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Among current cathode materials, particular attention to Li/Mn-rich layered transition-metal oxides (LMR-NCM) emerged, due to their high energy content accompanied by concurrently low raw material cost. However, until today the step toward a successful market implementation is still impeded by substantial capacity and voltage fade phenomena upon cycling. Herein, we demonstrate a comprehensive structural and morphological approach to increase the long-term stability behavior of LMR-NCM materials within a lithium ion cell. Therefore, a recently introduced core–shell particle design concept was applied, which involves a Co-free and Mn-rich particle core and a low Co-containing shell. The resulting lower anionic redox activity of the shell is key to improve the electrochemical performance. With the aid of a Couette Taylor Flow Reactor, spherical secondary particles with high tap density and narrow particle size distribution are co-precipitated, leading to a valuable hierarchical morphology with superior electrochemical long-term behavior. Thereby, excellent initial Coulombic efficiencies of 90 – 95 % are attained. Finally, another main focus of this work concentrates on the impact of effective performance-improving shell thickness and, thus, provides further insights into the intrinsic nature of the carbonate-derived integrated LMR-NCM active materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Here we present the readily accessible amino acid 4,5-dimethoxy-2-nitrobenzyl- L -cysteine (DNC), as an ultra-low molecular weight gelator (MW = 316 g mol−1). Sonication of DNC in water or organic solvents as well as pH adjustment in water trigger gelation. A diverse set of stimuli (UV irradiation, oxidation, heat or pH change) induce a gel–sol transition. Moreover, the photo-triggered gel–sol transition was used to obtain a controlled cysteine release from the hydrogel. [ABSTRACT FROM AUTHOR]

Lithium ion battery cells operating at high‐voltage typically suffer from severe capacity fading, known as 'rollover' failure. Here, the beneficial impact of Li2CO3 as an electrolyte additive for state‐of‐the‐art carbonate‐based electrolytes, which significantly improves the cycling performance of NCM523 ∥ graphite full‐cells operated at 4.5 V is elucidated. LIB cells using the electrolyte stored at 20 °C (with or without Li2CO3 additive) suffer from severe capacity decay due to parasitic transition metal (TM) dissolution/deposition and subsequent Li metal dendrite growth on graphite. In contrast, NCM523 ∥ graphite cells using the Li2CO3‐containing electrolyte stored at 40 °C display significantly improved capacity retention. The underlying mechanism is successfully elucidated: The rollover failure is inhibited, as Li2CO3 reacts with LiPF6 at 40 °C to in situ form lithium difluorophosphate, and its decomposition products in turn act as 'scavenging' agents for TMs (Ni and Co), thus preventing TM deposition and Li metal formation on graphite. [ABSTRACT FROM AUTHOR]

Electrode processing and performance strongly depend on the active material. Maximizing the active material content of positive composite electrodes enables low cost and high energy density. However, this maximization cannot reach 100%, as composite electrodes additionally consist of binder to provide mechanical integrity and conductive additive to enhance electronic conductivity, which in combination create a flexible porous microstructure for appropriate electron and lithium transport. In this study, the influence of three positive active material classes, layered oxide LiNi 0.6 Mn 0.2 Co 0.2 O 2 , spinel-type LiMn 2 O 4 and olivine-type carbon-coated LiFePO 4 , were investigated regarding the optimum amount of polyvinylidene difluoride as binder and carbon black as conductive additive to achieve high mechanical stability as well as high electronic and ionic conductivity within composite electrodes. Formulation optimization was conducted and compared to a reference electrode formulation with regard to physical, mechanical, electronic and electrochemical properties. In a first step, the binder amount was optimized for each active material class by varying the ratio of binder content to surface area of the solid electrode components. In a second step, the critical conductive additive content was determined. Overall, this strategy allows to decipher material class dependent optimized electrode formulations for high energy density composite electrodes with maximized active material content. [Display omitted] • Strategy to develop material class dependent electrode formulations. • Active material particle surface and size affects binder and conductive additive amount. • Carbon-coated LiFePO 4 based composite electrodes show a high SOH with low conductive additive content. [ABSTRACT FROM AUTHOR]

The presented case study provides mesoscopic insights into the state-of-charge (SOC) distribution of battery electrodes containing layered transition metal oxides with Li(Ni 0.5 Mn 0.3 Co 0.2)O 2 (NMC532). The application of classification-single-particle inductively coupled plasma optical emission spectroscopy (CL-SP-ICP-OES) enables the rapid screening of the lithium content of individual cathode active material (CAM) particles achieving a statistically viable elucidation of the mesoscale SOC distribution between different particles of the electrode. The results reveal the evolution of a persistent mesoscale SOC heterogeneity of the electrode upon delithiation at slow rates and extensive relaxation times as confirmed by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The implications of local chemical and structural ramifications of the investigated NMC532 for heterogeneous active material utilization are thoroughly discussed. Furthermore, it is found that the evolved SOC heterogeneity of the electrode is strongly dependent on the current density. The correlation to the decreased capacity utilization is further investigated with a straightforward quantification approach revealing a considerable contribution to capacity fading by persistently inactive lithium in the CAM. The results highlight the importance of the analysis of persistent mesoscale SOC heterogeneity as a potential capacity fade mechanism in layered lithium transition metal oxide-based battery electrodes. [Display omitted] • Lithium ion batteries. • Lithium transition metal oxides. • State-of-charge heterogeneity. • Single particle analysis. • Aging mechanisms. [ABSTRACT FROM AUTHOR]

Graphite Lithium-Ion Cells: On the Beneficial Impact of Li2CO3 as Electrolyte Additive in NCM523 Graphite Lithium Ion Cells Under High-Voltage Conditions (Adv. Lithium carbonate, lithium difluorophosphate, lithium ion cells, lithium metal plating, rollover failure, electrolyte additives Keywords: electrolyte additives; lithium carbonate; lithium difluorophosphate; lithium ion cells; lithium metal plating; rollover failure EN electrolyte additives lithium carbonate lithium difluorophosphate lithium ion cells lithium metal plating rollover failure 1 1 1 03/13/21 20210311 NES 210311 In article number 2003756, Martin Winter, Tobias Placke, and co-workers address challenges related to the high-voltage operation of NCM523 graphite lithium-ion cells, suffering from transition metal (TM) dissolution/deposition, which subsequently induces capacity fading. [Extracted from the article]