Lithium Sulfur Battery Pulse Charging Insulating Layer

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Solution Overview

Problem

Lithium sulfur batteries face performance degradation due to the formation of an insulating lithium sulfide layer on the cathode, leading to high ohmic resistance and voltage losses during charging, which reduces coulombic efficiency and active species availability.

Innovation Solution

Applying controlled voltage pulses during the initial charging phase to create surface defects on lithium sulfide particles, facilitating their dissolution and reactivity, thereby removing the insulating layer and restoring active species availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If constant current charging is applied directly after discharge, then charging speed is maintained, but the insulating lithium sulfide layer causes high ohmic resistance and voltage losses

Engineering Contradiction:

Improvecharging speedVSAvoidvoltage losses

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent applies a preliminary voltage pulse treatment before constant current charging to modify the lithium sulfide layer. These pulses create surface defects and increase reactivity of the insulating layer, preparing it for subsequent charging. This preliminary action prevents the high ohmic resistance and voltage losses that would otherwise occur during constant current charging.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs periodic voltage pulses with specific frequencies and durations during the charging process. These periodic pulses disrupt the insulating lithium sulfide layer, preventing continuous high resistance conditions. The pulsed nature allows the system to maintain charging speed while periodically reducing ohmic resistance and voltage losses.

Inventive Principle:

Principle #19Periodic action

2Reliability

If voltage pulses are applied to remove the insulating layer, then coulombic efficiency improves, but charge cycle duration increases

Engineering Contradiction:

Improvecoulombic efficiencyVSAvoidcharge cycle duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies voltage pulses at specific voltage levels and durations that are optimized to achieve sufficient removal of the insulating layer without over-treating the battery. The pulse parameters (voltage, duration, frequency) are carefully controlled to provide just enough action to improve coulombic efficiency while minimizing the time penalty. This partial action approach balances efficiency improvement with acceptable charging time.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent dynamically adjusts voltage pulse parameters during charging based on battery state. By changing voltage amplitude, pulse width, and frequency according to the charging progress and battery condition, the system optimizes the balance between removing the insulating layer (improving coulombic efficiency) and maintaining acceptable charge cycle duration. Parameter adaptation allows efficient charging without excessive time loss.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves coulombic efficiency, enhances charge efficiency, decreases charge cycle duration, and reclaims active sulfur particles by disrupting the insulating layer on the cathode, thereby maintaining battery performance.

Implementation Method 1

Applying controlled voltage pulses during the initial charging phase to create surface defects on lithium sulfide particles, facilitating their dissolution and reactivity

Methodology Applied

Scientific EffectSurface defect creation:

Implementation Method 2

facilitating their dissolution and reactivity, thereby removing the insulating layer and restoring active species availability

Methodology Applied

Scientific EffectElectrochemical dissolution: Electrolysis

Data Source

PatentUS9866056B2Lithium sulfur battery pulse charging method and pulse waveform

Publication Date: 2018.01.09 NISSAN MOTOR CO LTD

AI summary

Provided are methods and apparatus for charging a lithium sulfur (Li—S) battery. The Li—S battery has at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method provides controlled application of voltage pulses at the beginning of the charging process. An application period is initiated after a discharge cycle of the Li—S battery is complete. During the application period, voltage pulses are provided to the Li—S battery. The voltage pulses are less than a constant current charging voltage. Constant current charging is initiated after the application period has elapsed.