Separating Li-ion and Electron Conduction Pathways to Realize Robust Cathode Interfaces

Abstract

Cathode interfacial electron/Li-ion transportation is equally important to enable high-rate performance and high cycling stability of a lithium-ion battery, thereby cathode surface engineering and cathode electrolyte interphase (CEI) regulation have gained tremendous research efforts. Herein, to balance and optimize the interfacial electron/Li-ion transfer, we propose a novel design strategy to construct the respective conduction pathway for Li-ion and electron interfacial transfer, which is realized by anchoring inert and electron conductive island particles on the LiCoO2 particle surface. Such an interfacial design can realize stable interfacial electron conductivity through the CEI-free island particles, thus significantly enhancing the overall interfacial charge transfer kinetics and cycling stability. Further combining surface Ti-doping to form a thin and stable CEI layer for fast Li-ion transfer, this work demonstrates that surface doping and island particle anchoring can work synergistically to achieve high-rate and high-stability cycling performance. Full cell cycling stability reaches 97% at 2C rate after 200 cycles. The proposed interfacial design strategy and our successful demonstrations together stress that maintaining high interfacial conductivity for electron and Li-ion is equally important to realize a robust cathode interface.