2.1 Battery basics and their relevance to aviation

Batteries operate through electrochemical energy conversion, enabling the storage and controlled release of electrical energy [13]. A conventional battery consists of an anode, a cathode, and an electrolyte. During discharge, oxidation at the anode releases electrons, which flow through an external circuit to generate an electric current, while reduction occurs at the cathode to complete the electrochemical reaction. The electrolyte facilitates ionic transfer between the electrodes, thereby maintaining charge neutrality and enabling continuous operation [14].

Secondary (rechargeable) batteries, particularly lithium-based systems, are preferred for aviation applications owing to their higher energy efficiency, rechargeability, and more favorable energy-to-weight ratio compared with primary batteries [15]. Two parameters are fundamental in determining battery suitability for flight applications. Specific energy (Wh kg⁻¹) determines the achievable range and represents how far an aircraft can fly on a single charge, whereas specific power (W kg⁻¹) reflects the battery's ability to deliver high instantaneous power during take-off, climb, and other critical phases of flight. Electric aviation requires an optimal balance between specific energy and specific power, as improvements in energy density are often accompanied by compromises in power capability or safety margins. Battery technologies such as lithium-ion (Li-ion) systems and emerging solid-state chemistries are therefore central to the electrification of flight, as they offer lightweight and high-performance energy storage solutions. Consequently, the development of next-generation batteries with higher gravimetric energy, enhanced thermal stability, and extended cycle life is essential for achieving commercially viable and carbon-neutral aviation.

2.2 Current battery technologies for electrified aviation

Lithium-ion batteries (LIBs) currently dominate as the primary power source for electrified aviation owing to their high specific energy, long cycle life, and well-established manufacturing ecosystem [16]. Initially developed for consumer electronics and later scaled for EVs, LIBs now demonstrate adequate performance for early electric aircraft such as the Pipistrel Velis Electro [17]. Aviation-grade LIBs typically achieve specific energies of 250–270 Wh kg⁻¹ and specific powers exceeding 1,500 W kg⁻¹, supporting short-range operations such as pilot training and local commuter flights [18]. Recent improvements in nickel-rich cathodes and silicon–graphite anodes have increased specific energy but often at the expense of thermal stability and cycle life [8]. Safety, therefore, remains a major concern, as thermal runaway and internal short circuits can lead to fire propagation in high-capacity battery packs [19, 20]. The ground-test battery fire in the Eviation Alice prototype in 2020 underscores the importance of enhanced thermal management and fault-tolerant pack architectures [21].

To address safety and reliability risks, manufacturers are developing improved cooling architectures, enhanced cell isolation strategies, and fault-tolerant pack designs. In addition, advanced battery management systems (BMSs) are being implemented to monitor voltage, temperature, and current at the cell level, thereby ensuring safe operation under variable flight conditions [22, 23]. While LIBs provide the most practical foundation for near-term electrified aviation, their scalability is constrained by limited energy density, thermal safety concerns, and cycle degradation. Continued innovation in cell chemistry, pack integration, and thermal management will therefore determine how electric aviation expands beyond light and short-haul aircraft.

2.3 Emerging chemistries and prototype integration

To overcome the intrinsic energy density ceiling of conventional Li-ion systems, both academic and industrial research efforts are focused on alternative battery chemistries that offer higher gravimetric energy and improved safety. Among these, lithium metal (Li-metal) [24] and lithium sulfur (Li–S) batteries [25] are widely regarded as the most promising near-term candidates for aviation applications. Other chemistries, such as sodium-ion batteries, are also under investigation because of their material abundance and lower cost [26]. However, their relatively low operating voltage and specific energy currently limit their suitability for aviation, where performance-to-weight ratio is critical [16].

