Florian Schipper

Stabilizing nickel-rich layered cathode materials by a high-charge cation doping strategy: zirconium-doped LiNi0.6Co0.2Mn0.2O2

Ni-rich layered lithiated transition metal oxides Li[NixCoyMnz]O2 (x + y + z = 1) are the most promising materials for positive electrodes for advanced Li-ion batteries. However, one of the drawbacks of these materials is their low intrinsic stability during prolonged cycling. In this work, we present lattice doping as a strategy to improve the structural stability and voltage fade on prolonged cycling of LiNi0.6Co0.2Mn0.2O2 (NCM-622) doped with zirconium (+4). It was found that LiNi0.56Zr0.04Co0.2Mn0.2O2 is stable upon galvanostatic cycling, in contrast to the undoped material, which undergoes partial structural layered-to-spinel transformation during cycling. The current study provides sub-nanoscale insight into the role of Zr4+ doping on such a transformation in Ni-rich Li[NixCoyMnz]O2 materials by adopting a combined experimental and first-principles theory approach. A possible mechanism for a Ni-mediated layered-to-spinel transformation in Ni-rich NCMs is also proposed.

A brief review: Past, present and future of lithium ion batteries

The review summarizes the development of lithium ion batteries beginning with the research of the 1970–1980s which lead to modern intercalation type batteries. Following the history of lithium ion batteries, material developments are outlined with a look at cathode materials, electrolyte solutions and anode materials. Finally, with lithium sulfur and lithium oxygen batteries two post intercalation type lithium batteries are discussed. The focus of the material discussions lies on basic understanding, problems and opportunities related to the materials.

Enhanced capacity and lower mean charge voltage of Li-rich cathodes for lithium ion batteries resulting from low-temperature electrochemical activation

High capacity and high energy cathodes prepared from Li-rich 0.35Li2MnO3·0.65Li[Mn0.45Ni0.35Co0.20]O2 materials must be activated in Li-ion cells prior to normal cycling, in order to achieve their high discharge capacity of >250 mA h g−1. Activation is performed by charging the electrodes to potentials of 4.7–4.8 V vs. Li/Li+. This communication reports on the discovery that electrochemical activation of these cathode materials at low temperatures (0–15 °C) increases their discharge capacity, lowers average charge voltage, and diminishes voltage hysteresis. Work with the above mentioned material is reported as a representative example.