2 research outputs found
Conducting Polymer-Skinned Electroactive Materials of Lithium-Ion Batteries: Ready for Monocomponent Electrodes without Additional Binders and Conductive Agents
Rapid
growth of mobile and even wearable electronics is in pursuit of high-energy-density
lithium-ion batteries. One simple and facile way to achieve this goal
is the elimination of nonelectroactive components of electrodes such
as binders and conductive agents. Here, we present a new concept of
monocomponent electrodes comprising solely electroactive materials
that are wrapped with an insignificant amount (less than 0.4 wt %)
of conducting polymer (PEDOT:PSS or poly(3,4-ethylenedioxythiophene)
doped with poly(styrenesulfonate)). The PEDOT:PSS as an ultraskinny
surface layer on electroactive materials (LiCoO<sub>2</sub> (LCO)
powders are chosen as a model system to explore feasibility of this
new concept) successfully acts as a kind of binder as well as mixed
(both electrically and ionically) conductive film, playing a key role
in enabling the monocomponent electrode. The electric conductivity
of the monocomponent LCO cathode is controlled by simply varying the
PSS content and also the structural conformation (benzoid-favoring
coil structure and quinoid-favoring linear or extended coil structure)
of PEDOT in the PEDOT:PSS skin. Notably, a substantial increase in
the mass-loading density of the LCO cathode is realized with the PEDOT:PSS
skin without sacrificing electronic/ionic transport pathways. We envisage
that the PEDOT:PSS-skinned electrode strategy opens a scalable and
versatile route for making practically meaningful binder-/conductive
agent-free (monocomponent) electrodes
Activity-Durability Coincidence of Oxygen Evolution Reaction in the Presence of Carbon Corrosion: Case Study of MnCo<sub>2</sub>O<sub>4</sub> Spinel with Carbon Black
Highly oxygen evolution
reaction (OER)-active electrocatalysts
often exhibit improved OER durability in the presence of carbon corrosion
or oxidation (COR) in the literature. The activity-durability coincidence
of OER electrocatalysts was theoretically understood by preferential
depolarization in galvanostatic situations. At constant-current conditions
for a system involving multiple reactions that are independent and
competitive, the overpotential is determined most dominantly by the
most facile reaction so that the most facile reaction is responsible
for a dominant portion of the overall current. Therefore, higher OER
activity improves durability by mitigating the current responsible
for COR. The activity-durability coincidence was then proved experimentally
by comparing between two catalysts of the same chemical identity (MnCo<sub>2</sub>O<sub>4</sub>) in different dimensions (5 and 100 nm in size).
Carbon corrosion responsible for inferior durability was suppressed
in the smaller-dimension catalyst (MnCo<sub>2</sub>O<sub>4</sub> in
5 nm) having more numbers of active sites per a fixed mass