Owing to high natural abundance and relatively low redox potential of potassium (K), the K-ion battery (KIB) is a compelling substitute technology for the currently used lithium-ion battery (LIB). In this study, we propose a natural eco-friendly nitrogen (N)-doped porous carbon matrix from waste coffee grounds, which are abundantly available as biomass for KIB anode application. High electrical conduction and effective doping of active N atoms with lone electron pairs can be achieved through simple carbonization. Heteroatom N exists in multiple forms, such as graphitic N, pyridinic N, and pyrrolic N, all of which have lone pair electrons. The NC_coff-800 is optimized mesoporous structure with a good balance of graphitic N and coexistence of amorphous and graphitic carbon, allowing the highly reversible K storage properties to be preserved. To ensure practical utilization of NC_coff-800 as an anode, we assembled K-ion full-cells using a high-voltage Prussian blue/graphene (PB/G) composite as the cathode, which exhibited a high specific capacity of 90 mA h g⁻¹ at 0.1C and long-term cycling stability over 1000 cycles at 0.5C. This study suggests that an affordable, eco-friendly, high-performance practical KIB, providing excellent electrochemical properties, could be developed using an inexpensive anode derived from used coffee grounds together with a PB/G cathode.

中文翻译：

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一种源自可持续资源的掺氮非晶/石墨混合碳材料，用于低成本 K 离子电池阳极

由于钾（K）的高天然丰度和相对较低的氧化还原电位，钾离子电池（KIB）是目前使用的锂离子电池（LIB）的引人注目的替代技术。在这项研究中，我们提出了一种来自废咖啡渣的天然环保型氮 (N) 掺杂多孔碳基质，可作为生物质大量用于 KIB 阳极应用。通过简单的碳化可以实现具有孤电子对的活性N原子的高导电性和有效掺杂。杂原子N以多种形式存在，如石墨N、吡啶N和吡咯N，均具有孤对电子。NC_咖啡-800 是优化的介孔结构，具有良好的石墨氮平衡以及非晶碳和石墨碳共存，从而保留了高度可逆的储钾性能。为了确保 NC _coff -800 作为阳极的实际应用，我们使用高压普鲁士蓝/石墨烯 (PB/G) 复合材料作为阴极组装了 K 离子全电池，具有 90 mA hg 的高比容量^-1在 0.1C 和长期循环稳定性在 0.5C 下超过 1000 次循环。这项研究表明，可以使用从用过的咖啡渣中提取的廉价阳极和 PB/G 阴极来开发一种经济实惠、环保、高性能、实用的 KIB，它具有优异的电化学性能。