg^-1. However, their practical application is seriously hindered due to the poor conductivity and volume expansion of sulfur, the weak redox kinetics of lithium polysulfide (LPS), and the severe shuttle effect of LPS. Herein, V₂O₃@N,Ni-C nanostructures, multiply integrated with zero-dimensional (0D) V₂O₃ nanoparticles, 1D carbon nanotubes, 2D carbon coating layers and graphene, 3D hollow spheres, and doped N and Ni heteroatoms, were synthesized via a solvothermal method followed by chemical vapor deposition. After being used as a modifier for traditional commercial separator of Li-S batteries, the shuttle effect of LPS can be effectively suppressed owing to the abundant active physical and chemical adsorption sites derived from large specific surface area, rich porosity, and tremendous polarity of the V₂O₃ nanoparticles with multiple secondary nanostructure integration. Meanwhile, the transfer of Li⁺ ions and electrons can be effectively enhanced by the highly conductive 2D carbon network, and the kinetics of redox reaction (Li₂S_n ↔ Li₂S) can be accelerated by the doped N and Ni heteroatoms, leading to a synergistic promotion on the reutilization of the adsorbed LPS. Additionally, the unique 3D hollow structure can not only enhance the penetration of electrolyte, but also buffer the volume expansion of sulfur to some extent. Therefore, the rate capacity and cycling performance can be significantly enhanced by the multifunction synergism of adsorption, conductivity, catalysis, and volume buffering. An initial discharge capacity of 1590.4 mAh g^-1can be achieved at 0.1C, and the discharge capacity of 803.5 mAh g^-1can be still exhibited when increasing to 2C. After a long period of 500 cycles, additionally, the discharge specific capacity of 1142.2 mAh g^-1 and capacity attenuation of 0.0617% per cycle can be obtained at 1C.

Understanding the interactions between lithium polysulfides and anchoring materials in advanced lithium-sulfur batteries using density functional theory

Lithium-sulfur batteries (LSBs) are promising energy storage devices because of their high theoretical capacity and energy density. However, the "shuttle" effect in lithium polysulfides (LiPSs) is an unresolved issue that can hinder their practical commercial application. Research on LSBs has focused on finding appropriate materials that suppress this effect by efficiently anchoring the LiPSs intermediates. Quantum chemical computations are a useful tool for understanding the mechanistic details of chemical interaction involving LiPSs, and they can also offer strategies for the rational design of LiPSs anchoring materials. In this perspective, we highlight computational and theoretical work performed on this topic. This includes elucidating and characterizing the adsorption mechanisms, and the dominant types of interactions, and summarizing the binding energies of LiPSs on anchoring materials. We also give examples and discuss the potential of descriptors and machine learning approaches to predict the adsorption strength and reactivity of materials. We believe that both approaches will become indispensable in modelling future LSBs.

Hierarchical MoxC @ NC Hollow Microsphere with Incorporated Mo Vacancies as Multifunctional Confined Reactors for High-loading Li-S Batteries

The undesirable notorious shuttling of lithium polysulfides (LiPSs) and sluggish redox kinetic lead to the serious cycle life and reduce the sulfur utilization. Herein, to tackle these problems simultaneously, a...

Isolated Single-Atom Ni-N5 Catalytic Site in Hollow Porous Carbon Capsules for Efficient Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries suffer from multiple complex and often interwoven issues, such as the low electronic conductivity of sulfur and Li₂S/Li₂S₂, shuttle effect, and sluggish electrochemical kinetics of lithium polysulfides (LiPSs). Guided by theoretical calculations, a multifunctional catalyst of isolated single-atom nickel in an optimal Ni-N₅ active moiety incorporated in hollow nitrogen-doped porous carbon (Ni-N₅/HNPC) is constructed and acts as an ideal host for a sulfur cathode. The host improved electrical conductivity, enhanced physical-chemical dual restricting capability toward LiPSs, and, more importantly, boosted the redox reaction kinetics by the Ni-N₅ active moiety. Therefore, the Ni-N₅/HNPC/S cathode exhibits superior rate performance, long-term cycling stability, and good areal capacity at high sulfur loading. This work highlights the important role of the coordination number of active centers in single-atom catalysts and provides a strategy to design a hollow nanoarchitecture with single-atom active sites for high-performance Li-S batteries.

