Separating Li-ion and electron conduction pathways to realize robust cathode interfaces
Abstract
Cathode interfacial electron/Li-ion transportation is equally important to realize high-rate performance and high cycling stability of lithium-ion batteries; thus, cathode surface engineering and cathode electrolyte interphase (CEI) regulation have gained tremendous research interest. Herein, to balance and optimize the interfacial electron/Li-ion transfer, we propose a novel design strategy to construct the respective conduction pathway for interfacial electron transfer or Li-ion transfer, which is realized by anchoring inert and electron-conductive island particles on an LiCoO2 particle surface. Such an interfacial design can realize stable interfacial electron conductivity through the CEI-free island particles, thereby significantly enhancing the overall interfacial charge transfer kinetics and cycling stability. Furthermore, combining the 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 a rate of 2C after 200 cycles. The proposed interfacial design strategy and our successful demonstration together emphasize that maintaining high interfacial conductivity for electrons and Li-ions is equally important to realize a robust cathode interface.