Li-CO₂ batteries are widely studied as a promising technology for greenhouse-gas CO₂ fixation as well as for energy conversion and storage devices. Their further development, however, is hindered by the refractory discharge products, leading to large polarization voltage and low round-trip efficiency. Here, W₂C nanoparticles embedded in the walls of carbon nanotubes (W₂C-CNTs) are prepared successfully. An efficient Li-CO₂ battery with a W₂C-CNTs cathode displays ultralow charge voltage (3.2 V) and high round-trip efficiency (90.1%). The low polarization comes from electron-rich W atoms that break the stable triangle of CO₃^2– via W–O bonds. The resulting amorphous discharge products could be readily and reversibly decomposed during charging. Raman and XAS spectra provide direct and solid evidence for the W–O bonds. Also, DFT calculations show there is electron transfer between the W₂C surface and Li₂CO₃, resulting in a low decomposition barrier for Li₂CO₃ on the W₂C substrate.

中文翻译：

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通过W-O键打破低极化Li-CO2电池的稳定碳酸盐三角形

Li-CO ₂电池作为温室气体CO ₂固定以及能量转换和存储设备的有前途的技术被广泛研究。然而，它们的进一步发展受到难熔放电产物的阻碍，导致极化电压大和往返效率低。在此，成功制备了嵌入碳纳米管壁中的W ₂ C 纳米粒子（W ₂ C-CNT）。具有 W ₂ C-CNTs 阴极的高效 Li-CO ₂电池显示出超低充电电压 (3.2 V) 和高往返效率 (90.1%)。低极化来自于打破 CO ₃ ^2–稳定三角形的富电子 W 原子通过 W-O 债券。所得的非晶放电产物在充电过程中很容易且可逆地分解。拉曼光谱和 XAS 光谱为 W-O 键提供了直接而可靠的证据。此外，DFT 计算表明 W ₂ C 表面和 Li ₂ CO ₃之间存在电子转移，导致W ₂ C 基材上的Li ₂ CO ₃分解势垒低。