Novel low cost / electrically conductive / Li-ion corrosion resistant nitrogen atoms doped ultrananocrystalline diamond (N-UNCD) coating provides excellent chemically robust encapsulation of commercial natural graphite (NG)/copper (Cu) anodes and new textured Si-based anodes, currently under development for Li-ion batteries (LIB), providing a solution to the problem of LIBs’ anode materials degradation due to chemical corrosion induced by Li ions.
The N-UNCD encapsulating coating allows for good conductivity of both electrons and Li-ions while exhibiting outstanding chemical and electro-chemical inertness to Li ions-induced corrosion (see Fig. 1 enclosed), eliminating de Li-induced chemical corrosion of graphite powder in current commercial graphite/copper composite anodes (see Fig. 1), which result in degradation of the capacity energy after undesirable relatively short numbers of charge/discharge cycles of LIBs (see Fig. 1). In addition, the electrically conductive N-UNCD coating produces a substantial increase in the mechanical strength of the anode’s graphite powder and also produces the same results for structured Si anodes, under investigation, resulting in the formation of robust SEI films, which effectively eliminate unceasingly cracking of SEI, observed in graphite/copper anodes, which expose fresh graphite anode surface, thus, repairing of the SEI by electro-chemical reduction of the electrolyte and the formation of additional SEI compounds, which increase the impedance for the lithium ion diffusion and causes the electrolyte to be prematurely depleted in anodes without the N-UNCD coating. In addition to the excellent protection to chemical attack of anodes, new preliminary R&D indicates that electrically conductive N-UNCD coatings can also be used to coat LIB’s oxide cathodes to protect them from Li-induced corrosion, as well. Also, insulating corrosion resistant UNCD coating can be used to coat the inner walls of novel metallic aluminum LIB’s cases and membranes to protect them from corrosion induced by the Li-based battery environment, and thus enabling to use aluminum as a LIB’s case, without any corrosion.
Key applications of the new LIBs with the novel electrically conductive N-UNCD and insulating UNCD coatings, under development for initial insertion in the market are (see Fig. 2): 1) cell phones that will be rechargeable every 3-4 days as opposed to every night with current LIBs, and order of magnitude safer, with N-UNCD coating protecting electrodes from overheating; 2) Defibrillator/ Pacemakers with ≥10x longer life/safer than those powered by current LIBs; 3) portable computers with ≥ 10x longer life before charging the LIB; 4) in the future, application to electric cars’ batteries may produce cars with ≥10x longer driving range before charging, as needed for current cars’ batteries.