Next-generation Rechargeable Batteries Research Articles

La2MoO6 as an Effective Catalyst for the Cathode Reactions of Lithium-Sulfur Batteries.

Lithium-sulfur batteries with high theoretical energy density have emerged as one of the most promising next-generation rechargeable batteries, while their discharge capacity and cycle stability are challenges mainly due to the shuttle effect of polysulfide intermediates. Employing an effective catalyst for the conversion of polysulfides in cathode reactions can promote the reaction kinetics to restrain the shuttle of polysulfides. Here, for the first time, La2MoO6 (LMO) as a catalyst is introduced into sulfur cathodes. To investigate the effect of La2MoO6, we prepare two different structures of La2MoO6/carbon nanofiber composites. One is carbon nanofiber-supported crystalline La2MoO6 nanoparticles (LMO@CNFs) and the other is amorphous La2MoO6 nanoparticles embedded in carbon nanofibers (LMO-in-CNFs). For sulfur electrodes with ∼73 wt % sulfur loading, LMO@CNFs/S and LMO-in-CNFs/S deliver initial gravimetric capacities of 1493.4 and 1246.7 mA h g-1, respectively, at a 0.1C rate, obviously higher than that of the control sample CNFs/S. Moreover, LMO@CNFs/S shows much better rate performance than LMO-in-CNFs/S, indicating strongly that La2MoO6 is a highly effective catalyst to promote kinetic conversion of polysulfides.

Dual-layer vermiculite nanosheet based hybrid film to suppress dendrite growth in lithium metal batteries

Lithium metal anode has become a favorable candidate for next-generation rechargeable batteries. However, the unstable interface between lithium metal and electrolyte leads to the growth of dendrites, resulting in the low Coulombic efficiency and even the safety concerns. Herein, a rigid-flexible dual-layer vermiculite nanosheet (VN) based organic-inorganic hybrid film on lithium metal anode is proposed to suppress dendrite growth and relieve volume fluctuations. The inner mechanically robust VN layer (3 μm thick) enhances the mechanical properties of the protective layer, while the outer polymer (4 μm thick) can enhance the flexibility of the hybrid layer. The Li | Li symmetric cell with protected lithium shows an extended life of over 670 h. The full cell with Li anode protected by dual-layer interface exhibits a better capacity retention of 80% after 174 cycles in comparison to bare Li anode with 94 cycles. This study provides a novel approach and a significant step towards prolonging lifespan of lithium metal batteries.

A gradient topology host for a dendrite-free lithium metal anode

Lithium metal is a “holy grail” anode (LMA) for next-generation rechargeable batteries. However, the uncontrollable growth of Li dendrites and infinite volume change plague their practical applications. Herein, we propose a 3D topological host as a stable LMA, which is realized by gradient decoration of carbon cloth with SiC whiskers (SiC/CC). The gradient distribution of SiC whiskers leads to a gradient electric field and induces a bottom-up lithium deposition process. The symmetric cell with a Li@SiC/CC LMA exhibits a low overpotential up to 1000 h at 2 mA cm−2 with a capacity of 3 mA h cm−2. An average Coulombic efficiency of as high as 98.3% is remained in the full cell even after 100 cycles with a capacity of 3 mA h cm−2. Experimental and calculation results demonstrate that such a knitted network increases the utilization of the host and further suppresses the dendrite growth during plating. Moreover, this topological host reduces the local size of Li deposits and alleviates their detachment to form “dead Li” during the stripping process. This novel strategy offers a straightforward approach to construct a gradient topological host for reliable LMAs with high energy densities.

Increasing ionic conductivity in polymer electrodes using oxanorbornene

AbstractPendant polymer‐based organic electrodes consisting of redox‐active quinones are promising for the next generation of rechargeable batteries owing to their fast redox kinetics and the structural diversity of their design. Many commercially available norbornene monomers have been popular choices for preparing pendant polymer electrodes, since these monomers enable numerous synthetic routes for attaching redox‐active pendant groups. However, these electrodes often suffer from sluggish lithium‐ion mobility at both the electrode–electrolyte interface and within the bulk of the electrode because of their poor ionic conductivity. This can lead to low cycling stability and rate capability. In this study, we design and compare the performance of redox‐active poly(norbornene) and poly(oxanorbornene) pendant polymer electrodes. The additional oxygen in the repeat unit of poly(oxanorbornene) facilitates conduction of Li‐ions, resulting in improved performance relative to their poly(norbornene) counterparts. Specifically, higher reversible capacities are achieved at high current densities and initial capacity is better retained during prolonged cycling tests. Unlike previous strategies to increase the ionic conductivity of polymer electrodes, our design involves minimal synthetic steps and only contributes to a small increase in additional redox‐inactive mass, offering a versatile platform for high‐performance organic electrode materials.image

NASICON-structured Na3Fe2PO4(SO4)2: a potential cathode material for rechargeable sodium-ion batteries.

