Gifts from Nature: Bio-Inspired Materials for Rechargeable Secondary Batteries

Deriving Superhydrophobicity Directly and Solely from Molecules: A Facile and Emerging Approach

Nature-inspired superhydrophobic surfaces have gained significant attention due to their various potential applications. Artificial superhydrophobic surfaces were fabricated through co-optimization of topography and low-surface-energy chemistry. In the conventional approach, artificial superhydrophobic surfaces are developed through associating mostly polymer, metal, alloys, nanoparticles, microparticles, etc. and commonly encounter several challenges related to scalability, durability, and complex fabrication processes. In response to these challenges, molecule-based approaches have emerged as a promising alternative, providing several advantages such as prolonged shelf life of depositing solution, higher solvent compatibility, and a simple fabrication process. In this Perspective, we have provided a concise overview of traditional and molecule-based approaches to fabricating superhydrophobic surfaces, highlighting recent advancements and challenges. We have discussed various molecule-based strategies for tailoring water wettability, customizing mechanical properties, developing substrate-independent coatings, prolonging the shelf life of deposition solutions, and so on. Here, we have illustrated the potential of molecule-based approaches in overcoming existing limitations and its importance to diverse and prospective practical applications.

Enzyme-Enabled Droplet Biobattery for Powering Synthetic Tissues

Enzyme-enabled biobatteries are promising green options to power the next-generation of bioelectronics and implantable medical devices. However, existing power sources based on enzymatic biofuel chemistry exhibit limited scale-down feasibility due to the solid and bulky battery structures. Therefore, miniature and soft alternatives are needed for integration with implants and tissues. Here, a biobattery built from nanolitre droplets, fuelled by the enzyme-enabled oxidation of reduced nicotinamide adenine dinucleotide, generates electrical outputs and powers ion fluxes in droplet networks. Optimization of the droplet biobattery components ensures a stable output current of ~13,000 pA for over 24 h, representing a more than 600-fold increase in output over previous approaches, including light-driven processes. The enzyme-enabled droplet biobattery opens new avenues in bioelectronics and bioiontronics, exemplified by tasks such as the ability to drive chemical signal transmission in integrated synthetic tissues.

Achievements, challenges, and perspectives in the design of polymer binders for advanced lithium-ion batteries

Energy storage devices with high power and energy density are in demand owing to the rapidly growing population, and lithium-ion batteries (LIBs) are promising rechargeable energy storage devices. However, there are many issues associated with the development of electrode materials with a high theoretical capacity, which need to be addressed before their commercialization. Extensive research has focused on the modification and structural design of electrode materials, which are usually expensive and sophisticated. Besides, polymer binders are pivotal components for maintaining the structural integrity and stability of electrodes in LIBs. Polyvinylidene difluoride (PVDF) is a commercial binder with superior electrochemical stability, but its poor adhesion, insufficient mechanical properties, and low electronic and ionic conductivity hinder its wide application as a high-capacity electrode material. In this review, we highlight the recent progress in developing different polymeric materials (based on natural polymers and synthetic non-conductive and electronically conductive polymers) as binders for the anodes and cathodes in LIBs. The influence of the mechanical, adhesion, and self-healing properties as well as electronic and ionic conductivity of polymers on the capacity, capacity retention, rate performance and cycling life of batteries is discussed. Firstly, we analyze the failure mechanisms of binders based on the operation principle of lithium-ion batteries, introducing two models of "interface failure" and "degradation failure". More importantly, we propose several binder parameters applicable to most lithium-ion batteries and systematically consider and summarize the relationships between the chemical structure and properties of the binder at the molecular level. Subsequently, we select silicon and sulfur active electrode materials as examples to discuss the design principles of the binder from a molecular structure point of view. Finally, we present our perspectives on the development directions of binders for next-generation high-energy-density lithium-ion batteries. We hope that this review will guide researchers in the further design of novel efficient binders for lithium-ion batteries at the molecular level, especially for high energy density electrode materials.

