Owing to the development of aqueous rechargeable zinc‐ion batteries (ZIBs), flexible ZIBs are deemed as potential candidates to power wearable electronics. ZIBs with solid‐state polymer electrolytes ...can not only maintain additional load‐bearing properties, but exhibit enhanced electrochemical properties by preventing dendrite formation and inhibiting cathode dissolution. Substantial efforts have been applied to polymer electrolytes by developing solid polymer electrolytes, hydrogel polymer electrolytes, and hybrid polymer electrolytes; however, the research of polymer electrolytes for ZIBs is still immature. Herein, the recent progress in polymer electrolytes is summarized by category for flexible ZIBs, especially hydrogel electrolytes, including their synthesis and characterization. Aiming to provide an insight from lab research to commercialization, the relevant challenges, device configurations, and life cycle analysis are consolidated. As flexible batteries, the majority of polymer electrolytes exploited so far only emphasizes the electrochemical performance but the mechanical behavior and interactions with the electrode materials have hardly been considered. Hence, strategies of combining softness and strength and the integration with electrodes are discussed for flexible ZIBs. A ranking index, combining both electrochemical and mechanical properties, is introduced. Future research directions are also covered to guide research toward the commercialization of flexible ZIBs.
An insight from lab research to commercialization for flexible zinc‐ion batteries is provided by comprehensively reviewing the development of polymer electrolytes, relevant challenges and strategies, and device configurations. Aiming to quantify the feasibility for commercialization, a ranking index is proposed combining both electrochemical and mechanical properties. Future research directions are also covered to guide research toward commercialization.
With the rapid progress of wearable electronics, it is highly desirable to develop flexible power supplies, and significant progress has been thus made in making a variety of flexible batteries. Here ...the recent advances of flexible lithium ion batteries based on carbon nanomaterials have been carefully discussed from the viewpoint of material synthesis, structure design and property optimization. The remaining challenges and promising directions are highlighted to provide the clues for the future study in this booming field at end.
With the rapid progress of wearable electronics, it is highly desirable to develop flexible power supplies, and significant progress has been thus made in making a variety of flexible batteries. Here the recent advances of flexible lithium ion batteries based on carbon nanomaterials have been carefully discussed from the viewpoint of material synthesis, structure design and property optimization. The remaining challenges and promising directions are highlighted to provide the clues for the future study in this booming field at end. Display omitted
Electrochemical nitric oxide (NO) sensors are capable of real-time monitoring of intracranial NO concentration, which is crucial for understanding the functions of NO in the brain. However, ...traditional rigid electrochemical sensors used in the brain face the dilemma of low sensitivity and abnormal NO concentrations caused by neuroin-flammatory responses. Here, we report a highly sensitive and accurate electrochemical NO sensor that combines both physical and chemical adsorption capabilities for NO. The physical and chemical adsorption capabilities can be attributed to the high specific surface area and abundant carboxyl functional groups of the electrode, respectively. Besides, it is soft and matches the mechanical property of brain tissue, enabling an adaptable interface. The resulting NO sensor exhibits the highest reported sensitivity of 3245 pA nmol
−1
L, with a low detection limit of 0.1 nmol L
−1
. No significant inflammatory response or excess NO expression is observed after implantation, improving the detection accuracy. The sensor successfully captures NO fluctuations in the brain and enables simultaneous NO detection in multiple brain regions, facilitating research on NO physio-pathological actions in the brain.
Wearable sweat sensing technologies have received wide attention for personalized health monitoring with continuous and molecular‐level insight in a noninvasive manner. However, it remains ...significantly challenging to simultaneously capture a sufficient volume of sweat and achieve stable contact between electrodes and sweat, especially in a relatively mild sweating condition. Herein, a wearable electrochemical fabric sensor is developed by embroidering diversified sensing yarns with a multi‐ply cotton sheath and carbon nanotube‐based sensing fiber core into a super‐hydrophobic fabric substrate. The device allows for sweat enrichment among the core–sheath sensing yarn and reduce ineffective diffusion, thus remarkably increasing the sweat capture efficiency. As a result, only 0.5 µL of sweat is needed to achieve stable circuit connectivity, 1/20 of the lowest volume reported to date. The device also maintains a highly durable sensing performance, obtained even during dynamic deformation processes such as bending, twisting, and shaking. It can be further designed into an integrated sports shirt system, which can perform real‐time monitoring of multiple chemical information (e.g., glucose, Na+, K+, and pH) of sweat for users at the states of both intense exercise conditions such as badminton and relatively mild conditions like walking and eating.
A wearable electrochemical fabric sensor based on core‐sheath sensing yarns is developed, requiring only 0.5 µL of sweat to run. The performance is maintained stably under dynamic processes. An integrated system is further fabricated that could perform real‐time monitoring of the multiple chemical information in sweat for users at the states of intense exercise conditions and relatively mild conditions.
Mg‐air batteries are explored as the next‐generation power systems for wearable and implantable electronics as they could work stably in neutral electrolytes and are also biocompatible. However, high ...corrosion rate and low utilization of Mg anode largely impair the performance of Mg‐air battery with low discharge voltage, poor specific capacity and low energy density. Here, to the best of our knowledge, we first report a dual‐layer gel electrolyte to simultaneously solve the above two problems by preventing the corrosion of Mg anode and the production of dense passive layer, respectively. The resulting Mg‐air batteries produced an average specific capacity of 2190 mAh g−1 based on the total Mg anode (99.3 % utilization rate of Mg anode) and energy density of 2282 Wh kg−1 based on the total anode and air electrode, both of which are the highest among the reported Mg‐air batteries. Besides, our Mg‐air batteries could be made into a fiber shape, and they were flexible to work stably under various deformations such as bending and twisting.