The cost-effective and abundant availability of sodium offers an opportunity for rechargeable Na-ion batteries as an ideal replacement for rechargeable Li-ion batteries. However, the larger size and strong Na+-Na+ interaction create multidimensional phase instability and transformation problems, especially in layer-structured NaxMO2 (Mn, Co, Fe, and Ni) that inhibit the direct transformation of rechargeable Li-ion battery technology to Na-ion batteries. However, framework structures offer superior structural stability due to the interconnection of polyanions or polyhedra forming cationic octahedra. Sodium superionic conductor (NASICON)-type structures are well known for their superior Na+ ion transport and are identified as intercalative hosts as electrodes for rechargeable Na-ion batteries. Here, we report the synthesis of Na3Fe2PO4(SO4)2 in a NASICON framework structure and its investigation as a cathode in a Na/Na3Fe2PO4(SO4)2 cell working on the Fe3+/Fe2+ redox couple. The cell provides a single-phase reaction having a capacity approaching 70 mA h g-1 at 0.1 C after 50 cycles in the voltage range of 2 to 4.2 V, with a columbic efficiency approaching 100%. The large availability of Na and Fe with the stable redox and charge/discharge performance of NASICON-type Na3Fe2PO4(SO4)2 make it a possible cathode candidate for next-generation rechargeable sodium-ion batteries.

Electroactive organics as promising anode materials for rechargeable lithium ion and sodium ion batteries

Electroactive organics have attracted significant attention as electrode materials for next-generation rechargeable batteries because of their structural diversity, molecular adjustability, abundance, flexibility, environmental friendliness and low cost. To date, a large number of organic materials have been applied in a variety of energy storage devices. However, the inherent problems of organic materials, such as their dissolution in electrolytes and low electronic conductivity, have restricted the development of organic electrodes. In order to solve these problems, many groups have carried out research and remarkable progress has been made. Nevertheless, most reviews of organic electrodes have focused on the positive electrode rather than the negative electrode. This review first provides an overview of the recent work on organic anodes for Li- and Na-ion batteries. Six categories of organic anodes are summarized and discussed. Many of the key factors that influence the electrochemical performance of organic anodes are highlighted and their prospects and remaining challenges are evaluated.

Criteria for evaluating lithium-air batteries in academia to correctly predict their practical performance in industry.

Although the market share for Li-ion batteries (LiBs) has continuously expanded, the limited theoretical energy density of conventional LiBs will no longer meet the advanced energy storage requirements. Lithium-air batteries (LABs) are potential candidates for next-generation rechargeable batteries because of their extremely high theoretical energy density. However, the reported values for the actual energy density of LABs are much lower than those for LiBs, mainly due to the excess amount of electrolyte in the cell. In the present review article, the practical energy density is estimated for the representative LABs reported in academia, and the critical factors for improving the energy density of LABs are summarized. The criteria for evaluating LABs in laboratory-based experiments are also proposed for accurately predicting the performance of practical cells in industry.

Uniform Li deposition assisted by dual carbon-confined CoO-NiO nanoparticles for dendrite-free Li metal anode

Li metal has been considered as one of the most promising anodes for next-generation rechargeable batteries. However, the growth of Li dendrites and the huge volume change limit its practical application. Herein, we have developed a CoO-NiO nanoparticles embedded in carbon polyhedral matrix (CPM) and reduced graphene oxide (rGO) sheets electrode with lithiophilic properties for a Li metal anode via a simple hydrothermal method followed by freeze-drying process and subsequent thermal annealing. The homogeneously distributed CoO-NiO nanoparticles serve as nucleation sites to effectively reduce the overpotential for Li nucleation. Moreover, CPM and rGO sheets lead to the double carbon-confined hierarchical composites with strong coupling effect, providing sufficient void space to withstand the volume expansion during Li deposition. As a result, the as-obtained composite delivers enhanced Columbic efficiency (~98.7% after 300 cycles) along with negligible nucleation overpotential. The symmetric cell can operate stably over 800 h at 1 mA cm−2 and even 120 h under 3 mA cm−2 with a fixed capacity of 1 mAh cm−2. Moreover, remarkable rate capability and long-term cycling stability (92.6% capacity retention after 300 cycles at 1 C) are obtained in full cells paired with a LiFePO4 cathode.