At the systems level, several prototype programs have demonstrated the integration of advanced batteries with electrified propulsion architectures. The Eviation Alice aircraft employs a 900 kWh Li-ion battery pack to power dual electric motors, achieving an estimated range of 1,000 km for short-haul operations [27]. NASA's X-57 Maxwell program introduced distributed electric propulsion using twelve small electric motors to reduce drag and improve aerodynamic efficiency [28]. These developments underscore a common design philosophy, wherein distributing electrical loads across multiple high-efficiency motors can partially offset the mass and thermal penalties associated with large centralized power systems [29]. Lithium metal batteries replace the conventional graphite anode with metallic lithium, thereby eliminating the host matrix and increasing the theoretical specific capacity to approximately 3,860 mAh g⁻¹ [30]. Start-ups such as Cuberg [31] and QuantumScape [32] have reported prototype cells with specific energies approaching 369 Wh kg⁻¹ and specific powers of approximately 2,000 W kg⁻¹, alongside projected improvements in cycle life exceeding 1,000 cycles. A major technical challenge remains the suppression of lithium dendrite formation, which can induce internal short circuits and accelerate capacity degradation under high-rate operation. Similarly, Li–S batteries developed by companies such as Oxis Energy have demonstrated gravimetric energy densities approaching 400 Wh kg⁻¹, although challenges related to limited cycle stability and poor volumetric efficiency persist [33]. Collaborative efforts between academia and industry are accelerating progress in these areas. Research groups at the University of California, Berkeley, and the University of Michigan, in collaboration with industrial partners such as And Battery Aero (Palo Alto) and 24M Technologies (Cambridge), have developed advanced electrolyte formulations aimed at enhancing safety and improving charge–discharge kinetics [34–36]. Collectively, these innovations represent incremental yet steady progress toward practical electric aviation across multiple aircraft classes, ranging from light trainers to regional commuter platforms.

In summary, emerging battery chemistries and distributed propulsion demonstrators represent meaningful progress toward viable electric aviation. Although current implementations remain largely confined to general and regional aviation, continued advancements in electrode architecture, electrolyte design, and pack-level thermal management are expected to enable scalable and certifiable energy storage systems for next-generation air transport.

2.4 Research gaps and contribution of this study

Despite substantial advances in electrified propulsion and battery technologies, several challenges continue to impede the realization of large-scale electric aviation. These challenges include increasing energy density, reducing system mass, ensuring operational safety, and improving the life cycle sustainability of energy storage systems. While existing technologies such as LIBs provide a practical baseline, their limited specific energy, thermal stability concerns, and environmental footprint constrain performance and scalability. In addition, the economic and logistical implications of large-scale battery manufacturing, recycling, and end-of-life management remain insufficiently addressed within the aviation context.

This study reviews the limitations of current battery and propulsion systems and evaluates recent advances in battery chemistry, system integration, and hybrid-electric propulsion architectures aimed at overcoming these constraints. By jointly considering performance, safety, cost, and environmental factors, the analysis provides an integrated perspective on the electrified aviation landscape. The resulting insights identify realistic technological pathways toward carbon-neutral air transport and support the development of efficient, sustainable, and safer battery systems optimized for aviation applications.

3.1 Power analysis

An aircraft's ability to sustain flight fundamentally depends on its capacity to generate sufficient thrust. Conventional aircraft achieve this through the combustion of hydrocarbon fuels, whereas electric aircraft rely on high-efficiency electric motors powered by energy stored in batteries. This transition from chemical to electrochemical propulsion introduces unique design challenges, primarily associated with the limited specific power (W kg⁻¹) and specific energy (Wh kg⁻¹) of current battery technologies, which directly govern endurance and payload capability [37].

Figure 1A compares the specific power and specific energy of various battery chemistries, illustrating the substantial performance gap between state-of-the-art LIBs and the levels required for large-scale electric aviation (produced using Granta EduPack [38]). Among commercially available systems, lithium–nickel–cobalt–aluminum oxide (Li-NCA) cells, such as the Panasonic NCR18650, remain industry benchmarks owing to their balanced combination of energy density, power capability, and operational safety (Table 1) [39]. These cells provide an average specific energy of 251 Wh kg⁻¹ and a specific power of 594 W kg⁻¹, outperforming legacy chemistries such as lead–acid and nickel–cadmium batteries [40]. While these advances make Li-ion batteries suitable for small-scale electric aircraft, their gravimetric energy density remains several orders of magnitude lower than that of conventional aviation fuels (≈ 12,000 Wh kg⁻¹) [41].

Figure 1 Performance comparison of battery technologies and propulsion system requirements relevant to electrified aviation. (A) Comparison between different battery chemistries in terms of specific power and specific energy (produced using Granta EduPack [38]). (B) Correlation between maximum power output (kW) and maximum onboard energy (kWh) for representative propulsion systems. Reproduced with permission from Ref. [8]. Copyright 2022, Nature

In addition to battery chemistry performance, Figure 1B correlates the maximum onboard energy (kWh) with the maximum power output (kW) for representative propulsion systems and aircraft classes [8]. Battery-powered systems, including drones, electric vehicles, and pilot-training aircraft, cluster in the lower-left region of the plot, reflecting limited energy and power availability. As aircraft scale in size and mission complexity, both power and energy demands increase sharply: piston engines (10²–10³ kW) power light general-aviation aircraft, turboprop engines (10³–10⁴ kW) serve regional commuters, and turbofan engines (> 10⁵ kW) dominate commercial and wide-body aircraft. Each successive propulsion class requires exponentially higher onboard energy (10²–10⁶ kWh), highlighting the challenge of scaling electric propulsion, as current battery technologies remain several orders of magnitude below the requirements for turbofan-class flight [8].

