Capable and efficient: Carbon-coated nanoparticlesof LiMn 0.8Fe0.2PO4 (see TEM image) synthesized by a solid-state reaction were found to be an excellent cathode material for lithium-ion batteries: A stable reversible capacity of up to 165 mA hg -1 was observed, along with excellent cycling, very fast rate capabilities, excellent thermal stability, and very low surface reactivity in lithium-battery electrolyte solutions. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.