Developing
cost-effective
high-voltage
Ni-rich
cathodes
has
reached
a
consensus
to
replace
conventional
ultrahigh
Ni
counterparts
for
high-energy
Li-ion
batteries,
but
more
rigorous
requirements
are
put
forward
their
mechanical
and
chemical
stability.
Herein,
we
report
the
design
synthesis
of
full
concentration
gradient
LiNi0.75Mn0.20Co0.05O2
cathode
with
Mn-rich
Ni-poor
surface,
which
been
realized
by
in
situ
forming
PO43-
distribution
retard
transition-metal
ions'
interdiffusion
during
high-temperature
lithiation
process.
This
mitigates
stress
at
source
high
morphological
integrity
refrains
lattice
oxygen
loss
under
4.5
V
operation.
After
Li0.1B0.967PO4
is
coated,
surface
parasitic
reactions
further
ameliorated
stable
interface
chemistry.
The
resultant
deliver
reversible
capacity
as
212.6
mAh
g-1
2.7-4.5
an
energy
density
>800
Wh
kg-1cathode,
almost
equivalent
state-of-the-art
Ni-content
90%
2.7-4.3
V.
In
commercial-grade
cells,
superior
cycle
life
80.5%
retention
achieved
1C
within
after
1700
cycles,
exhibiting
promising
opportunities
compositional
cathodes.
Ni-rich
layered
oxide
cathode
materials
are
promising
candidates
for
high-specific-energy
battery
systems
owing
to
their
high
reversible
capacity.
However,
widespread
application
is
still
severely
impeded
by
severe
capacity
loss
upon
long-term
cycling.
It
has
been
proven
that
the
cyclic
stability
of
closely
related
microstructure
and
morphology.
Despite
this,
influence
primary
particles
on
fatigue
mechanism
during
prolonged
cycling
not
fully
understood.
Here,
two
spherical
agglomerate
oxides
consisting
particle
with
different
length/width
ratios
successfully
synthesized.
found
structural
both
strongly
depends
crystallites,
although
there
no
significant
difference
between
electrochemical
crystalline
characteristics
initial
cycle.
A
higher
ratio
could
effectively
inhibit
accumulation
microcracks
chemical
degradation
cycling,
thereby
promoting
performance
(80%
retention
after
200
cycles
at
1
C
compared
55%
counterpart
a
lower
ratio).
This
study
highlights
structure-activity
relationship
mechanisms
advancing
development
materials.
Abstract
Ni‐rich
cathodes
are
more
promising
candidates
to
the
increasing
demand
for
high
capacity
and
ability
operate
at
voltages.
However,
Ni
content
creates
a
trade‐off
between
energy
density
cycling
stability,
mainly
caused
by
chemo‐mechanical
degradation.
Oxygen
evolution,
cation
mixing,
rock
salt
formation,
phase
transition,
crack
formation
contribute
degradation
process.
To
overcome
this
problem,
strategies
such
as
doping,
surface
coating,
core‐shell
structures
have
been
employed.
The
advantage
of
doping
is
engineer
cathode
surface,
structure,
particle
morphology
simultaneously.
This
review
aims
summarize
recent
advances
in
understanding
mechanism
role
different
dopants
enhancing
thermal
stability
overall
electrochemical
performance.
pinning
pillaring
effects
on
suppressing
oxygen
transition
introduced.
It
found
that
higher
ionic
radii
enable
reside
particles,
preserving
refining
suppress
formation.
Finally,
effect
Li
ion
diffusion,
rate
capability,
long‐term
discussed.
Developing
cost-effective
high-voltage
Ni-rich
cathodes
has
reached
a
consensus
to
replace
conventional
ultrahigh
Ni
counterparts
for
high-energy
Li-ion
batteries,
but
more
rigorous
requirements
are
put
forward
their
mechanical
and
chemical
stability.
Herein,
we
report
the
design
synthesis
of
full
concentration
gradient
LiNi0.75Mn0.20Co0.05O2
cathode
with
Mn-rich
Ni-poor
surface,
which
been
realized
by
in
situ
forming
PO43-
distribution
retard
transition-metal
ions'
interdiffusion
during
high-temperature
lithiation
process.
This
mitigates
stress
at
source
high
morphological
integrity
refrains
lattice
oxygen
loss
under
4.5
V
operation.
After
Li0.1B0.967PO4
is
coated,
surface
parasitic
reactions
further
ameliorated
stable
interface
chemistry.
The
resultant
deliver
reversible
capacity
as
212.6
mAh
g-1
2.7-4.5
an
energy
density
>800
Wh
kg-1cathode,
almost
equivalent
state-of-the-art
Ni-content
90%
2.7-4.3
V.
In
commercial-grade
cells,
superior
cycle
life
80.5%
retention
achieved
1C
within
after
1700
cycles,
exhibiting
promising
opportunities
compositional
cathodes.
