Journal Article Concentration dependence of Li+/Na+ diffusion in manganese hexacyanoferrates

Takachi, Masamitsu  ,  Fukuzumi, Yuya  ,  Moritomo, Yutaka

55 ( 6 )  , p.067101 , 2016-06 , The Japan Society of Applied Physics
Manganese hexacyanoferrates (Mn-HCFs) with a jungle-gym-type structure are promising cathode materials for Li+/Na+ secondary batteries (LIBs/SIBs). Here, we investigated the diffusion constants D Li/D Na of Li+/Na+ against the Li+/Na+ concentration x Na/x Li and temperature (T) of A 1.32Mn[Fe(CN)6]0.833.6H2O (A = Li and Na). We evaluated the activation energy $E_{\text{a}}^{\text{Li}}/E_{\text{a}}^{\text{Na}}$ of D Li/D Na against x Na/x Li. We found that $E_{\text{a}}^{\text{Na}}$ steeply increases with x Na from 0.41 eV at x Na = 0.69 to 0.7 eV at 1.1. The increase in $E_{\text{a}}^{\text{Na}}$ is ascribed to the occupancy effect of the Na+ site. The increase in $E_{\text{a}}^{\text{Li}}$ is suppressed, probably because the number of Li+ sites is three times that of Na+ sites.

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