Rechargeable Battery Systems Research Articles

Bismuth Enables the Formation of Disordered Birnessite in Rechargeable Alkaline Batteries

Recent advances in rechargeable Zn/MnO2 alkaline batteries have shown promise for scalable energy storage systems which provide a safe, low-cost alternative with a demonstrated lifetime over thousands of cycles. This cathode technology is based on a 2-electron Mn redox process where a layered birnessite-type phase has been shown to form after the first cycle with excellent reversibility between the discharge product, Mn(OH)2. Herein, we investigate the reversible reaction between birnessite and Mn(OH)2 with and without a Bi2O3 additive using multimodal structural characterization techniques during active battery cycling. Diffraction results provide evidence of Bi3+ residing in the interlayer of birnessite which prevents irreversible Mn3O4 formation by limiting Mn3+ diffusion within the crystal lattice. Also, upon charge no MnOOH intermediate phases are observed. Instead, X-ray absorption and Raman spectroscopy indicate a disordered, non-crystalline birnessite-type phase consisting of mostly neutral H2O within the interlayer. Birnessite phases will reform without Bi2O3 present, but Mn3O4 formation severely polarizes the potential they are formed at, leading to capacity fade. Also, we discuss the reversible Bi2O3 conversion to Bi0 and its contribution to the observed capacity. We expect the results will provide crucial insight into the development of aqueous, rechargeable battery systems utilizing MnO2.

Synthesis and Applications of Aurin Tricarboxylic Acid-Copper Metal Organic Framework for Rechargeable Lithium-Ion Batteries

Organic electrode materials for lithium-ion batteries are essential tools for energy storage systems starting from portable electronics to electric vehicles. Many attempts have been made to improve the electrochemical behavior of organic electrode materials for lithium-ion batteries. Herein we have proposed a new electrode material called Aurin tricarboxylic acid synthesized via the condensation of aldehyde and acid in the presence of sodium nitrite which is further converted into the metal-organic framework using copper salt to increase its conductivity and used as an anode material for both aqueous and non-aqueous rechargeable lithium-ion batteries. The electrochemical performance of modified Aurin Tricarboxylic acid copper metal-organic framework (ATC-MOF) was studied using cyclic voltammetry, galvanostatic cycling with potential limitation and Potentio electrochemical impedance spectroscopy techniques and the structures were confirmed using 1H-NMR, FT-IR spectroscopy, and Powder XRD techniques. It exhibits excellent cyclability and a good discharge capacity of about 438.09 mA h g−1 in a non-aqueous electrolyte and 169.69 mAh g−1 in an aqueous electrolytic system. The electrochemical activity of the ATC-MOF shows that it can be used as electrode material in aqueous and non-aqueous rechargeable lithium-ion battery systems.

3D printing of structured electrodes for rechargeable batteries

An overview of 3D printed rechargeable batteries is provided, comparing electrodes/electrolytes with different structures and their applications in rechargeable battery systems.

Supercharged!

Supercharged!

Initial investigation and evaluation of potassium metal as an anode for rechargeable potassium batteries

This work highlights recent progress on K metal as an anode and provides a valuable outlook on the scientific and practical issues concerning the development of rechargeable potassium-based battery systems.

Design of Rechargeable Battery System for Mandibular Distraction Osteogenesis Device

Design of Rechargeable Battery System for Mandibular Distraction Osteogenesis Device

