Na‐ion batteries (NIBs) are ideal candidates for solving the problem of large‐scale energy storage, due to the worldwide sodium resource, but the efforts in exploring and synthesizing low‐cost and ...eco‐friendly anode materials with convenient technologies and low‐cost raw materials are still insufficient. Herein, with the assistance of a simple calcination method and common raw materials, the environmentally friendly and nontoxic N‐doped C@Zn3B2O6 composite is directly synthesized and proved to be a potential anode material for NIBs. The composite demonstrates a high reversible charge capacity of 446.2 mAh g−1 and a safe and suitable average voltage of 0.69 V, together with application potential in full cells (discharge capacity of 98.4 mAh g−1 and long cycle performance of 300 cycles at 1000 mA g−1). In addition, the sodium‐ion storage mechanism of N‐doped C@Zn3B2O6 is subsequently studied through air‐insulated ex situ characterizations of X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Fourier‐transform infrared (FT‐IR) spectroscopy, and is found to be rather different from previous reports on borate anode materials for NIBs and lithium‐ion batteries. The reaction mechanism is deduced and proposed as: Zn3B2O6 + 6Na+ + 6e− ⇋ 3Zn + B2O3 ∙ 3Na2O, which indicates that the generated boracic phase is electrochemically active and participates in the later discharge/charge progress.
N‐doped C@Zn3B2O6 (NC@ZBO) composite is chemically synthesized in a green manner through a simple method, and shows considerable sodium‐ion storage ability, including high reversible charge capacity (446.2 mAh g−1) and suitable average voltage (0.69 V), together with application potential in full cells (300 cycles). The sodium‐ion storage mechanism of Zn3B2O6 is also found rather different from relevant experiments on borates and deduced to be Zn3B2O6 + 6Na+ + 6e− ⇋ 3Zn + B2O3 · 3Na2O.
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Li‐O2 batteries with ultrahigh theoretical energy densities usually suffer from low practical discharge capacities and inferior cycling stability owing to the cathode passivation caused by insulating ...discharge products and by‐products. Here, a trifunctional ether‐based redox mediator, 2,5‐di‐tert‐butyl‐1,4‐dimethoxybenzene (DBDMB), is introduced into the electrolyte to capture reactive O2− and alleviate the rigorous oxidative environment of Li‐O2 batteries. Thanks to the strong solvation effect of DBDMB towards Li+ and O2−, it not only reduces the formation of by‐products (a high Li2O2 yield of 96.6 %), but also promotes the solution growth of large‐sized Li2O2 particles, avoiding the passivation of cathode as well as enabling a large discharge capacity. Moreover, DBDMB makes the oxidization of Li2O2 and the decomposition of main by‐products (Li2CO3 and LiOH) proceed in a highly effective manner, prolonging the stability of Li‐O2 batteries (243 cycles at 1000 mAh g−1 and 1000 mA g−1).
A trifunctional ether‐based redox mediator, DBDMB, is introduced into the electrolyte to capture reactive discharge intermediates (O2−) with reduced formation of by‐products, regulate solution growth of Li2O2, and co‐oxidize Li2O2 and by‐products (Li2CO3 and LiOH). Li‐O2 batteries with large capacity and long cycling stability have been achieved.
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The limited triple‐phase boundaries (TPBs) in solid‐state cathodes (SSCs) and high resistance imposed by solid electrolytes (SEs) make the achievement of high‐performance all‐solid‐state ...lithium‐oxygen (ASS Li‐O2) batteries a challenge. Herein, an adjustable‐porosity plastic crystal electrolyte (PCE) has been fabricated by employing a thermally induced phase separation (TIPS) technique to overcome the above tricky issues. The SSC produced through the in‐situ introduction of the porous PCE on the surface of the active material, facilitates the simultaneous transfer of Li+/e−, as well as ensures fast flow of O2, forming continuous and abundant TPBs. The high Li+ conductivity, softness, and adhesion of the dense PCE significantly reduce the battery resistance to 115 Ω. As a result, the ASS Li‐O2 battery based on this adjustable‐porosity PCE exhibits superior performances with high specific capacity (5963 mAh g−1), good rate capability, and stable cycling life up to 130 cycles at 32 °C. This novel design and exciting results could open a new avenue for ASS Li‐O2 batteries.
