Influence of Mechanical Strain on the Electrochemical Lithiation of Aluminum-Based Electrode Materials

While an Al-Li alloy is expected to be useful as an active material for a negative electrode in a Li battery, the electrochemical lithiation of pure Al metal is known to be quite difficult. In this work, we sought to clarify why an Al electrode hardly absorbs Li from a pure Al state, from the viewpoint of elasticity theory and thermodynamics. We consider two cases: (i) an AlLi compound with elastic strain due to volume expansion is formed in the Al matrix, and (ii) Li ions are absorbed into an Al electrode that has been pre-strained by rolling. These strain-energy effects are discussed with the aid of a chemical-potential diagram and the Gibbs-Duhem equation.