LiNi_0.5Mn_1.5O₄ (LNMO) cathode active materials for lithium‐ion batteries have been investigated for over 20 years. Despite all this effort, it has not been possible to transfer their favorable properties into applicable, stable battery cells. To make further progress, the research perspective on these spinel type materials needs to be updated and a number of persisting misconceptions on LNMO have to be overcome. Therefore, the current knowledge on LNMO is summarized and controversial points are addressed by detailed considerations on the composition and crystallography of LNMO. The findings are supported by an in‐situ high temperature X‐ray diffraction study and the investigation of four different types of LNMO materials, including Mn(III) rich ordered LNMO, and disordered LNMO with low Mn(III) content. It is shown that the importance of cation order is limited to a small composition range. Furthermore, new evidence contradicting the idea of oxygen defects in LNMO is presented and an enhanced classification of LNMO based on the Ni content of the spinel phase is proposed. Moreover, a balanced chemical equation for the formation of LNMO is presented, allowing for comprehensive calculations of key properties of LNMO materials. Finally, suitable target compositions and calcination programs are suggested to obtain better LNMO materials.

Developing hierarchically layered cathode materials with high performance is key to further improving advanced lithium-ion batteries, but it is challenging to synthesize such systems with controllable shape on a large scale. We used a high-shear mixer to continuously prepare flower-like hydroxide precursors via a co-precipitation method in a continuous stirred-tank reactor (CSTR). After the lithiation reaction, hierarchical lithium transition-metal oxides with predominantly exposed electrochemically active {010} planes are produced. The electrochemical properties of these peculiar materials (i.e. LiNi_1/3Co_1/3Mn_1/3O₂, LiNi_0.6Co_0.2Mn_0.2O₂ and Li_1.2Ni_0.2Mn_0.6O₂) are demonstrated to be excellent. Particularly, LiNi_1/3Co_1/3Mn_1/3O₂ exhibits a durable high-rate capability with a capacity retention of 98.2% after 500 cycles at 20C between 2.7 and 4.3 V. This work provides a new technology to fabricate two-dimensional nanoarchitectured electrode materials. Moreover, the outstanding electrochemical properties of this hierarchically structured cathode material in combination with the scalable method make it highly interesting for commercialization.

A nanostructured, porous NCM cathode material is investigated regarding its behavior during electrode processing and electrochemical performance. The results are related to the densely packed NCM original material from which the nanostructure has been derived. Chemical composition and structural parameters are not affected by the nanostructuring process; changes are limited to the particle morphology in terms of primary particle size, specific surface area, and porosity. Electrodes containing a porous NCM material deliver lower adhesion strength values when adding identical amounts of PVDF binder. Increasing the binder fraction from four to six parts increases also the adhesion strength to an acceptable level without deteriorating the cell capacity. Despite initially high electrode porosities of 65–70%, electrodes with nanostructured NCM are capable of withstanding calendering to 40% porosity without destroying the porous particles. Full-cell tests with 50 mAh pouch cells and graphite anodes reveal substantially improved C-rate capabilities for the nanostructured material in relation to the commercial original NCM. The advantage increases with increasing C-rate and corresponds to shorter diffusion pathways in nanostructured NCM. Remarkably, even at low C-rates (C/20) where diffusion effects are considered secondary, porous NCM lies ahead of the original material. This can be explained by the higher surface area and thereby enlarged interface to the electrolyte, which eases delithiation. Long-term cycling up to 1100 cycles displayed further benefits for the nanostructured active material as one of the most prominent degradation factors, that is, crack formation and particle fragmentation, does not occur throughout the complete cycling procedure—in contrast to the bulk particles of original NCM.

The preparation of fully inkjet printed capacitors containing ceramic/polymer composites as the dielectric material is presented. Therefore, ceramic/polymer composite inks were developed, which allow a fast one-step fabrication of the composite thick films. Ba_0.6Sr_0.4TiO₃(BST) is used as the ceramic component and poly(methyl methacrylate) (PMMA) as the polymer. The use of such composites allows printing on flexible substrates. Furthermore, it results in improved values for the permittivity compared to pure polymers. Three composite inks with varying ratio of BST to PMMA were used for the fabrication of composite thick films consisting of 33, 50 and 66 vol% BST, respectively. All inks lead to homogeneous structures with precise transitions between the different layers in the capacitors. Besides the microstructures of the printed thick films, the dielectric properties were characterized by impedance spectroscopy over a frequency range of 100 Hz to 200 kHz. In addition, the influence of a larger ceramic particle size was investigated, to raise permittivity. The printed capacitors exhibited dielectric constants of 20 up to 55 at 1 kHz. Finally, the experimental results were compared to different theoretical models and their suitability for the prediction ofε_compositewas assessed.

Using hydrogen peroxide (H₂O₂), a novel approach was applied for the synthesis of LiNi_0.5Mn_1.5O₄ (LNMO) coated with Li₃PO₄ and doped with Al³⁺ and Ti⁴⁺ ions. The reaction between LNMO and H₂O₂ resulted in particles with a partially damaged surface. If the same reaction is done in the presence of lithium, aluminum, titanium, and phosphate ingredients, then all particle facets are intact and show no sign of destruction. It appears that the H₂O₂ decomposition activates the LNMO surface, generating perfect conditions for the homogeneous deposition of the Li, Al, Ti, and phosphate ions. Electrochemical investigations show a very slow fading process during the cycling, and even after more than 500 cycles, the obtained cathode material shows a high specific capacity of 127 mAh g^–1 (at 1 C) (∼98% capacity retention) and an excellent Coulombic efficiency (99.5%).