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Review: Application of Bionic-Structured Materials in Solid-State Electrolytes for High-Performance Lithium Metal Batteries

Solid-state lithium metal batteries (SSLMBs) have gained significant attention in energy storage research due to their high energy density and significantly improved safety. But there are still certain problems with lithium dendrite growth, interface stability, and room-temperature practicality. Nature continually inspires human development and intricate design strategies to achieve optimal structural applications. Innovative solid-state electrolytes (SSEs), inspired by diverse natural species, have demonstrated exceptional physical, chemical, and mechanical properties. This review provides an overview of typical bionic-structured materials in SSEs, particularly those mimicking plant and animal structures, with a focus on their latest advancements in applications of solid-state lithium metal batteries. Commencing from plant structures encompassing roots, trunks, leaves, flowers, fruits, and cellular levels, the detailed influence of biomimetic strategies on SSE design and electrochemical performance are presented in this review. Subsequently, the recent progress of animal-inspired nanostructures in SSEs is summarized, including layered structures, surface morphologies, and interface compatibility in both two-dimensional (2D) and three-dimensional (3D) aspects. Finally, we also evaluate the current challenges and provide a concise outlook on future research directions. We anticipate that the review will provide useful information for future reference regarding the design of bionic-structured materials in SSEs.

Electric Eel Biomimetics for Energy Storage and Conversion

The electric eel is known as the most powerful creature to generate electricity with a discharge voltage up to 860 V and peak current up to 1 A. These surprising properties are the results of billions of years of evolution on the electrical biological structure and bulk, and now have triggered great research interest in electric eel biomimetics for designing innovated configurations and components of energy storage and conversion devices. In this review, first, the bioelectrical behavior of electric eels is surveyed, followed by the physiological structure to reveal the discharge characteristics and principles of electric organs and electrocytes. Additionally, underlying electrochemical mechanisms and models for calculating the potential and current of electrocytes are presented. Central to this review is the recent progress of electric-eel-inspired innovations and applications for energy storage and conversion, particularly including novel power sources, triboelectric nanogenerators, and nanochannel ion-selective membranes for salinity gradient energy harvesting. Finally, insights on the challenges at the moment and the perspectives on the future research prospects are critically compiled. It is suggested that energy-related electric eel biomimetics will greatly boost the development of next-generation high performance, green, and functional electronics.

Biomimetic-Mineralization-Assisted Self-Activation Creates a Delicate Porous Structure in Carbon Material for High-Rate Sodium Storage

Porous carbons have shown their potential in sodium-ion batteries (SIBs), but the undesirable initial Coulombic efficiency (ICE) and rate capability hinder their practical application. Herein, learning from nature, we report an efficient method for fabricating a carbon framework (CK) with delicate porous structural regulation by biomimetic mineralization-assisted self-activation. The abundant pores and defects of the CK anode can improve the ICE and rate performance of SIBs in ether-based electrolytes, whereas they are confined in carbonate ester-based electrolytes. Notably, ether-based electrolytes enable CK anode to possess excellent ICE (82.9%) and high-rate capability (111.2 mAh g-1 at 50 A g-1). Even after 5500 cycles at a large current density of 10 A g-1, the capacity retention can still be maintained at 73.1%. More importantly, the full cell consisting of the CK anode and Na3V2(PO4)3 cathode delivers a high energy density of 204.4 Wh kg-1, with a power density of 2828.2 W kg-1. Such outstanding performance of the CK anode is attributed to (1) hierarchical pores, oxygen doping, and defects that pave the way for the transportation and storage of Na+, further enhancing ICE; (2) a high-proportion NaF-based solid-electrolyte-interphase (SEI) layer that facilitates Na+ storage kinetics in ether-based electrolytes; and (3) ether-based electrolytes that determine Na+ storage kinetics further to dominate the performance of SIBs. These results provide compelling evidence for the promising potential of our synthetic strategy in the development of carbon-based materials and ether-based electrolytes for electrochemical energy storage.

