Spinel LiNi_0.5−xMn_1.5+xO₄ (LNMO) has attracted intensive interest for lithium-ion battery due to its high voltage and high energy density. However, severe capacity fade attributed to unstable surface structure has hampered its commercialization. Oxygen vacancies (OVs) tend to occur in the surface of the material and lead to surface structure reconstruction, which deteriorates the battery performance during electrochemical cycling. Here, we utilize high-temperature-shock (HTS) method to synthesize LNMO materials with fewer surface OVs. Rapid calcination drives lower surface OVs concentration, reducing the content of Mn³⁺ and surface reconstruction layers, which is beneficial to obtain a stable crystal structure. The LNMO material synthesized by HTS method delivers an initial capacity of 127 mAh·g⁻¹ at 0.1 C and capacity retention of 81.6% after 300 cycles at 1 C, and exhibits excellent performance at low temperature.

Graphite is a dominant anode material for lithium-ion batteries (LIBs) due to its outstanding electrochemical performance. However, slow lithium ion (Li⁺) kinetics of graphite anode restricts its further application. Herein, we report that high-temperature shock (HTS) can drive spent graphite (SG) into defect-rich recycled graphite (DRG) which is ideal for high-rate anode. The DRG exhibits the charging specific capacity of 323 mAh/g at a high current density of 2 C, which outperforms commercial graphite (CG, 120 mAh/g). The eminent electrochemical performance of DRG can be attributed to the recovery of layered structure and partial remaining defects of SG during ultrafast heating and cooling process, which can effectively reduce total strain energy, accelerate the phase transition in thermodynamics and improve the Li⁺ diffusion. This study provides a facile strategy to guide the re-graphitization of SG and design high performance battery electrode materials by defect engineering from the atomic level.

Despite the high energy density of lithium-rich (Li-rich) cathodes, their implementation is hampered by the unsatisfied rate capacity and poor cycling performance accompanied with substantial voltage decay. To address these issues, the hierarchical yolk-shell structured Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ cathodes (YK-LMNCO) was proposed and synthesized through a facile glycerol assisted solvothermal approach and the following lithiation process. Benefitting from the shortened lithium diffusion lengths and the enhanced tolerance to the large volume variation upon lithium ions intercalation/de-intercalation, the unique structure reciprocates an initial coulombic efficiency of 85.8%, an outstanding capacity retention rate of 89.1% after cycling at 2.0 C for 200 cycles with a minor voltage drop, and a capacity retention rate of 93.8% after cycling at 10.0 C for 500 cycles, 85.2% for 1,000 cycles. When assembled with graphite as anode, the YK-LMNCO//graphite full cell shows a remarkable capacity retention rate of 87.2% after cycling at 5.0 C for 50 cycles. Our facile strategy for constructing the yolk-shell structured Li-rich cathodes with high capacity and voltage stability sheds light on synthesizing other lithium storage materials.

Although single-particle cryogenic electron microscopy (cryo-EM) has been applied extensively for elucidating many crucial biological mechanisms at the molecular level, this technique still faces critical challenges, the major one of which is to prepare the high-quality cryo-EM specimen. Aiming to achieve a more reproducible and efficient cryo-EM specimen preparation, novel supporting films including graphene-based two-dimensional materials have been explored in recent years. Here we report a robust and simple method to fabricate EM grids coated with single- or few-layer reduced graphene oxide (RGO) membrane in large batch for high-resolution cryo-EM structural determination. The RGO membrane has decreased interlayer space and enhanced electrical conductivity in comparison to regular graphene oxide (GO) membrane. Moreover, we found that the RGO supporting film exhibited nice particle-absorption ability, thus avoiding the air–water interface problem. More importantly, we found that the RGO supporting film is particularly useful in cryo-EM reconstruction of sub-100-kDa biomolecules at near-atomic resolution, as exemplified by the study of RBD-ACE2 complex and other small protein molecules. We envision that the RGO membranes can be used as a robust graphene-based supporting film in cryo-EM specimen preparation.

Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction (OER) and the impairment of chlorine electrochemistry at anode. Herein, we report a heterostructure of Ni₃S₂ nanoarray with secondary Fe-Ni(OH)₂ lamellar edges that exposes abundant active sites towards seawater oxidation. The resultant Fe-Ni(OH)₂/Ni₃S₂ nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater. It only requires an overpotential of 269 mV to afford a current density of 10 mA·cm⁻² and the Tafel slope is as low as 46 mV·dec⁻¹. The 27-hour chronopotentiometry operated at high current density of 100 mA·cm⁻² shows negligible deterioration, suggesting good stability of the Fe-Ni(OH)₂/Ni₃S₂@NF electrode. Faraday efficiency for oxygen evolution is up to ~ 95%, revealing decent selectivity of the catalyst in saline water. Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites. The density functional theory (DFT) calculations indicate that the OER has lower theoretical overpotential than Cl₂ evolution reaction in Fe sites, which is contrary to that of Ni sites. The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.