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.
The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O2), the vulnerability of conventional organic electrolytes and carbon cathodes towards ...reaction intermediates, especially O2−, and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li‐air battery. Even worse, the water and/or CO2 in air bring parasitic reactions and safety issues. Therefore, applying such systems in open‐air environment is challenging. Herein, contrary to previous assertions, we have found that CO2 can improve the stability of both anode and electrolyte, and a high‐performance rechargeable Li–O2/CO2 battery is developed. The CO2 not only facilitates the in situ formation of a passivated protective Li2CO3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O2−. Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li2CO3. The Li–O2/CO2 battery achieves a full discharge capacity of 6628 mAh g−1 and a long life of 715 cycles, which is even better than those of pure Li–O2 batteries.
CO2 can do: CO2 makes Li–O2 batteries more stable. On the anode side, CO2 can facilitate the formation of a protective and self‐healing Li2CO3 film, which can expel the H2O and aggressive intermediates during cycling. The cathode and electrolyte are also protected because the O2− intermediate is captured by CO2 to prevent the formation of 1O2.
Background and aims
Endoscopic diagnosis of early esophageal squamous cell cancer (ESCC) is complicated and dependent on operators' experience. This study aimed to develop an artificial intelligence ...(AI) model for automatic diagnosis of early ESCC.
Methods
Non‐magnifying and magnifying endoscopic images of normal/noncancerous lesions, early ESCC, and advanced esophageal cancer (AEC) were retrospectively obtained from Qilu Hospital of Shandong University. A total of 10,988 images from 5075 cases were chosen for training and validation. Another 2309 images from 1055 cases were collected for testing. One hundred and four real‐time videos were also collected to evaluate the diagnostic performance of the AI model. The diagnostic performance of the AI model was compared with endoscopists by magnifying images and the assistant efficiency of the AI model for novices was evaluated.
Results
The AI diagnosis for non‐magnifying images showed a per‐patient accuracy, sensitivity, and specificity of 99.5%, 100%, 99.5% for white light imaging, and 97.0%, 97.2%, 96.4% for optical enhancement/iodine straining images. Regarding diagnosis for magnifying images, the per‐patient accuracy, sensitivity, and specificity were 88.1%, 90.9%, and 85.0%. The diagnostic accuracy of the AI model was similar to experts (84.5%, P = 0.205) and superior to novices (68.5%, P = 0.005). The diagnostic performance of novices was significantly improved by AI assistance. When it comes to the diagnosis for real‐time videos, the AI model showed acceptable performance as well.
Conclusions
The AI model could accurately recognize early ESCC among noncancerous mucosa and AEC. It could be a potential assistant for endoscopists, especially for novices.
Sodium‐ion batteries (SIBs) are considered as promising alternatives to lithium‐ion batteries (LIBs) for large‐scale electrical‐energy‐storage applications due to the wide availability and the low ...cost of Na resources. Along with the avenues of research on flexible LIBs, flexible SIBs are now being actively developed as one of the most promising power sources for the emerging field of flexible and wearable electronic devices. Here, the recent progress on flexible electrodes based on metal substrates, carbonaceous substrates (i.e., graphene, carbon cloth, and carbon nanofibers), and other materials, as well as their applications in flexible SIBs, are summarized. Also, some future research directions for constructing flexible SIBs are proposed, with the aim of providing inspiration to the further development of advanced flexible SIBs.
Flexible sodium‐ion batteries (SIBs) are being actively developed as one of the most promising power sources for the emerging field of flexible and wearable electronic devices. The recent progress on flexible electrodes based on metal substrates, carbonaceous substrates, and other materials, is summarized, along with their applications in flexible SIBs.
Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy ...density of batteries is to search for high‐capacity electrode materials. According to the concept of energy quality, a high‐voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high‐capacity Li‐rich cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after‐treatment, and the specific energy is improved from 912 to 1033 Wh kg−1. The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.
Li‐ion batteries with high energy quality require a high capacity coupled with high operating voltage. This requires the electrode materials to not only have a high specific capacity but also a high discharge voltage for cathode materials and low charge voltage for anode materials.
Increasing energy density of Li-ion batteries (LiBs) along with fast charging capability are two key approaches to eliminate range anxiety and boost mainstream adoption of electric vehicles (EVs). ...Either the increase of energy density or of charge rate, however, heightens the risk of lithium plating and thus deteriorates cell life. The trilemma of fast charging, energy density and cycle life are studied systematically in this work utilizing a physics-based aging model with incorporation of both lithium plating and solid-electrolyte-interphase (SEI) growth. The model is able to capture the key feature of temperature-dependent aging behavior of LiBs, or more specifically, the existence of an optimal temperature with the longest cycle life. We demonstrate that this optimal temperature is a result of competition between SEI growth and lithium plating. Further, it is revealed that either the increase of charge rate or of energy density accelerates lithium plating induced aging. As such, the optimal temperature for cell life increases from ∼20 °C for a high-power cell at 1C charge to ∼35–45 °C with the increase of charge rate and/or energy density. It would be beneficial to further increase the charge temperature in order to enable robust fast charging of high energy EV cells.
