Part II of the SodiumFrostGlow Technology Trilogy – Power & Control
In electrochemistry, a cell’s operating-voltage window sets the hard ceiling on usable energy. Lithium-ion batteries are normally cut off at ≈2.8 V; below that their chemistry becomes unstable. Sodium-ion cells, however, reveal a huge material-science advantage: they remain structurally sound and continue delivering energy down to 2.0 V.
The band from 2.8 V to 2.0 V is a “no-man’s-land” for lithium, yet it holds roughly 10 % extra capacity for sodium. The energy is real; no commercial solution has ever extracted it safely and efficiently. One of SodiumFrostGlow’s core missions is to forge the key that unlocks this hidden range. That demands three unprecedented power-electronics challenges.
Challenge 1 – Hearing a millivolt signal through circuit noise
At 2.0 V the cell is hypersensitive: tiny changes in internal resistance or temperature create millivolt-level ripples. These cues are easily drowned by EMI from nearby switches. Ordinary BMS front-ends lack the resolution and speed to decide what is a genuine distress call and what is junk. Premature shutdown wastes energy; late shutdown hurts the cell.
We redesigned the analogue front-end: differential sampling, multi-stage active filtering, ultra-precise voltage references and software noise-rejection algorithms. The result is military-grade noise-cancelling headphones for the BMS—clear heartbeats from every cell even on a noisy battlefield.
Challenge 2 – A high-efficiency boost engine for ultra-low input
An inverter must step low-voltage DC up to AC. Holding power constant, halving the input voltage doubles the input current. At 2.0 V the amperage becomes enormous, generating I²R heat that collapses efficiency or destroys MOSFETs. No commercial topology targets this corner case.
Together with our inverter supplier we are developing a multi-phase interleaved synchronous-boost topology. Current is split into several parallel phases firing like a multi-cylinder engine, cutting stress and heat per switch. Perfect phase synchronisation demands complex control code. When finished we will have the first high-efficiency power-train able to cruise comfortably inside sodium’s lowest-voltage valley.
Challenge 3 – Drawing the first accurate full-voltage discharge map of sodium
Accurate state-of-charge (SOC) is the compass of battery management. Lithium enjoys public databases; sodium from 3.9 V down to 2.0 V has none. We are the first team that must characterise it systematically.
Inside our environmental chambers hundreds of cells cycle thousands of times across temperatures and C-rates, generating massive raw datasets. A mixed-model algorithm (OCV, internal resistance, temperature) turns those data into a proprietary SOC estimator. Every line of code and every plotted point drafts the first precise topographic map for this new energy territory.
Mastering these challenges does more than extend runtime; it converts sodium’s theoretical edge into engineering reality. When that hidden 10 % is released exactly when you need it most, you will feel the value of every hour we invest today.