This study presents a negatively charged hydrochar from Aesculus indica waste, employing a microwave-assisted hydrothermal carbonization (HTC) method at very low temperatures (120∼200 °C). The research shows the utilization of these negatively-charged-oxygen-containing hydrochars in lithium-sulfur (Li-S) batteries effectively mitigates polysulfide shuttling through electrostatic repulsive forces and simultaneously facilitate uniform lithium-ion transportation, leading to substantial improvement in battery performance. Through detailed investigations into the HTC reaction mechanism, the concentration of the negatively charged oxygen functional groups is tunable by controlling the carbonization process, which could further improve the enhancement effects. Furthermore, negatively-charged-oxygen-containing hydrochars were utilized as modified separator in Li-S batteries to enhance the electrochemical performance. The batteries assembled with hydrochar modified separator, has an initial discharge capacity of 1216 mAh g at 0.1 C, and after 200 cycles at 1 C, its reversible discharge capacity was still 800 mAh g with more than 80 % capacity retention. This research not only provides an efficient method for the utilization of waste biomass, but also offers a new approach for the preparation of negatively charged carbon for lithium-sulfur batteries.

中文翻译：

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来自七叶树废料的带负电的水炭：一种增强锂硫电池性能的可持续材料


本研究提出了一种从七叶树废物中提取的带负电的水炭，采用微波辅助水热碳化（HTC）方法在极低的温度（120∼200°C）下进行。研究表明，在锂硫（Li-S）电池中使用这些带负电的含氧氢炭可有效减轻多硫化物通过静电斥力的穿梭，同时促进均匀的锂离子传输，从而显着提高电池性能。通过对HTC反应机理的详细研究，通过控制碳化过程可以调节带负电的氧官能团的浓度，从而可以进一步提高增强效果。此外，带负电的含氧氢炭被用作锂硫电池中的改性隔膜，以提高电化学性能。采用氢炭改性隔膜组装而成的电池，在0.1 C下首次放电容量为1216 mAh g，在1 C下循环200次后，可逆放电容量仍为800 mAh g，容量保持率超过80%。该研究不仅为废弃生物质的利用提供了一种有效的方法，也为锂硫电池负电碳的制备提供了一种新途径。