Efficient toluene adsorption/desorption on biochar derived from in situ acid-treated sugarcane bagasse

Carbon-based materials with great adsorption performance are of importance to meet the needs of industrial gas adsorption. Having massive agricultural wastes of sugarcane bagasse, China could use this waste into wealth. However, the comprehensive utilization of sugarcane bagasse as precursor for biochar that can be used as adsorbent has not been extensively explored. In this study, a series of in situ sulfuric acid-modified biochar was prepared by hydrothermal carbonization process. The prepared biochar (SBAC-7) has a combination of two main advantages that are high microporosity (micropore surface area = 1106 m2/g) and being rich in S-containing functional groups on the surface. In particular, SBAC-7 showed an excellent adsorption capacity of toluene (771.1 mg/g) at 30 °C, which is nearly 3 times as high as that of the commercial activated carbons. Meanwhile, it showed great stability and cyclic regeneration performance with five toluene adsorption-desorption test cycles. This study provides a high-performance biochar for the adsorption-desorption cycle in practical engineering applications, and would contribute to the sustainable "sugarcane production-bagasse utilization" circular economy.

Vanadium Nitride Quantum Dots/Holey Graphene Matrix Boosting Adsorption and Conversion Reaction Kinetics for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) have been considered as potential next-generation energy storage systems due to their high specific energy of 2600 Wh kg^-1 and 2800 Wh L^-1. Nevertheless, the practical application of LSBs still faces several hazards, including the shuttle effect of soluble lithium polysulfides, low electrical conductivities of solid sulfur and lithium sulfides, and large volume expansion during charge/discharge cycles. To address this critical challenge, we innovatively proposed facile synthesis of nanostructured VN quantum dots (VNQD)/holey graphene matrix for stabilizing the sulfur cathode by simultaneously promoting the trapping, anchoring, and catalyzing efficiencies of both LiPSs and Li₂S. Benefiting from abundant edge catalytic sites of VNQD, in-plane nanopores of graphene, and high electrical conductivity, the sulfur host not only provides high adsorption capability toward soluble polysulfides, strong binding ability for anchoring solid Li₂S, and their rapid conversion kinetics but also contributes abundant sulfur storage sites and efficient transport pathways for lithium ions (Li⁺) and electrons. Consequently, the sulfur cathode exhibits high initial capacities of 1320 mAh g^-1, high rate capability (850 mAh g^-1 @ 4 mA cm^-2), and high capacity retention of 99.95% per cycle after 500 cycles, providing a feasible solution for the practical utilization of shuttle-free Li-S batteries.

Implanting Cobalt Atom Clusters within Nitrogen-Doped Carbon Network as Highly Stable Cathode for Lithium-Sulfur Batteries

Realization of highly efficient sulfur electrochemistry, as well as the high capacity of lithium-sulfur (Li-S) batteries, can be achieved by the scientific construction of electrode host materials. In this study, using molten NaCl, a 3D porous nitrogen-doped carbon with uniformly embedded Co atom clusters (Co/PNC) is developed by pyrolyzing the precursors with NaCl at high temperatures. In the composite structure, a network carbon skeleton containing hierarchical pores acts as an advanced matrix for sulfur electrodes, and the doping of N and Co is subject to inhibit the shuttle of long-chain lithium polysulfides through chemical adsorption. The Co/PNC, with the optimized amount of Co, delivers an initial specific capacity of 1105.4 mAh g^-1 at 0.2 C with a capacity drop of only 0.064% after the cell is charged and discharged for 300 cycles at 1 C, revealing its potential in promoting the large-scale application of Li-S batteries.

A novel highly dispersed tetra-metal nano heterogeneous ozone catalyst derived from microbial adsorption and in situ pyrolysis

In recent years, the pyrolysis of microbial biomasses that adsorb various metal ions has enabled the preparation of carbon-based polymetallic nanomaterials with excellent electrocatalytic and electrical energy storage properties. However, the preparation of ozone catalysts by this technique and the corresponding catalytic oxidation mechanism are still unclear. In this study, an Escherichia coli strain (BL21) was used for tetra-metal (Cu, Fe, Mn and Al) absorption and the obtained microbial biomass was pyrolyzed under the protection of a nitrogen flow at 700 °C and activated at 900 °C to prepare a microbial-char-based tetra-metal ozone catalyst (MCOC). This was used to degrade phenol and coking wastewater and exhibited a strong catalytic capability for coking wastewater, whose chemical oxygen demand removal efficiency of 70.86% is 16.7% higher than that of pure ozone and 14.67%, 7.21% and 3.58% higher than that of three commercial catalysts, respectively. It also improved the efficiency of ozonation for phenol by 33%. The MCOC was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive spectroscopy, transmission electron microscopy and other methods. The results demonstrated that the spherical metal nanoparticles had sizes ranging from 3 nm to 7 nm and that crystals of Fe₂O₃ and Fe₃P were observed. The study showed that the MCOC promoted the production of more hydroxyl radicals and superoxides from ozone, which attack organics. The oxygen vacancies of the catalyst were also investigated. It was proved that the Lewis acid sites on the surface of metal oxides are the active centers of ozone decomposition. Therefore, this work provides a new method for the synthesis of multi-metal nanocomposites and expands the application of biosynthetic nanomaterials.

