COMMUNICATION (1 of 7)between safety and performance has been a challenge due to the use of intrinsically flammable organic electrolyte materials. In addition to the high level of recent interest in all-solid-state LIBs, [5][6][7][8] an alternative is to develop battery technologies that use aqueous electrolytes which are intrinsically safe. [9][10][11] Among candidate anode materials for aqueous batteries, Zn is the most active metal that is stable in water and also has one of the highest specific capacities. As an anode Zn has roughly three times the volumetric capacity (5854 mAh cm −3 ) compared to Li (2062 mAh cm −3 ). [12,13] When paired with an oxygen cathode, the theoretical volumetric energy density of a Zn-air battery (4400 Wh L −1 ) approaches that of a Li-S battery (5200 Wh L −1 ). Additional advantages of the Zn-air cell compared to the Li-S cell are that Zn is much more economical than Li [14][15][16] and the battery is safer due to absence of flammable organic liquid, making Zn-based batteries attractive candidates for electric vehicles and large-scale energy storage. There has been recent progress on rechargeable Zn anode materials in neutral or mildly acidic conditions that eliminate concerns of ZnO passivating the Zn surface. [17][18][19] In order for Zn-based aqueous batteries to have higher specific energy than state-of-the-art LIBs, however, an oxygen cathode must be used, [16] which favors alkaline electrolytes (e.g., KOH) to facilitate the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Although developing efficient ORR and OER electrocatalysts could lower the polarization and improve the round trip energy efficiency of Zn-air batteries, their reversibility is mainly limited by the Zn anode, which has received far less attention. [20][21][22][23][24][25] A deeply rechargeable zinc anode in lean alkaline electrolyte (a cell utilizing the minimum amount of electrolyte) is a critical step toward zinc air battery that has not been achieved yet. A few attempts have been made before. [26][27][28] However, to the best of our knowledge, all of the electrochemical data in past reports were obtained in beaker cells (Figure 1) with ZnO saturated electrolyte or a low depth of discharge (DOD), which raises several problems: (1) the amount of electrolyte exceeds the amount of electrode materials by ≈1000 times, which lowers the overall energy density and covers the problem of As an alternative to lithium-ion batteries, Zn-based aqueous batteries feature nonflammable electrolytes, high theoretical energy density, and abundant materials. However, a deeply rechargeable Zn anode in lean electrolyte configuration is still lacking. Different from the solid-to-solid reaction mechanism in lithium-ion batteries, Zn anodes in alkaline electrolytes go through a solid-solute-solid mechanism (Zn-Zn (OH) 4 2− -ZnO), which introduces two problems. First, discharge product ZnO on the surface prevents further reaction of Zn underneath, which leads to low utilization of active material and poor rec...

Wearable strain sensors that detect joint/muscle strain changes become prevalent at human–machine interfaces for full-body motion monitoring. However, most wearable devices cannot offer customizable opportunities to match the sensor characteristics with specific deformation ranges of joints/muscles, resulting in suboptimal performance. Adequate wearable strain sensor design is highly required to achieve user-designated working windows without sacrificing high sensitivity, accompanied with real-time data processing. Herein, wearable Ti3C2Tx MXene sensor modules are fabricated with in-sensor machine learning (ML) models, either functioning via wireless streaming or edge computing, for full-body motion classifications and avatar reconstruction. Through topographic design on piezoresistive nanolayers, the wearable strain sensor modules exhibited ultrahigh sensitivities within the working windows that meet all joint deformation ranges. By integrating the wearable sensors with a ML chip, an edge sensor module is fabricated, enabling in-sensor reconstruction of high-precision avatar animations that mimic continuous full-body motions with an average avatar determination error of 3.5 cm, without additional computing devices.

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An innovative anode material of lithium-ion battery, Li3VO4/Ti3C2Tx, was synthesized. The overall three-dimensional electronic and ionic transport pathways were formed in anode, which promoted both electron and ion transport during the lithiation and delithiation processes.