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'Interfaces: Si-based Electrodes – Polymer & Oxide Electrolytes' (10 pages)
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Lithium-ion batteries – electrolytes – solid & semi-solid
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An interlayer (facing the Li metal electrode and the oxide solid electrolyte layer) containing sulfonic acid groups,
a three-dimensional nanofiber framework and
crosslinked polymers was developed.
The nanofibers were electrospun from a solution containing poly(vinylidene fluoride-co-
hexafluoropropylene) (PVDF-HFP) and D(+)-10-camphorsulfonic acid (DCA, 1.0 mass%) in N,N-
dimethylformamide (DMF). The
resulting interlayer exhibits an uncompressed thickness of ≈40 μm, a compressed thickness of ≈10
μm, and an ionic conductivity of
7.5 × 10-4 S/cm at 25°C.
A monomer reaction mixture containing vinyl carbonate (VEC), fluoroethylene carbonate (FEC),
and lithium
bis(trifluoromethanesulfonyl)imide (LiTFSI) was prepared. Upon thermal curing (70°C), a
crosslinked polymer network formed within the framework pores.
Full cells assembled with lithium metal negative
electrodes and NMC-based positive electrodes (21 mg/cm2 loading) exhibit
88% capacity retention after 50 cycles (0.45 mA/cm2 charge/discharge), while cells
without interlayer failed in the 2nd cycle due to short circuits.
The top Figure shows the schematic of interlayer integration where the composite precursor layer
(1211) can penetrate pores (1203) in the solid electrolyte (14).
The middle Figure illustrates critical current density testing reaching 4.0 mA/cm2,
as compared to 0.9 mA/cm2 for cells without interlayer.
The bottom Figure reveals the porous morphology of the etched (1 M HCl) solid electrolyte surface with a ≈13 μm
deep porous layer.
12: lithium metal electrode
14: solid electrolyte (HCl-etched Li6.5La3Zr1.5Ta0.5O12 / Li2WO4
(LWO) = 100:2 mass ratio)
18: three-dimensional polymer framework
20: electrospun polymer nanofibers
24: pores
122: interlayer components
1203: pores in solid electrolyte
1211: interlayer
This work illustrates how an interlayer based on nanofibers obtained through electrospinning infused with thermally polymerized VEC / FEC
can substantially improve electrochemical characteristics of lithium metal battery cells.
It will be very interesting to see whether the overall electrolyte film thickness can be further reduced.
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The premium version includes another two patent discussions, plus an Excel list with 50-100 commercially relevant recent patent families.
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Lithium-ion batteries – negative electrode (excluding Li metal electrodes)
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A silicon-carbon composite material with a core-shell structure was prepared. The material consists of a carbon-coated silicon-carbon core,
a coupling agent layer, and a conductive carbon layer from inside out. The coupling agent layer connects to the silicon-carbon
composite surface through hydrogen bonding, while the conductive carbon layer connects to the coupling agent layer through
electrostatic interactions.
The silicon-carbon
core consists of silicon (50 mass%), porous carbon (47 mass%), and a carbon coating layer
(3 mass%) on the porous carbon surface.
The coupling agent layer contains 3-aminopropyltrimethoxysilane (APTMS). The conductive carbon layer
contains single-walled carbon nanotubes (SWCNT).
For preparation, porous carbon was placed in a fluidized bed reactor under nitrogen (flow rate 40 L/min). Upon heating to 500°C,
monosilane was introduced (flow rate 10 L/min). The temperature was raised to 550°C and maintained for 6.5 h. After reaction
completion, acetylene gas was introduced (flow rate 10 L/min) for CVD carbon coating.
The Si-carbon material was mixed with 1 mass% APTMS in ethanol solution (stirring at 500 rpm, 30 min), followed by rotary evaporation.
The intermediate material was dissolved in ethanol, mixed with SWCNT (0.5 mass% relative to Si-carbon), stirred (500 r/min, 30 min),
and rotary evaporated to obtain the final composite.
