Polymer-Derived Ceramic Batteries

Common Types: Polysilanes (Si), Polycarbosilanes (SiC), Polysiloxanes (SiO), Polysilazanes (SiN), Polysilylcarbodiimides (SiNC)
Applications: Complex-Shaped Monoliths, Fibers, Coatings, Infiltrated Porous Media and Powders
molecular structure & type of preceramic polymer determine; composition, phase amounts, phase distribution, & microstructure of the final ceramic & chemical and physical properties
Synthesis: Sol–Gel (for SiOC-based materials), Non-Oxidic Sol–Gel (for SiCN- and SiBCN-based materials), Polysilylcarbodiimide Gels
Requirements for Effective Preceramic Polymers: High Molecular Weight (to prevent the volatilization of low-molecular-weight components during thermal decomposition), Rheological Properties and Solubility (for shaping purposes), Latent Reactivity (presence of functional groups)
Polymer-to-Ceramic: 1) Synthesis of Preceramic Polymers from monomers, 2) Crosslinking at Low Temperatures for formation of infusible organic/inorganic networks (100-400), 3) Ceramization via Pyrolysis (between 1000°C to 1400°C, amorphous), higher temperatures --> lead to (poly)crystalline materials
oxygen curing (for cross linking) of polysilanes: in the presence of Oxygen, Si-H and Si-CH3 to Si-OH and Si-O-Si and C=O --> after pyrolysis it gives high oxygen SiC
electron-beam curing: Si-H and Si-CH3 to Si–CH2–Si --> low oxygen content
ceramization of Polycarbosilanes: 550-800--> transform to inorganic (no H-C bond), 800-1000--> SiC-based material
ceramization of Polysiloxanes: convert into amorphous silicon oxycarbide (SiOC) and residual free carbon, evolution of hydrocarbons (mainly CH4) and hydrogen
Challenges: shrinkage and residual porosity based on the precursor
fillers--> minimize shrinkage--> less residual stress and porosity, two filler types: 1) Passive: do not react during pyrolysis, Al2O3, SiO2, Y2O3, SiC, B4C, Si3N4, BN 2) active: react (pure metals, intermetallics, metal hydrides, or metal carbonyl complexes)
SiOC ceramics
- amorphous-->Tetrahedral units: SiC4, SiC3O, SiC2O2, and SiO4
- sp3 carbon--> bond to silicon (means it has 4 single bonds), sp2 carbon-->segregated or free carbon
- Small silica-rich nanodomains (1–3 nm in size)--> incorporated into graphene-like cellular network
- Domain walls: graphene and mixed-bond tetrahedra, with silicon bonded to both carbon and oxygen.
- amorphous up to 1300–1350°C
- beyond 1300: phase separation--> silica, silicon carbide, and excess carbon
- higher temp: Crystallization of phase-separated silicon carbide & Carbothermal reaction of phase-separated silica with excess carbon, forming crystalline SiC and releasing gaseous CO.
- Beyond 1500°C: silica + SiC --> silicon monoxide & CO--> decomposition of SiOC ceramics; fine crystallites of silicon carbide and graphite-like carbon
- SiOC + boron --> SiBOC --> crystallization of silicon carbide at lower temperatures
SiCN ceramics
- from 1) pyrolysis of polysilazanes; single SiCN amorphous phase (silicon atoms tetrahedrally coordinated by carbon and nitrogen) and free carbon, 2) polyorganosilylcarbodiimides consist of separated amorphous silicon nitride and carbon phases
- Si units: SiCNX2, SiCN2X, SiCN3, and SiNX3 sites (X = NCN, NCHN)
- Between 600 and 1000°C, further decomposition of NCN units-->formation of amorphous Si3N4 regions and graphite-like domains
- Nanodomains in SiCN materials --> ranging from 1 to 3 nm, increasing with annealing temperature
- SiCN +boron: higher thermal stability and crystallization resistance; amorphous up to 1700°C and no decomposition up to 2000°C
- Two crystalline phases: SiC2N4 and Si2CN4
excess carbon: lower temperatures --> homogeneously dispersed in the amorphous material; Above 1000°C-->either basic structural units or locally enriched regions of turbostratic graphite
Polysilazane-derived SiCN: compositions of ternary phase equilibrium SiC–Si3N4–C
+1484 degree: reaction of silicon nitride with carbon --> silicon carbide and nitrogen gas
suitable precursors-->compositions without excess carbon-->thermal stability (we have thermal decomposition of silicon nitride at beyond 1841°C)
higher free carbon--> higher oxidation rate
Electrical conductivity: Si–O–C and Si–C–N: between semiconductors (e.g., SiC, graphite) and insulators (e.g., silicon nitride)
pyrolyzed at low temperatures --> insulators--> dc conductivities below 10^-10 V^-1 cm^-1
high carbon content --> semiconducting behavior (Increase in dc conductivity with higher pyrolysis/annealing temperatures and increased free carbon content)
Below 1300°C: amorphous SiOC --> main conductive phase.
Above 1300°C: electron conductivity from segregated free carbon phase.
SiOC/Al2O3 composites with up to 40 vol% alumina--> more rapid phase separation of the SiOC matrix in the presence of Al2O3--> higher free carbon-->higher conductivity
+molybdenum disilicide>higher conductivity
- For SiCN:
- 1000 - 1400°C: Increase in dc conductivity, Proportional to annealing temp (Loss of residual hydrogen and increased sp² content in segregated carbon phase)
- Above 1400°C: increase in conductivity compared to the previous step (Formation of nanocrystalline silicon carbide and reduction in nitrogen content in the SiCN matrix)
- Above 1600°C: Complete crystallization --> 40 wt% Si₃N₄ and 60 wt% SiC, High conductivity (percolation paths formed by the crystalline SiC phase)

