Abstract
Long-term stability is one of the most desired functionalities of energy storage microdevices for wearable electronics, wireless sensor networks and the upcoming Internet of Things. Although Li-ion microbatteries have become the dominant energy-storage technology for on-chip electronics, the extension of lifetime of these components remains a fundamental hurdle to overcome. Here, we develop an ultra-stable porous anode based on SnAu alloys able to withstand a high specific capacity exceeding 100 µAh cm−2 at 3 C rate for more than 6000 cycles of charge/discharge. Also, this new anode material exhibits low potential (0.2 V versus lithium) and one of the highest specific capacity ever reported at low C-rates (7.3 mAh cm−2 at 0.1 C). We show that the outstanding cyclability is the result of a combination of many factors, including limited volume expansion, as supported by density functional theory calculations. This finding opens new opportunities in design of long-lasting integrated energy storage for self-powered microsystems.
Highlights
With ultrahigh speed rate and low latency of 5 G mobile networks in the upcoming years, the emergence of the Internet of Things (IoT) is set to revolutionize all aspects of our lives[1,2]
We have reported 3D porous current collector based microbattery architecture for ultra-long life cycle (>6000 cycles) and extremely high areal capacity (>7 mAh cm−2) anodes
Explanations over origin of high stability and mechanism of charge storage are provided from materials/electrochemical characterizations and Density functional theory (DFT) simulations, opening a niche for further development of these 3D porous engineered architectures
Summary
With ultrahigh speed rate and low latency of 5 G mobile networks in the upcoming years, the emergence of the Internet of Things (IoT) is set to revolutionize all aspects of our lives[1,2]. The obtained porous alloy film (10–100 μm thick) is conductive, evolves into further nanoporous structure upon reaction with Li and exhibits remarkable mechanical stability upon lithiation, even using a standard liquid-based electrolyte, with limited volume expansion as established by DFT modelling This finding represents a major step forward towards the integration of high-energy long-cycling microbatteries for IoT applications. Similar electrodeposition process carried out on Au thin films prepared by physical vapor deposition (PVD) resulted in pure Sn phases rather than SnAu alloys (Supplementary Fig. 5). This is because for non-porous gold thin films, a limited amount of Au atoms is available for SnAu alloy formation by interaction with Sn2+ ions. Both from EDX and XRD analysis, we conclude to a conformal formation of SnAu alloy onto a porous framework
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