The power requirements of different aircraft types, from general-aviation aircraft to wide-body jets, are determined by their aerodynamic and propulsion parameters (refer to Supporting Information (SI)). The required propulsive power P_req to sustain level flight is expressed as:$P_{\text{req}}=\frac{1}{2}\rho V^{3}S{C}_{D0}+\frac{2W^2}{\rho VS}\left(\frac{1}{\pi e\text{AR}}\right)$(1)where ρ is the air density (kg m⁻³), V is the flight velocity (m s⁻¹), S is the wing surface area (m²), C_D0 is the zero-lift drag coefficient, W is the aircraft weight (N), e is Oswald's efficiency and AR is the wing aspect ratio.

Using representative aerodynamic parameters and MATLAB-based simulations, the power demand was calculated for typical cruise velocities and altitudes. A conversion efficiency of approximately 75% was assumed to account for electrical-to-mechanical losses in the propulsion system. The results indicate that wide-body aircraft require exponentially higher power owing to their greater mass and cruise velocity, underscoring the intrinsic difficulty of scaling electric propulsion while maintaining acceptable efficiency and safety margins [8].

One of the primary challenges in electric aviation is generating sufficient power for sustained flight. Unlike hydrocarbon fuels, which possess exceptionally high energy and power densities, batteries are constrained by their specific power, defined as the maximum deliverable power per unit mass [42]. This limitation imposes a minimum battery mass required to meet the aircraft's power demand, directly affecting payload capacity and overall feasibility.

Figure 2A compares the minimum required battery mass (refer to SI) with the typical fuel mass allocation for different aircraft classes, including general aviation (Cessna 172), regional aircraft (Saab 340), narrow-body aircraft (A320), and wide-body aircraft (A350). The analysis shows that battery-based propulsion is feasible for smaller aircraft but becomes impractical for larger platforms due to prohibitively high energy-storage mass requirements.

Figure 2 Impact of battery mass and drivetrain efficiency on the feasibility of electric aircraft across different aircraft classes. (A) Minimum battery mass required versus typical fuel mass allocation for various aircraft types. (B) Sensitivity of required battery mass to drivetrain efficiency (η) for representative regional (Saab 340) and narrow-body (A320) aircraft

While Equation (1) defines the aerodynamic power requirement, the actual electrical power drawn from the battery depends on the overall drivetrain efficiency (η), which includes losses in the inverter, motor, gearbox, and propeller. To account for these effects, a sensitivity analysis was conducted by varying η between 0.6 and 0.9 for representative regional (Saab 340) and narrow-body (A320) aircraft. As shown in Figure 2B, improving drivetrain efficiency substantially reduces the required battery mass. For the A320, increasing η from 0.6 to 0.9 results in a battery-mass reduction exceeding 30%, corresponding to several tens of tonnes.

This analysis highlights that advances in motor design, power electronics, and thermal management can deliver immediate system-level benefits independent of improvements in battery chemistry. While achieving higher specific energy remains a long-term objective, enhancing drivetrain efficiency represents a practical near-term pathway for reducing mass penalties and improving the feasibility of regional- and narrow-body electric aircraft.

3.2 Range analysis

Range is one of the most critical performance metrics in aircraft design, as it directly determines operational viability across passenger, cargo, and defense applications. For electric aircraft, achievable range strongly influences both economic competitiveness and environmental benefits relative to conventional fuel-powered aviation. Among the contributing factors, the aircraft's total mass, including the airframe, payload, and battery mass, plays the dominant role in determining attainable range.

The theoretical maximum range (R_max) of an electric aircraft can be expressed as:$R_{\text{max}}=V_{\text{avg}}\frac{e_{\text{b}}.m_{\text{b}}.{\eta }_{\text{tot}}}{\int P_{\text{req}}\text{d}t}$(2)where V_avg is the average cruise velocity of the aircraft (m s⁻¹), e_b is the specific energy of the battery (Wh kg^−¹), m_b is the mass of the battery (kg), η_tot is the overall energy drivetrain efficiency, and P_req is the propulsive power requirement (W) derived from Equation (1). This relation highlights that flight range scales directly with specific energy and efficiency, while it decreases with increasing power demand.

