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In 1800, Volta invented the world renowned voltaic cell. Events succeeded quickly with the development of faster, smaller, lighter batteries. Batteries which work together in packs for more power, batteries which can be recharged and used over and over. New chemistries have been developed for better performance and to help the environment.

Recently, rechargeable batteries with high energy density are in great demand as energy sources for various purposes, e.g. portable electronics such as laptop computers and cellular phones, hybrid electric vehicles, zero emission electric vehicles, load leveling in electric power. Lithium secondary batteries are the most promising to fulfill such needs because of their intrinsic high discharge voltage. In 1991, the first lithium secondary battery of high quality and revolutionary concept was put on the market by Sony. The rechargeable lithium-ion battery with high energy density and power capability has become an important power source for portable electronic devices, such as cellular phones and laptop computers and, more recently, hybrid electric vehicles (HEV)




In the commercial battery, called the “lithium ion battery”, lithium ions swing between lithium metal oxide, LiMO2, in its positive electrode (cathode) and carbon material in its negative electrode (anode) through an organic liquid electrolyte dissolving an inorganic lithium salt during charge or discharge process. The past excellent results of fundamental research and technology have been used to develop the lithium secondary battery. However, electronic devices require more high performance battery with high energy density and safety in year by year, indicating development of new alternative cathode and anode materials.

A new concept cathode material, a spherical core-shell structure was developed to circumvent the drawbacks of each positive material. We have discovered a spherical core-shell material with a Li[Ni0.8Co0.1Mn0.1]O2 core and a Li[Ni0.5Mn0.5]O2 shell. A high capacity was delivered from the LiNi0.8Co0.1Mn0.1O2 core, while the high thermal stability stemmed from the Li[Ni0.5Mn0.5]O2 shell.

The core-shell structured Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2/carbon cell had a superior cyclability and thermal stability relative to the Li[Ni0.8Co0.1Mn0.1]O2 at the 1 Crate for 500 cycles. The core-shell structured Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 as a new positive electrode material is a significant breakthrough in the development of high-capacity lithium batteries. The novel technology of core-shell gives rise to a new area for the development of advanced Li-ion batteries with a high energy density, long cycle life and enhanced safety.
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