Electrical energy storage for transportation—approaching the limits of, and going beyond, lithium-ion batteries

TLDR

The rising oil costs, geopolitical concentration of resources, and CO₂ climate impacts drive the need for alternative energy and vehicle propulsion, yet current lithium‑ion batteries lack the energy density and lifespan required for vehicle performance, despite significant technological advances in the past two decades. The study seeks 2‑ to 5‑fold increases in lithium‑ion energy density to enable PHEVs with 40–80 mile all‑electric ranges and EVs with 300–400 mile ranges, and to evaluate whether further 2‑ to 3‑fold gains are achievable for current systems or 5‑fold gains for lithium‑oxygen systems, contingent on overcoming major technical barriers.

Abstract

The escalating and unpredictable cost of oil, the concentration of major oil resources in the hands of a few politically sensitive nations, and the long-term impact of CO2 emissions on global climate constitute a major challenge for the 21st century. They also constitute a major incentive to harness alternative sources of energy and means of vehicle propulsion. Today's lithium-ion batteries, although suitable for small-scale devices, do not yet have sufficient energy or life for use in vehicles that would match the performance of internal combustion vehicles. Energy densities 2 and 5 times greater are required to meet the performance goals of a future generation of plug-in hybrid-electric vehicles (PHEVs) with a 40–80 mile all-electric range, and all-electric vehicles (EVs) with a 300–400 mile range, respectively. Major advances have been made in lithium-battery technology over the past two decades by the discovery of new materials and designs through intuitive approaches, experimental and predictive reasoning, and meticulous control of surface structures and chemical reactions. Further improvements in energy density of factors of two to three may yet be achievable for current day lithium-ion systems; factors of five or more may be possible for lithium–oxygen systems, ultimately leading to our ability to confine extremely high potential energy in a small volume without compromising safety, but only if daunting technological barriers can be overcome.