Electrolytes comprising trialkylsilyl phosphorus ester additives

An electrolyte for an electrochemical cell that cycles lithium ions includes an organic solvent, an inorganic lithium salt, and an additive including a chemical compound having a phosphorus, oxygen, and silicon bond (POS additive). The organic solvent includes a mixture of a cyclic carbonate and a linear carbonate. The POS additive includes a trialkylsilyl ester of at least one of phosphoric acid, polyphosphoric acid, phosphonic acid, and phosphorous acid. The electrochemical cell may include a positive electrode comprising a nickel-based electroactive material and a negative electrode comprising a silicon-based electroactive active material.