Torsten Brezesinski

Karlsruhe Institute of Technology | KIT · Institute of Nanotechnology

The high‐entropy approach is applied to monoclinic Prussian White (PW) Na‐ion cathodes to address the issue of unfavorable multilevel phase transitions upon electrochemical cycling, leading to poor stability and capacity decay. A series of Mn‐based samples with up to six metal species sharing the N‐coordinated positions was synthesized. The materia...

The high‐entropy approach is applied to monoclinic Prussian White (PW) Na‐ion cathodes to address the issue of unfavorable multilevel phase transitions upon electrochemical cycling, leading to poor stability and capacity decay. A series of Mn‐based samples with up to six metal species sharing the N‐coordinated positions was synthesized. The materia...

Superionic conductors are key components of solid‐state batteries (SSBs). Multicomponent or high‐entropy materials, offering a vast compositional space for tailoring properties, have recently attracted attention as novel solid electrolytes (SEs). However, the influence of synthetic parameters on ionic conductivity in compositionally complex SEs has...

Silicon (Si) is anticipated to become one of the most promising anode materials for high‐energy‐density solid‐state battery (SSB) applications owing to its high theoretical specific capacity and low working potential. This work compares the electrochemical behavior of slurry‐cast electrodes in Si|Li 6 PS 5 Cl|In/InLi cells, with micron‐sized Si par...

Invited for this issue's Front Cover is the group of Torsten Brezesinski at KIT. The cover picture presents the metaphor of cathode particles, their morphology and underlying rate capability as racers with different performances. Here we present a way to think about single crystal layered oxide cathodes, which stand apart from more common polycryst...

With the increasing demand for safer, more stable, and energy dense batteries, investigations into single crystal layered oxide cathodes have gained momentum. However, translating considerations from polycrystalline to single‐crystalline particles and their ensembles is not one‐to‐one. Lithium diffusion path length, surface, dopants and coatings, a...

Layered Ni-rich oxides are attractive cathode active materials for secondary battery applications. Combining them with inorganic superionic conductors and high-capacity anodes can significantly increase energy density. Herein we successfully synthesized...

Studying chemical reactions in real time can provide unparalleled insight into the evolution of intermediate species and can provide guidance to optimize the reaction conditions. For solid-state synthesis reactions, powder diffraction has been demonstrated as an effective tool for resolving the structural evolution taking place upon heating. The sy...

The pursuit of higher energy density in lithium-ion batteries has driven the increase of the nickel content in lithium nickel cobalt manganese oxide cathode active materials (CAMs), ultimately approaching LiNiO 2 (LNO). The downside of the high specific capacity of LNO is more severe degradation of the CAM during battery operation. A common approac...

Single-crystal LiNi1-x-yCoxMnyO2 (SC-NCM, x + y + z = 1) cathodes are renowned for their high structural stability and reduced accumulation of adverse side products during long-term cycling. While advances have been made using SC-NCM cathode materials, careful studies of cathode degradation mechanisms are scarce. Herein, we employed quasi single-cr...

Single‐crystal LiNi x Co y Mn z O 2 (SC‐NCM, x + y + z =1) cathodes are renowned for their high structural stability and reduced accumulation of adverse side products during long‐term cycling. While advances have been made using SC‐NCM cathode materials, careful studies of cathode degradation mechanisms are scarce. Herein, we employed quasi single‐...

As contemporary battery applications such as electric vehicles demand higher energy densities, layered LiNiO2 (LNO) could contribute as the end-member of the LiNi1-x-yCoxMnyO2 (NCM) family with the highest extractable specific capacity in a practical voltage window. Achieving high capacities requires among other things a defect free crystal structu...

Sodium-ion batteries (SIBs) see intensive research and commercialization efforts, aiming to establish them as an alternative to lithium-ion batteries. Among the reported cathode material families for SIBs, Na-deficient P2-type layered oxides are promising candidates, benefiting from fast sodium diffusion and therefore high charge/discharge rates. H...

Using scanning transmission electron microscopy, along with electron energy loss spectroscopy, under cryogenic conditions, we demonstrate transition-metal dissolution from a layered Ni-rich oxide cathode material and subsequent diffusion into the...

To increase the specific capacity of LiNi 1-x-y Co x Mn y O 2 (NCM) cathode active materials, academia and industry are aiming at a higher nickel content. The end member of this family, LiNiO 2 (LNO), offers the highest practical specific capacity, but suffers from morphological and structural instabilities during electrochemical cycling. Especiall...

Layered transition metal oxides (LTMOs), such as the LiNixCoyMn1−x−yO2 family, are the primary class of cathode active materials (CAMs) commercialized and studied for conventional lithium-ion (LIB) and solid-state battery (SSB)...

Protective coatings are required to address interfacial incompatibility issues in composite cathodes made from Ni‐rich layered oxides and lithium thiophosphate solid electrolytes (SEs), one of the most promising combinations of materials for high energy and power density solid‐state battery (SSB) applications. Herein, the preparation of conformal Z...

