Feasibility of mesocarbon mircrobead as an anode for lithium ion batteries work under 115 MPa external high pressure

Abstract Exploration deep into the ocean and earth calls for power systems that can tolerant extremely high pressure, e.g. the pressure reaches up to 110 MPa at seafloor of Mariana Trench. In this work, we report for the first time the effects of 115 MPa external high pressure on mesocarbon microbead (MCMB) as an anode for lithium ion battery (LIB), from crystal structural variation and Li+ ion diffusion in material, to micromorphology evolution of material and electrode, as well as electrochemical performance of both coin cells and 42 Ah format pouch cells. Results reveal that the crystal change of MCMB is elastic and the pores within the particles are compressed, while the micromorphology is kept when pressure applied. The electrode porosity is remarkably reduced. However, the electrochemical performance is not affected when the discharge/charge rate is moderate. Moreover, theoretical calculation results suggest that high external pressure over 4.2 GPa may affect the diffusion of Li+ ions differently in dilute and densely lithiated graphite. These findings demonstrate that LIB based on MCMB anode could withstand pressure at least up to 115 MPa, which is critical for future deep sea and under-earth explorations.