Title: Designing and Architecting Battery Electrode Materials across Length Scales
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. Using multiple polymorphs of V2O5 as model systems, I will discuss
our efforts to develop an Ångstrom-level view of diffusion pathways. Topochemical single-crystal-to-single-crystal
transformations provide an atomistic perspective of how diffusion pathways are altered by modification of V—O connectivity, preintercalation,
and high degrees of lithiation. Recently devised multi-step synthetic schemes enable the positioning of Li-ions
across four distinct interstitial sites of a V2O5 insertion host and allow for deterministic redirection of Li-ion flows through
strategic positioning of transition-metal ions.
At higher length scales, scanning transmission X-ray microscopy and ptychography imaging provide a means of mapping the
accumulative results of atomic scale inhomogeneities at mesoscale dimensions and further enable tracing of stress
gradients across individual particles. I will discuss strategies for the mitigation of diffusion impediments and degradation
mechanisms based on controlling the coupling of chemistry, geometry, and mechanics. Some of these strategies include (a)
utilization of Riemannian manifolds as a geometric design principle for electrode architectures; (b) atomistic design of
polymorphs with well-defined diffusion pathways that provide frustrated coordination; and (c) site-selective modification as a
means of tuning lattice incommensurability between lithiated and unlithiated phases.