In order to address power and energy demands of mobile electronics and electric cars, Li‐ion technology is urgently being optimized by using alternative materials. This article presents a review of ...our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr2O3, MnO) are studied. The formation of nano/micro core–shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO2 and LiMn2O4 was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO4 reveal that alkali metal ions and nitrogen doping into the LiFePO4 lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel.
Recent progress in anode and cathode materials for Li‐ion batteries is reviewed. Nanostructured materials, size effects, and efforts on improving cyclic performance, thermal and chemical stability, and theoretical simulations are discussed.
Sodium‐ion batteries (SIBs) have attracted more and more attention for scalable electrical energy storage due to the abundance and wide distribution of Na resources. However, the anode still remains ...a great challenge for the application of SIBs. Here the production of uniform hard carbon microtubes (HCTs) made from natural cotton through one simple carbonization process and their application as an anode are reported. The study shows that the electrochemical performance of the HCTs is seriously affected by the carbonization temperature due to the difference in their microstructure and heteroatomic content. The HCTs carbonized at 1300 °C deliver the highest reversible capacity of 315 mAh g−1 and good rate capability due to their unique tubular structure. This contribution not only provides a new approach for the preparation of hard carbon materials with unique tubular microstructure using natural inspiration, but it also deepens the fundamental understanding of the sodium storage mechanism.
A novel hard carbon material with microtube structure constructed from hollow fiber structure of cotton fiber by simple one‐step carbonization approach is presented. The electrochemical sodium storage difference of hard carbon microtubes with different carbonization temperature and the sodium storage mechanism are systematically investigated in this work.
Anode‐free designs can obtain the ultimate energy density of lithium metal batteries. However, without a continuous Li supply from the anode side, it is much more challenging to achieve high capacity ...retention with a competitive energy density. Here, the lifespan of an anode‐free Li metal battery is prolonged by applying an epitaxial induced plating current‐collector (E‐Cu). The functional layer on E‐Cu initiates Li storage by an alloying approach, forming an epitaxial induce layer, which exhibits speedy surface diffusion for of Li‐ions, resulting in the block like epitaxial growth of Li. Moreover, this alloying process also promotes the formation of a LiF‐rich solid electrolyte interphase (SEI), which is very useful for uniform Li plating. Due to the benefits of epitaxial Li plating and LiF‐rich SEI, the initial coulombic efficiency of the E‐Cu/Li asymmetric cell increases from 93.24 to 98.24%, and the capacity retention of anode‐free NCM811/E‐Cu pouch cell increases from 66 to 84% with a remarkable energy density of 420 Wh kg−1 in the condition of limited electrolyte addition (E/C ratio of 2 g Ah−1). This strategy is promising in the development of high energy batteries in extending their lifespans.
An epitaxial induced plating current‐collector (E‐Cu) is applied in anode‐free lithium metal batteries (AF‐LMB) to extend their lifespan. The functional layer on E‐Cu initiates Li storage by an alloying approach, forming an epitaxial induced layer and a LiF‐rich solid electrolyte interphase, resulting in the efficient block like epitaxial growth of Li. The lifespan of AF‐LMB is also significantly improved.
Disordered carbons have captured extensive interest as anode materials for Na‐ion batteries (NIBs) due to the abundant resources, competitive specific capacity, and low cost. Here, a facile strategy ...of pre‐oxidation is successfully adopted to tune the microstructure of carbon anode to facilitate sodium storage. Pitch is selected as the low‐cost and high carbon yield precursor. An easy pre‐oxidation treatment in air can enable pitch to realize an effective structural conversion from ordered to disordered at further carbonization processes. Compared with the carbonized pristine pitch, the carbonized pre‐oxidation pitch increases the carbon yield from 54 to 67%, the sodium storage capacity from 94.0 to 300.6 mAh g−1, and the initial Coulombic efficiency from 64.2 to 88.6%. Experiment results reveal that the introduction of oxygen based functional groups is the key to achieve the highly disordered structure, not only ensuring the cross‐linkage during low‐temperature pre‐oxidation process but also suppressing the carbon structure from melting and rearranging in the high‐temperature carbonization process. Most importantly, this facile pre‐oxidation strategy can also be extended to other carbon precursors to facilitate the low‐cost and high‐performance disordered carbon anodes for NIBs and beyond.
