Mechanical and temperature effects on the performance of anodes in electrochemical batteries
Sergei Manzhos (National Uni. of Singapore), Oleksandr Malyi (National University of Singapore), Yang Wei, Koh (Bioinformatics Institute, A*STAR)
Materials for Extreme Environments: Multiscale Experiments and Simulations
Mon 4:20 - 5:40
Salomon 203
Metal ion batteries are a key technology that enables mobile electronics today. While Li batteries are widely used, it is non-Li batteries, such as Na and Mg batteries, that hold most promise for large-scale electricity storage (required with a growing share of green yet intermittent sources such as solar and wind) and high energy density applications (such as all-electric vehicles). The development of electrodes for Na and Mg batteries is a difficult task, as storage energetics, maximum metal uptake (determining battery capacity), and diffusion properties (determining battery rate capability) are all less favorable compared to Li storage [1, 2, 3]. The last property is especially critical, as bulk storage requires a high rate capability to be economic [4]. We show that it is possible to modulate the diffusion barrier in some of the most promising anode materials by mechanical deformations and temperature. For example, the diffusion barrier of Na and Mg in Si is much higher (by about 0.5 eV) compared to Li, but it can be lowered by up to 0.2 eV if a strain of a few per cent is imposed. On graphene, on the contrary, Na diffusion barrier is lower than that of Li, but buckling can increase the barrier by about 2/3rds. Contributions of zero-point and finite temperature vibrations are usually ignored in analyses of diffusion properties of electrodes. We show that contributions of vibrations to the diffusion barrier can reach several kT at room temperature, are strongly temperature-dependent and non-monotonic. 1. O. I. Malyi, T. L. Tan, S. Manzhos, Appl. Phys. Express 6 (2013) 027301 2. O. I. Malyi, T. L. Tan, S. Manzhos, J. Power Sources 233 (2013) 341 3. O. I. Malyi, T. L. Tan, S. Manzhos, Nano Energy, submitted 4. E. Barbour et al., Energy Environ. Sci. 5 (2012) 5425