Investigation of Li-ion transport in Li7P3S11 and solid-state lithium batteries

The high Li-ion conductivity of the Li7P3S11 sulfide-based solid electrolyte makes it a promising candidate for all-solid-state lithium batteries. The Li-ion transport over electrode-electrolyte and electrolyteelectrolyte interfaces, vital for the performance of solid-state batteries, is investigated by impedance spectroscopy and solid-state NMR experiments. An all-solid-state Li-ion battery is assembled with the Li7P3S11 electrolyte, nano-Li2S cathode and Li-In foil anode, showing a relatively large initial discharge capacity of 1139.5 m Ah/g at a current density of 0.064 m A/cm^ 2 retaining 850.0 m Ah/g after 30 cycles. Electrochemical impedance spectroscopy suggests that the decrease in capacity over cycling is due to the increased interfacial resistance between the electrode and the electrolyte. 1D exchange ^7Li NMR quantifies the interfacial Li-ion transport between the uncycled electrode and the electrolyte, resulting in a diffusion coefficient of 1.70(3) ×10^-14cm^2/s at 333 K and an energy barrier of 0.132 e V for the Li-ion transport between Li2S cathode and Li7P3S11 electrolyte. This indicates that the barrier for Li-ion transport over the electrode-electrolyte interface is small. However, the small diffusion coefficient for Li-ion diffusion between the Li2S and the Li7P3S11 suggests that these contact interfaces between electrode and electrolyte are relatively scarce, challenging the performance of these solid-state batteries.

Towards high performance cathodes for Na-ion batteries

The efficient and high energy storage in rechargeable lithium batteries has enabled portable electronic equipment,the demands on which are ever increasing as it also appears to be the technology of choice for electrical vehicles.Additionally,rechargeable lithium batteries appear to be suitable technology to stabilize the electrical grid and to lift the intermittency of renewable energy on a daily basis.Although lithium is relatively abundant in the Earth’s crust,

Thermodynamics of multi-sublattice battery active materials: from an extended regular solution theory to a phase-field model of LiMn_(y)Fe_(1-y)PO_(4)

Phase separation during the lithiation of redox-active materials is a critical factor affecting battery performance,including energy density,charging rates,and cycle life.Accurate physical descriptions of these materials are necessary for understanding underlying lithiation mechanisms,performance limitations,and optimizing energy storage devices.This work presents an extended regular solution model that captures mutual interactions between sublattices of multi-sublattice battery materials,typically synthesized by metal substitution.We apply the model to phospho-olivine materials and demonstrate its quantitative accuracy in predicting the composition-dependent redox shift of the plateaus of LiMn_(y)Fe_(1-y)PO_(4)(LFMP),LiCo_(y)Fe_(1-y)PO_(4)(LFCP),LiCo_(x)Mn_(y)Fe_(1-y)PO_(4)(LFMCP),as well as their phase separation behavior.Furthermore,we develop a phase-field model of LFMP that consistently matches experimental data and identifies LiMn0.4Fe0.6PO4 as a superior composition that favors a solid solution phase transition,making it ideal for high-power applications.