What exactly comes under Side reactions ? (LLI, LAM; concentration balance)

[mlnsai]

Hi Team,

I have run a simple experiment (attached) for 20 cycles, enabling both chemical and mechanical degradation effects (attached options);

option={
"SEI":"solvent-diffusion limited",
"particle mechanics": ("swelling and cracking", "swelling only"),
"particle" : "Fickian diffusion",
"SEI on cracks": "true",
"loss of active material": "stress-driven",
"thermal": "lumped",
"SEI film resistance": "distributed",
"SEI porosity change" : "true",
"lithium plating": "reversible",
}

experiment = pybamm.Experiment(
[(
"Discharge at 1C until 2.7V",
"Charge at 0.5C until 4.2V",
"Hold at 4.2V until 50mA"
)] * 20
)

I am trying to understand the loss of lithium to side reactions in this.

LLI (Chemical degradation)

Loss of lithium to SEI [mol] = 0.000115406
Loss of lithium to lithium plating [mol] = 0.000577182
Total lithium lost from electrolyte [mol] = 0.000331981

LAM (Mechanical degradation)

Loss of active material in positive electrode [mol] = 0.000021151
Loss of active material in negative electrode [mol] = 0.000026540

Total lithium lost to side reactions [mol] is coming up to be = 0.000115406 + 0.000577182 + 0.000331981 + 0.000021151 + 0.000026540 = 0.001072261.

However,

From simulation, Total lithium lost to side reactions[mol] = 0.001140848

Where is that extra loss in the lithium is coming from during simulation ? (0.001140848 - 0.001072261 = 0.00006858727395935 mol )

I understand the total loss of capacity is not a linear relation between LAM and LLI ([https://doi.org/10.1016/j.jpowsour.2019.03.104]). But, I guess conservation of mass should be valid at any instant.

Thanks in advance.