Open-framework aluminophosphates are an important class of inorganic crystalline compounds because of their rich structural chemistry and diverse properties. We have collected 312 openframework aluminophosphate crystal structures from published literature and established a database for these structures. For each aluminophosphate structure, we have assigned a unique index code and extracted its key chemical and crystallographic information from the original literature and the associated CIF file, such as the name, chemical formula, extra-framework species, Al/P ratio, space group, and unit cell parameters of the compound. More importantly, we have calculated the topological features for each aluminophosphate framework, including local connectivity, framework dimension, coordination sequences, vertex symbols, topology density, and the largest ring. To help experimental chemists identify their products, we have also calculated theoretical XRD peaks for all aluminophosphate structures. this database will provide important insight into understanding the structural chemistry of open-framework aluminophosphate compounds.

Coating polypyrrole (PPy) on the surface of cathode materials could effectively enhance the electrochemical performances of lithium ion batteries (LIBs). The effect of the coated PPy layer thickness on the electrochemical performance, however, has not been well revealed. In this work, we study experimentally the impact of the PPy coating layer thickness on the electrochemical performance of the cathode materials in LIBs. The surface‐coated LiNi0.5Co0.2Mn0.3O2 (NCM) with different PPy layer thickness was synthesized by in situ growing PPy on the surface of NCM. When these coated‐samples were tested as cathodes of LIBs, the sample PPy5 with a coating layer thickness of about 3 nm exhibits an optimum electrochemical performance. More detailed analysis of electrochemical impedance spectra and structures for the cycled electrodes show that the coating layer of about 3 nm endows the PPy5 cathode with the smallest resistance and the most stable structure, ensuring its excellent cycle stability and rate performance. Comparatively, coating layer thickness of about 1 nm is too thin to maintain the structural stability of PPy1 cathode during a long‐term cycle, and an over thick coating layer (approximately 5 nm) significantly increases the resistance due to the shedding of the electrode, which results in their poor electrochemical performance. The results given in present paper will provide the guidance for optimizing the electrochemical properties of conductive polymer coated cathode materials.