Nanofullerene regulated electric field to achieve stable Sn metal anode for aqueous Sn batteries

Metallic Tin (Sn) is an attractive anode material for aqueous batteries due to its high theoretical capacity, low redox potential and strong corrosion resistance. However, the uneven deposition of Sn and severe interfacial side reactions limit its wide application. Herein, a nanoscale fullerene (C₆₀) coating on a Sn anode has been developed by the physical evaporation deposition technology to eliminate complicated side reactions. This coating improves the homogeneity of the Sn anode surface electric field, and reduces the formation of "dead tin". As a result, the C₆₀-coated Sn anode can maintain a low voltage hysteresis cycle for more than 850 h. The aqueous NiO//Sn cell encapsulated by this anode achieves a maximum specific discharge capacity of 79.3 mAh·g⁻¹ at a current density of 1.5 A·g⁻¹. Moreover, as a proof of concept, we propose an aqueous electrochromic Sn battery, which can realize energy storage and reversibly color switch, yielding favorable optical modulation of about 61.1% at 523 nm. This work has developed a cost-effective and high-reliability interfacial engineering strategy that boosts practical uses of Sn metal electrodes, as well as promotes the application of innovative aqueous rechargeable batteries with electrochromic properties.

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