Why Joint Optimization of Composition and Formation Protocol
A battery manufacturer hands us a cell configuration and a performance envelope and asks for a recipe.
We control two things: the electrolyte composition and the formation protocol. Both matter, they interact, and they need to be optimized against each other. This section explains why, in the order a sceptical reader would ask.
The formation step sets the starting point for aging. The protocol decides what actually gets deposited, what gets consumed, and what the cell carries into cycling.
Hardware configuration, performance envelope, and physics calibrations. Form factor, cathode and anode active materials, electrode loading, target conductivity, cycle life, rate capability, operating temperature range, safety thresholds.
Identify harm sources: thermal runaway, gas evolution, dendrite growth, TM dissolution, etc. Propagate each harm through a DAG of causal pathways to rank likely methods of failure. Severity weighting produces per-observable constraint weights.
Candidate pool, multi-phase enrichment, and compatibility screening. 50+ solvents, salts, and additives drawn from a curated molecular database with structural descriptors. Staged derivation of thermodynamic, electrochemical, and interfacial properties filters the design space.
Protocol structure search, 20-KPI evaluation, and global plus local refinement. The formation step sets the SEI thickness, the LiF fraction, the dead-lithium inventory, the porosity, and the HF content.
Capacity loss audit, plating risk assessment, and voltage profile comparison. Predicted formation voltage curves are validated against a physics-based full-cell electrochemical model.
Hardware, constraints, risk, recipe, protocol, and simulation diagnostics. The output is a report the customer can act on directly.
The electrolyte is the single most composition-sensitive layer in a cell. A one percent swing in FEC loading moves the SEI’s LiF content by a large fraction. Swapping from LiPF6 alone to a LiPF6/LiFSI dual-salt blend reshapes transference, shifts the oxidation window, and decides whether the aluminum current collector pits at high voltage.
Between built and cycling sits the formation step, where the cell is charged and discharged under a controlled schedule while the SEI nucleates and grows, gas evolves, lithium is consumed into irreversible products, and both interphases reach steady state.
The obvious workflow is sequential. Pick the best composition first, then find the best protocol for it. If the composition optimizer scores each candidate against the best possible formation outcome that candidate could reach, the sequential workflow lands on the same answer a joint optimization would, while keeping the search space flat.
Initial SEI thickness, product fractions, LiF content, temperature trajectory, salt decomposition, gas generation, dead lithium, mechanical crack state, and initial coulombic efficiency all sit on the protocol side of the line.
Every candidate electrolyte must be evaluated post-formation. A single composition has many possible protocols, and the optimizer needs a fast mapping from composition to the best protocol, not a minute-scale optimal control solve for each candidate.
Instead of solving for the best protocol inside the optimization loop, Lithiox learns the mapping from composition to protocol offline and calls it at composition time. The result is a composition-time call that returns a full formation protocol in milliseconds instead of minutes.
lithiox.com 