Materials electrochemistry for high energy density power batteries

On June 30th of 2019, China Association for Science and Technology announced the list of twenty questions that are considered either of guiding importance for frontiers of sciences or playing crucial roles in technological and industrial innovation. Among which the question 4 is “materials electrochemistry for high energy density power batteries”. This article is an interpretation of this question, including a basic overview of the current technology, industry and market of lithium ion battery for powering electric vehicles, the trends of future development, and where the scientific problems are. Along with the rapid economic development in the last a few decades, the vehicle market in China has grown dramatically in recent years. The total number of vehicles in China is already exceeding 0.2 billion, which makes twenty percent of the total number in the world. And this number keeps increasing at a fast pace since the number of vehicle per capital in China is still much lower than those of developed countries (the average number of vehicles per thousand person at year 2016: China-140, USA-797, Japan-591, Korea-376). The huge number of vehicles in China consume a large amount of fuel oil (about 50% of the total fuel oil consumption of China every year are attributed to vehicles), which is prepared from petroleum, a scarce resource in China. Fossil fuel consumption also causes severe air pollution that threatens people’s health and results in global environmental concerns considering the consequences arising from the excessive emission of Greenhouse Gases such as CO2. Development of electric vehicles (EVs) to replace fossil fuel consuming vehicles is a promising solution to tackle the fossil energy exhaustion, global warming, and environment pollution problems, realizing a low-carbon society, and is also an opportunity for China to develop the automobile industry. However, the energy density of the current power batteries used in the EVs is still much lower than that of the fossil energy, which causes the so-called “range anxiety” in EV drivers, hindering the mass-market penetration of EVs. Therefore, overcoming the “range anxiety” by developing higher energy density power batteries is a critical technological challenge for innovative revolution of the vehicle market. Usually, driving ranges of at least 500 km are required for EVs to achieve wide customer acceptance. However, the state-of-the-art lithium-ion battery, which has the highest energy density among all mass-produced rechargeable battery systems, barely meets this requirement when battery safety and cycle lifetime are also concerned. Since the energy density of rechargeable batteries is in principle determined by the active anode and cathode materials, the development of new materials chemistry and electrochemistry is the central scientific task for the popularization of EVs. A survey of currently or potentially available active materials is thus helpful in making a technologically sound forecast of battery energy density as well as in setting up EV development roadmap. In this paper, we briefly go through the materials electrochemistry for current and future active materials for lithium ion batteries and lithium metal batteries, thus including both intercalation and conversion reaction mechanisms, and assess the potential of these active materials in the coming decade to achieve energy density as high as 300 Wh/kg or even higher. The scientific questions and technological challenges that need to be addressed to achieve the goal are analyzed and emphasized. We hope this article will help the readers to unravel the complex power battery market, and potentially inspire researchers in the field to solve the “materials electrochemistry for high energy density power batteries” problem.

Rechargeable Intermetallic Calcium-Lithium-O2 Batteries.

The growing demand for rechargeable batteries with high energy density has triggered research on batteries based on polyvalent cations such as Ca2+ , Mg2+ , Al3+ , and Y3+ . Ca is, in particular, a promising anode material as an alternative to Li because of its mechanical strength (ρ=1.55 g cm-3 ), safety in terms of thermal runaway (m.p.=839 °C), earth-abundance (world production of 150 million tons of gypsum in 2012), high specific charge capacity (1.340 mAh g-1 or 2.077 mAh cm-3 ), and standard reduction potential (-2.87 V vs. normal hydrogen electrode, NHE) comparable to that of Li. As with Mg, the practical application of Ca in rechargeable batteries with organic liquid electrolytes has been hindered by the passivation layer resulting from undesirable reactions between metallic Ca and electrolytes, which precludes the possibility of reversible plating of any metal cations on Ca electrodes. Here, a battery system based on intermetallic CaLi2 anodes was developed. Li was used as a host for Ca through the formation of an intermetallic compound, which simultaneously enabled 1) the assembly of a rechargeable battery system with Ca anodes and liquid organic electrolytes and 2) coupling these with an earth-abundant, high-energy-density air cathode without special passivation agents. This strategy is simple and broadly applicable to the other polyvalent cations listed above, opening a new avenue to further engineer the electrode materials required for practical, efficient electrochemical energy-storage systems.

Strategies towards Low-Cost Dual-Ion Batteries with High Performance.

Rocking-chair based lithium-ion batteries (LIBs) have extensively applied to consumer electronics and electric vehicles (EVs) for solving the present worldwide issues of fossil fuel exhaustion and environmental pollution. However, due to the growing unprecedented demand of LIBs for commercialization in EVs and grid-scale energy storage stations, and a shortage of lithium and cobalt, the increasing cost gives impetus to exploit low-cost rechargeable battery systems. Dual-ion batteries (DIBs), in which both cations and anions are involved in the electrochemical redox reaction, are one of the most promising candidates to meet the low-cost requirements of commercial applications, because of their high working voltage, excellent safety, and environmental friendliness compared to conventional rocking-chair based LIBs. However, DIB technologies are only at the stage of fundamental research and considerable effort is required to improve the energy density and cycle life further. We review the development history and current situation, and discuss the reaction kinetics involved in DIBs, including various anionic intercalation mechanism of cathodes, and the reactions at the anodes including intercalation and alloying to explore promising strategies towards low-cost DIBs with high performance.

