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Dependence of the Heat of Reaction of Li[sub 0.81]C[sub 6] (0.1 V), Li[sub 7]Ti[sub 5]O[sub 12] (1.55 V), and Li[sub 0.5]VO[sub 2] (2.45 V) Reacting with Nonaqueous Solvents or Electrolytes on the Average Potential of the Electrode Material

2006; Institute of Physics; Volume: 153; Issue: 2 Linguagem: Inglês

10.1149/1.2146914

1945-7111

Junwei Jiang, J. R. Dahn,

Advanced Battery Materials and Technologies

Negative electrode materials for Li-ion batteries can be selected from several choices that have different potentials vs Li metal. In this paper, using , , and as examples, we show how the heat of reaction between these electrode materials and nonaqueous solvents or electrolytes depends on the negative electrode potential. The three fully lithiated negative electrode materials react with ethylene carbonate/diethyl carbonate solvent, producing , , and the delithiated phases [C, , or ]. The heat of reaction depends strongly on the negative electrode potential and is for , for , and for , respectively. Thermodynamic considerations show that the heat of reaction per mole of lithium vs electrode potential should vary as , in good agreement with experiment. These results suggest that energy of Li-ion cells can be traded for increased safety by switching to higher potential negative electrode materials.