Lithium‐thiophosphate‐based all‐solid‐state batteries (ASSBs) are increasingly attracting attention for high‐density electrochemical energy storage. In this work, the cycling performance of single and polycrystalline forms of LiNixCoyMnzO2 (NCM, with ≥83% Ni content) cathode active materials in ASSB cells with an Li4Ti5O12 composite anode is explor...

Cobalt oxides are technologically important materials, especially when lithiated for application as Li-ion cathodes. However, several phases may crystallize during solid-state synthesis in the Li–Co–O–H system. The solid-state reactions of LiOH·H2O with both β-Co(OH)2 and Co3O4 have been investigated here through the combined use of high-resolution...

Bulk-type solid-state batteries (SSBs) composed of lithium thiophosphate superionic solid electrolytes (SEs) and high-capacity cathode active materials (CAMs) have recently attracted much attention for their potential application in next-generation electrochemical energy storage. However, compatibility issues between the key components in this kind...

Lithium-ion batteries (LIBs) are essential for modern life, and their improvement is crucial for the more widespread adoption of electric vehicles. [1] Layered lithium transition metal oxides, such as LiNi x Co y Mn z O 2 (often referred to as NCM or NMC), are among the most widely used cathode active materials (CAMs) for automotive applications, o...

LiNiO 2 has been long considered as a promising cathode material owing to its high practical energy density [1,2]. However, structural and surface instabilities, coupled with complexities in the synthesis, have thus far prevented its commercialisation [3]. In this talk I will review our recent work towards the use of LiNiO 2 as an actual cathode so...

ASSBs (all-solid-state batteries) are promoted as an energy dense and safe alternative to current Li-ion batteries (LIBs) and attract great interest from academia and industry. In contrast to LIBs, which employ a liquid organic electrolyte, they utilize a solid electrolyte. This substitution promises to eliminate the flammability of the battery and...

Bulk-type solid-state batteries (SSBs) constitute a promising next-generation technology for electrochemical energy storage. However, in order for SSBs to become competitive with mature battery technologies, (electro)chemically stable, superionic solid electrolytes are much needed. Multicomponent or high-entropy lithium argyrodites have recently at...

Driven by demand for greater energy densities, Ni-rich cathode materials, such as lithium nickel cobalt manganese (NCM) and nickel cobalt aluminum (NCA) oxides, with compositions approaching the lithium nickel oxide (LiNiO 2) end-member have been investigated intensively. While such compositions are targeted assuming the redox activity of nickel wi...

P2-type layered oxides with the general Na-deficient composition NaxTMO2 (x < 1, TM: transition metal) are a promising class of cathode materials for sodium-ion batteries. The open Na+ transport pathways present in the structure lead to low diffusion barriers and enable high charge/discharge rates. However, a phase transition from P2 to O2 structur...

Oxide semiconductors are becoming the materials of choice for modern‐day display industries. The performance of solution‐processed oxide thin film transistors (TFTs) has also improved dramatically over the last few years. However, while oxygen deficient n‐type semiconductors can demonstrate excellent electronic transport, the performance of p‐type...

Configurational Entropy In article number 2202372, Yuan Ma, Ben Breitung, Torsten Brezesinski, and co‐workers report the preparation and characterization of Mn‐based multicomponent hexacyanoferrate cathodes for application in Na‐ion batteries. Systematic comparison of the structural, chemical, and electrochemical properties of high‐, medium‐ and lo...

LiNiO 2 has been long considered as a promising cathode material owing to its high practical energy density. However, structural and surface instabilities, coupled with complexities in the LiNiO 2 synthesis, have thus far prevented its commercialisation. To address issues with the material’s stability during synthesis and cycling, the use of an amm...

Energy coverage In cover article ntls.20210105, Michael Bojdys et al. introduce a semi‐conducting porous organic polymer network, replacing all conventional additives in Si‐Li anodes and enabling the one‐pot production of moreperformant, flexible and thermally stable electrodes.

Solid‐state batteries (SSBs) currently attract great attention as a potentially safe electrochemical high‐energy storage concept. However, several issues still prevent SSBs from outperforming today's lithium‐ion batteries based on liquid electrolytes. One major challenge is related to the design of cathode active materials (CAMs) that are compatibl...

Nanoparticle Protective Coatings In article number 2111829, Yuan Ma, Jürgen Janek, Torsten Brezesinski, and co‐workers propose a new coating strategy for layered Ni‐rich oxide cathode materials employing preformed (non‐agglomerated) nanoparticles dispersed in a liquid solvent. This approach leads to much improved cycling performance and stability a...

The research and development of advanced nanocoatings for high-capacity cathode materials is currently a hot topic in the field of solid-state batteries (SSBs). Protective surface coatings prevent direct contact between the cathode material and solid electrolyte, thereby inhibiting detrimental interfacial decomposition reactions. This is particular...

The operation of combined mass spectrometry and electrochemistry setups has recently become a powerful approach for the in situ analysis of gas evolution in batteries. It allows for real-time insights and mechanistic understanding into different processes, including battery formation, operation, degradation, and behavior under stress conditions. Im...

