High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance
High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance
复制标题
DOI：
10.1038/nmat3601
复制
发表时间：
2013-06-01
期刊：
影响因子：
41.2
通讯作者：
Dunn, Bruce
中科院分区：
文献类型：
--
作者：
Augustyn, Veronica;Come, Jeremy;Dunn, Bruce
赝电容通常与表面或近表面可逆氧化还原反应有关，如在酸性电解质中用RuO 2中心点xH（2）O观察到的。然而，我们最近证明，赝电容机制发生时，锂离子插入到介孔和斜方晶Nb 2 O 5（T-Nb 2 O 5;参考文献1，2）的介孔膜。在这里，我们量化的T-Nb 2 O 5中的电荷存储的动力学：电流随时间呈反比，电荷存储容量，这是主要独立的速率，氧化还原峰，即使在高速率下表现出小的电压偏移。我们还定义了这个过程所需的结构特征，称为嵌入伪电容，这是一个晶体网络，提供二维传输途径，并且嵌入时结构变化很小。从嵌入赝电容实现的主要益处是在短时间内实现高水平的电荷存储，因为不存在来自固态扩散的限制。用T-Nb_2 O_5制备的厚电极（厚度达40 μ m）提供了利用嵌入赝电容获得高速率电荷存储器件的希望。
Pseudocapacitance is commonly associated with surface or near-surface reversible redox reactions, as observed with RuO2 center dot xH(2)O in an acidic electrolyte. However, we recently demonstrated that a pseudocapacitive mechanism occurs when lithium ions are inserted into mesoporous and nanocrystal films of orthorhombic Nb2O5 (T-Nb2O5; refs 1,2). Here, we quantify the kinetics of charge storage in T-Nb2O5: currents that vary inversely with time, charge-storage capacity that is mostly independent of rate, and redox peaks that exhibit small voltage offsets even at high rates. We also define the structural characteristics necessary for this process, termed intercalation pseudocapacitance, which are a crystalline network that offers two-dimensional transport pathways and little structural change on intercalation. The principal benefit realized from intercalation pseudocapacitance is that high levels of charge storage are achieved within short periods of time because there are no limitations from solid-state diffusion. Thick electrodes (up to 40 mu m thick) prepared with T-Nb2O5 offer the promise of exploiting intercalation pseudocapacitance to obtain high-rate charge-storage devices.