Frontiers in Advanced Materials Research

Electric Vehicles as Integrated Energy, Mobility and Digital Systems: A Critical Review of Technologies, Infrastructure and Emerging Trends

2026-07-29T02:57:13+00:00

Electric vehicles (EVs) are transitioning from stand-alone propulsion products into integrated mobility, energy and digital platforms. This review critically examines the technological foundations and emerging trajectories of battery-electric, hybrid, plug-in hybrid and fuel-cell vehicles, with emphasis on traction batteries, electric machines, power electronics, thermal management, charging infrastructure, grid interaction, connected control, lifecycle sustainability and policy constraints. Global electric-car sales exceeded 17 million in 2024, representing more than one-fifth of new-car sales, but adoption remains geographically uneven and is increasingly limited by charging access, affordability, grid capacity and supply-chain resilience rather than by propulsion feasibility alone. Lithium iron phosphate and nickel-rich layered oxides currently dominate battery-electric vehicles through different cost-energy-safety trade-offs, while sodium-ion and solid-state systems target specific future niches. Fast charging is shifting toward higher-voltage vehicle architectures and higher-power stations, although charging speed remains constrained by lithium plating, heat generation, cell imbalance and local grid demand. Battery-management and thermal-management systems are becoming predictive, cloud-connected and data-driven, but require robust validation, cybersecurity and standardised state-of-health metrics. Smart charging and bidirectional vehicle-to-grid operation can provide grid flexibility, yet battery degradation, interoperability, market rules and user participation remain unresolved. Lifecycle assessment indicates that EV climate benefits depend on electricity mix, vehicle size, battery production and lifetime utilisation; therefore, material efficiency, renewable charging, second-life use and high-yield recycling are essential. The review proposes a co-design framework linking vehicle efficiency, battery durability, charging convenience, grid services and circularity. Future progress will depend on scalable low-cost chemistries, interoperable charging standards, low-carbon manufacturing, safer automation and policy mechanisms that make electrification accessible beyond premium passenger cars.

Filter-Blocking Tendency of Biodiesel and Biodiesel-Diesel Blends in Compression-Ignition Fuel Systems: Mechanisms, Test Methods and Mitigation

2026-07-29T03:07:31+00:00

Biodiesel can reduce petroleum dependence and improve the lubricity and renewable content of compression-ignition fuels, but its field reliability is strongly influenced by filterability. Filter blocking is not produced by a single contaminant or temperature threshold. It results from coupled effects of feedstock fatty-acid composition, incomplete transesterification, saturated monoglycerides, sterol glucosides, soaps, residual metals, particulate matter, water, microbial growth, oxidative ageing and low-temperature crystallisation. This review critically synthesises the mechanisms by which these species form, agglomerate and deposit within vehicle and dispenser filters. It distinguishes filter-blocking tendency from cloud point, cold-filter-plugging point, particulate contamination and cold-soak filtration, and explains why no individual laboratory method reproduces every field failure. ASTM D2068 evaluates the filtration behaviour of middle-distillate fuels and biodiesel blends, whereas ASTM D7501 targets cold-soak filter-blocking potential of B100. Their outputs should be interpreted together with oxidation stability, glyceride composition, particulate loading and actual thermal history. Evidence from B20 and higher blends shows that pressure-drop growth depends on feedstock, fuel age, temperature cycling and contaminant interactions rather than biodiesel concentration alone. Mitigation is most effective when implemented as a hierarchy: rigorous conversion and purification, removal of minor precipitating species, oxidation control, dry and clean storage, climate-appropriate blending, validated cold-flow improvers, suitable filter design and condition-based maintenance. A research framework is proposed for deposit-resolved chemical analysis, standardised accelerated ageing, pressure-drop sensing and predictive filter-life modelling. The review concludes that filterability must be treated as a systems property linking fuel chemistry, logistics, climate and engine hardware, rather than as a pass/fail property of freshly produced biodiesel.

Kevlar K29/PAN-Based Carbon Fibre Hybrid Composites for Aerospace Structures: A Critical Review of Architecture, Processing, Damage and Design

2026-07-29T03:07:12+00:00

Hybridisation of high-modulus carbon fibres with impact-tolerant aramid fibres is an established strategy for mitigating the brittle damage response of carbon-fibre-reinforced polymers while retaining structural efficiency. This review critically evaluates Kevlar K29/polyacrylonitrile (PAN)-based carbon-fibre hybrid composites for aerospace structures, with emphasis on constituent behaviour, hybrid architecture, manufacturing routes, mechanical performance, damage mechanisms, environmental durability, modelling, inspection and certification. The literature shows that the hybrid effect is not an intrinsic material constant; it emerges from interactions among fibre modulus mismatch, strain-to-failure mismatch, ply location, areal density, matrix toughness, interface chemistry, impact energy and test geometry. Carbon-face/Kevlar-core laminates generally preserve flexural rigidity and compression-after-impact strength, whereas Kevlar-rich outer layers improve penetration resistance and visible damage tolerance at the cost of surface stiffness and compressive stability. Interply hybrids are easier to manufacture and certify, while intraply woven, braided and three-dimensional architectures provide more distributed energy absorption but introduce complex mesoscale stress transfer and modelling requirements. Vacuum infusion, resin-transfer moulding, prepreg-autoclave processing and emerging out-of-autoclave routes are compared in terms of void control, fibre wet-out, thickness uniformity and scalability. Persistent limitations include delamination, moisture-sensitive aramid interfaces, difficult machining, poor through-thickness conductivity, property scatter and a shortage of standardised long-duration fatigue and environmental datasets. A design framework is proposed that links mission loading to laminate architecture, processing quality, damage-tolerance metrics and non-destructive inspection. Future progress requires multi-objective optimisation, physics-informed damage models, in-situ sensing, recyclable matrices and full-scale validation under combined impact, fatigue, temperature and moisture exposure.