Inherent Equalization of Lithium-Ion Batteries Based on Leakage Current

This paper studies inherent equalization of lithium-ion batteries based on leakage current. Through constant potential load tests, the leakage current proves to vary exponentially with applied voltage and cell temperature. A hopping model is applied to the solid-electrolyte interface to explain the above-mentioned property. Stability of cell voltages is theoretically proved, which guarantees that stored charges gather near individual cell capacities at a steady state. Simulations agree well with measurements. A photovoltaic system is operated for 11 months during which cell voltages are balanced without external circuit. As far as leakage currents are close, balance of cell voltages is kept.