Flexible strain sensors (FSSs) are essential components in intelligent systems, especially in soft robots, human sport monitoring, ect., but their scalable preparation remains a challenge. In this work, we first proposed and demonstrated a strategy to prepare FSS with a scalable and cost-effective papermaking procedure. Cellulose fibers from waste papers and conductive graphite were mixed and subject to a paper former (papermaking machine in laboratory), producing a strain sensitive paper with diameter of 20 cm in 10 min. With the scrips from the strain sensitive paper, the strain sensor was assembled showing good sensing performance for both bending (gauge factor (GF) = 27, response time of 360 ms) and twisting (GF = 26.5, response time of 440 ms) strains. It can be used in movement detections of soft matters (such as a plastic ruler), elbow joints of a puppet, and human fingers. The cost of the sensor was calculated as low as $0.00013, and the strain sensitive paper can be degraded in around 1 min in water under stirring. Furthermore, the strategy can be expanded to the sensor based on carbon black (CB), indicating a universality, which may pave a way for developing more intelligent materials and devices.

Flexible sensors (FSs) hold great potential in wearable and intelligent equipment, but the preparation of degradable and multimodal FSs is urgently demanded, which may simplify the sensor matrix and reduce electronic waste. Here in this work, a multimodal and degradable FS was fabricated by transferring laser-induced porous carbon onto starch film. The obtained sensor showed three modes that can detect strain (with gauge factor (GF) = 134.2, response time of 130 ms, and stability >1000 times), temperature (25–90 °C), and pressure (0–250 kPa). The sensor can be used for monitoring human motions, detection of spatial pressure, and multiple stimuli. More importantly, the sensor was demonstrated to be degradable in water, suggesting it is a “green” electronic device being free of electronic pollution. This kind of multimodal and degradable FS may find wide applications in health and sports monitoring, flexible electronics, artificial intelligence, and so on.

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Exploring new materials and methods to achieve high utilization of sulfur with lean electrolyte is still a common concern in lithium‐sulfur batteries. Here, high‐density oxygen doping chemistry is introduced for making highly conducting, chemically stable sulfides with a much higher affinity to lithium polysulfides. It is found that doping large amounts of oxygen into NiCo2S4 is feasible and can make it outperform the pristine oxides and natively oxidized sulfides. Taking the advantages of high conductivity, chemical stability, the introduced large Li–O interactions, and activated Co (Ni) facets for catalyzing Sn2–, the NiCo2(O–S)4 is able to accelerate the Li2S‐S8 redox kinetics. Specifically, lithium‐sulfur batteries using free‐standing NiCo2(O–S)4 paper and interlayer exhibit the highest capacity of 8.68 mAh cm–2 at 1.0 mA cm–2 even with a sulfur loading of 8.75 mg cm–2 and lean electrolyte of 3.8 µL g–1. The high‐density oxygen doping chemistry can be also applied to other metal compounds, suggesting a potential way for developing more powerful catalysts towards high performance of Li–S batteries.