Figure 3 presents modeled cruise-range results for four representative aircraft categories: general aviation (Cessna 172), regional (Saab 340), narrow-body (A320), and wide-body (A350), evaluated under varying battery mass fractions (BMFs) ranging from 0.2 to 0.6. The BMF represents the fraction of the aircraft's maximum take-off mass allocated to batteries. Simulations were performed using MATLAB, assuming representative cruise velocities and aerodynamic parameters obtained from published literature.

Figure 3 Cruise range analysis of electric aircraft under varying battery mass fractions. (A) General aviation aircraft (Cessna 172). (B) Regional aircraft (Saab 340). (C) Narrow-body aircraft (A320). (D) Wide-body aircraft (A350). Results are shown for battery mass fractions between 0.2 and 0.6, bounded by minimum operational mass and maximum take-off mass

The results indicate that increasing battery mass without a corresponding increase in specific energy leads to severe range penalties, particularly for larger aircraft. For comparison, conventional jet fuel has a specific energy of approximately 13.3 kWh kg⁻¹, which is nearly 53 times greater than that of a typical Panasonic NCR18650 Li-ion cell (~ 0.25 kWh kg⁻¹). Consequently, while general-aviation aircraft can achieve practical ranges of several hundred kilometers (km), wide-body aircraft experience range reductions exceeding 95% when powered by current Li-ion technology.

Table 2 summarizes the calculated maximum electric range for different aircraft categories under varying BMF assumptions. Even at optimistic BMF values, the achievable ranges for narrow-body and wide-body aircraft remain far below conventional operational requirements. These findings emphasize that long-haul electric flight remains impractical with existing battery technologies. Conventional aircraft benefit from progressive fuel burn during flight, which continuously reduces mass and improves aerodynamic efficiency, whereas electric aircraft retain nearly constant mass throughout the mission, eliminating this advantage.

Improving electric-aircraft range, therefore, requires simultaneous increases in BMF and battery-specific energy without compromising payload capacity or structural integrity. Conventional aircraft typically allocate 15%–45% of their take-off mass to fuel, depending on mission range (~20% for short-haul and up to ~45% for long-haul operations). In contrast, electric aircraft may require battery mass fractions exceeding 50% to achieve comparable ranges. Realizing such configurations would necessitate lightweight structural materials, aerodynamic optimization, and the integration of batteries into load-bearing aircraft structures.

Figure 4 illustrates the pack-level specific energy requirements needed for different aircraft categories to achieve ranges comparable to conventional aircraft, based on Monte Carlo simulations reported by Bills et al. [43]. Regional aircraft require pack-specific energies in the range of 500–800 Wh kg⁻¹, while narrow-body and wide-body aircraft demand values approaching 700–1,280 Wh kg⁻¹, far exceeding the capabilities of current commercial Li-ion cells (~250–300 Wh kg⁻¹). These requirements are driven primarily by increasing range demands rather than aircraft mass alone. While these projections underscore the challenges associated with electrifying large commercial jets, they indicate that electric propulsion remains feasible for small and regional aircraft[44, 45].

Figure 4 Pack-level specific energy requirements for achieving conventional aircraft ranges. (A) Histogram of required specific energy for different aircraft categories based on Monte Carlo simulations. Reproduced with permission from Ref. [43]. Copyright 2020, American Chemical Society. (B) Projected evolution of pack-level specific energy from current Li-ion batteries toward advanced and solid-state systems, compared with aviation targets shown in Figure 4A. Shaded regions indicate required ranges for regional, narrow-body, and wide-body aircraft

Figure 5 focuses on general-aviation aircraft with mission targets of 200–250 km. As shown in Figure 5A, these aircraft require pack-specific energies of approximately 250–300 Wh kg⁻¹, values that may be attainable using near-term Li-metal and advanced high-nickel Li-ion chemistries. However, practical implementations must account for system-level losses. Empirical data from NASA's Electrified Aircraft Propulsion program and the United States (U.S.) Department of Energy Vehicle Technologies Office indicates that pack-level efficiencies typically range from 75% to 85% of nominal cell energy [18, 46]. As illustrated in Figure 5B, cooling systems, battery-management electronics, and structural supports reduce the effective pack-level specific energy by 15%–25%, such that a nominal 300 Wh kg⁻¹ cell may yield only 225–255 Wh kg⁻¹ at the aircraft system level. Accounting for these losses is essential for accurate range estimation and realistic performance validation.

