Preparation and characterization of Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O2 cathode materials for lithium-ion battery

摘要

Lithium-rich cathode materials Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O2 with (sample SF) and without (sample SP) formamide was synthesized by a spray-dry method. The crystalline structure and particle morphology of as-prepared materials were characterized by X-ray diffraction and scanning electron microscope. The specific surface area (SSA) of the Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O2 prepared from different routes was determined by a five-point Brunauer-Emmett-Teller (BET) method using N2 as absorbate gas. Being compared with the material synthesized without spray-drying process (sample CP), sample SP has much higher SSA. The additive formamide is helpful to form regular and solid precursor particles in spray-drying process, which results in a slightly aggregation of grains and reduction of SSA for sample SF. The electrochemical activities of the materials are closely related to their morphology and SSA. In the voltage range of 2-4.8 Vat 25 °C, sample SP present a discharge capacity of 257 mAh g~(-1) at 0.1 C rate and 170 mAh g~(-1) at 1 C rate. The sample CP delivered only 136 mAh g~(-1) when discharged at 1 C rate. The elevated specific capacity and rate capability are attributed to smaller primary particle and higher SSA. Both cycle performance and rate capability of Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O2 were improved when formamide was used in spray-dry process. Discharge capacity of SF is 140.5 mAh g~(-1) at 2 C rate, and that of SP is 132.3 mAh g~(-1). Overlarge SSA of SP may provoke serious side reaction, so that its electrochemical performance was deteriorated.