A chemically bonded NaTi2( PO4)3/rGO microsphere composite as a high-rate insertion anode for sodium-ion capacitors
A chemically bonded NaTi2( PO4)3/rGO microsphere composite as a high-rate insertion anode for sodium-ion capacitors
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DOI：
10.1039/c7ta05252a
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发表时间：
2017-09-07
影响因子：
11.9
通讯作者：
Kim, Kwang-Bum
中科院分区：
文献类型：
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作者：
Roh, Ha-Kyung;Kim, Myeong-Seong;Kim, Kwang-Bum
我们报道了一种高速率的NaTi2(PO4)(3)/石墨烯复合材料的合成，用作高功率钠离子混合电容器的阳极材料，具有以下特性：(1)将NaTi2(PO4)(3)的粒径缩小到纳米尺度，以减少Na+离子的扩散长度；(2)NaTi2(PO4)(3)纳米颗粒与石墨烯之间的化学键合，以提高导电性；(3)相互连接的纳米孔结构，使Na+离子容易接近NaTi2(PO4)(3)。为此，采用氧化石墨烯、NaH2PO4中心点2H(2)O、Ti(OC2H5)(4)和NH4H2(PO4)(3)的混合溶液，通过喷雾干燥法制备了NaTi2(PO4)(3)/rGO微球复合材料，其中钛的所有组分均以离子形态存在，以促进复合材料中NaTi2(PO4)(3)与rGO之间的化学结合。NaTi2(PO4)(3)/rGO微球复合材料在NaTi2(PO4)(3)纳米颗粒（< 80 nm）与rGO之间形成了TiO-C键，并具有相互连接的纳米孔结构。NaTi2(PO4)(3)/rGO微球复合材料在0.1℃倍率下的比容量为133 mA h g(-1)，具有优异的倍率性能（在50℃倍率下保持70%的容量）和非常稳定的循环性能（在高10C倍率下循环200次后仅损失2%的容量）。此外，用NaTi2(PO4)(3)/rGO阳极和交流阴极组装的NHC的能量密度和功率密度远优于其他金属氧化物基阳极和交流阴极组装的NHC。
We report on the synthesis of a high rate NaTi2(PO4)(3)/graphene composite for use as an anode material for high power Na-ion hybrid capacitors with the following characteristics; (1) reduction of the particle size of NaTi2(PO4)(3) to the nanometer scale in order to reduce the Na+ ion diffusion length, (2) chemical bonding between NaTi2(PO4)(3) nanoparticles and graphene in order to improve electrical conductivity, and (3) interconnected nanoporous structures in order to allow easy access of Na+ ions to NaTi2(PO4)(3). For this, the NaTi2(PO4)(3)/rGO microsphere composite was prepared via a facile spray drying method using a solution mixture of graphene oxide, NaH2PO4 center dot 2H(2)O, Ti(OC2H5)(4) and NH4H2(PO4)(3), in which all the components of the titanium were present as ionic species in order to facilitate the chemical bonding between NaTi2(PO4)(3) and rGO in the composite. The NaTi2(PO4)(3)/rGO microsphere composite had a TiO-C bond between NaTi2(PO4)(3) nanoparticles (< 80 nm) and rGO and interconnected nanoporous structures. The NaTi2(PO4)(3)/rGO microsphere composite exhibited a near theoretical specific capacity of 133 mA h g(-1) at a 0.1 C-rate and excellent rate capability (70% capacity retention at a 50 C-rate) with very stable cycling performance (only 2% capacity loss after 200 cycles at a high rate of 10C). Furthermore, the energy density and power density of the NHC assembled with a NaTi2(PO4)(3)/rGO anode and an AC-based cathode are far better than those of other NHCs assembled using other metal oxide-based anodes and AC cathodes.