Ma Liang, Li Xiaodan, Li Zhibin, Zhang Yajuan, Ji Zhong, Wang Hao, Mai Wenjie, Li Jinliang, Pan Likun
Siyuan Laboratory, Guangdong Provincial Engineering Technology Research Center of Vacuum Coating Technologies and New Materials, Department of Physics, Jinan University, Guangzhou, Guangdong 510632, China.
Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
J Colloid Interface Sci. 2021 Oct;599:857-862. doi: 10.1016/j.jcis.2021.04.140. Epub 2021 May 1.
In this work, we developed bismuth oxychloride anchoring on graphene nanosheets (BiOCl/G) composite via a simple one-step hydrothermal process for KIBs' anode, which delivers a high reversible specific capacity of 251 mAh g at 50 mA g after 50 cycles. Meanwhile, our BiOCl/G composite also exhibits a low voltage plateau during potassiation-depotassiation process, and such low voltage plateau in anode is helpful to improve the energy density of the full battery. In addition, we also provide the energy changes for migration of K-ion of our composite according to the density functional theory calculation and the result shows that the introduction of graphene in BiOCl can reduce the adsorption energy variation, which is in favor of K-ion intercalation process. In consideration of low potential plateau of our composite, we also introduce a new evaluation method, relative energy density (E), which not only includes the specific capacity, but also combines the potential plateau of the anode materials during potassiation-depotassiation process. According to the calculation, our BiOCl/G composite obtain an ultra-high E of 541 Wh kg at 50 mA g after 50 cycles with a relative energy conversion efficiency of 81%.
在这项工作中，我们通过一种简单的一步水热法制备了负载在石墨烯纳米片上的氯氧化铋（BiOCl/G）复合材料，用于钾离子电池的阳极。在50 mA g的电流密度下循环50次后，该复合材料展现出251 mAh g的高可逆比容量。同时，我们的BiOCl/G复合材料在钾化-脱钾过程中也表现出低电压平台，阳极中的这种低电压平台有助于提高全电池的能量密度。此外，根据密度泛函理论计算，我们还给出了复合材料中钾离子迁移的能量变化，结果表明在BiOCl中引入石墨烯可以降低吸附能变化，这有利于钾离子的嵌入过程。考虑到我们复合材料的低电位平台，我们还引入了一种新的评估方法——相对能量密度（E），它不仅包括比容量，还结合了阳极材料在钾化-脱钾过程中的电位平台。根据计算，我们的BiOCl/G复合材料在50 mA g的电流密度下循环50次后，获得了541 Wh kg的超高相对能量密度，相对能量转换效率为81%。