A Perspective on Li/S Battery Design: Modeling and Development Approaches

Lithium/sulfur (Li/S) cells that offer an ultrahigh theoretical specific energy of 2600 Wh/kg are considered one of the most promising next-generation rechargeable battery systems for the electrification of transportation. However, the commercialization of Li/S cells remains challenging, despite the recent advancements in materials development for sulfur electrodes and electrolytes, due to several critical issues such as the insufficient obtainable specific energy and relatively poor cyclability. This review aims to introduce electrode manufacturing and modeling methodologies and the current issues to be overcome. The obtainable specific energy values of Li/S pouch cells are calculated with respect to various parameters (e.g., sulfur mass loading, sulfur content, sulfur utilization, electrolyte-volume-to-sulfur-weight ratio, and electrode porosity) to demonstrate the design requirements for achieving a high specific energy of >300 Wh/kg. Finally, the prospects for rational modeling and manufacturing strategies are discussed, to establish a new design standard for Li/S batteries.

Single-atom catalysts for next-generation rechargeable batteries and fuel cells

The worldwide emission of greenhouse gasses combined with the lessening of crude oils is passionate about the research on sustainable energy conversion and storage devices. Further, the fast evolution of flexible and wearable opto-electronic systems, superior reliability, and ultra-long cycling lives of energy storage devices are of great importance. The poor kinetics of small reactions involved in next-generation energy devices are the main obstacles. The required electrode materials for these devices are emerging tasks for the betterment of these devices. Currently, single-atom catalysts (SACs) have gained pronounced interest as emerging and potential applicants as electrode materials for fruitful results. Herein, we have discussed the recent design principles for the fabrication of SACs for rechargeable batteries (Metal-air battery (Metal = Zn, Al, Li), Metal-sulfur battery, (Metal = Na, Li) and Metal-CO2 battery (Metal = Zn, Li)) and fuel cells. Then, we have summarized the recent advances in assembling and performance of these batteries using SACs as electrode materials. Finally, we have elucidated the role of SACs to resolve the bottle-neck problems of these next-generation energy storage systems. Following the discussion on short-comings and comprehensive future perspectives.

Poly(dopamine) surface‐modified polyethylene separator with electrolyte‐philic characteristics for enhancing the performance of sodium‐ion batteries

Sodium-ion batteries (NIBs) are promising candidates for next-generation rechargeable batteries with high energy density. Na ion with global abundance exhibits similar chemical characteristics to Li ion for rechargeable batteries. However, the polyethylene (PE) membrane, a conventional safety separator used for lithium-ion batteries, is inappropriate for NIBs due to its hydrophobic properties in NIBs liquid electrolytes and extremely poor ionic conductivity. Therefore, modifications to the PE separator are required to induce better electrochemical performance NIBs. Herein, we introduce a poly(dopamine)-modified PE separator by a simple dip-coating method, whereby the incorporation of the dopamine layer renders the membrane more hydrophilic in the liquid electrolyte of the NIBs. The PDA-PE separator exhibits high ionic conductivity and a long cycle life, and is stable with different current rates for Na||Na symmetric cells. Also, Na half-cell systems, consisting of hard carbon and Na metal electrodes, demonstrate considerably improved cyclability and high reversible discharge/charge with cells using PDA-treated PE separators.

A self-adapting artificial SEI layer enables superdense lithium deposition for high performance lithium anode

Metallic lithium (Li) is known to consider a critical role in next-generation rechargeable batteries. However, the uncontrolled growth of Li dendrites result in low Coulombic efficiency and safety issues in applications of Li metal batteries. High capacity and stable dense deposits of lithium metal are of great significant for high energy density battery. Herein, we propose a suitable degree of substitution for Carboxymethylcellulose Lithium (CMC-Li) as an artificial SEI layer, which has a high ionic transference number (0.66), high Young's modulus (24.6 GPa) and good lithiophilicity, then it can adapt to the volume changes of the lithium anode, enable superdense lithium deposits on Cu collector. The metallic lithium anode with CMC-Li films (CMC-Li@Li) delivers excellent cycling performance in the symmetrical cell at a large current density of 10 mA cm−2 and an areal capacity of 10 mAh cm−2 for almost 300 h. Moreover, the CMC-Li@Li||NCM613 full cell (N/P=2) delivers an initial specific capacity of 165 mAh g−1 with a high retention of 80% after 200 cycles.

