A combination of a Li 4 Ti 5 O 12 (LTO) anode and 4 V-class cathodes has been electrochemically studied with a view to its adoption for 12 V-class bipolar batteries. Five series-connected LTO/LiMn 0.85 Fe 0.1 Mg 0.05 PO 4 (LMFP) cells harmonized well with a useable voltage range of 12 V lead-acid batteries, which is suitable for low-voltage system applications. The LMFP cathode had excellent cycle life performance during high-temperature cycling at 60 • C and over-discharge cycling tests. In the case of the LTO/Al and the LMFP/Al electrode using an Al current collector in a hybrid solid electrolyte consisting of a cubic garnet-type Li 7 La 3 Zr 2 O 12 and a gel polymer, lithium insertion and extraction occurred smoothly without irreversible reactions in the potential range of 1 to 4.5 V vs. Li/Li + . The thin hybrid solid electrolyte with thickness of a few micrometer exhibited not only high-rate discharge but also a low self-discharge for practical use. It was demonstrated that the fabricated 12 V-class bipolar LTO/LMFP battery with a capacity of 102 mAh had the average discharge voltage of 12.5 V, the energy density of 90 Wh kg −1 , and the output power density of 1500 W kg −1 for 10 s. The 12 V-class bipolar LTO/LMFP battery is expected to be suitable for low-voltage systems. Lithium-ion batteries using Li 4 Ti 5 O 12 (LTO) anode realize high power, long life, and safety for automotive and stationary power applications because the LTO electrode has the advantages of nano-size particle, no lithium plating at quick-charging and in low-temperature conditions, outstanding safety for internal short-circuit, and thermal stability under high-temperature conditions. 1-5 There have recently been growing expectations, that the LTO-based lithium-ion batteries will be an excellent match for low-voltage system applications such as 12 V start-stop systems for vehicles 5 and the replacement of lead-acid batteries for stationary power supply.6,7 The start-stop batteries will be stressed by repeated starting and out-put high-power for cold-cranking operation. The LTO-based batteries may solve these problems and have good voltage harmonization with lead-acid batteries. 12 V-class batteries consisting of five series-connected LTO-based cells with LiMn 2 O 4 cathode have already been applied to start-stop vehicle systems. 5 We have been developing olivine LiMn 1-x Fe x PO 4 (LMFP) materials as promising cathodes for large-scale 12 V-class batteries in view of the excellent safety and life performance because the LMFP has high thermal stability compared to that of 4 V-class cathodes such as LiCoO 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 , and LiMn 2 O 4 .8 Lithium-ion cells with a combination of the LMFP cathode and the LTO anode exhibited a voltage plateau of about 2.5 V for Mn 3+ /Mn 2+ redox, excellent safety, and high-energy density compared to LTO/LMO cell, indicating the possibility of promising batteries for 12 V lead-acid replacement batteries and stationary power sources. 8,9 We have focused recently on bipolar battery technologie...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.