Lithium-ion Batteries from Lignin: a Low Cost, Renewable Anode Material

Abstract

To meet targets set by the Department of Energy, investigators are looking for new ways to reduce the cost of current lithium-ion batteries.  One way is to replace graphite, the conventional anode material, with a lower-cost material.  Lignin, for example, is the second most abundant naturally occurring biopolymer, behind cellulose, and lignin can be carbonized to be used as a more affordable alternative to graphite.  Annually, the pulp and paper industry produces several million pounds of lignin, which is considered a byproduct.  We report here on research performed on lignin-based carbon powders derived from softwood sources for use as anodes in lithium-ion batteries.  Our investigations include comparing the performance of lignin-based carbon powders, carbonized at either 1050 oC or 2000 oC, as well as testing the lignin-based anodes at different thicknesses/loadings.  The carbonized lignin was provided by the Center for Renewable Carbon at the University of Tennessee, and we prepared it into a slurry.  We used the data from half-cells (versus Li metal), to estimate a specific capacity for full-cell calculations.  For full cells, we prepared LiNi0.5Mn0.3Co0.2O2 (NMC532) electrodes as the cathode, with a lignin anode.  The most promising full cells to date are those with lignin carbonized at 1050 oC, coated to a 3-mil thickness.  Given the increasing demand of lithium-ion battery products, an ability to make battery components from renewable resources is extremely important.