Control of Graphene Heteroatoms in a Microball Si@Graphene Composite Anode for High-Energy-Density Lithium-Ion Full Cells

Abstract

The use of Si and nitrogen-doped graphene to fabricate composite anodes in lithium-ion batteries (LIBs) is attracting intense attention. However, the reported strategies are limited to achieving a cost-effective, scalable, and facile approach. In particular, many reports on Si/N-graphene (N-Gra) anodes cannot achieve a high first discharge capacity while retaining a high Coulombic efficiency (CE). Herein, we report a Si@N-Gra composite with core−shelled microballs of Si NPs and electrochemically exfoliated graphene by NH 3 as a nitrogen source. We use H 2 and NH 3 to control the O and N content and to optimize the anode performance.

Silicon‐Based Lithium Ion Battery Systems: State‐of‐the‐Art from Half and Full Cell Viewpoint

“…Su and coworkers verified the feasibility of the pre‐lithiation technology. [ 120 ] Specifically, before assembling an NCM811||Si@N‐ECGB full cell, the Si@N‐ECGB anode was pre‐lithiated by electrochemical deposition technology in a half cell. Benefitting from the increase in Li‐inventory (20% of capacity), the NCM811||Si@N‐ECGB full cell had a high reversible capacity of 170 mAh g −1 and a capacity retention of 84% after 100 cycles.…”

“…However, the assembled LCO||Si/CNT full cell achieved a much lower capacity retention of 76% after only 50 cycles. Evaluating the compatibility of Si-based anode materials, cathode materials, electrolytes, binders, and separators in advanced Si-based full cell systems is necessary to balance their energy densities, lifetime, operating security, and cost, [120,163,164] thereby providing a possibility for further practical applications. Pre-lithiation technology has attracted widespread attention due to the ability to compensate for the irreversible Li + consumption in Si-based full cell systems, which could further improve their ICE values, energy densities, and lifetime.…”

“…In addition to superior half cell performance, their full cells with conventional LFP and LCO cathodes, high capacity NCM and LiNi x Co y Al z O 2 (NCA, x + y + z = 1) cathodes, as well as high voltage LiNi 0.5 Mn 1.5 O 4 (LMNO) cathodes have also been developed to balance their cost, energy densities, and lifetime. [ 119–122 ] II) From the perspective of half cells, SiO x materials have attracted much attention due to their relatively low volume changes (≈100%). [ 123–127 ] However, due to the formation of by‐products (SEI and Li 4 SiO 4 ) in the initial lithiation process, SiO x materials usually have poor ICE values and thus need to be improved.…”

Recent progress on performance modulation and mechanism study of silicon-based anodes

“…Su et al developed a pre-lithiation technique. 118 Firstly, pre-lithiated Si@N-ECGB anodes were prepared though electrodeposition technology before equipping a full battery with NCM811. Owing to the improvement in Li-storage (20%), the reversible capacity of the full battery by matching NCM811 and Si@N-ECGB could reach 170 mA h g −1 .…”

Ultrathin Si Nanosheets Dispersed in Graphene Matrix Enable Stable Interface and High Rate Capability of Anode for Lithium‐ion Batteries

“…Various strategies have been attempted to tackle the above bottlenecks in the past decade, mainly including the design of Si/C composites [ 7–14 ] and the synthesis of nanosized Si. [ 15–25 ] Although these strategies can substantially improve the Li + /e − transport and cycling stability of Si, they have not yet been practically deployed to achieve the required rate capability and long‐term cyclability of LIBs.…”