Impact of the electrical conductivity on the lithium capacity of polymer-derived silicon oxycarbide (SiOC) ceramics^[1][edit | edit source]

Into:
- polyorganosiloxanes-->thermal conversion in inert atmosphere-->SiOC materials
- SiOC: Si-O-C network, (tetrahedrally coordinated SiO4-xCx units, including SiO2 and C-enriched regions), interpenetrated by an amorphous free carbon
- more than 20% free carbon--> carbon rich
- 3 sites to store the Li ion: 1) interstitial spaces and edges of graphene and carbon layers, 2) micropores, 3) amorphous Si-O-C network
This work:
- Materials and preparation:
- SiOC with different carbon content-->Polyorganosiloxanes RD-684a (PR), RD-688 (SR), RD-212 (RR), polysilsesquioxane PMS MK (MK) --> Mixtures of polymers (SR/RR 50/50 and SR/RR 25/75) and RD-684a modified with divinylbenzene (DVB, PR/DVB 50/50)
- thermal crosslink-->350°C (Heating rates were 50°C/h) for 2 hours-->pyrolysis at 1100°C (100°C/h) for 3 hours under argon
- <40 µm powder size
- Tests:
- Micro-Raman Spectroscopy; Chemical Composition Analysis by Leco-200 carbon analyzer and Leco TC-436 N/O analyzer for carbon and oxygen content (Silicon content calculate by difference to 100 wt.%); SEM; Electrical Conductivity
- Electrode: 85 wt.% SiOC active material, 5 wt.% Carbon Black Super P, and 10 wt.% PVDF binder
- Tape casting: 60 um thickness; 2 mg/cm^2 active material loading
- assembling: reference/ counter electrode: metallic Li, 1 M LiPF6 in EC (1:1) as electrolyte, Whatman glass fiber filter as separator
- Galvanostatic cycling, current rate 37 mA/g, 74 mA/g, and 372 mA/g within the potential range of 0.005–3 V, capacity restoration by 37 mA/g
- Results:
- SiO2, SiC, and free carbon
- All SiOC ceramics at 1100°C are amorphous
- raman: carbon D (1350 cm^-1) and G (1580 cm^-1) bands--> an amorphous carbon phase
- Low free carbon SiOC--> fluorescence tendency
- Carbon-rich samples (PR/DVB 50/50, PR, SR, SR/RR 50/50) --> stable cycling behavior with initial capacities around 500 mAh/g
- Carbon-poor samples (SR/RR 25/75, RR, MK) --> unstable behavior and lower capacities (<100 mAh/g) at higher current rates (372 mA/g) & rapid capacity fading
- carbon rich-->recover higher capacities (~100 mAh/g more) at higher current rates
- higher free carbon, higher electronic and ionic transportation, higher rate capability
- PR/DVB 50/50 --> less stable behavior at high current rates but recovers initial capacity at lower current rates (37 mA/g)
- SEM of PR before and after cycling: particle sizes of 20–25 µm and no significant volume increase or degradation, except for SEI growth
- normalized capacity (set the first cycle lithiation capacity to one for each sample):
  - no significant difference among carbon-rich materials; "sloping-like" insertion
  - RR and MK-->different behavior
    - SEI formation losses (0.6–1.5 V) --> less pronounced
    - insertion plateau at 0.25 V-->reversible lithium storage near oxygen in silica-rich environments (52.9 and 71.6 wt.% SiO2 equivalents--> strong Li-O interaction-->capacity fade
- MK-->highest first insertion capacity; first extraction capacity comparable to other materials
- similar first cycle efficiency (η) close to 60% in Most materials, except MK
- CE in 10 cycle: 100% for carbon rich and 60-80% for low carbon
- CE in 60 cycle: 50 to 70% for carbon rich and 1 to 13% for low carbon
- free carbon phase --> responsible for the reversible storage of lithium ions
- Carbon-poor materials initially recover high capacities (>1000 mAh/g), higher than carbon-rich materials.
- High 10th cycle stabilities (60–80%) --> carbon-poor materials.
- The lower stable capacity in carbon-poor materials: due to the reduced amount of active Li-inserting free carbon & electrical availability of other potential storage sites.
- electrical conductivity of SiOC --> higher with more free carbon content
- electrical conductivity too low to measure for MK (8.1 wt.% free carbon)
  - 2 × 10⁻⁸ S/m for RR (11.6 wt.% free carbon).
  - 2.3 S/m for PR/DVB 50/50 (54.2 wt.% free carbon).
  - conductivity higher than 10⁻² S/m-->Good and stable electrochemical behavior
  - linear dependence of stable reversible capacity (C60delith) on free carbon content
  - Stable extended capacity --> related to the free carbon content
  - conductivity < 3 × 10⁻⁵ S/m, capacity increases slowly & remains below 100 mAh/g
  - Abrupt increase in C60delith up to 250 mAh/g between SR-RR 25/75 and SR-RR 50/50 with conductivity increasing to 10⁻² S/m
  - Further increase in conductivity --> a slight increase in capacity
- Summary:
  - Higher Free Carbon Content:
    - higher electrical conductivity.
    - better accessibility of Li-ion storage sites at high current rates.
  - Lower Free Carbon Content (<20 wt.%):
    - low electrical conductivity.
    - low sufficient electron transport within the SiOC microstructure.
    - lithium ions stored near oxygen in the silica-rich phase.
    - strong Li-O bonds--> high irreversible capacity and low stable capacity.
  - MK and RR: low conductivity; small SEI losses during initial lithium insertion; insulating nature prevents the electrolyte from reacting at the ceramic surface

Lithium insertion into dense and porous carbon-rich polymer-derived SiOC ceramics^[2][edit | edit source]

