Lithium nickel manganese cobalt oxide (NMC) cathodes are of great importance for the development of lithium ion batteries with high energy density. Currently, most commercially available NMC products are polycrystalline secondary particles, which are aggregated by anisotropic primary particles. Although the polycrystalline NMC particles have demonstrated large gravimetric capacity and good rate capabilities, the volumetric energy density, cycling stability as well as production adaptability are not satisfactory. Well-dispersed single-crystalline NMC is therefore proposed to be an alternative solution for further development of high-energy-density batteries. Various techniques have been explored to synthesize the single-crystalline NMC product, but the fundamental mechanisms behind these techniques are still fragmented and incoherent. In this manuscript, we start a journey from the fundamental crystal growth theory, compare the crystal growth of NMC among different techniques, and disclose the key factors governing the growth of single-crystalline NMC. We expect that the more generalized growth mechanism drawn from invaluable previous works could enhance the rational design and the synthesis of cathode materials with superior energy density.

Ni-rich layered LiNi x Mn y Co z O2 (NMC) cathodes for lithium-ion batteries are receiving a lot of attention owing to their promising large capacity, whereas the high content of Ni results in several issues including poor thermal stability and serious Li/Ni disorder. Although a little degree of the Li/Ni disorder may be beneficial for the structural stability of NMC cathodes and even migration of Li ions, a high degree of the Li/Ni disorder certainly deteriorates their electrochemical performances. Therefore, tuning the Li/Ni disorder is of great interest in the development of safer NMC cathodes with larger accessible capacity. Post-synthesis annealing is a facile and low-cost way to manipulate lattice defects, yet has not been utilized to optimize the Ni-rich NMC cathodes. In this work, we report that post-synthesis annealing can induce the competition between lattice ordering and structure decomposition. The thermal annealing promoted that lattice ordering would prevail until the decomposition of oxygen lattice. Once the annealing temperature reaches the critical temperature to form oxygen vacancies, Ni ions can easily migrate into the Li slab. The Li/Ni disorder can be facilely tuned through post-synthesis annealing to optimize the electrochemical performances of NMC cathodes.

Patchy colloidal nanoparticles are important for a broad range of applications, especially as building blocks for complex and functional structural materials, but the controllable generation of chemical patches on as-synthesized nanoparticles remains a challenge. This article describes a robust strategy for the scalable synthesis of highquality patchy nanoparticles in high yield and solid content. A simple thermal treatment of a mixture of gold nanoparticles and thiolterminated block-random copolymers in selected solvents produced a variety of patchy nanoparticles with a controlled morphology and number of polymeric patches (e.g., beanlike patch, one patch, two patches, three patches, multiple patches, and open-configuration patch). We show in experiments and simulations that the dynamic detachment/attachment of copolymers and the exchange of copolymers between the nanoparticle surface and free micelles in the solutionwhich are dictated by the architecture of copolymersgovern the formation of polymeric patches. This work not only offers an effective approach to patchy nanoparticles but also provides new insights into the phase behaviors of copolymers on nanoscale surfaces.

The posterior sucker of a leech represents a fascinating natural system that allows the leech to adhere to different terrains and substrates. However, the mechanism of adhesion and desorption has not yet to be elucidated. In order to better understand how the adhesion is performed, we analyzed the surface structure, adsorption movements, the muscles’ distribution, physical characteristics, and the adsorption force of the leech posterior suckers by experimental investigation. Three conclusions can be drawn based on the obtained experimental results. First, the adhesion by the posterior sucker is wet adhesion, because the surface of the posterior sucker is smooth and the sealing can only be achieved on wet surfaces. Second, the deformation texture, consisting of soft collagen tissues and highly ductile epidermal tissues, plays a key role in adhering to rough surfaces. Finally, the adhesion and desorption is achieved by the synergetic operation of six muscle fibers working in different directions. Concrete saying, directional deformation of the collagen/epithermal interface driven by spatially-distributed muscle fibers facilitates the excretion of fluids in the sucker venter, thus allowing liquid sealing. Furthermore, we found that the adhesion strength is directly related to the size of the contact surface which is generated and affected by the sucker deformation. Such an underlying physical mechanism offers potential cues for developing innovative bio-inspired artificial adhesion systems.

No abstract

Superoxide (O 2 − ) species play a crucial role in determining the charge kinetics for aprotic lithium−oxygen (Li−O 2 ) batteries. However, the growth of O 2 − -rich lithium peroxide (Li 2 O 2 ) is challenging since O 2 − is thermodynamically unfavorable and unstable in an O 2 atmosphere. Herein, we reported the synthesis of defective Li 2 O 2 with tunable O 2 − via K + doping. The K + dopants can successfully stabilize O 2 − species and induce the coordination of Li + with O 2 − , leading to increased Li vacancies. Compared to the pristine Li 2 O 2 , the as-prepared defective Li 2 O 2 can be charged at a lower overpotential in Li−O 2 batteries, which is ascribed to further increased Li vacancies contributed by the depotassiation process at the onset of the charge process. Our findings suggest a new strategy to better control O 2 − species in Li 2 O 2 by K + dopants and provide insights into the K + effects on charge mechanism in Li−O 2 batteries.

We report the synthesis of porous CoMoO nanorods and their applications in lithium oxygen (Li-O) and lithium ion (Li-ion) batteries. The unique porous structures of CoMoO nanorods can promote the permeation of electrolyte and benefit the transport of lithium ion. When employed as the cathode catalyst for a Li-O battery, CoMoO nanorods deliver an improved discharge capacity (4680 mA h g), lower charge potential and better cycle stability (41 cycles at 500 mA h g capacity limit) compared with the bare carbon. When employed as an anode in Li-ion batteries, CoMoO nanorods can retain a capacity of 603 mA h g after 300 cycles (400 mA g) and exhibit excellent rate capability.

Co3O4 surface functionalized porous carbon nanotubes were designed as an efficient cathode catalyst for Li–O2 batteries, with p-CNT to facilitate Li+ and O2 diffusion, and with Co3O4 to achieve a low charge overpotential.