氢氧化钾处理中间相炭微球应用于高倍率钾离子电池负极

KOH-treated mesocarbon microbeads used as high-rate anode materials for potassium-ion batteries

石墨具有成本低、放电稳定等优点,是钾离子电池极具发展前景的负极材料之一,但其倍率性能仍需改进。本文以中间相炭微球(MCMB)为原料,经KOH处理,设计了一种新型的石墨化负极。通过有限的氧化和轻微的嵌入,在MCMB表面形成了层间距增大的膨胀层,K+的扩散系数明显提高。作为负极时,改性MCMB在低于0.25 V下展现出高平台容量(271 mAh g^(-1)),优越的倍率性能(在1.0 A g^(-1)下,容量可达160 mAh g^(-1)),良好的循环稳定性(在0.1 A g^(-1)下循环100圈后,容量维持为184 mAh g^(-1));当采用羧甲基纤维素作为黏结剂时,KOH处理的MCMB具有高的首次库仑效率(79.2%)。本工作为设计具有优良储钾性能的石墨化材料提供了一种简便的策略。

Graphite is one of the most promising anode materials for potassium-ion batteries(PIBs)due to its low cost and stable discharge plateau.However,its poor rate performance still needs to be improved.A novel graphitic anode was designed from com-mercial mesocarbon microbeads(MCMBs)by KOH treatment.Using limited oxidation and slight intercalation,the interlayer spa-cing of graphitic layers on the surface of the MCMBs was increased,causing the K+diffusion rate to be significantly improved.When this modified material was combined with carboxymethyl cellulose as a binder(79.2%)and used as a PIB anode,it had a high plateau capacity below 0.25 V(271 mAh g^(−1)),superior rate capability(160 mAh g^(−1) at 1.0 A g^(−1)),excellent cycling stability(about 184 mAh g^(−1) after 100 cycles at 0.1 A g^(−1)),and a high initial coulombic efficiency.This work provides a simple strategy to prepare graphitic materials with an excellent potassium storage performance.