In half-cells, the material exhibits a first discharge capacity of 1,813.1 mAh/g, a first
cycle efficiency of 91.3%, and capacity retention of 90.9% after 400 cycles (0.1 A/g
charge/discharge), as compared to 1,834.5 mAh/g, 90.5%, 80.6% for a comparative material without coupling agent treatment.
The electrode expansion rate remained at 100% after a discharge-charge-discharge sequence, compared to 135% for the
comparative material without coupling agent treatment.
This work illustrates that functionalization of Si-carbon composite materials prepared through monosilane CVD deposition
with a coupling agent layer and SWCNT lead to improved cycling stability, because of reduced volume changes upon cycling.
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Lithium-ion batteries – positive electrode
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A hydroxide precursor with composition Ni0.98Co0.01Mn0.01(OH)2
(D50: ≈4 μm) was mixed with LiOH · H2O (1.02 equivalents), ZrO2 (0.15 equivalents), Al(OH)3 (0.48 equivalents), and
Y2O3 (0.11 equivalents). The mixture underwent a two-step heat treatment in a box
furnace under oxygen (850°C, 4 h, followed by 730°C, 9 h). The
resulting material was pulverized using a rotor mill.
The single-crystal material was mixed with Co(OH)2 (2 mass% with respect to base material) and
Al(OH)3 (0.14 mass% with respect to base material), followed by a heat treatment (640°C, 6 h, oxygen).
The material exhibits a discharge capacity of 208.1 mAh/g and a first
cycle efficiency of 85.9%.
Full cells with graphite negative electrodes exhibit a capacity retention of 90.9%
after 50 cycles (45°C, 0.5 C charge / 1.0 C discharge).
This work illustrates that Posco Future M is pursuing a Ni-rich layered oxide material with 98% Ni content in the core,
with a Zr / Y-enriched layer near the surface and a Co / Al-rich surface layer.
The heat-treatment procedure presumably was
extensively optimized to obtain the right extent of Zr / Y-distribution near the surface.
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Fuel cells (PEMFC / SOFC / PAFC / AEMFC) – electrochemically active materials
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A gas diffusion layer preparation with superior crack resistance was developed:
A porous electrode substrate was prepared dispersing PAN (polyacrylonitrile)-based carbon fibers (average fiber diameter: 7
μm, average length: 3 mm) and acrylic fibers (grades D122 and Bonnell M.V.P.-C651, Mitsubishi Chemical, average length: 3 mm)
in water (1 mass%), followed by treatment with a PTFE (polytetrafluoroethylene, 31-JR, Mitsui-Chemours) / polyoxyethylene (10)
octylphenyl ether surfactant-based water-repellent.
The coating formulation (Example 2) was prepared by mixing acetylene black (Denka Black,
average particle size: 35 nm) with pyrolytic graphite (PC-H, Ito Graphite Industries, average
particle size: 7.7 μm, 100 : 27 by mass), and
PTFE dispersion was added (42 mass% vs. carbon).
The coating liquid was applied using a bar coater to one side of the substrate prepared above,
dried (150°C, 5 min), then sintered (360°C, 30 min) to form a coating layer (34 μm thickness).
The optimized formulation exhibits favorable structural integrity as shown in the Figure (b), with
minimal cracking compared to the comparative example (f). Peel strength measurements
confirm superior adhesion (1.22 N/15mm vs 1.12 N/15mm for the comparative example).
This work illustrates that a conductive carbon network based on acetylene black and pyrolytic carbon in the PEMFC catalyst layer
leads to reduced crack formation and favorable adhesion.
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The premium version includes another two patent discussions, plus an Excel list with 50-100 commercially relevant recent patent families.
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Triweekly patent lists for other categories (Excel files are included for premium users)
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- Lithium metal batteries (excluding Li-S, Li-Air): XLSX
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- Lithium-ion batteries – electrolytes – liquid: XLSX
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- Lithium-ion batteries – separators: XLSX
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- Lithium-sulfur batteries: XLSX
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- Metal-air batteries: XLSX
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- Na-ion batteries: XLSX
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Prior patent updates
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2025-01-14
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2024-12-23
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2024-12-03
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2024-11-12
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2024-10-22
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