Bio-inspired carbon electrodes for metal-ion batteries

Carbon has been widely used as an electrode material in commercial metal-ion batteries (MIBs) because of its desirable electrical, mechanical, and physical properties. Still, traditional carbon electrodes suffer from limited mechanical stability and electrochemical performance in MIBs. Drawing inspiration from biological species, the carbon allotropes, such as fullerenes, carbon nanotubes, and graphene, can be engineered into mechanically robust, highly conductive frameworks with enhanced ion storage and transport capabilities for MIBs. Here, we present an assortment of bio-inspired carbon electrodes that have enhanced the cycling stability, capacity retention, and overall performance of MIBs. In addition, mimicking the structure and functionality of biological systems has led to the development of flexible MIBs whose performance does not degrade even when stretched, bent, or twisted. Finite element analysis (FEA) is a useful guide in identifying such bio-inspired carbon frameworks because it can simulate and analyze potential failure scenarios, such as stress build-up or structural collapse in MIBs. This review highlights through several examples that there is much scope for improving carbon-based electrode materials through bio-inspired designs for practical high-performance MIBs.

Study on the Construction of Interlayer Adjustable C@MoS2 Fiber Anode by Biomass Confining and its Lithium/Sodium Storage Mechanism

Building a stable and controllable interlayer structure is the key to improving the sodium storage cycling stability and rate performance of two-dimensional anode materials. This study explored the rich functional groups in bacterial cellulose culture medium in the way of biological self-assembly. Mo precursors were used to produce chemical bond in bacterial cellulose culture medium, and intercalation groups are introduced to achieve MoS2 localized nucleation and in situ localized construction of carbon intercalation stable interlaminar structure, thus improving ion transport dynamics and cycle stability. In order to avoid structural irreversibility of MoS2 at low potential, an extended voltage window of 1.5-4 V was selected for lithium/sodium intercalation testing. It was found that there was a significant improvement in sodium storage capacity and stability. During the electrochemical cycling process, in-situ Raman testing revealed that the structure of MoS2 was completely reversible, and the intensity changes of MoS2 characteristic peaks showed in-plane vibration without involving interlayer bonding fracture. Moreover, after the lithium sodium was removed from the intercalation C@MoS2 all structures have good retention.

Design of Bifunctional Nanocatalysts Based on Zeolites for Biomass Processing

Bifunctional catalysts consisting of metal-containing nanoparticles (NPs) and zeolite supports have received considerable attention due to their excellent catalytic properties in numerous reactions, including direct (biomass is a substrate) and indirect (platform chemical is a substrate) biomass processing. In this short review, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods that allow for the best interplay (synergy) between metal and acid sites, which is normally achieved for small NPs well-distributed through zeolite. We focus on the modification of zeolites to provide structural integrity and controlled acidity, which can be accomplished by the incorporation of certain metal ions or elements. The other modification avenue is the adjustment of zeolite morphology, including the creation of numerous defects for the NP entrapment and designed hierarchical porosity for improved mass transfer. In this review, we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations, many assumptions about the interactions between active sites remain unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years.

Self-Assembled Protein Nanofilm Regulating Uniform Zn Nucleation and Deposition Enabling Long-Life Zn Anodes

