Up to 99.9999% Coulombic efficiency: New Li-metal battery tech could boost EVs, smartphones, and more

A research team from Shandong University has developed a new electrode material that doesn't go through the physical volume changes that cause Li-metal (lithium-metal) batteries to rapidly degrade. The new material — detailed in Nature Nanotechnology — could lead to commercially viable high-energy-density Li-metal batteries, resulting in longer range EVs and devices with bigger batteries in compact bodies.

Li-metal batteries have long been considered a holy grail in battery technology because they can store more energy per volume than lithium-ion batteries. However, their development has been hindered by multiple problems, including the 'volume change' problem. The volume change issue involves the expansion and contraction of electrodes (critical at the anodes) during charging and discharging, leading to cracks and cell degradation.

The new design addresses this problem by creating a composite host for the lithium using reduced graphene oxide and zinc oxide. This structure features rigid cavities which hold the lithium. This prevents the overall electrode from changing size, while also serving as a “corrosion-proof armor” that shields the reactive lithium from the corrosive electrolyte.

The results were promising. In lab tests, the new electrode enabled a charge efficiency between 99.99% and 99.9999% for almost 2,000 cycles — far exceeding the stability threshold needed for a practical battery. Calculating with the mean number — 99.99495% — the battery will theoretically retain over 95% of its capacity after 1,000 cycles. This calculation doesn't account for other factors.

We reported a similar breakthrough about 2 weeks ago, achieved by a research team from KAIST and LG Energy Solution. That research — published in Nature Energy — focused on a new liquid electrolyte that solves the dendrite problem in Li-metal batteries, resulting in a battery that could deliver a 500-mile range with a 12-minute charge.

The researchers behind the new 'zero-volume-change' electrode are now working to improve their design for commercial use, aiming for commercially available batteries through industry partnerships in the next 3 to 5 years.

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