Balancing
interfacial stability and Li+ transfer kinetics
through surface engineering is a key challenge in developing high-performance
battery materials. Although conformal coating enabled by atomic layer
deposition (ALD) has shown great promise in controlling impedance
increase upon cycling by minimizing side reactions at the electrode–electrolyte
interface, the coating layer itself usually exhibits poor Li+ conductivity and impedes surface charge transfer. In this work,
we have shown that by carefully controlling postannealing temperature
of an ultrathin ZrO2 film prepared by ALD, Zr4+ surface doping could be achieved for Ni-rich layered oxides to accelerate
the charge transfer yet provide sufficient protection. Using single-crystal
LiNi0.6Mn0.2Co0.2O2 as
a model material, we have shown that surface Zr4+ doping
combined with ZrO2 coating can enhance both the cycle performance
and rate capability during high-voltage operation. Surface doping
via controllable postannealing of ALD surface coating layer reveals
an attractive path toward developing stable and Li+-conductive
interfaces for single-crystal battery materials.
Hexagonal boron nitride (h-BN) is
regarded as one of
the most efficient
catalysts for oxidative dehydrogenation of propane (ODHP) with high
olefin selectivity and productivity. However, the loss of the boron
component under a high concentration of water vapor and high temperature
seriously hinders its further development. How to make h-BN a stable
ODHP catalyst is one of the biggest scientific challenges at present.
Herein, we construct h-BN⊃xIn2O3 composite catalysts through the atomic layer deposition (ALD)
process. After high-temperature treatment in ODHP reaction conditions,
the In2O3 nanoparticles (NPs) are dispersed
on the edge of h-BN and observed to be encapsulated by ultrathin boron
oxide (BO
x
) overlayer. A novel strong
metal oxide–support interaction (SMOSI) effect between In2O3 NPs and h-BN is observed for the first time.
The material characterization reveals that the SMOSI not only improves
the interlayer force between h-BN layers with a pinning model but
also reduces the affinity of the B–N bond toward O• for inhibiting oxidative cutting of h-BN into fragments at a high
temperature and water-rich environment. With the pinning effect of
the SMOSI, the catalytic stability of h-BN⊃70In2O3 has been extended nearly five times than that of pristine
h-BN, and the intrinsic olefin selectivity/productivity of h-BN is
well maintained.
Thin
films with effective ion sieving ability are highly desired
in energy storage and conversion devices, including batteries and
fuel cells. However, it remains challenging to design and fabricate
cost-effective and easy-to-process ultrathin films for this purpose.
Here, we report a 300 nm-thick functional layer based on porous organic
cages (POCs), a new class of porous molecular materials, for fast
and selective ion transport. This solution processable material allows
for the design of thin films with controllable thickness and tunable
porosity by tailoring cage chemistry for selective ion separation.
In the prototype, the functional layer assembled by CC3 can selectively
sieve Li+ ions and efficiently suppress undesired polysulfides
with minimal sacrifice for the system’s total energy density.
Separators modified with POC thin films enable batteries with good
cycle performance and rate capability and offer an attractive path
toward the development of future high-energy-density energy storage
devices.
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