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Galvanostatic Intermittent Titration Technique Reinvented: Part II. Experiments

2021; Institute of Physics; Volume: 168; Issue: 12 Linguagem: Inglês

10.1149/1945-7111/ac3939

1945-7111

Stephen Dongmin Kang, Jimmy Jiahong Kuo, Nidhi Kapate, Jihyun Hong, Joonsuk Park, William C. Chueh,

Advanced Battery Materials and Technologies

Following a critical review of the galvanostatic intermittent titration technique in Part I, here we experimentally demonstrate how to extract chemical diffusivity with a modified method. We prepare dense bulk samples that ensure diffusion-limitation. We utilize the scaling with <?CDATA $\sqrt{{t}_{\mathrm{relax}}+\tau }-\sqrt{{t}_{\mathrm{relax}}}$?> t relax + τ − t relax ( t relax : relaxation time; τ : pulse duration), avoiding problems with composition-dependent overpotentials. The equilibrium Nernst voltage is measured separately using small porous particles. This separation between the diffusion measurement and the titration procedure is critical for performing each measurement in a reliable setting. We report the chemical diffusion coefficients of Li x Ni 1/3 Mn 1/3 Co 1/3 O 2 and their activation energy. We extract ionic conductivity and compare it with total conductivity to confirm ion-limitation in chemical diffusion. The measurements suggest that the time scale for diffusion in typical Li-ion battery particles could be much shorter than that of the intercalation/deintercalation processes at the particle surface (Biot number less than 0.1).