Effect of drying temperature on polyaniline electrode for polyaniline|Zn battery performance

ABSTRACT . Here, we report the effect of various drying temperature of Polyaniline (PAni) on battery PAni|Zn performance. PAni was synthesized using the electrodeposition method on the surface of the graphite sheets (GS), at 0.7 V relative to the saturated Ag/AgCl. PAni is dried with various temperature, 25, 80, 120, and 180 o C, respectively. PAni was characterized by Raman spectroscopy; then the performance Pani battery was studied in a rechargeable battery system. The measurement results found the PAni|Zn battery with 25 o C temperature drying of PAni was a good performance which the capacity density stable at 175–105 mAh g -1 until 100 cycles. Raman study showed that high-temperature drying resulted in a cleavage peak at 1188 cm -1 and increased peak intensity at 1495 cm -1 . This vibrational mode appears as a stretching ν(C-C) on the semi quinonoid ring and ν(C=N) on the quinoid ring. This phenomenon indicated the changing structure of PAni to be Emeraldine base form. KEY WORDS : Aniline, Annealing, Polyaniline, Rechargeable battery, Temperature effect Bull. Chem. Soc. Ethiop. 2019 , 33(3), 551-559. DOI: https://dx.doi.org/10.4314/bcse.v33i3.15

Manganese carbonate as active material in potassium carbonate electrolyte

In this work, we explore the possibility of using MnCO3 as active material for alkaline rechargeable batteries. K2CO3 solution is chosen as electrolyte because the solubility of MnCO3 in K2CO3 electrolyte keeps lower than that in KOH electrolyte of the same pH values, which may promote the cyclability of MnCO3. XRD and XPS measurements reveal a two-electron transfer reaction during cycling, corresponding to the conversion of MnCO3/MnO2. Further investigations demonstrate the MnCO3 electrode can be cycled 50 cycles without obvious capacity decay and the coulombic efficiency keeps over 95.0% after the 8th cycle. The present study provides a new perspective in searching new electrode materials and electrolyte systems for alkaline rechargeable batteries.

Rechargeable-battery chemistry based on lithium oxide growth through nitrate anion redox.

Next-generation lithium-battery cathodes often involve the growth of lithium-rich phases, which enable specific capacities that are 2-3 times higher than insertion cathode materials, such as lithium cobalt oxide. Here, we investigated battery chemistry previously deemed irreversible in which lithium oxide, a lithium-rich phase, grows through the reduction of the nitrate anion in a lithium nitrate-based molten salt at 150 °C. Using a suite of independent characterization techniques, we demonstrated that a Ni nanoparticle catalyst enables the reversible growth and dissolution of micrometre-sized lithium oxide crystals through the effective catalysis of nitrate reduction and nitrite oxidation, which results in high cathode areal capacities (~12 mAh cm-2). These results enable a rechargeable battery system that has a full-cell theoretical specific energy of 1,579 Wh kg-1, in which a molten nitrate salt serves as both an active material and the electrolyte.

Recent nanosheet-based materials for monovalent and multivalent ions storage

Owing to the unique advantages of short solid-state diffusion length for metal ions, outstanding ability to alleviate the huge volume expansion of the electrode during repeated charge/discharge process, considerable large amount of channels for electrolyte access leading promoting fast ion diffusion between electrode, and numerous exposed active sites, nanosheet structures are regarded as the ideal electrode structures for achieving high capacity and ultrafast charge/discharge of energy storage. Herein, this review provides a comprehensive introduction of recent nanosheet-based electrode materials for high performance batteries, like monovalent ion (lithium and sodium) batteries and multivalent ion (magnesium, zinc and aluminum) batteries. Facile and simple strategies of synthesizing electrodes and different mechanisms of energy storage are presented. Furthermore, the challenges and development directions of nanosheet-based materials and rechargeable battery systems are discussed.

Controlling Li Ion Flux through Materials Innovation for Dendrite‐Free Lithium Metal Anodes

AbstractLithium (Li) metal with high theoretical capacity and the lowest electrochemical potential has been proposed as the ideal anode for high‐energy‐density rechargeable battery systems. However, the practical commercialization of Li metal anodes is precluded by a short lifespan and safety problems caused by their intrinsically high reductivity, infinite volume change, and uncontrollable dendrite growth during deposition and dissolution processes. Plenty of strategies have been introduced to solve the above‐mentioned problems. Among these, controlling Li+ flux plays a vital role to directly influence the plating and stripping process. In this work, the fundamental effect of Li+ flux distribution on Li nucleation and early dendrite growth is discussed. Then, recent strategies of controlling Li+ flux to suppress dendrite formation and growth through materials design are summarized, including homogenizing Li+ flux, localizing Li+ flux, and guiding gradient Li+ distribution. Finally, underexplored materials are proposed and explored to control Li+ flux and further directions for dendrite‐free Li anodes. It is expected that this progress report will help to deepen the understanding of Li+ flow tuning and morphology control of Li anodes and eventually facilitate the practical application of Li metal batteries.

