A sustainable society requires high-energy storage devices characterized by lightness, compactness, a long life and superior safety, surpassing current battery and supercapacitor technologies. Single-walled carbon nanotubes (SWCNTs), which typically exhibit great toughness, have emerged as promising candidates for innovative energy storage solutions. Here we produced SWCNT ropes wrapped in thermoplastic polyurethane elastomers, and demonstrated experimentally that a twisted rope composed of these SWCNTs possesses the remarkable ability to reversibly store nanomechanical energy. Notably, the gravimetric energy density of these twisted ropes reaches up to 2.1 MJ kg⁻¹, exceeding the energy storage capacity of mechanical steel springs by over four orders of magnitude and surpassing advanced lithium-ion batteries by a factor of three. In contrast to chemical and electrochemical energy carriers, the nanomechanical energy stored in a twisted SWCNT rope is safe even in hostile environments. This energy does not deplete over time and is accessible at temperatures ranging from −60 to +100 °C.

可持续发展的社会需要超越现有电池和超级电容器技术的轻质、紧凑、长寿命和卓越安全性的高能量存储设备。单壁碳纳米管（SWCNT）通常表现出很强的韧性，已成为创新能源存储解决方案的有希望的候选者。在这里，我们生产了包裹在热塑性聚氨酯弹性体中的单壁碳纳米管绳，并通过实验证明，由这些单壁碳纳米管组成的扭绳具有可逆存储纳米机械能的卓越能力。值得注意的是，这些绞绳的重量能量密度高达2.1 MJ kg ^-1，超过机械钢弹簧的储能能力四个数量级以上，超过先进锂离子电池的三倍。与化学和电化学能量载体相比，存储在扭曲的 SWCNT 绳中的纳米机械能量即使在恶劣的环境中也是安全的。这种能量不会随着时间的推移而耗尽，并且可以在 -60 至 +100 °C 的温度范围内获得。