Interfacial Chemistry Control for Performance Enhancement of Micron Tin-Nickel/Graphite Battery Anode

Abstract

Designing and controlling the anode-electrolyte interfacial chemistry of a micron Sn-Ni/graphite composite battery anode led to the formation of a stable solid electrolyte interphase (SEI) layer. We utilized fluoroethylene carbonate (FEC)-based electrolyte that is more interfacially compatible than an EC-based electrolyte, trimethyl phosphite electrolyte additive that reduces the attack of LiPF 6 -derived acidic species in the electrolyte, and the addition of a low fraction of SnF 2 to anode for capturing the F anions of HF present in the electrolyte. Mechanistic surface chemistry studies using ATR FTIR and X-ray photoelectron spectroscopy revealed that the SnF 2 transforms to SnF 4 by capturing F anions, while FEC and phosphite provide a surface protective and robust SEI. The interfacially controlled composite anode with a tuned content of graphite exhibits good cycling stability (90% retention at the 50 th cycle) with high discharge capacity of ∼800 mAhg −1 of tin, in contrast to a rapid capacity fade in the conventional electrolyte.

Unveiling the Roles of Formation Process in Improving Cycling Performance of Magnesium Stannide Composite Anode for Magnesium‐Ion Batteries

“…The pattern obtained after 60 cycles ( C 60), which was ended as charged, is the same to those of charged anodes ( C 1, C 2, C 3). Slightly weakened peak intensity of recovered Mg 2 Sn phase upon charge, compared to pristine, might originate from a decrease in crystallinity or structural ordering by the possible occurrence of particle cracking event of this microsized Mg 2 Sn particles due to volume change, as often observed in the Sn‐based anodes in Li‐ion batteries . The peak of graphite is present at all states, confirming the role of graphite of being an electrochemically inactive but conductive agent.…”

“…Curve fitting was conducted on the broad Sn 3d 5/2 peaks ( Figure a) at 490–480 eV and Mg 2p peaks at 54–47 eV to determine the relative concentrations of various surface Sn and Mg species, whose fitting results are summarized in Figure a′ and Figure b′, respectively. First, the Sn 3d 5/2 spectrum of pristine anode (Figure a) exhibits that its surface consists of 38.2% Mg 2 Sn, as confirmed by the Mg 2p spectrum (Figure b), 16% Sn, 10.7% SnO, and 35.1% SnO 2 , as supported by O 1s spectrum ( Figure a) . The presence of surface Sn metal at pristine anode is likely associated with the trace of unreacted Sn during Mg 2 Sn synthesis, probably as remained at the surface, since it was not detectable in the powder XRD pattern (Figure ) that is a bulk analysis tool with the detection depth of ≈5 µm from the surface.…”

Binder-free SnO2–TiO2 composite anode with high durability for lithium-ion batteries

“…42,44 Interestingly, tin uoride components such as SnF 4 (488.1 eV of Sn 3d 7/2 ) and SnF 2 (487.4 eV of Sn 3d 7/2 ) also exist on the surface. 45,46 From the F 1s spectrum, it is seen that the tin uoride composites clearly appear aer the potential shock ( Fig. S4 †); these are attributed to residual F À ions, which were trapped inside the MCs.…”

Mechanisms for Stable Solid Electrolyte Interphase Formation and Improved Cycling Stability of Tin‐Based Battery Anode in Fluoroethylene Carbonate‐Containing Electrolyte

“…Surface degradation can also occur by the dissolution of surface oxide by HF. The most explored approaches to improve the interfacial (SEI) stability have been the use of electrolyte additives, such as phosphite and fluoroethylene carbonate (FEC) but just few studies have focused on investigating the SEI formation on Sn‐based anode . Despite some improvement, challenges in the improvement of performance and SEI stability still remain.…”