Substantial effort has been devoted to both scientific and technological developments of wearable, flexible, semitransparent, and sensing electronics (e.g., organic/perovskite photovoltaics, organic thin‐film transistors, and medical sensors) in the past decade. The key to realizing those functionalities is essentially the fabrication of conductive electrodes with desirable mechanical properties. Conductive polymers (CPs) of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have emerged to be the most promising flexible electrode materials over rigid metallic oxides and play a critical role in these unprecedented devices as transparent electrodes, hole transport layers, interconnectors, electroactive layers, or motion‐sensing conductors. Here, the current status of research on PEDOT:PSS is summarized including various approaches to boosting the electrical conductivity and mechanical compliance and stability, directly linked to the underlying mechanism of the performance enhancements. Along with the basic principles, the most cutting edge‐progresses in devices with PEDOT:PSS are highlighted. Meanwhile, the advantages and plausible problems of the CPs and as‐fabricated devices are pointed out. Finally, new perspectives are given for CP modifications and device fabrications. This work stresses the importance of developing CP films and reveals their critical role in the evolution of these next‐generation devices featuring wearable, deformable, printable, ultrathin, and see‐through characteristics.

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g−1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g−1 still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

Defects and their interactions in crystalline solids often underpin material properties and functionality 1 as they are decisive for stability 1-5 , result in enhanced diffusion 6 , and act as a reservoir of vacancies 7 . Recently, lithium-rich layered oxides have emerged among the leading candidates for the next-generation energy storage cathode material, delivering 50 % excess capacity over commercially used compounds. Oxygen-redox reactions are believed to be responsible for the excess capacity 8 , however, voltage fading has prevented commercialization of these new materials. Despite extensive research the understanding of the mechanisms underpinning oxygen-redox reactions and voltage fade remain incomplete. Here, using operando three-dimensional Bragg coherent diffractive imaging 2,9 , we directly observe nucleation of a mobile dislocation network in nanoparticles of lithium-rich layered oxide material. Surprisingly, we find that dislocations form more readily in the lithium-rich layered oxide material as compared with a conventional layered oxide material, suggesting a link between the defects and the

Since the commercialization of lithium‐ion batteries (LIBs) in the early 1990s, tin (Sn), antimony (Sb), and germanium (Ge)‐based anodes have attracted considerable research interest as promising candidates for next‐generation LIBs due to their high theoretical capacities, suitable operating voltages, and natural abundance. Additionally, the awareness of limited global lithium sources promoted the renaissance of sodium‐ion batteries (SIBs) in recent years. Sn, Sb, and Ge can electrochemically alloy with sodium and are regarded as promising anode candidates for high‐performance SIBs. However, these alloying/dealloying anodes suffer severe volume expansion during lithiation or sodiation processes, which is one of the biggest obstacles toward practical applications. In order to solve this problem, several strategies are developed including reducing the absolute size of particles, creating interior void space, and introducing buffer media. After more than two decades' efforts, the electrochemical performance of Sn, Sb, and Ge‐based anodes is significantly improved. Considerable studies about Sn, Sb, and Ge‐based anodes are summarized in a chronicle perspective and the brief development histories of the three anodes are outlined. With this unique review, light will be shed on the future trends of the studies on the Sn, Sb, and Ge‐based anodes for advanced rechargeable batteries.

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Porous silicon has found wide applications in many different fields including catalysis and lithium-ion batteries. Three-dimensional hierarchical macro-/mesoporous silicon is synthesized from zero-dimensional Stöber silica particles through a facile and scalable magnesiothermic reduction process. By systematic structure characterization of the macro-/mesoporous silicon, a self-templating mechanism governing the formation of the porous silicon is proposed. Applications as lithium-ion battery anode and photocatalytic hydrogen evolution catalyst are demonstrated. It is found that the macro-/mesoporous silicon shows significantly improved cyclic and rate performance over the commercial nanosized and micrometer-sized silicon particles. After 300 cycles at 0.2 A g, the reversible specific capacity is still retained as much as 959 mAh g with a high mass loading density of 1.4 mg cm. With the large current density of 2 A g, a reversible capacity of 632 mAh g is exhibited. The coexistence of both macro- and mesoporous structures is responsible for the enhanced performance. The macro-/mesoporous silicon also shows superior catalytic performance for photocatalytic hydrogen evolution compared to the silicon nanoparticles.

Metal-ion doping can improve the electrochemical performance of Na 3 V 2 (PO 4 ) 3 . However, the reason for the enhanced electrochemical performance and the effects of cation doping on the structure of Na 3 V 2 (PO 4 ) 3 have yet been probed. Herein, Mg 2+ is doped into Na 3 V 2 (PO 4 ) 3 /C according to the firstprinciples calculation. The results indicate that Mg 2+ prefers to reside in the V site and an extra electrochemical active Na + is introduced to the Na 3 V 2 (PO 4 ) 3 /C crystal to maintain the charge balance. The distribution of Mg 2+ in the particle of Na 3 V 2 (PO 4 ) 3 /C is further studied by electrochemical impedance spectroscopy. We find that the highest distribution of Mg 2+ on the surface of the particles leads to facile surface electrochemical reactions for Mg 2+doped samples, especially at high rates. .chemmater.7b03903.The crystal structure of Na 3 V 2 (PO 4 ) 3 , the theoretical ratio of Na, V, Mg, and P when the doped site is V/Na site, ICP results for Mg 2+ -doped Na 3 V 2 (PO 4 ) 3 samples, sodium diffusion coefficients of Na 3 V 2 (PO 4 ) 3 /C and Na 3.05 V 1.95 Mg 0.05 (PO 4 ) 3 /C at different temperatures, SEM image of Na 3 V 2 (PO 4 ) 3 and STEM-HADDF images, and EDS line scan results ofNa 3.05 V 1.95 Mg 0.05 (PO 4 ) 3 /C sample (PDF)