Thermoplastic Polyurethane Elastomer-Based Gel Polymer Electrolytes for Sodium-Metal Cells with Enhanced Cycling Performance.

Sodium batteries have been recognized as a promising alternative to lithium-ion batteries. However, the liquid electrolyte used in these batteries has inherent safety problems. Polymer electrolytes have been considered as safer and more reliable electrolyte systems for rechargeable batteries. Herein, a thermoplastic polyurethane elastomer-based gel polymer electrolyte with high ionic conductivity and high elasticity was reported. It had an ambient-temperature ionic conductivity of 1.5 mS cm-1 and high stretchability, capable of withstanding 610 % strain. Coordination between Na+ ions and polymer chains increased the degree of salt dissociation in the gel polymer electrolyte compared with the liquid electrolyte. An Na/Na3 V2 (PO4 )3 cell assembled with gel polymer electrolyte exhibited good cycling performance in terms of discharge capacity, cycling stability, and rate capability, which was owing to the effective trapping ability of organic solvents in the polymer matrix and uniform flux of sodium ions through the gel polymer electrolyte.

Carbon Inverse Opals As a Sulfur Host for Advanced Lithium–Sulfur Batteries

Lithium Sulfur (Li–S) batteries are one of the most promising “beyond-lithium-ion” rechargeable battery systems in terms of both cost and specific energy density. (1, 2) Sulfur is one of the most abundant elements in the Earth’s crust and offers a high theoretical specific charge of 1672 mAh/g. (3) Furthermore, Li–S batteries can deliver a practical specific energy density of 400-600 Wh/kg, which is more than double the values offered by state-of-the-art lithium-ion batteries. (4, 5) However, issues related to the inherent insulating nature of S and the polysulfide shuttle continue to hinder the widespread commercialization of Li–S batteries. Consequently, there has been a significant research effort to identify S hosts that can assist in mitigating these limitations. Porous carbon materials have attracted a great deal of attention due to their excellent conductivity, high surface area and light weight. (6) Activated carbons and hollow carbon spheres (HCSs) have been shown to significantly improve the electrochemical performance of Li–S batteries in terms of specific capacity and its retention. (7-10) Inverse opal (IO) structured electrodes offer many potential benefits as a S host material. The spherical voids of an inverse opal can be filled with S and ensure good access of the electrolyte to the electrode surface. The carbon IOs may act as a highly ordered, three-dimensional, conductive scaffold to reduce lithium polysulfide dissolution into the electrolyte during cycling, thus reducing the effects of the detrimental polysulfide shuttle. Additionally, during discharge S is reduced to form Li2S and with prolonged cycling this process leads to structural instability of electrodes due to the large volume expansion (~80%) caused by S conversion into Li2S. The spherical pores of a carbon IO scaffold may constrain the volume expansion due to the formation of Li2S and therefore increase capacity retention. IOs and HCSs are typically synthesised using silica nanospheres, which require treatment in hydrofluoric acid or long-term exposure to highly basic solutions to etch away the hard template. (11, 12) In this work we detail the facile synthesis of carbon IO structured samples using polystyrene nanospheres, which are easily removed via thermal treatment, and their application as a S host material for Li–S batteries. We present a structural characterization of our carbon IO samples via analysis of Raman spectra, Fourier-transform infrared spectra and X-ray diffraction patterns. The electrochemical performance of the carbon IO S-hosts is evaluated via cyclic voltammetry, rate capability testing and long-term galvanostatic cycling tests. We demonstrate that our S infilled carbon IO cathodes are capable of delivering high specific charges with stable capacity retention, achieving a reversible capacity of ~ 750 mAh/g after the 100 cycles at a C/5 rate. The morphology of the carbon IOs after cycling will also be shown via ex-situ scanning electron microscopy. We demonstrate that by preparing a highly ordered, conductive, three dimensionally interconnected network in the form of a carbon IO and then infilling this porous scaffold with S, we can achieve specific charge values which are greater than standard S/C composite slurry electrodes.

