Tin–Graphite Composite as a High-Capacity Anode for All-Solid-State Li-Ion Batteries

Abstract

The use of composites instead of pure metals as negative electrodes is an alternative strategy for making all-solid-state lithium-ion batteries (Li-SSBs) more viable. This study reports on the properties of a composite electrode (Sn/Graphite) consisting of nanosized Sn (17 wt %) and graphite (83 wt %). The theoretical capacity of this material is 478 mAh g (Sn/Graphite) −1. When mixed with Li 3 PS 4 (LPS) as a solid electrolyte (SE), an areal capacity of 1.75 mAh cm −2 (active mass loading of 3.8 mg cm −2 ) is obtained, which can be increased up to 3.0 mAh cm −2 for 7.6 mg cm −2 . At 0.02 mA cm −2 , the Sn/Graphite electrode delivers a gravimetric capacity of 470 mAh g (Sn/Graphite) −1 , i.e., close to its theoretical value. At 0.1 mA cm −2 , the capacity is 330 mAh g −1 (second cycle) but drops to 84 mAh g −1 after 100 cycles. Solid-state nuclear magnetic resonance spectroscopy (ssNMR) and X-ray photoelectron spectroscopy (XPS) are used to investigate the stability of the solid electrolyte for this cell configuration. Optimization of the electrode is explored by varying the electrode loading between 3.8 and 7.6 mg cm −2 and the SE content between 0 and 65%. For electrodes without any SE, gravimetric capacities (mAh g (Sn/Graphite) −1) and areal capacities (mAh cm −2 ) are lower compared to electrodes with SE; however, their volumetric capacity is higher. This emphasizes the need to optimize the composition of electrodes for SSBs.

Growth of Uniquely Small Tin Clusters on Highly Oriented Pyrolytic Graphite

“…Furthermore, there is evidence that Sn migrates subsurface at elevated temperatures, which would promote the stability of Sn–graphite composites used in alkali-ion batteries and other applications. For applications in Li ion batteries, the small particle sizes for Sn on graphite are desirable for improving stability during cycling by minimizing the absolute volume change during lithiation. ,− …”

“…2,7,8 However, nanosized Sn particles intercalated into graphite sheets have better stability due to the smaller change in absolute volume, and therefore, these Sngraphite composites are promising anode materials that can combine the desired properties of high reversible capacity with good stability upon cycling. 7,8,10 Small Sn particles also maximize the contact between the particle and the carbon support and result in superior electrochemical performance. 7 In general, the growth of metals on HOPG is consistent with high mobility of atoms on the surface and the formation of thermodynamically favored three-dimensional (3D) clusters.…”

“…2,7−10 Metallic Sn anodes have a high Li ion storage capacity, but are mechanically unstable due to the large volume expansion during lithiation. 2,7,8 However, nanosized Sn particles intercalated into graphite sheets have better stability due to the smaller change in absolute volume, and therefore, these Sngraphite composites are promising anode materials that can combine the desired properties of high reversible capacity with good stability upon cycling. 7,8,10 Small Sn particles also maximize the contact between the particle and the carbon support and result in superior electrochemical performance.…”

“…Understanding the growth of Sn-based clusters on surfaces is important for a variety of applications in battery electrodes and microelectronics, , and in catalysis and electrocatalysis, in which bimetallic Sn–Pt clusters have superior selectivity for the desired products compared to Pt. − For example, knowledge of the interface between Sn and carbon supports is valuable for applications involving the Sn-carbon nanocomposites used in the anodes of Li ion batteries. ,− Metallic Sn anodes have a high Li ion storage capacity, but are mechanically unstable due to the large volume expansion during lithiation. ,, However, nanosized Sn particles intercalated into graphite sheets have better stability due to the smaller change in absolute volume, and therefore, these Sn-graphite composites are promising anode materials that can combine the desired properties of high reversible capacity with good stability upon cycling. ,, Small Sn particles also maximize the contact between the particle and the carbon support and result in superior electrochemical performance …”

Copper Thiophosphate (Cu3PS4) as an Electrode Material for Lithium Solid‐State Batteries with Lithium Thiophosphate (β–Li3PS4) Electrolyte

“…Conversion reactions can be classified into reactions with direct phase transformations or those that undergo decomposition reactions. Examples of the former include Li-S, [6] or Li alloys such as Li-Si, [7] Li-In, [8] or Li-Sn, [9] while the latter typically occur when Li (or Na) reacts with compounds such as M a X b (where M = Fe, Co, Ni, Cu, etc., and X = S, O, P, F, etc.). For example, various phosphides and sulfides such as NiP 2 , [10] Sn 4 P 3 , [11] FeS 2 , [12] Co 9 S 8 , [13] MoS 2 , [14] and CuS [15] have been studied as electrode materials for SSBs that are known to undergo decomposition reactions.…”