TY - JOUR
T1 - Diffusion kinetics governing the diffusivity and diffusion anisotropy of alloying anodes in Na-ion batteries
AU - Park, Jun Hyoung
AU - Choi, Yong Seok
AU - Byeon, Young Woon
AU - Ahn, Jae Pyoung
AU - Lee, Jae Chul
N1 - Funding Information:
This work was supported by the Samsung Research Funding Center of Samsung Electronics under project No. SRFC-MA1602-04 and the National Research Foundation of Korea (NRF) grant funded by the Korea government ( MEST , NRF-2018R1A2B6003927 ).
PY - 2019/11
Y1 - 2019/11
N2 - Diffusion in alloying anode materials was previously viewed as solute diffusion in conventional alloys. However, solute diffusion, neglecting the presence of a thin intermediate reaction layer between the unreacted anode material and inflowing carrier ions, is insufficient to account for the diffusion kinetics in alloying anodes and their influence on the electrochemical properties of batteries. Here, by performing a comparative study on Na-Sb and Na-Sn battery systems displaying differing diffusion kinetics, we establish the relationship between diffusion kinetics and electrochemical properties for batteries. In situ microelectrochemical experiments show that sodiation in Na-Sb and Na-Sn systems is governed by an interface-controlled reaction (ICR) and a diffusion-controlled reaction (DCR), respectively, causing them to display significantly different diffusion rates, diffusion anisotropy, and possibly self-limiting diffusion of carrier ions. Density functional theory calculations are performed to elucidate the structural origin of the observed diffusion behaviors. It is found that the different degrees of structural stability evaluated for the propagating interfaces of the two systems are responsible for the differing diffusion kinetics, which in turn determine the respective diffusion rates and diffusion anisotropy of the anode materials. The present study provides crude yet quantitative guidelines for selecting battery materials and can be used to develop fast-charging batteries with high stability and improved cycle life.
AB - Diffusion in alloying anode materials was previously viewed as solute diffusion in conventional alloys. However, solute diffusion, neglecting the presence of a thin intermediate reaction layer between the unreacted anode material and inflowing carrier ions, is insufficient to account for the diffusion kinetics in alloying anodes and their influence on the electrochemical properties of batteries. Here, by performing a comparative study on Na-Sb and Na-Sn battery systems displaying differing diffusion kinetics, we establish the relationship between diffusion kinetics and electrochemical properties for batteries. In situ microelectrochemical experiments show that sodiation in Na-Sb and Na-Sn systems is governed by an interface-controlled reaction (ICR) and a diffusion-controlled reaction (DCR), respectively, causing them to display significantly different diffusion rates, diffusion anisotropy, and possibly self-limiting diffusion of carrier ions. Density functional theory calculations are performed to elucidate the structural origin of the observed diffusion behaviors. It is found that the different degrees of structural stability evaluated for the propagating interfaces of the two systems are responsible for the differing diffusion kinetics, which in turn determine the respective diffusion rates and diffusion anisotropy of the anode materials. The present study provides crude yet quantitative guidelines for selecting battery materials and can be used to develop fast-charging batteries with high stability and improved cycle life.
KW - Density functional theory calculations
KW - Diffusion kinetics
KW - Diffusion-controlled reaction
KW - In situ sodiation experiment
KW - Interface-controlled reaction
KW - Sodium-ion battery
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U2 - 10.1016/j.nanoen.2019.104041
DO - 10.1016/j.nanoen.2019.104041
M3 - Article
AN - SCOPUS:85070987560
VL - 65
JO - Nano Energy
JF - Nano Energy
SN - 2211-2855
M1 - 104041
ER -