Lithium ion batteries and electrolytes therefor are provided, which include electrolyte additives having dithioester functional group(s) that stabilize the SEI (solid-electrolyte interface) at the surfaces of the anode material particles, and/or stabilize the CEI (cathode electrolyte interface) at the surfaces of the cathode material particles, and/or act as oxygen scavengers to prevent cell degradation. The electrolyte additives having dithioester functional group(s) may function as polymerization controlling and/or chain transfer agents that regulate the level of polymerization of other electrolyte components, such as VC (vinyl carbonate) and improve the formation and operation of the batteries. The lithium ion batteries may have metalloid-based anodes—including mostly Si, Ge and/or Sn as anode active material particles.