Rechargeable zinc-ion batteries (RZIBs) have gained promising attention as a feasible alternative for large-scale energy storage by the virtue of their intrinsic security, environmental benignity, low cost, and high volumetric capacity (5849 mAh cm-3 ). Nevertheless, the deep-rooted issues of dendrite formation and side reactions in unstable Zn metal anode have impeded RZIBs from being dependably deployed in their proposed applications. Herein, silk fibroin (SF) and lysozyme (ly), as natural biomacromolecules with abundant polar groups arranged in polypeptide backbones, are in situ self-assembled on the Zn anode surface to construct a homogeneous and compact protein nanofilm. Such protein nanofilm protecting layer presents a negative charge surface and significantly regulates Zn2+ deposition behavior. Meanwhile, synergistic flexible and robust features of protein nanofilm function as artificial solid electrolyte interface (SEI), accommodates the dynamic volume deformation during deposition/dissolution, and blocks corrosion of side reactions. Consequently, the electrochemical stability of protein nanofilm-modified Zn anode is greatly improved, with an excellent extended lifespan of over 1100 h at a high current density of 10 mA cm-2 and a high cycling capacity of 10 mAh cm-2 , corresponding to a high depth of discharge (83% DODZn ). Furthermore, the highly reversible Zn electrode remarkably improved the overall performance of MnO2 ||Zn full-cells.

Fabricating biomimetic materials with ice-templating for biomedical applications

The proper organization of cells and tissues is essential for their functionalization in living organisms. To create materials that mimic natural structures, researchers have developed techniques such as patterning, templating, and printing. Although these techniques own several advantages, these processes still involve complexity, are time-consuming, and have high cost. To better simulate natural materials with micro/nanostructures that have evolved for millions of years, the use of ice templates has emerged as a promising method for producing biomimetic materials more efficiently. This article explores the historical approaches taken to produce traditional biomimetic structural biomaterials and delves into the principles underlying the ice-template method and their various applications in the creation of biomimetic materials. It also discusses the most recent biomedical uses of biomimetic materials created via ice templates, including porous microcarriers, tissue engineering scaffolds, and smart materials. Finally, the challenges and potential of current ice-template technology are analyzed.

Rough Endoplasmic Reticulum Inspired Polystyrene-Brush-Based Superhigh Sulfur Content Cathodes Enable Lithium-Sulfur Cells with High Mass and Capacity Loading

The development of highly sophisticated biomimetic models is significant yet remains challenging in the electrochemical energy storage field. Lithium-sulfur (Li-S) cells with high sulfur content and high-sulfur-loading cathodes are urgently required to meet the fast-growing demand for electronic devices. Nevertheless, such cathode materials generally suffer from large sulfur agglomeration, nonporous structure, and insufficient conductivity, leading to rapid capacity decay and low sulfur utilization. Herein, inspired by rough endoplasmic reticulum, a 2D polystyrene (PS)-brush-based (G-g-PS) superhigh-sulfur-content (96 wt%) composite(G-g-sPS@S) is fabricated via the vulcanization reaction. The vulcanized PS side-chains and their S₈ composites on the nanosheet surface can efficiently provide sulfur species, and the intersheet interstitial pores can provide rapid mass-transfer channels for redox reactions of sulfur species. Furthermore, the highly sulfophilic vulcanized PS side-chains are able to effectively inhibit the shuttle effect of polysulfides and regulate their redox process. With these merits, the cells with G-g-sPS@S cathodes exhibit an ultralow decay rate of 0.02% per cycle over 400 cycles at 2 C and deliver a superior areal capacity of 12.6 mAh cm^-2 even with a high sulfur loading of 10.5 mg cm^-2 .

Engineering Polymeric Nanofluidic Membranes for Efficient Ionic Transport: Biomimetic Design, Material Construction, and Advanced Functionalities

Design elements extracted from biological ion channels guide the engineering of artificial nanofluidic membranes for efficient ionic transport and spawn biomimetic devices with great potential in many cutting-edge areas. In this context, polymeric nanofluidic membranes can be especially attractive because of their inherent flexibility and benign processability, which facilitate massive fabrication and facile device integration for large-scale applications. Herein, the state-of-the-art achievements of polymeric nanofluidic membranes are systematically summarized. Theoretical fundamentals underlying both biological and synthetic ion channels are introduced. The advances of engineering polymeric nanofluidic membranes are then detailed from aspects of structural design, material construction, and chemical functionalization, emphasizing their broad chemical and reticular/topological variety as well as considerable property tunability. After that, this Review expands on examples of evolving these polymeric membranes into macroscopic devices and their potentials in addressing compelling issues in energy conversion and storage systems where efficient ion transport is highly desirable. Finally, a brief outlook on possible future developments in this field is provided.