Intro:
SiOC-->above 600 mAh g^-1
this work: impact of porosity on the electrochemical behavior of SiOC
Affecting factors: Chemical composition of the preceramic polymer & Pyrolysis temp
Porous SiOC: by HF etching of the silica phase within dense SiOC--> promoted by pyrolyzing SiOC at 1400°C --> more phase separation in the SiOC network
highest Li capacities --> at lower pyrolysis temperatures (1000°C – 1100°C)
materials: linear polyhydridomethylsiloxane (PHMS) with a molecular weight of 1900; Platinum divinyltetramethyldisiloxane at 5 ppm relative to the Si compound as catalyst; Divinylbenzene (DVB) in amounts of 10 and 200 wt% based on the siloxane weight
Preparation: mix Catalyst and DVB; add to siloxane; overnight at room; in Ar atmosphere furnace flowing at 150 mL/min with Heating rate 5°C/min at 1400°C for one hour; mortar and pestle < 80 µm-->result: SiOC-X (X the amount of DVB used (10, 200)); 0.5 g of the powdered sample etch with 20 vol% HF solution in water; stirred at room temperature for 6 hours; Filtered and rinsed with distilled water to remove residual HF; oven at 100°C for one day--> result: SiOC-X–HF (10, 200)
Test: XRD (wavelength of 4.562 nm); Raman; NMR; N2 adsorption; HR-TEM; Specific Surface Area (BET); Pore Size Distribution (from adsorption branch of isotherm using BJH)
Electrode (cell assembly):
- SiOC-10, SiOC-200, SiOC-10–HF, and SiOC-200–HF.
- Polyvinylidene fluoride (PVdF, SOLEF) solution in N-methyl-2-pyrrolidone (NMP, BASF).
- Carbonaceous material/PVdF = 9:1
- NMP:0.8 g solvent per 1 g solution
- 10 µm thickness
- Dried at 80°C for 24 hours
- 6-8 mg/cm² active material loading
- 10 mm diameter electrode
- 90°C for 48 hours (post drying)
- Counter/reference electrode: Lithium foil
- electrolyte: 1 M LiPF₆ in ethylene carbonate (EC) and dimethyl carbonate (DMC) in 1:1 weight ratio
- Separator: Celgard 2500
- Cut-off voltages: 0 and 3 V for galvanostatic charges
- Constant voltage float applied at cut-off voltage for slow charging regime (18 mA g⁻¹)
Results:
chemical composition: moreDVB--> more carbon content; HF-->dissolve SiO2--> less oxygen in HF washed; o.3 moles SiC & 0.7 moles SiO2
XRD:
- before HF: 2 theta = 6.4 amorphous SiO2; 2 theta = 10.4 alpha SiC
- after HF: lower amorphous silica peak at 2θ = 6.4°; graphite (0 0 2) plane at 2θ = 7.1°; more intensity of (1 0 1) planes of graphite at 2θ = 12.5°; α-SiC peaks more evident, (higher intensity at 2θ = 10.4°); New peak at 2θ = 5.4° (d = 4.86 Å) (F-intercalated graphite formation)
Raman:
- before etch: Two main bands: D band at ∼1340 cm⁻¹ & G band at ∼1600 cm⁻¹; higher D/G compared to etched samples-->nanocrystalline form and higher structural disorder
- after etch: narrowing of the G band; increased structural order of graphitic carbon
N2 adsorption:
- higher Specific surface area with increasing DVB
pore size:
- Average pore size is 2.5 nm
- Non-etched SiOC-10 and SiOC-200 samples --> no measurable porosity
electrochemical properties:
- before etching:
  - SiOC-10: initial charge capacity of 380 mAh/g; 102 mAh/g discharge; ithium insertion below 0.1 V with a quasi-plateau near lithium plating; extraction starts around 0.5 V
  - SiOC-200: initial charge capacity of 611 mAh/g; 241 mAh/g discharge; starts lithium insertion at about 0.7 V
  - lack of porosity--> Minimal SEI formation -->small capacity losses.
- after etching (electroactivity starting at higher potentials (around 1 V for SiOC-10-HF and 2 V for SiOC-200-HF) due to porous structure and pronounced SEI formation-->Significant hysteresis and capacity losses)
  - SiOC-10-HF: Charge capacity of 457 mAh/g; discharge at 272 mAh/g
  - SiOC-200-HF: Charge capacity of 648 mAh/g; discharge at 268 mAh/g.
- Initial cycles at 18 mAg−1, increased to 36 mAg−1 after 10 cycles--> stable cycling behavior --> potential for practical battery applications--> stability and reversibility
- First charge capacity: higher than graphite; but first cycle --> high irreversibility (due to the formation of non-reversible structures like Li2O3 & SEI)
- high Oxygen content in SiOC--> high irreversible capacity & high hysteresis (excessive oxygen--> li ion trap during first insertion)
- dense structure--> higher Oxygen--> lower efficiency
- two storage sites for Lithium ion: 1)in mixed Si-C-O tetrahedra active sites (the least effect), 2) interstitial spaces or edges between graphene layers
- free carbon phase-->Reversible capacity during the first discharge
- Free carbon in SiOC ceramics--> can store double the amount of lithium compared to commercial graphite.
  - Up to 723 mAh g^-1 for SiOC (LiC3) vs. 371 mAh g^-1 for graphite (LiC6)
  - HF --> dissolves silica --> residual stresses / intercalate F atoms into graphene layers.
  - Structural modifications from etching --> influence lithium storage.
  - High-C SiOC (SiOC-200) more affected by etching than low-C SiOC (SiOC-10)
- better cycling performance in porous SiOC:
  - Porous structure: less stiff and more compliant.
  - Dense SiOC: high modulus matrix of Si-O and Si-C bonds--> constraining carbon nanocrystal expansion/contraction.
  - Porous structure tolerates stress cracking --> better cycling stability.

