This result is because of the quantum confinement effect, which decreased the electrical conductivity and the sluggish charge and proton transfer.
The results presented here provide a new insight into the nanosize effect on the electrochemical performance to help design advanced energy storage devices.
Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China Correspondence: Professor X Yan, Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui road 18, Lanzhou, Gansu 730000, China.
It should be noted that the quantum confinement effect, a sort of nanosize effect, inevitably arises as the particle size reduces to the nanoscale, particularly when ), which are plotted in Figure 1 (additional details regarding this deduction are shown in Supplementary Information).
The widening of the band gap is closely related to the quantum confinement effect, which decreases Inspired by the above analyses, we hypothesize that minimizing the particle size may have a negative effect on the electrochemical performance, such that a critical size should exist for electrode materials.
In this context, theoretical analyses on the particle size, band gap and conductivity of nano-electrode materials were performed; it was determined that a critical size exist between particle size and electrochemical performance.
To verify this determination, for the first time, a scalable formation and disassociation of nickel-citrate complex approach was performed to synthesize ultra-small Ni(OH)nm.
In addition, while many nanomaterials used in electrochemical energy storage devices have been synthesized by various methods, a precisely size-controlled synthesis and a systematic study of size-dependent electrochemical performance for the electrode materials are rarely performed due to the difficulty in controlling the size, particularly when nm.
These reasons have strongly motivated us to explore size-controlled electrode materials to elucidate the nanosize effect on the electrochemical properties for sub-10-nm materials for energy storage applications.(a) Relationship between the conductivity and band gap shift for semiconductor materials from Equation (2).
(b) Relationship between the conductivity and the particle size of semiconductor materials.
Recently, electrochemical energy storage devices, such as batteries and supercapacitors, have attracted great attention because of their many advantages compared with other power-source technologies.
However, these devices could realize further gains in energy and power densities if the electrochemical performance of electrode materials is largely improved.