Chemistry

Materials science

Lithium-ion battery

Internal resistance

Engineering

Power (physics)

Lithium (medication)

Physics

Electrode

Work (physics)

Organic chemistry

Endocrinology

Quantum mechanics

Electrolyte

Computer science

Battery (electricity)

Physical chemistry

Medicine

Mechanical engineering

Journal of The Electrochemical Society

Lithium-ion batteries can last many years but sometimes exhibit rapid, nonlinear degradation that severely limits battery lifetime. In this work, we review prior work on “knees” in lithium-ion battery aging trajectories. We first review definitions for knees and three classes of “internal state trajectories” (termed snowball, hidden, and threshold trajectories) that can cause a knee. We then discuss six knee “pathways”, including lithium plating, electrode saturation, resistance growth, electrolyte and additive depletion, percolation-limited connectivity, and mechanical deformation—some of which have internal state trajectories with signals that are electrochemically undetectable. We also identify key design and usage sensitivities for knees. Finally, we discuss challenges and opportunities for knee modeling and prediction. Our findings illustrate the complexity and subtlety of lithium-ion battery degradation and can aid both academic and industrial efforts to improve battery lifetime.

Review—“Knees” in Lithium-Ion Battery Aging Trajectories