The design and operation of rechargeable batteries is predicated on orchestrating flows of mass, charge, and energy across multiple interfaces. Understanding such flows requires knowledge of atomistic and mesoscale diffusion pathways and the coupling of ion transport with electron conduction and stress gradients across length scales. Using multiple polymorphs of V<sub>2</sub>O<sub>5</sub> as model systems, I will discuss our efforts to develop an Angstrom-level view of diffusion pathways using a combination of single-crystal X-ray diffraction and density functional theory calculations. Scanning transmission X-ray microscopy and X-ray ptychography imaging in conjunction with phase field modeling provide a means of mapping the accumulative results of atomic scale inhomogeneities at mesoscale dimensions, and further enables tracing of stress gradients across individual particles and electrode architectures. Deciphering the origins of strain modulation of diffusion pathways and intercalation phase diagrams provides a means of improving cyclability and rate performance. The mitigation of diffusion impediments will be discussed with reference to two distinct approaches: (a) utilization of Riemann manifolds as a geometric design principle for electrode architectures and (b) the atomistic design of polymorphs with well-defined diffusion pathways that provide frustrated coordination.  Finally, I will discuss the role of chemical substitution and the extent to which it can be considered a proxy for stress modification of intercalation phase diagrams.

Designing electrode architectures across length scales: Some lessons learned from Li-ion and “beyond Li” chemistries

ACS Spring 2022

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