Thermodynamic Analysis of Lithium Storage at Abrupt Junctions: Modeling and Experimental Evidence

Besides conventional lithium storage mechanisms, a novel interfacial storage mode was predicted to occur in M/LiX nanocomposites (M stands for any electron conductor, e.g. metal, which does not alloy with Li). According to this mechanism, the individual charges (Li⁺, e^-) are stored in the space charge layers, i.e., Li⁺ is accommodated at the Li₂O side of the boundary, while the e- is restricted to the metal side. As neither of the composites could store Li by itself, this is called ‘job-sharing’ mechanism [1]. Recently, a thermodynamic model for interfacial storage was developed, which describes both semi-infinite and mesoscopic boundary conditions [2]. In this contribution, we present that the predicted power law for the Li-activity dependence of the capacity for a semi-infinite model can be reproduced, in both Li₂O-Ru and LiF-Ni composites systems. Further exploitation of the interfacial storage mechanism may provide interesting information as to better compromise power and energy density for Li-ion batteries. Moreover, the correlations allow for a generalized storage picture of nanocrystals.

Reference:

[1] J. Jamnik and J. Maier, Phys. Chem. Chem. Phys., 5, 5215-5220 (2003).

[2] J. Maier, Angew. Chem. Int. Ed., 52(19), 4998-5026 (2013).