Figure 5 Specific energy requirements and system-level losses for general-aviation electric aircraft. (A) Histogram of required pack-specific energy for a general-aviation aircraft with a 225 km mission range. (B) Breakdown of effective pack-level specific energy illustrating reductions due to cooling, battery-management systems, and structural components [18,46]

3.3 Propulsion analysis

While advances in battery technologies have enabled sufficient energy storage and power delivery for short-duration electric flights [16], an electric aircraft must also efficiently convert this stored electrical energy into propulsive thrust. The propulsion architecture comprising electric motors, inverters, gearboxes, and propellers plays a decisive role in determining overall system efficiency and, consequently, the achievable flight envelope of electric aircraft.

Rolls-Royce has developed a series of electrified propulsion units (EPUs) specifically designed for electric and hybrid-electric aircraft platforms [47]. Each EPU is capable of delivering a continuous power output of approximately 320 kW, making it suitable for small fixed-wing aircraft and vertical take-off and landing (VTOL) configurations [48]. However, as aircraft scale in size, total propulsion power requirements increase non-linearly, necessitating a substantially larger number of EPUs (Table 3). This scaling introduces significant challenges related to system mass, thermal management, power distribution, and operational reliability. Maintaining high motor efficiency at elevated power levels is particularly demanding and requires advanced cooling strategies and robust, fault-tolerant motor control systems.

Alternative propulsion architectures, such as those demonstrated in NASA's X-57 Maxwell program, employ distributed electric propulsion (DEP) to enhance aerodynamic and propulsive efficiency [49]. In DEP configurations, multiple smaller electric motors are distributed along the wing in place of conventional centralized engines. This approach improves lift distribution, reduces induced drag, and enables precise thrust control. Such advantages are especially beneficial for short-haul and regional aircraft, where noise reduction, energy efficiency, and thrust flexibility are critical performance objectives. Extending DEP concepts to long-duration or high-speed missions remains technologically challenging. At higher Reynolds numbers, characteristic of larger aircraft and faster flight regimes, flow turbulence intensifies and convective heat transfer coefficients increase. While enhanced convection can improve cooling potential, motors and batteries are simultaneously subjected to higher thermal loads due to increased aerodynamic heating and elevated current densities required for propulsion. These conditions amplify power-density constraints, as components must dissipate greater heat flux per unit volume. Consequently, more aggressive thermal-management solutions such as liquid cooling systems and advanced heat exchangers are required to maintain safe operating temperatures and prevent performance degradation.

To bridge the gap between present battery limitations and the power demands of large aircraft, hybrid-electric propulsion has emerged as a practical transitional strategy. In hybrid configurations, conventional turbine engines operate alongside electric motors: batteries supply power during high-demand phases such as take-off and climb, while fuel-based turbines sustain cruise operations and may recharge onboard energy-storage systems [50]. This architecture enables reductions in fuel consumption and overall emissions without compromising operational reliability or range, offering a scalable pathway toward future fully electric commercial aviation.

3.4 Cost analysis

Economic feasibility remains a decisive factor in determining the large-scale adoption of electric aircraft [51, 52]. While electrification offers clear environmental and acoustic advantages, its long-term viability depends primarily on minimizing operational and maintenance costs [53]. This section quantifies key operational cost components for electric aircraft and compares them with those of conventional fuel-based aviation.

3.4.1 Operational cost

Fuel constitutes the second-largest contributor to aircraft operating costs after depreciation and crew expenses. Despite continuous improvements in turbine efficiency, volatility in global oil prices has sustained high operating costs for conventional aviation [54]. In contrast, the operating cost of electric aircraft is dominated by electricity consumption, which depends on both the unit price of electricity and the overall energy efficiency of the propulsion system. Electric propulsion systems typically achieve overall efficiencies of approximately 92%, with propulsive efficiencies in the range of 75%–85%, substantially exceeding the ~30% thermal efficiency associated with jet-fuel combustion [55]. As a result, even when electricity and fuel prices are comparable on a per-unit-energy basis, the higher conversion efficiency of electric systems leads to significantly lower energy expenditure per km.