Flexible pore structure modulation enables durable sulfur carrier for advanced lithium–sulfur batteries

The immobilization of polysulfide by carbon matrix via synergism can restrict the shuttle effect and extend the cycle life of Li–S batteries.

Single-atom Catalytic Materials for Lean-electrolyte Ultrastable Lithium-Sulfur Batteries

Lithium-sulfur batteries with high energy capacity are promising candidates for advanced energy storage. However, their applications are impeded by shuttling of soluble polysulfides and sluggish conversion kinetics with inferior rate performance and short cycling life. Here, single-atom materials are designed to accelerate polysulfide conversion for Li-S batteries. Nitrogen sites in the structure not only anchor polysulfides to alleviate the shuttle effect but also enable high loading of single-atom irons. Density functional theory calculations indicate that single-atom sites reduce the energy barrier of electrochemical reactions and thus improve the rate and cycling performances of batteries. The coin battery shows impressive energy storage properties, including a high reversible capacity of 1379 mAh g^-1 at 0.1 C and a high rate capacity of 704 mAh g^-1 at 5 C. The ratio of electrolyte dosage/energy density is as low as 5.5 g Ah^1-. It exhibits excellent cycling performance with a capacity retention of 90% even after 200 cycles at 0.2 C.

Hierarchical porous carbon fabricated from cellulose-degrading fungus modified rice husks: Ultrahigh surface area and impressive improvement in toluene adsorption

The porous carbon materials formed from biomass precursors are promising candidates for adsorbing organic vapor pollutants. However, these materials have insufficient pores, which hinder their accessibility to adsorbates. This study develops an ultrahigh-surface-area porous carbon adsorbent with interlacing micro-mesoporous structures through Trichoderma viride decomposition. An orthogonal experiment is conducted, and the most suitable conditions for fabricating porous carbon with an ultrahigh S_BET of 3714 m².g^-1 and a hierarchical porous structure are identified. This work achieves one of the highest specific surface areas of biomass carbons among recent studies. T. viride corrodes the internal and external microstructures of rice husks, and regulates the lignin, cellulose, and hemicellulose contents, which improve the efficiency of carbonization and chemical activation. The carbonaceous materials with microbial pretreatment exhibit better toluene adsorption performances (100 ppm: 708 mg.g^-1), adsorption rates, and cyclic utilization than those without pretreatment (100 pm: 538 mg.g^-1). In addition, grand canonical Monte Carlo simulation is conducted. The micropores and mesopores created after microbial pretreatment are effective toluene adsorption sites. Moreover, the diffusion coefficient calculated by utilizing Thomas model and Chemical diffusion verify that the mesopores accelerate the kinetic process of toluene adsorption.

Self-Phosphorization of MOF-Armored Microbes for Advanced Energy Storage

Utilization of microbes as the carbon source and structural template to fabricate porous carbon has incentivized great interests owing to their diverse micromorphology and intricate intracellular structure, apart from the obvious benefit of "turning waste into wealth." Challenges remain to preserve the biological structure through the harsh and laborious post-synthetic treatments, and tailor the functionality as desired. Herein, Escherichia coli is directly coated with metal-organic frameworks (MOFs) through in situ assembly to fabricate N, P co-doped porous carbon capsules expressing self-phosphorized metal phosphides. While the MOF coating serves as an armoring layer for facilitating the morphology inheritance from the bio-templates and provides metal sources for generating extra porosity and electrochemically active sites, the P-rich phospholipids and N-rich proteins from the plasma membrane enable carbon matrix doping and further yield metal phosphides. These unique structural and compositional features endow the carbon capsules with great capabilities in suppressing polysulfide shuttling and catalyzing reversible oxygen conversion, ultimately leading to the superb performance of lithium-sulfur batteries and zinc-air batteries. Combining the bio-templating strategy with hierarchical MOF assembly, this work opens a new avenue for the fabrication of highly porous and functional carbon for advanced energy applications.

High loading cotton cellulose-based aerogel self-standing electrode for Li-S batteries

Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their high energy density (2600 Wh kg^-1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulfur cathodes. Herein, we designed the cellulose-based graphene carbon composite aerogel (CCA) self-standing electrode to enhance the performance of Li-S batteries. The CCA contributes to the mass loading and utilization efficiency of sulfur, because of its unique physical structure: low density (0.018 g cm^-3), large specific surface area (657.85 m² g^-1), high porosity (96%), and remarkable electrolyte adsorption (42.25 times). Compared to Al (about 49%), the CCA displayed excellent sulfur use efficiency (86%) and could reach to high area capacity of 8.60 mAh cm^-2 with 9.11 mg S loading. Meanwhile, the CCA exhibits the excellent potential for pulse sensing applications due to its flexibility and superior sensitivity to electrical response signals.

