Lithium intercalates in every fourth layer, then every tird, and so on, so the structure has definitive “stages” during the charge process. Will explain volume expansion on different amounts of intercalated lithum (or Potassium)
Image shows perfectly stacked staging, but is probably more complex with cation “dislocations” in the z plane.
Liquid electrolyte stability on anode and cathode materials:
Reducing/Oxidative potential at the anode/cathode side
E-Lyte has potential window much like the E-pH stability window of water
Decomposition are expected, but kinetics can be slow(Good for batterly life)
What makes LIB unsafe, trigger thermal runaway?
Overcharge: O\(_2\) evolution at cathode side, or formation of reactive peroxide. This can oxidize the carbon additive, or the organic electrolyte. Exothermic reactions lead to temp rise, increased kinetics, thermal runaway, pressure rise, rupture.
Li(s) may deposit on anode -> dendritic growth -> internal short -> internal discharge -> resistive heating -> increased kinetics -> electrolyte fire -> thermal runaway -> pressure rise -> explosion. Problem much less problem in Li-ion battery than Li-metal anode batteries.
SEI : Solid elecrolyte interface/interphase
Can stabilize graphite surface, making less anode degradation (exfoliation)
Is made from decomposing electrolyte, be wary of low electrolyte content
Parameters essential to high energy LIBS:
Voltage
Capacity
Power rating? Kinetics at anode, cathode and in electrolyte
Coating
Help with cation dissolution form cathode to e-lyte
100nm-1um: so thin that it dont block lithium transport
Might help with particles breaking off, ex on anode
Ionic liquid electrolyte
Organic or inorganic molecules as anios or cations.
Low T\(_m\) low P\(_{vap}\)
Can help with degradation reactions due to higher stability window
Thermal stability
Replacing liquid electrolyte with SSE:
Remove flamable organic liquid
Reduce excessive SEI formation
Reduce loss of electroactive material
Tolerates higher voltages
Lower thermal runaway risk (both reduce internal short circuit risk and energy available when burning)
Importance of conductive additives
Layered oxides, olivines, or spinels usually dont have high electrical conductance
Other ion-batteries
Potassium, Sodium (slightly less voltage, and harder intercalation in anode)
Mg, Ca
very hard because of size
cant be intercalated in graphite
new anode materials neeeded, conversion/alloying anodes.
Diffusion because of divalency so low! Few candidates
Probably hard to remove cation out of a structure because of strong bonds, and it might also damage the host structure.
