TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The first Prussian blue analog material includes copper hexacyanoferrate, copper hexacyanomanganate, manganese hexacyanomanganate, or manganese hexacyanomanganate. The aqueous electrolyte includes at least one additive comprising an amine and/or its oxide, where the amine or its oxide includes pyridine-N-oxide. The aqueous electrolyte includes many anions X1 so that a reaction of the anion X1 with the first cation P1 is configured to form an insoluble compound containing first cation P1 and anion X1, where anion X1 includes at least one anion comprising fluoride, carbonate, oxalate, and/or phosphate. The first cation P1 includes at least one cation comprising a copper cation, manganese cation, zinc cation, and/or iron cation. The size of the nanoparticle is 50 nm. In the electrochemical apparatus (E2): the nanoparticles include agglomerations of the nanoparticles, where each agglomeration has a size of 1-5 microns; each nanoparticle has a size of 200-1000 nm, or size less than 1 micron; and the first electrode operates within a first potential window when disposed in the aqueous electrolyte, where the first conformal polymer layer forms a dissolution product in the aqueous electrolyte with the dissolution product chemically inactive within the first potential window. The polymer-coating-forming constituents include at least one additive comprising an amine and/or its oxide. Preferred Method: The first specific chemical formula includes manganese hexacyanomanganate, where the depositing step includes polymerizing polypyrrole on the first electrode.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The first electrode includes a first potential window when disposed in the aqueous electrolyte, where the first conformal polymer layer forms a dissolution product in the aqueous electrolyte with the dissolution product chemically inactive within the first potential window. The electrochemical apparatus (E1) and (E2) further comprises: a second electrode disposed in the aqueous electrolyte, where the second electrode includes a second Prussian blue analog material conforming to (I) and the second Prussian blue analog material has a second specific formula which is different from the first specific formula, and the second Prussian blue analog material has a third rate of electrochemical capacity loss when disposed in the aqueous electrolyte; and a second conformal polymer layer disposed on the second electrode, where the second conformal polymer layer is conductive to the ions, and the first electrode, second electrode, and aqueous electrolyte are configured as a rechargeable energy storage cell.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The aqueous electrolyte includes at least one additive comprising a simple thiol and/or a complex thiol. The simple thiol includes decanethiol. The complex thiol includes cysteine.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The first conformal polymer layer includes a polypyrrole compound, or polythiophene compound. Preferred Method: The step (a1) includes: depositing the first conformal polymer layer by an oxidative polymerization sequence; or dissolving many polymer-coating-forming constituents into the aqueous electrolyte, and coating the first electrode with the first conformal polymer layer formed from the polymer-coating-forming constituents in the aqueous electrolyte during step (b1) and responsive to an operation of the electrochemical apparatus. The first specific formula includes copper hexacyanoferrate, where the depositing step includes polymerizing polypyrrole on the first electrode. The depositing step includes depositing the first conformal polymer layer using an oxidative electroplating method, or an reductive electroplating method. The first electrode includes: many nanoparticles of the first Prussian blue analog material with each nanoparticle including an outside surface, where the step (a1) includes disposing the first conformal polymer layer on the outside surfaces; and many agglomerations, where each agglomeration includes many nanoparticles of the first Prussian blue analog material with each nanoparticle including an outside surface, where the step (a1) includes disposing the first conformal polymer layer on the outside surfaces. Preferred Definitions:    A1 = Na+, K+, Li+, NH4+, Mg2+, and/or Ca2+;    P1 = V2+, V3+, Cr2+, Cr3+, Mn2+, Mn3+, Fe2+, Fe3+, Co2+, Co3+, Ni2+, Cu+, Cu2+, Zn2+, Al3+, Sn2+, In3+, and/or Pb2+;    R = V2+, V3+, CO2+, CO3+, Ru2+, Ru3+, Os2+, Os3+, Ir2+, Ir3+, Pt2+, Cr2+, Cr3+, Mn2+, Mn3+, Fe2+, Fe3+ and/or Pt3+; and    L1 = CO, NO and/or Cl-.