Understanding the Effect of Polymer Surface Layers on Magnesium Insertion in PEDOT/MnO2 Coaxial Nanowires

Rechargeable magnesium batteries are a possible alternative technology to lithium-ion batteries. However, there are challenges associated with all parts of magnesium battery systems – anode, cathode, and electrolyte. Regarding cathodes, the divalent Mg ion has slow insertion kinetics in many common metal oxide materials due to strong electrostatic interactions with the host ionic lattice. These materials are desirable due to their high voltage and thus the potential to contribute to a high energy density battery, therefore strategies to aid Mg2+ insertion in metal oxides are an important research focus. Two strategies to improve Mg2+ insertion include utilizing nanostructured cathode materials as well as introducing water, either in the electrolyte or crystal water within the metal oxide structure. Previous work demonstrated that manganese dioxide (MnO2) nanowires deposited via anodic electrodeposition effectively intercalated Mg ions when water was present in a ratio of 6:1 (H2O:Mg2+) in Mg(ClO4)2/propylene carbonate electrolyte (1). Without water in the electrolyte to solvate the Mg2+ and shield the charge, Mg2+ does not insert into the MnO2. Further, an investigation of the charge storage mechanism for this process determined that a conversion reaction on the MnO2 surface in addition to Mg insertion into the bulk both were dependent on the presence of water (2). Following this work, there were two additional characteristics of interest regarding MnO2 cathodes cycled in water-containing organic electrolyte: manganese dissolution and electronic conductivity. A previously published one-step co-electrodeposition process of MnO2 and poly(3,4-ethylenedioxythiophene)(PEDOT) provided a tunable structure to test both effects (3). With the PEDOT surface layer, there are two possible advantages: first is confining the MnO2 layer to minimize Mn dissolution, and second is addition of the more electronically conductive PEDOT layer for fast electron transport along the comparatively resistive MnO2 material. Here, coaxial PEDOT/MnO2 nanowires served as a test structure to investigate how a PEDOT surface layer affected Mg ion insertion into the MnO2 at the core and to develop additional understanding of the properties of MnO2 and how structural alterations could influence the electrochemical reactions. By altering the voltage of electrodeposition, the thickness of the PEDOT layer was varied. Cyclic voltammetry and galvanostatic charge/discharge tests were done to evaluate the Mg insertion capabilities, power performance, and cyclability of coaxial nanowires with PEDOT thicknesses ranging from 10-90 nm. Transmission electron microscopy and scanning electron microscopy were used to monitor structural properties and changes. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to monitor changes in manganese content. This work will address how PEDOT thickness influences the ability of Mg2+ to insert into MnO2, how it affects Mn dissolution, and how the increased electronic conductivity of PEDOT impacts performance when cycling at higher current densities. These results could help inform better design of future cathode materials for rechargeable Mg battery systems. 1. J. Song, M. Noked, E. Gillette, J. Duay, G. Rubloff and S. B. Lee, Physical Chemistry Chemical Physics, 17, 5256 (2015).2. E. Sahadeo, J. Song, K. Gaskell, N. Kim, G. Rubloff and S. B. Lee, Physical Chemistry Chemical Physics, 20, 2517 (2018).3. R. Liu and S. B. Lee, Journal of the American Chemical Society, 130, 2942 (2008).

Mixtures of Ionic Liquid and Organic Electrolyte with Improved Safety and Electrochemical Performance with Nanostructured Silicon-Anode for Li-Ion Batteries

