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The widespread use of high‐capacity Ni‐rich layered oxides such as LiNi0.8Mn0.1Co0.1O2 (NMC811), in lithium‐ion batteries is hindered due to practical capacity loss and reduced working voltage during operation. Aging leads to defective NMC811 particles, affecting electrochemical performance. Surface modification offers a promising approach to improve cycle life. Here, we introduce an amorphous lithium titanate (LTO) coating via atomic layer deposition (ALD), not only covering NMC811 surfaces but also penetrating cavities and grain boundaries. As NMC811 electrodes suffer from low structural stability during charge and discharge, We combined electrochemistry, operando X‐ray diffraction (XRD), and dilatometry to understand structural changes and the coating protective effects. XRD reveals significant structural evolution during delithiation for uncoated NMC811. The highly reversible phase change in coated NMC811 highlights enhanced bulk structure stability. The LTO coating retards NMC811 degradation, boosting capacity retention from 86 % to 93 % after 140 cycles. This study underscores the importance of grain boundary engineering for Ni‐rich layered oxide electrode stability and the interplay of chemical and mechanical factors in battery aging. [ABSTRACT FROM AUTHOR]

Next‐generation Li‐ion batteries are expected to exhibit superior energy and power density, along with extended cycle life. Ni‐rich high‐capacity layered nickel manganese cobalt oxide electrode materials (NMC) hold promise in achieving these objectives, despite facing challenges such as capacity fade due to various degradation modes. Crack formation within NMC‐based cathode secondary particles, leading to parasitic reactions and the formation of inactive crystal structures, is a critical degradation mechanism. Mechanical and chemical degradation further deteriorate capacity and lifetime. To mitigate these issues, an artificial cathode electrolyte interphase can be applied to the active material before battery cycling. While atomic layer deposition (ALD) has been extensively explored for active material coatings, molecular layer deposition (MLD) offers a complementary approach. When combined with ALD, MLD enables the deposition of flexible hybrid coatings that can accommodate electrode material volume changes during battery operation. This study focuses on depositing TiO2‐titanium terephthalate thin films on a LiNi0.8Mn0.1Co0.1O2 electrode via ALD‐MLD. The electrochemical evaluation demonstrates favorable lithium‐ion kinetics and reduced electrolyte decomposition. Overall, the films deposited through ALD‐MLD exhibit promising features as flexible and protective coatings for high‐energy lithium‐ion battery electrodes, offering potential contributions to the enhancement of advanced battery technologies and supporting the growth of the EV and stationary battery industries. [ABSTRACT FROM AUTHOR]

Intensive cyanidation of a refractory gold concentrate was studied experimentally and by mathematical modelling. Experiments were carried out in stirred tank reactors at different conditions varying oxygen and cyanide concentrations. Samples taken from the reactor were analyzed for gold and other compounds using fire assay AAS and ICP methods, respectively. Based on the experimental results, kinetic models were developed for gold leaching and for cyanide consumption. In the kinetic models, the effects of dissolved oxygen concentration, free cyanide concentration, amount of leachable gold in the concentrate and solid-liquid mass transfer were taken into account. Kinetic parameters were estimated by fitting the models to the experimental data. The obtained results show good agreement between the measured and predicted concentrations. The reliability of the estimated parameters was studied using Markov chain Monte Carlo methods. All experimental parameters were found to be well-identified. The rate controlling step was determined by comparing the surface reaction and mass transfer limited models. Based on the obtained results, it was concluded that the leaching rate is limited by surface reaction rate. [ABSTRACT FROM AUTHOR]

LiNi0.8Mn0.1Co0.1O2 (NMC811) is one of the most promising cathode materials for high energy density Li-ion batteries (LiBs). However, NMC811 suffers from capacity fading during electrochemical cycling because of its structure instability at voltages > 4.2 V vs Li|Li+ due to the known hexagonal H2 → H3 phase transition. Zr doping has proven to be effective in enhancing electrochemical performances of the NMC811. In depth investigations are conducted through operando x-ray diffraction (XRD) and ex-situ x-ray absorption spectroscopy (XAS) measurements to mechanistically understand the benefits of Zr-doping in a NMC811 material when doped during the co-precipitation step. Herein, Zr-doping in NMC811 reduces the formation of the detrimental H3 phase and mitigates the transition metal dissolution upon cycling., (© 2024 Wiley‐VCH GmbH.)

The widespread use of high-capacity Ni-rich layered oxides such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811), in lithium-ion batteries is hindered due to practical capacity loss and reduced working voltage during operation. Aging leads to defective NMC811 particles, affecting electrochemical performance. Surface modification offers a promising approach to improve cycle life. Here, we introduce an amorphous lithium titanate (LTO) coating via atomic layer deposition (ALD), not only covering NMC811 surfaces but also penetrating cavities and grain boundaries. As NMC811 electrodes suffer from low structural stability during charge and discharge, We combined electrochemistry, operando X-ray diffraction (XRD), and dilatometry to understand structural changes and the coating protective effects. XRD reveals significant structural evolution during delithiation for uncoated NMC811. The highly reversible phase change in coated NMC811 highlights enhanced bulk structure stability. The LTO coating retards NMC811 degradation, boosting capacity retention from 86 % to 93 % after 140 cycles. This study underscores the importance of grain boundary engineering for Ni-rich layered oxide electrode stability and the interplay of chemical and mechanical factors in battery aging., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

O3-type NaNi 0.8 Mn 0.1 Co 0.1 O 2 (NaNMC811) cathode active materials for sodium-ion batteries (SIBs), with a theoretical high specific capacity (∼ 187 mAh g -1 ), are in the preliminary exploration stage. This study comprehensively investigates NaNMC811 from multiple perspectives. For the first time, the phase evolution ( P 3 ¯ m 1 $P\overline{3}m1$ - F m 3 ¯ m $Fm\overline{3}m$ - R 3 ¯ m $R\overline{3}m$ ) during the solid-state synthesis is systemically investigated, which elucidates in-depth the mechanisms of the thermal sodiation process. Furthermore, an Al-gradient doping of NaNMC811 was successfully implemented through Al 2 O 3 coating on the cathode active material (CAM) precursor. The modified Al-NaNi 0.8 Mn 0.1 Co 0.1 O 2 (Al-NaNMC811) exhibits excellent electrochemical dynamics and performance, maintaining a specific capacity above 100 mAh g -1 after 100 cycles at 0.1 C (1.5-4.1 V) while providing a promising capacity retention of 63%. Additionally, the material demonstrates excellent rate capabilities, retaining a specific capacity of 107 mAh g -1 at 5 C. Compared to pristine NaNMC811, the modified Al-NaNMC811 is proven to have improved electrochemical kinetics with a higher Na + diffusion coefficient due to dilated (003) interplanar spacing, and a more stable structure during the electrochemical charge-discharge processes, which is attributed to stronger Al-O bond energy. Understanding phase formations during the synthesis and comprehensive insight in the gradient doping for O3-type NaNMC811 CAMs guides further development of next-generation SIBs materials., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)