Electrospraying preparation of metal germanate nanospheres for high-performance lithium-ion batteries and room-temperature gas sensors

Metal germanate nanospheres including Ca₂Ge₇O₁₆, Zn₂GeO₄ and SrGe₄O₉ were successfully synthesized by a direct and large-scale electrospraying method. As anodes for lithium ion batteries, the prepared metal germanate nanospheres showed high electrochemical lithium storage performance including excellent cycling stability and high rate capacity. Especially, the Ca₂Ge₇O₁₆ nanosphere anode delivered a high specific capacity of ∼ 670 mA h g^-1 at 0.2 A g^-1. The capacity retention was maintained around 71% even after 500 cycles. Moreover, when applied as room-temperature ammonia gas sensors, all three prepared germinate nanospheres showed significant sensing response values (6.04 for SrGe₄O₉, 2.73 for Zn₂GeO₄ and 1.70 for Ca₂Ge₇O₁₆), fast response-recovery time, excellent stability and outstanding selectivity.