Dynamic braking energy management for electric vehicle under battery ageing: A sliding-mode approach with environmental impact assessment

The regenerative braking capability of electric vehicles is strongly influenced by the health of the traction battery. As the battery ages, internal resistance rises and charge-acceptance limits decrease, restricting the amount of regenerative power that can be safely absorbed during braking events. This reduction in regenerative capacity forces a larger share of braking energy to be dissipated through mechanical friction brakes, lowering overall energy efficiency and increasing non-exhaust particulate emissions. This study develops an ageing-adaptive braking energy management strategy that dynamically allocates braking energy between the battery and a controlled brake resistor using a dual sliding-mode control structure. The framework integrates a vehicle longitudinal model, a state of health (SOH) dependent battery model, and discrete-time power flow equations to explicitly account for ageing-driven limitations on regenerative energy. The proposed system is evaluated under Urban, City, and Highway drive cycles for SOH values ranging from 1.00 to 0.40. Results show that ageing produces a significant reduction in regenerative capability and a corresponding increase in brake-resistor utilisation. For Highway driving, peak resistor power rises from 3.6 for a new battery to nearly 12 kW at SOH = 0.40, whereas Urban driving shows much smaller changes. The shift in braking-energy partitioning also reduces friction-brake actuation, yielding quantifiable environmental benefits. Depending on drive cycle and SOH, PM 10 reductions range from 0.0878 to 70 mg per cycle, with PM 2 . 5 reductions up to 28 mg per cycle.