Ultrastable Bioderived Organic Anode Induced by Synergistic Coupling of Binder/Carbon-Network for Advanced Potassium-Ion Storage

Bioderived molecules have been identified as viable anodes for organic potassium-ion batteries (OPIBs) due to the abundance of the necessary natural resources, their high capacity, and their sustainability. However, the high solubility and the inherent nonconductivity cause serious capacity decay and large voltage hysteresis. Here, the biomass molecule juglone was cross-linked with a carbon nanotube network, coupling and cooperating with sodium alginate binder (J@CNT-SA), and was proposed to inhibit small molecule dissolution via weak intermolecular interactions. The synergistic effect of hydrogen bonding and π-π stacking is proven for its outstanding reversible high capacities (262 mA h g^-1 at 0.05 A g^-1), and a remarkable long life span with capacity retention of 77% over 5000 cycles. Further in situ Fourier transform infrared spectroscopy (FTIR) was performed to reveal the electrochemical mechanism. The feasibility of juglone as an anode for PIBs paves the way for other natural organic small molecules to be investigated as potential energy storage materials.

B, O and N Codoped Biomass-Derived Hierarchical Porous Carbon for High-Performance Electrochemical Energy Storage

High specific surface area, reasonable pore structure and heteroatom doping are beneficial to enhance charge storage, which all depend on the selection of precursors, activators and reasonable preparation methods. Here, B, O and N codoped biomass-derived hierarchical porous carbon was synthesized by using KCl/ZnCl2 as a combined activator and porogen and H3BO3 as both boron source and porogen. Moreover, the cheap, environmentally friendly and heteroatom-rich laver was used as a precursor, and impregnation and freeze-drying methods were used to make the biological cells of laver have sufficient contact with the activator so that the layer was deeply activated. The as-prepared carbon materials exhibit high surface area (1514.3 m2 g−1), three-dimensional (3D) interconnected hierarchical porous structure and abundant heteroatom doping. The synergistic effects of these properties promote the obtained carbon materials with excellent specific capacitance (382.5 F g−1 at 1 A g−1). The symmetric supercapacitor exhibits a maximum energy density of 29.2 W h kg−1 at a power density of 250 W kg−1 in 1 M Na2SO4, and the maximum energy density can reach to 51.3 W h kg−1 at a power density of 250 W kg−1 in 1 M BMIMBF4/AN. Moreover, the as-prepared carbon materials as anode for lithium-ion batteries possess high reversible capacity of 1497 mA h g−1 at 1 A g−1 and outstanding cycling stability (no decay after 2000 cycles).

Transition Metal Engineering of Molybdenum Disulfide Nanozyme for Biomimicking Anti-Biofouling in Seawater

Nature has evolved diverse strategies to battle surface biofouling colonization and thus provides us novel insights into designing and developing advanced nontoxic antibiofouling materials and technologies. Mimicking the defense mechanisms of natural haloperoxidases in marine algae in response to biofilm colonization, here we show that the less active MoS₂ shows efficient haloperoxidase-mimicking activity through judicious transition metal engineering. Cobalt-doped MoS₂ (Co-MoS₂) displays an excellent haloperoxidase-mimicking performance in catalyzing the Br^- oxidation into germicidal HOBr, roughly 2 and 23 times higher than the nickel-doped MoS₂ and pristine MoS₂, respectively. Accordingly, Co-MoS₂ shows an outstanding antimicrobial effect against drug-resistant bacteria and antibiofouling performance in real field tests in marine environments. The realization of robust haloperoxidase-mimicking activity of MoS₂ via metal engineering may open a new avenue to design highly active transition metal dichalcogenides for antibacterial and antibiofouling applications.