A disordered carbon anode for Na‐ion batteries with both low cost and high performance is achieved via a simple pre‐oxidation of pitch in air followed by high‐temperature carbonization, during which the electrochemical behavior is modulated from possessing only a sloping region to featuring both sloping and plateau regions and a threefold capacity improvement is attained through this microstructure tuning.
Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge ...volume change during cycling. Although two-dimensional silicon-based materials show significantly improved performance, flexible synthesis of such materials is still a challenge. In this work, silicon-based nanosheets with a multilayer structure are synthesized for the first time by a topochemical reaction. The morphology and oxidation state of these nanosheets can be controlled by appropriate choice of reaction media and oxidants. Benefiting from the hierarchical structure and ultrathin size, when the silicon-based nanosheets are employed as anodes they exhibit a charge （delithiation） capacity of 800 mAh/g after 50 cycles with a maximum coulombic efficiency of 99.4% and good rate performance （647 mAh/g at 1 A/g）. This work demonstrates a novel method for preparing nanosheets not only for lithium ion batteries but also having various potential applications in other fields, such as catalysts, electronics and photonics.
The accurate early diagnosis of colorectal cancer significantly relies on the precise segmentation of polyps in medical images. Current convolution-based and transformer-based segmentation methods ...show promise but still struggle with the varied sizes and shapes of polyps and the often low contrast between polyps and their background. This research introduces an innovative approach to confronting the aforementioned challenges by proposing a Dual-Channel Hybrid Attention Network with Transformer (DHAFormer). Our proposed framework features a multi-scale channel fusion module, which excels at recognizing polyps across a spectrum of sizes and shapes. Additionally, the framework’s dual-channel hybrid attention mechanism is innovatively conceived to reduce background interference and improve the foreground representation of polyp features by integrating local and global information. The DHAFormer demonstrates significant improvements in the task of polyp segmentation compared to currently established methodologies.
Aggressive chemistry involving Li metal anode (LMA) and high-voltage LiNi
Mn
Co
O
(NCM811) cathode is deemed as a pragmatic approach to pursue the desperate 400 Wh kg
. Yet, their implementation is ...plagued by low Coulombic efficiency and inferior cycling stability. Herein, we propose an optimally fluorinated linear carboxylic ester (ethyl 3,3,3-trifluoropropanoate, FEP) paired with weakly solvating fluoroethylene carbonate and dissociated lithium salts (LiBF
and LiDFOB) to prepare a weakly solvating and dissociated electrolyte. An anion-enrichment interface prompts more anions' decomposition in the inner Helmholtz plane and higher reduction potential of anions. Consequently, the anion-derived interface chemistry contributes to the compact and columnar-structure Li deposits with a high CE of 98.7% and stable cycling of 4.6 V NCM811 and LiCoO
cathode. Accordingly, industrial anode-free pouch cells under harsh testing conditions deliver a high energy of 442.5 Wh kg
with 80% capacity retention after 100 cycles.
A novel single lithium‐ion (Li‐ion) conducting polymer electrolyte is presented that is composed of the lithium salt of a polyanion, ...poly(4‐styrenesulfonyl)(trifluoromethyl(S‐trifluoromethylsulfonylimino)sulfonyl)imide (PSsTFSI−), and high‐molecular‐weight poly(ethylene oxide) (PEO). The neat LiPSsTFSI ionomer displays a low glass‐transition temperature (44.3 °C; that is, strongly plasticizing effect). The complex of LiPSsTFSI/PEO exhibits a high Li‐ion transference number (tLi+=0.91) and is thermally stable up to 300 °C. Meanwhile, it exhibits a Li‐ion conductivity as high as 1.35×10−4 S cm−1 at 90 °C, which is comparable to that for the classic ambipolar LiTFSI/PEO SPEs at the same temperature. These outstanding properties of the LiPSsTFSI/PEO blended polymer electrolyte would make it promising as solid polymer electrolytes for Li batteries.
A super‐delocalized polyanion is used for a single lithium‐ion conducting polymer electrolyte. The neat LiPSsTFSI ionomer displays a low glass‐transition temperature (44.3 °C), and its blended polymer electrolyte of the LiPSsTFSI/PEO exhibits a high Li‐ion transference number (tLi+=0.91) and high ionic conductivities of individual Li+ cations, which are comparable to those for the classic ambipolar LiTFSI/PEO SPEs above 70 °C (the melting point).
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