This paper aims to help fill a gap in the literature on Li-ion battery electrode materials due to the absence of measured elastic constants needed for diffusion induced stress models. By examining results from new first principles density functional theory (DFT) calculations of LiCoO 2 , LiMn 2 O 4 , (and their delithiated hosts, CoO 2 and MnO 2 ), Li x Al alloys, and data from the extant literature on LiFePO 4 (and FePO 4 ), LiTi 2 O 4 (and Li 2 Ti 2 O 4 ), Li x Si, Li x Sn and lihtium graphite-interaction-compounds, a compelling picture emerges on the dependency of the elastic properties on Li concentration. Specifically, three distinct categories of behavior are found: (a) the averaged Young's moduli change very minimally upon lithiation of the spinel and olivine structures; (b) lithiation induced stiffening is observed only when new and stronger bonds between the Li ions and the host materials are formed in layered compounds; and (c) for alloy-forming electrode materials, such as Si, β-Sn and Al, the averaged Young's moduli of lithiated compounds follow the linear rule of mixtures. The tendency of ductile or brittle behavior electrode materials is investigated with the Pugh criterion, and a ductile to brittle transition was found to occur during lithiation of Al and β-Sn, but not in Si. One of the critical challenges in advanced lithium-ion (Li-ion) batteries is preventing fracture and mechanical failure of electrodes during lithium insertion and de-insertion. Most Li-ion battery electrodes experience volume changes associated with Li concentration changes within the host particles during charging and discharging.1 Graphite, for example, is the most common negative electrode for Li-ion batteries. Its volume increases by as much as 10% when Li intercalates between the sheets of C atoms.2 Compared to graphite, Si can store ∼10 times more Li, but it undergoes a massive volume expansion of the order of 300%.3 The large volume expansion, phase transition, and the associated Li diffusion-induced stresses (DIS) within electrode materials can lead to their fracture and failure which results in battery capacity loss and power fade.Significant progress toward understanding how DIS can be minimized to increase mechanical durability of Li-ion batteries 4-13 has been made. For example, Verbrugge and Cheng 11 modeled the evolution of stress and strain energy within a spherically-shaped electrode particle under either galvanostatic or potentiostatic operation. They also investigated the effects of surface energy and surface elasticity on the stress evolution in spherical electrodes.10 Wolfenstine 14 demonstrated that using Young's modulus, fracture toughness, and volume change, a critical particle size needed to lower capacity fade could be estimated with an analytical model. Recent models have been more material specific. Woodford et al. 15 further derived a failure criterion for crack propagation in individual Li x Mn 2 O 4 electrode particles during galvanostatic charging based on fracture mechanics. Using a combination...
