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Dixit, Marm B.

Publications and source records attributed to Dixit, Marm B..

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Polymorphism of garnet solid electrolytes and its implications for grain-level chemo-mechanics

Understanding and mitigating filament formation, short-circuit and solid electrolyte fracture is necessary for advanced all-solid-state batteries. Here, we employ a coupled far-field high-energy diffraction microscopy and tomography approach for assessing the chemo-mechanical behaviour for dense, polycrystalline garnet (Li 7 La 3 Zr 2 O 12 ) solid electrolytes with grain-level resolution. In situ monitoring of grain-level stress responses reveals that the failure mechanism is stochastic and affected by local microstructural heterogeneity. In this work, coupling high-energy X-ray diffraction and far-field high-energy diffraction microscopy measurements reveals the presence of phase heterogeneity that can alter local chemo-mechanics within the bulk solid electrolyte. These local regions are proposed to be regions with the presence of a cubic polymorph of LLZO, potentially arising from local dopant concentration variation. The coupled tomography and FF-HEDM experiments are combined with transport and mechanics modelling to illustrate the degradation of polycrystalline garnet solid electrolytes. The results showcase the pathways for processing high-performing solid-state batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Hydrothermal synthesis of Co-free NMA cathodes for high performance Li-ion batteries

Scalable and sustainable production of high voltage cathodes is required to meet the increasing demands for Li-ion batteries. Additionally, the anticipated scarcity of critical materials like cobalt necessitates demonstration of Co-free alternatives that can match the performance metrics of conventional cathodes. Herein, a hydrothermal synthesis route for production of a new class of high-capacity, cobalt-free cathode material, LiNi 0.9 Mn 0.05 Al 0.05 O 2 (NMA9055) for next-generation Li-ion batteries is reported. In this work, the synthesized cathode material shows high crystallinity and purity with monodispersed spherical morphology. Extensive electrochemical, structural, and post-mortem characterization of this novel NMA material is carried out. NMA-Li half cells show an initial discharge capacity of 200 mAh/g with a 96% capacity retention over 100 cycles when cycled between 3.0 and 4.4 V. On the other hand, NMA full cells with Li 4 Ti 5 O 12 (LTO) electrodes as the anode, show an initial discharge capacity of 186 mAh/g with 81% capacity retention over 200 cycles. Post-mortem structural and morphological characterization show that the NMA morphology and crystal structure do not degrade significantly over 200 charge/discharge cycles. This new class of cobalt free cathode material containing nickel, manganese and aluminum synthesized by an ammonia-free synthesis route is expected to provide a facile solution towards sustainable cathode production.

25 ENERGY STORAGE↗
DOE OSTI2022

Understanding slurry formulations to guide solution-processing of solid electrolytes

Scalable processing of thin solid electrolytes is crucial for engineering solid-state batteries with practical energy densities. To leverage existing battery production infrastructure, pathways for solution processing of solid electrolyte films must be investigated. Here, roll-to-roll compatible film preparation of aluminum-doped lithium lanthanum zirconate oxide was studied. Four slurry configurations accounting for different solvent properties and solid loadings were evaluated to investigate the ternary interactions within the dispersions. Rheological and coating stability analyses were carried out on the processed slurries. The analysis and characterization indicated that improved component interactions within the ethanol/toluene system result in homogenized distribution of the particles, binder, and plasticizer, and enable the extraction of free-standing thin films with thicknesses of 20 μm and large area (>15 in. 2 ). The drawbacks and opportunities of several protocols for high temperature sintering of the dried green films were investigated. This study highlights the importance of engineering dispersions during the development of processing protocols for solid electrolytes and provides guidelines for the best practices that can be leveraged for solution processing–based fabrications for a wide range of solid electrolyte materials.

25 ENERGY STORAGE↗