Understanding Lithium Plating in Lithium-Ion Batteries and Exploring Mitigation Strategies by Self-Heating

Open Access
Author:
Marple, Daniel Robert
Graduate Program:
Chemical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
September 28, 2017
Committee Members:
  • Chao-Yang Wang, Dissertation Advisor
  • Chao-Yang Wang, Committee Chair
  • Michael John Janik, Committee Member
  • Enrique Daniel Gomez, Committee Member
  • Christopher Rahn, Outside Member
Keywords:
  • Lithium ion battery
  • lithium plating
  • self-heating
  • low temperature
  • cycle life
  • pulse heating
  • large-format battery
Abstract:
The integration of lithium ion batteries into the electric vehicle market is dependent on a few key issues. Two of these issues include cycle life and performance at low temperatures. Industrial lithium-ion batteries need to be able to withstand several thousand cycles and operate over a large temperature range so as not to induce range anxiety in drivers in colder climates. One of the major degradation mechanisms that can occur within a battery, especially in cold temperatures, is lithium plating on the graphite anode. Experiments in this dissertation show that the degradation mechanism of LiNi0.6Mn0.2Co0.2O2/graphite high energy cells that causes a premature death is lithium plating. Experiments utilizing specially fabricated research-type cells with forced lithium plating are used to better understand the important variables that drive lithium plating in graphite anodes. Results show that temperature plays a dominant role in the onset of lithium plating, which can even occur at temperatures above 0 oC. In order to mitigate lithium plating in Li-ion batteries, the internal temperature of the battery must be monitored and controlled. This can be obtained through self-heating quickly and efficiently while using a minimal amount of energy. Pulse heating of batteries from 0 oC is examined in order to decrease spatial temperature gradients, lower average activation current and minimize wasted energy due to temperature overshoot when compared to the current continuous heating protocol. The optimal pulse heating protocol is a 2 second on-pulse followed by a 2 second off-pulse. Mitigation of lithium plating in industrial electric vehicle batteries is attempted utilizing the self-heating technology. External heating is unable to heat the battery from sub-zero temperatures while inducing a safety shut-off and large spatial temperature gradients. Conversely, internal heating is successful at heating the cell quickly and uniformly with minimal energy consumed.