The present rechargeable lithium-ion battery systems commonly use small amount of electrolytes based on suitable lithium salts (generally LiPF6) and organic solvents (generally alkylcarbonates, such as EC, DMC), which represent a major concern for device safety due to the flammable and volatile nature of these organic liquids. The use of these organic carbonates electrolytes allows the realization of high-performance batteries, but due to its flammability, their use also poses serious safety risks and strongly reduces the battery operative temperature range. Therefore, alternative electrolytes have been proposed and tested in the last decade [1]. Ionic liquids doped with a lithium salt are alternative electrolytes for lithium-ion batteries that offer some advantages compared to organic carbonates based liquid electrolytes. Ionic liquids display a low vapor pressure which leads to nonflammability. The main drawback of ionic liquid-based electrolytes is the low lithium-ion conductivity due to relatively high viscosity of ionic liquids. A lot of research has been devoted to developing ionic liquids with low viscosity. However, so far, these ionic liquids could be obtained only at the expense of lower thermal and/or electrochemical stability. In recent years, mixtures of organic carbonates-based electrolytes and ionic liquids have been proposed as a solution to overcome the lithium-ion transport limitations of ionic liquid-based electrolytes while improving safety due to a lower flammability than that of organic carbonates electrolytes [1, 2]. Herein, we report the results of physical-chemical and electrochemical investigations performed on mixed electrolytes based on an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI), and organic electrolytes (LiTFSI in EC/DMC) with nanostructured silicon-anode for lithium-ion batteries. The ionic conductivity, lithium-ion transference number, viscosity and electrochemical stability windows of all different ionic liquid content mixtures were investigated and compared with carbonates-based electrolyte. The specific capacity and cycling stability of the nanostructured silicon-anode were investigated at different C-rates at room temperature. A reversible capacity of 3480 mAh g-1 (of Si) at C/10 and 1600 mAh g-1 at 5C is obtained with cells having electrolyte mixture with a composition of 1:1. This study indicates that safety and electrochemical performance of the Si-anode for Li-ion battery can be improved by using mixed ionic liquid and carbonates-based electrolytes. [1] A. Guerfi, M. Dontigny, P. Charest, M. Petitclerc, M. Lagacé, A. Vijh, K. Zaghib, J. Power Sources 195 (2010) 845-852. [2] R.-S. Kühnel and A. Balducci, J. Phys. Chem. C 118 (2014) 5742-5748.

Facet Engineering of Low-Cost Transitional Metal Oxides for Tunable ORR/OER Kinetics

To meet future needs for industries from personal devices to automobiles, energy storage devices are transitioning into the next-generation advanced battery systems beyond lithium ions with higher energy density. Among them, lithium-oxygen (Li-O2) battery stands out due to its highest theoretical energy density among all rechargeable ion battery systems. Yet, its application is severely disabled by the sluggish reaction kinetics during oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). To address this problem, various catalysts have been developed with the most promising materials being the noble metals (Pt, etc.) and transitional metal oxides (TMOs such as CoxOy, MnxOy, etc.). While the noble metal catalysts offer superior performance in terms of improving the reaction kinetics, the high cost and environmental sensitivity prevent the large-scale application. As an alternative, TMOs are attracting more and more interest because they exhibit satisfactory catalytic performance while their cost and cycling durability are much better than that of noble metals. While most studies have focused on the development of different TMO structures, phases and compositions, few studies have reported the advancement in the crystalline facet engineering, particularly for the low-cost TMOs such as manganese oxides, and its effect on ORR/OER kinetics. In this work, beta-(β-)MnO2 crystals with either octahedron or rod-like shapes were successfully synthesized separately using a simple hydrothermal method. Combining various electron microscopic methods, the octahedron’s surface is seen to mostly occupied by MnO2-{111} facets, while rod’s surface is occupied by MnO2-{100}. As the cathode for Li-air batteries, the β-MnO2 with {111} facets and {100} facets catalyzed the formation of Li2O2 into large toroids and thin film, respectively. For the first time, we revealed that the control of crystal facets can switch the Li2O2 formation mechanism from the surface mode to the solution mode even in the low donor number TEGDME electrolyte. To further understand the formation kinetics of Li2O2, we referred to operando liquid cell transmission electron microscopy, by which a LiO2 phase was identified to function as the intermediate discharge products which significantly affect the formation of Li2O2 as the final product. Following this finding, DFT results further showed that the different catalytic properties were due to the different adsorption free energies for the LiO2 intermediate on the {111} and {100} facets of MnO2. Our findings revealed that facet-engineering of the low-cost TMO catalysts would open a new way for the design of lithium-air batteries with high stabilities and long cycle life. Figure 1

Biological Nicotinamide Cofactor as a Redox‐Active Motif for Reversible Electrochemical Energy Storage

AbstractNicotinamide adenine dinucleotide (NAD+) is one of the most well‐known redox cofactors carrying electrons. Now, it is reported that the intrinsically charged NAD+ motif can serve as an active electrode in electrochemical lithium cells. By anchoring the NAD+ motif by the anion incorporation, redox activity of the NAD+ is successfully implemented in conventional batteries, exhibiting the average voltage of 2.3 V. The operating voltage and capacity are tunable by altering the anchoring anion species without modifying the redox center itself. This work not only demonstrates the redox capability of NAD+, but also suggests that anchoring the charged molecules with anion incorporation is a viable new approach to exploit various charged biological cofactors in rechargeable battery systems.