Self-Regulatory Lean-Electrolyte Flow for Building 600 Wh Kg^-1-Level Rechargeable Lithium Batteries.

Abstract

Reducing excess electrolytes offers a promising approach to improve the specific energy of electrochemical energy storage devices. However, using lean electrolytes presents a significant challenge for porous electrode materials due to heterogeneous wetting. The spontaneous wetting of nano- or meso-pores within particles, though seldom discussed, adversely affects wetting under lean electrolyte conditions. Herein, this undesired wetting behavior is mitigated by enlarging the pore-throat ratio, enabling Li-rich layered oxide to function effectively at very low electrolyte/capacity (E/C) ratio of 1.4 g Ah^-1. The resulting pouch cell achieves 606 Wh kg^-1 and retains 80% capacity (75% energy) after 70 cycles. Through imaging techniques and molecular dynamics simulations, it is demonstrated that the pore-throat ratio effectively determines the permeability of electrolyte within particles. By elucidating pore-relating mechanisms, this work unveils promising potential of manipulating pore structures in porous electrode materials, an approach that can be applied to improve the specific energy of other devices including semi-solid-state lithium batteries.