A Flexible and Safe Planar Zinc‐Ion Micro‐Battery with Ultrahigh Energy Density Enabled by Interfacial Engineering for Wearable Sensing Systems

Abstract

Aqueous zinc-ion micro-batteries (ZIMBs) have attracted considerable attention owing to their reliable safety, low cost, and great potential for wearable devices. However, current ZIMBs still suffer from various critical issues, including short cycle life, poor mechanical stability, and inadequate energy density. Herein, the fabrication of flexible planar ZIMBs with ultrahigh energy density by interfacial engineering in the screen-printing process based on highperformance MnO 2 -based cathode materials is reported. The Ce-doped MnO 2 (Ce-MnO 2 ) exhibits significantly enhanced capacity (389.3 mAh g −1 ), considerable rate capability and admirable cycling stability than that of the pure MnO 2 . Importantly, the fabrication of micro-electrodes with ultrahigh mass loading of Ce-MnO 2 (24.12 mg cm −2 ) and good mechanical stability is achieved through optimizing the interfacial bonding between different printed layers. The fabricated planar ZIMBs achieve a record high capacity (7.21 mAh cm −2 or 497.31 mAh cm −3 ) and energy density (8.43 mWh cm −2 or 573.45 mWh cm −3 ), as well as excellent flexibility. Besides, a wearable self-powered sensing system for environmental monitoring is further demonstrated by integrating the planar ZIMBs with flexible solar cells and a multifunctional sensor array. This work sheds light on the development of high-performance planar ZIMBs for future self-powered and eco-friendly smart wearable electronics.

Multi-Channel Engineering of 3D Printed Zincophilic Anodes for Ultrahigh-Capacity and Dendrite-Free Quasi-Solid-State Zinc-Ion Microbatteries

“…At 0.3 mA cm –2 , areal device capacities reached 4.82, 7.93, and 11.93 mA h cm –2 for 1, 2, and 3 printing layers, respectively. The achieved device capacity values were superior to those of most reported Zn-based battery devices and even Li-based battery devices. − It can be observed that the 3DP-NiVO//NHCs@Zn battery exhibited a high energy density of up to 5.98 mW h cm –2 , which was superior to those of reported micro energy storage devices (Figure d). ,,− …”

Dynamic compensation of MnOOH to mitigate the irregular dissolution of MnO2in rechargeable aqueous Zn/MnO2batteries

“…3d), one pair of redox peak corresponding to the MnO 2 /MnOOH conversion reaction could be found in the Zn/MnO 2 battery with two types of electrolytes, which was consistent with the charge/discharge plateaus in galvanostatic charge/discharge curves (GCDs). 30–32 Meanwhile, the higher current density of Zn/MnO 2 batteries with Ce(SO 4 ) 2 additives in comparison with that without Ce(SO 4 ) 2 additives indicated a higher specific capacity, which was ascribed to the dynamic compensation mechanism (Fig. 3e–g).…”

Aqueous Batteries for Human Body Electronic Devices

“…Meanwhile, planar micro batteries are smaller and lighter in size and weight and more flexible, making them easier to wear to supply energy for wearable electronic devices (Figure 5f). 49 The preparation process of planar microcells usually involves the printing of highly conductive substances with inert properties as current collectors, such as graphene, Ag, Au, etc., in specific pattern onto flexible substrates (e.g., polyethylene terephthalate, PET) by screen printing. Subsequently, the inks containing the active material are printed on the cathodic and anodic current collectors, respectively, and then the electrolyte is added and the battery is encapsulated.…”

“…This also allows the electrode shape of the micro battery to be designed arbitrarily, providing an opportunity for the development of high-performance micro batteries. Meanwhile, planar micro batteries are smaller and lighter in size and weight and more flexible, making them easier to wear to supply energy for wearable electronic devices (Figure f) . The preparation process of planar microcells usually involves the printing of highly conductive substances with inert properties as current collectors, such as graphene, Ag, Au, etc., in specific pattern onto flexible substrates (e.g., polyethylene terephthalate, PET) by screen printing.…”

“…(f) Digital photograph of micro battery powering wearable sensing system. Reused with permission from ref . Copyright 2023 Wiley-VCH.…”