Volumetric energy density is a universal and the most important standardized figure-of-merit to quantify energy technologies, regardless of the operating mechanism, form of energy, energy scale, etc. In terms of triboelectric nanogenerators (TENGs), considering their cycle-by-cycle operation mechanism, output energy density has been demonstrated as the key factor limiting the output performance. However, the state-of-the-art output energy density of TENGs in the ambient environment is only <10⁴ J m⁻³, as limited by two crucial factors: charge density and breakdown threshold voltage. In this work, we proposed a comprehensive strategy including charge excitation, interface insulation, and material screening to boost the maximized output energy density of the TENGs. In particular, charge excitation was effectively realized by an external high-voltage (HV) source, while interface insulation was achieved through liquid oils to alleviate the electric field and suppress the breakdown effect. Moreover, a set of comprehensive parameters involving triboelectrification, dielectric properties, leakage properties, etc. are fully investigated for screening triboelectric materials. With that, we experimentally achieved a record-high charge density of 2.3 mC m⁻² among SFT-TENGs and yielded the maximum output energy density of 4.3 × 10⁵ J m⁻³, as a new record in the field. A theoretical maximum energy density of 1.1 × 10⁶ J m⁻³ is predicted as simulated by the finite-element method. This work demonstrates the boosted capability of TENGs' maximized output energy density from both theoretical and experimental perspectives, which will be an important step towards designing high-performance TENGs for efficient energy harvesting with broad application scope.

中文翻译：

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提高摩擦纳米发电机的最大输出能量密度


体积能量密度是量化能源技术的通用且最重要的标准化品质因数，无论其运行机制、能源形式、能源规模等如何。对于摩擦纳米发电机（TENG）而言，考虑到其循环周期-循环运行机制，输出能量密度已被证明是限制输出性能的关键因素。然而，TENG 在周围环境中的最先进输出能量密度仅为 <10 ⁴ J m ⁻³ ，受到两个关键因素的限制：电荷密度和击穿阈值电压。在这项工作中，我们提出了一种综合策略，包括电荷激发、界面绝缘和材料筛选，以提高 TENG 的最大输出能量密度。特别是，通过外部高压（HV）源有效实现电荷激发，同时通过液体油实现界面绝缘，以减轻电场并抑制击穿效应。此外，还充分研究了一组涉及摩擦起电、介电性能、漏电性能等综合参数，用于筛选摩擦起电材料。由此，我们在 SFT-TENG 中实验性地实现了 2.3 mC m ⁻² 的创纪录高电荷密度，并产生了 4.3 × 10 ⁵ J m ⁻³ ，作为该字段中的新记录。通过有限元方法模拟，预测理论最大能量密度为 1.1 × 10 ⁶ J m ⁻³ 。 这项工作从理论和实验的角度证明了TENG最大化输出能量密度的能力，这将是设计高性能TENG以实现广泛应用范围的高效能量收集的重要一步。