Researchers Tout Lithium Anode Breakthrough

A research team at Stanford University says it has found a way to equip batteries with stable all-lithium metal anodes. They say the breakthrough opens the possibility of tripling the capacity of today's lithium-ion batteries at 25% the cost of current graphite or silicon anodes.

The scientists who include Steven Chu, former U.S. Secretary of Energy and Nobel laureate report their results this week in the online journal Nature Nanotechnology.

Lithium is considered the Holy Grail of anodes because it is light and offers the highest energy density. But the chemically and structurally fussy material until now has thwarted attempts to use it in batteries.

The key to the Standford's approach a honeycomb film of non-reactive amorphous carbon nanospheres only 20 nanometers thick. The layer allows ions through but shields the anode surface from forming dendrites that would drastically shorten the lifespan of the battery.

The Stanford scientists say their nanosphere layer is strong and flexible enough to cope with the expansion and contraction of the lithium anode as it absorbs and discharges ions. Unlike the lithium anode itself, the layer also is chemically stable.

The team notes that batteries need a coulombic efficiency of at least 99.9% to be commercially viable. Previous unprotected lithium anode systems have reached 96% initial efficiency but deteriorated to less than 50% after fewer than 100 charge/discharge cycles.

The Stanford researchers say their anode maintains 99% efficiency after 150 cycles. They believe more engineering and new electrolytes will result in a practical lithium metal anode design.