Growth of dendritic protrusions leading to short circuits of cells is presently the largest barrier to widespread usage of lithium metal anodes in commercial lithium ion batteries. Dendrite growth becomes more severe at high current density and low temperature operations because of the onset of diffusion limitations. Improving the elastic-plastic mechanical properties of the electrolyte material can significantly suppress the propagation of dendritic protrusions[1]. However, it has also been argued that enhanced electrolyte transport properties can decrease the propensity for dendrite growth. For example, increased diffusivity of the electrolyte at higher temperature leads to stable deposition of lithium[2], as does increasing the cation transference number of the electrolyte[3].

The propensity for growth of dendritic protrusions can be estimated by solving the mechanical equilibrium, mass transport and charge transport equations, coupled with the nonlinear Butler-Volmer relation. Based on this computational approach, a map correlating growth during operation at 75% of the limiting current density to the electrolyte shear modulus and transference number (see Figure 1) has been developed, showing regimes in which prevention of dendritic protrusion is possible. The results are consistent with experimental observations[4] of dendrite growth in liquid and polymer (PEO) based electrolytes (demarcated by the red regions). This phase-map is expected to help in designing new electrolyte materials that promote dendrite-free lithium deposition.

References

1. Monroe, C. and J. Newman, The impact of elastic deformation on deposition kinetics at lithium/polymer interfaces. Journal of the Electrochemical Society, 2005. 152(2): p. A396-A404.

2. Love, C.T., O.A. Baturina, and K.E. Swider-Lyons, Observation of Lithium Dendrites at Ambient Temperature and Below. Ecs Electrochemistry Letters, 2015. 4(2): p. A24-A27.

3. Tikekar, M.D., L.A. Archer, and D.L. Koch, Stability Analysis of Electrodeposition across a Structured Electrolyte with Immobilized Anions. Journal of the Electrochemical Society, 2014. 161(6): p. A847-A855.

4. Brissot, C., et al., Dendritic growth mechanisms in lithium/polymer cells. Journal of Power Sources, 1999. 81: p. 925-929.