The galvanostatic lithiation/sodiation voltage profiles of hard carbon anodes are simple, with a sloping drop followed by a plateau. However, a precise understanding of the corresponding redox sites and storage mechanisms is still elusive, which hinders further development in commercial applications. Here, a comprehensive comparison of the lithium‐ and sodium‐ion storage behaviors of hard carbon is conducted, yielding the following key findings: 1) the sloping voltage section is presented by the lithium‐ion intercalation in the graphitic lattices of hard carbons, whereas it mainly arises from the chemisorption of sodium ions on their inner surfaces constituting closed pores, even if the graphitic lattices are unoccupied; 2) the redox sites for the plateau capacities are the same as those for the closed pores regardless of the alkali ions; 3) the sodiation plateau capacities are mostly determined by the volume of the available closed pore, whereas the lithiation plateau capacities are primarily affected by the intercalation propensity; and 4) the intercalation preference and the plateau capacity have an inverse correlation. These findings from extensive characterizations and theoretical investigations provide a relatively clear elucidation of the electrochemical footprint of hard carbon anodes in relation to the redox mechanisms and storage sites for lithium and sodium ions, thereby providing a more rational design strategy for constructing better hard carbon anodes.

Despite the recent attention for Li metal anode (LMA) with high theoretical specific capacity of ≈3860 mA h g−1, it suffers from not enough practical energy densities and safety concerns originating from the excessive metal load, which is essential to compensate for the loss of Li sources resulting from their poor coulombic efficiencies (CEs). Therefore, the development of high‐performance LMA is needed to realize anode‐minimized Li metal batteries (LMBs). In this study, high‐performance LMAs are produced by introducing a hierarchically nanoporous assembly (HNA) composed of functionalized onion‐like graphitic carbon building blocks, several nanometers in diameter, as a catalytic scaffold for Li‐metal storage. The HNA‐based electrodes lead to a high Li ion concentration in the nanoporous structure, showing a high CE of ≈99.1%, high rate capability of 12 mA cm−2, and a stable cycling behavior of more than 750 cycles. In addition, anode‐minimized LMBs are achieved using a HNA that has limited Li content (≈0.13 mg cm−2), corresponding to 6.5% of the cathode material (commercial NCM622 (≈2 mg cm−2)). The LMBs demonstrate a feasible electrochemical performance with high energy and power densities of ≈510 Wh kgelectrode−1 and ≈2760 W kgelectrode−1, respectively, for more than 100 cycles.

A distinctive solid-solution potassium-ion intercalation behavior of disordered graphitic carbon materials was observed.

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The fingerprint recognition has been widely used for biometrics in mobile devices. Existing fingerprint sensors have already been commercialized in the field of mobile devices using primarily Si-based technologies. Recently, mutual-capacitive fingerprint sensors have been developed to lower production costs and expand the range of application using thin-film technologies. However, since the mutual-capacitive method detects the change of mutual capacitance, it has high ratio of parasitic capacitance to ridge-to-valley capacitance, resulting in low sensitivity, compared to the self-capacitive method. In order to demonstrate the self-capacitive fingerprint sensor, a switching device such as a transistor should be integrated in each pixel, which reduces a complexity of electrode configuration and sensing circuits. The oxide thin-film transistor (TFT) can be a good candidate as a switching device for the self-capacitive fingerprint sensor. In this work, we report a systematic approach for self-capacitive fingerprint sensor integrating Al-InSnZnO TFTs with field-effect mobility higher than 30 cm 2 /Vs, which enable isolation between pixels, by employing industry-friendly process methods. The fingerprint sensors are designed to reduce parasitic resistance and capacitance in terms of the entire system. The excellent uniformity and low leakage current (<10 −12 ) of the oxide TFTs allow successful capture of a fingerprint image.

3D-structured bifunctional MXene paper electrode (3D-BMPE), which has distinctive material properties, was fabricated to protect Al deposition/dissolution reactions with improved redox kinetics.

Bifunctional hybrid anodes (BHAs), which are both a high-performance active host material for lithium-ion storage as well as a guiding agent for homogeneous lithium metal nucleation and growth, exhibit significant potential as anodes for next-generation high-energy-density lithium-ion batteries (LIBs). In this study, sulfur-doped hard carbon nanosphere assemblies (S-HCNAs) were prepared through a hydrothermal treatment of a liquid organic precursor, followed by high-temperature thermal annealing with elemental sulfur for application as BHAs for LIBs. In a carbonate-based electrolyte containing fluoroethylene carbonate additive, the S-HCNAs showed high lithium-ion storage capacities in sloping as well as plateau voltage sections, good rate capabilities, and stable cyclabilities.In addition, high average Coulombic efficiencies (CEs) of ~96.9% were achieved for dual lithium-ion and lithium metal storage cycles. In the LIB full-cell tests with typical NCM811 cathodes, the S-HCNA-based BHAs containing ~400 mA h g −1 of excess lithium led to high energy and power densities of ~500 W h kg −1 and ~1695 W kg −1 , respectively, and a stable cycling performance with ~100% CEs was achieved.

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