Molicel P60B for eVTOL and Aviation: How Simulation Reveals the True Potential
- Kieran O'Regan
- 1 day ago
- 10 min read
Molicel P60B Introduction
Molicel continues to lead in high-performance lithium-ion technology, developing cells that balance exceptional energy, power, and reliability for demanding applications across aviation, drones, motorsport, and defence. The Molicel P60B builds on this legacy as a next-generation 21700 cylindrical cell, engineered for systems where energy density and efficiency are critical.
When comparing the Molicel P50B vs P60B, the performance gap is clear. The P60B offers a nominal capacity of 6.0 Ah and 21.6 Wh of energy, around 20% more than the P50B’s 18 Wh. This higher energy density enables lighter airframes, longer range, and lower system costs through simplified battery pack designs. When the P50B is compared to the P60B, the P60B provides clear advantages in efficiency, weight reduction, and overall system performance.
The P60B achieves a gravimetric energy density of 288 Wh/kg, a gravimetric power density of 4800 W/kg, and supports a 100C maximum continuous discharge rate. These figures illustrate its strong balance between energy and power performance, though it does not demonstrate the same peak power capability as high-power predecessors like the P50B.
In this blog, we analyse how the P60B performs under real-world conditions using The Voltt, our cell selection and simulation platform. By combining laboratory data with empirical-based equivalent circuit models, we assess the cell’s electrical and thermal characteristics to help engineers make confident design decisions.
Start exploring battery data and models like the Molicel P60B with a 14-day free trial of The Voltt.
The Importance of Accurate Cell Selection
Choosing the right cell is one of the most important decisions in battery system design, directly influencing both performance and project economics. A well-matched cell can reduce pack mass, simplify cooling requirements, and lower manufacturing costs, while a poor choice can lead to inefficiencies that compound through the entire system. Simulation and validated data are therefore essential to make informed trade-offs between energy density, power capability, and cost.
To understand how the Molicel P60B performs in real-world applications, we go beyond the manufacturer datasheet and carry out physical testing and simulation-based analysis including, constant current, constant power, and and a representative eVTOL flight cycle. The eVTOL profile features high-power demands during take-off and landing, followed by steady cruise operation, providing an accurate reflection of the mixed load conditions seen in electric aviation systems.
While manufacturer datasheets provide useful baseline metrics such as capacity, voltage limits, and current ratings, the data often lacks the transparency and rigour required for system-level design. Variations in testing methodology, missing details on state of charge definitions, thermal boundaries, and calibration resistances can make it difficult to reproduce results with confidence. As a result, engineering teams frequently need to repeat characterisation tests or seek third-party verification before trusting the data for model creation or pack design.
Simulation enables:
Faster design iteration to accelerate innovation.
Reduced physical testing and lower validation costs.
Greater confidence in system design through broader operating insights.
This approach helps reduce development time, cost, and risk when integrating the P60B into eVTOL and other high-performance systems.
(1) Constant Current Testing - Capacity Check
To verify the nominal capacity of the Molicel P60B, we conducted a physical capacity check under controlled laboratory conditions. The cell was discharged at C/30 and 1C at 25°C to compare measured capacity and voltage behaviour. At C/30, the cell delivered 5.86 Ah, which aligns closely with the manufacturer’s rated specification. This confirms the P60B as one of the highest-energy 21700 cells we have tested to date, offering exceptional capacity without significant voltage instability across the discharge range.
At the time of testing in August 2025, these were early sample cells, and performance is expected to improve further as Molicel refines the chemistry and transitions the P60B into full-scale production.
(2) Constant Current Simulation Testing
To assess how the Molicel P60B responds to increasing current demand, we ran a series of constant current discharges at 1C, 3C, 5C, and 10C. This provides a clear view of rate capability, showing how the cell maintains voltage, power, and thermal stability as current increases.
Although the equivalent circuit models (ECMs) used here are tuned for accuracy under dynamic drive cycles, this steady-state analysis remains useful for comparing discharge behaviour and identifying trends in capacity retention and temperature response.
At lower discharge rates, such as 1C and 3C, the voltage curve remains relatively high and consistent, reflecting low internal resistance and good access to stored energy. As the rate increases to 5C and 10C, the voltage drops more rapidly, and the available capacity decreases, highlighting the limits of the P60B under sustained high-current operation.
The power response provides a clear picture of how the cell delivers energy across the SoC window. At higher states of charge, where voltage is higher, the power output remains stable and efficient. As the SoC falls below, power delivery begins to taper due to increased internal resistance and voltage decline. This behaviour is important when sizing packs for applications that rely on consistent power delivery over a wide SoC range, as it defines the practical energy window that can be used before voltage or thermal limits constrain operation.