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•Temperature-dependent aging behavior of Li-ion battery is studied numerically.•Overall aging rate depends on the competition of lithium plating and SEI growth.•The optimal temperature for cycle life increases with charge rate & energy density.•Raising charging temperature is an effective method to eliminating lithium plating.
To promote the development of high energy Li–O2 batteries, it is important to design and construct a suitable and effective oxygen‐breathing cathode. Herein, activated cobalt‐nitrogen‐doped carbon ...nanotube/carbon nanofiber composites (Co‐N‐CNT/CNF) as the effective cathodes for Li–O2 batteries are prepared by in situ chemical vapor deposition (CVD). The unique architecture of these electrodes facilitates the rapid oxygen diffusion and electrolyte penetration. Meanwhile, the nitrogen‐doped carbon nanotube/carbon nanofiber (N‐CNT/CNF) and Co/CoNx serve as reaction sites to promote the formation/decomposition of discharge product. Li–O2 batteries with Co‐N‐CNT/CNF cathodes exhibit superior electrochemical performance in terms of a positive discharge plateau (2.81 V) and a low charge overpotential (0.61 V). Besides, Li–O2 batteries also present a high discharge capacity (11512.4 mAh g−1 at 100 mA g−1), and a long cycle life (130 cycles). Meanwhile, the Co‐N‐CNT/CNF cathode also has an excellent flexibility, thus the assembled flexible battery with Co‐N‐CNT/CNF can work normally and hold a wonderful capacity rate under various bending conditions.
Activated cobalt‐nitrogen‐doped carbon nanotube/carbon nanofiber composites (Co‐N‐CNT/CNF) cathodes are prepared via in situ chemical vapor deposition. The Li–O2 batteries with these cathodes exhibit great performances. Meanwhile, Co‐N‐CNT/CNF cathodes are flexible, based on which the assembled flexible battery exhibits great performances and flexibility under various bending conditions.
Autonomous underwater vehicles (AUVs) are submersible underwater vehicles controlled by onboard computers. AUV formation is a cooperative control which focuses on controlling multiple AUVs to move in ...a group while executing tasks. In contrast to a single AUV, multi-AUV formation represents higher efficiency and better stability for many applications, such as oil and gas industries, hydrographic surveys, and military missions, etc. To achieve better formation, there are several key factors, including AUV performance, formation control, and communication capability. However, most studies in the field of AUV formation mainly focus on formation control methods. We observe that the research of communication capability and AUV performance of multiple AUV formation is still in an early stage. It is beneficial to researchers to present a comprehensive survey of the state of the art of AUV formation research and development. In this paper, we study AUV, formation control, and underwater acoustic communication capability in detail. We propose a classification framework with three dimensions, including AUV performance, formation control, and communication capability. This framework provides a comprehensive classification method for future AUV formation research. It also can be used to compare different methods and help engineers choose suitable formation methods for various applications. Moreover, our survey discusses formation architecture with communication constraints and we identify some common misconceptions and questionable research for formation control related to communication.
Oxygen‐redox of layer‐structured metal‐oxide cathodes has drawn great attention as an effective approach to break through the bottleneck of their capacity limit. However, reversible oxygen‐redox can ...only be obtained in the high‐voltage region (usually over 3.5 V) in current metal‐oxide cathodes. Here, we realize reversible oxygen‐redox in a wide voltage range of 1.5–4.5 V in a P2‐layered Na0.7Mg0.2Fe0.2Mn0.6□0.2O2 cathode material, where intrinsic vacancies are located in transition‐metal (TM) sites and Mg‐ions are located in Na sites. Mg‐ions in the Na layer serve as “pillars” to stabilize the layered structure during electrochemical cycling, especially in the high‐voltage region. Intrinsic vacancies in the TM layer create the local configurations of “□–O–□”, “Na–O–□” and “Mg–O–□” to trigger oxygen‐redox in the whole voltage range of charge–discharge. Time‐resolved techniques demonstrate that the P2 phase is well maintained in a wide potential window range of 1.5–4.5 V even at 10 C. It is revealed that charge compensation from Mn‐ and O‐ions contributes to the whole voltage range of 1.5–4.5 V, while the redox of Fe‐ions only contributes to the high‐voltage region of 3.0–4.5 V. The orphaned electrons in the nonbonding 2p orbitals of O that point toward TM‐vacancy sites are responsible for reversible oxygen‐redox, and Mg‐ions in Na sites suppress oxygen release effectively.
Na0.7Mg0.2Fe0.2Mn0.6□0.2O2 with native transitional metal (TM) vacancies is designed as a novel cathode material for sodium‐ion batteries. The TM vacancies lead to nonbonding O 2p orbitals in this material, pointing toward these vacancies triggering reversible whole‐voltage‐range oxygen redox during charge and discharge processes. This work provides new ideals for design of cathode materials in anionic redox chemistry.
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