A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

AbstractThe growing demand for sustainable energy storage devices requires rechargeable lithium‐ion batteries (LIBs) with higher specific capacity and stricter safety standards. Ni‐rich layered transition metal oxides outperform other cathode materials and have attracted much attention in both academia and industry. Lithium‐ion batteries composed of Ni‐rich layered cathodes and graphite anodes (or Li‐metal anodes) are suitable to meet the energy requirements of the next generation of rechargeable batteries. However, the instability of Ni‐rich cathodes poses serious challenges to large‐scale commercialization. This paper reviews various degradation processes occurring at the cathode, anode, and electrolyte in Ni‐rich cathode‐based LIBs. It highlights the recent achievements in developing new stabilization strategies for the various battery components in future Ni‐rich cathode‐based LIBs.

Eliminating anion depletion region and promoting Li+ solvation via anionphilic metal organic framework for dendrite-free lithium deposition

Lithium metal batteries (LMBs) have great potential for next-generation rechargeable batteries due to the high theoretical capacity and ideal compatibility coupled with diverse cathode materials. However, the random Li deposition associated with the large local space charge caused by the anion depletion near the surface of anode, as well as the insufficient reduction of Li+ related to the suppressed Li+ solvation process induced by the electrostatic force between anion and cation hinder the development of high-energy-density LMBs. Herein, as evidenced theoretically and experimentally, we simultaneously eliminate the anion depletion region and promote the lithium salt dissociation by employing ZIF-67 with unsaturated metal sites as anionphilic additive to regulate anion distribution and weaken its bond with Li+. As a result, the short-circuit hazard is remitted in symmetrical cell with modified electrolyte at 3 mA cm−2 under capacity of 3 mAh cm−2 for more than 2000 h. As employed for the lithium-sulfur battery with high sulfur loading of 4.5 mg cm−2, the modulated electrolyte enables the battery delivering an initial capacity of 713 mAh g−1 with decay rate of 0.05% per cycle over 100 cycles at 3 mA cm−2. This work demonstrates an efficient and scalable strategy for constructing dendrite-free LMBs via eliminating the anion depletion region and facilitating the Li+ solvation process.

Design of Quasi-MOF Nanospheres as a Dynamic Electrocatalyst toward Accelerated Sulfur Reduction Reaction for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered as one of the most promising next-generation rechargeable batteries owing to their high energy density and cost-effectiveness. However, the sluggish kinetics of the sulfur reduction reaction process, which is so far insufficiently explored, still impedes its practical application.Metal-organic frameworks (MOFs) are widely investigated asa sulfur immobilizer, but the interactions and catalytic activity of lithium polysulfides (LiPs) on metal nodes are weak due to the presence of organic ligands. Herein, a strategy to design quasi-MOF nanospheres, which contain a transition-state structure between the MOF and the metal oxide via controlled ligand exchange strategy, to serve as sulfur electrocatalyst, is presented. The quasi-MOF not only inherits the porous structure of the MOF, but also exposes abundant metal nodes to act as active sites, rendering strong LiPs absorbability. The reversible deligandation/ligandation of the quasi-MOF and its impact on the durability of the catalyst over the course of the electrochemical process is acknowledged, which confers a remarkable catalytic activity. Attributed to these structural advantages, the quasi-MOF delivers a decent discharge capacity and low capacity-fading rate over long-term cycling. This work not only offers insight into the rational design of quasi-MOF-based composites but also provides guidance for application in Li-S batteries.

Excess lithium enhances battery performance

Materials containing excess lithium exhibit higher energy density than conventional battery materials but still require more fundamental research before they can build the next generation of rechargeable batteries.

