Lithium ion batteries have the high operation voltage and superior volumetric/gravimetric energy density with no memory effects among the commercial batteries which are used for energy storage in many electric devices. Batteries are devices which are composed of a negative and a positive electrode where the electrons are transferred through separators (called membranes ) and during discharge process it provides electrical energy for the electronic devices. The electrode material used in Lithium ion battery is mainly carbon based due to its availability, durability and low cost. Recently, there has been growing interest and effort to the synthesis of other metal-based compounds as alternatives to graphite materials, with the aim of improving the capacity and energy density of lithium ion batteries. Therefore, many studies have been focused on tin(Sn), copper(Cu), nickel(Ni), platinum(Pt), cobalt(Co) based intermetallic alloys. The aim of this work is to metallize common lithium ion electrode by galvanic displacement deposition process to increase battery charge capacity. A successful galvanic displacement deposition process of copper (Cu) and Tin (Sn) on Silicon (Si) wafer substrate will be presented in this paper. The plating bath comprises an aqueous solution containing a copper compound, ascorbic acid, ammonium fluoride, and an anti-stress agent. With this process, the use of seed layers to improve adhesion between metal and semiconductor is avoided. And for the deposition of Tin (Sn): the plating bath comprises Sodium Citrate, Sodium Hydroxide, and Tin (II) Sulfate. Throughout the whole experiment formaldehyde (HCHO) has not been used because it is harmful for both animal and environment. Minimization of electrode separation distance maximized the power and energy density in lithium ion battery for this, the second step of this work is to deposit copper and tin onto silicon nanoparticles also by galvanic displacement deposition process with the same plating bath composition used for silicon wafer substrate. The growth and adhesion of thin film is characterized by qualitative scotch tape test, XRD, and XRF techniques. It has been observed that a smooth, homogeneous and better adherent thin film layer obtained on the silicon substrate. To measure the operation perspective of this electrode metal, heat treatment is performed at 200°C on the obtained samples. And then the ion transfer rate of the samples is measured by cyclic voltammetry analysis with scan rate of 50mV/sec and 100mV/sec. All characterization results confirmed that, Copper/Tin/Silicon alloy metal have a great prospective for Lithium ion battery electrode.
Le batterie agli ioni di litio presentano il più alto voltaggio ed un superiore rapporto volume/peso per densità energetica senza effetto memoria rispetto alle batterie normalmente utilizzate. Le batterie sono costituite da un elettrodo che funge da polo positivo ed un secondo elettrodo che funge da polo negativo,gli elettroni durante la scarica si muovono attraverso una membrana dal polo positivo a quello negativo fornendo così energia ai differenti apparecchi collegati. Gli elettrodi sono costituiti da materiale poco costoso e di facile reperimento a base di carbone. Di recente è cresciuto l’ineteresse per la sintesi di composti a base metallica come alternative alla grafite, questo anche allo scopo di migliorare le caratteristiche delle batterie agli ioni di litio. Perciò sono state studiate differenti leghe intermetalliche con stagno (Sn), rame ( Cu), nichel (Ni) , platino (Pt), cobalto (Co). Scopo di questo lavoro è metallizare ( attraverso spostamento galvanico )gli elettrodi normalmente utilizzti nelle batterie al litio per aumentarne la capacità di storage energetico. Come primo approccio il processo di galvanic displacement è stato utilizzato su wafer di silicio ove sono stati depositati rame e stagno in due passaggi distinti. Il bagno di deposizione del rame contiene un sale del rame , acido ascorbico,ammonio fluoruro e un agente detensionante del deposito. Non è stato necessario un pretrattamento del substrato per favorire l’adesione del rame.Per il bagno di deposizione dello stagno I componenti sono: sodiocitrato, sodio idrossido e solfato di stagno (II). Tutti I bagni sono privy di formaldeide (HCHO) in quanto composto pericoloso per la salute di uomini ed animali. Poichè minore è la distanza tra gli elettrodi è maggiore è la densità di energia della batterie agli ioni di litio, in questa seconda fase si è provveduto a depositare sempre per galvanic displacement rame es stagno su nanoparticelle di silicio. L’adesione del deposito metallic è stata valutata qualitativamente con il test dello strappo , mentre crescita e struttura del deposita è stata valutata tramite tecniche XRD e XRF. E’ stata osservata la crescita di un deposito liscio ed omogeneo, aderente sui substrati di sillicio. Per caratterizzare gli elettrodi voltammetrie cicliche prima è dopo la ricottura in forno a 200°C sono state effettuate. Tutti i risultati paiono confermarci che gli elettrodi di Cu/Sn/Silicon possano essere il future per lo sviluppo di migliori batterie agli ioni di litio.
Metallization of Silicon nanoparticles for lithium ion battery electrodes.
AHMED, MONSUR
2015/2016
Abstract
Lithium ion batteries have the high operation voltage and superior volumetric/gravimetric energy density with no memory effects among the commercial batteries which are used for energy storage in many electric devices. Batteries are devices which are composed of a negative and a positive electrode where the electrons are transferred through separators (called membranes ) and during discharge process it provides electrical energy for the electronic devices. The electrode material used in Lithium ion battery is mainly carbon based due to its availability, durability and low cost. Recently, there has been growing interest and effort to the synthesis of other metal-based compounds as alternatives to graphite materials, with the aim of improving the capacity and energy density of lithium ion batteries. Therefore, many studies have been focused on tin(Sn), copper(Cu), nickel(Ni), platinum(Pt), cobalt(Co) based intermetallic alloys. The aim of this work is to metallize common lithium ion electrode by galvanic displacement deposition process to increase battery charge capacity. A successful galvanic displacement deposition process of copper (Cu) and Tin (Sn) on Silicon (Si) wafer substrate will be presented in this paper. The plating bath comprises an aqueous solution containing a copper compound, ascorbic acid, ammonium fluoride, and an anti-stress agent. With this process, the use of seed layers to improve adhesion between metal and semiconductor is avoided. And for the deposition of Tin (Sn): the plating bath comprises Sodium Citrate, Sodium Hydroxide, and Tin (II) Sulfate. Throughout the whole experiment formaldehyde (HCHO) has not been used because it is harmful for both animal and environment. Minimization of electrode separation distance maximized the power and energy density in lithium ion battery for this, the second step of this work is to deposit copper and tin onto silicon nanoparticles also by galvanic displacement deposition process with the same plating bath composition used for silicon wafer substrate. The growth and adhesion of thin film is characterized by qualitative scotch tape test, XRD, and XRF techniques. It has been observed that a smooth, homogeneous and better adherent thin film layer obtained on the silicon substrate. To measure the operation perspective of this electrode metal, heat treatment is performed at 200°C on the obtained samples. And then the ion transfer rate of the samples is measured by cyclic voltammetry analysis with scan rate of 50mV/sec and 100mV/sec. All characterization results confirmed that, Copper/Tin/Silicon alloy metal have a great prospective for Lithium ion battery electrode.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/121243