Abstract Ni-rich layered oxides (Ni-rich NCM) have received much attention owing to their high specific capacity, but poor cycling performance attributed to their inferior surface properties is still considered to… Click to show full abstract
Abstract Ni-rich layered oxides (Ni-rich NCM) have received much attention owing to their high specific capacity, but poor cycling performance attributed to their inferior surface properties is still considered to be a bottleneck preventing the expansion of the wider adoption of these materials in lithium-ion batteries (LIBs). In this work, we propose one-step efficient surface modification process which utilizes an organic surfactant (SDS) with a sulfate functional group in order to improve the surface stability of Ni-rich NCM materials. The surface modification provides a sulfate-embedded cathode-electrolyte interphase (CEI) layer on the Ni-rich NCM surface, which includes a SOx functional group. All of cells employing SDS-treated NCM cathode exhibit higher specific capacity retention after 100 cycles. Among these, the cell cycled with the 0.5% SDS-treated Ni-rich NCM cathode exhibited specific capacity retention of 91.9%, which is a remarkable increase compared with the cell cycled with bare NCM811 (69.6%). Additional analyses of the cycled electrodes indicated that the better cycling performance of the SDS-treated NCM811 cathode is attributable to the stabilization of the NCM811 surface; less electrolyte decomposition was observed in a cycled SDS-treated NCM811 cathode when analyzed by SEM, EIS, and XPS.
               
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