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Metal halide perovskite materials have made a significant breakthrough in diverse research fields over the last decade because of their high photoelectric conversion capability. However, there is a lack of...

LiNiCoMnO (NCM) is regarded as a promising material for next-generation lithium ion batteries due to the high capacity, but its practical applications are limited by the poor electronic conductivity. Here, a one-step method is used to prepare carbon coated LiNiCoMnO (NCM/C) by applying active carbon as reaction matrix. TEM shows LiNiCoMnO particles are homogeneously coated by carbon with a thickness about 10 nm. NCM/C delivers the discharge capacity of 191.2 mAh g at 0.5 C (85 mA g) with a columbic efficiency of 91.1%. At 40 C (6800 mA g), the discharge capacity of NCM/C is 54.6 mAh g, whereas NCM prepared through sol-gel route only delivers 13.2 mAh g. After 100 charge and discharge cycles at 1 C (170 mA g) the capacity retention is 90.3% for NCM/C, whereas it is only 72.4% for NCM. The superior charge/discharge performance of NCM/C owes much to the carbon coating layer, which is not only helpful to increase the electronic conductivity but also contributive to inhibit the side reactions between LiNiCoMnO and the liquid electrolyte.

The interface chemistry and evolution of the evaporated perovskite films on ITO, pedot/ITO, Si and glass substrates are studied. As evidenced by X-ray diffraction and X-ray photoemission spectroscopy (XPS) results, the PbI2 phase is found to be inevitably formed at the very initial growth stage, even under the conditions of a MAI-rich environment. The extremely low binding energy of adsorbed MAI particles on all the above substrates, as compared to that of PbI2 particles, is responsible for the presence of the PbI2 phase at the interface. The formation of both hole and electron barriers at the interface of PbI2/MAPbI3, as evidenced by XPS measurements, could block carrier transport into the electrode and thus deteriorate solar cell performance. This result reveals the origin of the poor performance of perovskite solar cells (PSCs) by the vacuum evaporation method, and may help to improve the performance of PSCs made using the vacuum evaporation method.