Figure 6 illustrates historical and regional variations in electricity pricing relevant to electric aviation. Figure 6A shows average monthly wholesale electricity prices in the United Kingdom (UK) from January 2013 to September 2024 [56], highlighting periods of pronounced volatility. Figure 6B compares household electricity prices worldwide between March 2019 and March 2025 [57], demonstrating substantial regional disparities that directly influence the economic viability of electric aircraft operations. The energy consumption rate, derived from Equation (1), provides a direct analog to conventional fuel burn and enables quantitative cost comparisons between electricity-powered and jet-fuel-powered aircraft over equivalent flight distances. Table 4 summarizes the estimated propulsive power demand, energy consumption per 100 km, and corresponding operating cost for representative aircraft classes, assuming a nominal electricity price of £65 per MWh.

Figure 6 Electricity price trends relevant to electric aircraft operation. (A) Average monthly wholesale electricity prices in the United Kingdom from January 2013 to September 2024 [56]. (B) Household electricity prices worldwide from March 2019 to March 2025 [57]

Table 4 Estimated propulsive power demand, energy consumption per 100 km, and operating cost for representative electric aircraft classes assuming an electricity price of £65 per MWh

Aircraft type	Power required (MW)	Energy consumption (10−2 MWh km−1)	Cost per 100 km (10−2 £ km−1)
General aviation	0.11	0.04	3.02
Regional	1.61	0.36	23.35
Narrow-body	22.24	2.69	174.73
Wide-body	104.30	11.57	752.07

The results indicate that smaller aircraft achieve the greatest operational cost advantage due to their lower power requirements and shorter mission profiles. In contrast, wide-body aircraft remain costly to operate on a per-distance basis despite high propulsive efficiency, primarily because of their large mass and high cruise speeds.

To contextualize these findings, Figure 7 presents global jet-fuel prices from January 2016 to January 2025 [58], which exceeded $100 per barrel during several periods. Given jet fuel's energy density of approximately 9.6 kWh L⁻¹, this corresponds to an effective energy cost of roughly £52 per MWh at current exchange rates [48]. Although jet fuel appears less expensive on a per-unit-energy basis, the approximately 2.5-fold higher efficiency of electric propulsion systems results in lower total energy costs over equivalent flight distances. As renewable-energy penetration increases and electricity prices stabilize, electric propulsion is expected to achieve further cost reductions, enhancing the long-term economic competitiveness of electric aircraft relative to conventional aviation [59].

Figure 7 Global jet-fuel price trends from January 2016 to January 2025 [58]

3.4.2 Maintenance cost

Maintenance represents a significant component of airline operating expenditure, particularly for high-utilization fleets. In electric aircraft, maintenance costs are dominated by battery replacement and electrical system upkeep rather than traditional engine overhauls. The replacement frequency of LIBs depends on several factors, including operating temperature, depth of discharge (DoD), and charge–discharge cycle frequency [41]. Assuming an end-of-life threshold corresponding to 80% state of health (SOH), the Panasonic NCR18650 Li-ion cells discussed earlier exhibit a capacity retention of approximately 1,500 charge cycles. Depending on the mission profile, this cycle life may correspond to less than two years of intensive regional aircraft operation (up to eight cycles per day), whereas lighter daily cycling conditions may extend battery service life to approximately four years [40, 60]. The estimated battery replacement energy capacities and associated component costs for representative electric aircraft types are summarized in Table 5, based on market-average LIB prices.

Table 5 Estimated battery replacement energy capacity and component cost for representative electric aircraft types based on market-average LIB prices

Aircraft type	Battery requirements (kWh)	Replacement cost (parts only) (GBP)
General aviation	169.42	22,964.88
Regional	1,280.00	70,423.19
Narrow-body	8,659.50	476,429.38
Wide-body	37,650.00	2,071,432.07

Battery degradation has a direct impact on the long-term economic sustainability of electric aviation [61, 62]. Aircraft with higher energy demands require proportionally larger battery systems that experience higher cumulative cycling, leading to increased replacement costs over the operational lifetime. Although labor, inspection, and certification costs remain non-negligible, these expenses are partially offset by the absence of fuel delivery systems, turbine overhauls, lubrication systems, and exhaust-related maintenance typically associated with conventional propulsion systems.

Figure 8 illustrates projected trends in LIB production costs over time [63]. Continuous reductions in manufacturing cost, coupled with improvements in specific energy, cycle life, and charging efficiency, are expected to reduce long-term maintenance burdens. Consequently, while early-generation electric aircraft may incur higher upfront battery replacement costs, continued technological maturation is anticipated to improve life-cycle economics, gradually narrowing the total cost-of-ownership gap between electric and conventional aviation systems [59].

