No abstract

A new setup for in situ experiments with up to eight electrochemical cells, especially battery coin cells, and the corresponding custom‐made in situ cells are presented. The setup is primarily optimized for synchrotron powder diffraction measurements. As a newly constructed experimental setup, the in situ coin cell holder was tested for positional errors of the cells and the reliability of the diffraction as well as electrochemical measurements. The overall performance characteristics of the sample holder are illustrated by measurements on LiMn2O4 and LiNi0.35Fe0.3Mn1.35O4 spinel‐based positive electrode materials.

Accurate capacity estimation is crucial for the reliable and safe operation of lithium-ion batteries. In particular, exploiting the relaxation voltage curve features could enable battery capacity estimation without additional cycling information. Here, we report the study of three datasets comprising 130 commercial lithium-ion cells cycled under various conditions to evaluate the capacity estimation approach. One dataset is collected for model building from batteries with LiNi0.86Co0.11Al0.03O2-based positive electrodes. The other two datasets, used for validation, are obtained from batteries with LiNi0.83Co0.11Mn0.07O2-based positive electrodes and batteries with the blend of Li(NiCoMn)O2 - Li(NiCoAl)O2 positive electrodes. Base models that use machine learning methods are employed to estimate the battery capacity using features derived from the relaxation voltage profiles. The best model achieves a root-mean-square error of 1.1% for the dataset used for the model building. A transfer learning model is then developed by adding a featured linear transformation to the base model. This extended model achieves a root-mean-square error of less than 1.7% on the datasets used for the model validation, indicating the successful applicability of the capacity estimation approach utilizing cell voltage relaxation.

No abstract

Commercially available 18650 Li-ion batteries are considered for high energy density storage and usage in mobile applications as well as to store energy from intermittent energy sources. This has triggered intense research for suitable electrode and electrolyte materials, while their current stateof-the-art, temperature dependent performance is hardly described in detail. The fatigue process in two brands of rechargeable commercial high-energy Li-ion batteries (18650-type, 3500 mAh, LiNi 0.83 Mn 0.07 Co 0.11 O 2 (NMC-811) and LiNi 0.86 Co 0.11 Al 0.03 O 2 (NCA)) as a function of cycling temperature has been investigated using in-situ neutron powder diffraction (NPD) and electrochemical impedance spectroscopy (EIS). The batteries (~140) were cycled at conditions specified by the manufacturer and simulated realistic user conditions with good statistics. Cycling temperature (25, 35 and 45 °C) had a significant influence on the capacity fade with 35 °C showing the highest capacity retention. The NCA

No abstract

No abstract

The suitability of multication doping to stabilize the disordered Fd 3̅ m structure in a spinel is reported here. In this work, LiNi 0.3 Cu 0.1 Fe 0.2 Mn 1.4 O 4 was synthesized via a sol–gel route at a calcination temperature of 850 °C. LiNi 0.3 Cu 0.1 Fe 0.2 Mn 1.4 O 4 is evaluated as positive electrode material in a voltage range between 3.5 and 5.3 V (vs Li + /Li) with an initial specific discharge capacity of 126 mAh g –1 at a rate of C /2. This material shows good cycling stability with a capacity retention of 89% after 200 cycles and an excellent rate capability with the discharge capacity reaching 78 mAh g –1 at a rate of 20 C . In operando X-ray diffraction (XRD) measurements with a laboratory X-ray source between 3.5 and 5.3 V at a rate of C /10 reveal that the (de)lithiation occurs via a solid-solution mechanism where a local variation of lithium content is observed. A simplified estimation based on the in operando XRD analysis suggests that around 17–31 mAh g –1 of discharge capacity in the first cycle is used for a reductive parasitic reaction, hindering a full lithiation of the positive electrode at the end of the first discharge.