合理设计空心V_(2)O_(3)/C集成电极赋予水系超级电容器2.4V电压窗口

Enabling 2.4-V aqueous supercapacitors through the rational design of an integrated electrode of hollow vanadium trioxide/carbon nanospheres

水系超级电容器具有能量密度高,循环稳定性好,安全性高等优势,但低能量密度阻碍了其进一步应用.通过一种简单有效的方法得到具有高能量密度和宽电压的水系超级电容器依旧面临挑战.本工作设计了一种三氧化二钒/碳纳米空心球(H-V_(2)O_(3)/C)电极,并将其应用于水系超级电容器.碳的引入可以提高材料的导电性和稳定性,同时空心结构有利于提高电化学活性面积,提供快速的离子传输通道.此外,这种集成电极可同时工作于正极和负极电压窗口.因此,H-V_(2)O_(3)/C集成电极在-1.1–1.3 V的电压窗口下具有708.6 F g^(-1)的比容量.基于其多重储能机制,得到的水系对称超级电容器比传统的(非)对称超级电容器具有更高的电压窗口和能量密度.在2.4 V的宽电压下工作,当功率密度为1204.6 W kg^(-1)时具有96.8 W h kg^(-1)的高能量密度,同时具有优良的循环稳定性.本研究对电极材料的设计和制备具有一定的启发意义,为开发宽电压水系超级电容器开辟了一条新途径.

Aqueous supercapacitors(SCs)exhibit several advantages,including high-power density,cycling durability,and safety;however,the shortage of low energy density inhibits their further application.Acquiring an excellent performance upon using simple strategies would be beneficial,but remains challenging.Here,an integrated electrode of hollow V_(2)O_(3)/carbon nanospheres(H-V_(2)O_(3)/C)was designed and synthesized for SCs.The introduction of carbon can increase the conductivity and stability,whereas the hollow structure endows H-V_(2)O_(3)/C with a high specific surface area and rapid transport of ions.Moreover,the H-V_(2)O_(3)/C integrated electrode can simultaneously work in both negative and positive potential windows.Benefiting from these advantages,the H-V_(2)O_(3)/C integrated electrode exhibits a specific capacitance as high as 708.6 F g^(-1) in a wide voltage window of-1.1-1.3 V.Furthermore,stemming from the multiple energy storage mechanisms,the aqueous integrated full SC device exhibits a wider potential window and higher energy density than the traditional(a)symmetric ones.Therefore,the proposed device delivers a wide voltage window of 2.4 V with an energy density of 96.8 W h kg^(-1) at a power density of 1204.6 W kg^(-1),as well as superior cycling stability.This study enlightens the design and preparation of electrode materials,opening up a possible approach for developing wide-voltage aqueous SCs.