The paper by J.B. Bates, N.J. Dudney, B. Neudecker, A. Ueda, and C.D. Evans from Oak Ridge National Laboratory discusses the development and properties of solid-state thin-film lithium and lithium-ion batteries. These batteries, less than 15 μm thick, have applications in consumer and medical products and are useful for studying lithium intercalation compounds. The batteries consist of crystalline or nanocrystalline oxide-based cathodes (e.g., LiCoO₂ and LiMn₂O₄) and anodes made of lithium metal, inorganic compounds (e.g., Si-Ti oxynitrides), or metal films. The electrolyte is a glassy lithium phosphorus oxynitride (Lipon). Crystalline LiCoO₂ cathodes can deliver up to 30% of their maximum capacity between 4.2 and 3 V at discharge currents of 10 mA/cm², with capacity loss negligible over thousands of cycles. Nanocrystalline LiMn₂O₄ cathodes exhibit significant capacity at 5 V and 4.6 V due to manganese deficiency and lithium excess. The 5-V plateau is attributed to the oxidation of Mn ions to higher valence states. The hysteresis observed in the discharge-charge curves of nanocrystalline LiMn₂O₄ cathodes is due to true hysteresis rather than kinetically hindered relaxation. Extended cycling at 25°C and 100°C leads to grain growth and evolution of charge-discharge profiles towards those of well-crystallized films. The paper also discusses the performance of lithium-ion cells with in situ plated lithium anodes, which can tolerate solder reflow conditions and deliver high energies. The authors conclude by discussing the applications and commercialization potential of these thin-film batteries, including implantable medical devices, CMOS-based integrated circuits, and rf identification tags.The paper by J.B. Bates, N.J. Dudney, B. Neudecker, A. Ueda, and C.D. Evans from Oak Ridge National Laboratory discusses the development and properties of solid-state thin-film lithium and lithium-ion batteries. These batteries, less than 15 μm thick, have applications in consumer and medical products and are useful for studying lithium intercalation compounds. The batteries consist of crystalline or nanocrystalline oxide-based cathodes (e.g., LiCoO₂ and LiMn₂O₄) and anodes made of lithium metal, inorganic compounds (e.g., Si-Ti oxynitrides), or metal films. The electrolyte is a glassy lithium phosphorus oxynitride (Lipon). Crystalline LiCoO₂ cathodes can deliver up to 30% of their maximum capacity between 4.2 and 3 V at discharge currents of 10 mA/cm², with capacity loss negligible over thousands of cycles. Nanocrystalline LiMn₂O₄ cathodes exhibit significant capacity at 5 V and 4.6 V due to manganese deficiency and lithium excess. The 5-V plateau is attributed to the oxidation of Mn ions to higher valence states. The hysteresis observed in the discharge-charge curves of nanocrystalline LiMn₂O₄ cathodes is due to true hysteresis rather than kinetically hindered relaxation. Extended cycling at 25°C and 100°C leads to grain growth and evolution of charge-discharge profiles towards those of well-crystallized films. The paper also discusses the performance of lithium-ion cells with in situ plated lithium anodes, which can tolerate solder reflow conditions and deliver high energies. The authors conclude by discussing the applications and commercialization potential of these thin-film batteries, including implantable medical devices, CMOS-based integrated circuits, and rf identification tags.