Performance metrics in batteries are the key quantitative measures used to evaluate how well a battery meets its intended performance goals. These include metrics like capacity (how much charge it holds, usually in mAh or Ah), energy density (Wh/kg or Wh/L), power density (W/kg), internal resistance (which affects power and heat), cycle life (number of cycles until capacity drops to a certain percentage of original), calendar life (how long it lasts in storage or light use, in years), self-discharge rate (loss of charge per time when not in use), efficiency (coulombic efficiency per cycle, energy efficiency, etc.), rate mapping on charge and discharge and charge end-point capacity slippage (the change in the amount of charge that a battery can accept during the final phase of charging over time). There are also application-specific metrics; for EVs, for example, fast charge time (time to charge to 80%) is critical, as is operating temperature range. In essence, performance metrics turn battery behavior into numbers that can be compared and tracked.
NOVONIX’s testing services and R&D revolve around accurately determining these performance metrics for cells and materials. They perform standardized tests to measure capacity (e.g., constant-current charge/discharge), power (pulse tests or high-rate discharges to see capacity at various C-rates), and cycle life (repeated cycling until fade). Using their UHPC system, they gauge coulombic efficiency and charge endpoint capacity slippage, to assist with prediction of cycle life long before a cell actually dies. They also evaluate calendar life by storing cells at elevated temperatures and monitoring capacity loss over time. For internal resistance, they might do both DC and AC measurements. NOVONIX doesn’t just spit out numbers; they analyze the metrics to identify trends and causations. For instance, if a cell’s capacity retention (a metric) is poor at 45°C, they seek to understand why and how to improve it. They compare performance metrics of various chemistries to guide clients on trade-. In sum, NOVONIX ensures that every important performance metric of a battery is measured with high precision and tied back to materials and design choices, driving the development of better batteries.
