Microdroplet Templating of Uniform Nanostructured Battery Microparticles with Scalable Membrane Emulsification

TL;DR

A new method creates uniform battery microparticles using droplet templating, improving battery performance and scalability.

Contribution

A scalable membrane emulsification method is introduced for fabricating uniform nanostructured battery microparticles.

Findings

Droplet templated LTO achieved twice the tap density of nanopowder precursors.

LTO/CNT microparticle electrodes showed over 50% higher volumetric energy density than unstructured particles.

The method is compatible with both microfluidic screening and industrial-scale membrane emulsification.

Abstract

The manufacture of
electrodes with controlled, adjustable
nano-
to microscale structures can drastically improve the volumetric energy
density and transport properties of Li-ion batteries. Assembling microscale
secondary particles from nanoparticles is a promising approach, but
existing processing methods either result in nonuniform morphologies
or have an unfeasibly low throughput. This work leverages controlled
emulsification to create uniform battery microparticles from droplet
templates. Issues with emulsion stability, drying, and scale-up are
addressed, which have previously hindered the implementation of emulsion
structuring for battery materials. Here, the templating method is
demonstrated using commercial lithium titanate (LTO) nanopowder. Secondary
LTO particles with controlled diameter, narrow size distributions,
and spherical shape are successfully fabricated. Droplet templated
LTO achieved tap-densities twice that of the nanopowder precursor.
Microparticle electrodes showed improved electrochemical performance
exceeding that of unstructured nanoparticles and of commercial spray-dried
microparticles, particularly at high rates. Furthermore, this approach
is compositionally flexible, illustrated by coassembling carbon nanotubes
and LTO into uniform composite microparticles. LTO/CNT microparticle
electrodes achieved >50% higher volumetric energy densities at
0.1C
than their unstructured counterparts. Finally, the proposed structuring
method is compatible with microfluidic droplet generators, which enable
parameter screening, and industrially viable membrane emulsification,
which facilitates scaled up microparticle production.

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