Soft carbon has attracted tremendous attention as an anode in rocking‐chair batteries owing to its exceptional properties including low‐cost, tunable interlayer distance, and favorable electronic conductivity. However, it fails to exhibit decent performance for sodium‐ion storage owing to difficulties in the formation of sodium intercalation compounds. Here, microporous soft carbon nanosheets are developed via a microwave induced exfoliation strategy from a conventional soft carbon compound obtained by pyrolysis of 3,4,9,10‐perylene tetracarboxylic dianhydride. The micropores and defects at the edges synergistically leads to enhanced kinetics and extra sodium‐ion storage sites, which contribute to the capacity increase from 134 to 232 mAh g−1 and a superior rate capability of 103 mAh g−1 at 1000 mA g−1 for sodium‐ion storage. In addition, the capacitance‐dominated sodium‐ion storage mechanism is identified through the kinetics analysis. The in situ X‐ray diffraction analyses are used to reveal that sodium ions intercalate into graphitic layers for the first time. Furthermore, the as‐prepared nanosheets can also function as an outstanding anode for potassium‐ion storage (reversible capacity of 291 mAh g−1) and dual‐ion full cell (cell‐level capacity of 61 mAh g−1 and average working voltage of 4.2 V). These properties represent the potential of soft carbon for achieving high‐energy, high‐rate, and low‐cost energy storage systems.

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Prussian blue analogues have attracted growing attention as the positive electrode materials in rechargeable potassium-ion batteries (KIBs) due to the intrinsic open frameworks and high theoretical capacities. However, the bulk synthesized Prussian blue which is accompanied by aggregation inevitably results in the limited K+ ion mobility and suppressed potassium storage performance. In this work, ultrathin nanosheet-assembled hierarchical Prussian blue materials (K1.4Fe4[Fe­(CN)6]3) are synthesized via a facile dissolution-recrystallization strategy. On the strength of this architecture, the positive electrode displays both high rate (71 and 24.9 mAh g–1 at 50 and 600 mA g–1) and long life-span properties (75.2% of the primal capacity retained after 100 cycles) for potassium storage. The enhanced diffusion kinetics and structural stability are further demonstrated through the galvanostatic intermittent titration technique analysis and ex-situ X-ray diffraction. Our work provides a new nanostructuring strategy for improving the potassium storage in intercalation electrodes.

Complementary electrochromic devices (ECDs) composed of WO3 and NiO electrodes have wide applications in smart windows. However, they have poor cycling stability due to ion-trapping and charge mismatch between electrodes, which limits their practical application. In this work, we introduce a partially covered counter electrode (CE) composed of NiO and Pt to achieve good stability and overcome the charge mismatch based on our structure of electrochromic electrode/Redox/catalytic counter electrode (ECM/Redox/CCE). The device is assembled using a NiO-Pt counter electrode with WO3 as the working electrode, and PC/LiClO4 containing a tetramethylthiourea/tetramethylformaminium disulfide (TMTU/TMFDS2+) redox couple as the electrolyte. The partially covered NiO-Pt CE-based ECD exhibits excellent EC performance, including a large optical modulation of 68.2% at 603 nm, rapid switching times of 5.3 s (coloring) and 12.8 s (bleaching), and a high coloration efficiency of 89.6 cm2·C−1. In addition, the ECD achieves a good stability of 10,000 cycles, which is promising for practical application. These findings suggest that the structure of ECC/Redox/CCE could overcome the charge mismatch problem. Moreover, Pt could enhance the Redox couple’s electrochemical activity for achieving high stability. This research provides a promising approach for the design of long-term stable complementary electrochromic devices.

Aqueous electrolytes possess non-combustible and eco-friendly features compared to organic electrolytes, leading them to be more suitable for application in smart windows for daily use. However, limited by the narrow electrochemical window of water (1.23 V), its use in conventional electrochromic devices (ECDs) would result in irreversible performance loss, which arises from decomposition caused by high voltage. Here, we propose a synergistic scheme combining a redox couple-catalytic counter electrode (RC-CCE) strategy with protons as guest ions. With the help of the intelligent matching of the reaction potentials of the RC and amorphous WO 3 electrochromic electrodes and the highly active and fast kinetic features of protons, it successfully reduces the working voltage range of the device to 1.1 V. The assembled HClO 4 -ECD can possess an overall modulation rate (350−1200 nm) of 0.43 and 0.94 at −0.1 and −0.7 V, respectively, and a modulation of 66.8% at 600 nm at −0.7 V. Moreover, compared with other guest ions, the proton-based ECD exhibits higher coloration efficiency, a broader color modulation capability, and better stability. In addition, the house model equipped with the proton-based ECD effectively blocks solar radiation, which provides a potential solution for the design of aqueous smart windows.

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