Mn‐based hexacyanoferrate (Mn‐HCF) cathodes for Na‐ion batteries usually suffer from poor reversibility and capacity decay resulting from unfavorable phase transitions and structural degradation during cycling. To address this issue, the high‐entropy concept is here applied to Mn‐HCF materials, significantly improving the sodium storage capabilitie...

Silicon‐based anodes with lithium ions as charge carriers have the highest predicted theoretical specific capacity of 3579 mA h g⁻¹ (for Li15Si4). Contemporary electrodes do not achieve this theoretical value largely because conventional production paradigms rely on the mixing of weakly coordinated components. In this paper, a semiconductive triazi...

This short perspective summarizes recent findings on the role of residual lithium present on the surface of layered Ni-rich oxide cathode materials in liquid- and solid-electrolyte based batteries, with emphasis placed on the carbonate species. Challenges and future research opportunities in the development of carbonate-containing protective nanoco...

LiNiO 2 (LNO) is a high energy density cathode material, yet it has been plagued by poor cycling performance and thermal instability. Adding dopants, such as Mg ²⁺ , is a common strategy to balance cycling performance and energy density. So far, the influence of Mg ²⁺ on the crystal structure remained ambiguous, especially when small industrially r...

High-entropy materials with tailorable properties are receiving increasing interest for energy applications. Among them, (disordered) rock-salt oxyfluorides hold promise as next-generation cathodes for use in secondary batteries. Here, we study the degradation behavior of a high-entropy oxyfluoride cathode material in lithium cells in situ via acou...

Inorganic solid‐state batteries are attracting significant interest as a contender to conventional liquid electrolyte‐based lithium‐ion batteries but still suffer from several limitations. The search for advanced coatings for protecting cathode materials in solid‐state batteries to achieve interfacial stability is a continuing challenge. In the pre...

Improving the interfacial stability between cathode active material (CAM) and solid electrolyte (SE) is a vital step toward the development of high‐performance solid‐state batteries (SSBs). One of the challenges plaguing this field is an economical and scalable approach to fabricate high‐quality protective coatings on the CAM particles. A new wet‐c...

LiNiO2 has long been considered a promising cathode material owing to its high energy density. However, structural and surface instabilities, coupled with its complex synthesis, have thus far prevented its commercialisation. To address these issues, we demonstrate here the use of an ammonium tungstate flux to modify both the crystal structure and p...

Solid-state batteries (SSBs) are a promising next step in electrochemical energy storage but are plagued by a number of problems. In this study, we demonstrate the recurring issue of mechanical degradation because of volume changes in layered Ni-rich oxide cathode materials in thiophosphate-based SSBs. Specifically, we explore superionic solid elec...

In recent years, high-entropy oxides are receiving increasing attention for electrochemical energy-storage applications. Among them, the rocksalt (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 )O (HEO) has been shown to be a promising high-capacity anode material. Because high-entropy oxides constitute a new class of electrode materials, systematic understand...

The energy density of layered oxide cathode materials increases with their Ni content, while the stability decreases and degradation becomes more severe. A common strategy to mitigate or prevent degradation is the application of protective coatings on the particle surfaces. In this article, a room‐temperature, liquid‐phase reaction of trimethylalum...

The recent achievements following the application of single-crystalline (SC) cathode material in solid-state batteries are discussed in this mini-review. The characteristics of SC and poly-crystalline (PC) cathode materials are explored, with emphasis on the kinetic and mechanical properties. The critical factors influencing their performance in li...

Layered Li(Ni1−x−yCoxMny)O2 (NCM, with Ni ≥ 0.8) cathode materials are essential in achieving high energy densities in the next generation of lithium-ion batteries. To extend the materials' lifetime, it is necessary to understand the role played by crystal defects in the degradation during electrochemical cycling. In this study, NCM851005 (85% Ni)...

In this study, the preparation of anatase TiO2 nanocrystals via a facile non-aqueous sol–gel route and their characterization are reported. The 3–4 nm particles are readily dispersable in aqueous media and show excellent photoreactivity in terms of rhodamine B degradation. The catalytic performance can be further increased considerably by doping wi...

Cathode Materials In article number 2101342, Yuan Ma, Ben Breitung, Torsten Brezesinski and co-workers report the introduction of high (configurational) entropy into Prussian blue analogues to achieve a stable cathode host material for reversible sodium storage. Especially, Nax(FeMnNiCuCo)[Fe(CN)6] is shown to exhibit much improved cycling performa...

Solid-state batteries (SSBs) have been touted as the next major milestone for electrochemical energy storage, improving safety and enabling higher energy densities. LiNiO2 (LNO) has long been considered a promising cathode material; however, its commercial implementation is complicated by stability issues, including reactivity toward the electrolyt...

Prussian blue analogues (PBAs) are reported to be efficient sodium storage materials because of the unique advantages of their metal–organic framework structure. However, the issues of low specific capacity and poor reversibility, caused by phase transitions during charge/discharge cycling, have thus far limited the applicability of these materials...

Superionic solid electrolytes are key to the development of advanced solid-state Li batteries. In recent years, various materials have been discovered, with ionic conductivities approaching or even exceeding those of carbonate-based liquid electrolytes used in high-performance Li-ion batteries. Among the different classes of inorganic solid electro...