【作者】 张杰；

【导师】 孟庆函；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2021， 硕士

【摘要】 当今世界,由于化石能源(石油、煤等)的快速消耗和严重的环境污染问题,对高性能储能设备的需求急剧增长。石墨烯气凝胶(GA)有着出色的电化学性能,是电极材料的理想候选者。并且由于氧化石墨烯(GO)表面有着丰富的官能团,可以和其它材料进行复合来进一步提升其电化学性能。本文采用水热法成功制备了亲水炭黑/混杂多孔石墨烯气凝胶,使得亲水炭黑呈串状或球状分布在石墨烯片层之上。这种结构不仅可以减少石墨烯片层的坍塌,还可以提供快速的离子扩散路径,使得更多石墨烯片层的边缘部位参与双电层电容。接着在亲水炭黑/混杂多孔石墨烯气凝胶最佳比例的基础上负载层状双氢氧化物(LDH),最后将这些材料在超级电容器和电吸附脱盐方面做了系统的研究。研究内容如下:1、采用改进hummers法制备GO,并利用过氧化氢的刻蚀作用在GO片层上造孔来制备多孔氧化石墨烯(HGO),然后将HGO与GO按照不同质量比例混合,通过水热法成功制备了混杂多孔石墨烯气凝胶(HGA-n)。电化学研究发现当HGO:GO=6:4时(HGA-3)电化学性能最好。在0.1 A g-1的电流密度下,HGA-3的比电容高达379F g-1,与GA相比提高大约89%。然后在HGA-3的基础上掺杂亲水炭黑,当亲水炭黑和(HGO+GO)的质量比为1:4时(HGAC-2)电化学性能最佳。在0.1 A g-1的电流密度下,HGAC-2的比电容达到438 F g-1,相较于HGA-3提高了大约13%。并且,在10 A g-1的电流密度下,HGAC-2经过5000次循环后的比电容保留率高达92.6%。在电吸附测试中,HGAC-2在1.2 V电压和初始NaCl浓度为800 mg L-1的条件下最大电吸附容量为49.85 mg g-1,比HGA-3 电极(43.04mgg-1)提高大约 16%。并且 HGAC-2 在 NaCl浓度为1600 mg L-1时的最大吸附速率为2.69 mg g-1 s-1,比HGA-3(1.61 mgg-1s-1)提高大约67%。2、以亲水炭黑/混杂多孔石墨气凝胶为基体,采用水热法成功制备了NiCo-LDH/混杂多孔石墨烯气凝胶复合材料(NiCo-LDH-n)。结构表征发现NiCo-LDH-1和NiCo-LDH-2复合材料具有石墨烯片层上长花的复合结构。经过电化学测试发现NiCo-LDH-2具有最佳的电化学性能。在扫速为 1.0 mV s-1 时,NiCo-LDH-2 有着 747 F g-1 的高比电容,与 NiCo-LDH(608 F g-1)和HGAC-2(461 F g-1)相比分别提升约23%和62%。另外,NiCo-LDH-2在10 Ag-1的电流密度下,经过5000次循环其比电容损失仅8.7%。在电吸附测试中,NiCo-LDH-2在1.2 V电压和初始NaCl浓度为800 mg L-1的条件下达到平衡时的电吸附容量为61.99 mg g-1,比NiCo-LDH(18.09 mg g-1)提高近2.43倍,并且其最大吸附速率为38.68 mgg-1 min-1。更多还原

【Abstract】 Nowadays,due to the fast consumption of fossil fuels(oil,coal,etc.)and tremendous serious environmental issues,the demand for high performance energy-storage devices has been increasing dramatically.Graphene aerogel(GA)is identified as an ideal electrode material due to its excellent electrochemical performance.Moreover,since graphene oxide(GO)has many functional groups,it can be combined with other materials to further improve its electrochemical performance.In this paper,hydrophilic carbon black/hybrid holey graphene aerogels have been successfully prepared by hydrothermal method.The hydrophilic carbon black is distributed on the graphene sheets in a string or spherical shape.Such structure can not only prevent the compact restack of graphene sheets,but also provide rapid diffusion path for more edge plane participation in doublelayer capacitance.Next,the layered double hydroxide(LDH)is loaded on the optimal ratio of hydrophilic carbon black/hybrid holey graphene aerogels.Finally,systematic research is done on these materials in supercapacitor and capacitive deionization.The research contents are as follows:1.GO is prepared by improved hummers method,and the holey graphene oxide(HGO)is synthesized by etching with hydrogen peroxide.Then HGO is mixed with GO in different mass ratios to prepare hybrid holey graphene aerogel(HGA-n)by hydrothermal method.Electrochemical studies exhibit that HGA-3(the mass ratio of HGO to GO is 6:4)has the highest specific capacitance of 379 F g-1 at a current density of 0.1 A g-1.Compared with GA,the specific capacitance is improved by about 89%.Then,hydrophilic carbon black is loaded on HGA-3.HGAC-2(the mass ratio of(HGO+GO)to hydrophilic carbon black is 4)displays the highest specific capacitance of 438 F g-1 at a current density of 0.1 A g-1,which is about 13%higher than HGA-3.In addition,the specific capacity retention of HGAC-2 is about 92.6%after 5000 cycles at a current density of 10 A g-1.As the electrode material for capacitive deionization,the salt adsorption capacity of HGAC-2 is 49.85 mg g1 under the conditions of 1.2 V and an initial concentration of 800 mg L-1 NaCl solution,which is about 16%higher than HGA-3 electrode(43.04 mg g-1).Moreover,the maximum ion removal rate of HGAC-2 is 2.69 mg g-1 s-1 as the NaCl concentration is 1600 mg L-1,which is about 67%higher than HGA-3(1.61 mg g-1 s-1).2.The NiCo-LDH/hybrid holey graphene aerogel composites(NiCoLDH-n)are successfully prepared using the hydrophilic carbon black/hybrid holey graphene aerogel as the matrix by hydrothermal method.The structure characterization exhibits that NiCo-LDH-1 and NiCo-LDH-2 have a composite structure with flowers on the graphene sheets.Electrochemical tests exhibit that NiCo-LDH-2 has the best electrochemical performance.At a scan rate of 1.0 mV s-1,the specific capacitance of NiCo-LDH-2 can reach 747 F g-1,which is 23%and 62%higher than NiCo-LDH(608 F g-1)and HGAC-2(461 F g-1),respectively.In addition,the specific capacity of NiCo-LDH-2 decreases by only 8.7%after 5000 cycles at a current density of 10 A g-1.In the capacitive deionization test,the NiCo-LDH-2 displays a salt adsorption capacity of 61.99 mg g-1 under the conditions of 1.2 V and an initial concentration of 800 mg L-1 NaCl solution,which is about 2.43 times higher than NiCo-LDH(18.09 mg g1).Moreover,the maximum ion removal rate of NiCo-LDH-2 is 38.68 mg g-1 min-1.更多还原