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Tokyo researchers discover structure and transport properties of intermediate stage in Li-ion batteries; may shorten charging time

Researchers at the University of Tokyo and Tokyo Institute of Technology have discovered the structure and transport properties of an “intermediate state” in LiFePO4 lithium-ion batteries. These findings, reported in a paper in the journal Angewandte Chemie International Edition, may help accelerate battery reaction speed and significantly shorten battery charging time.

Although there is strong demand to minimize battery-charging time, the mechanisms of battery charge and discharge reactions have yet to be fully understood. While the existence of an “intermediate state” that accelerates battery charge and discharge reactions has been suggested, there was no firm experimental evidence to support its existence and previous research had suggested that the short lifetime of the intermediate state would render a systematic investigation of its properties impossible.

Professor Atsuo Yamada’s research group at the University of Tokyo Graduate School of Engineering has now developed a novel technique to stabilize the intermediate state.

The group found a striped pattern of layers of densely and loosely packed electrons. Lithium ions distribute themselves so as not to disturb this striped pattern. In addition, the intermediate state showed high lithium/electron conductivity compared to the charged or discharged state. That is, both lithium ions and electrons could move faster in the intermediate state, contributing significantly to accelerating lithium-ion battery charge and discharge reactions.

The findings were contrary to expectations.

The intermediate state showed a long lifetime, once we were able to optimize the synthesis conditions. We were also successful in stabilizing the intermediate state with almost 100% purity. It was surprising to find that conductivity was hugely enhanced in the intermediate state. We hope to develop rechargeable batteries with quick charging time by applying our findings to the design of materials and conditions that are optimum for creating a stable intermediate state.

—Prof. Yamada


  • Nishimura, S.-i., Natsui, R. and Yamada, A. (2015), “Superstructure in the Metastable Intermediate-Phase Li2/3FePO4 Accelerating the Lithium Battery Cathode Reaction.” Angew. Chem. Int. Ed. doi: 10.1002/anie.201501165


Henry Gibson

The quick charging of automobile batteries requires far more demand on the electrical systems than most people assume and far more expensive equipment to do it which is right now idle most of the time and consuming power in most cases like old plug in wall transformers for charging phones.

A natural gas or propane powered engine generator would be the cheapest fast charging equipment to build and operate. Its size would only indicate the massive size and expense of present fast charging systems.

a stationary large battery could also provide the necessary power but would have to be slow charged for the next vehicle.

Stationary batteries at peoples homes can be a benefit to the electrical system and fast charging of automobiles. Even cheaper manufacturing facilities than the ones at GE could make Durathon or ZEBRA type batteries at much lower cost for every new house of sufficient size and the power company could use them to support the system and pay the home owner and the cost would be in the mortgage because they would be required by law just like efficient heaters and shower heads. They would last far longer than water heaters with no maintenance at all. After twenty years most of the cells would still work well enough for continued use, and could be put into less demanding services if better or bigger ones were needed for increased demand. ..HG..

Henry Gibson

The set of durathon batteries could be directly connected to the drive electronics of air conditioners plus furnaces and refrigerators and freezers and stoves and charging of the batteries would be cut off during high demand hours and the power company could tap into the battery charge during that period as well to boost the energy in the system. Batteries would be fully charged at low power use times, and they would be available during power failures. Charging of electric cars would also happen at low power use time except if a quick charge had to be taken from the battery. ..HG..

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