Figure 8 Projected evolution of LIB production costs over time. Reproduced with permission from Ref. [63]. Copyright 2021, Royal Society of Chemistry

4.1 Production process

The production of LIBs, which form the foundation of electric aircraft propulsion, involves extensive extraction and processing of critical raw materials, including copper, cobalt, nickel, lithium, and rare-earth elements. According to the International Energy Agency (IEA), electric vehicles already require up to six times more mineral inputs than internal-combustion counterparts [67], and this demand increases further for electric aircraft due to their substantially higher energy requirements.

Figure 9 presents the carbon emissions associated with the production of different LIB chemistries [68]. Reported values vary among studies owing to differences in system boundaries, data sources, and assumed manufacturing pathways. In the dataset shown, nickel–cobalt–aluminum (NCA) batteries exhibit the lowest life-cycle emissions, typically below 50 kg CO₂ per kWh, followed by nickel–manganese–cobalt (NMC), lithium–iron–phosphate (LFP), and lithium–manganese–oxide (LMO) systems. However, recent life-cycle assessment studies indicate that LFP batteries can achieve the lowest carbon footprint due to their reliance on more abundant elements such as iron and phosphorus [69].

Figure 9 Carbon emissions associated with the production of nickel–cobalt–aluminum (NCA) Li-ion batteries. Reproduced with permission from Ref. [68]. Copyright 2022, Elsevier

For context, the emission of one tonne of CO₂ corresponds to approximately 6,000 km of travel in a modern diesel vehicle. Given the finite lifespan of battery systems and their periodic replacement, these embodied emissions accumulate over an aircraft's operational lifetime, partially offsetting the benefits of zero-emission flight. Over the long term, however, large-scale recycling of LIBs has the potential to significantly reduce this footprint. Recycled cathode materials require substantially less energy and emit considerably less CO₂ than newly manufactured materials, suggesting that future closed-loop supply chains could mitigate cumulative emissions associated with repeated battery replacement.

4.2 Electricity production

Although electric aircraft eliminate direct combustion emissions during operation, their indirect environmental impact depends strongly on the carbon intensity of the electricity used for charging [70]. In 2022, approximately 44% of the UK's electricity was generated from renewable sources, compared with only 2% in 1990, while the remaining share originated from fossil fuels (primarily natural gas) and nuclear power.

Table 6 summarizes a representative UK electricity generation mix and the associated CO₂ emission intensities for different energy sources. Renewable sources such as wind and solar exhibit emission factors below 5 tonnes GWh⁻¹, whereas fossil-fuel-based generation dominates the remaining carbon footprint.

Figure 10 illustrates the weighted-average carbon intensity of electricity production in the European Union (EU), which is approximately 211 tonnes GWh⁻¹ [71]. While this value is substantially lower than emissions from direct kerosene combustion, it remains dependent on continued decarbonization of the power grid. If electric aircraft were charged exclusively from such a grid, their indirect emissions would reflect this weighted mix. A transition toward predominantly renewable electricity could reduce the operational carbon footprint of electric aviation by more than 80%, highlighting the critical role of clean-energy policy in enabling sustainable electric flight [72].

Figure 10 Carbon emissions associated with electricity production in the European Union. Reproduced with permission from Ref. [71]. Copyright 2024, Our World in Data

4.3 Operational emission comparison

To quantify the operational environmental benefits of electric aviation, Table 7 compares CO₂ emissions per 100 km for representative aircraft classes powered by batteries and conventional jet fuel.

The results demonstrate that electric propulsion provides clear emissions reductions for small and regional aircraft. However, for wide-body aircraft, the environmental advantage diminishes due to large energy demands, battery mass penalties, and reliance on fossil-based electricity generation. While battery-electric propulsion can reduce emissions by 60%–80% for light aircraft, continued improvements in battery energy density, structural weight reduction, and renewable-energy integration are essential to extend these benefits to larger commercial platforms.

4.4 Life-cycle considerations

Achieving sustainable electric aviation also requires responsible end-of-life management of high-capacity battery systems [73, 74]. Improper disposal of LIBs poses risks of toxic metal leaching into soil and groundwater, whereas recycling mitigates these impacts by recovering valuable materials such as lithium, cobalt, and nickel. Current industrial recycling approaches, including pyrometallurgical and hydrometallurgical processes, enable partial material recovery but remain energy-intensive and costly [75, 76]. Emerging direct-recycling techniques, which preserve cathode structure and reduce energy consumption, offer a promising pathway toward low-impact circular battery economies [77]. The integration of such closed-loop recycling strategies will be critical for minimizing life-cycle emissions and ensuring that electric aviation aligns with broader global sustainability objectives.

