Application of manganese materials in lithium ion batteries

American researchers have created a lithium-ion battery that uses manganese as the negative electrode material instead of the traditional cobalt or nickel. This work provides an inexpensive and rich alternative to these increasingly expensive and limited resources, providing a way to meet the rapidly growing demand for lithium-ion energy storage.

Most lithium ion battery anode materials depend on cobalt or nickel because they tend to keep the structure layered and ordered. But in 2014, a team at the Massachusetts Institute of Technology (MIT), led by GerbrandCeder, showed that lithium-ion batteries with disordered structures can work, as long as they are rich in lithium, they can try new ones, and maybe better, materials. .

Ceder and colleagues at the University of California and Lawrence Berkeley National Laboratory have now developed lithium-ion batteries with disordered manganese-based anodes and have shown that they can store more energy than cobalt or nickel. "Our idea is that if we can make a negative electrode and we don't care about delamination, we can use a wider range of metals," said Jinhyuk Lee, the lead author of the Massachusetts Institute of Technology. “We decided to buy manganese because it is one of the cheapest metals.”

Manganese has been used in conventional tiered lithium ion battery anodes, but as a stable metal, almost no electronic storage is involved. Recently attempts to make the negative electrode completely made of disordered manganese and other metal oxides have been limited because they become unstable when lithium ions move from the negative electrode to the lithium-based anode during charging and due to excessive redox activity And lost capacity.

To reduce this activity and obtain high-capacity manganese oxide anodes, Ceder's team found a way to exchange manganese for two electrons, which was done with a high-capacity nickel-based anode instead of one. This involves reducing the manganese valence to Mn2+ by replacing some of the oxyanions with low-valent fluoride anions while exchanging some of the manganese cations with high-valent cerium and titanium ions. This means that manganese ions may undergo a double redox reaction, from Mn2+ to Mn4+, allowing most of the lithium ions to move from the negative electrode to the lithium positive electrode without becoming unstable.

“Our laboratory scale [Battery Cycle Test] results show that our negative electrode has a higher energy density (1000Wh/kg) than the existing negative electrode (600-700Wh/kg),” Ceder said. “But our data has not yet reached commercial scale, so our materials should be further tested and optimized.”

“Although practical applications require further improvements in cycle stability, the reported strategy has great promise and can be explored extensively for a variety of high-priced cations,” commented GlebYushin, who surveyed the Georgia Institute of Technology's energy store. "The need to reduce battery voltage to very low levels may present obstacles to the reported technology being applied to electronic devices, but this is not a big problem for automotive applications."

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