Surface Modification of LiNi0.8 Co0.15 Al0.05 O2 Particles via Li3 PO4 Coating to Enable Aqueous Electrode Processing

The successful implementation of an aqueous-based electrode manufacturing process for nickel-rich cathode active materials is challenging due to their high water sensitivity. In this work, the surface of LiNi0.8 Co0.15 Al0.05 O2 (NCA) was modified with a lithium phosphate coating to investigate its ability to protect the active material during electrode production. The results illustrate that the coating amount is crucial and a compromise has to be made between protection during electrode processing and sufficient electronic conductivity through the particle surface. Cells with water-based electrodes containing NCA with an optimized amount of lithium phosphate had a slightly lower specific discharge capacity than cells with conventional N-methyl-2-pyrrolidone-based electrodes. Nonetheless, the cells with optimized water-based electrodes could compete in terms of cycle life.

Design of a 3D-Porous Structure with Residual Carbon for High-Performance Ni-Rich Cathode Materials

Recently, LiNi_0.8Co_0.1Mn_0.1O₂ has drawn much attention because of its high energy density. Here, 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ and the one with residual carbon have been synthesized using a resorcinol-formaldehyde-assisted sol-gel approach. Scanning electron microscopy images verify that the synthesized LiNi_0.8Co_0.1Mn_0.1O₂ possesses a 3D-porous morphology. X-ray photoelectron spectroscopy analysis and transmission electron microscopy-mapping images indicate the existence of residual carbon in the secondary particle of 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂. Furthermore, 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon exhibits outstanding electrochemical properties. At a current density of 1900 mA g^-1, the 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon can still deliver a reversible capacity of 113 . Moreover, after 150 cycles at 0.2 C, the capacity retention of 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon reaches to 95%. The excellent electrochemical properties can be ascribed to the unique 3D-porous morphology and residual carbon in the secondary particle.

Stabilizing the Electrode/Electrolyte Interface of LiNi0.8Co0.15Al0.05O2 through Tailoring Aluminum Distribution in Microspheres as Long-Life, High-Rate, and Safe Cathode for Lithium-Ion Batteries

The unstable electrode/electrolyte interface of high-capacity LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathodes, especially at a highly delithiated state, usually leads to the transformation of layered to spinel and/or rock-salt phases, resulting in drastic capacity fade and poor thermal stability. Herein, the Al-increased and Ni-,Co-decreased electrode surface is fabricated through tailoring element distribution in micrometer-sized spherical NCA secondary particles via coprecipitation and solid-state reactions, aimed at stabilizing the electrode/electrolyte interface during continuous cycles. As expected, it shows much extended cycle life, 93.6% capacity retention within 100 cycles, compared with that of 78.5% for the normal NCA. It also delivers large reversible capacity of about 140 mAh g^-1 even at 20 C, corresponding to energy density of around 480 Wh kg^-1, which is enhanced by 45% compared to that of the normal NCA (about 330 Wh kg^-1). Besides, the delayed heat emission temperature and reduced heat generation mean remarkably improved thermal stability. These foregoing improvements are ascribed to the Al-increased spherical secondary particle surface that stabilizes the electrode/electrolyte interface by protecting inner components from directly contacting with electrolyte and suppressing the side reaction on electrode surface between high oxidizing Ni⁴⁺ and electrolyte.

Facile strategy of NCA cation mixing regulation and its effect on electrochemical performance

The cation mixing of LiNi_0.8Co_0.15Al_0.05O₂ materials was regulated by a facile strategy via oxygen flow rate control during sintering, and the effect of cation mixing on the electrochemical performance was investigated by CR2025 coin cells tests.