Covalent sulfur embedding in inherent N,P co-doped biological carbon for ultrastable and high rate lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are attracting extensive interest owing to their low cost and potential for applications in high-density energy storage systems. However, their widespread application is severely plagued by poor cycling stability, inferior rate capability and low coulombic efficiency, which are largely attributed to the shuttling effect of soluble polysulfides. Herein, we report an architecture of an N,P co-doped biological carbon-based covalent sulfur composite (NP@BCCSC), which acts as a cathode for highly robust Li-S batteries. The NP@BCCSC can not only buffer the volume expansion of sulfur during the charge/discharge process, but also shows strong absorption towards soluble polysulfides, which can effectively suppress the shuttling effect. As a cathode for Li-S batteries, the NP@BCCSC with a sulfur content of 20.1% exhibits a reversible capacity of 1190 mA h g-1 (all specific capacities are calculated based on the mass of sulfur) at a current density of 500 mA g-1 after 500 cycles with an average coulombic efficiency of approximately 100%. Moreover, the NP@BCCSC offers a highly robust cycling stability (an ultralow capacity fading rate of 0.0024% per cycle during 15 000 consecutive cycles) and an excellent rate capability (high specific capacity of 920 mA h g-1 even at a current density of 10 000 mA g-1), indicating its great potential for applications in future energy storage systems.

Two-Dimensional MoS2 for Li-S Batteries: Structural Design and Electronic Modulation

Two-dimensional molybdenum disulfide (MoS₂ ) nanosheets attract great interest for applications in lithium-sulfur (Li-S) batteries, due to their unique physical and chemical properties, which originate from diverse chemical compositions and unique electronic structures. In recent years, many efforts have been devoted to employing MoS₂ as a polysulfide immobilizer and catalyst, functional separator, and Li-metal protection for Li-S batteries through structural design and electronic modulation. A fundamental understanding of the interplay between structural features, electronic properties, and advanced electrochemical performance is crucial for providing valuable insights for the development of Li-S batteries. In this regard, recent advances in Li-S batteries with 2D MoS₂ materials are summarized from the perspective of structural design and electronic modulation. Finally, future prospects and remaining challenges of MoS₂ for Li-S batteries are highlighted.

Covalent Selenium Embedded in Hierarchical Carbon Nanofibers for Ultra-High Areal Capacity Li-Se Batteries

Lithium selenium (Li-Se) batteries have attracted increasing interest for its high theoretical volumetric capacities up to 3,253 Ah L⁻¹. However, current studies are largely limited to electrodes with rather low mass loading and low areal capacity, resulting in low volumetric performance. Herein, we report a design of covalent selenium embedded in hierarchical nitrogen-doped carbon nanofibers (CSe@HNCNFs) for ultra-high areal capacity Li-Se batteries. The CSe@HNCNFs provide excellent ion and electron transport performance, whereas effectively retard polyselenides diffusion during cycling. We show that the Li-Se battery with mass loading of 1.87 mg cm⁻² displays a specific capacity of 762 mAh g⁻¹ after 2,500 cycles, with almost no capacity fading. Furthermore, by increasing the mass loading to 37.31 mg cm⁻², ultra-high areal capacities of 7.30 mAh cm⁻² is achieved, which greatly exceeds those reported previously for Li-Se batteries.

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The CSe@HNCNFs were used as flexible and free-standing cathode for Li-Se battery

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The CSe@HNCNFs effectively retard polyselenides diffusion during cycling

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The CSe@HNCNFs delivered high areal capacity of 7.30 mAh cm⁻²

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The CSe@HNCNFs displayed excellent cyclic stability and rate performance

A germanium and zinc chalcogenide as an anode for a high-capacity and long cycle life lithium battery

High-performance lithium ion batteries are ideal energy storage devices for both grid-scale and large-scale applications. Germanium, possessing a high theoretical capacity, is a promising anode material for lithium ion batteries, but still faces poor cyclability due to huge volume changes during the lithium alloying/dealloying process. Herein, we synthesized an amorphous germanium and zinc chalcogenide (GZC) with a hierarchically porous structure via a solvothermal reaction. As an anode material in a lithium ion battery, the GZC electrode exhibits a high reversible capacity of 747 mA h g-1 after 350 cycles at a current density of 100 mA g-1 and a stable capacity of 370 mA h g-1 after 500 cycles at a current density of 1000 mA g-1 along with 92% capacity retention. All of these outstanding electrochemical properties are attributed to the hierarchically porous structure of the electrode that has a large surface area, fast ion conductivity and superior structural stability, which buffers the volumetric variation during charge/discharge processes and also makes it easier for the electrolyte to soak in, affording more electrochemically active sites.