Holey cathodes, Battman! An adjustable‐porosity plastic crystal electrolyte (PCE) has been fabricated to solve the problems of high resistance and limited triple‐phase boundaries in all‐solid‐state lithium‐oxygen (ASS Li‐O2) batteries. The ASS Li‐O2 battery with dense PCE and porous PCE‐based solid‐state cathode shows ultra‐low resistance (115 Ω), large capacity (5963 mAh g−1), good rate capability, and long cycle life (130 cycles) at 32 °C.
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With the rapid development of wearable and portable electronics, flexible and stretchable energy storage devices to power them are rapidly emerging. Among numerous flexible energy storage ...technologies, flexible batteries are considered as the most favorable candidate due to their high energy density and long cycle life. In particular, flexible 1D batteries with the unique advantages of miniaturization, adaptability, and weavability are expected to be a part of such applications. The development of 1D batteries, including lithium‐ion batteries, zinc‐ion batteries, zinc–air batteries, and lithium–air batteries, is comprehensively summarized, with particular emphasis on electrode preparation, battery design, and battery properties. In addition, the remaining challenges to the commercialization of current 1D batteries and prospective opportunities in the field are discussed.
The latest advances in flexible 1D batteries, including metal‐ion batteries and metal–air batteries, are summarized, with particular emphasis on electrode preparation, battery design, and electrochemical and mechanical properties. Additionally, future perspectives on and remaining challenges to the practical application of 1D batteries are also discussed to promote the commercialization of 1D batteries.
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Nitrogen‐doped carbon (NC) materials have been proposed as next‐generation oxygen reduction reaction (ORR) catalysts to significantly improve scalability and reduce costs, but these alternatives ...usually exhibit low activity and/or gradual deactivation during use. Here, we develop new 2D sandwich‐like zeolitic imidazolate framework (ZIF) derived graphene‐based nitrogen‐doped porous carbon sheets (GNPCSs) obtained by in situ growing ZIF on graphene oxide (GO). Compared to commercial Pt/C catalyst, the GNPCSs show comparable onset potential, higher current density, and especially an excellent tolerance to methanol and superior durability in the ORR. Those properties might be attributed to a synergistic effect between NC and graphene with regard to structure and composition. Furthermore, higher open‐circuit voltage and power density are obtained in direct methanol fuel cells.
Nitrogen‐doped: A new oxygen reduction reaction electrocatalyst was obtained from ZIF‐derived porous carbon and graphene. The catalyst exhibits high activity, superior tolerance to methanol, and good stability in comparison to commercial Pt/C catalyst.
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A novel in situ replication and polymerization strategy is developed for the synthesis of Fe‐N‐doped mesoporous carbon microspheres (Fe‐NMCSs). This material benefits from the synergy between the ...high catalytic activity of Fe‐N‐C and the fast mass transport of the mesoporous microsphere structure. Compared to commercial Pt/C catalysts, the Fe‐NMCSs show a much better electrocatalytic performance in terms of higher catalytic activity, selectivity, and durability for the oxygen reduction reaction.
