Specifically, we study the reductive decomposition of the organic electrolytes ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC). The reaction pathways studied here are similar to those investigated previously by Balbuena and coworkers using DFT. We perform accurate benchmark calculations using a variety of high level WF methods, and then evaluate a range of DFT functionals; our work should be useful for the future development of accurate force field parameters for large scale atomistic simulations of battery electrochemistry. In addition to our evaluation of a range of DFT function-als, we also use the EC decomposition to compare three accurate WF methods capable of serving as a benchmark: coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)], 28 its low-scaling variant via domain-based local pair natural orbitals [DLPNO-CCSD(T)], and phaseless auxiliary field quantum Monte Carlo (ph-AFQMC) using a Kohn-Sham determinant trial wavefunction. We find that the three methods yield similar reactions energetics (within a few kcal/mol), and this internal consistency-especially between very different methods like coupled cluster and AFQMC-supports the conclusion that all three give accurate results for this class of reactions. Consequently, we utilize the least expensive approach, DLPNO-CCSD(T), in studying the remaining reactions (involving the PC and FEC electrolyte solvent components). It should be noted, however, that if the desired precision was chemical accuracy (1 kcal/mol), further improvement of the reference results would be necessary.