A dual‐layer gel electrolyte was designed to simultaneously prevent the corrosion of Mg anode and production of the dense passive layer in a Mg‐air battery. The resulting Mg‐air battery exhibited a specific capacity of 2190 mAh g−1 based on total anodic weight and an energy density of 2282 Wh kg−1 based on the total weight of anode and air electrode. It was further made into a fiber shape with high flexibility.
To satisfy the rapid development of portable and wearable electronics, it is highly desired to make batteries with both high energy densities and flexibility. Although some progress has been made in ...recent decades, the available batteries share critical problems of poor energy storage capacity and low flexibility. Herein, we have developed a silicon–oxygen battery fiber with high energy density and ultra‐high flexibility by designing a coaxial architecture with a lithiated silicon/carbon nanotube hybrid fiber as inner anode, a polymer gel as middle electrolyte and a bare carbon nanotube sheet as outer cathode. The fiber showed a high energy density of 512 Wh kg−1 and could effectively work after bending for 20 000 cycles. These battery fibers have been further woven into flexible textiles for a large‐scale application.
A silicon–oxygen battery fiber with high energy density and ultra‐high flexibility has been created. The coaxial architecture of the fiber was obtained by using a lithiated silicon/carbon nanotube hybrid fiber as inner anode, a polymer gel as middle electrolyte and a carbon nanotube sheet as outer cathode.
To develop wearable and implantable bioelectronics accommodating the dynamic and uneven biological tissues and reducing undesired immune responses, it is critical to adopt batteries with matched ...mechanical properties with tissues as power sources. However, the batteries available cannot reach the softness of tissues due to the high Young's moduli of components (e.g., metals, carbon materials, conductive polymers, or composite materials). The fabrication of tissue‐like soft batteries thus remains a challenge. Here, the first ultrasoft batteries totally based on hydrogels are reported. The ultrasoft batteries exhibit Young's moduli of 80 kPa, perfectly matching skin and organs (e.g., heart). The high specific capacities of 82 mAh g−1 in all‐hydrogel lithium‐ion batteries and 370 mAh g−1 in all‐hydrogel zinc‐ion batteries at a current density of 0.5 A g−1 are achieved. Both high stability and biocompatibility of the all‐hydrogel batteries have been demonstrated upon the applications of wearable and implantable. This work illuminates a pathway for designing power sources for wearable and implantable electronics with matched mechanical properties.
All‐hydrogel batteries with Young's moduli of 80 kPa are designed to match the mechanical properties of the skin and the heart. They exhibit a high specific capacity of 370 mAh g−1 and maintains stability during dynamic deformation. High stability and biocompatibility are realized on the skin and in vivo, so these all‐hydrogel batteries are an ideal power supply for wearable and implantable bioelectronics.
Zinc (Zn) metal is considered the promising anode for “post‐lithium” energy storage due to its high volumetric capacity, low redox potential, abundant reserve, and low cost. However, extravagant Zn ...is required in present Zn batteries, featuring low Zn utilization rate and device‐scale energy/power densities far below theoretical values. The limited reversibility of Zn metal is attributed to the spontaneous parasitic reactions of Zn with aqueous electrolytes, that is, corrosion with water, passive by‐product formation, and dendrite growth. Here, a new ion‐selective polymer glue coated on Zn anode is designed, isolating the Zn anode from the electrolyte by blocking water diffusion while allowing rapid Zn2+ ion migration and facilitating uniform electrodeposition. Hence, a record‐high Zn utilization of 90% is realized for 1000 h at high current densities, in sharp contrast to much poorer cyclability (usually < 200 h) at lower Zn utilization (50–85%) reported to date. When matched with the vanadium‐based cathode, the resulting Zn‐ion battery exhibited an ultrahigh device‐scale energy density of 228 Wh kg−1, comparable to commercial lithium‐ion batteries.
Polymer glue is designed to simultaneously solve corrosion, passivation, and dendrite growth for zinc anodes. The modified zinc anode demonstrates 90% zinc utilization at 5 mA cm−2 for 1000 h. Full zinc‐ion batteries are made to show an ultrahigh energy density of 228 Wh kg−1 based on the total mass of electrodes, superior rate performance, and long lifespan.
Aqueous zinc-ion batteries (AZIBs) have the potential to be utilized in a grid-scale energy storage system owing to their high energy density and cost-effective properties. However, the dissolution ...of cathode materials and the irreversible extraction of preintercalated metal ions in the electrode materials restrict the stability of AZIBs. Herein, a cathode-stabilized ZIB strategy is reported based on a natural biomass polymer sodium alginate as the electrolyte coupling with a Na
preintercalated δ-Na
Mn
O
·1.31H
O cathode. The dissociated Na
in alginate after gelation directly stabilizes the cathodes by preventing the collapse of layered structures during charge processes. The as-fabricated ZIBs deliver a high capacity of 305 mA h g
at 0.1 A g
, 10% higher than the ZIBs with an aqueous electrolyte. Further, the hybrid polymer electrolyte possessed an excellent Coulombic efficiency above 99% and a capacity retention of 96% within 1000 cycles at 2 A g
. A detailed investigation combining
experiments uncovers the charge storage mechanism and the stability of assembled batteries, confirming the reversible diffusions of both Zn
and preintercalated Na
. A flexible device of ZIBs fabricated based on vacuum-assisted resin transfer molding possesses an outstanding performance of 160 mA h g
at 1 A g
, which illustrates their potential for wearable electronics in mass production.
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