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Conspectus It is a permanent issue for modern society to develop high-energy-density, low-cost, and safe batteries to promote technological innovation and revolutionize the human lifestyle. However, ...the current popular Li-ion batteries are approaching their ceiling in energy density, and thus other battery systems with more power need to be proposed and studied to guide this revolution. Lithium–air batteries are among the candidates for next-generation batteries because of their high energy density (3500 Wh/kg). The past 20 years have witnessed rapid developments of lithium–air batteries in electrochemistry and material engineering with scientists’ collaboration from all over the world. Despite these advances, the investigation on Li–air batteries is still in its infancy, and many bottleneck problems, including fundamental and application difficulties, are waiting to be resolved. For the electrolyte, it is prone to be attacked by intermediates (LiO2, O2 –, 1O2, O2 2–) and decomposed at high voltage, accompanying side reactions that will induce cathode passivation. For the lithium anode, it can be corroded severely by H2O and the side products, thus protection methods are urgently needed. As an integrated system, the realization of high-performance Li–air batteries requires the three components to be optimized simultaneously. In this Account, we are going to summarize our progress for optimizing Li–air batteries in the past decade, including air-electrochemistry and anode optimization. Air-electrochemistry involves the interactions among electrolytes, cathodes, and air, which is a complex issue to understand. The search for stable electrolytes is first introduced because at the early age of its development, the use of incompatible Li-ion battery electrolytes leads to some misunderstandings and troubles in the advances of Li–air batteries. After finding suitable electrolytes for Li–air batteries, the fundamental research in the reaction mechanism starts to boom, and the performance has achieved great improvement. Then, air electrode engineering is introduced to give a general design principle. Examples of carbon-based cathodes and all-metal cathodes are discussed. In addition, to understand the influence of air components on Li–air batteries, the electro-activity of N2 has been tested and the role of CO2 in Li–O2/CO2 has been refreshed. Following this, the strategies for anode optimization, including constructing artificial films, introducing hydrophobic polymer electrolytes, adding electrolyte additives, and designing alloy anodes, have been discussed. Finally, we advocate researchers in this field to conduct cell level optimizations and consider their application scenarios to promote the commercialization of Li–air batteries in the near future.
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Polydopamine (PDA), which is biodegradable and is derived from naturally occurring products, can be employed as an electrode material, wherein controllable partial oxidization plays a key role in ...balancing the proportion of redox‐active carbonyl groups and the structural stability and conductivity. Unexpectedly, the optimized PDA derivative endows lithium‐ion batteries (LIBs) or sodium‐ion batteries (SIBs) with superior electrochemical performances, including high capacities (1818 mAh g−1 for LIBs and 500 mAh g−1 for SIBs) and good stable cyclabilities (93 % capacity retention after 580 cycles for LIBs; 100 % capacity retention after 1024 cycles for SIBs), which are much better than those of their counterparts with conventional binders.
Mussel power: A polydopamine‐derived material can act as both electrode and binder material for lithium‐ion and sodium‐ion batteries, and exhibits superior electrochemical performances including high capacity and stable cyclability. The material is synthesized by the oxidative polymerization of dopamine, which is both naturally occurring and biodegradable.
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Lithium metal is the only anode material that can enable the Li−O2 battery to realize its high theoretical energy density (≈3500 Wh kg−1). However, the inherent uncontrolled dendrite growth and ...serious corrosion limitations of lithium metal anodes make it experience fast degradation and impede the practical application of Li−O2 batteries. Herein, a multifunctional complementary LiF/F‐doped carbon gradient protection layer on a lithium metal anode by one‐step in situ reaction of molten Li with poly(tetrafluoroethylene) (PTFE) is developed. The abundant strong polar C‐F bonds in the upper carbon can not only act as Li+ capture site to pre‐uniform Li+ flux but also regulate the electron configuration of LiF to make Li+ quasi‐spontaneously diffuse from carbon to LiF surface, avoiding the strong Li+‐adhesion‐induced Li aggregation. For LiF, it can behave as fast Li+ conductor and homogenize the nucleation sites on lithium, as well as ensure firm connection with lithium. As a result, this well‐designed protection layer endows the Li metal anode with dendrite‐free plating/stripping and anticorrosion behavior both in ether‐based and carbonate ester‐based electrolytes. Even applied protected Li anodes in Li−O2 batteries, its superiority can still be maintained, making the cell achieve stable cycling performance (180 cycles).
A gradient LiF/F‐doped carbon protection layer with synergistic functions of homogenizing Li+ flux, fast Li+ diffusion ability, and low Li+ diffusion barrier is prepared by a one‐step in situ reaction to solve the challenges relating to unstable lithium anode in Li–O2 batteries, and, as a result, significantly boost the cycling stability of the Li–O2 batteries.
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Oxygen evolution: A 3D nickel foam/porous carbon/anodized nickel electrode was designed for the oxygen evolution reaction (see picture). The conductive porous carbon membrane, which is derived from a ...zeolite imidazolate framework, plays a key role as an interlayer to both protect the inner instable Ni foam and support the outermost oxygen‐evolving Ni catalyst layer.
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