layer (Brewer Science XHRIC-16) was spun on the sample at 4000 rpm for 30 s and oven prebaked at 175 C for 3 min. Photoresist (PR; Shipley 510A) was spun on the ARC at 4000 rpm and oven prebaked for 3 min at 95 C. IL with 355 nm third-harmonic YAG laser beam was used to produce periodic nanopatterns in the PR [9]. The angle between the two beams determined the 520 nm pattern period while the exposure dose and development time affected the detailed pattern shape. After exposure, the resist was post baked for 2 min at 110 C and developed using a MF-702 developer for 45 s followed by a rinse with deionized (DI) water. Pattern transfer was effected via lift-off of a thin gold film (~30 nm) that was deposited by electronbeam evaporation to form a hard mask and RIE of the underlying ARC and the silicon. Acetone was then used to liftoff the PR leaving a hard Au mask atop the ARC layer. Oxygen plasma was used to etch through the ARC for 3 min with the power of 50 W while a mixture of O 2 and CHF 3 (50:130) was used to etch Si for 3±6 min at a power of 150 W for an etch depth ranging from 30 to 200 nm. Finally, the ARC/Au layer was removed in an ultrasonic bath using piranha. The fabrication of periodic arrays of nanometer-scale cylindrical hole was performed on Si wafer coated with a 60 nm SiO 2 layer. The SiO 2 was thermally grown in a dry-O 2 oxidation furnace. The processing for fabrication 2D patterns was similar to that for groove structures except for double exposures and inductively coupled plasma (ICP) etching of the SiO 2 . After the samples were exposed with a first 1D grating, they were rotated 90 and exposed a second time to obtain 2D photoresist patterns (here posts for positive photoresist). After lift-off of a Au hard mask as above, an ICP system was next used to etch the SiO 2 in the regions where there was no Au hard mask in etching step. A mixture of Ar and CHF 3 (3:1) was used to etch SiO 2 for 2 min at the RF power of 500 W, bias of 150 W, and the pressure of 10 mtorr. The ICP etching could etch selectively SiO 2 with the mixture of Ar and CHF 3 in this case.Two particle sizes were investigated. Both are from Nissan Chemical Industries. Ltd. The larger silica particles (1 wt.-%,~pH 8.8) were prepared by diluting Snowtex ZL (40.9 wt.-%,~pH 9.6, 78 ±16 nm diameter [25]) with DI water. The smaller silica nanoparticles (1 wt.-%, pH 4.8) were prepared by diluting Snowtex OL (20 wt.-%,~pH 3, 50 ±13 nm diameter) with DI water. HCl or NH 4 OH were used to adjust the pH value of the water-based colloidal solutions. Before spin-coating, the treatment of an oxygen plasma RIE was used in order to ensure that the sample surface was hydrophilic. Next, the silica nanoparticle colloidal solution was spun onto the patterned samples. Images were obtained using field emission scanning electron microscopy (FE-SEM) (tilted at 45) at 30 kV with a 10 nm thick Au film to minimize charging.

Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high‐energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO‐based solid polymer electrolyte (DSM‐SPE) is exploited to achieve excellent electrochemical performance toward both the high‐voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM‐SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high‐voltage (≥4.3 V) LiCoO2/Li metal battery with PEO‐based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm−2 (0.25 mAh cm−2). Even under a high‐area capacity of 2 mAh cm−2, the profiles still maintain stable. The pouch cell with DSM‐SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM‐SPE‐based lithium metal battery.

great significance to develop electrochemical energy-storage technique and take advantage of sustainable and renewable energy. [1][2][3][4][5][6][7] Owing to natural abundance, wide availability, and low cost of sodium resources, sodium-ion batteries (SIBs) have been considered as one of most fascinating alternatives to the well-commercialized lithium-ion batteries for future large-scale stationary energy-storage systems with high adaptability and energy efficiency. [8][9][10][11][12][13] To develop satisfactory electrode materials in the future development of SIBs, continued research efforts have been devoted to screen new cathodes over the past few years. [14][15][16][17][18][19] Among a wide variety of cathode candidates including layered oxides, polyanion compounds, and Prussian blue analogues, layered oxide cathode materials have received significant attention because of the high voltage, low cost, and simple synthesis. Recently, research has made dramatic progress especially on manganese-based layered oxides such as zinc-doped Na 0.833 [Li 0.25 Mn 0.75 ]O 2 , Na 0.7 Mg 0.05 [Mn 0.6 Ni 0.2 Mg 0.15 ]O 2 , and Na 2.3 Cu 1.1 Mn 2 O 7−δ , which open new opportunities for developing high-performance cathode materials. [20][21][22][23][24] However, typical P2-type Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode material As one of the most promising cathode candidates for room-temperature sodium-ion batteries (SIBs), P2-type layered oxides face the challenge of simultaneously realizing high-rate performance while achieving long cycle life. Here, a stable Na 2/3 Ni 1/6 Mn 2/3 Cu 1/9 Mg 1/18 O 2 cathode material is proposed that consists of multiple-layer oriented stacking nanoflakes, in which the nickel sites are partially substituted by copper and magnesium, a characteristic of the material that is confirmed by multiscale scanning transmission electron microscopy and electron energy loss spectroscopy techniques. Owing to the optimal morphology structure modulation and chemical element substitution strategy, the electrode displays remarkable rate performance (73% capacity retention at 30C compared to 0.5C) and outstanding cycling stability in Na half-cell system couple with unprecedented full battery performance. The underlying thermal stability, phase stability, and Na + storage mechanisms are clearly elucidated through the systematical characterizations of electrochemical behaviors, in situ X-ray diffraction at different temperatures, and operando X-ray diffraction upon Na + deintercalation/intercalation. Surprisingly, a quasi-solid-solution reaction is switched to an absolute solid-solution reaction and a capacitive Na + storage mechanism is demonstrated via quantitative electrochemical kinetics calculation during charge/discharge process. Such a simple and effective strategy might reveal a new avenue into the rational design of excellent rate capability and long cycle stability cathode materials for practical SIBs.

Lithium carbonate is an unavoidable impurity at the cathode side.

Sodium‐ion batteries have gained much attention for their potential application in large‐scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the electrochemical performance of sodium‐ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high‐efficiency cathode sodiation compensation reagent, sodium oxalate (Na2C2O4), which possesses both a high theoretical capacity of 400 mA h g−1 and a capacity utilization as high as 99%, is proposed. The implementation of Na2C2O4 as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2‐Na2/3Ni1/3Mn1/3Ti1/3O2 cathode with Na2C2O4 as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg−1. This work can provide a new avenue for accelerating the development of SIFCs.