Temperature rise follows a similar pattern, scaling closely with discharge rate. The cell maintains near-ambient conditions at 1C (below 35 °C), but temperatures climb past 75°C at 5C and approach 80°C at 10C, reaching the practical thermal cut-off. These results emphasise that while the P60B can tolerate short bursts of high discharge, its advantage lies in energy density and predictable behaviour within moderate SoC ranges, rather than extreme continuous power.
Summary of Performance Metrics (using simulation)
C-Rate | Discharge Current (A) | Capacity Delivered (Ah) | Capacity Retention (%) vs 5.85 Ah minimum capacity | Max Cell Temp (°C) |
1C | 6.0 | 5.60 | ~96% | ~33 |
3C | 18.0 | 5.35 | ~92% | ~55 |
5C | 30.0 | 5.25 | ~88% | ~77 |
10C | 60.0 | 1.75 | ~30% | ~80 (thermal cut-off) |
Simulations were performed at current levels of 6 A, 18 A, 30 A and 60 A starting from:
Initial SoC: 100%
Initial Cell Temperature: 25°C
Heat Transfer Coefficient: 50 W/m²·K (representing moderate passive cooling)
Why This Matters for Engineering Design
Understanding constant current performance gives engineers insight into voltage stability and thermal limits under load. For the Molicel P60B, this data shows strong capacity retention up to 3C, with heat generation with heat generation becoming the limiting factor at higher C-rates as the cell approaches its thermal cut-off near 80°C. For high-power applications, the ability to deliver short bursts of current without excessive heating or voltage drop is critical. These insights guide decisions about:
Pack design (e.g., parallel strings to distribute load)
Thermal management systems (e.g., whether passive cooling is sufficient)
De-rating factors to extend lifetime in mission profiles
(3) Constant Power Simulation Testing
Constant power testing shows how the Molicel P60B responds to sustained power demand, where current dynamically adjusts as voltage drops during discharge. This method captures more realistic system behaviour than fixed-current tests, especially for applications that have power-based demands.
At lower power levels, such as 10 W and 25 W, the voltage remains high, indicating low internal resistance and efficient energy delivery. As power increases to 50 W, voltage drop becomes more evident, and at 80 W, the drop steepens significantly, reflecting increased internal heating and resistive losses. These results demonstrate the P60B’s energy-optimised design, performing well at moderate power while showing its limits at high sustained load.
The current response illustrates how power demand translates directly to electrical stress. At constant power, current rises as voltage falls, increasing nonlinearly through the discharge. At 10 W, current remains around 2.5 A, while 25 W draws ~6 A, 50 W rises to ~12 A, and 80 W peaks above 20 A as the cell nears depletion. This behaviour highlights the compounding effect of low voltage at high power, which accelerates heat generation and reduces effective efficiency.
The thermal response follows the expected trend: temperature remains near ambient at 10 W (around 30°C), rises moderately to 38°C at 25 W, increases further to about 53°C at 50 W, and reaches roughly 70°C at 80 W. Beyond this point, thermal cut-offs or derating would be required to maintain safe operation. The data reinforces that while the P60B can tolerate brief high-power bursts, it is optimised for applications that prioritise energy density and stability over prolonged high-rate discharge.
Summary of Performance Metrics (using simulation)
Power / W | Capacity Delivered (Ah) | Capacity Retention (%) vs 5.85 Ah minimum capacity | Max Cell Temp (°C) |
10 | 5.75 | 98.3 % | 30 |
25 | 5.50 | 94.0 % | 38 |
50 | 5.40 | 92.3 % | 53 |
80 | 5.10 | 87.2 % | 72 |
Simulations were performed at power levels of 10 W, 25 W, 50 W, and 80 W starting from:
Initial SoC: 100%
Initial Cell Temperature: 25°C
Heat Transfer Coefficient: 50 W/m²·K (representing moderate passive cooling)
Why This Matters for Engineering Design
Understanding constant power behaviour provides engineers with a realistic view of how batteries perform in operation, where power rather than current determines system behaviour. For aviation and eVTOL applications, the Molicel P60B maintains consistent output up to about 50 W, after which temperature rise accelerates toward 70°C, marking the boundary for sustained discharge. These findings are essential for linking cell-level performance to aircraft-level reliability. They guide decisions about:
Powertrain design (for example, matching cell configuration to motor power demand)
Thermal control systems (such as sizing heat exchangers or airflow pathways)
Mission planning and derating to ensure consistent performance throughout flight phases
(4) Simulated Performance Data: Real-World eVTOL Mission Profile
To assess the performance of the Molicel P60B in an aviation environment, we modelled a full eVTOL flight cycle incorporating take-off, cruise, and landing. The simulation provides a detailed view of how the pack behaves under realistic power, voltage, and thermal demands typical of electric aircraft.
