Supercapacitors have aroused considerable attention due to their high power capability, which enables charge storage/output in minutes or even seconds. However, to achieve a high energy density in a supercapacitor has been a long‐standing challenge. Here, graphite is reported as a high‐energy alternative to the frequently used activated carbon (AC) cathode for supercapacitor application due to its unique Faradaic pseudocapacitive anion intercalation behavior. The graphite cathode manifests both higher gravimetric and volumetric energy density (498 Wh kg⁻¹ and 431.2 Wh l⁻¹) than an AC cathode (234 Wh kg⁻¹ and 83.5 Wh l⁻¹) with peak power densities of 43.6 kW kg⁻¹ and 37.75 kW l⁻¹. A new type of Li‐ion pseudocapacitor (LIpC) is thus proposed and demonstrated with graphite as cathode and prelithiated graphite or Li₄Ti₅O₁₂ (LTO) as anode. The resultant graphite–graphite LIpCs deliver high energy densities of 167–233 Wh kg⁻¹ at power densities of 0.22–21.0 kW kg⁻¹ (based on active mass in both electrodes), much higher than 20–146 Wh kg⁻¹ of AC‐derived Li‐ion capacitors and 23–67 Wh kg⁻¹ of state‐of‐the‐art metal oxide pseudocapacitors. Excellent rate capability and cycling stability are further demonstrated for LTO‐graphite LIpCs.

中文翻译：

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活性炭之外：具有高能量和高功率密度的石墨-阴极衍生的锂离子伪电容器

超级电容器由于其高功率能力而引起了相当大的关注，这使得电荷可以在几分钟甚至几秒钟内存储/输出。然而，在超级电容器中实现高能量密度是一项长期的挑战。在这里，据报道石墨因其独特的法拉第伪电容性阴离子嵌入行为而可替代超级电容器应用中常用的活性炭（AC）阴极的高能替代品。石墨阴极清单都更高的重量和体积能量密度（瓦498千克^-1和431.2瓦升^-1）比AC阴极（234瓦时千克^-1和83.5瓦升^-1），用43.6千瓦公斤的峰值功率密度^{- 1}和37.75 kW l ^-1。因此提出了一种新型的锂离子假电容器（LIpC），并以石墨为阴极，预镀石墨或Li ₄ Ti ₅ O ₁₂（LTO）为阳极进行了演示。将所得的石墨-石墨LIpCs递送167-233瓦时公斤的高能量密度^-1在0.22-21.0千瓦公斤功率密度^-1（基于活性物质在两个电极），比20-146瓦千克高得多^-1的源自交流的锂离子电容器和23–67 Wh kg ^-1的最新金属氧化物伪电容器。LTO石墨LIpC的优异速率能力和循环稳定性得到进一步证明。