5.1 Battery-related safety risks

The U.S. Federal Aviation Administration (FAA) has documented 476 onboard incidents involving LIBs since 2006, including six reported cases in 2024 alone [80]. While the majority of these incidents involved consumer electronic devices and had limited operational consequences, a comparable failure in an aircraft's primary energy storage system could be catastrophic.

The most critical hazard associated with LIBs is thermal runaway, a self-accelerating sequence of exothermic reactions that rapidly elevates cell temperature and internal pressure [81, 82]. Laboratory thermal-ramp tests conducted on commercial 18650 NCA-type cells have demonstrated temperature excursions exceeding 1,000°C within seconds once runaway is initiated [83]. The onset temperature is strongly dependent on the state of charge (SOC), with higher SOC levels presenting increased risk. Overcharging and internal short circuits further reduce the threshold for runaway initiation. Importantly, a significant proportion of reported battery fires occur during charging to full SOC. Although this process typically takes place on the ground, it has direct implications for aviation safety, as charging infrastructure, operational protocols, and pre-flight inspection procedures must effectively mitigate risks before batteries are installed and operated onboard.

Figure 11 illustrates the rapid thermal escalation characteristic of LIB thermal runaway, emphasizing the necessity of effective monitoring and thermal management systems. These hazards are amplified in aviation-scale battery packs containing thousands of interconnected cells, where a localized failure may propagate rapidly if not adequately isolated [84]. Consequently, aircraft battery systems require robust containment, controlled venting, and continuous monitoring to prevent escalation under fault conditions.

Figure 11 Temperature evolution of an 18650 Li-NCA cell during a thermal ramp test, illustrating the rapid onset of thermal runaway. Reproduced with permission from Ref. [83]. Copyright 2015, Royal Society of Chemistry

5.2 Regulatory frameworks and standards

To ensure airworthiness, aviation authorities such as the FAA and the European Union Aviation Safety Agency (EASA) have established dedicated certification standards for rechargeable battery systems used in aircraft [85]. A key reference document is RTCA DO-311A, introduced in 2017, which defines qualification procedures for assessing thermal stability, fault tolerance, and containment performance under abusive operating conditions [86].

Compliance with these standards ensures that battery systems meet the stringent reliability requirements of flight-critical components, where acceptable failure probabilities are typically below 10⁻⁹ per flight hour [87]. The certification framework extends beyond individual cells to encompass pack architecture, enclosure design, venting strategies, and fault-isolation mechanisms, forming a multi-layered safety assurance approach consistent with broader aerospace certification practices.

5.3 Mitigation and battery management strategies

A robust battery management system (BMS) is essential for preventing and mitigating battery failure scenarios. The BMS continuously monitors critical parameters such as voltage, temperature, current, and SOC, ensuring that cells operate within predefined safety limits [88]. Compared with automotive systems, aviation-grade BMS designs require substantially higher levels of redundancy, fault detection, and thermal awareness due to more demanding reliability and environmental constraints [89, 90].

An effective BMS can prevent overcharging, balance cell voltages, detect abnormal behavior, and initiate rapid electrical isolation during fault conditions, thereby limiting the propagation of thermal runaway. However, these protective measures introduce additional mass and system complexity, which can marginally reduce overall aircraft efficiency. Optimizing the balance between safety redundancy and energy performance, therefore, remains an active area of research in electric aviation.

5.4 Outlook on safety enhancement

Achieving safety parity with conventional aircraft propulsion systems requires extensive qualification testing, including exposure to vibration, altitude, temperature extremes, and abuse conditions. Although LIB technology has matured significantly, aviation-grade reliability demands continued advances in battery chemistry, thermal architecture, and predictive diagnostics. The development of solid-state batteries, which eliminate flammable liquid electrolytes, offers a promising pathway toward inherently safer energy storage.

In parallel, real-time health-monitoring systems employing machine-learning algorithms to predict degradation and detect early-stage failures could provide an additional preventive safety layer. The aviation sector's stringent certification culture, combined with rapid progress in materials science and data-driven monitoring technologies, indicates that electric aircraft can ultimately achieve and potentially surpass the safety performance of conventional jet-powered systems.