Automotive Engineering - May 2022 - BET14

Solid-State Batteries
12 34
Li+
Li+
Li+
Cathode
Interface
Formation
Solid Electrolyte
Li+
Li+
Alloy
Reaction
Li-Si
Silicon
Li-Si Alloy
Li+
Li+
Expansion &
Densification
Li+
Li+
Micro-Silicon Anode
Cell Charging
The process of the UCSD/LG Energy Solution silicon-anode solid-state battery: 1) The all-solid-state battery consists of a cathode composite
layer, a sulfide solid electrolyte layer, and a carbon free micro-silicon anode. 2) Before charging, discrete micro-scale Silicon particles make up
the energy dense anode. During battery charging, positive Lithium ions move from the cathode to the anode, and a stable 2D interface is
formed. 3) As more Lithium ions move into the anode, it reacts with micro-Silicon to form interconnected Lithium-Silicon alloy (Li-Si) particles.
The reaction continues to propagate throughout the electrode. 4) The reaction causes expansion and densification of the micro-Silicon particles,
forming a dense Li-Si alloy electrode. The mechanical properties of the Li-Si alloy and the solid electrolyte have a crucial role in maintaining
the integrity and contact along the 2D interfacial plane. (Photo: UCSD)
Next-generation lithium-ion battery
Aims
Longer service
Life
Greater energy
density
Evolution in liquid-based battery
materials
Cathode
Discharge
Ion
Anode
Ion
Charge
Electrolyte
New
Prismatic
structure
Laminated
More compact
size
Innovation in liquid battery structure
Lower
cost
All-solid-state batteries
Cathode
Discharge
Ion
Anode
Ion
Solid electrolyte
Charge
of carbon dioxide and maintaining a pure
oxygen atmosphere, could create very
good bonding at temperatures up to 700
degrees - and without forming the undesirable,
resistance-inducing compounds.
The performance of the cathode-electrolyte
interface made using this method,
said professor of nuclear and materials
science and engineering Bilge Yildiz, who
also coauthored the technical paper describing
the
research
in the journal
Toyota's planned progression to solid-state batteries envisions initial solid-state use in hybrid-electric
rather than fully electric vehicles. (Photo: Toyota)
% Retention - 1700 consecutive XFC cycles
10
20
30
40
50
60
70
80
90
100
200 400 600 800 1000 1200 1400 1600
Cycle #
1800 2000
*
*
Retention >70% after 1700
consecutive XFC cycles
No accelerated deterioration even
after 1000 consecutive XFC cycles,
unlike competing technologies
Cell type
Anode
Cathode
Energy Density
Specific energy
Charge Time
Temperature
0-80% 15 min
300 Wh/kg eq
680 Wh/L eq
NMC811
Silicon-dominant
1i 115mAh pouch
25 °C
External Pressure 0 psi
Energy-retention plot for StoreDot's " silicon-dominant " XFC battery cell, the company's interim
step toward a silicon-intensive solid-state battery. (Photo: StoreDot)
14
Advanced Energy Materials, was " comparable
to the best interface resistances we
have seen in the literature, " she told MIT
News. But those favorable resistances
were achieved using the extra step of applying
coatings. " We are finding that you
can avoid that additional fabrication step,
which is typically expensive, " Yildiz added.
The researchers now are analyzing the
durability of these specially sintered bonds
during extended battery cycling. But the new
findings potentially could rapidly be applied
to battery production, Yildiz said. " What we
are proposing is a relatively simple process
in the fabrication of the cells. It doesn't add
much energy penalty to the fabrication " and
the added costs should be negligible.
Toyota, which has its own development
program for solid-state batteries, also is
concerned with the potential for longterm
performance degradation related to
lithium dendrite formation. Toyota Motor
Corp. CTO Masahiko Maeda said in a mid2021
virtually conducted media briefing
attended by SAE Media that in the company's
ongoing solid-state battery research,
" we found that short service life was an
issue. To solve this and other issues, we
Battery & Electrification Technology, May 2022
Retention %
Structure
Composition
Current collector
Separator
Current collector
Current collector
Current collector
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