Crystallization behaviors in superionic conductor Na3PS4

All-solid-state batteries using sodium are promising candidates for next-generation rechargeable batteries due to the limited lithium resources. A practical sodium battery requires an electrolyte with high conductivity. Cubic Na$_3$PS$_4$ exhibiting high conductivity of over 10$^{-4}$ S cm$^{-1}$ is obtained by crystallizing amorphous Na$_3$PS$_4$ synthesized by ball milling. Amorphous Na$_3$PS$_4$ crystallizes in a cubic structure and then is transformed into a tetragonal phase upon heating. In this study, in situ observation by transmission electron microscopy demonstrates that the crystallite size drastically increases during the transition from the cubic phase to the tetragonal phase. Moreover, an electron diffraction analysis reveals that amorphous domains and nano-sized crystallites coexist in the cubic Na$_3$PS$_4$ specimen, while the tetragonal phase contains micro-sized crystallites. The nano-sized crystallites and the composite formed by crystallites and amorphous domains are most likely responsible for the increase in conductivity in the cubic Na$_3$PS$_4$ specimens.

Polypeptoid Material as an Anchoring Material for Li–S Batteries

Nowadays, lithium–sulfur (Li–S) batteries have attracted considerable attention as a potential candidate for next-generation rechargeable batteries due to their high theoretical specific energy and environmental friendliness. One of the main problems with Li–S batteries is that the lithium polysulfides (LiPSs) easily decompose in the electrolyte which is known as the shuttle effect. Recently, the polypeptoid nanosheet crystal structure has been experimentally synthesized which is very useful for tremendous advances in soft material imaging as well as enabling to design biomimetic nanomaterials. Due to the very interesting properties of the polypeptoid material, we have investigated the electronic structure and charge-transfer mechanism for the lithium–sulfur batteries for the cathode material. The calculated adsorption energies of LiPSs on the surface of the polypeptoid material are in the range of −4.41 to −4.64 and −0.91 eV for the sulfur clusters. Also, the adsorption energies between the interaction of LiPSs and electrolytes (DME and DOL) are 0.75–0.89 eV. It means that the polypeptoid material could suppress the shuttle effect of LiPSs and significantly enhance the cycling performance of Li–S batteries. From these investigated results, the polypeptoid material will be a promising anchoring material for Li–S batteries.

Understanding the Failure Mechanism of Rechargeable Aluminum Batteries: Metal Anode Perspective Through X‐Ray Tomography

Rechargeable aluminum batteries (AlBs), which represent cost‐effective energy‐storage devices due to the abundance of natural aluminum resources, have emerged as promising candidates for the next generation of rechargeable batteries. Although the electrochemical deposition of aluminum in ionic liquids (ILs) is well investigated for aluminum refining, the reversible electrochemical deposition/dissolution behavior of aluminum ions is not trivial. More specifically, the dendrite growth issue, which is common in Li metal anodes, is scarcer or vague. Herein, the electrochemical stability of the aluminum metal anode in IL electrolytes is investigated and the failure mechanism is discussed. It is confirmed that the inorganic anion of ILs mainly affects the electrochemical stability, whereas the organic cation influences the aluminum metal degradation. X‐ray computed tomography results further identify deterioration of the surface morphology of the aluminum metal. The formation of “dead aluminum” is further confirmed, which indeed causes cell failure with repeated cycles. Finally, using the predeposited aluminum graphene paper as an alternative anode candidate for AlBs is further demonstrated.

Atomically Thin Materials for Next-Generation Rechargeable Batteries.

Atomically thin materials (ATMs) with thicknesses in the atomic scale (typically <5 nm) offer inherent advantages of large specific surface areas, proper crystal lattice distortion, abundant surface dangling bonds, and strong in-plane chemical bonds, making them ideal 2D platforms to construct high-performance electrode materials for rechargeable metal-ion batteries, metal-sulfur batteries, and metal-air batteries. This work reviews the synthesis and electronic property tuning of state-of-the-art ATMs, including graphene and graphene derivatives (GE/GO/rGO), graphitic carbon nitride (g-C3N4), phosphorene, covalent organic frameworks (COFs), layered transition metal dichalcogenides (TMDs), transition metal carbides, carbonitrides, and nitrides (MXenes), transition metal oxides (TMOs), and metal-organic frameworks (MOFs) for constructing next-generation high-energy-density and high-power-density rechargeable batteries to meet the needs of the rapid developments in portable electronics, electric vehicles, and smart electricity grids. We also present our viewpoints on future challenges and opportunities of constructing efficient ATMs for next-generation rechargeable batteries.