The simulated pack consisted of 216 cells in series and 28 in parallel, giving a nominal voltage of 799 V and a total stored energy of approximately 134 kWh. The model was run under representative aviation conditions: an ambient temperature of 25°C, an initial cell temperature of 35°C, a heat transfer coefficient of 70 W/m²·K (reflecting moderate forced-air cooling), and a starting state of charge of 98%. The pack operated safely within a 2.5 V minimum cell voltage and an 80°C maximum cell temperature limit.
Across the flight cycle, the pack experienced a 48.7% drop in state of charge, completing the mission with 49.3% remaining—demonstrating that roughly half of the total capacity is required for a standard mission, consistent with industry practice for safety reserves. The total energy throughput was 64.2 kWh, with a peak power draw of 631 kW and an average of 254 kW. Peak current reached 923 A, while the average remained around 324 A. Voltage was stable throughout, averaging 803 V with a minimum of 684 V during the landing phase.
Thermally, the system showed strong stability. Peak temperature reached 41.9°C, with a total rise of 6.9°C over the mission. The peak heat generation was 96 kW, while the average was 19.6 kW, with maximum cooling demand reaching 388 W per cell group. These results indicate effective thermal management even under transient, high-power conditions typical of eVTOL take-off and landing.
Pack Summary:
Configuration: 216S × 28P
Nominal voltage: 799 V
Total energy: 134 kWh
Starting SoC: 98%
ΔSoC: 48.7% (End SoC 49.3%)
Power peak/average: 631 kW / 254 kW
Current peak/average: 923 A / 324 A
Voltage min/average: 684 V / 803 V
Temperature peak/rise: 41.9°C / 6.9°C
Heat transfer coefficient: 70 W/m²·K
Ambient temperature: 25°C
Why This Matters for Aviation Design
Understanding how the P60B behaves under an eVTOL mission cycle connects laboratory data to real flight performance. The pack maintains voltage stability and manageable temperature rise across demanding thrust phases, showing that it can deliver high power transients without excessive heat generation or voltage drop. This level of predictability is vital for translating cell data into safe, certifiable aircraft systems. It informs:
System architecture (defining the balance between series voltage and parallel redundancy)
Cooling strategy (ensuring heat rejection capacity matches mission load)
Operational limits and safety margins for repeated flight cycles and rapid turnaround times
Key Insights from the Simulated Performance
The Molicel P60B delivers high energy and stable performance across both steady and dynamic load conditions, making it well suited for electric aviation. Through a combination of constant current, constant power, and eVTOL mission simulations, we can observe how the cell’s electrical and thermal behaviour scales from laboratory testing to real system operation.
Constant current testing showed strong voltage stability and controlled heating up to moderate C-rates, confirming the P60B’s reliability for sustained discharge in energy-driven systems. Constant power testing revealed high efficiency under moderate loads, with thermal response increasing at higher sustained outputs—providing clear guidance for defining safe continuous operating limits.
At pack level, the eVTOL simulation demonstrated how these cell-level trends hold true in real-world conditions. The configuration maintained voltage stability through thrust peaks and delivered consistent energy throughout the flight cycle, confirming the P60B’s suitability for high-demand aviation use cases where energy efficiency, predictability, and safety are critical.
These insights are key to accelerating the cell selection process. By combining validated laboratory data with simulation, engineers can assess performance trade-offs faster, refine pack designs earlier, and make confident, data-backed decisions that shorten development timelines and reduce technical risk.
To accelerate your cell evaluation of Molicel P60B and 30+ performance other cells in The Voltt, access our 14-day free trial of The Voltt.
About:Energy
About:Energy is a battery technology company on a mission to simplify and accelerate battery development. We provide high-accuracy models, curated cell performance data, and simulation-ready tools that remove the need for costly and time-consuming in-house testing.
Our platform is used by engineers and hardware teams across industries, from automotive and aerospace to drones and defence, to validate, select, and integrate the right cells with confidence. By bridging the gap between lab-grade data and system-level design, we help battery teams solve key design challenges such as balancing energy, power, and thermal constraints. This enables product teams to move faster, reduce risk, and stay ahead of the electrification curve.