New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics^[3][edit | edit source]

previous works: SiCN reversible capacities 560 mAh·g^-1; suffered capacity fading
Low carbon materials --> low cycling stability for SiOC and SiCN
lithium insertion into amorphous silica (a-SiO2) and SiOC without free carbon --> energetically unfavorable (large gap between the valence and conduction band)
Si–N bonds --> more covalent than Si–O bonds due to lower electronegativity of nitrogen (3.0) compared to oxygen (3.5); More covalent Si–N bonds -->more localized electron densities, preventing dipole induction in Li atoms
Si–O bonds ionic character in SiOC network--> strongly attracts lithium--> high initial lithiation capacities even with low carbon content.
With cycling, lithium irreversibly captured within the carbon-poor SiOC network--> reducing electrochemical stability.
Replacement of oxygen with nitrogen in the ceramic network --> less attractive for lithium ions.
summary:
- amount of free carbon phase --> not impact the first cycle lithiation and delithiation capacities of SiOC.
- SiCN: more capacity with the amount of carbon until a threshold; about 50% of carbon
- Cycling stability--> low for carbon-poor ceramics in both SiOC and SiCN

Page data
Authors	Maryam Mottaghi
License	CC-BY-SA-4.0
Language	English (en)
Related	0 subpages, 1 pages link here
Impact	page views
Created	June 20, 2024 by 72.139.192.145
Modified	June 28, 2024 by StandardWikitext bot
Cite as	Maryam Mottaghi (2024). "Polymer-Derived Ceramic Batteries". Appropedia. Retrieved July 21, 2024.
API queries	basic, semantic, html, files, more

[1] Impact of the electrical conductivity on the lithium capacity of polymer-derived silicon oxycarbide (SiOC) ceramics

[2] Lithium insertion into dense and porous carbon-rich polymer-derived SiOC ceramics

[3] New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics

[1]

[2]

[3]

Polymer-Derived Ceramic Batteries

Impact of the electrical conductivity on the lithium capacity of polymer-derived silicon oxycarbide (SiOC) ceramics[1][edit | edit source]

Lithium insertion into dense and porous carbon-rich polymer-derived SiOC ceramics[2][edit | edit source]

New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics[3][edit | edit source]

Impact of the electrical conductivity on the lithium capacity of polymer-derived silicon oxycarbide (SiOC) ceramics^[1][edit | edit source]

Lithium insertion into dense and porous carbon-rich polymer-derived SiOC ceramics^[2][edit | edit source]

New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics^[3][edit | edit source]