High performance, environmentally benign and integratable Zn//MnO2 microbatteries

With the explosive development of wearable electronics and the Internet of Things (IoT), it is highly desirable to develop miniaturized power sources with high performance, low-cost, environmental friendliness and integratable characteristics. Rechargeable microbatteries (MBs) can be used as the main power sources of future miniaturized wearable electronics, which have drawn broad attention recently. However, ever-reported MBs, such as micro-lithium batteries, have intrinsic safety hazards and environmental threats, and are not fully compatible with the green initiative of the IoT. Here, we report aqueous Zn//MnO2 MBs, with the merits of green, low cost and sustainability. By using a simple and scalable fabrication strategy, Zn//MnO2 MBs constructed with a three-dimensional (3D) MnO2@nickel nanocone array (NCA) cathode, a Zn@NCA anode, and a mild aqueous electrolyte containing ZnSO4 and MnSO4 can be prepared on a large scale. The as-prepared Zn//MnO2 MB reveals a superior capacity of 53.5 μA h cm−2 μm−1 at 1 C rate and a working voltage of 1.4 V. Moreover, it achieves a superior volumetric energy density of 71.3 μW h cm−2 μm−1, together with a peak power density of 1621.4 μW cm−2 μm−1, substantially higher than those of the reported lithium-ion MBs. Such an ultrathin (74 μm in thickness), lightweight (30 mg per unit) and flexible Zn//MnO2 MB component can power three pieces of LEDs. Last but not least, the fabrication strategy of our Zn//MnO2 MBs is fully compatible with flexible electronic fabrication processes. For instance, we have demonstrated that these Zn//MnO2 MBs could share the same fabrication process platform with radio frequency identification (RFID) tags. We envisage that our current technology would accelerate the use of miniaturized power sources for IoT applications, and inspire the development of intelligent manufacturing technology.