Graphene(G),as a typical two-dimensional material,is often used as an additive for liquid lubricants.However,graphene is mostly added to liquid lubricants in a one-time manner in friction;it mainly exists in the form ...Graphene(G),as a typical two-dimensional material,is often used as an additive for liquid lubricants.However,graphene is mostly added to liquid lubricants in a one-time manner in friction;it mainly exists in the form of multilayer agglomerated structures due to theπ–πstacking between graphene sheets,making it unable to fully exert the synergistic lubrication function.Herein,we propose a new macroscopic superlubric system of graphene/potassium hydroxide(G/KOH)solution;and the graphene additive involved is exfoliated in-situ from graphene/epoxy(G/EP)friction pair by friction,continuously providing freshly-peeled graphene into KOH solution and minimizing the adverse effects of graphene agglomeration.Moreover,the in-situ produced graphene additive has thinner thickness and better anti-aggregation ability,which provide more graphene to accommodate OH−,form more stacked sandwich structures of OH−/graphene/OH−between friction pairs(i.e.,equivalent to a moving pulley block with more wheels),and finally realize superlubricity.This study develops a new liquid superlubric system suitable for alkaline environments,and at the same time proposes a new way to gradually release graphene additives in situ,rather than adding them all at once,deepening the understanding to liquid superlubricity mechanism,and paving the experimental foundation for the practical application of macroscopic superlubricity.展开更多
基金supported by the National Natural Science Foundation of China(21975109 and 52075224)China Postdoctoral Science Foundation(2019M651718)the Natural Science Foundation of Jiangsu Province(BK20201423)。
文摘紧凑型超级电容器需要具有高体积能量和功率密度的高密度碳.然而,大多数传统的密度提升方案都是基于孔隙压缩,导致提高体积性能的同时过多地牺牲倍率性能.在此,本研究从碳单元有序堆叠的相反角度出发,提出了一种通过调节模板形貌在纳米和微米双尺度上压缩碳单元之间剩余孔隙的新策略(即一级碳纳米笼和二级由碳纳米笼组成的类碟状组装体的双尺寸排序).优化的纳微有序碳单元的电极密度高达1.08 g cm^(-3)(是商业活性炭的两倍);在离子液体中表现了创纪录的体积能量密度(79 Wh L^(-1))和功率容量(31 kW L^(-1)),以及出色的稳定性(>30,000次循环)和理想的库仑效率(~100%).即使在商业级电极厚度下,其可用的最大堆叠功率密度仍然高达12 kW L^(-1),远高于大多数报道的致密碳.如此出色的体积性能使其在同时需要高体积能量和功率密度的领域具有巨大潜力.
基金supported by the National Natural Science Foundation of China(52075224,21975109,51975252,and 52075225)Natural Science Foundation of Jiangsu Province(BK20201423)+1 种基金Foundation of State Key Laboratory of Solid Lubrication(LSL-1801)Tribology Science Fund of State Key Laboratory of Tribology(SKLTKF18B03).
文摘Graphene(G),as a typical two-dimensional material,is often used as an additive for liquid lubricants.However,graphene is mostly added to liquid lubricants in a one-time manner in friction;it mainly exists in the form of multilayer agglomerated structures due to theπ–πstacking between graphene sheets,making it unable to fully exert the synergistic lubrication function.Herein,we propose a new macroscopic superlubric system of graphene/potassium hydroxide(G/KOH)solution;and the graphene additive involved is exfoliated in-situ from graphene/epoxy(G/EP)friction pair by friction,continuously providing freshly-peeled graphene into KOH solution and minimizing the adverse effects of graphene agglomeration.Moreover,the in-situ produced graphene additive has thinner thickness and better anti-aggregation ability,which provide more graphene to accommodate OH−,form more stacked sandwich structures of OH−/graphene/OH−between friction pairs(i.e.,equivalent to a moving pulley block with more wheels),and finally realize superlubricity.This study develops a new liquid superlubric system suitable for alkaline environments,and at the same time proposes a new way to gradually release graphene additives in situ,rather than adding them all at once,deepening the understanding to liquid superlubricity mechanism,and paving the experimental foundation for the practical application of macroscopic superlubricity.
